22. Classification of malocclusion. Angle, Katz, Simon classification of malocclusion

Question 1

22. Classification of malocclusion. Angle, Katz, Simon classification

Malocclusion and why its important to classify

Answer 1

• Misalignment of teeth and/or incorrect relation between the teeth of the two dental arches
• Advantages=>Diagnosis and Treatment Planning
• Visualization and Understanding
• Communication=> between dental professionals.
• Comparison

Question 2

22. Classification of malocclusion. Angle, Katz, Simon classification

Angle’s Classification

Answer 2

• Mesiodistal relation of teeth, arches, and jaws
• Three main classes=>
• Relationship of mesiobuccal cusp of maxillary first molar and buccal groove of mandibular first molar

Question 3

22. Classification of malocclusion. Angle, Katz, Simon classification

Class I Malocclusion

Answer 3

• The mesiobuccal cusp of maxillary first molar occludes w/ buccal groove of mandibular first molar
• May exhibit dental irregularities=>
• Crowding, spacing, rotation, or missing teeth=>
• w/ normal skeletal relation and muscle function
• Includes conditions like bimaxillary protrusion and open-bite

Question 4

22. Classification of malocclusion. Angle, Katz, Simon classification

Bimaxillary protrusion

Answer 4

• Normal class I molar relationship=>
• Dentition of upper and lower arches forwardly placed in relation to facial profile

Question 5

22. Classification of malocclusion. Angle, Katz, Simon classification

Open-bite

Answer 5

• Abnormal perioral muscle function=>
• Normal molar relationship=>
• Teeth anterior to first molar completely out of contact even during full habitual occlusion

Question 6

22. Classification of malocclusion. Angle, Katz, Simon classification

Class II Malocclusion

Answer 6

• Distobuccal cusp of upper first permanent molar occludes w/ buccal groove of lower first permanent molar=>
• Mandibular arch positioned distally or posteriorly to the maxillary arch
• Two(1/2) divisions=>
• Class II div 1, Class II div 2, Class II Subdivision

Question 7

22. Classification of malocclusion. Angle, Katz, Simon classification

Class II Division 1

Answer 7

• Biproclined upper incisors
• Increased overjet
• Deep incisor overbite
• Hypotonic upper lip,
• Characteristic “zip trap” feature

Question 8

22. Classification of malocclusion. Angle, Katz, Simon classification

Class II Division 2

Answer 8

• Retroclined upper central incisors
• Proclined upper lateral incisors
• Deeper anterior overbite
• Exaggerated curve of Spee
• Potential gingival trauma

Question 9

22. Classification of malocclusion. Angle, Katz, Simon classification

Class II Subdivision

Answer 9

Class II molar relation on one side and Class I on the other

Question 10

22. Classification of malocclusion. Angle, Katz, Simon classification

Class III Malocclusion

Answer 10

• Mesiobuccal cusp of maxillary first permanent molar occludes in interdental space between mandibular first and second molars
• True Class III, Pseudoclass III, Class III Subdivision

Question 11

22. Classification of malocclusion. Angle, Katz, Simon classification

True Class III

Answer 11

• Skeletal origin
• Causes =>Large/ forwardly placed mandible or smaller/ retropositioned maxilla

Question 12

22. Classification of malocclusion. Angle, Katz, Simon classification

Pseudoclass III

Answer 12

• Forward movement of mandible during jaw closure=>
• Premature loss of deciduous teeth or enlarged adenoids

Question 13

22. Classification of malocclusion. Angle, Katz, Simon classification

Class III Subdivision

Answer 13

• Class III molar relation on one side and Class I on the other

Question 14

22. Classification of malocclusion. Angle, Katz, Simon classification

Angle’s classification drawbacks

Answer 14

• Limited to Anteroposterior Plane=> transverse and vertical planes not included
• Fixed Point Assumption=>first permanent molars not always fixed point in the skull
• Inapplicability in Certain Conditions=>cannot be applied if first permanent molar extracted or missing
• Or in deciduous (primary) dentition
• Skeletal vs. Dental Malocclusions=>does not differentiate between skeletal and dental malocclusions
• Etiology of malocclusion not defined
• Individual Tooth Malposition=>Individual tooth malpositions not considered

Question 15

22. Classification of malocclusion. Angle, Katz, Simon classification

Katz’ Premolar Classification

Answer 15

Premolar Class I-III

Question 16

22. Classification of malocclusion. Angle, Katz, Simon classification

Premolar class I

Answer 16

• Most anterior upper premolar fits exactly into embrasure created by distal contact of most anterior lower premolar
• Represents perfect interdigitation with a value of 0mm

Question 17

22. Classification of malocclusion. Angle, Katz, Simon classification

Premolar class II

Answer 17

• Most anterior upper premolar occludes mesially of embrasure created by distal contact of most anterior lower premolar
• Measurement has a positive sign (+

Question 18

22. Classification of malocclusion. Angle, Katz, Simon classification

Premolar class III

Answer 18

• Most anterior upper premolar occludes distally of embrasure created by distal contact of most anterior lower premolar
• Measurement has a negative sign (-)

Question 19

22. Classification of malocclusion. Angle, Katz, Simon classification

Simon’s Classification of malocclusion

Answer 19

• Craniometric classification system for malocclusion=>
• Uses anthropometric planes to describe abnormal deviations of dental arches from their normal positions
• Three planes =>
• Frankfurt Horizontal Plane
• Orbital Plane
• Midsagittal Plane

-Anthropometry refers to the measurement of the human individual

Question 20

22. Classification of malocclusion. Angle, Katz, Simon classification

Frankfurt horizontal plane and how is it used in Simon’s Classification

Answer 20

• Reference plane=>connects margin of external auditory meatus to infraorbital margin
• Classifies malocclusions in vertical plane=>
• Attraction=>dental arch or part of it closer to Frankfurt horizontal plane than normal
• Abstraction=>dental arch or part of it further away from Frankfurt horizontal plane than normal

Question 21

22. Classification of malocclusion. Angle, Katz, Simon classification

How orbital plane contributes to Simon’s Classification

Answer 21

• Perpendicular to Frankfurt horizontal plane=>
• From bony orbital margins under pupil of eye=>
• Through distal third of upper canines=>
• “Simon’s Law of Canine.”
• Describes malocclusions in sagittal (anteroposterior) plane
• Protraction=>dental arch or part of it away from orbital plane
• Retraction=> dental arch or part of it closer to or placed more posteriorly to orbital plane

Question 22

22. Classification of malocclusion. Angle, Katz, Simon classification

Midsagittal plane and how it helps classify malocclusion in Simon’s system

Answer 22

• Describes malocclusion in transverse plane=>
• Divides body into left and right halves
• Contraction=>dental arch or part of it close to midsagittal plane
• Distraction=>dental arch or part of it away from midsagittal plane