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Anchorage Important Notes

• Advantages of Extraoral anchorage
  • Greater forces can be applied
  • Permits movement of teeth in one arch without movement of teeth in another arch
• Sites for extra oral anchorage
  • Occipital region
  • Cervical region
  • Parietal region
  • Face
• Reinforced anchorage
  • More than one type of resistance unit is utilized
  • Ex: orthopaedic appliances, anterior inclined plane, transpalatal arch
• Reciprocal anchorage
  • Resistance is offered by two units with equal and opposite forced
  • Example closure of midline diastema, split expansion appliance and correction of crossbite
• Types of anchorage with examples

Anchorage Long Essays

Question 1. Define and classify anchorage. Explain in detail about intra-oral anchorage and factors effecting anchorage.
Answer.

Anchorage:

Definition – By Graber:

It is the nature and degree of resistance to displacement offered by an anatomic unit for the purpose of effecting tooth movement

Classification – By Moyer:

According to force application:

• Simple anchorage
• Stationary anchorage
• Reciprocal anchorage

According to jaws involved:

• Intramaxillary
• Intermaxillary

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

According to site of anchorage:

• Intraoral
• Extraoral
• Muscular

According to no.of anchorage units:

• Simple
• Compound
• Multiple

Intraoral Anchorage: Anchorage in which all the resistance units are situated within the oral cavity.

Both teeth to be moved, and the teeth acting as anchorage, are situated in oral cavity

Sources Of Anchorage

• Teeth:
  • Remaining teeth, other that the teeth to be moved act as anchorage units
  • It depends on its
    • Root form
    • Root length
    • Root no and size
    • Ankylosis
    • Tooth inclination
• Alveolar bone:
  • On application of extreme forces bone permits tooth movement
• Basal bone:
  • i.e. hard palate and lingual surface of mandible
  • Used to augment intramaxillary or intermaxillary anchorage
• Musculature:
  • Use of hypertonic labial musculature through lip bumper

Factors Effecting Anchorage

• No of teeth being moved
  • Greater the number
  • Greater need of anchorage
• Type of teeth being moved
  • Slender anterior teeth – less anchorage
  • Multirooted teeth – more anchorage needed
• Type of tooth movement
  • Tipping movement – less anchorage
  • Bodily movement – more anchorage

• Duration of tooth movement
  • Prolonged duration – undue strain
• Skeletal pattern:
  • Vertical grower – More anchorage loss
  • Horizontal grower – Less anchorage loss
• Occlusal interlock
  • Good buccal occlusion – Resist tooth movement.

Question 2. Define Anchorage. Discuss different types of anchorage with illustrations.
Answer.

Definition – By Moyer:

It is the nature and degree of resistance to displacement offered by anatomic unit to effect tooth movement

Classification – By Moyer:

According to force application:

• Simple anchorage
• Stationary anchorage
• Reciprocal anchorage

According to jaws involved:

• Intramaxillary
• Intermaxillary

According to site of anchorage:

• Intraoral
• Extraoral
• Muscular

According to no.of anchorage units:

• Simple
• Compound
• Multiple

Simple anchorage:

• It is dental anchorage in which manner and application of force is such that it tends to change the axial inclination of tooth/teeth that form the anchorage unit in the plane of space in which the force is being applied.

Manner:

• Removable appliance used to move the teeth
• Here the combined root surface area of anchorage units must be double that of teeth to be moved

Stationary anchorage:

• It is defined as dental anchorage in which the manner and application of force tends to displace the anchorage unit bodily in the plane of space in which the force is being applied.
• Resistance to bodily movement is greater than that of tipping movement

Reciprocal anchorage:

• It is resistance offered by two malposed units when the dissipation of equal and opposite forces tends to move each unit towards more normal occlusion
• Example Closure of mid line diastema, cross bite elastics, arch expansion

Intraoral anchorage:

• Anchorage in which all the resistance units are situated within the oral cavity
• Both teeth to be moved, and the teeth acting as anchorage, are situated in oral cavity

Sources Of Intraoral Anchorage:

Teeth:

• Remaining teeth, other that the teeth to be moved act as anchorage units

Alveolar bone:

• On application of extreme forces bone permits tooth movement by its resorption

Basal bone:

• i.e. hard palate and lingual surface of mandible
• Used to augment intramaxillary or intermaxillary anchorage

Musculature:

• Use of hypertonic labial musculature through lip bumper

Extraoral anchorage:

• Resistance units are located outside oral cavity
• Example Occiput, back of neck, cranium and face
• Head gear, face mask

Muscular anchorage:

• Perioral musculature acts as resistance units

Example Use of lip bumper

Intramaxillary anchorage: Teeth to be moved and the resistance units, both are situated in same jaw

Intermaxillary anchorage [Baker’s anchorage]: Anchorage units are located in one jaw while teeth to be moved are located in other jaw Ex. Class 2 elastic traction between lower molars and upper anteriors

Simple/Primary Anchorage: Single tooth with greater alveolar support it used to move tooth with lesser alveolar support.

Compound Anchorage: More than one teeth with greater alveolar support is used to move tooth with lesser alveolar support.

Reinforced/Multiple Anchorage: Anchorage in which more than one type of resistance unit is termed reinforced anchorage. Ex: Extraoral anchorage, upper anterior inclined plance, transpalatal arch.

Question 3. Define anchorage. Classify it and discuss in detail the methods to reinforce anchorage.
Answer.

Definition – By Graber:

• It is the nature and degree of resistance to displacement offered by an anatomic unit for the purpose of effecting tooth movement

Classification – By Moyer:

According to force application:

• Simple anchorage
• Stationary anchorage
• Reciprocal anchorage

According to jaws involved:

• Intramaxillary
• Intermaxillary

According to site of anchorage:

• Intraoral
• Extraoral
• Muscular

According to no.of anchorage units:

• Simple
• Compound
• Multiple

Methods of Reinforcing Anchorage:

Extraoral forces:

• Forces generated from Cranium, back of neck and face are used

Upper Anterior Inclined Plane:

Effects: Forward gliding of mandible during jaw closure

• Stretching of retractor muscles
• Application of distal force on maxillary teeth

Modification Saved appliances with additional upper incisal capping

Use of Transpalatal Arch and Lingual Arches:

• Transpalatal Arch: Fixed mechano therapy
  • Transverse palate connecting 1st permanent molars of either side
• Lingual Arch:
  • Connects contra lateral lower molars through lingual aspects
  • Prevents medial movement of lower molar

Anchorage Short Essays

Question 1. Extra Oral Anchorage.
Answer.

Extraoral anchorage:

• Resistance units are located outside oral cavity
• Example Occiput, back of neck, cranium and face
• Head gear, face mask

Question 2. Baker’s Anchorage/Inter-maxillary anchorage.
Answer.

Baker’s Anchorage

Anchorage units are located in one jaw while teeth to be moved are located in other jaw Ex. Class 2 elastic traction between lower molars and upper anteriors

Examples Of Baker’s Anchorage:

• Baker’s anchorage is a form of intermaxillary anchorage used to adjust the jaw relationship and teeth by using elastics from maxilla and mandible
• Class 2 elastics worn from mandibular molars to maxillary anteriors used to retract the maxillary anteriors
• Class 3 elastics worn from maxillary molars to mandibular anteriors used to retract the mandibular anteriors

Question 3. Reinforced Anchorage.
Answer.

Reinforced Anchorage

• Anchorage in which more than one type of resistance unit termed reinforced anchorage.
• Resistance units become more effective when more units are added because the reactionary force is distributed over a larger area
• Distribution of force over large area means keeping force light which minimizes trauma and pain during treatment

Examples:

Extraoral forces:

• Forces generated from Cranium, back of neck and face are used

Upper Anterior Inclined plane:

Effects: Forward gliding of mandible during jaw closure

• Stretching of retractor muscles
• Application of distal force on maxillary teeth

Modification saved appliances with additional upper incisal capping

Use of Transpalatal Arch and Lingual Arches:

• Transpalatal Arch: Fixed mechano therapy:
  • Transverse palate connecting 1st permanent molars of either side
• Lingual Arch:
  • Connects contra lateral lower molars through lingual aspects
  • Prevents medial movement of lower molar

Question 4. Anchorage.
Answer.

Definition – By Graber:

• It is the nature and degree of resistance to displacement offered by an anatomic unit to effect tooth movement

Classification – By Moyer:

According to force application:

• Simple anchorage
• Stationary anchorage
• Reciprocal anchorage

According to jaws involved:

• Intramaxillary
• Intermaxillary

According to the site of anchorage:

• Intraoral
• Extraoral
• Muscular

According to no.of anchorage units:

• Simple
• Compound
• Multiple

Reciprocal Anchorage:

• It is the resistance offered by two malposed units when the dissipation of equal and opposite forces tends to move each unit toward more normal occlusion
• Example Closure of mid-line diastema, crossbite elastics, arch expansion

Question 5. Methods of Reinforcing Anchorage.
Answer.

Extraoral forces:

• Forces generated from the Cranium, back of the neck and face are used

Upper Anterior Inclined Plane:

Effects: Forward gliding of mandible during jaw closure

• Stretching of retractor muscles
• Application of distal force on maxillary teeth

Modification Saved appliances with additional upper incisal capping

Use of Transpalatal Arch and Lingual Arches:

• Transpalatal Arch: Fixed mechanic therapy:
  • Transverse palate connecting 1st permanent molars of either side
• Lingual Arch:
  • Connects contra lateral lower molars through lingual aspects
  • Prevents medial movement of lower molar

Anchorage Short Questions And Answers

Question 1. Reciprocal Anchorage.
Answer.

Reciprocal Anchorage

It is the resistance offered by two malposed units when the dissipation of equal and opposite forces tends to move each unit toward more normal occlusion

Example Closure of mid-line diastema, crossbite elastics, arch expansion

Question 2. Simple Anchorage.
Answer.

Simple Anchorage

It is a dental anchorage in which the manner and application of force is such that it tends to change the axial inclination of tooth/teeth that form the anchorage unit in the plane of space in which the force is being applied.

Manner: Removable appliance used to move the teeth. Here the combined root surface area of anchorage units must be double that of teeth to be moved

Question 3. Factors affecting anchorage.
Answer.

Factors affecting anchorage

• Biological factors:
  • Teeth
  • Size of anchoring unit
  • Axial inclination of teeth
  • Use of optimum force
  • Differential force system
  • Persistent habits
• Mechanical factors:
  • Friction
  • Type of tooth movement
  • Technique employed

Question 4. Anchorage loss.
Answer.

Anchorage loss

• The undersirable movement of the anchor teeth in excess of that planned treatment is known as anchorage loss
• Reasons for anchorage loss
  • Excessive force
  • Improper treatment planning
  • Resistance between arch wires and brackets
• Methods to prevent anchorage loss are
  • Use of anchorage savers like transpalatal arches, lingual arches
  • Use of optimum and differential force
  • Utilizing muscular forces
  • Reinforcement of anchorage.

Question 5. Baker’s anchorage
Answer.

Baker’s anchorage

• Anchorage units are located in one jaw while teeth to be moved are located in other jaw Example Class 2 elastic traction between lower molars and upper anteriors

Examples Of Baker’s Anchorage:

• Baker’s anchorage is a form of intermaxillary anchorage used to adjust the jaw relationship and teeth by using elastics from maxilla to mandible
• Class 2 elastics worn from mandibular molars to maxillary anteriors used to retract the maxillary anteriors
• Class 3 elastics worn from maxillary molars to mandibular anteriors used to retract the mandibular anteriors

Anchorage Viva Voce

• Correction of single tooth cross bite is an example of reciprocal anchorage
• Lip bumper is example of muscular anchorage
• Unwanted movement of anchor teeth is called anchor loss
• Anchorage during orthodontic treatment is mainly obtained from intraoral and Extraoral sources
• Ankylosed teeth serve as excellent anchorage
• In maximum anchorage cases 1/4th extraction space can be lost by movement of anchor units

Types Of Tooth Movement Important Notes

• Couple
  • It is a pair of parallel forces having equal magnitude acting in opposite direction
  • Brings about pure rotation
• Center of resistance

• Center of rotation in different movement

• Types of tipping

• Types of forces

Types Of Tooth Movement Long Essays

Question 1. Define optimum force. Classify and discuss Orthodontic forces.
Answer.

Optimum Orthodontic Force

• It is a force that rapidly moves teeth in the desired position with minimum damage to adjacent tissues and with less discomfort to the patients
• Value – According to Oppenheim and Schwarz, it is equal to capillary pressure i.e. 20-26gm/cm2

Orthopaedic Force.

• It is defined as an act upon a body that changes/tends to change the state of rest or uniform motion of that body
• It has definite magnitude, specific direction, and point of application.

Value – In grams

Generated by – Orthodontic appliances

Significance – Orthodontic treatment depends on it

Types Of Optimum Forces:

Continuous Force:

• Active force
• Decreases little in magnitude between appointment periods
• Example Light wire appliance
• Requirement:
  • Components must be highly flexible
  • Activation must be of low force level
• Results:
  • Direct resorption of root socket
  • No occlusion of blood vessels
  • No sacrifice of nutritional supply
  • No rest period
  • Soft tissue tolerance

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

Intermittent Force:

• Active force
• Declines to zero magnitudes before next appointment
• Example Removable active plates
• Requirements:
  • High stiffness of components
  • Initial activation – twice the expected
• Results:
  • Greater force on teeth
  • Undermining resorption
  • Repair of necrosed soft tissue
  • Resumption of blood supply

Interrupted Force:

• Inactive between appointment intervals
• Has cyclic, long-term magnitude time pattern

• Ex. Extra oral appliance
• Requirements:
  • Should exert heavy forces
  • No decay
  • Have specific magnitude – time pattern
  • Have sufficient inactive period

Types Of Tooth Movement Short Essays

Question 1. Tooth Movement.
Answer.

It is a unique process in which a tooth is made to move through bone.

Types Of Tooth Movement:

Tipping:

• It is a type of tooth movement where a single force is applied to the crown resulting in the movement of the crown in the direction of force and the root in the opposite direction.
• Controlled Tipping:
  • Tooth tips about the center of rotation at its apex.
• Uncontrolled Tipping:
  • The Centre of rotation occurs apical to & very close to the center of resistance.

Types Of Tooth Movement Short Questions And Answers

Question 1. Force and Couple.
Answer.

Force: It is defined as an act upon a body that changes/tends to change the state of rest or uniform motion of that body

• Expressed in grams

Couple: It is a pair of concentrated forces having equal magnitude and opposite direction with parallel but non-collinear lines of action

• Example. Pure rotation

Question 2. Intrusion.
Answer.

• Intrusion is defined as the axial movement of the tooth along the long axis toward the apex of the root
• This tooth movement requires minimum force and the center of rotation passes through the center of resistance
• 10-20g of force is required the periodontal ligament at the apex is compressed over a small area and no area of tension exists

Question 3. Tipping movement.
Answer.

It is a type of tooth movement where a single force is applied to the crown resulting in the movement of the crown in the direction of force and root in the opposite direction.

• Controlled Tipping
  • Tooth tips about the center of rotation at its apex.
• Uncontrolled Tipping
  • The Centre of rotation occurs apical to & very close to the center of resistance.

Question 4. Moment of force.
Answer.

Definition Of Moment of force

• It is defined as the measure of rotational potential of a force concerning a specific axis
• It is a tendency for a force to produce rotation

Calculated by

• Moment = Magnitude of force x distance
• Unit
• Gram millimeters
• Factors determining it
• Magnitude of force
• Distance from the center of resistance

Types Of Tooth Movement Viva Voce

• The center of rotation is the variable point
• The center of resistance is a fixed point
• Tipping is tooth movement around the mesiodistal axis
• Torqueing is tooth movement around fac-io-lingual axis
• Rotation is tooth movement around the long axis of the tooth
• Couple brings about pure rotation
• The unit of measurement of moment of force is gram millimeters
• The center of rotation during intrusion and extrusion is outside the tooth
• The center of resistance in the multi rooted tooth is located at 1-2mm apical to furcation

Biology Of Tooth Movement Important Notes

• Hyalinization – characteristics
  • Tissue degeneration
  • Acellular, avascular area
  • Deposition of clear eosinophilic homogenous substance in periodontal ligament
• Optimum orthodontic forces

• Phases of tooth movement

• Torqueing/reverse tipping
  • During it there is movement of root only without movement of crown
  • Used to correct effects of uncontrolled tipping
• Frontal resorption
  • Occurs on application of light forces
  • Amount of force applied is close to capillary pressure
• Rearward resorption
  • Occurs on application of heavy forces
  • Forms hyalinised zones
• Changes on application of forces
  • Stretching of PDL fibres on tension side
  • Raised vascularity
  • Mobilization of fibroblasts and osteoblasts
  • Formation of osteoid
  • Formation of woven bone

Biology Of Tooth Movement Long Essays

Question 1. Define optimum orthodontic force. Discuss various theories of tooth movement.
Answer.

Optimum Orthodontic Force:

• It is a force which rapidly moves teeth in desired position with minimum damage to adjacent tissues and with less discomfort to the patients
• Value: According to Oppenheim and Schwarz, it is equal to capillary pressure i.e. 20-26gm/cm2

Theories Of Tooth Movement

Pressure – Tension theory – By Schwarz:

• On application of force to tooth, 2 areas are formed
• Pressure area – in direction of force
• Tension area – in opposite direction
  • Results in:
    • Bone resorption in pressure area
      • Bone deposition in tension area

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

Fluid-Dynamic Theory – By Bien:

Proposed by: Bien

Theory: Tooth movement occurs as a result of alterations in fluid dynamics in the periodontal ligament

• Has limited passage of fluids
• Removal of force of short duration causes replenishment of this fluid
• While forces of greater magnitude leads to squeezing out of fluid
• Results in decreased tooth movement called squeeze film effects

Changes Of Optimum Orthodontic Forces:

Bone Bending and Piezoelectric Theory – By Farrar:

• Piezoelectricity is a phenomenon observed in many crystalline materials in which a deformation of the crystal structure produces a flow of electric current as a result of the displacement of electrons from one part of the crystal lattice to another
• Sources of Electric Current:
  • Collagen
  • Hydroxyapatite
  • Collagen-hydroxyapatite interface
  • Mucopolysaccharide

Piezoelectric

Bone Bending:

Question 2. Discuss histological changes during orthodontic tooth movement.
Answer.

Orthodontic forces leads to the formation of areas of pressure in the direction of force and areas of tension in the opposite direction around the tooth

Changes Due To Mild Forces:

• On the pressure side:
  • Compression of PDL
  • Increase in blood supply
  • Increase in fibroblasts and osteoblasts
  • Parallel arrangement of bony trabeculae
  • Resorption of the alveolar plate adjacent to the ligament called frontal resorption
• On the Tension side:
  • Stretching of the periodontal membrane
  • Widening of PDL space
  • Increased vascularity
  • Presence of fibroblast and osteoblast
  • Formation of osteoid

• Secondary remodeling changes:
  • Bony changes occurs else where to maintain thickness of alveolar bone
  • Called secondary remodeling
    • Ex. For labial movement of tooth deposition occurs on labial cortical plate and resorption over lingual cortical plate

Changes Due To Extreme Forces:

• Pressure side:
  • Crushing of PDL
  • Approximation of root to lamina dura
  • Occlusion of blood vessels
  • Deprived blood supply
  • Regressive changes occur called hyalinization
  • Bone resorption in marrow spaces below behind and above hyalinized zones
  • Called undermining resorption
• Tension side:
  • Over stretching of PDL
  • Tearing of blood vessels
  • Ischaemia
    • Effects:
      • Increased osteoclastic activity
      • Loosening of tooth
      • Pain and hyperemia of gingiva

Biology Of Tooth Movement Short Essays

Question 1. Undermining Resorption.
Answer.

Undermining Resorption

• Occurs on application of extreme, orthodontic forces
• Occurs on pressure side i.e. in direction of force application around tooth

Changes Of Undermining Resorption:

• Crushing of periodontal ligament
• Approximation of root to lamina dura
• Occlusion of blood vessels
• Deprived of blood supply
• Hyalinized zones formation
• Resorption occurs below, behind and above hyalinized zones
• This is called undermining resorption
  Synonym: Rear ward resorption

Question 2. Hyalinization.
Answer.

Hyalinization

• It is tissue degeneration characterized by formation of a clear, eosinophilic homogenous substance

Location Of Hyalinization:

• Kidneys, lungs etc.
• Irreversible
• But in PDL – Reversible, Bony spicules

Effects Of Hyalinization:

• Shrinkage of PDL fibres
• Pyknotic nuclei formation
• Union of collagenous fibres
• Breakdown of blood vesses walls
• Osteoclasts in marrow spaces
• Non-functioning of ligament
• Absence of resorption

Elimination By:

• By resorption of alveolar bone
• Invasion of cells and blood vessels from periphery

Importance Of Hyalinization:

• Greater forces – Wider hyalinized area
  • Functionless large area of ligament
  • Large area of rearward resorption
• Tipping movement – hyalinized zone close to alveolar creast
• Bodily movement – Close to middle portion of root

Question 3. Tissue changes in Tipping movement.
Answer.

Mild Forces:

Secondary remodeling changes occurs:

• Osteoclatic activity on pressure side
• Osteoblastic activity on tension side

For labial tipping:

• Deposition on outer side of labial alveolar bony plate
• Resportion on lingual side of lingual alveolar bone
  Significance: Maintain uniform thickness of bone

Hyalinization: Hyalinized zones are seen close to alveolar crest

Extreme Forces:

• It results in formation of hyanilized zones at 2 regions
  • At apical area
  • At marginal area

Question 4. Optimum Orthodontic Force.
Answer.

Optimum Orthodontic Force

• It is a force which rapidly moves teeth is desired position with minimum damage to adjacent tissues and with less discomfort to the patients
  Value: According to Oppenheim and Schwarz, it is equal to capillary pressure i.e. 20-26gm/cm2

Properties Of Optimum Orthodontic Force:

• Rapid tooth movement – Clinically
• Less patient discomfort – Clinically Minimum lag phase – Clinically
• Absence of tooth mobility – Clinically
• Maintenence of tooth vitality – Tissue level
• Maximum cellular response – Tissue level
• Frontal resorption – Tissue level

Question 5. Frontal Resorption.
Answer.

Frontal Resorption

• Occurs on application of mild forces to bring about tooth movements
• Occurs on pressure side

Changes Of Frontal Resorption:

• Compression of PDL
• Increased vascularity
• Increased blood supply
• Presence of fibroblast and osteoclast
• Orientation of bony trabeculae parallel to the direction of force application
• Osteoclasts starts resorption adjacent to ligament
• This type of resorption is called frontal resorption

Question 6. Piezo-electric theory.
Answer.

By Farrar:

• Piezoelectricity is a phenomenon observed in many crystalline materials in which a deformation of the crystal structure produces a flow of electric current as a result of displacement of electrons from one part of crystal lattice to other

Sources of Electric Current:

• Collagen
• Hydroxyapatite
• Collagen-hydroxyapatite interface
• Mucopolysaccharide

Piezoelectric:

Question 7. Frontal v/s rearward resorption
Answer.

Frontal v/s rearward resorption

Question 8. Risk of orthodontic treatment.
Answer.

Risk of orthodontic treatment

• Toothache, occasional discomfort
  • When beginning of orthodontic treatment and during each inspection, unpleasant pressure over teeth is present
• Scratches and bruises
  • Bruises may occur on mucosa generally caused by fixed appliances
• White spots on the surface of teeth
  • Occurs due to long term bad oral hygiene
  • White patches appears around the brackets
• Gingivitis
  • Insufficient oral hygiene may lead to gingivitis
• Root shortening
  • Orthodontic appliances exerts force onto roots of the teeth
  • The compressive force is always generated over root surface
  • This reduces the blood supply
  • Results in some of the root surface dissolving away temporarily leading to shortening of root
• Relapse of orthodontic treatment
  • Every orthodontic treatment has a tendency to relapse
  • This can be prevented by use of retainers
• Tooth decay
  • Due to fixed appliances tooth cleaning becomes difficult
  • Due to this number of bacteria increases leading to tooth decay
  • This can be prevented by
    • Avoiding sugary foods and drinks in between meals
    • Maintaining oral hygiene
    • Use of fluoridated toothpaste
    • Use a daily mouthwash containing fluoride

Biology Of Tooth Movement Short Questions And Answers

Question 1. Pressure Tension theory
Answer.

By Schwarz:

• On application of force to tooth, 2 areas are formed
• Pressure area – in direction of force
• Tension area – in opposite direction

Results in:

• Bone resorption in pressure area
• Bone deposition in tension area

Question 2. Biochemical Reactions of Orthodontic force.
Answer.

Biochemical Reactions of Orthodontic force

Question 3. Tissue changes on pressure side.
Answer.

• Changes due to mild forces
  • Compression of PDL
  • Increase in blood supply
  • Increase in fibroblasts and osteoblasts
  • Parallel arrangement of bony trabeculae
  • Resorption of alveolar plate adjacent to ligament called frontal resorption
• Changes due to extreme forces:
  • Crushing of PDL
  • Approximation of root to lamina dura
  • Occlusion of blood vessels
  • Deprived blood supply
  • Regressive changes occur called hyalinization
  • Bone resorption in marrow spaces below behind and above hyalinized zones
  • Called undermining resorption

Question 4. Tissue changes in tipping movement.
Answer.

Mild Forces:

• Secondary remodeling changes occurs:
  • Osteoclatic activity on pressure side
  • Osteoblastic activity on tension side
    • For labial tipping:
      • Deposition on outerside of labial alveolar bony plate
      • Resorption on lingual side of lingual alveolar bone
        Significane: Maintain uniform thickness of bone

Hyalinization: Hyalinized zones are seen close to alveolar crest

Question 5. Optimum orthodontic force.
Answer.

Optimum orthodontic force

• It is a force which rapidly moves teeth in desired position with minimum damage to adjacent tissues and with less discomfort to the patients
• Value: According to Oppenheim and Schwarz, it is equal to capillary pressure i.e. 20-26gm/cm2

Question 6. Hyalinization.
Answer.

Hyalinization

It is tissue degeneration characterized by formation of a clear, eosinophilic homogenous substance

Location Of Hyalinization:

• Kidneys, lungs etc.
• Irreversible
• But in PDL – Reversible, Bony spicules

Effects Of Hyalinization:

• Shrinkage of PDL fibres
• Pyknotic nuclei formation
• Union of collagenous fibres
• Breakdown of blood vessel walls
• Osteoclasts in marrow spaces
• Non-functioning of ligament
• Absence of resorption

Biology Of Tooth Movement Viva Voce

• Application of light forces will result in frontal resorption
• Application of extreme forces will result in undermining or rearward resorption
• Tipping is most common and most simplest type of movement
• Intrusion and translation are difficult to achieve
• Extrusion is easiest of all movements

Model Analysis Important Notes

• Carey’s analysis

• Bolton’s analysis
  • According to Bolton, tooth size is an important factor to be taken into consideration for diagnosis and there exists a ratio between mesio-distal widths of maxillary and mandibular teeth
  • Bolton’s overall ration is 91.3%
  • If overall ratio is less than 91.3%, it indicates maxillary tooth material excess
  • Bolton’s anterior tooth ratio is 77.2%
  • If anterior ratio is less than 77.2%, it indicates maxillary anterior excess
• Tanaka Johnson analysis
  • This analysis does not require any radiographs or reference tables
  • The width of unerupted canines and premolars can be predicted based on width of mandibular incisors
  • Width of maxillary canine and premolars = 11 + 1/2 width of madibular incisors
  • Width of mandibular canine and premolars = 10.2 + 1/2 width of mandibular incisors
• Various model analysis

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

• Requirements of various analysis

Model Analysis Long Essays

Question 1. Classify diagnostic aids. Write briefly about Model analysis.
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
  • Endocrines tests
  • Estimation of basal metabolic rates
  • Diagnostic set-up
  • Occlusograms

Model Analysis:

Involves study of maxillary and mandibular dental arches in all the three planes of space

• Useful in treatment planning
• Useful in maintaining records

Different Analysis:

Carey’s analysis:

• Determination of arch length – From anterior of first permanent molar to mesial surface of opposite first permanent molar
• Determination of tooth material – Mesio-distal width of teeth from 2nd premolar to 2nd premolar
• Determination of the discrepancy – Difference between arch length and tooth material
  • Interference:
    • 0-2.5 mm – Proximal stripping
    • 2.5-5 mm – Extraction of 1st premolars
    • > 5mm – Extraction of 1st premolars

Ashley Howe’s analysis:

• Determination of total tooth material [TTM] – Mesio-distal width of teeth from 1st molar to 1st molars
• Determination of premolar diameter [PMD] – arch width from tip of buccal cusp of 1st premolar to that of opposite side
• Determination of premolar basal arch width [PMBAW] – width from canine fossa of one side to other
  • Interference:
    • PMBAW% – \(\frac{\text { PMBAW } \times 100}{\text { TTM }}\)
    • 37 or less – Need for extraction
    • 44 or more – Non-extraction
    • 37 to 44 – Borderline cases

Ponts analysis:

• By 1909
  • Determination of sum of incisors [SI] – Total mesio-distal width of 4 maxillary incisors
  • Determination of measured premolar value [MPV] – From distal pit of upper first premolar to that of opposite side
  • Determination of measured molar value [MMV] – From mesial pit of one upper first molar to that of opposite sid

• • Determination of calculated premolar value \((\mathrm{CPV})-\mathrm{CPV}=\frac{\mathrm{SI} \times 100}{80}\)
  • Determination of calculated molar value [CMV] – CMV = \(\frac{\text { SI } \times 100}{80}\)
    • Interference:
      • Measured value < Calculated value
      • Need for expansion

Bolton’s analysis:

• Sum of maxillary 12 – Total mesiodistal width of one 1st molar to that of other
• Sum of mandibular 6 – Total mesiodistal width of 6 anteriors
• Sum of maxillary 6 – Total mesiodistal width of 6 anteriors
  • Determines of overall ratio – Overall ratio = \(\frac{\text { Sum of mandibular } 12}{\text { Sum of maxillary } 12} \times 100\)
  • According to Bolton, it should be 91.3%
  • If less than 91.3% – Maxillary tooth material excess
• Determination of Anterior Ratio:
  • Anterior ratio = \(\frac{\text { Sum of mandibular } 6}{\text { Sum of maxillary } 6} \times 100\)
  • According to Bolton, it should be 77.2%
  • If less than 77.2% – Maxillary anterior excess
  • If more than 77.2% – Mandibular anterior excess

Model Analysis Short Essays

Question 1. Arch perimeter analysis.
Answer.

• Carey’s analysis used for maxillary arch is called arch perimeter analysis

Methods Of Arch Perimeter Analysis:

• Determination of arch length – From anterior of first permanent molar to mesial surface of opposite first permanent molar
• Determination of tooth material – Mesio-distal width of teeth from 2nd premolar to 2nd premolar
• Determination of the discrepancy – Difference between arch length and tooth material
  • Interference:
    • 0-2.5mm – Proximal stripping
    • 2.5-5mm – Extraction of 2nd premolars
    • > 5mm – Extraction of 1st premolars

Question 2. Mixed Dentition Analysis.
Answer.

Moyer’s Mixed Dentition Analysis: To evaluate the amount of space available in the arch for erupting permanent canine and premolar

Procedure Of Mixed Dentition Analysis:

Inference Of Mixed Dentition Analysis:

• Compare tooth sizes 3,4 and 5 and the arch length available
• Predicted value > arch length available → Crowding

Radiographic method:

• Determine the width of unerupted teeth
• Erupted teeth in a radiograph and on a cast

i.e. Width of the unerupted tooth to be determined

Question 3. Bolton’s analysis:
Answer.

Methods Bolton’s Analysis:

• The sum of mandibular 12 – Total mesiodistal width of one 1st molar to that of other
• A sum of maxillary 12 – Total mesiodistal width of one 1st molar to that of other
• Sum of mandibular 6 – Total mesiodistal width of 6 anteriors
• A sum of maxillary 6 – Total mesiodistal width of 6 interiors
  • Determination of overall ratio – Overall ratio = \(\frac{\text { Sum of mandibular } 12}{\text { Sum of maxillary } 12} \times 100\)
  • According to Bolton, it should be 77.2%
  • If less than 91.3% of maxillary tooth material excess
• Determination of Anterior Ratio:
  • Anterior ratio = \(\frac{\text { Sum of mandibular } 6}{\text { Sum of maxillary } 6} \times 100\)
  • According to Bolton, it should be 77.2%
  • If less than 77.2% – Maxillary anterior excess
  • If more than 77.2% of mandibular anterior excess

Model Analysis Short Questions And Answers

Question 1. Assessment of tooth mass discrepancy.
Answer.

• Measure the arch length
• Measure the mesiodistal width of teeth

Discrepancy Of Tooth Mass Discrepancy:

• Difference between arch length measures and tooth material

Inference Tooth Mass Discrepancy:

• 0-2.5mm – Proximal stripping
• 2.5-5mm – Extraction of 2nd premolars
• > 5 mm – Extraction of 1st premolars

Question 2. Ashley Howe’s analysis.
Answer.

Methods Of Ashley Howe’s Analysis:

• Determination of total tooth material [TTM] – mesiodistal width of teeth from 1st molar to 1st molars
• Determination of premolar diameter [PMD] – arch width from the tip of the buccal cusp of 1st premolar that of the opposite side
• Determination of premolar basal arch width [PMBAW] – width from canine fossa of one side to other

Interference Of Ashley Howe’s Analysis:

• PMBAW%
• 37 or less – Need for extraction
• 44 or more – Non-extraction
• 37 to 44 – Borderline cases

Question 3. Carey’s analysis.
Answer.

Methods Of Carey’s analysis:

• Determination of arch length – From anterior of first permanent molar to mesial surface of opposite first permanent molar
• Determination of tooth material – mesiodistal width of teeth from 2nd premolar to 2nd premolar
• Determination of the discrepancy – Difference between arch length and tooth material
  • Interference:
    • 0-2.5mm – Proximal stripping
    • 2.5-5mm – Extraction of 2nd premolars
    • > 5mm – Extraction of 1st premolars

Question 4. Peck and peck ratio.
Answer.

• It is based on the concept of stability of rotational corrections of lower incisors rather than tooth size considerations
• It is calculated as
  • Peck and peck ratio = Mesiodistal width / Faciolingual diameter x 100
• The normal ratio for central incisors is 88-92% and for lateral incisors is 90-95%
• This ratio is used to determine whether lower incisor teeth are excessively wider mesiodistally or not

Question 5. Tanaka-Johnston analysis.
Answer.

• Tanaka-Johnston analysis is a mixed dentition analysis
• It predicts the widths of unerupted canines and premolars based on the sum of the width of lower incisors

Methods Of Tanaka-Johnston Analysis:

• Measure the total arch length
• Measure the mesiodistal width of the lower four incisors and sum them up
• Divide the value obtained by 2 and
• Add 10.5 mm to obtain the sum of widths of mandibular canines and premolars in one quadrant
• Add 10.5 mm to obtain the sum of widths of maxillary canines and premolars in one quadrant
• The formula to calculate the space available is
  • Space available = Total arch length – Sum of the lower incisors + 2 x Calculated width of canine and premolar

Advantages Of Tanaka-Johnston Analysis:

• Simple and practical
• Accurate
• Require neither radiographs nor reference tables

Question 6. Korkhaus analysis.
Answer.

• Korkhaus in 1938 proposed a study model analysis that reveals anteroposterior malpositioning of incisors in maxillary and mandibular arches
• A measurement is made from the midpoint of the inter-premolar line to a point between the two maxillary incisors
• According to Korkhaus, for a given width of upper incisors, a specific value of the distance between the two maxillary incisors should exist
• An increase in this measurement denotes proclined upper anterior teeth while a decrease in this value denotes reclined upper anterior teeth

Model Analysis Viva Voce

• Bolton’s analysis proposes that tooth size abnormalities cause malocclusion
• Pont’s analysis indicates the need for expansion rather than extraction
• Peck and Peck is a model analysis of mandibular arch
• Ashley and Howe’s analysis indicates tooth extraction if the premolar basal arch width is less than 37%

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.