Orthodontics

Fixed Appliances Important Notes

• Components of fixed appliances

Fixed Appliances Long Essay

Question 1. Classify orthodontic appliances and discuss in detail the various components of fixed appliances. Add a note on its advantages and disadvantages.
Answer.

Classification Of Orthodontic Appliances:

• Mechanical appliances
  • Removable appliances
  • Fixed appliances
• Myofunctional appliances
  • Removable appliances
  • Fixed appliances

Components Of Fixed Appliances

Active components:

• Archwires
  • Bring about tooth movement
    Ideal requirement:
  • High spring back
  • Low stiffness
  • High formability
  • High resilience
  • Bio-compatible
  • Resist to tarnish and corrosion
  • Can be soldered/welded
  • Least friction creating
    Classification:
    • Based on material
      • Gold and Gold alloys
      • Stainless steel
      • Nickel titanium
    • Based on Cross section
      • Round
      • Rectangular
      • Square
      • Multistranded

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

Elastics:

• Simple elactic – Resemble rubber band
  • Made of latex rubber
  • Available – various diameters and colors
    Use:
    • Closure of space
    • Correcting of open bites
    • Correction of cross bites
    • Correction of inter arch relationship
• Elastic chain
  • Material – Polyurethane
  • Use – Closure of Space between teeth
• Elastic thread
  • Material – Core of latex rubber, surrounded by silk
  • Use – Closure of space, Derotation
• Elastic modules – Two rings separated by variable distance
  • Use – Closure of space and derotation
• Ligating rings
  • Use – To secure arch wires to brackets

Springs:

Use: To bring about tooth movement

Types Of Orthodontic Appliances:

• Uprighting – to move the root mesially
• Torquing – Move root labially/palatally
• Open coil springs – To open space between teeth
• Closed coil springs – To close space

Separators:

Uses Of Separators: To break tight contact

Types Of Separators:

• Brass wire
• Ring
• Dumbbell
• Kesling

Passive Component:

• Bands:
  Use – To fix various attachments to tooth
  Advantage:
  • Reduces chair time
  • Comfortable for patient

        Available:

• • In various sizes for different teeth
  • Of stainless steel
• Brackets:
  • Use – To transmit force to teeth
    Type:
    • Edge wise
    • Ribbon arch
    • Weladable and bondable
    • Metallic
    • ceramic
    • Plastic
• Available – In various sizes
• • Have one/more slots to accept arch wire

Buccal Tubes:

• Fixed on anteriors/premolar
• On molar called molar tube
• Can be welded/bonded/cemented
• Can be round/rectangular
• Additional tubes for extra-oral anchorage
• Lingual Attachments:
  • Attachments fixed on lingual aspect
    Example: Lingual buttons, lingual cleats, eye lets and ball end hook
• Ligature Wires:
  • Use – To secure arch wire
  • Size – 0.009 – 0.011 inched diameters
  • Available in various colors
  • Used in edge wise brackets
• Lockpins:
  • use – To secure ribbon arch brackets
  • Made of brass

Advantages Of Fixed Appliances.

• Cooperation of patient is achieved
• Various tooth movements are possible
• Tooth movement of multiple teeth is possible simultaneously
• Good occlusion is achieved
• More precise tooth movements possible
• Can be used in complicated malocclusions
• Better anchorage is obtained
• Management of appliance possible
• Convenient for the operator as no need of timely wear of appliance
• Less time of treatment required

Disadvantages Of Fixed Appliances.

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

Fixed Appliances Short Essays

Question 1. Name 3 fixed appliace techniques. Differntiate begg and Edgewise appliances.
Answer.

Fixed Appliance Techniques:

• Edgewise technique
• Begg appliance
• Lingual technique

Question 2. Passive Components of Fixed Appliances.
Answer.

Bands Of Fixed Appliances:

Use – To fix various attachments to tooth

• Advantage:
• • Reduces chair time
  • Comfortable for patient
• Available:
  • In various sizes for different teeth
  • Of stainless steel

Brackets Of Fixed Appliances:

Use – To transmit force to teeth

Types Of Brackets:

• Edge wise
• Ribbon arch
• Weladable and bondable
• Metallic
• ceramic
• Plastic

Available – In various sizes

• Have one/more slots to accept arch wire

Buccal Tubes:

• Fixed on anteriors/premolar
• On molar called molar tube
• Can be welded/bonded/cemented
• Can be round/rectangular
• Additional tubes for extra-oral anchorage

Lingual Attachments:

• Attachments fixed on lingual aspect
  Example: Lingual buttons, lingual cleats, eye lets and ball end hook

Ligature Wires:

• Use – To secure arch wire
• Size – 0.009 – 0.011 inched diameters
• Available in various colors
• Used in edge wise brackets

Lockpins:

• use – To secure ribbon arch brackets
• Made of brass

Fixed Appliances Short Questions And Answers

Question 1. Fixed Appliances.
Answer.

Appliances that are fixed/fitted onto the teeth by the operator and cannot be removed by the patient at will are called “Fixed appliances”

Important Advantages Of Fixed Appliances:

• Patient cooperation
• Capable of all tooth movements
• Capable of even root movements

Disadvantages Of Fixed Appliances:

• Poor oral hygiene maintenance
• Time consuming
• Technique sensation

Question 2. Elgiloy Wires.
Answer.

Chemical Name: Cobalt Chromium Nickel

Properties Of Elgiloy Wires:

• Adequate spring back
• Formability
• Biocompatible
• Arch wires – Active component of fixed appliance

Question 3. Molar Tubes.
Answer.

• Fixed on anteriors/premolar
• On molar called molar tube
• Can be welded/bonded/cemented
• Can be round/rectangular
• Additional tubes for extra-oral anchorage

Question 4. Parts of Fixed Appliances.
Answer.

• Active components:
  • Archwires
  • Elastics
  • Springs
  • Separators
• Passive components:
  • Bands
  • Brackets
  • Buccal tubes
  • Lingual attachments
  • Ligature wires
  • Lockpins

Question 5. Stainless Steel.
Answer.

• Austenitic stainless steel
• Use – To make orthodontic archwires

Properties Of Stainless Steel:

• Adequate strength
• Adequate spring back
• Resilience
• Formability
• Biocompatible
• Economical

Fixed Appliances Viva Voce

• Brackets are fixed on anterior teeth and premolars
• Buccal tubes are used on molars
• Elastic chains are made of polyurethane
• Zinc phosphate can be used for cementatin of bands onto the teeth
• Oral hygiene maintenance is difficult in case of fixed appliances
• Plastic brackets are made up of poly carbonate
• Titanium arch wires exhibit superior elastic properties
• Lock pins are made of brass
• Buccal tube is passive component of fixed appliance

Removable Appliances Important Notes

Components of removable appliances

Methods of activation of different components

Types of labial bows

Types of springs

Removable Appliances Long Essays

Question 1. Classify orthodontic appliances and discuss in detail the various active components of removable appliances.
Answer.

Classification Of Orthodontic Appliances:

• Mechanical: Exerts mild pressure on the tooth
  • Removable appliances
  • Fixed appliances
    Myofunctional: Harness natural muscular forces

• • Removable appliance
  • Fixed appliance

Active Components Of Removable Appliances:

Bows

• Used for incisor retraction

Types Of Bows:

• Short labial bow: Parts
  • Bow
  • ‘U’ loop
  • Retentive arms distal to the canine
    Uses:
  • Minor overjet reduction
  • Anterior space closure
  • For retention after fixed mechanotherapy

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Activation: Compressions of U loops

• Long labial bow: Extends from one 1st premolar to the opposite side
  Indications:
  • Minor anterior space closure
  • Overjet reduction
  • Retaining device
  • Closure of space distal to canine
• Split labial bow:
  • Labial bow split in the middle
  • Have separate buccal arms
    Indications:
  • Midline diastema
  • For anterior retraction

• Reverse labial bow: Free ends of U loops adapted occlusal
  Activation:
  • Opening of U loop
  • Compensatory bend at the base of U

• Others:
  • Robert’s retractor
  • Mills retractor
  • High labial bow with apron springs
  • Fitted labial bow

Springs

Classification:

• Based on the presence/absence of helix
  • Simple without helix
  • Compound with helix
• Based on the presence of loops/helix
  • Helical springs
  • Looped springs
• Based on the nature of the stability of spring
  • Self-supported
  • Supported

Screws:

• To bring about different tooth movement

Example:

• Arch expansion
• Buccal movement of teeth
• Mesial/distal movement of teeth

Elastics:

• For anterior retraction
• May cause gingival trauma

Removable Appliances Short Essays

Question 1. Adam’s clasp and its modifications.
Answer.

• By Professor Phillip Adams

Synonyms Of Adam’s Clasp:

• Liver pool clasp
• Universal clasp
• Modified arrow head clasp

Wire Used:

• 0.7 mm round stainless steel

Parts:

• Two arrowheads – Engaging proximal undercuts
• Bridge – Connects two arrowheads

Two Retentive Arms – Incorporated In Acrylic

Advantages Of Adam’s Clasp:

• Rigid retentive
• Simple to fabricate
• Occupies minimum space
• Can be used for
  • Deciduous and permanent teeth

• • Partially and fully erupted teeth
  • Incisors, premolars and molars
    • Modified in many ways

Modifications Of Adam’s Clasp:

• Adams with single arrowhead
• Adams with additional arrowhead
• Adams with J hook
• Adams with incorporated helix
• Adams with soldered buccal tube
• Adams with distal extraction
• Adams on incisors and premolars

Question 2. Canine retractors.
Answer.

U loop canine retractor:

• Wire used – 0.6/0.7 mm

Parts Of U loop canine retractor:

• U loop: Base is 2-3 mm below the cervical margin
• Active arm:
  • Bent at right angles
  • Passed below mesial contact point of canine
• Retentive arm: Incorporated in acrylic
  Uses: In 1-2 mm of retraction

Helical canine retractor:

• Wire – 0.6mm

Parts Of Helical canine retractor:

• Coil – 3mm diameter
• Active arm – towards tissue
• Retentive arm

Activation: Opening of helix

Use: In shallow sulcus

Palatal canine retractor:

• Wire – 0.6mm

Parts:

• Coil – 3mm diameter
• Active arm – mesial to canine
• Guide arm

Use: Retraction of palatally placed canine

Buccal canine retractor:

Uses Of Buccal Canine Retractor:

• Bucally placed canines
• Highly placed canines

Parts Of Buccal Canine Retractor:

• Coil – 3mm diameter
• Active arm – away from tissue
• Retentive arm

Types Of Buccal Canine Retractor:

• Supported – with 0.5mm wire
• Self-supported – with 0.7 mm wire

Question 3. Advantages and disadvantages of removable appliances.
Answer.

Advantages Of Removable Appliances:

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

Disadvantages Of Removable Appliances:

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

Removable Appliances Short Questions And Answers

Question 1. Z spring/Double cantilever.
Answer.

Uses Of Z spring:

• Labial movement of incisors
• Minor rotation of incisors

Wire used: 0.5 mm

Parts Of Z spring:

• Two coils
• Retentive arm – 10-12 mm length

Activation Of Z spring:

• Opening of helix
• One helix for rotation
• Both helices for labial movement

Question 2. Finger Springs/Single Cantilever.
Answer.

• One end is fixed and the other end is free

Wire used: 0.5/0.6mm

• Use
• Mesio distal movement of teeth

Parts Of Finger Springs:

• Active arm – 12-15mm length
• Helix – 3mm diameter
• Activation – Moving active arm towards teeth

Question 3. Cantilever Springs.
Answer.

Double cantilever:

Uses Of Double Cantilever:

• Labial movement of incisors
• Minor rotation of incisors

Wire used: 0.5mm

Parts Of Double Cantilever:

• Two coils
• Retentive arm – 10-12mm length

Finger Springs/Single Cantilever:

• One end is fixed and the other end is free

Wire Used: 0.5/0.6mm

Uses Of Finger Springs:

• Mesio distal movement of teeth

Parts Of Finger Springs:

• Active arm – 12-15mm length
• Helix – 3mm diameter
• Activation – Moving active arm towards teeth

Question 4. Canine Retractor.
Answer.

• Used for distalization of canines

Types Of Canine Retractors

U loop canine retractor:

• Wire used – 0.6/0.7mm
• Uses: In 1-2mm of retraction

Helical canine retractor:

• Wire – 0.6mm
• Use: In shallow sulcus

Palatal canine retractor:

• Wire – 0.6 mm
• Use: Retraction of palatally placed canine

Buccal canine retractor:

Uses Of Buccal Canine Retractor:

• Bucally placed canines
• Highly placed canines

Types Of Buccal Canine Retractor:

• Supported – with 0.5mm wire
• Self-supported – with 0.7 mm wire

Question 5. Adam’s clasp and its advantages
Answer.

• By Professor Phillip Adams

Synonyms Of Adam’s Clasp:

• Liver pool clasp
• Universal clasp
• Modified arrow head clasp

Wire Used:

• 0.7 mm round stainless steel

Parts Of Adam’s Clasp:

• Two arrowheads – Engaging proximal undercuts
• Bridge – Connects two arrowheads

Two Retentive Arms – Incorporated In Acrylic:

Advantages Of Adam’s Clasp:

• Rigid retentive
• Simple to fabricate
• Occupies minimum space
• Can be used for
  • Deciduous and permanent teeth
  • Partially and fully erupted teeth
  • Incisors, premolars and molars

Removable Appliances Viva Voce

• T spring is activated by pulling the free end of the T
• Labial movement of incisors is achieved by Z spring
• Buccal movement of premolars and canines is achieved by T spring
• U loop canine retractor is activated by compressing the loop
• Finger spring is a single cantilever
• Z spring is also called a double cantilever
• A modified split labial bow is used for the closure of midline diastema
• The palatal canine retractor is activated by opening the helix by 2mm
• Adam’s clasp is most commonly used
• The reverse labial bow is activated by opening the U-loop
• The finger spring is activated by opening the helix
• Z spring is activated by opening both helices simultaneously

Extractions Important Notes

Wilkinson’s extraction

• It involves the extraction of all the four permanent molars between the age of 8 1/2 to 9 years
• It is done to
  • Minimize arch crowding
  • Provide addition space for eruption of third molars
• Basic is that the first permanent molars are highly susceptible to caries

Extractions Short Essays

Question 1. Second Premolar extraction for treatment purposes.
Answer:

Indications Of Second Premolar Extraction:

• To strengthened anchorage of anterior segment
• For mesial movement of posterior teeth
• Treat mild anterior crowding
• When 4-5mm of anchorage loss is desired
• Impacted 2nd premolars
• In open bite – as it results in deepening of bite
• In case of grossly carious/extensive restored teeth
• Early loss of deciduous molars which leads to inadequate space for 2nd premolar to erupt
• When arch length-tooth material discrepancy is 2.5-5 mm

Question 2. First premolar extractions.
Answer:

Reasons Of First Premolar Extractions

• To gain space to utilized for correction
• Satisfactory contact between canine and 2nd premolar
• Teeth posterior to it offers adequate anchorage

Indications Of First Premolar Extractions:

• To relieve moderate – severe anterior crowding
• For correction of class 2, division 1 and Class 1 bimaxillary protrusion
• In case of > 5 mm arch length tooth material discrepancy

Question 3. Therapeutic Extractions.
Answer:

Extractions carried out as a treatment procedure for gaining space are called therapeutic extractions

Need for Extraction:

• Arch length – tooth material discrepancy
• Correction of saggital interarch relationship
• Abnormal tooth size and form
• Skeletal jaw malrelation

Choice Of Teeth – Common Premolars:

Factors Of Therapeutic Extractions:

• Arch length tooth material discrepancy
• Direction and amount of jaw growth
• Facial profile
• Tooth position
• Age of patient

Disadvantages Of Therapeutic Extractions:

• Mesial migration of posterior teeth
• De-crowding of lower anteriors – following extraction of lower 1st premolar

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

• Buccal non-occlusion
• Non coincidence of mid lines

Prevented By:

• Balaced extraction

Question 4. Wilkinson’s Extraction.
Answer.

• Advocated by Wilkinson
• Teeth extracted – All permanent 1st molars
• Age – 8 1/2-9 1/2 years

Benefits – Minimizes Crowding:

• Provides space for the third molar eruption
• Decreases risk of caries

Draw Backs:

• Limited space to relieve crowding
• Tipping of second premolar and 2nd molar
• First molar unable for anchorage

Extractions Viva Voce

• Maxillary first molar is the most commonly extracted teeth
• Maxillary anterior are least extracted

Methods Of Gaining Space Important Notes

• Proximal stripping
  • Contraindications
    • Young patients
    • Patient with high caries index
• Methods of Gaining Space
  • Proximal stripping
  • Expansion
  • Extraction
  • Distalization
  • Uprighting of molars
  • Derotation of posteriors
  • Proclination of interiors

Methods Of Gaining Space Long Essays

Question 1. What are therapeutic methods of gaining space? Explain in detail first premolar extraction.
Answer.

Methods Of Gaining Space:

• Proximal stripping
• Expansion
• Extraction
• Distalization
• Uprighting of molars
• Derotation of posteriors
• Proclination of interiors

First Premolar Extraction:

• Extraction forms a main part of all space-gaining procedures
• Extraction is indicated for the correction of
  • Crowding
  • Anteroposterior dental arch relations
  • Vertical problems
  • Skeletal jaw deformities
  • Presence of supernumerary teeth
• Factors affecting the choice of teeth
  • Condition of teeth
  • Position of teeth
  • Position of crowding
• Premolars are frequently extracted for this purpose

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

First Premolar Extractions:

Reasons:

• To gain space to utilize for correction
• Satisfactory contact between canine and 2nd premolar
• The teeth posterior to it offer adequate anchorage

Indications Of First Premolar Extractions:

• To relieve moderate-severe anterior crowding
• For correction of class 2, division 1, and class 1 bimaxillary protrusion
• In case of > 5mm arch length tooth material discrepancy

Question 2. Explain various methods of gaining space.
Answer.

Proximal stripping:

Synonyms Of Methods Of Gaining Space:

• Approximation
• Slenderization
• Disking and Proximal slicing

Procedure Of Methods Of Gaining Space:

• Proximal surfaces are sliced to reduce the mesiodistal dimensions of teeth

Means:

• Metallic abrasive strips
• Carborundum discs
• Long thin tapered fissure burs
  • Followed by fluoride application

Indications Of Methods Of Gaining Space:

• 0-2.5mm – Discrepancy
• Mild to moderate excess tooth material according to Bolton’s analysis

Contraindications Of Methods Of Gaining Space:

• Young patients
• High caries index
  • Amount of reduction – less than 50% of enamel

Expansion:

Indications Of Expansion:

• Constricted maxillary arch
• Unilateral/Bilateral crossbite

Types Of Expansion:

• Skeletal
  • By splitting mid palatal suture
• Dental
  • By jackscrew/springs like coffin spring

Extraction:

• Commonly extracted are premolars
• Provides sufficient space for correction
• Preserves functions and esthetics

Visualization of molars:

• Advantage – Avoids the need for extraction
• Indication – Mild to moderate class 2
• Time – Before the eruption of 2n permanent molar

Uprighting of molars:

• Indication: Mesially tipped molar
• Causes: Premature loss of 2nd deciduous molar
• Extraction of 2nd premolar

Appliances used:

• Molar uprighting springs
• Space regainers

Derotation of Posteriors:

• Rotated posteriors occupy more space
• Derotation of them helps to gain space
• Appliances used:

Incorporating springs/elastics using a force couple

Proclination of interiors:

• Indication: Retroclined interiors
• Precaution: Prevent damage to the soft tissue profile

Methods Of Gaining Space Short Essays

Question 1. Slenderization/Proximal Stripping.
Answer.

Proximal stripping:

• Synonyms:
  • Approximation
  • Slenderization
  • Disking and Proximal slicing
• Procedure:
  • Proximal surfaces are sliced to reduce the mesiodistal dimensions of teeth
• Means:
  • Metallic abrasive strips
  • Carborundum discs
  • Long thin tapered fissure burs
    • Followed by fluoride application
• Indications:
  • 0-2.5mm – Discrepancy
  • Mild to moderate excess tooth material according to Bolton’s analysis
• Contradictions:
  • Young patients
  • High caries index
  • Amount of reduction: less than 50% of enamel

Expansion:

• Indications Of Expansion:
  • Constricted maxillary arch
  • Unilateral/Bilateral crossbite
• Types Of Expansion:
  • Skeletal
    • By splitting mid palatal suture
  • Dental
    • By jackscrew/springs like coffin spring

Extraction:

• Commonly extracted are premolars
• Provides sufficient space for correction
• Preserves functions and esthetics

Visualization of molars:

• Advantage – Avoids the need for extraction
• Indication – Mild to moderate class 2
• Time – Before the eruption of 2nd permanent molar

Uprighting of molars:

• Indication: Mesially tipped molar
• Causes: Premature loss of 2nd deciduous molar
• Extraction of 2nd premolar

Appliances used:

• Molar uprighting springs
• Space regainers

Derotation of posteriors:

• Rotated posteriors occupy more space
• Derotation of them helps to gain space
• Appliances used:
• Incorporating springs/elastics using a force couple

Proclination of interiors:

• Indication: Retroclined interiors
• Precaution: Prevent damage to the soft tissue profile

Question 2. Slenderization/Proximal Stripping.
Answer.

Synonyms Of Proximal Stripping:

• Approximation
• Slenderization
• Disking and Proximal slicing

Procedure Of Proximal Stripping:

• Proximal surfaces are sliced to reduce the mesiodistal dimensions of teeth

Means:

• Metallic abrasive strips
• Carborundum discs
• Long thin tapered fissure burs
  • Followed by fluoride application

Indications Of Proximal Stripping:

• 0-2.5mm – Discrepancy
• Mild to moderate excess tooth material according to Bolton’s analysis

Contraindications Of Proximal Stripping:

• Young patients
• High caries index
• Amount of reduction: Less than 50% of enamel

Question 3. Molar distalization
Answer.

Aim: To move molars in a distal direction to gain space

Methods Of Molar distalization:

• Extraoral headgear
• Intra oral Sagittal appliance
  • Intraoral magnets
  • Open coil spring
  • Pendulum appliance
• Headgear
  • Consists of a face bow with an inner and outer bow
  • Head cap/neck strap

Disadvantage Of Molar distalization:

• Needs patient cooperation
• Has intermittent in their action

Sagittal Appliance:

• Consist of jackscrew positioned parallel to the occlusal plane
• Use only one tooth at a time

Intra-oral magnets

• Consists of repelling magnets

Open coil spring:

• Compressed spring placed between molar and anterior segment

Pendulum appliance:

• Consist of modified Nance button and helix
• Activated by opening the helix

Methods Of Gaining Space Short Questions And Answers

Question 1. Derotations.
Answer.

• Rotated posteriors occupy more space
• Derotation of them helps to gain space
• Appliances used
• Incorporating springs/elastics using a force couple

Question 2. Enumerate methods of Gaining Space.
Answer.

• Methods of Gaining Space
  • Proximal stripping
  • Expansion
  • Extraction
  • Distalization
  • Uprighting of molars
  • Derotations of posterior teeth
  • Proclination of anterior

Methods Of Gaining Space Viva Voce

• Visualization is an advanced method of gaining space in recent times
• A mixed dentition period before the eruption of the second permanent molar is the ideal time for distalization
• Proximal stripping requires space of 0-2.5mm
• Bolton’s analysis is done for proximal stripping
• Proclination of interiors creates space
• Slenderization is also called approximation, disking, and proximal slicing

Interceptive Orthodontics Definitions

• Interceptive orthodontics:
  • It is defined as that phase of the science and art of orthodontics employed to recognize and eliminate potential irregularities and malpositions of the developing dentofacial complex.
• Preventive orthodontics:
  • According to Graber, it is defined as the action taken to preserve the integrity of what appears to be a normal occlusion at a specific time.
• Serial extraction:
  • It is a procedure that includes the planned extraction of certain deciduous teeth and later specific permanent teeth in an orderly sequence and pre-determined pattern to guide the erupting permanent teeth into a more favorable position.
• Space regainer:
  • Appliances used to regain the space lost by the mesial movement of the molar due to premature loss of deciduous, by distal movement of the first molar are called “Space Regainers”.

Interceptive Orthodontics Important Notes

• Serial extraction
  • Indications:
    • Skeletal class 1
    • Flaring of teeth
    • Localized gingival recession in lower anterior
    • Ectopic eruption of teeth
    • Unilateral/bilateral premature loss of deciduous canines
    • Discrepancy should be at least 5 mm
  • Contra-Indications:
    • Class 2 and 3 malocclusions
    • Open bite and deep bite
    • Midline diastema
    • Class 1 with minimum space deficiency
  • Types:
    • Dewey’s method
      • The most commonly used method
      • Extraction of deciduous canine is done at the age of 8-9 years
      • Followed by extraction of the erupting first premolar
    • Tweed’s method – D4C
• Exercises for different muscles:

Interceptive Orthodontics Long Essays

Question 1. Define Serial Extraction, and explain its indications, contraindications, and methods.
Answer.

Interceptive Orthodontics:

It is defined as that phase of the science and art of orthodontics employed to recognize and eliminate potential irregularities and malpositions of the developing dentofacial complex.

Serial Extraction:

Definition: It is a procedure that includes the planned extraction of certain deciduous teeth and later specific permanent teeth in an orderly sequence and predetermined pattern to guide the erupting permanent teeth into a more favorable position.

Indications Of Serial Extraction:

• Class 1 malocclusion with normal muscle activity
• Deficient arch length
• Absence of primate spacing
• Premature loss of deciduous canines
• Impacted lateral incisors
• Crowded interiors
• Localized gingival recession
• Ectopic eruption of teeth
• Mesial migration of posteriors
• Abnormal sequence of eruption
• Lower anterior flaring
• Ankylosed teeth
• Deficient growth
• Straight profile persons

Contraindications Of Serial Extractions:

• Skeletal Class 2 and 3
• Spacing
• Anodontia
• Open bite/Deep bite
• Midline spacing

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

• Dilacerated tooth
• Extensive carious/restored tooth
• Mild discrepancy

Methods

Dewel’s Method:

Tweed’s method:

Nance method:

• Similar to Tweed

Question 2. Define Preventive and Interceptive Orthodontics. Explain various methods of interceptive orthodontics.
Answer.

Definition:

Preventive Orthodontics: According to Graber it is defined as the action taken to preserve the integrity of what appears to be a normal occlusion at a specific time.

Interceptive Orthodontics: It is that phase of the science and art of orthodontics employed to recognize and eliminate potential irregularities and mal-positions of the developing dento facial complex.

Procedures Of Interceptive Orthodontics:

Serial extraction:

• It is planned extraction of certain deciduous teeth and later specific permanent teeth in orderly sequence and predetermined pattern
  • Rationale:
    • Arch lenght tooth material discrepancy
    • Physiologic tooth movement
  • Advantage:
    • Physiologic
    • More stable
    • Less retention required
    • Less psychological trauma
    • Healthy gingival tissue
  • Disadvantage:

Lengthy Procedure:

• Need of fixed mechano therapy
• Patient’s cooperation

Procedure:

Dewel’s method [CD4]:

• Step 1 – Extraction of deciduous canine [C]
  • For alignment of incisor
• Step 2 – Extraction of deciduous first [D]
  • To accelerate eruption of 1st PM
• Step 3 – Extraction of 1st PM [U]
  • To permit eruption of permanent canine

Tweed’s method [DC4]:

Nance’s method: Similar to Tweeds

Developing Anterior cross bite:

Significance: Treated to prevent minor orthodontic problem

Reason to treat:

• May manifest in permanent dentition
• May lead to skeletal malocclusion

Types Treatment/Appliances:

• Functional Eliminating occlusal prematurities
• Dento-alveolar Tongue blade, Catlan’s appliance
• Skeletal Myofunctional appliances

Interception of habits:

• Habit effecting dento-alveolar segment
  • Thumb sucking
  • Tongue thrusting
  • Mouth breathing
• Habit breaking appliances are used

Space Regaining:

• Space lost by mesial movement of molar can be regained by distal mivement of 1st molar.

Age: At early age

Appliance used:

• Gerber space regainer
• Jackscrew
• Cantilever spring

Muscular Exercises:

• Normal occlusal depends on the surrounding perioral musculature

Use:

• Muscle exercise help to improve aberrant muscle function

Interception of skeletal malrelations:

Importance: Reduces severity of disease

For class 2: Head gear is used

For class 3: FR 3/face mask therapy

Removal or soft tissues and bony barriers:

Question 3. Serial Extraction.
Answer.

Serial Extraction:

It includes the planned extraction of certain deciduous teeth and later specific permanent teeth in an orderly sequence and pre-determined pattern to guide the erupting permanent teeth into a more favorable position.

Basic Principles:

• Arch length tooth discrepancy
• Physiologic tooth movement

Serial Extraction Indications:

• Class 1 malocclusion
• Arch length deficiency
• Absence of primate spaces
• Mal-positioned/Impacted lateral incisors
• Markedly irregular/crowded anteriors
• Localized gingival recession
• Ectopic eruption
• Mesial migration
• Lower anterior flaring

Serial Extraction Contra-Indications:

• Class 2 and 3 malocclusion
• Spaced dentition
• Open bite and deep bite
• Mid line diastema
• Anodontia/Oligodontia
• Un-erupted teeth
• Extensive caries

Serial Extractions Advantages:

• More physiologic
• Less Psychological trauma
• Less duration
• Better oral hygiene
• Preserve gingival health
• Less retention required
• More stable

Serial Extractions Disadvantages:

• Prolonged treatment
• Patient co-operation
• Development of habits
• Deepening of bite
• Require fixed appliance therapy

Procedure:

Dewel’s:

• Step 1 – Extraction of deciduous canine [C]
  • For alignment of incisor
• Step 2 – Extraction of deciduous first [D]
  • To accelerate eruption of 1st PM
• Step 3 – Extraction of 1st PM [U]
  • To permit eruption of permanent canine

Tweed’s method [DC4]:

Interceptive Orthodontics Short Essays

Question 1. Serial extraction and write about its indications.
Answer.

Serial Extraction:

It includes the planned extraction of certain deciduous teeth and later specific permanent teeth in an orderly sequence and pre-determined pattern to guide the erupting permanent teeth into a more favourable position.

Basic Principles:

• Arch length tooth material discrepancy
• Physiologic tooth movement

Serial Extraction Indications:

• Class 1 malocclusion
• Arch length deficiency
• Absence of primate spaces
• Mal-positioned/Impacted lateral incisors
• Markedly irregular/crowded anteriors
• Localized gingival recession
• Ectopic eruption
• Mesial migration
• Lower anterior flaring

Question 2. Interceptive Orthodontic Management of Maxillary Retrusion.
Answer.

Myofunctional appliance/face mask therapy is used to promote maxillary growth

Anchorage Site:

• Chin
• Skull
• Chin and Forehead together

Principle Of Maxillary Retrusion:

• Creates pulling force on maxillary structure
• Reciprocal pushing force on mandible/forehead

Parts Of Maxillary Retrusion:

• Chin cup: Takes anchorage from chin area – connected to face mask assembly by metal rods
• Forehead cap: Derive anchorage from forehead
• Elastics: Applies forward traction on upper arch
• Intraoral appliance: Consists of traction hooks on molars
• Metal Frame: Connects various components
• Receives elastic from intraoral appliance

Interceptive Orthodontics Short Questions And Answers

Question 1. Space Regainers.
Answer.

Appliances used to regain the space lost by mesial movement of molar due to premature loss of deciduous, by distal movement of the first molar are called “Space Regainers”.

Time: At early age

• Prior to eruption of second molar

Examples:

• Gerber Space Regainer
• Jack Screws
• Cantilever Springs

Question 2. Advantages of Serial Extraction.
Answer.

Physiological Procedure:

• Less psychological trauma
• Reduce treatment duration
• Maintenance of oral hygiene
• Preservation investing tissues
• Less retention required
• More stable

Question 3. Disadvantages of Serial Extraction.
Answer.

• Not universally applicable
• Prolonged treatment time
• Frequent visit required
• Development of habit
• Risk of reduction in arch length
• Creation of space between canine and 2nd premolar
• Requires short term fixed mechano therapy

Question 4. Interceptive orthodontic procedures.
Answer.

• Interceptive orthodontic procedures are
  • Serial extraction
  • Developing anterior crossbite
  • Interception of habits
  • Space regainer
  • Muscular exercise
  • Interception of skeletal malrelation

Interceptive Orthodontics Viva Voce

• Button pull exercise is done for lips
• Stretching of upper lip to maintain lip seal is therapeutic measure for short hypotonic lips
• Tug of war exercise is good exercise for lips
• One elastic swallow and two elastic swallow is for tongue
• Hold pull exercise is helpful in stretching the lingual frenum
• Serial extraction is crried out when space needed is 5-7mm
• First tooth to be extracted in Dewel’s method is deciduous canine
• First tooth to be extracted in tweed’s method is deciduous first molar
• Midline diastema is contraindication of serial extraction

Preventive Orthodontics Important Notes

Classification of space maintainers:

• According to Hitchcock:
  • Removable/Fixed/Semi-fixed
  • With bands/without bands/
  • Functional/non-functional
  • Active/Passive
  • Combinations
• According to Raymond:
  • Removable
  • Complete arch
  • Individual tooth
• According to Hinrechsen:
  • Fixed
    • Class 1 – Non-functional
    • Functional:
    • Class 2 – Cantilever type
  • Removable – Acrylic partial dentures
• Distal shoe space maintainer
  • Indications:
    • Loss of primary 2nd molar before eruption of permanent first molar
  • Contra-indications:
    • Patient with heart disease
    • Patient with poor oral hygiene
    • Haemophilic patients
• Indications of various space maintainers

• Factors considered for space maintainers
  • Time elapsed since loss of teeth
  • Dental age of patients
  • Thickness of be one covering the unerupted teeth
  • Sequence of eruption of teeth
  • Congenital absence of permanent teeth
• Disadvantages of fixed space maintainers
  • Nonfunctional maintainers can cause supra eruption of opposing teeth
  • Functional space maintainer can interfere with vertical eruption of abutment teeth
  • Expert skill and elaborate instrumentation are needed
  • Decalcification of tooth under bands

Preventive Orthodontics Long Essays

Question 1. Define preventive orthodontics. Discuss various preventive orthodontic procedures
Answer.

Definition: According to Graber it is defined as the action taken to preserve the integrity of what appears to be a normal occlusion at a specific time.

Procedures Of Preventive Orthodontics:

• Parent Education: To expected/lactating mothers
• Caries Control: Especially proximal caries – leads to loss of arch
• Care of Deciduous Dentition:
  • Restoring the carious teeth at the proper time
  • To prevent early loss of deciduous
  • Includes – application of topical fluorides
  • Pit and fissure sealants
• Extraction of Supernumerary teeth:
  • As it interferes with the eruption of adjacent teeth
  • Deflects its eruptive path
• Eliminate occlusal interference:
  • As occlusal prematurities deviate path of closure
• Maintenance of tooth shedding timetable:
  • More than 3 months difference should not be present between the shedding of deciduous and eruption of permanent
• Management of Ankylosed teeth:
  • Ankylosed tooth prevents eruption of permanent and deflects their eruption path
  • Thus, they should be removed
• Management of Abnormal Frenal Attachment:
  • Abnormal frenum – leads to mid-line diastema
• Management of Habits:
  • Habits lead to malocclusion
• Management of deeply locked permanent first molars:
  • Prominent distal bulge of deciduous second molars prevents eruption of first permanent molar
• Preventing Milwaukee Brace damage:
  • Milwaukee Brace used for correction of scoliosis
  • But this leads to retardation of the mandible
• Space maintainers:
  • Definition: It is a device used to maintain the space created by the loss of a deciduous tooth.

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

Classifications Of Preventive Orthodontics:

• According to Hitchcock:
  • Removable/Fixed/Semi-fixed
  • With bands/without bands
  • Functional/non-functional
  • Active/Passive
  • Combinations
• According to Raymond:
  • Removable
  • Complete arch
  • Individual tooth
• According to Hinrechsen:
  • Fixed
    • Class 1 – Non-functional
    • Functional:
    • Class 2 – Cantilever type
• Removable – Acrylic partial dentures

Preventive Orthodontics Short Essays

Question 1. Space Maintainers.
Answer.

Definition: It is a device used to maintain the space created by the loss of a deciduous tooth.

Space Maintainers Requirements:

• Maintain the space created
• Restores function
• Prevent supra eruption of opposing teeth
• Simple to construct
• Withstand functional forces
• Do not exert excessive stress
• Maintain oral hygiene
• Allow growth of permanent
• Not interfere during oral functions

Classifications Of Space Maintainers:

• According to Hitchcock:
  • Removable/Fixed/Semi-fixed
  • With bands/without bands
  • Functional/non-functional
  • Active/Passive

• • Combinations
• According to Raymond:
  • Removable
  • Complete arch
  • Individual tooth
• According to Hinrechsen:
  • Fixed:
    • Class 1 – Non-functional
    • Functional
    • Class 2 – Cantilever type
  • Removable – Acrylic partial dentures

Planning:

Depends on:

• Time elapsed
• Dental age enters Sequence of eruption
• Thickness of bone
• Sequence of eruption

Preventive Orthodontics Short Questions And Answers

Question 1. Define Preventive and Interceptive Orthodontics.
Answer.

Preventive Orthodontics:

According to Graber, it is defined as the action taken to preserve the integrity of what appears to be a normal occlusion at a specific time.

Interceptive Orthodontics:

It is defined as that phase of the science and art of orthodontics employed to recognize and eliminate potential irregularities and malpositions of the developing dentofacial complex.

Question 2. Space maintainers.
Answer.

Definition: It is a device used to maintain the space created by the loss of a deciduous tooth.

Space Maintainers Requirements:

• Maintain the space created
• Restores function
• Prevent supra eruption of opposing teeth
• Simple to construct
• Withstand functional forces
• Do not exert excessive stress
• Maintain oral hygiene
• Allow growth of permanent
• Not interfere during oral functions

Question 3. Distal Shoe Space Maintainers.
Answer.

Synonym: Intra-alveolar appliance

Uses:

• Guides the unerupted first permanent molar
• Used in case of premature loss of second primary molar
• Controls path of eruption
• Prevents mesial migration

Preventive Orthodontics Viva Voce

• The crib appliance is placed palatal to the maxillary incisor
• Distal shoe space maintainer is a cantilever type of space maintainer
• Band and loop are the most effective space maintainers in the lower arch
• Preventive orthodontics is undertaken before the development of malocclusion
• Deciduous dentition is a classical example of a natural space maintainer
• Nance holding arch derives its support from the anterior plate
• Crown and loop are preferred when there is a carious tooth adjacent to the space

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%