Occlusion: It is the static relationship between occlusal surface of maxillary and mandibular teeth or tooth.

Malocclusion: Any deviation from a physiologically acceptable contact of opposing dentition.

Classification: The description of dento facial deviations according to a common character or norm.

Mesial Inclination: The tooth is tilted mesially i.e the crown is mesial to root.

Distal Inclination: The tooth is tilted distally i.e the crown is distal to the root.

Lingual Inclination: The tooth is abnormally tilted towards the tongue.

Labial/Buccal Inclination: The tooth is abnormally inclined towards the lips/cheeks.

Infra-Occlusion: The tooth is below the occlusal plane as compared to other teeth in the arch.

Supra-Occlusion: The tooth is above the occlusal plane as compared to other teeth in the arch.

Rotations: This term refers to tooth movements around the long axis of the tooth. Types as follows:

1)Mesiolingual/Distolabial: Mesial aspect of the tooth is lingually placed or the distal aspect of the crown is labially placed

2)Distolingual/Mesiolabial: Distal aspect of the tooth is lingually lingually inclined or the mesial aspect is labially placed.

3)Transposition: In this two teeth exchange places,eg-canine in place of lateral incisor.

This malocclusions are characterized by abnormal relationship between teeth or groups of teeth of one dental arch to that of the other arch. These malrelations can occur in all three planes of space, sagittal, vertical, transverse.

SAGITTAL PLANE MALOCCLUSIONS

Pre-normal Occlusion: Mandibular dental arch is placed more anteriorly

Post-normal Occlusion: Mandibular dental arch is placed more posteriorly

VERTICAL PLANE MALOCCLUSIONS

Deep Bite: Vertical overlap between maxillary and mandibular teeth is excess of the normal.

Open Bite: An overlap or gap exists between the maxillary and mandibular teeth when patient bites in centric occlusion. It can be anterior or posterior.

TRANSVERSE PLANE MALOCCLUSIONS

Due to constriction of arches or some other reason the relationship is disturbed i.e one or more maxillary teeth are placed palatal/lingual to mandibular teeth

Angle classified malocclusion into three broad categories.

CLASS I: Mandibular dental arch is in normal mesiodistal relation to maxillary arch, with the mesio-buccal cusp of maxillary first molar occluding in buccal groove of mandibular first permanent molar and mesiolingual cusp of maxillary first permanent molar occludes with the occlusal fossa of mandibularfirst permanent molar in centric occlusion.

CLASS II: Mandibular dental arch is in distal relation to maxillary arch. The mesiobuccal cusp of maxillary first permanent molar occludes in space between the mesiobuccal cusp of the mandibular first permanent molar and the distal aspect of the mandibular second pre-molar. Also the mesiolingual cusp of the maxillary first permanent molar occludes mesial to mesio-lingual cusp of mandibular first permanent molar.

Angle divided class II into two divisions i.e…

Class-II Division 1: Along with the class II relation there is labio-version of maxillary incisor.

Class-II Division 2: Along with the class II relation the maxillary incisors are near normal or slightly in linguoversion and the maxillary lateral incisors are tipped labially/mesially.

CLASS III: Mandibular dental arch is in mesialrelationship to the maxillary arch, with the mesiobuccal cusp of maxillary permanent first molar occluding in the interdental space between the distal aspect of the distal cusps of mandibular first molar and mesial aspect of the mesial cusps of mandibularsecond molar.

Psedo Class III: Not a true class III malocclusion but the presentation is similar. Here the mandible shifts anteriorly in the glenoid fossa due to premature contact of teeth or some other reason.

1) Angle presumed that 1st permanent molar as fixed points within the jaws, which is not so.

2) Angle depended exclusively on 1st molars. Hence the classification is not possible if the given tooth is missing or applied in deciduos dentition.

3) Malocclusions are only considered in anteroposteriorplane. Transverse and vertical planes are not considered.

4) Individual teeth malocclusion are not considered

5) Etiology of malocclusion has not been elaborated upon.

1) Frankfort horizontal(vertically)

2) Orbital plane(anteroposteriorly)

3) Raphe or median sagittal plane(transverse)

Frankfort Horizontal: F-H plane or eye-ear plane is the straight line through the margins of bony orbit directly under the pupil of the eye to upper margins of external auditory meatus.

When dental arch is closer to F-H plane Attractions

When dental arch is further away from F-H plane Abstractions

Orbital Plane: This plane is perpendicular to the eye-ear plane(Frankfort Horizontal Plane) directly under pupil of eye.

The teeth, one or both, dental arches are too far forward i.e. placed forward called Protraction.

The teeth, one or both dental arches are too far backward, i.e. placed posterior to the plane than normal is called Retraction.

Median Sagittal Plane: The median plane passes through these two points at right angles to frankfort horizontal plane.

A part or all of dental arch is contracted towards the median sagittal plane is called Contraction.

A part or all of dental arch is wider or placed at a distance which is more than normal is called Distraction.

A and P proposed a very comprehensive system of classification which divided malocclusions in all the three planes of space and gave an indication towards

the severity of malocclusion present. The classification is illustrated using the Venn symbolic logic diagram.

The classification considered five characteristics . They are:

CHARACTERISTIC 1- ALIGNMENT: It is assessed as when seen in occlusal view, they are classified as ideal/crowded/spaced.

CHARACTERISTIC 2- PROFILE: It can be Convex/straight or concave

CHARACTERISTIC 3- TRANSVERSE RELATIONSHIPS: Buccal and palatal cross bites are noted. Further subclassified as unilateral or bilateral.

CHARACTERISTIC 4- CLASS: Here the sagittalrelationship is assessed using Angle’s classification as Class I/Class II/Class III.

CHARACTERISTIC 5- OVERBITE: They are assessed in vertical plane. They are described as anterior open bite/posterior open bite/anterior deep bite/posterior collapsed bite.

It is considered as more simpler and more relevant than Angle’s classification. Adopted by British Standard Institute in 1983 and is based upon the relationship of lower incisor edges and the cingulum plateau of maxillary central incisor.

Class I: Mandibular incisor edges occlude with or lie immediately below the cingulum plateau of maxillary central incisors.

Class II: Mandibular incisor edges lie posterior to the cingulum plateau of maxillary central incisor.

Division 1: The maxillary central incisors are proclined or of average inclination with increased overjet.

Division 2: The maxillary central incisors are retro-clined; the overjet is normally minimum.

CLASS III: The mandibular incisor lie anterior to the cingulum plateau of upper central incisors, the overjetis reversed.

The Ackerman and Profitt classification conveys the maximum information regarding the characteristics of a malocclusion,yet it is not frequently used. The incisor classification is the simplest to use, yet not frequently used, Angle’s classifications with all its shortcomings, is still by far the most commonly used classification of malocclusion.