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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.

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.

Expansion

• Types of expansion appliances

• Rapid maxillary expansion [RME]
  • Should be initiated prior to ossification of the mid-palatal suture
  • Time of ossification of mid-palatal suture
    • 16 years – in girls
    • 18 years – in boys
• Contraindication of RME
  • Single tooth crossbites
  • In adults with severe anteroposterior skeletal discrepancies
  • Vertical growers
  • Periodontally weak condition
• Schedule of activation of expansion screw
  • For patients upto 15 years – 90° rotation in morning and evening
  • For patients over 15 years – 45° rotation 4 times a day
• Quad helix
  • Uses:
    • Expand a narrow arch
    • Rotation of molars
    • Brings
      • Orthopaedic movement in children
      • Orthodontic movement in adults

Expansion Long Essays

Question 1. Explain slow and rapid expansion, their indications, contraindications, and appliances used.
Answer.

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

Effects Of Rapid Maxillary Expansion:

• Open mid-palatal suture:
  • By compresses PDL
  • Bends buccal alveolar process and slowly opens the suture
• Triangular opening:
  • Maximum opening at incisor region
  • Reduces over posterior part of palate

• • Maximum opening towards oral cavity
  • Less opening towards nasal aspect
• Midline diastema
• Buccal tipping of maxillary posteriors

• Downward and backward mandibular rotation
• Increase in mandibular plane angle
• Displacement adjacent cranial bones
• Increase in intra-nasal space
• Reduction in airway resistance

Expansion Short Essays

Question 1. Expansion screws.
Answer.

• A typical expansion screw consists of an oblong body with two halves, each half consisting of threaded inner side that receives one end of a double-ended screw
• The screw has a central basing with four holes, which receive a key used to turn the screw
• The turning of screw to 90 degrees brings about linear movement of 0.18mm
• Various types of expansion used in removable and fixed appliances are
  • Jackscrew
  • Coffin springs
  • Qual helix
  • Isacson
  • Hyrax
  • Derischweiler
• Activation schedules

According to Timms:

• In patient upto 15 years of age – 90 degrees rotation in the morning and evening
• In patient over 15 years old – 45 degrees activation 4 times a day

According to Zimring and Isacson:

• In growing individuals
  • Two turns each day for 4-5 days and later one turn per day till the desired expansion is achieved
• In non-growing adults
  • Two turns each day for first 2 days and later one turn per day for next 5-7 days and one turn every alternate day till the desired expansion is achieved

Question 2. Quad Helix Appliance.
Answer.

Example of slow maxillary expansion appliance

Introduced by Walter coffin

• Wired used: 0.038 inch
  • Parts
• Bands: Over first molar
• Helices: 2 anteriors helices
  • 2 posterior helices
• Bridge: Anterior bridge – Connencts anterior helices
• Palatal bridge: Connects anterior and posterior helices
• Outer arms: Free ends adjacent to posterior helices
  • Soldered on lingual aspect of molar bands
• Uses: Expansion of narrow arch
  • Rotation of molars
• Skeletal expansion: During mixed dentition periods
• Activation: Pre-stretching of molar bands before cemenstation.

Question 3. Rapid v/s slow expansion.
Answer.

Expansion Short Questions And Answers

Question 1. Hyrax Appliance.
Answer.

Tooth bone fixed appliances used for rapid maxillary expansion

Hyrax – Hygienic rapid expander

Designs Of Hyrax Appliance:

• Wire used – Heavy guage wire
• Extensions of screw wire are adapted over palatal contour and soldered to molar bonds

Question 2. Coffin Spring.
Answer.

• Removable slow expansion appliance by Walter Coffin
• Wire used: 1.25 mm thick
• Design: Omega shaped wire – Over mid-palatal region
• Free ends of wire: Embedded in acrylic
• Activation: Pulling two sides apart
• Use: Dento-alveolar expansion in adults
• Skeletal expansion in younger patients

Question 3. Expansion Appliance.
Answer.

• Appliance for RME
  • Removable – Split acrylic plate
  • Fixed
• Tooth and tissue borne
  • Derichsweiler type
  • Hass type
• Tooth borne
  • Issacson type
  • Hyrax type
• Appliances for Slow Expansion
  • Jack screw
  • Coffin spring
  • Quad helix
  • Fixed appliance

Question 4. Slow Expansion Appliance.
Answer.

• Jack screw:
  • It is incorporated in the appliances
  • Have more spread out activation schedule
  • Have smaller pitch
• Coffin spring:
  • Removable slow expansion appliance by Walter Coffin
  • Wire used – 1.25 mm thick
  • Design – Omega shaped wire – Ove mid-palatal region
  • Free ends of wire – Embedded in acrylic
  • Activation – Pulling two sides apart
  • Use – Dento-alveolar expansion in adults
  • Skeletal expansion in younger patients
• Quad helix:
  • Introduced by Walter coffin
  • Wire used – 0.038 inch
    • Parts
• Bands – Anterior bridge – Connects anterior helices
• Palatal bridge – Connects anterior and posterior helices
• Outer arms – Free ends adjacent to posterior helices
  • Soldered on lingual aspect of molar bands
• Uses: Expansion of narrow arch
  • Rotation of molars

Question 5. Types of Expansion Screws.
Answer.

• 3D screws
• Split midline screw
• Jack screw

Expansion Viva Voce

• Coffin spring and quad helix are used for palatal expansion
• Rapid palatal expansion should be carried out prior to ossification of midpalatal suture
• In rapid expansion two turns daily of 0.5mm is done
• In slow expansion the rate is 0.5 mm per week
• In rapid expansion, the ratio of skeletal to dental expansions is 4:1
• In slow expansion, the ratio of skeletal to dental expansions is 1:1
• In rapid expansion, force generated – 2-4 pounds
• In slow expansion, force generated – 10-20 pounds
• Treatment completed in rapid expansion – 1-2 weeks
• Treatment completed in slow expansion – 2-5 months

Genetics In Orthodontics Short Essays

Question 1. Genetic malocclusions.
Answer.

• Disturbance in tooth size: Micrognathia, macrognathia
• Disturbance in tooth number:
  • Hypodontia
  • Anodontia
  • Oligodontia etc.
• Disturbance in alignment of teeth:
  • Abnormal overjet and overbite
  • Open bite
• Effecting other structures:
  • Cleft lip and palate
    • High arched palate
  • Bimaxillary protrusion
  • Bimaxillary atresia
• Syndromes associated with it:
  • Down’s syndrome
  • Gardner’s syndrome
  • Marfan’s syndrome
  • Cleido-cranial dysplasia
  • Mandibulo facial dysostosis
• General conditions:
  • Cherubism
  • Osteogenesis imperfecta
  • Retarded tooth eruption

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

Question 2. Importance of Genetics in Orthodontics.
Answer.

• First recognized by Frederick G. Kussel in 1836
• He found that some of the malocclusions are transmitted from one generation to other
• The cause of relapse also has a hereditary influence
• Occlusal malrelations, jaw positioning and pressure habits are all results of genetic alteration
• Some of examples of genetic malocclusions are
  • Disturbance in tooth size: Micrognathia, macrognathia
  • Disturbance in tooth number:
    • Hypodontia
    • Anodontia
    • Oligodontia etc.
  • Disturbance in alignment of teeth:
    • Abnormal overjet and overbite
    • Open bite
  • Effecting other structures:
    • Cleft lip and palate
  • High arched palate
    • Bimaxillary protrusion
    • Bimaxillary atresia
  • Syndromes associated with it:
    • Down’s syndrome
    • Gardner’s syndrome
    • Marfan’s syndrome
    • Cleidocranial dysplasia
    • Mandibulo facial dysostosis
  • General conditions:
    • Cherubism
    • Osteogenesis imperfecta
    • Retarded tooth eruption

Question 3. Syndromes and malocclusions.
Answer.

Genetics In Orthodontics Short Questions And Answers

Question 1. Genetic Counselling.
Answer.

It is communication between the counsellor and the patients having hereditary disease which enables the parents to decide to continue pregnancy/to abort

• It is carried out only between counsellor and parents’ confidential
• Decisions must be on the patient, the counsellor must not force the patient
• Counsellor must be confirmed about the diagnosis and severity of the disease
• Counsellor must reveal all the possible sequelae of the hereditary diseases

Question 2. Twin Studies
Answer.

It involves the study of human things

Human twins are of 2 types

Introduction To Orthodontics Definition

Orthodontics:

Orthodontics includes the study of the growth and development of the jaws and face particularly and the body generally as influencing the position of the teeth, the study of action and reaction of internal and external influences on the arrested and perverted development.

Introduction To Orthodontics Important Notes

Jackson’s Triad:

• Functional Efficiency
  • As malocclusion affects normal functioning of stomatognathic system
  • Orthodontic treatment restores it
• Structural balance
  • Three tissues constituents oro-facial region i.e., dentoalveolar, skeletal and soft tissues
  • Orthodontic treatment obtains a balance among them
• Esthetic harmony
  • Malocclusion effects the facial appearance of the individual
  • This effects the psychology of the person
  • Thus orthodontic treatment prevents this by improving the facial appearance

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

Introduction To Orthodontics Short Essays

Question 1. Aims of orthodontics.
Answer.

• Summarized by Jackson
• Also termed as Jackson’s triad

Aims Of Orthodontics:

• Functional Efficiency:
  • As malocclusion affects normal functioning of stomatognathic system
  • Orthodontic treatment restores it
• Structural Balance:
  • Three tissues constituents oro-facial region i.e., dentoalveolar, skeletal and soft tissues
  • Orthodontic treatment obtains a balance among them
• Esthetic harmony:
  • Malocclusion effects the facial appearance of the individual
  • This effects the psychology of the person
  • Thus orthodontic treatment prevents this by improving the facial appearance

Introduction To Orthodontics Short Questions And Answers

Question 1. Define orthodontics.
Answer.

By British Society

Orthodontics includes the study of the growth and development of the jaws and face particularly and the body generally as influencing the position of the teeth, and the study of action and reaction of internal and external influences on the arrested and prevented development.

Question 2. Sequele of Malocclusion.
Answer.

• Poor facial appearance
• Risk of caries
• Predisposition to periodontal diseases
• Psychological disturbances
• Risk of trauma
• Abnormalities of function
• TMJ problems

Question 3. Jackson’s triad/Aims of orthodontics.
Answer.

• Functional efficiency
• Structural balance
• Esthetic harmony

Question 4. Need for orthodontic treatment.
Answer.

• For esthetic problems
• For restoration of functions
• For the balance of oro-facial structure
• To prevent periodontal problems

Question 5. Angle’s contribution to orthodontics.
Answer.

• Father of Modern Orthodontics
• Classification of malocclusion
• Introduction of orthodontics as a separate branch
• Started a school of orthodontics ar St.Louis, New London
• Advocated arch expansion

Introduction To Orthodontics Viva Voce

• Aesthetic harmony is the most common reason for seeking orthodontic care
• Edward Hartely Angle is the father of modern orthodontics
• Pierre Fauchard is the founder of modern dentistry
• Edward H Angle promoted orthodontics as a specialty
• William E Magil was the first to band the teeth for active tooth movement
• Hippocrates is the pioneer of medical science
• Le Felon first coined the word orthodontics

Orthodontic Appliances General Concepts Short Questions

Question 1. Advantages and disadvantages of removable appliances.
Answer.

Removable Appliances Advantages:

• Oral hygiene maintenance
• Useful in tipping movement
• Less chair time
• Convenient to operators to handle more patient
• Fewer forces required
• Not technique sensitive
• Easy to fabricate
• Relatively cheaper
• Damaged appliances can be replaced

Removable Appliances Disadvantages:

• Poor patient cooperation
• Capable of only tipping movement
• Prolonged duration of treatment
• Difficult to treat multiple rotations
• Difficult to close residual space created due to extraction
• Risk of damaging and misplacing appliances by patient
• Cannot be used to treat severe cases of Class 2 and Class 3 malocclusions with unfavorable growth pattern

Question 2. Ideal requisites of Orthodontic appliances.
Answer.

• Biologic requirements:
  • Able to result in desired tooth movement
  • Should not create any damage to oral structures
  • Should not interfere with growth
  • Should not interfere with oral functions
  • Should not create unwanted tooth movement
  • Biocompatible
  • Should not disintegrate
• Mechanical requirement
  • Simple to fabricate
  • Not bulky
  • Strong to withstand forces
  • Able to apply forces to tooth
  • Universal applicable
• Hygienic
  • Should be self-cleansing
• Esthetic
  • Esthetically acceptable

Orthodontic Appliances General Concepts Short Questions And Answers

Question 1. Disadvantages of Fixed Appliances.
Answer.

• Difficult to maintain oral hygiene
• More time consuming
• More chair time required
• Technique sensitive
• May apply misdirected forces
• Frequent visits required
• Expensive

Question 2. Advantages of Fixed Appliances.
Answer.

• Cooperation of the patient is achieved
• Various tooth movements are possible
• Tooth movement of multiple teeth is possible simultaneously
• Good occlusion is achieved
• More precise tooth movements are possible

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

• Can be used in complicated malocclusions
• Better anchorage is obtained
• Management of appliances possible
• Convenient for the operator as no need for timely wear of the appliance
• Less time for treatment required

Question 3. Ideal requirements of removable appliances.
Answer.

• Biologic requirements:
  • Able to result in desired tooth movement
  • Should not create any damage to oral structures
  • Should not interfere with growth
  • Should not interfere with oral functions
  • Should not create unwanted tooth treatment
  • Biocompatible
  • Should not disintegrate
• Mechanical requirement:
  • Simple to fabricate
  • Not bulky
  • Strong to withstand forces
  • Able to apply forces to tooth
  • Universal applicable
• Hygienic:
  • Should be self-cleansing
• Esthetic:
  • Esthetically acceptable

Question 4. Advantages of removable appliances.
Answer.

• Oral hygiene maintenance
• Useful in tipping movement
• Less chair time
• Convenient for the operator to handle movement
• Fewer forces required
• Not technique sensitive
• Easy to fabricate
• Relatively cheaper
• Damaged appliances can be replaced

Orthodontic Diagnosis Important Notes

• Cephalic index
  • The shape of the head can be evaluated based on a cephalic index of the head formulated by Martin and Saller
  • Cephalic index = posterior facial height / anterior facial height

• Facial form

• Types of lips

• Facial divergence

• Nasolabial angle
  • It is an angle formed between the lower border nose and a line connecting the nose and upper lips
  • The normal value is 110 degrees
  • Reduced in patients with proclined maxillary anterior or prognathic maxillary
  • Increased in patients with retrognathic maxilla or reclined maxillary anterior
• Path of closure of mandible
  • Backward in class 2 division 2
  • Forward in pseudo-class 3
  • Lateral in unilateral crossbites

Orthodontic Diagnosis Long Essays

Question 1. Discuss in detail the various diagnostic aids used in orthodontics.
Answer.

Diagnosis:

• It involves the collection of pertinent data in a systemic manner to help identify the nature and cause of the problem

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

Diagnosis Aids:

• Comprehensive orthodontic diagnosis is established by the use of certain clinical implements called diagnostic aids

Types Of Diagnosis Aids:

• Essential Diagnostic aids
  • Case history
  • Clinical examination
  • Study models
  • Certain radiographs
  • Facial radiographs
• Supplemental diagnostic aids
  • Specialized radiographs
  • Electromyographs
  • Hand wrist radiographs
  • Endocrine tests
  • Estimation of basal metabolic rates
  • Diagnostic set-up
  • Occlusograms
• Essential Diagnostic aids:
  • Aids that are important for all cases
  • Involves

Case History involves:

• Personal details:
  • Name – For maintaining a record
    • Addressing patient
    • For communication
  • Age – for treatment planning
    • Growth period – Myofunctional appliances
    • After cessation of growth-surgical treatment
  • Sex – growth spurts differ in both sex
  • Address – for further correspondence

• Chief complaints: Help to identify the expectations of the patient
• Medical history: epilepsy, diabetes, and blood dyscrasias complicate the treatment
• Dental history: to know the attitude of the patient toward treatment
• Pre-natal history: for knowing the condition of the mother during pregnancy
  • Forcep delivery leads to cross-bite
• Post-natal history: to know milestones of development
• Family history: some occlusions like clefts are hereditary

Clinical Examination:

General:

• Height
• Weight
• Gait
• Posture
• Body build

Extra-Oral:

• Head shape
• Facial form
• Facial Profile
• Facial symmetry
• Facial divergence
• Anteroposterior relationship
• Facial proportions
• Lips
• Nose
• Nasolabial angle

Intra-Oral:

• Tongue
• Palate
• Gingiva
• Frenal attachment
• Tonsils
• Adenoids
• Dentition

Functional Examination:

• Postural rest position
• Path of closure
• TMJ
• Swallowing
• Speech
• Respiration

Study models:

• Provide a 3D view of the situation

Uses Of Orthodontics:

• Studies occlusion from all aspects
• Enables accurate measurement
• Treatment planning
• Assess the severity of malocclusion
• Motivate the patient
• For mock surgery
• For transparency records

Steps in Fabrication:

• Impression making – By alginate
• Disinfecting it – By Biocide
• Casting the impression – By model stone
• Basing and trimming the cast
• Finishing and Polishing – By fine-grained sandpaper

Radiographs:

• Commonly used radiographs are

Cephalometric: For skeletal malocclusion

• IOPA – to know the bone condition
• Occlusion radiograph – for arch length

Facial Photographs:

• To compare pre and post-treatment conditions

Supplemental Diagnostic Aids

• Require only in specialized cases
• Includes – electromyography
  • Hand wrist radiograph
  • Endocrine test
  • Estimation of BMR (Basal Metabolic Rate)
  • Diagnostic set up
  • Occlusograms
  • MRI, CT scan

Question 2. What are various diagnostic aids in orthodontics? Write in detail about clinical examination and case history records.
Answer.

Diagnostic Aids:

Essential Diagnostic aids:

• Case history
• Clinical examination
• Study models
• Certain radiographs
• Facial photographs

Supplemental diagnostic aids:

• Specialized radiographs
• Electromyographs
• Hand wrist radiographs
• Endocrine tests
• Estimation of basal metabolic rates
• Diagnostic set-up
• Occlusograms

Case History involves:

• Personal details:
  • Name – For maintaining a record
    • Addressing patient
    • For communication
  • Age – for treatment planning
    • Growth period – Myofunctional appliances
    • After cessation of growth-surgical treatment
  • Sex – growth spurts differ in both sex
  • Address – for further correspondence
• Chief complaints: Help to identify the expectations of the patient
• Medical history: Epilepsy, diabetes, and blood dyscrasias complicate the treatment
• Dental history: To know the attitude of the patient toward treatment
• Pre-natal history: For knowing the condition of the mother during pregnancy
  • Forcep delivery leads to cross-bite
• Post-natal history: To know milestones of development
• Family history: Some occlusions like clefts are hereditary

Clinical Examination:

General:

• Height
  • Provide information on physical growth and maturation of the patient that may influence oro-facial development
• Weight
  • Provide information on the physical growth and maturation of the patient that may influence oro-facial development
• Gait
  • Gait abnormality is associated with neuromuscular problems
• Posture
  • Abnormal posture can predispose to malocclusion
• Body build
  • Types:
    • Aesthetic
      • Thin physique
      • Narrow dental arches
    • Plethoric
      • Obese persons
      • Large, square dental arches
    • Athletic
      • Normal built
      • Normal-size dental arches

Extra-Oral:

• Head shape
  • Types:
    • Mesocephalic
      • The average shape of the head
      • Normal dental arches
    • Dolichocephalic
      • Long and narrow head
      • Narrow dental arches
    • Brachycephalic
      • Broad and short head
      • Broad dental arches

Facial form:

• Types:
  • Mesoprosopic
    • Average face from
  • Euryprosopic
    • Broad and short facial form
  • Leptoprosopic
    • Long and narrow facial form

Facial profile:

• Examined by viewing the patient from the side
• Diagnoses gross deviations in the maxillo-mandibular relationship

Types:

• Straight
• Convex
• Concave

Facial symmetry:

• Determines disproportions of the face in transverse and vertical planes

Facial divergence:

• It is an anterior or posterior inclination of the lower face relative to the forehead

Types Of Facial Divergence:

• Anterior divergence
• Posterior divergence
• Straight or orthognathic
• Anteroposterior relationship
  • This can be assessed by the following
• Seat the patient in an upright position
• Ask to occlude gently
• Place index and middle finger at soft tissue points A and B respectively
• In class 1 hand is at an even level
• In class 2 Index finger is anterior to the middle finger
• In class 3 Middle finger is ahead of the forefinger

Facial proportions:

• The face is divided into three equal thirds by four horizontal planes
• At the level of hairline
• Supraorbital ridge
• The base of the nose
• The inferior border of the chin

Lips:

• Types:
  • Competent lips
  • Incompetent lips
  • Potentially incompetent lips
  • Everted lips

Note:

• It contributes to the esthetics of the face

Nasolabial angle:

• It is the angle formed between the lower border of the nose and the line connecting the intersection of the nose and the upper lip
• It is normally 110 degrees

Intra-Oral:

Tongue:

• Abnormalities in the tongue disturb muscle balance and equilibrium leading to malocclusion

Palate:

• Examined for
  • Palatal depth
  • Presence of swelling
  • Mucosal ulceration
  • Presence of clefts
  • Third rugae

Gingiva:

• Examined for
  • Inflammation
  • Recession
  • Mucogingival lesions

Frenal attachment:

• Abnormal labial frenum leads to midline diastema
• Ankyloglossia leads to the narrowing of the maxillary arch

Tonsils:

• Abnormal inflamed tonsils cause alteration in tongue and jaw posture

Adenoids:

Dentition:

• Assess the following
  • Number of teeth present
  • Number of teeth missing
  • Status of teeth-erupted or unerupted
  • Presence of caries, restorations, or malformed
  • Assess occlusion
  • Assess overjet and overbite
  • Assess individual tooth irregularities like rotations, intrusion, and extrusions
  • Assess transverse relationship
  • Examine the upper and lower arch separately

Question 3. Exumerate essential diagnostic aids. Describe study models in detail.
Answer.

Essential Diagnostic Aids:

• Case history
• Clinical examination
• Study models
• Certain radiographs
• Facial photographs

Study Models:

Uses Of Diagnostic Aids:

• Studies occlusion from all aspects
• Enables accurate measurement
• Treatment planning
• Assess the severity of malocclusion
• Motivate the patient
• For mock surgery
• For transparency records

Requirements Of Diagnostic Aids:

• Should accurately reproduce oral structures
• Should be pleasing to the eye
• Should accurately reproduce occlusion
• Should have a clean, smooth surface
• Should reproduce as much of the alveolar process as possible

Parts Of Diagnostic Aids:

• Anatomic portion
• Artistic portion

Steps:

• Impression making

Disinfecting the impression

• Casting the impression – Using orthodontic stone/model stone
• Basing and trimming of cast

• Trimming
  • Step 1: Trimming of mandibular base
  • Step 2: The back of the mandibular model is made perpendicular to the midline
  • Step 3: Both casts should occlude
  • Step 4: Backs of both casts are made right-angled to base
  • Step 5: Buccal cuts are made on mandibular cast
  • Step 6: Anterior segments made on lower cast
  • Step 7: Posterior cuts on the lower cast
  • Step 8: Buccal cuts made on the upper cast
  • Step 9: Anterior cuts on the upper cast
  • Step 10: Posterior cuts on the upper cast

• Finishing and polishing – Done using fine-grained sandpaper

Orthodontic Diagnosis Short Essays

Question 1. Intra-oral X-rays in Orthodontics
Answer.

Types Of Intra-Oral X-rays:

Intra-Oral Periapical Radiograph:

• Techniques:
  • Paralleling technique
  • Bisecting angle technique
• Uses:
  • View the presence/absence of teeth
  • Supernumerary teeth
  • Root formation
  • Periapical pathology
  • PDL space
  • The contour of alveolar bone – to assess the abnormality
  • Unerupted teeth – for tooth morphology
• Disadvantages:
• Not convenient for the entire dentition
• Gag reflex
• Uncomfortable for children

Bitewing:

• Uses:
  • To assess the height and contour of bone
  • To evaluate periodontal changes
  • To assess interproximal calculus

Occlusal:

• Uses:
  • For impacted/unerupted teeth
  • For supernumerary teeth
  • For foreign bodies
  • To view the effects of the arch expansion procedure

Question 2. Inter-incisal angle.
Answer.

It is the angle formed between the long axis of the upper and lower incisors

• Value – 135.4°
• Range – 130 – 150.5°

Significance Of Inter-incisal Angle:

• Increased in Class 2, Division 2
• Decreased – Class 1 bimaxillary protrusion
  • Class 2 Division 1

Question 3. Occlusal X-ray.
Answer.

Advantages Of Occlusal X-ray:

• Views a large segment of the dental arch
• For viewing palate and floor of mouth
• Useful in trismus

Uses Of Occlusal X-ray:

• Locate impacted teeth
• Locate fracture
• Locate supernumerary teeth
• Locate foreign bodies
• Locate effects of arch expansion procedures
• Assess the arch length
• Assess any pathology of jaws

Question 4. Overjet and Overbite.
Answer.

Overjet: It is the horizontal overlapping of maxillary and mandibular anterior

Value: 1.5 – 2mm

Significance Of Overjet: Increases in open bite cases

• Increases in anterior proclination

Overbite: It is the vertical overlapping of maxillary and mandibular anterior

Value: 1.5 – 2mm

Significance Of Overbit: Decrease – Deep bite

Increase: Open bite

Orthodontic Diagnosis Short Questions And Answers

Question 1. Facial Divergence.
Answer.

It is defined as an anterior/posterior inclination of the lower face relative to the forehead

Types Of Facial Divergence:

• Anterior divergent: A line between the forehead and chin inclines anteriorly
• Posterior divergent: A line between forehead and chin inclines posteriorly
• Straight/Orthognathic: A line between the forehead and chin is straight or perpendicular to the floor.

Question 2. Uses of Panoramic Radiograph./Orthopentogram
Answer.

• Assessing dental development
  • Studying root resorption/root formation
  • For Ankylosis
  • Impacted teeth
  • Path of eruption
  • Diagnose pathology
  • Status of eruption
  • Unerupted teeth

Question 3. Bite Wing Radiographs.
Answer.

Records coronal part of upper and lower dentition together

Uses Of Bite Wing Radiographs:

• For proximal caries
• For interdental bone contour
• For secondary caries
• Detect overhanging restoration
• Detect periodontal changes
• Detect interproximal calculus

Question 4. Electromyography.
Answer.

Used for recording the electrical activity of muscles

Types Of Electrodes Used:

• Surface electrode – Plated superficially
• Needle electrode – Placed deeply

Useful In:

• In severe Class 2 division 1 malocclusion
• Abnormal buccinator activity
• Overclosure of jaws
• Cerebral palsy
• After orthodontic therapy

Question 5. Clinical Evaluation of Facial Profile.
Answer.

The patient is viewed from the side

Reference Lines:

• A line from forehead to point A
• A line from point A to pogonion

Types Of Profiles:

• Straight: Two lines straight line Ex. Class 1 cases
• Convex: Two lines form an angle with concavity facing tissue Ex. Class 2, Division 1
• Concave: Two lines form an angle with convexity facing tissue Ex. Class 3 malocclusion

Question 6. Importance of Family History.
Answer.

• Some malocclusions are hereditary
• These affect the treatment planning
• Thus details of it should not be neglected Ex. Class 2 malocclusion, Cleft lip and palate

Question 7. Kesling’s diagnostic setup.
Answer.

• Proposed by H.D. Kesling
• Used for assessing the effect of treatment

Procedure Of Kesling’s Diagnostic:

Question 8. Freeway Space.
Answer.

• The position of the mandible at which muscles that are useful in opening and closing of jaws are in a state of minimal contraction is called posture rest position
• At this position, space is present between both the jaws
• This is called free-way space

Value – 3mm

Site – In canine region

Question 9. Gnathostatic Models.
Answer.

• Type of study model
• Uses: Provide 3D view of occlusion
• For treatment planning
• For assessing the outcome

Gnathostatic:

Question 10. Overjet.
Answer.

• It is a horizontal overlapping of the maxillary and mandibular anterior
• Value: 1.5 – 2mm
• Significance Of Overjet: Increases in open bite cases
  • Increases in anterior proclination

Question 11. Nasolabial angle.
Answer.

• It is the angle formed between the lower border of the nose and the line connecting the intersection of the nose and the upper lip
• It is normally 110 degrees
• Reduces in
  • Patients having proclined upper anterior or prognathic maxilla
• Increases in
  • Patients with retrognathic maxilla or reclined maxillary anterior

Question 12. Cephalic index
Answer.

• The cephalic index was described by Martin and Saller in 1957
  • It is calculated as follows
• Cephalic index = Maxillary skull width / Maxillary skull length

Interpretation Of Cephalic Index:

• Value – 76-80.9
  • Indicates mesocephalic individuals
• Value – 81-85.4
  • Indicates brachycephalic individuals
• Value < 75.9
  • Indicates dolichocephalic individuals
• Value > 85.5
  • Indicates hyperbradycephalic

Question 13. Orthodontic study models
Answer.

Uses Of Orthodontic Study Models:

• Studies occlusion from all aspects
• Enables accurate measurement
• Treatment planning
• Assess the severity of malocclusion
• Motivate the patient
• For mock surgery
• For transparency records

Requirements Of Orthodontic Study Models:

• Should accurately reproduce oral structures
• Should be pleasing to the eye
• Should accurately reproduce occlusion
• Should have a clean, smooth surface
• Should reproduce as much of the alveolar process as possible

Parts Of Orthodontic study models:

• Anatomic portion
• Artistic portion

Question 14. Importance of medical history
Answer.

• Some medical conditions contraindicate the use of orthodontic appliances
• They may require special precautionary measures to be taken before or during orthodontic therapy
• It is advisable to delay orthodontic treatment in patients suffering from epilepsy until it is controlled
• Patients with a history of blood dyscrasias may need special management if extractions are planned
• Diabetic patients can undergo orthodontic therapy if it is under control
• Patients having rheumatic fever or cardiac anomalies require antibiotic coverage for certain dental procedures
• Children who are severely handicapped either mentally or physically may require special management
• The use of aspirin may impede orthodontic tooth movement
• Patients suffering from acute, debilitating conditions should be allowed to recover before initiating orthodontic treatment

Orthodontic Diagnosis Viva Voce

• Hyperactive mental activity and abnormal buccinators activity are seen in class 2 division 1
• Overclosure of jaws is associated with accentuated temporalis muscle activity
• Normally the upper lip covers the anterior labial surface of the upper anterior except for the incisal 2-3mm while the lower lip covers the entire labial surface of the lower anterior and 2–3mm of the incisal edge of the upper anterior