Orthodontics

Skeletal Maturity Indicators Important Notes

• Skeletal maturity indicators
  • Hand wrist radiographs
  • Skeletal maturation using cervical vertebrae
  • Clinical and radiographic examination of stages of tooth development
• Fishman’s skeletal maturity indicator
  • It evaluates hand-wrist radiographs making use of anatomical sites located on the thumb, third finger, fifth finger, and radius
  • 11 skeletal maturity indicators were described covering the entire period of adolescent development
  • Interpretation uses four stages of bone maturation
    • Epiphysis equal in width to diaphysis
    • Appearance of abductor sesamoid of the thumb
    • Capping of epiphysis
    • Fusion of epiphysis

Skeletal Maturity Indicators Short Essays

Question 1. Hand Wrist Radiograph.
Answer.

It is one of the skeletal maturity indicators

Significance Of Hand Wrist Radiograph:

• Describes ossification and union of small bones of hand and wrist
• Determines skeletal age of patients

Indications Of Hand Wrist Radiograph:

• In the discrepancy between dental and chronological age
• Determines the skeletal age of the patient
• Determines skeletal malocclusion
• Predict future skeletal growth
• Predict pubertal growth spurt
• Aid in research
• Assess the growth status of individual

Methods Of Hand Wrist Radiograph:

• Atlas method by Greulich and Pyle
• Bjork, Grave, and Brown’s method
• Fishman’s skeletal maturity indicator
• Hagg and Taranger’s method

Anatomy Of Hand Wrist:

Consist of:

• Distal ends of long bones of the forearm
• Carpals
• Metacarpals
• Phalanges

Question 2. Maturity Indicators.
Answer.

Importance Of Maturity Indicators:

• Determine the stage of maturity
• Assess skeletal growth
• Decides the treatment planning
• Helps in objective diagnosis
• Assess different ossification centers

Methods Of Maturity Indicators:

• Hand wrist Radiograph
• Cervical vertebrae
  • By Hassel and Farman
  • Shapes of cervical vertebrae determine stages of development
  • Shapes of C3 and C4 are compared

Read And Learn More: Orthodontics Short And Long Essay Question And Answers 

• • Inferior vertebral borders were examined
    • Flat – when immature
    • Concave – when matured
  • Six stages in vertebral development are viewed
• Tooth Mineralization
  • Selected teeth – lower canine
  • Calcification patterns and stages of mineralization are examined
• Maxillary sinus
• Frontal sinus

Question 3. Fishman’s Skeletal Maturity Indicators.
Answer.

Skeletal Maturity Indicators Short Questions And Answers

Question 1. MP 3.
Answer.

• Used in maturation assessment by Hagg and Taranger
• Describes changes in third finger middle phalanx

Question 2. Stages of Maturation using Cervical Vertebrae.
Answer.

Question 3. Carpal index.
Answer.

• One of the skeletal maturity indicator
• Used as a part of hand wrist
• Carpals – consist of eight small bones arranged in
  • Proximal Row
    • Scaphoid
    • Lunate
    • Triquetral
    • Pisiform
  • Distal row
    • Trapezium
    • Trapezoid
    • Capitate
    • Hamate
      • These bones show specific patterns of appearance, ossification, and union
      • These are compared with standards

Skeletal Maturity Indicators Viva Voce

• Skeletal age is useful throughout the post-natal growth period
• Dental age as a maturity indicator is useful from birth to early adolescence
• Morphological age as a maturity indicator is useful from late infancy to early adulthood
• 29 bones are included in the hand-wrist region
• The radius and ulna are long bones of the hawristist region there are 8 carpal bones in the hand wrist
• There are 5 metacarpal bones in the hand wrist
• Each digit of the hand has proximal middle and distal phalanges
• Sesamoid is small nodular bone
• There are 1 primary ossification center and one secondary ossification center for each metacarpal bone

Habits Definition

• Habit
  • It is defined as the tendency towards an act that has become a repeated performance relatively fixed, consistent, and easy to perform by an individual.
• Tongue thrusting
  • It is the habit of thrusting the tongue forward against the teeth or in between while swallowing

Habits Important Notes

• Types of mouth breathing

• Types of tongue thrusting
  • Type 1 – Non deforming
  • Type 2 – Deforming anterior tongue thrust
    • Subgroup 1 – Anterior open bite
    • Sub group 2 – Anterior proclination
    • Sub-group 3 – Posterior cross bite
  • Type 3 – Deforming lateral tongue thrust
    • Subgroup 1 – Posterior open bite
    • Sub group 2 – Posterior cross bite
    • Subgroup 3 – Deep over bite
  • Type 4 – Deforming anterior and lateral tongue thrust
    • Sub-group 1 – Anterior and Posterior open bite
    • Subgroup 2 – Proclination of anterior
    • Sub-group 3 – Posterior cross bite
  • Simple Classification:
    • Simple tongue thrust
    • Complex tongue thrust
• Long face syndrome – features
  • Short and flaccid upper lip
  • Constricted upper arch
  • Frequent occurrence of tonsillitis
  • Allergic rhinitis
  • Otitis media
  • Anterior marginal gingivitis
• Features of thumb sucking
  • Proclination of maxillary anteriors
  • SNA angle is increased
  • Anterior open bite
  • Narrow and long maxillary arch
  • Hypotonic upper lip

Habits Long Essays

Question 1. Define and classify malocclusion. Describe in detail role of lip biting habit in development of malocclusion.
Answer.

Malocclusion: Any deviation from normal occlusion is called malocclusion

Classification Of Malocclusion:

Intra-arch Malocclusion: Includes variations in individual tooth position and affecting that of group of teeth within an arch

• Distal tipping: Crown of tooth is tilted distally
• Mesial tipping: Crown of tooth is tilted mesially
• Buccal tipping: Crown of tooth is tilted labially
• Palatal tipping: Crown of tooth is tilted palatally
• Mesial displacement: Bodily movement of tooth is mesial direction
• Distal displacement: Bodily movement of tooth is distal direction
• Buccal displacement: Bodily movement of tooth bucally
• Lingual displacement: Bodily movement of tooth lingually
• Infra occlusion: Tooth has not erupted enough as compared to other teeth in the arch
• Supra occlusion: Tooth has over erupted as compated to other teeth in the arch
• Rotations: Tooth movement around its long axis
• Disto-lingual/Mesio-buccal rotation: Movement of tooth around its long axis such that distal aspect is more lingually placed
• Mesio-lingual/Disto-buccal rottion: Movement of tooth around its long axis such that mesial aspect is more lingually placed
• Transposition: Two teeth have exchanged their places.

Read And Learn More: Orthodontics Short And Long Essay Question And Answers 

Inter-Arch Malocclusion

• Includes abnormal relationship between two teeth or groups of teeth of one arch to other arch.

Sagittal Plane Malocclusion:

• Pre-normal occlusion – Mandible is forwardly placed when the patient bites in centric occlusion
• Post-normal occlusion – Mandible is distally placed when the patient bites in centric occlusion

Vertical Plane Malocclusion:

• Deep bite
• Open bite

Transverse Plane Malocclusion:

• Cross bite

Skeletal Malocclusion:

• Occur due to abnormalites in maxilla/mandible
  • Sagittal Plane
    • Prognathism – forwardly placement of jaw
    • Retrognathism – backwardly placement of jaw
  • Transverse Plane
    • Narrowing of jaw
    • Widening of jaw
• Vertical Plane – Effecting lower facial height

Lip Biting Habit

• Lip biting often involves the lover lip that is turned inwards
• Due to it pressure is exerted on the lingual surfaces of maxillary anteriors

Features

• Proclined upper anteriors and retroclined lower anteriors
• Hypertrophic and redundant lower lip
• Cracking of lip

Skeletal Malocclusion Management

• Use of lip bumpers
  • To keep lips away
  • To improve axial inclination of the anterior teeth

Question 2. Define malocclusion. Classify etiology of it. Dicuss clinical picture and management of thumb sucking habit.
Answer.

Malocclusion: Any deviation from normal occlusion is called malocclusion

Etiology Of Malocclusion:

Classification Of Malocclusion: Graber’s classification

General Factors:

• Hereditary
• Congenital
• Environment – Prenatal, Postnatal
• Metabolic
• Nutritional
• Habits
• Posture
• Trauma and accidents

Local Factors:

• Anomalies of number
• Anomalies of tooth size
• Anomalies of tooth shape
• Abnormal labial frenum
• Abnormal eruptive path
• Premature loss of deciduous
• Prolonged retention of deciduous
• Delayed eruption of permanent teeth
• Ankylosis
• Dental caries
• Improper dental restoration

Thumb Sucking Habit:

Clinical Features:

• Labial tipping of maxillary anteriors
• Proclination of maxillary anteriors
• Increased overjet
• Lingual tipping of mandibular anteriors
• Anterior open bite
• Supra eruption of posteriors
• Narrowing of maxillary arch
• Hypotonic upper lip
• Hyperactive mentalis activity

Etiology Of Malocclusion Management:

• Psychological approach
  • Dunlops Beta hypothesis
  • Dunlop suggests that the child should be asked to sit in front of mirror and to suck his thumb
  • This becomes effective when the child is asked to do it when he is engaged in an enjoyable activity
• Mechanical aids
  • Habit breaking appliances
    • Passive removable appliances are
    • Palatal crib and clasps on posteriors creates interference during habit
  • Fixed appliances
    • Bands on molars fabricated by heavy guage stainless steel wire

• • Other aids
    • Bandaging the thumb
    • Bandaging of elbow
• Chemical aids:
  • Pepper
  • Quinine
  • Asafoetida

Question 3. Define habits, classify and discuss tongue thrust habits, its clinical features and its treatment.
Answer.

Habit: It is defined as the tendency towards an act that has become a repeared performance relatively fixed, consistent and easy to perform by an individual.

Tongue Thrust Habit:

Classification Of Tongue Thrust Habit:

• Type 1: Non deforming
• Type 2: Deforming anterior tongue thrust
  • Sub group 1 – Anterior open bite
  • Sub group 2 – Anterior proclination
  • Sub group 3 – Posterior cross bite
• Type 3 – Deforming lateral tongue thrust
  • Sub group 1 – Posterior open bite
  • Sub group 2 – Posterior cross bite
  • Sub group 3 – Deep over bite
• Type 4 – Deforming anterior and lateral tongue thrust
  • Sub group 1 – Anterior and Posterior open bite
  • Sub group 2 – Proclination of anterior
  • Sub group 3 – Posterior cross bite

Simple Classification:

• Simple tongue thrust
• Complex tongue thrust

Clinical Features Of Tongue Thrust Habit:

• Simple Tongue thrust:
  • Normal tooth contact during swallowing
  • Anterior lip seal
  • Good intercuspation
  • Anterior open bite
  • Abnormal mentalis activity
• Complex Tongue Thrust:
  • During swallowing, teeth are apart
  • Absence of temporal muscle constriction
  • Poor occlusion
  • Contraction of circumoral muscles during swallowing

Other Features

• Anterior proclination
• Anterior open bite
• Bimaxillary protrusion
• Posterior open bite
• Posterior cross bite

Tongue Thrust Habit Management

Habit Interception:

• Habit breaking appliances removable cribs/rakes are fabricated which creates interference during habit.
• Teach the correct method of swallowing
• Muscle exercises

Treatment of malocclusion: By removable/fixed orthodontic appliances.

Habits Short Essays

Question 1. Habits.
Answer.

Definition: It is defined as the tendency towards an act that has become a repeated performance relatively fixed, consistent and easy to perform by an individual.

Classification Of Habits:

• According to William James
  • Useful habits – include habits essential for normal function
  • Harmful habits – habits that have deleterious effects
• Empty and Meaningful Habits:
  • Empty habits – not associated with psychological problems
  • Meaningful – associated with psychological bearing
• Pressure, non-pressure and bitting habits:
  • Pressure habits – thumb sucking, lip sucking, tongue thrusting
  • Non-pressure habtis – mouth breathing
  • Biting habits – nail biting
• Compulsive:
  • Deep rooted habits

Non-Compulsive – Learned Habits

Etiology:

• Anatomical – Ex. Posture of tongue
• Pathological – Ex. Tonsilitis
• Emotional – Ex. Digit sucking
• Imitation
• Random behaviour
• Equilibrium theory

Question 2. Habit Breaking Appliances.
Answer.

• Thumb sucking:
  • Removable:
    • Tongue spikes
    • Tongue guards
    • Blue glass appliance
    • Spurs rakes
• Fixed:
  • Quad helix
  • Hay rakes
  • Palatal crib
• Bruxism: Night guards
• Mouth breathing: Oral screen

Question 3. Mouth Breathing.
Answer.

Classification Of Mouth Breathing:

• Based on etiology
  • Obstructive – Due to nasal obstruction
  • Habitual – Even after removal of obstruction
  • Anatomic – Due to lip morphology

Clinical Features:

• Extra-oral
  • Long, narrow face, blank face
  • Narrow nose
  • Short upper lip
• Intra-oral:
  • Constricted maxillary arch
  • Increased overjet, anterior Open bite
  • Anterior marginal gingivitis
  • Dryness of mouth

Diagnosis Of Mouth Breathing:

• Clinical examination – Fogging of mouth mirrors
• Cephalometrics – shows long face
• Rhinomanometry – to assess nasal passage

Mouth Breathing Management:

• Removal of nasal obstruction – By surgery
• Interception of habit – By vestibular screen
  • RME – Decreases nasal air resistance

Question 4. Sucking and Suckling.
Answer.

Suckling:

• It is a natural process of breast feeding
• Here, nipple is drawn into mouth. Tongue lies between lower gum pad and nipple
• Creates negative pressure
• Milk passes between faucial pillars and lateral channels of pharynx
• Cheek muscles plays an important role in it
• They contract while suckling, thus good development of muscle occurs

Sucking:

• It is bottle feeding
• Through it milk is sucked easily with less effort
• Thus cheek muscles does not have to work more
• This results in under development of cheek muscles
• May lead to malocclusion

Habits Short Questions And Answers

Question 1. Simple and complex tongue thrust
Answer.

• Simple Tongue thrust
  • Normal tooth contact during swallowing
  • Anterior lip seal
  • Good intercuspation
  • Anterior open bite
  • Abnormal mentalis activity
• Complex Tongue Thrust:
  • During swallowing, teeth are apart
  • Absence of temporal muscle constriction
  • Poor occlusion
  • Contraction of circumoral muscles during swallowing

Question 2. Etiology of tongue thrust.
Answer.

• Genetic factors – Hypertonic orbicularis oris
• Learned behaviour – Habitual
• Maturational – Retained infantile swallowing
• Mechanical restriction – Macroglossia
• Neurological disturbance – Hyposensitive palate
• Psychogenic factors – Discontinuation of other habits

Question 3. Habits.
Answer.

It is defined as the tendency towards an act that has become a repeated performance relatively fixed, consistent an easy to perform by an individual.

Etiology Of Habits:

• Anatomical – Ex. Posture of tongue
• Pathological – Ex. Tonsilitis
• Emotional – Ex. Digit sucking
• Imitation
• Random behaviour
• Equilibrium theory

Question 4. Mouth breathing habit.
Answer.

Clinical Features:

• Extra-oral:
  • Long, narrow face, blank face
  • Narrow nose
  • Short upper lip
• Intra-oral:
  • Constricted maxillary arch
  • Increased overjet, anterior Open bite
  • Anterior marginal gingivitis
  • Dryness of mouth

Mouth Breathing Habit Management:

• Removal of nasal obstruction – By surgery
• Interception of habit – By vestibular screen
• RME – Decreases nasal air resistance

Habits Viva Voce

• Psychologic management should be done prior to using mechanical aids while treating thumb sucking
• Psychological stress is most common cause of bruxism
• Presence of clean nails and callus on finger is commonly associated with thumb sucking
• Femite liquid applied on the thumb and nail of child discourage sucking
• Long face syndrome is associated with mouth breathers

Etiology Of Malocclusion Important Notes

Causes of malocclusion:

• General Factors:
  • Hereditary
  • Congenital
  • Environment – Prenatal, Postnatal
  • Metabolic
  • Nutritional
  • Habits
  • Posture
  • Trauma and accidents
• Local Factors:
  • Anomalies of number
  • Anomalies of tooth size
  • Anomalies of tooth shape
  • Abnormal labial frenum
  • Abnormal eruptive path
  • Premature loss of deciduous
  • Prolonged retention of deciduous
  • Delayed eruption of permanent teeth
  • Ankylosis
  • Dental caries
  • Improper dental restoration

• Acromegaly features
  • Accelerated development of mandible
  • Hypercementosis
  • Macroglossia
  • Early eruption of dentition

Etiology Of Malocclusion Long Essays

Question 1. Classify various factors in etiology of malocclusion. Elaborate on endocrinal factors.
Answer.

Classification Of Etiology of Malocclusion: Graber’s classification

General Factors:

• Hereditary
• Congenital
• Environment – Prenatal, Postnatal
• Metabolic
• Nutritional
• Habits
• Posture
• Trauma and accidents

Read And Learn More: Orthodontics Short And Long Essay Question And Answers 

Local Factors:

• Anomalies of number
• Anomalies of tooth size
• Anomalies of tooth shape
• Abnormal labial frenum
• Premature loss of deciduous
• Prolonged retention of deciduous
• Delayed eruption of permanent teeth
• Ankylosis
• Dental caries
• Improper dental restoration

Endocrinal Imbalance Causing Malocclusion:

Disorders and their features:

Question 2. Discuss local of malocclusion./Discuss the environmental or local causes of malocclusion in detail.
Answer.

Local Causes:

Anomalies in number of teeth:

• Normal no. of teeth should be present
• Extra/missing teeth creates malocclusion

• Anomalies of Tooth size: For normal occlusion harmony between tooth size and arch length must be present

• Anomalies of Tooth shape:

• Abnormal labial frenum: High frenal attachment of maxillary labial frenum causes midline diastema
• Premature loss of deciduous:
  • Effects: Migration of adjacent teeth
    • Prevent eruption of permanent successor
    • May lead to impaction
• Prolonged retention of deciduous teeth:
  • Effects: Prevent eruption of permanent
    • Abnormal eruptive path
• Delayed Eruption of Permanent:
  • Causes:
    • Congenital
    • Supernumerary teeth
    • Mucosal barrier
    • Premature loss of deciduous
    • Endocrinal disorder
    • Root fragments of deciduous
• Abnormal Eruptive path:
  • Causes:
    • Supernumerary teeth
    • Impacted teeth
    • Retained deciduous
    • Bony barrier
• Ankylosis:
  • Root surface is directly fused to bone
  • Absence of PDL
  • Causes:
    • Trauma
    • Infections
    • Congenital
    • Endocrinal disorders
  • Effects:
    • Causes submerge of teeth
    • Migration of adjacent teeth
• Dental Caries:
  • Effects:
    • Premature loss of deciduous
    • Migration of adjacent
    • Decrease in arch length

• • • Abnormal axial inclination
    • Supra-eruption of opposing teeth
• Improper Dental Restoration:
  • Over contoured
    • Effects:
      • Functional shift of mandible
  • Under-contoured
    • Effects:
      • Supra-eruption of opposing teeth
      • Loss of arch length
      • Food lodgement
      • Periodontal weakening of teeth

Etiology Of Malocclusion Short Questions And Answers

Question 1. Ankylosis.
Answer.

• Root surface is directly fused to bone
• Absence of PDL

Causes Of Ankylosis:

• Trauma
• Infections
• Congenital
• Endocrinal disorders

Effects Of Ankylosis:

• Causes submerge of teeth
• Migration of adjacent teeth

Question 2. Abnormal labial frenum.
Answer.

• Abnormalities of maxillary labial frenum are quite often associated with maxillary midline spacing
• Rarely a heavy fibrous frenum is found attached to the interdental papilla region
• This can prevent the two maxillary central incisors
• Diagnosed by positive blanch test
• A midline IOPA or occlusal radiograph exhibits notching of the interdental alveolar crest

Question 3. Supernumerary teeth.
Answer.

Morphology: Different or resemble normal tooth (supplemental)

Size: Common in males

Site: Common in maxilla

Syndrome: Associated

• Cleidocranial dysplasia
• Gardener syndrome

Types Of Supernumeraty teeth:

• Mesiodens: Between central incisors
• Result: Midline spacing
• Distomolar: Beyond 3^rdmolar
• Paramolar: In region of molar

Causes Of Supernumerary teeth:

• Non-eruption of adjacent teeth
• Deflect eruption
• Crowding
• Risk of cyst formation

Question 4. Prolonged retention of deciduous teeth.
Answer.

• Prolonged retention of anterior teeth
  • Results in lingual or palatal eruption of their permanent successors
• Prolonged retention of posterior teeth
  • Results in eruption of permanent teeth either bucally or lingually or remain impacted

Question 5. Premature loss of deciduous teeth.
Answer.

• It refers to loss of a tooth before its permanent successor is sufficiently advanced in development and eruption to occupy its place
• It can cause migration of adjacent teeth into the place and can therefore prevent the eruption of the permanent successor
• Severity of malocclusion depends on
  • Premature loss of deciduous molars leading to shifting of adjacent teeth into space
  • Early extraction of deciduous teeth
  • Person with arch length deficiency and crowdling

Question 6. Prenatal causes of malocclusion.
Answer.

Prenatal causes of malocclusion:

• Abnormal fetal posture during gestation
• Maternal fibroids
• Amniotic lesions
• Maternal diet
• Maternal metabolism
• Maternal infections like German measles
• Teratogenic drugs

Question 7. Blanch Test.
Answer.

Use Of Blanch Test: For detection of high frenal attachment

Steps:

• Step 1: Upper lip is stretched
• Step 2: Upper lip is pulled outward and forward
• Step 3: Blanching seen beside the papilla
• Step 4: IOPA is taken i.r.t. 11 & 21

Etiology Of Malocclusion Viva Voce

• Early loss of deciduous teeth can cause migration of adjacent teeth into the space and thus prevent the eruption of permanent succesor
• Extra teeth in relation to the normal teeth is called supernumerary teeth
• Mesiodens are supernumerary teeth present between two central maxillary incisors
• Mesiodens are most common type of supernumerary teeth
• Supernumerary teeth present distal to the last molar is called distomolar
• Anamalous structure projecting from cingulum of maxillary permanent incisors is called Talon’s cusp
• Fusion occurs through union of two normally separated tooth gem
• Germination arises from division of single tooth germ
• Concrescence is fusion of teeth after completion of root formation
• Presence of notching and positive blanch test is diagnostic of abnormal thick labial frenum.

Classification Of Malocclusion Important Notes

Angle’s classification:

• Dewey’s modification:
  • Class 1 modifications:
    • Type 1 – Bunched/crowded interiors
    • Type 2 – Protursive maxillary anterior
    • Type 3 – Anterior crossbite
    • Type 4 – Posterior crossbite
    • Type 5 – Mesial drifting of permanent molar due to premature loss of 2nd deciduous molar
  • Class 3 modifications:
    • Type 1 – When upper and lower arches are viewed separately they appear normal
      • When a patient is made to occlude suggest forwardly placed mandibular dental arch
    • Type 2 – Mandibular incisors are crowded and in lingual relation to maxillary incisors
    • Type 3 – Maxillary incisors are crowded and in lingual relation to mandibular incisors
• Simon’s classification”
  • Described malocclusion in all the three planes
  • Frankfort Horizontal Plane:
    • Plane – Vertical
    • Extend – Upper margin of external auditory meatus to infra-orbital margin
    • Terminologies:
      • Attraction – When the dental arch is closer to the plane
      • Abstraction – When the dental arch is far away from the plane
  • Orbital plane
    • Plane – Horizontal
    • Extend – Perpendicular to Frankfort plane
    • From the bony orbital margin passes through a distal third of the upper canine “SIMON’s LAW OF CANINE”
    • Terminologies:
      • Protraction – Dental arch farther from the orbital plane
      • Retraction – Dental arch close to the orbital plane
  • Mid-Saggital Plane:
    • Plane – Transverse
    • Terminologies:
      • Distraction – The dental arch is away from the plane
      • Contraction – Dental arch close to the plane
• Ackermann Profitt classification:
  • Step 1 – Alignment:
  • Significance – Assessment of alignment and symmetry of dental arch
  • Classified into:
    • Ideal
    • Crowded
    • Spaced
  • Step 2 – Profile:
  • Involves:
    • Facial Profile
      • Straight
      • Convex
      • Concave
    • Facial divergence
      • Anterior
      • Posterior
  • Step 3 – Type:
    • Represents transverse dental and skeletal relationship

Involves:

• • Step 4 – Class:
    • Shows sagittal relationship
  • Involves:
    • A. Angles class 1 B. Skeletal
      • Class 2 – Dental
      • Class 3
  • Step 5 – Bite Depth:
    • Represents vertical relationship
  • Involves
    • Open bite
      • Anterior deep bite
      • Posterior collapsed bite
    • May be
      • Dental
      • Skeletal

Classification Of Malocclusion Long Essays

Question 1. Classify different malocclusions. Write a note on Angle’s classification of malocclusion.
Answer.

Classification Of Malocclusion:

Intra-arch Malocclusion:

• Includes variations in individual tooth position and affecting that of a group of teeth within an arch

Distal tipping: The crown of the tooth is tilted distally

Mesial tipping: The crown of the tooth is tilted mesially

Buccal tipping: The crown of the tooth is tilted labially

Read And Learn More: Orthodontics Short And Long Essay Question And Answers 

Palatal tipping: The crown of the tooth is tilted palatally

Mesial displacement: Bodily movement of the tooth is the mesial direction

Distal displacement: Bodily movement of the tooth is the distal direction

Buccal displacement: Bodily movement of tooth buccally

Lingual displacement: Bodily movement of tooth lingually

Infra occlusion: The tooth has not erupted enough as compared to other teeth in the arch

Supra occlusion: Tooth has over-erupted as compared to other teeth in the arch

Rotations: Tooth movement around its long axis

Disto-lingual/Mesio-buccal rotation: Movement of tooth around its long axis such that the distal aspect is more lingually placed

Mesio-lingual/Disto-buccal rotation: Movement of tooth around its long axis such that the mesial aspect is more lingually placed

Transposition: Two teeth have exchanged their places.

Inter-arch Malocclusion

Includes abnormal relationship between two teeth or groups of teeth of one arch to another arch.

• Sagittal Plane Malocclusion:
  • Pre-normal occlusion – Mandible is forwardly placed when the patient bites in centric occlusion
  • Post-normal occlusion – Mandible is distally placed when the patient bites in centric occlusion
• Vertical Plane Malocclusion:
  • Deep bite: Excessive overlapping of upper and lower anterior
  • Open bite: No overlapping between upper and lower anterior
• Transverse Plane Malocclusion:
  • Crossbite – Abnormal transverse relationship between upper and lower arches

Skeletal Malocclusion

Occur due to abnormalities in the maxilla/mandible

• Saggital Plane:
  • Prognathism – forwardly placement of the jaw
  • Retrognathism – backwardly placement of the jaw
• Transverse Plane:
  • Narrowing of jaw
  • Widening of jaw
• Vertical Plane:
  • Effecting lower facial height

Angle’s Classification of Malocclusion:

• Described by Edward H.Angle in 1899

Class 1:

• Mesio-buccal cusp of the maxillary first permanent molar occludes in the buccal groove of the mandibular first permanent molar
• Normal skeletal relation
• Normal muscle activity
• Presence of irregularities such as crowding, spacing, rotation, missing tooth, etc.

Bimaxillary protrusion:

• Molar relation is class 1
• Both arches are forwardly placed

Class 2:

• Disto-buccal cusp of upper first permanent molar occludes in the buccal groove of lower first permanent molar

Class 2, Division 1:

• Molar relation class 2
• Proclined upper incisor
• Increase in overjet
• Deep bite
• Abnormal muscle activity
• Upper lip hypotonic, short
• No lip seal formed
• Lip trap
• Narrowing of the maxillary arch
• Hyperactive mental activity and buccinators activity
• Convex facial profile
• Deep palate
• Increased lower facial height

Class 2, Division 2:

• Molar relation class 2
• Lingually placed upper central incisors
• Canines labially tilted
• Deep bite
• Square shaped arch
• Normal perioral muscle activity
• Backward path of closure
• Straight facial profile
• Decreased overjet
• Decreased facial height

Class 2, sub-division:

• Class 2 molar relation on one side of the arch and class 1 on the other side

Class 3:

• Mesio-buccal cusp of upper first molar occludes in interdental space between mandibular first and second molar
• Concave facial profile
• True class 3:
  • Genetic in origin
  • True Class Causes:
    • Large mandible
    • Forwardly placed mandible
    • Retro positioned maxilla
    • Small maxilla
    • Combination
  • True Class Features:
    • Lingually inclined lower incisors
    • Normal overjet/edge-to-edge/anterior crossbite
    • Narrow maxillary arch
• Pseudo Class 2:
  • Forward movement of the mandible during jaw closure
  • Pseudo-Class Causes:
    • Occlusal prematurities
    • Premature loss of deciduous posterior
    • Enlarged adenoids

Class 3 Subdivision:

• Class 1 molar relation on one side of the arch and class 3 on the other side

Limitations Of Malocclusion:

• Classification is done only in the antero-posterior plane
• 1st permanent molar is considered a fixed points
• Useless if 1st permanent molar is absent
• Does not differentiate between skeletal and dental malocclusion
• Does not highlight the etiology of malocclusion
• Individual tooth positions are not considered

Question 2. What are the six keys of normal occlusion and what are the basis, merits, and demeritsclassificationiof ficationthe malocclusion?
Answer.

By Andrew in 1970’sagittal

Key 1 – Molar interarch relationship:

• The mesiobuccal cusp of the upper first molar includes in groove between the mesial and medial buccal cusp of the lower first molar
• The mesiolingual cusp of the upper first molar should occlude in the central fossa of the lower first molar
• A distal marginal ridge of the upper first molar should occlude with a mesial marginal ridge of the lower second molar

Key – 2: Mesiodistal crown angulation:

• The gingival part of the long axis of clinical crown must be distal to the occlusal part of it.

Key – 3: Labio-Lingual Crown Inclination:

• If the gingival area of the crown is more lingually placed than the occlusal area – It is called Positive crown inclination
• If the gingival area of the crown is more labially placed than the occlusal area – It is called Negative crown inclination.
  • Positive – Maxillary incisors
  • Negative – Mandibular incisors, Maxillary and mandibular posteriors

Key – 4: Absence of Rotation

• There should not be any rotation of teeth
• Rotated posteriors – occupy more space
• Rotated interiors – occupy less space

Key 5 – Tight contacts:

• There should be tight contact between teeth

Key 6 – Curve of Spee:

• The curve of Spee should not exceed 1.5 mm

Key 7 – Bolton’s Analysis:

• Gives the mesiodistal width of maxillary and mandibular posteriors.

Angle’s Classification Of Malocclusion

Basis:

• Angle’s classification is based on the mesiodistal relation of the teeth, dental arches, and jaws
• According to Angle, the maxillary first permanent molar is key to occlusion
• Based on the relation of the lower permmsolarirst m solar to the upper first permanent molar, he classified malocclusion into three main classes: class 1, class 2, and class 3

Merits Of Malocclusion:

• It is simple to apply

Demerits Of Malocclusion:

• The classification cannot be considered in transverse and vertical plane
• Angle considered the first permanent molar as a fixed point in the skull but it is not so
• The classification cannot be applied if the first permanent molars are extracted or missing
• Classification cannot be applied to deciduous dentition
• The classification does not differentiate between skeletal and dental malocclusion
• It does not highlight the etiology of malocclusion
• Individual tooth malposition is not considered

Classification Of Malocclusion Short Essays

Question 1. Class 2 division 2.
Answer.

Class 2 Division 2

• Class 2 Division 2 is characterized by a class 2 molar relationship with reclined upper centrals that are overlapped by the lateral incisors
• Class 2 molar relation
  • The lower dental arch is distally positioned about the upper arch
  • The distobuccal cusp of the upper first molar occludes with the mesiobuccal groove of the lower first molar
• Class 2 canine relation
  • The distal incline of the upper canine occludes with the mesial incline of the lower canine
• Line of occlusion
  • The line of occlusion is altered
• Other clinical features
  • Molars in distocclusion
  • Retroclined central incisors and rarely other interiors as well
  • Deep bite
  • Broad square face with a pleasing straight profile
  • Backward path of closure
  • Deep mentolabial sulcus
  • Absence of abnormal muscle activity

Question 2. Class 2 division 1 versus Class 2 division 2.
Answer.

Class 2 Division 1 versus Class 2 Division 2

Question 3. Class 2 of Angle’s classification.
Answer.

Class 2 of Angle’s classification

• Disto-buccal cusp of upper first permanent molar occludes in the buccal groove of lower first permanent molar

Class 2, Division 1:

• Molar relation class 2
• Proclined upper incisor
• Increase in overjet
• Deep bite
• Abnormal muscle activity
• Upper lip hypotonic, short
• No lip seal formed
• Lip trap
• Narrowing of the maxillary arch
• Hyperactive mental activity and buccinators activity
• Convex facial profile
• Deep palate
• Increased lower facial height

Class 2, Division 2:

• Molar relation class 2
• Lingually placed upper central incisors
• Labially tilted upper lateral incisor
• Canines labially tilted
• Deep bite
• Square shaped arch
• Normal perioral muscle activity
• Backward path of closure
• Straight facial profile
• Decreased overjet
• Decreased facial height

Class 2, sub-division:

• Class 2 molar relation on one side of the arch and class 1 on the other side

Question 4. Class 3.
Answer.

Class 3

• Mesio-buccal cusp of upper first molar occludes in interdental space between mandibular first and second molar
• Concave facial profile

True Class 3 – Genetic In Origin

• Genetic In Origin Causes:
  • Large mandible
  • Forwardly placed mandible
  • Retro positioned maxilla
  • Small maxilla
  • Combination
• Genetic In Origin Features:
  • Lingually inclined lower incisors
  • Normal overjet/edge of edge/ anterior crossbite
  • Narrow maxillary arch

Pseudo Class 3:

Forward movement of the mandible during jaw closure

• Pseudo-Class Causes:
  • Occlusal prematuritires
  • Premature loss of deciduous posterior
  • Enlarged adenoids

Class 3 sub-division:

• Class 1 molar relation on one side of the arch and class 3 on the other side

Question 5. Dewey’s modification.
Answer.

Dewey’s modification

Dewey divided Angle’s class 1 into 5 types and class 3 into three types

Class 1 Modifications:

• Type 1: Bunched/crowded interiors
• Type 2: Protursive maxillary anterior
• Type 3: Anterior crossbite
• Type 4: Posterior crossbite
• Type 5: Mesial drifting of permanent molar due to premature loss of 2nd deciduous molar

Class 3 Modifications:

• Type 1: When upper and lower arches are viewed separately they appear normal
  • When a patient is made to occlude suggest forwardly placed mandibular dental arch
• Type 2: Mandibular incisors are crowded and in lingual relation to maxillary incisors
• Type 3: Maxillary incisors are crowded and in lingual relation to mandibular incisors

Question 6. Simnon’s classification.
Answer.

Simon’s classification

• By Simon
• Described malocclusion in all the three planes

Frankfort Horizontal Plane:

• Plane: Vertical
• Extend: Upper margin of external auditory meatus to infra-orbital margin
• Terminologies:
  • Attraction: When the dental arch is closer to the plane
  • Abstraction: When the dental arch is far away from the plane

Orbital plane:

• Plane: Horizontal
• Extend: Perpendicular to Frankfort plane
• From the bony orbital margin passes through a distal third of the upper canine “SIMON’s LAW OF CANINE”
• Terminologies:
  • Protraction: Dental arch farther from the orbital plane
  • Retraction: Dental arch close to the orbital plane

Mid-Sagittal Plane:

• Plane: Transerse
• Terminologies:
  • Distraction: The dental arch is away from the plane
  • Contraction: Dental arch close to the plane

Question 7. Venn Diagram/Ackemann Profit Classification.
Answer.

Venn Diagram

• Proposed by Ackeman and Profit in 1960

Venn Diagram Features:

• Consideration of vertical, transverse, and antero-posterior mal-relations
• Evaluations of crowding and arch symmetry
• Inclusion of incisor protrusion

Step 1 – Alignment:

Significance: Assessment of alignment and symmetry of dental arch

Classified into:

• Ideal
• Crowded
• Spaced

Step 2 – Profile:

Involves:

• Facial Profile:
  • Straight
  • Convex
  • Concave
• Facial divergence:
  • Anterior
  • Posterior

Step 3 – Type:

Represents transverse dental and skeletal relationship

Involves:

Step 4 – Class:

• Shows sagittal relationship

Involves:

• Angles class 1
  • Class 2
  • Class 3
• Skeletal
  • Dental

Step 5 – Bite Depth:

• Represents vertical relationship

Involves:

• Open bite
  • Anterior deep bite
  • Posterior collapsed bite
• May be
  • Dental
  • Skeletal

Question 8. Drawbacks of Angles Classification.
Answer.

Drawbacks of Angles Classification

• Classification is done only in the antero-posterior plane
• 1st permanent molar is considered a fixed points
• Useless if 1st permanent molar is absent
• Does not differentiate between skeletal and dental malocclusion
• Does not highlight the etiology of malocclusion
• Individual tooth positions are not considered

Classification Of Malocclusion Short Questions And Answers

Question 1. Skeletal Malocclusion.
Answer.

Skeletal Malocclusion

Occur due to abnormalities in the maxilla/mandible

• Sagittal Plane:
  • Prognathism – forwardly placement of the jaw
  • Retrognathism – backwardly placement of the jaw
• Transverse Plane:
  • Narrowing of jaw
  • Widening of jaw
• Vertical Plane:
  • Effecting lower facial height

Question 2. Pseudo Class 3.
Answer.

Synonyms Of Pseudo Class 3:

• Postural Class 3
• Habitual Class 3

Causes Of Pseudo Class 3:

• Deflection of mandible due to occlusal prematurities
• Forward movement of mandible due to premature loss of deciduous
• Forward movement of the mandible due to enlarged adenoids

Question 3. Clinical features of Class 2 division 2.
Answer.

Clinical features of Class 2 Division 2

• Molars in distocclusion
• Retroclined incisors and rarely other interiors as well
• Deep bite
• Broad square face with a pleasing straight profile
• Backward path of closure
• Deep mentolabial sulcus
• Absence of abnormal muscle activity

Question 4. Adenoid Facies.
Answer.

Adenoid Facies

• It is one of the causes of pseudo-class 3 malocclusion
• Adenoids are enlarged
• The tongue makes contact with it
• To prevent it the patient moves his mandible forward giving an appearance of class 3 malocclusion

Question 5. Lischer’s Classification of malocclusion.
Answer.

Lischer’s Classification of malocclusion

• Neutrocclusion: Synonymous with Angle’s class 1
• Distocclusion: Synonymous with Angle’s class 2
• Mesiocclusion: Synonymous with Angle’s class 3
• Buccocclusion: Buccal placement of tooth or group of teeth
• Lingocclusion: Lingual placement of tooth or group of teeth
• Supraocclusion: Teeth erupting beyond the normal level
• Infraocclusion: Teeth fail to erupt upto normal level
• Mesioversion: Mesial to normal position
• Distoversion: Distal to normal position
• Transversion: Transposition of teeth
• Axiversion: Abnormal axial inclination
• Torsiversion: Rotation of tooth

Question 6. Simon’s law of Canine.
Answer.

Orbital Plane Of Simon’s Classification:

• It is perpendicular to Frankfort’s horizontal plane
• It describes malocclusion in sagittal plane
• It is dropped down from the bony orbital margin directly under the pupil of the eye

Simon’s Law of Canine:

• According to Simon, the orbital plane should pass through the distal third of the upper canine
• This is called Simon’s law of canine

Question 7. Bennet’s Classification.
Answer.

Based On Etiology:

• Class 1: Abnormal position of one/more teeth due to local causes
• Class 2: Abnormal formation of a part/whole of either arch due to developmental defects of bone
• Class 3: Abnormal relationship between upper and lower arches and between either arch and facial contour and correlated abnormal function of either arch

Question 8. Simon’s classification.
Answer.

Simon’s classification

• By Simon
• Described malocclusion in all the three planes

Frankfort Horizontal Plane:

• Plane: Vertical
• Extend: Upper margin of external auditory meatus to infra-orbital margin
• Terminologies:
  • Attraction: When the dental arch is closer to the plane
  • Abstraction: When the dental arch is far away from the plane

Orbital plane:

• Plane: Horizontal
• Extend: Perpendicular to Frankfort plane
  • From the bony orbital margin passes through a distal third of the upper canine “SIMON’s LAW OF CANINE”
• Terminologies:
  • Protraction: Dental arch farther from the orbital plane
  • Retraction: Dental arch close to the orbital plane

Mid-Sagittal Plane:

• Plane: Transverse
• Terminologies:
  • Distraction: The dental arch is away from the plane
  • Contraction: Dental arch close to the plane

Classification Of Malocclusion Viva Voce

• Class 2 Division 1 exhibits abnormal muscle activity
• The upper arch is broad and narrow in class 2 division 2
• Class 2 Divisionthe  2 presents dolichocephalic facial formation
• Periodontal complications are very frequently seen in class 1 malocclusion
• Bimaxillary proclination and crowding are the most common forms seen in class 1 malocclusion
• Class 2 patients have a convex profile
• An increased curve of Spee is seen in class 2
• Abnormal buccinators activity is seen in class 2 division 1
• Class 3 is a progressive type of malocclusion
• A crowded upper arch and spaced lower arch are found in class 3 malocclusion.

Occlusion – Basic Concepts Definitions

• Centric relation
  • It is the relation of the mandible to the maxilla when the condyles are in the most superior and retruded position in their glenoid fossa with the articular disc properly interposed.
• Centric Occlusion:
  • It is that position of the mandibular condyle when the teeth are in maximum intercuspation
• Occlusion
  • It is the normal relation of the occlusal inclined planes of the teeth when the jaws are closed.
• Malocclusion
  • It refers to any deviations from normal occlusion
• Balanced occlusion
  • An occlusion in which balanced and equal contacts are maintained throughout the entire arch during all excursions of the mandible

Occlusion – Basic Concepts Important Notes

• Keys of occlusion
  • Molar interarch relationship
  • Mesiodistal crown angulation
  • Labio-lingual crown inclination
  • Absence of rotation
  • Tight contacts
  • Curve of Spee
  • Bolton’s ratio
• Curves of occlusion

Occlusion – Basic Concepts Short Essays

Question 1. Curves of Occlusion.
Answer.

The curve of Spee: It is antero-posterior curvature of the occlusal surfaces beginning at the tip of the lower cuspid and following the cusp tips of the bicuspids and molars continuing as an arch through the condyle

Value Of Occlusion: Forms a circle of 4-inch diameter

Significance Of Curve Of Spee: Shows axial alignment of lower teeth

• The long axis of each lower tooth is aligned parallel to its arc of closure around a condylar axis
• Gradual mesial tilting of teeth is seen

Curve Of Wilson:

• Contacts the buccal and lingual cusp tips of mandibular buccal teeth
• It is a mediolateral curve

Significance Of Curve Of Wilson:

• Provide resistance to masticatory forces
• Prevent food from going past the occlusal table

Curve Of Monson:

• Obtain by extending the curve of Spee and curve of Wilson to all cusps and incisal edges

Question 2. Arrangement of teeth.
Answer.

Cusp-Fossa Occlusion:

• The stamp cusp of one tooth occludes in a single fossa of a single opponent
• Upper stamp cusps fit into all except the mesial fossae of the lower teeth
• Lower stamp cusps fit into all the upper fossae except distal ones of bicuspids

Cusp-Embrasure Occlusion:

• Each tooth occludes with two opposing teeth

Read And Learn More: Orthodontics Short And Long Essay Question And Answers 

Question 3. Functional Occlusion.
Answer.

• It refers to tooth contacts that occur in the segment of the arch towards which the mandible moves
• Also called working side occlusion

Types Of Functional Occlusion:

Lateral Functional Occlusion:

• Tooth contacts occur on canines & posteriors on the working side.

Canine-guided occlusion:

• Working side
  • Upper & lower canine contact with each other
  • Disclusion of posteriors
• Balancing side
  • Disclusion of posteriors

Group Lateral:

• Canine guided occlusion
• Occlusion of certain posterior teeth occurs on the working side.

Protrusive Functional Occlusion

• Eccentric contacts occur during the forward movement of the mandible
• 6 mandibular anterior contact palatal inclines of maxillary anterior while posterior dis occlude.

Question 4. Centric relation and centric occlusion.
Answer.

Centric Relation:

Definition: It is the relation of the mandible to the maxilla when the condyles are in the most superior and retruded position in their glenoid fossa with the articular disc properly interposed.

Synonyms Of Centric Relation:

• Ligamentous position
• Terminal hinge position

Centric Occlusion:

Definition: It is the position of the mandibular condyle when the teeth are in maximum intercuspation

Synonyms Of Centric Occlusion:

• Inter-cuspal position
• Convenience occlusion

Significance Of Centric Occlusion:

• The perfect harmony between teeth, TMJ, and neuromuscular system
• Placement of mandible in an unstrained position

Acquired Occlusion:

• Maximum intercuspation obtained without condyles in centric relation

Synonyms Of Acquired Occlusion:

• Maximum intercuspation
• Habitual intercuspation

Question 5. Keys of Occlusion.
Answer.

By Andrew in the 1970’s

Key 1 – Molar interarch relationship:

• The mesiobuccal cusp of the upper first molar should occlude in the groove between the mesial and medial buccal cusp of the lower first molar
• The mesiolingual cusp of the upper first molar should occlude in the central fossa of the lower first molar
• A distal marginal ridge of the upper first molar should occlude with a mesial marginal ridge of lower of lower second molar

Key – 2: Mesiodistal crown angulation:

• The gingival part of the long axis of the clinical crown must be distal to the occlusal part of it.

Key – 3: Labio-Lingual Crown Inclination:

• If the gingival area of the crown is more lingually placed than the occlusal area – It is called positive crown inclination
• If the gingival area of the crown is more labially placed than the occlusal area – It is called Negative crown inclination
  • Positive – Maxillary incisors
  • Negative – Mandibular incisors, Maxillary and mandibular posteriors

Key 4: Absence of Rotation

• There should not be any rotation of teeth
• Rotated posteriors – occupy more space
• Rotated interiors – occupy less space

Key 5 – Tight contacts:

• There should be tight contact between teeth

Key 6 – Curve of Spee:

• The curve of Spee should not exceed 1.5mm

Key 7 – Bolton’s Analysis:

• Gives the mesiodistal width of maxillary and mandibular posteriors.

Occlusion – Basic Concepts Short Questions And Answers

Question 1. Define occlusion, balanced occlusion and malocclusion.
Answer.

Occlusion:

• By Angle
• It is the normal relation of the occlusal inclined planes of the teeth when the jaws are closed
• It is a complete phenomenon involving teeth, PDL, jaws, TMJ, muscles, and the nervous system

Balanced Occlusion:

• An occlusion in which balanced and equal contacts are maintained throughout the entire arch during all excursions of the mandible

Malocclusion:

• It refers to any deviations from normal occlusion

Question 2. Types of cusps.
Answer.

Centric Holding Cusps:

• Facial cusps of mandibular posteriors and
• Palatal cusps of maxillary posteriors are centric holding cusps.
• They occlude into the central fossa and marginal ridges of opposing teeth
• Also called “stamp cusps”

Non-Supporting Cusps:

• Buccal cusps of maxillary posteriors & Lingual cusps of mandibular posteriors are non-supporting cusps.
• Guides mandible during lateral excursions
• Shear food during mastication
• Also called shearing or guiding cusps

Question 3. Roth’s keys of functional occlusion.
Answer.

• Roth’s keys of functional occlusion are:
  • Key 1 – Coincidence of intercuspal position and retruded contact position
  • Key 2 – Maximum and stable cusp to fossa contacts throughout the buccal segments
  • Key 3 – Disclusion of the posterior teeth in mandibular protrusion by even contacts on the incisors
  • Key4 – Lateral movements of the mandible are guided by the working side canines with the disclusion of all the other teeth on both working and non-working sides

Question 4. Curve of Spee
Answer.

It is antero-posterior curvature of the occlusal surfaces beginning at the tip of the lower cuspid and following the cusp tips of the bicuspids and molars continuing as an arc through the condyle

Value: Forms a circle of 4-inch diameter

Significance: Shows axial alignment of lower teeth

• The long axis of each lower tooth is aligned parallel to its arc of closure around a condylar axis
• Gradual mesial tilting of teeth is seen

Occlusion – Basic Concepts Viva Voce

• Facial cusps of mandible and palatal cusps of maxillary posterior teeth are centric holding cusps
• Maxillary buccal and mandibular lingual cusps are non-supporting cusps
• Cusp fossa occlusion is tooth to tooth-to-tooth arrangement
• Cusp embrasure occlusion is tooth to two teeth arrangement
• The curve of Spee is antero-posterior curvature
• The curve of Wilson is mediolateral on each side
• The curve of Monsoon is obtained by extending the curve of Spee and the curve of Wilson
• Lateral functional occlusion is contact occurring on canines and posterior teeth on the side towards which the mandible moves
• Protrusive functional occlusion includes eccentric contact occurring when the mandible moves forward
• Disclusion of posterior teeth is brought about by condylar guidance and incisal guidance
• Andrew gave six keys to the occlusion
• According to Andrew curve of Spee should not exceed 1.5mm

Functional Development Important Notes

• Trajectories
  • Benningh described lines of stress as trajectories
  • Trajectories lines are:
  • In maxilla
    • Frontonasal buttress
    • Malar-zygomatic buttress
    • Pterygoid buttress
  • In mandible
    • Condyle to symphysis
    • Ramus through spongiosa
    • The lower border of the mandible
    • Mylohyoid ridges
• Wolff’s law of bone transformation
  • According to it, unlike other connective tissue, bone responds to mild degrees of pressures of pressure and tension by resorption of existing bone and deposition of new bone.

Functional Development Short Essays

Question 1. Muscles of mastication (or) Role of muscles of mastication.
Answer.

Question 2. Mastication.
Answer.

It is a complex activity aimed at breaking down and insalivation of the food, preparing to swallow.

Phases:

By Murphy

• Preparatory Phase:
  • Ingested food positioned towards the chewing side
  • Movement of the mandible to the same side
• Food contact:
  • Sensory receptors evaluate the viscosity of ingested food and load on the masticatory apparatus
• Crushing Phase:
  • Food is crushed equally by both arches
  • Starts with high velocity and gradually slows down
• Tooth contact:
  • End of crushing phase
  • Teeth are in contact with each other
• Guiding Phase:
  • Unilateral contact of teeth
• Centric occlusion:
  • Teeth come to a definite and distinct stop

Question 3. Infantile Swallowing.
Answer.

• Limited to breastfeeding
• Position of the tongue over lower gum pad protruding between lower lop and nipple
• Milk is directed to the pharynx by peristaltic movement of the tongue and mylohyoid
• Passage of milk between faucal pillars and lateral channels of pharynx

Features Of Infantile Swallowing:

• By Moyers
• Jaws are apart
• Tongue positioned between both the arches
• Stablilization of the mandible by contraction of muscle
• Controlled swallowing by nerve innervations

Period Of Infantile Swallowing:

• From breastfeeding till the child is used to semi-solid or solid food

Transformed To:

• Mature swallowing

Read And Learn More: Orthodontics Short And Long Essay Question And Answers 

Question 4. Mature swallowing.
Answer.

Age: 1 year

Phases:

• Preparatory swallow:
  • Features:
    • Placement of bolus over tongue
    • Jaws are apart
    • Contraction of cheek muscles
    • Stabilization of jaw
    • Teeth are occluded
    • Oral cavity is sealed when the posterior aspect of tongue is pressed against soft palate
• Oral phase:
  • Sealed nasal cavity by raising soft palate
  • Posterior portion of tongue is dropped down
  • Creation of smooth path for movement of bolus
• Pharyngeal phase:
  • Passage of food through facial pillars
  • Reflex of pharyngeal complex
  • The peristaltic movement of food
• Oesophageal phase:
  • Passage of food to cricopharyngeal sphincter
  • The peristaltic activity of oesophageal walls
  • Return of tongue and soft palate to their original position

Question 5. Deglutition.
Answer.

• Fletcher divided the deglutition pattern into four stages

Preparatory Swallow:

Features Of Preparatory Swallow:

• Placement of bolus over tongue
• Jaws are apart
• Contraction of cheek muscles
• Stabilization of jaw
• Teeth are occluded
• The oral cavity is sealed when the posterior aspect of the tongue is pressed against the soft palate

Oral Phase

• Sealed nasal cavity by raising the soft palate
• The posterior portion of the tongue is dropped down
• Creation of a smooth path for the movement of bolus

Pharyngeal Phase

• Passage of food through facial pillars
• Reflex of pharyngeal complex
• The peristaltic movement of food

Oesophageal Phase:

• Passage of food to cricopharyngeal sphincter
• Peristaltic activity of oesophageal walls
• Return of tongue and soft palate to their original position

Question 6. Buccinator Mechanism.
Answer.

Teeth and their supporting structures are blanketed from all directions by muscles.

• Thus relationship of teeth with each other and with that of the opposite arch is influenced by these muscles
• Oral cavity is surrounded by no.of muscles starting fibers of lop → muscles around the corner of mouth → buccinator muscle → pterygomandibular fibers → superior constrictor.

• The dento-alveolar region is surrounded by this band of muscle called buccinators mechanism
• Opposing this there is a very powerful muscular organ tongue
• Thus dentition is in constant equilibrium between the buccinator mechanism and the tongue

Question 7. Trajectories of force.
Answer.

It states that the lines of orientation of bony trabeculae corresponds to the pathways of maximal pressure and tension and that bone trabeculae are thicker in the region where the stress is greater

Trajectories Of Force

Classification: In Maxilla:

Vertical

• Fronto-nasal buttress

• Mala-Zygomatic

• Pterygoid buttress

From 2^nd & 3^rd molar

Horizontal:

• Hard palate
• Orbital ridges
• Zygomatic arches
• Palatal bone
• Lesser Wing of sphenoid.

In Mandible:

• Lower border of mandible
• Mylihyoid ridge

Question 8. Wolff’s law of Bone Transformation.
Answer.

• Bone responds to mild degrees of pressure and tension, by changes in its form
• It is achieved by means of resorption and deposition of bone

Sites Of Wolff’s law:

• Surface of bone under periosteum
• Surface of bony trabeculae
• On the wall of marrow spaces

Features Of Wolff’s law:

Bone is more plastic than any other tissue

“Bone is formed in just the quantity and shape that will enable it to with stand the physical demands made upon it, with the gretes amount of economy of structure”.

It is basis of Wolff’s law

• Not only the amount but the structure is also so formed that it enables the bone to withstand the forces exterted on it
• The structure of bone is such that it can best withstand the forcs acting on it

Functional Development Short Questions And Answers

Question 1. Muscles of mastication
Answer.

Functional Development Viva Voce

• Six stages of mastication are destribed by Murphy – Preparatory phase, food contact, crushing phase, tooth contact, guiding phase and centric occlusion
• Forms of deglutition/swallowing – infantile and mature
• Phases of deglutition – Preparatory, oral, pharyngeal and oesophagel
• Functional occlusion is also called working side occlusion
• Acquired occlusion is also called habitual occlusion.

Development Of Dentition And Occlusion Definitions

• Primate spaces/Simian spaces/Anthropoid spaces
  • These are spaces present mesial to the maxillary canines and distal to the mandibular canines
• Incisal liability
  • The difference between the amount of space needed for the accommodation of incisors and the amount of space available is called incisal liability.
• Leeway space of Nance
  • The differences between the combined mesiodistal width of deciduous canine and molars to the combined mesiodistal width of permanent canine and premolar is called the leeway space of Nance

Development Of Dentition And Occlusion Important Notes

• Gum Pads
  • These are alveolar processes present at the time of birth
  • They are developed in two parts – labiobuccal and lingual portion
  • Both parts are separated by a dental groove
  • Gum pads are separated into 10 segments by a transverse groove
  • The groove between the canine and first deciduous molar called lateral sulci determines inter arch relationship.
• The shift of lower molars from the flush terminal plane to class 1 occurs by
  • Early shift – by utilizing primate spaces
  • Late shift – by utilizing leeway space
• Transient maloccusions are
  • Open bite in gum pads
  • Deep bite
  • Spacing in deciduous dentition
  • Flush terminal plane
  • Ugly duckling stage
• Incisal liability is overcome by
  • Utilizing physiologic spaces
  • Increase in inter canine width
  • More labial inclination of permanent incisors
• Safety valve mechanism
  • An increase in inter-canine width is one of the important factors in overcoming incisal liability
  • At the age of 12, maxillary anterior prolines such that inter-canine width increase
• Significance:
  • This increase in maxillary intercanine width hinders the forward growth of the mandible
  • This increase in width behaves like it holds the forwardly growing mandible
• Maximum intercanine width occurs with the eruption of incisors
  • It is more in closed arches than in spaced arches

Read And Learn More: Orthodontics Short And Long Essay Question And Answers 

Development Of Dentition And Occlusion Long Essays

Question 1. Describe in detail the developmental periods of occlusion.
Answer.

Periods Of Occlusion Development:

Pre-dental period [after birth upto 6 neonates

Neonats do not have any teeth

• Gum Pads:
  • It is the alveolar process at the time of birth
  • Pink, firm covered by fibrous periosteum
  • Horseshoe shaped

Portions: labio-buccal and lingual – separated by a dental groove

• The transverse groove divides gum pads into 10 segments for 10 deciduous teeth
• Lateral sulcus present between canine and 1st deciduous molar
• Helps for interarch relationship

Upper Gum Pads: Longer and wider

Occlusion: Contact occurs between the upper and lower gum pads at the region of the first molar only. This facilitates sucking.

• Status of Dentition:
• Usually, no teeth are present at birth
• Teeth present at the time of birth – Natal teeth
• Teeth present during 1st month of age – Neonatal
• Both are located in mandibular incisor regions

Deciduous dentition period:

• Period – 6 months – 2 1/2 – 3 1/2 years
• The sequence of eruption – A – B – D – C – E
• SPACING – [Called Physiological spaces]
• Present mesial to maxillary canine and distal to mandibular canine
• Common in primates

Significance Of Periods Of Occlusion:

• Helps in the placement of canine cusps of the opposite arch
• Its absence leads to crowding
• Flush Terminal Plane:
  • Mesio-distal relation between the distal surfaces of upper and lower second deciduous molars is called the terminal plane
  • It lies in the same vertical plane
• Deep bite:
  • Due to the presence of more upright deciduous incisors
  • It overcomes by the following
    • Forward growth of the mandible
    • Attrition of incisors
    • Eruption of deciduous molars

Mixed dentition period:

• Age: 6 years of age
• Consists of: Both deciduous and permanent teeth

Phases:

First Transitional period:

• Emergence of first permanent molar:
  • At the age of 6 years
  • Its location depends upon the flush terminal plane
• Flush Terminal Plane:
  • Digital surfaces of upper and lower 2nd deciduous molars lie in the same vertical plane
  • Erupting 1st permanent molar forms end in relation
  • This is transferred to class 1 relation by the movement of the lower molar by 3-5 mm
  • Utilization of physiological spaces and leeway spaces

• • At the early stage of life By utilization of leeway space late shift
  • By utilization of physiological spaces
• Mesial Step terminal plane:
  • Here the distal surface of the lower deciduous 2nd molar is located mesial to that of the upper 2nd deciduous molar
  • Eruption of permanent molar occurs in class 1 relation
  • If further mandibular growth occurs, it leads to class 3 relation
• Distal step terminal plane:
  • The distal surface of the lower deciduous 2^ndmolar is located distal to that of the upper deciduous 2^nd molar
  • Eruption of permanent molar occurs in class 2 relation

Exchange of incisors:

• Exchange of deciduous incisors by permanent incisors
• Difference between the amount of space needed for accumulating permanent incisors and the amount of space that exists occurs
• This is called Incisor liability
  • Maxilla – 7mm
  • Mandible – 5mm

• Incisor liability is overcome by
  • Utilization of interdental spaces
  • Increase in inter-canine width
  • Change in incisor inclination
• Inter transitional period:
  • Consists of
    • Permanent incisors
    • Permanent first molars
    • Canines and deciduous molars

Second transitional period:

• It is the replacement of deciduous canines and molars by their permanent successors

Leeway space of Nance:

• The combined mesiodistal width of premolars and permanent canine is less than that of deciduous molars and canines
• This is called the Leeway space of Nance.
• Value: Maxillary arch – 1.8mm
  • Mandibular arch – 3.4mm

Significance Of Leeway Space of Nance:

• Utilization of this space during the late shift

Ugly Duckling Stage:

• Described by Broadbent
• Age – 8-9 years
• At the time of the eruption of canines

Stage Feature:

• As the permanent canine erupts, it pushes the root of the lateral incisor in turn pushes the root of the central incisor

Result Of Ugly Duckling Stage:

• Mesially displaced roots of incisors
• Distally displaced crowns of incisors
• Results in mid-line spacing

Significance Of Ugly Duckling Stage:

• It is a a self-correcting anomaly
• Corrected by the completion of the eruption of permanent canine
• Due to the transfer of force from the roots to the crowns

Permanent dentition period:

• Eruption sequence for both the arches
  6-1-2-4-3-5-7 or 6-1-2-3-4-5-7

Question 2. What are the stages of development of dentition? Write in detail about the self-correcting malocclusion
Answer.

Stages Of Development Of Dentition:

Pre-dental period [after birth upto 6 months]:

Neonates do not have any teeth

• Gum Pads:
  • It is the alveolar process at the time of birth
  • Pink, firm covered by fibrous periosteum
  • Horseshoe shaped

• Status of Dentition:
  • Usually, no teeth are present at birth

Deciduous dentition period:

• Period – 6 months – 2 1/2 – 3 1/2 years

Mixed dentition period:

• Age: 6 years of age
• Consists of: Both deciduous and permanent teeth

Phases:

First Transitional period:

• Emergence of first permanent molar:
  • At the age of 6 years
  • Its location depends upon the flush terminal plane
• Exchange of incisors:
  • Exchange of deciduous incisors by permanent incisors

Inter transitional period:

• Consists of
  • Permanent incisors
  • Permanent first molars
  • Canines and deciduous molars
• Stable period

Second transitional period:

• It is the replacement of deciduous canines and molars by their permanent successors

Permanent dentition period:

• Eruption sequence for both the arches
  6-1-2-4-3-5-7 or 6-1-2-3-4-5-7

Self-correcting malocclusion:

Development Of Dentition And Occlusion Short Essays

Question 1. Gum Pads.
Answer.

• It is the alveolar process at the time of birth
• Pink, firm covered by fibrous periosteum
• Horseshoe shaped

Portions Of Gum Pads:

• Labio-buccal and lingual – separated by a dental groove
• The transverse groove divides gum pads into 10 segments for 10 deciduous teeth
• Lateral sulcus present between canine and 1st deciduous molar
• Helps for interarch relationship

Upper Gum Pads:

• Longer and wider

Occlusion:

• Contact occurs between the upper and lower gum pads at the region of the first molar only. This facilitates sucking.

Question 2. Self Correcting anomalies
Answer.

Question 3. Broadbent phenomenon.
Answer.

• The ugly duckling stage was described by Broadbent
• Thus it is known as the Broadbent phenomenon

Ugly Duckling Stage:

• Described by Broadbent
• Age – 8-9 years
• At the time of the eruption of canines

Stage Feature:

• As the permanent canine erupts, it pushes the root of lateral incisors this in turn pushes the root of the central incisor

Result Of Ugly Duckling Stage:

• Mesially displaced roots of incisors
• Disatally displaced crowns of incisors
• Results in mid-line spacing

Significance Of Ugly Duckling Stage:

• It is a self-correcting anomaly
• Corrected by the completion of the eruption of permanent canine
• Due to the transfer of force from the roots to the crowns

Development Of Dentition And Occlusion Short Questions And Answers

Question 1. Physiological spacing.
Answer.

• Present mesial to maxillary canine and distal to mandibular canine
• Common in primates

Significance Of Physiological Spacing:

• Helps in the placement of canine cusps of the opposite arch
• Its absence leads to crowding

Question 2. Incisal liability.
Answer.

• Difference between the amount of space needed for accumulating permanent incisors and the amount of space that exists occurs
• This is called Incisor liability
  • Maxilla – 7mm
  • Mandible – 5mm
• Incisor liability is overcome by
  • Utilization of interdental spaces
  • Increase in inter-canine width
  • Change in incisor inclination

Question 3. Leeway space of Nance.
Answer.

• The combined mesiodistal width of premolars and permanent canine is less than that of deciduous molars and canines
• This is called the Leeway space of Nance.
• Value: Maxillary arch – 1.8mm
  • Mandibular arch – 3.4mm
• Significance Of Leeway Space of Nance: Utilization of this space during the late shift

Question 4. Late mesial shift.
Answer.

• Many children lack physiological spaces
• Thus erupting permanent molars are unable to move forward to establish a Class 1 relationship
• In these cases, when the deciduous second molars exfoliate the permanent first mol. ars drift mesially utilizing the leeway space
• This occurs in the late mixed dentition period
• Thus it is called late shift

Question 5. Enumerate the stages of tooth development.
Answer.

• The development of tooth was divided into 10 stages by Nolla as follows
• Stage 1 – Presence of crypt
• Stage 2 – Initial calcification
• Stage 3 – One-third of crown completion
• Stage 4 – Two-thirds of crown completion
• Stage 5 – Crown almost completed
• Stage 6 – Crown completed
• Stage 7 – One-third of the root completed
• Stage 8 – Two-thirds of the root completed
• Stage 9 – Root almost completed with open apex
• Stage 10 – Apical end of the root completed

Development Of Dentition And Occlusion Viva Voce

• The stages of tooth development are the bud cap and bell stage.
• Lateral sulci present between canine and deciduous first molar determine interact relation
• The mixed dentition period can be classified into 3 phases – first transitional, transitional, and second transitional.
• The first transitional period is characterized by the emergence of the first permanent molars and the exchange of deciduous incisors with permanent incisors
• Inter transitional period is relatively stable and no change occurs
• The second transitional period is characterized by the replacement of deciduous molars and canines by premolar and permanent canines
• Primate spaces help in the placement of canine cusps on the opposing arch
• Values

• Ugly duckling stage is transient malocclusion
• Primate spaces are utilized during the early medial shift of molars
• Initiation of primary dentition occurs in 6 weeks of IU life
• Broadbent coined the term ugly duckling stage
• Mandibular central incisors are the first tooth to erupt in primary dentition
• Nance determined the leeway space
• The ugly duckling stage is seen between 8-9 years

Growth And Development Of Cranial And Facial Region Important Notes

• Pre natal life is divided into
  • Period of ovum – 2 weeks from time of fertiliztion
  • Period of embryo – 2nd week to 8th week
  • Period of fetus – 9^thweek
• Branchial arch derivatives

• Remnants of Meckel’s cartilage
  • Mental ossicles
  • Incus and malleus
  • Anterior ligament of malleus
  • Sphenomandibular ligament
  • Spine of sphenoid
• Synchondroses – fusion of two adjacent bones by cartilages
  • Synostosis – early fusion of two adjacent bones by bone
  • Syndesmosis – fusion of two adjacent bones by fibrous ligament
• Ossification of synchondroses
  • Spheno occipital – at age of 18 years
  • Sphenoethamodial – by 5-25 years
  • Inter sphenoidal – at birth
  • Intra occipital – by 3-5 years

Growth And Development Of Cranial And Facial Region Long Essays

Question 1. Describe in detail about pre-natal growth of the maxilla.
Answer.

Formation Of Different Parts:

Oral Cavity: From stomodeum, which is a depression below the prominent bulge of fore brain

Lower lip: Through fusion of 2 mandibular processes

Cheek: From maxillary process

Read And Learn More: Orthodontics Short And Long Essay Question And Answers 

Nose: Frontonasal process, divides into medial and lateral nasal process

• Maxillary process fuses first with lateral nasal process and later medial nasal process and forms nasal placodes
• These sinks and forms nasal pits

Development Of Palate:

• Palatal shelves are given out from maxillary process
• These shelves grow medially
• Initially, these grows down to the tongue vertically
• Later, during 7th week of IU life, shelves turns upwards due to
  • Changes in bio-chemical and physical connective tissue
  • Changes in blodd supply
  • Appearance of intrinsic shelf force

• • Rapid differential miototic activity
  • Muscular movements
  • Withdrawal of the embryonic face from against the heart prominence

Fusion Of Palatal Shelves:

• At 8 1/2 weeks of IU life
• These are covered by epithelial lining
• Epithelial cells degenerate
• Connective tissue intermingle with each other resulting in their fusion
• Initially fusion occurs over central region forming secondary palate
• Fusion progresses both anteriorly and posteriorly
• Mesial edges fuse with lower end off nasal septum
• Thus palate is formed along with the separation of two nasal cavities with that of oral cavity

Question 2. Describe in detail the prenatal growth of mandible.
Answer.

• About 4^th week of IU life, pharyngeal arches are laid down on the lateral and ventral aspects of foregut.
• Separated by 4 branchial grooves
• First arch is called mandibular arch
• The mandibular processes of both sides grow towards each other and fuse in the mid line
• Results in formation of lower lip and lower jaw.

Meckel’s Cartilage:

• Around 41^st – 45^th day of IU life

• Mental ossicles
• Incus and Malleus
• Spine of Sphenoid
• Anterior ligament of malleus
• Spheno mandibular ligament

Condylar Process:

At 5th week of IU life

Coronoid Process:

Mental Region:

Question 3. Describe in detail, post natal growth of maxilla.
Answer.

Post Natal Growth Of Maxilla:

• Mechanism involved in it

Displacement:

• Secondary displacement: Growth of maxilla occurs in downward and forward diretion due to growth of middle cranial fossa
• Primary displacement: Growth of maxilla occurs in forward direction due to growth of maxillary tuberosity in posterior direction.

Growth At Sutures:

Sutures involved are

• Fronto-nasal
• Fronto-maxillary
• Zygomatico-temporal
• Zygomatico-maxillary
• Pterygo-palatine

Surface Remodeling

• Growth of bone occurs due to the relative deposition and resorption of different parts
• This occurs in a balanced fashion

Question 4. Define growth and development explain post natal growth of mandible. Describe in detail post natal growth of mandible.
Answer.

Growth And Development Of Cranial And Facial Region Short Essays

Question 1. Synchondrosis.
Answer.

• Usually cartilage is replaced by bone
• But at the margins of junction of various bones, there is presence of bands of cartilages
• These are called “Synchondrosis”

Types Of Synchondrosis:

Spheno-occipital Synchondrosis:

• Bones involved: Sphenoid and Occipital
• Active: At 12-15 years of age
• Fusion: AT 20 years of age

Significance:

• Provides pressure adapted bone growth
• Carriers anterior part of cranium forwards

Spheno-ethmoid Synchondrosis:

• Bone involved: Sphenoid and ethamoid
• Ossification: 5-25 years of age

Inter-sphenoidal Synchondrosis:

• Between 2 sphenoid bones
• Ossify at birth

Intra-occipital Synchondrosis: Ossify at 3-5 years of age

Question 2. Spheno-occipital synchondrosis.
Answer.

Synchondrosis

• Synchondrosis are defined as the bands of cartilage present at the junction of various bones during the bone formation
• These synchondrosis form important growth sites in the base of skull

Types Of Spheno-occipital

• Spheno-occipital
• Intersphenoidal
• Intraoccipital
• Sphenoethamoidal

Spheno-Occipital Synchondrosis:

• Bones involved: Sphenoid and Occipital
• Active: At 12-15 years of age
• Fusion: At 20 years of age

Significance Of Spheno-occipital synchondroses:

• Spheno-occipital Synchondroses are responsible for most of the lengthening of cranial base between foramen magnum and sella turcica
• It is major contribution of endochondral growth till 20 years
• Elongation of synchondroses in combinatin with drift and remodeling contribute to cranial base lenghthening

Question 3. Growth of cranial base
Answer.

• Growth of cranial base occurs during 4^th– 8^th week of IU life
• During this there is condensation of mesenchymal tissue derived from the primitive streakm neural cresr and occipital sclerotomes around the developing brain
• A capsule is formed around brain calledectomenix that gives rise to future cranial base
• From around 40^th day the capsule is slowly converted to cartilage

Conversion Of Mesenchymal Cells Into Cartilage:

• It occurs in 4 regions

Chondro Cranial Ossification:

• Cartilages of cranial base now undergoes ossification
• It undergoes both intramembranous and endochondral ossification

Occipital bone:

• Shows both type of ossification
• Seven ossification centres are seen – 2 intramembranous and 5 endochondral

Temporal bone:

• Ossifies from 11 centres

Ethmoid bone:

• Shows only endochondral ossification
• Has three ossification centres
  • One-located centrally, forms medial floor of the anterior cranial fossa
  • Two-located bilaterally in nasal capsule

Sphenoid bone:

• Ossifies both intramembranously and endochondrally
• Have atleast 15 ossification centres

Nature Of Growth

• Growth of cranial base is highly uneven
• Anterior and posterior part grow at different rates
• Between 10th – 40th week of IU life, growth
• Anterior part – increases 7 times
• Posterior part – Increases 5 times

Growth And Development Of Cranial And Facial Region Short Questions And Answers

Question 1. Remnants of Meckel’s cartilage.
Answer.

• Mental ossicles
• Incus and Malleus
• Spine of sphenoid
• Anterior ligament of malleus
• Spheno-mandibular ligament

Question 2. Sutures involved in post-natal growth of maxilla.
Answer.

• Fronto-nasal suture
• Fronto-maxillary suture
• Zygomatico temporal suture
• Zygomatico maxillary suture
• Pterygo palatine suture

Question 3. Butler’s field theory.
Answer.

• The human dentition is divided into four fields: incisor, canine, premolar and molar
• The most distal tooth in each field is the most susceptible to changes or variations which include absence of tooth, variation in size, shape and structure
• This is called Butler’s field theory
• Ex – lateral incisors, second premolars and third molars are most variable in this group
• Canine is the least variable in their group
• Butler’s field theory does not apply in lower anterior region, where mandibular central incisor is more commonly missing than lateral incisor

Growth And Development Of Cranial And Facial Region Viva Voce

• Mandible grows in length by resorption at the anterior border and bone deposition at posterior border of ramus
• A single ossification center occurs for each half of mandible
• Maxilla has three ossification centres: one for maxilla proper and remaining two for pre maxilla.
• Mandible ossification centre is present in area of future mental foramen.
• Maxilla ossification centre is present in infraorbital foramen.
• Mandibular condyle is the only bone that shows both apposition and interstitial growth
• Sphenomandibular ligament extends from lingula to spine of sphenoid
• Congenital defects can occurs during period of embryo of prenatal life.
• Embryo proper is mainly formed by inner cell mass or embryoblast
• Branchial arches are formed by 4th week of IU life
• Development of face starts by 4-8 week.
• Development of palate occurs by 6-9 weeks.
• Development of tongue occurs by 4th week
• Development of maxillary sinus occur by 3rd month
• primary palate is derived from frontonasal process
• Secondary palate is derived from two palatal shelves and nasal septum
• Tongue is derived from tuberculumimpar, two lingual swellings and hypobranchial eminence.
• Meckel’s cartilage is primary cartilage of first arch.
• Reichert’s cartilage is primary cartilage of second arch
• Mandible develops develops as intramembranous bone
• At birth skull consists of 45 bones which later ossifies to 22 bones.

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Growth And Development General Principles And Concepts Definitions

• Growth
  • By Todd – An increase in size
  • By Moyers – Quantitative aspect of biologic development per unit time
• Development
  • According to Todd, development is progress towards maturity.
• Differential growth
  • It means different organs grow at different rates, to different amounts, and at different times.
• Growth spurts
  • A sudden increase in growth is called a growth spurt.

Growth And Development: General Principles And Concepts Important Notes

• Timings of growth spurts
  • Just before birth
  • One year after birth
  • Mixed dentition growth spurts
    • Boys – 8-11 years
    • Girls – 7-9 years
  • Pre-pubertal growth curve
    • Boys- 14-16 years
    • Girls – 11-13 years
• Scammon’s growth curve

• Cephalo casual gradient of growth
  • Growth of head
    • During the third month of intrauterine life – 50% of the total body length
    • At birth – 30% of total body length
    • During adulthood – 12% of total body length
    • Growth of lower limbs
    • During the second month of intrauterine life – rudimentary
    • During adulthood – 50% of body length
• Radio isotopes used for the study of growth are technetium 33, calcium 45, and potassium 32.
• Drift and displacement
  • Drift
  • The combination of deposition and resorption occurring in different bones of the skull resulting in growth movement towards the depositary surface is called drift.
  • Displacement – It is the movement of whole bone as a unit
• Bone formation
  • Endochondral bone formation

• • Intra-membranous bone formation

• Theories of growth
  • Genetic theory
  • Sutural theory – by Sicher
  • Cartilaginous theory – By James Scott

Read And Learn More: Orthodontics Short And Long Essay Question And Answers 

• • Functional matrix theory – By Melvin Moss
  • Van Limborgh’s theory – By Von Limborgh
• Functional matrices
  • Functional matrix:
  • Consists of muscle, glands, nerves, vessels, fat, teeth, and functional spaces
  • Divided into
  • Periosteal matrices

• • Capsular matrices
    • Acts indirectly and passively on bone
    • Expansion of capsule
    • Results growth of bones within it

Ex: Growth of facial bones due to expansion of oro-facial capsule

Growth And Development: General Principles And Concepts Long Essays

Question 1. Enumerate theories of growth explain functional matrix theory
Answer.

Growth:

It is defined as

• By Todd – An increase in size
• By Moyers – Quantitative aspect of biologic development per unit time
• By Meridith – Entire series of sequential anatomic and physiologic changes taking place from the beginning of prenatal life to senility

Theories Of Growth:

• Genetic theory
• Cultural theory – by Sicher
• Cartilaginous theory – By James Scott
• Functional matrix theory – By Melvin Moss
• Van Limborgh’s theory – By Von Limborgh

Functional Matrix Concept:

• Melvin Moss combined sutural theory and cartilaginous theory and introduced this concept

Hypothesis:

• It claims that the origin, form position, growth and maintenance of all skeletal tissues and organs are always secondary, compen-satory and necessary responses to chronologically and morphologically prior events or processes that occur in specifically related non-skeletal tissues, organs or functioning spaces

Components Of Growth:

• Skeletal Unit:
  • Microskeletal
  • Macroskeletal
• Functional Matrix:
  • Periosteal Matrices
    • It includes muscles, blood vessels, nerves and glands
  • Capsular Matrices
    • It includes neurocranial capsule and orofacial capsule
    • Neurocranial capsule is made up of skin, connective tissue, aponeuritic tissue, loose connective tissue, periosteum and two layers of duramater
    • Orofacial capsule surrounds and protects the oro-nosopharyngeal spaces which constitutes the orofical capsular matrix

Skeletal Unit:

• All skeletal tissues associated with a single function are called the skeletal unit
• When a bone is comprised of several contagious skeletal units, it is termed as “Micro skeletal units” Ex. Maxilla, Mandible
• When adjoining portions of a number of neighbouring bones are united to function as a single cranial component, termed as “macro skeletal unit” Ex. Calvarium

Functional Matrix:

• Consists of muscle, glands, nerves, vessels, fat, teeth and functional spaces
• Divided into

Periosteal matrices:

Capsular matrices:

• Acts indirectly and passively on bone
• Expansion of capsule
• Results growth of bones within it

Ex: Growth of facial bones due to expansion of oro-facial capsule

Growth And Development: General Principles And Concepts Short Essays

Question 1. Clinical application of growth and development.
Answer.

Clinical Application Of Growth And Development Includes:

• Growth Pattern:
  • It can be defined as proportional relationship over time
  • The patterns are controlling or restricting mechanisms to preserve the integration of parts of the body under varying conditions
• Differential growth:
  • It means different organs grow at different rates, to a different amount and at different times.
  • It is explained by two concepts namely – Scammon’s growth curve and Cephalocaudal gradient of growth

Scammon’s growth curve:

• It explains the growth of four different tissues – Lymphoid tissue, neural tissue, general tissue and genital tissue

Cephalocaudal gradient of growth:

• Represents axis of increased growth extending from head towards feet

Variability of growth:

• No two individuals are alike
• No two individuals grow in the same pattern
• Causes for it are
  • Hereditary
  • Nutrition
  • Racial differences
  • Climate
  • Exercise
  • Socioeconomic class
  • Psychological factors
  • Size of family
  • Hormonal changes
  • Sex differences
  • Growth spurts
• Timing variation in growth:
  • Growth does not take place uniformly at all times
  • There are certain periods when a sudden acceleration of growth occurs
  • This sudden increase in growth is termed as growth spurt
• Safety valve mechanism:
  • It is maintain proper occlusion
  • To compensate for the horizontal growth in mandible, the maxillary intercanine width serves as safety value

Question 2. Growth spurts.
Answer.

A sudden increase in growth is called growth spurts

Causes Of Growth Spurts:

• Hormonal secretion

Timings:

Just before birth:

• One year after birth
• Mixed dentition stage
  • Boys – 8-11 years
  • Girls – 7-9 years
• Pre-pubertal growth spurts
  • Boys – 14-16 years
  • Girls – 11-13 years

Significance Of Growth Spurts:

• Differs in boys and girls
• Effects the treatment planning
• During growth spurts – Myofunctional appliances are used
• After cessation of growth spurts – urgical correction
• During pubertal growth spurts there is change in growth direction form vertical to horizontal
• Periods of maximum growth are suitable for arch expansion and rapid skeletal expansion procedures
• Growth spurt period is best time for interceptive orthodontic procedures

Question 3. Micro-implants.
Answer.

• Introduced by Bjork in 1969
• Involves implanting inert alloys into growing bone
• Radiographs are taken

Size Of Implants:

• 1.5mm in length
• 0.5mm in diameter

Material:

• Tantalum

Sizes In Maxilla:

• Behind deciduous canines
• Below anterior nasal spine
• Two on either side of zygomatic process
• Border between hard palate and alveolar process medial to first molar

Sites In Mandible:

• Anterior aspect of symphysis
• Two pins on right side of body
• One pin on external aspect of right ramus at the level of occlusal surface

Question 4. Differential growth.
Answer.

Differential Growth:

It means different organs grow at different rates, to a different amount and at different times.

Concepts:

Scammon’s growth curve:

• It explains the growth of four different tissues

Lymphoid tissue:

• Childhood – 20% of adult size
• Adult – Involution
• Significance – Increase during childhood helps to adapt for protection against infections

Neural tissue:

• 6-7 years – Adult size
• After – Little growth
• Significance – Facilities intake of further knowledge

General tissue:

• Until puberty – negligible growth
• At puberty – grow rapidly

Cephal – Caudal growth curve:

• Represents axis of increased growth extending from head towards feet

Examples:

Question 5. Methods of Studying growth.
Answer.

• Approaches:
  • Measurement: Carried on humans
  • Experimental: Carried on animals
• Experiments:
  • Biometric test:
    • Standard measurements regarding height, weight, ossification are compared
  • Vital staining:
    • By Belchier
    • He identified alizarin from madden plants and used it for research

Technique:

Dyes used:

• Alizarin red 5
• Acid Alizarin Blue
• Trypon Blue
• Tetracycline
• Lead acetate

Radioisotope:

• Inject radiosotope into tissue
• This gets incorporated into bone
• Act as vivo markers

Used:

• Technetium – 33
• Calcium – 45
• Potassium – 32

Implants:

• Introduced by Bjork in 1969
• Involves implanting inert alloys into growing bone
• Radiographs are taken

Size of implants:

• 1.5mm in length
• 0.5mm in diameter

Material:

• Tantalum

Sites in Maxilla:

• Behind deciduous canines
• Below anterior nasal spine
• Two on either side of zygomatic process
• Border between hard palate and alveolar process medial to first molar

Sites in mandible:

• Anterior aspect of symphysis
• Two pins on right side of body
• One pin on external aspect of right ramus at the level of occlusal surface

Radiographic techniques:

• Radiographs used
• Cephalometry
• Hand wrist

Natural Markers:

• Nutrient canals, lines of arrested growth and prominent trabeculae these are considered as natural markers

Use: To study bone deposition, resorption and bone remodeling

Question 6. Osteogenesis.
Answer.

It is the process of bone formation

Types Of Bone Formation:

Endochondral bone formation:

Intra-membranous bone formation:

Question 7. Enumerate theories of growth explain functional matrix theory.
Answer.

Theories Of Growth:

• Genetic theory
• Sutural theory – by Sicher
• Cartilagenous theory – By James Scott
• Fuctional matrix theory – By Melvin Moss
• Van Limborgh’s theory – By Von Limborgh

Functional Matrix Concept

• Melvin Moss combined sutural theory and cartilaginous theory and introduced this concept

Hypothesis:

• It claims that the origin, form, position, growth and maintenance of all skeletal tissues and organs are always secondary, compensatory and necessary responses to chronologically and morphologically prior events or processes that occur in specifically related non-skeletal tissues, organs or functioning spaces

Components Of Hypothesis:

• Skeletal unit:
  • Microskeletal
  • Mactroskeletal
• Functional Matrix:
  • Periosteal Matrices
  • Capsular Matrices

Skeletal Unit:

• All skeletal tissues associated with a single function are called the skeletal unit
• When a bone is comprised of several cotagious skeletal units, it is termed as “Micro skeletal units” Ex. Maxilla, Mandible
• When adjoining portions of a number of neighbouring bones are united to function as a single cranial component, termed as “Macro skeletal unit” Ex. Calvarium

Functional Matrix:

• Consists of muscle, glands, nerves, vessels, fat, teeth and functional spaces
• Divided into

Periosteal matrices:

Capsular matrices:

• Acts indirectly and passively on bone
• Expansion of capsule
• Results growth of bones within it

Ex. Growth of facial bones due to expansion of oro-facial capsule

Question 8. Van Limborgh’s Theory.
Answer.

• By Van Limborgh in 1970
• He combines all the three existing theories
• He supports the functinal matrix theory of Moss, some aspects of Sicher’s theory and genetic theory
• He suggested 5 factors to control growth

Intrinsic Genetic factors: Genetic control of the skeletal units

Local Epigenetic factors: Genetic control originating from adjacent structures

General Epigenetic factors: Genetic control originating from distant structures

Local Environmental factors: Non-genetic factors from local external environment

General Environmental factors: General non-genetic influences

Examples:

Question 9. Enlow’s principle.
Answer.

Enlow’s expanding V principle:

• Explains bone remodeling of facial bones
• Growth and enlargement of bones occurs as a result of selective deposition and resorption

Deposition: Inner side of wide end of ‘V’

• At the ends of arms of ‘V’

Resorption: On the outer surface

Regions: Base of mandible

• Ends of long bone
• Mandibular body, palate etc,

Enlow’s Counter part principle:

• It states that the growth of any given facial or cranial part relates specifically to other structural and geometric counter part in the face and cranium
• If each regional part and its particular counter part enlarge to the same extent, balanced growth occurs.

Question 10. Neutrophism/Neurotrophic theory.
Answer.

It is a non-impulse transmitting neural function that involves axoplasmic transport and provides for long term interaction between neurons and innervated tissues that homeostatically regulates the morphological compositional and functional integrity of tissues.

Types Of Neurotrophic theory:

Neuro-epithelial trophism:

Neuro muscular trophism: At the myoblastic stage of differentiation, neural innervations is established

Neuro-Visceral trophism: Salivary glands, fat tissue and other organs are trophically regulated

Question 11. Scammon’s Growth Curve.
Answer.

It explains the growth of four different tissues

Lymphoid Tissue:

• Childhood – 20% of adult size
• Adult – Involution
• Significance – Increase during childhood helps to addapt for protection against infections

Neural Tissue:

• 6-7 years – Adult size
• After – Little growth
• Significance – Facilities in take of further knowledge

General Tissue:

• Exhibits ‘S’ shaped curve
• 2-3 years – rapid growth
• 3-10 years – slow growth
• Upto 18-20 years – rapid growth

General Tissue:

• Until puberty – negligible growth
• At puberty – grow rapidly

Question 12. Functional matrix theory
Answer.

Functional Matrix Concept:

• Melvin Moss combined sutural theory and cartilaginous theory and introduced this concept

Hypothesis:

• It claims that the origin, form, position, growth and maintenance of all skeletal tissues and organs are always secondary, compensatory and necessary responses to chronologically and morphologically prior events or processes that occur in specifically related non-skeletal tissues, organs or functioning spaces

Components Of Functional matrix:

• Skeletal Unit:
  • Microskeletal
  • Macroskeletal
• Functional Matrix:
  • Periosteal Matrices
  • Capsular Matrices

Skeletal Unit:

• All skeletal tissues associated with a single function are called the skeletal unit
• When a bone is comprised of several contagious skeletal units, it is termed as “Micro skeletal units”
• When adjoining portions of a number of neighbouring bones are united to function as a single cranial component, termed as “Macro skeletal unit” Ex. Calvarium

Functional Matrix:

• Consists of muscle, glands, nerves, vessels, fat, teeth and functional spaces
• Divided into

Periosteal matrices:

Capsular matrices:

• Acts indirectly and passively on bone
• Expansion of capsule
• Results growth of bones with in it

Ex. Growth of facial bones due to expansion of oro-facial capsule

Question 13. Cartilaginous theory of growth.
Answer.

• Cartilaginous theory was put forward by James Scott
• According to him intrinsic growth factors are present in cartilage and periosteum with sutures being secondary
• Nasal septal cartilage is considered to be pacemaker for the growth of entire naso-maxillary complex
• Mandible is considered as diaphysis of long bone
• This theory was supported due to following observations:
  • In many bones cartilage growth replaces bone
  • If a part of an epiphyseal plate is transplated to a different location it will continue to grow in the new location
  • Nasal septal cartilage shows innate potential of growth
  • In rabbits removal of nasal septal cartilage showed retarded mid face development

Growth And Development: General Principles And Concepts Short Questions And Answers

Question 1. Neurotrophic theory.
Answer.

It is a non-impulse transmitting neural function that involves axoplasmic transport and provides for long term interation between neurons and innervated tissues that homeostatically regulates the morpho-logical compositional and functional integrity of tissues.

Types Of Neurotrophic:

• Neuro-epithelial trophism
• Neuro-muscular trophism
• Neuro-Visceral trophism

Question 2. Define Growth.
Answer.

• An increase in size – Todd
• Entire series of sequential anatomic and physiologic changes taking place from the beginning of prenatal life to seenlity – By Meridith

Question 3. Development.
Answer.

Development is progress towards maturity.

According To Todd:

• According to Moyers, development refers to all the naturally occuring unidirectional changes in the life of individual from its existence as a single cell to its elaboration as a multi functional unit terminating in death.

Question 4. Enumerate factors effecting growth.
Answer.

• Hereditary
• Nutrition
• Illness
• Race
• Socio-economic
• Family size and birth order
• Secular trends
• Climatic and seasonal effects
• Psychological disturbances
• Exercise

Question 5. Natural markers.
Answer.

Nutrient canals, lines of arrested growth and prominent trabeculae these are considered as natural markers

Uses of Natural markers: To study bone deposition, resorption and bone remodeling

Question 6. Enumerate theories of growth.
Answer.

Theories Of Growth.

• Genetic theory
• Sutural theory – by Sicher
• Cartilagenous theory – By James Scott
• Functional matrix theory – By Melvin Moss
• Van Limborgh’s theory – By Von Limborgh

Question 7. Displacement.
Answer.

It is the movement of the whole bone as a unit

Types Of Displacement:

Primary Displacement:

• When bone gets displaced as a result of its own growth
  Ex. Displacement of maxilla due to growth at its tuberosity region

Secondary Displacement:

• When bone gets displaced as a result of growth and enlargement of its adjacent bone
  Ex. Displacement of maxilla due to growth of cranial base

Question 8. Differential growth.
Answer.

• It means different organs grow at different rates, to a different amount and at different times.
• It is explained by two concepts namely – Scammon’s growth curve and Cephalocaudal gradient of growth
  • Scammon’s growth curve
    • It explains the growth of four different tissues Lymphoid tissue, neural tissue, general tissue and genital tissue
  • Cephalocaudual gradient of growth

Growth And Development: General Principles And Concepts Viva Voce

• In Scammon’s growth curve, S shaped curve indicates growth of muscles and bone tissues, genital tissues shows negligible growth upto puberty.
• Implants and vital staining techniques are used to study dynamic changes of growth, radiographs shows static changes
• Arthropometry is the measurement of skeletal dimensions on living individuals
• The adult human body contains 206 bones, 33 vertebrae, 12 pairs of cranial nerves, 31 pairs of spinal nerves, 12 pairs of rib.
• Stains used in vital staining are Alizarin, trypton blue, tetracycline, lead acetate.