The Classification of Malocclusion has been done by many and is given in detail below:
Angle’s System of classification of malocclusion
Edward Angle introduced a system of classifying malocclusion in the year 1899. Angle’s classification is still in use after almost 100 years of its introduction due to its simplicity of application.
Basis for Angle’s classification of malocclusion
The Angle’s classification of malocclusion is based on the following criteria:
a. Angle’s classification was based on the mesio-distal relation of the teeth, dental arches and the jaws.
b. According to Angle, the maxillary first permanent molar is the key to occlusion. He considered these teeth as fixed anatomical points within the jaws.
c. Based on the relation of the lower first permanent molar to the upper first permanent molar, he classified malocclusion into three main classes designated by the Roman numerals I, II and III.
Based on the above mentioned principles, Angle’s classification of malocclusion was done into the following broad categories.
Angle’s Class I classification of malocclusion
Angle’s Class I classification of malocclusion is characterized by the presence of a normal inter-arch molar relation. The mesio-buccal cusp of the maxillary first permanent molar occludes in the buccal groove of mandibular first permanent molar. The patient may exhibit dental irregularities such as crowding, spacing, rotations, missing tooth, etc.
These patients exhibit normal skeletal relation and also show normal muscle function. Another malocclusion that is most often categorized under Class I is bi-maxillary protrusion where the patient exhibits a normal Class I molar relationship but the dentition of both the upper and lower arches are forwardly placed in relation to the facial profile.
Angle’s Class II classification of malocclusion
This group is characterized by a Class II molar relation where the disto-buccal cusp of the upper first permanent molar occludes in the buccal groove of the lower first permanent molar. Angle has sub-classified Class II malocclusion into two divisions:
Class II, Division 1 classification of malocclusion
The Class II, Division 1 classification of malocclusion is characterized by proclined upper incisors with a resultant increase in over jet. A deep incisor overbite can occur in the anterior region. A characteristic feature of this malocclusion is the presence of abnormal muscle activity. The upper lip is usually hypotonic, short and fails to form a lip seal.
The lower lip cushions the palatal aspect of the upper teeth, a feature typical of a Class II classification of malocclusion, Division 1 referred to as ‘lip trap’. The tongue occupies a lower posture thereby failing to counteract the buccinator activity. The unrestrained buccinator activity results in narrowing of the upper arch at the premolar and canine regions thereby producing a V-shaped upper arch.
Another muscle aberration is a hyper-active mentalis activity. The muscle imbalance is produced by a hyper-active buccinator and mentalis and an altered tongue position that accentuates the narrowing of the upper dental arch.
Class II, Division 2 classification of malocclusion
As in Class II, Division 1 classification of malocclusion, the Division 2 also exhibits a Class II molar relationship. The classic feature of this malocclusion is the presence of lingually inclined upper central incisors and labially tipped upper lateral incisors overlapping the central incisors. Variations of this forms are lingually inclined central incisor and lateral incisors with canine labially tipped. The patients exhibits a deep anterior overbite.
The lingually inclined upper centrals gives the arch a squarish appearance, unlike the narrow V-shaped arch seen in Division 1 classification of malocclusion. The mandibular labial gingival tissue is often traumatized by the excessively tipped upper central incisors. The patients exhibit normal perioral muscle activity. An abnormal backward path of closure may also be present due to the excessively tipped central incisors.
Class II, Subdivision classification of malocclusion
When a Class II molar relation exists on one side and a Class I relation on the other, it is referred to as Class II, Subdivision. Based on whether it is a Division 1 or Division 2 it can be called Class II, Division 1, Subdivision or Class II, Division 2, Subdivision.
Class III malocclusion classification of malocclusion
This malocclusion exhibits a Class III molar relation with the mesio-buccal cusp of the maxillary first permanent molar occluding in the interdental space between the mandibular first and second molars. Class III classification of malocclusion can be classified into true Class III not pseudo Class III.
True Class III classification of malocclusion
This is a skeletal ClassIII classification of malocclusion of genetic origin that can occur due to the following causes:
a. Excessively large mandible
b. Forwardly placed mandible
c. Smaller than normal maxilla.
d. Retropositioned maxilla
e. Combination of the above causes
The lower incisors tend to be lingually inclined. The patient can present with a normal overjet, an edge to edge incisor relation or an anterior cross bite. The space available for the tongue is usually more. Thus the tongue occupies a lower position, resulting in a narrow upper arch.
Pseudo Class III classification of malocclusion
This type of malocclusion is produced by a forward movement of the mandible during jaw closure thus it is also called ‘postural’ or’habitual’ Class III classification of malocclusion. The following are some of the causes of pseudo Class III malocclusion:
a. Presence of occlusal prematurities may deflect the mandible forward.
b. In case of premature loss of deciduous posteriors, the child tends to move the mandible forward to establish contact in anterior region.
c. A child with enlarged adenoids tends to move the mandible forward in an attempt to prevent the tongue from contacting the adenoids.
Class III Subdivision classification of malocclusion
This is a condition characterized by a Class III molar relation on one side and a Class I relation on the other side.
Drawbacks of Angle’s classification of malocclusion
Although Angle’s classification of malocclusion has been used for almost a hundred years now, it still has a number of drawbacks that include:
a. Angle considered malocclusion on the antero-posterior plane. He did not consider malocclusions in the transverse and vertical planes.
b. Angle considered the first permanent molars as fixed points in the skull. But is not found to be so.
c. The classification cannot be applied if the first permanent molars are extracted or missing.
d. The classification cannot be applied to the deciduous dentition.
e. The classification does not differentiate between skeletal and dental malocclusions.
f. The classification does not highlight the etiology of the malocclusion.
g. Individual tooth malpositions have not been considered by Angle.
Dewey’s Modification of Angle’s classification of malocclusion
Dewey proposed a modification of the Angle’s classification of malocclusion. He divided Angle’s Class I into five types and Angle’s Class III into three types.
Class I modifications of Dewey classification of malocclusion
Type 1: Class I malocclusion with bunched or crowded anterior teeth.
Type 2 : Class I with protrusive maxillary incisors.
Type 3: Class I malocclusion with anterior crossbite.
Type 4: Class I molar relation with posterior crossbite.
Type 5: The permanent molar has drifted mesially due to early extraction of second deciduous molar or second premolar.
Class III modifications of Dewey:
Type 1: The upper and lower dental arches when viewed separately are in normal alignment. But when the arches are made to occlude the patient shows an edge to edge incisor alignment, suggestive of a forwardly moved mandibular dental arch.
Type 2: The mandibur incisors are crowded and are in lingual relation to the maxillary incisors.
Type 3: The maxillary incisors are crowded and are in cross bite in relation to the mandibular anteriors.
Lischer’s Modifications of Angle’s classification of malocclusion
Lischer substituted the term Class I, II and III given by Angle with the terms neutrocclusion, distocclusion and mesioclusion. In addition to these, he added a few more terms which designated certain other malocciusions.
NeutroccIusion : Synonymous with Angle’s Class I malocclusion.
Distocclusn: Synonymous with Angle’s Class II malocclusion.
Mesioclusion: Synonymous with Angle’s Class III malocclusion.
Buccocclusion: Buccal placement of a tooth or a group of teeth.
Linguocclusion: Lingual placement of a tooth or a group of teeth.
Supraocclusion: When a tooth or group of teeth have erupted beyond normal level.
Infraocclusion: When a tooth or group of teeth have not erupted to normal level.
Mesioversion: Mesial to the normal position.
Distoversion: Distal to the normal position.
Transversion:Transposition of two teeth.
Axiversion: Abnormal axial inclination of a tooth.
Torsiversion: Rotation of a tooth around its long axis.
Simon’s classification of malocclusion
Malocclusion can occur in antero-posterior, tranverse and in the vertical planes. Simons had put forward a craniometric classification of malocclusion that related the dental arches in all these three planes.
Simon’s system of classification of malocclusion made use of three anthropometric planes, i.e, the frankfort horizontal plane, the orbital plane and the mid-sagittal plane. The classification of malocclusion was based abnormal deviations of the dental arches from their normal position in relation to these three planes.
Frankfort horizontal plane
This is a plane that connects the upper margin of the external auditory meatus to the infra-orbital margin. This plane is used to classify malocciusions in a vertical plane. Two terms are used to describe any abnormal relation of the teeth to this plane. When the dental arch or part of it is closer than normal to the Frankfort plane, it is called attraction. When the dental arch or part of it is farther away from the Frankfort horizontal plane, it is called abstraction.
This plane is perpendicular to the Frankfort horizontal plane, dropped down from the bony orbital margin directly under the pupil of the eye. According to Simon, this plane should pass through the distal third of the upper canine. This plane is used to describe malocculsion in a sagittal or antero-posterior direction. When the dental arch or part of it is farther from the orbital plane, it is called protraction. When the arch or part of it is closer or more posteriorly placed in relation to this plane, it is called retraction.
The mid-sagittal plane is used to describe malocclusion in the tranverse direction. When a part or whole of the arch is away from the mid-sagittal plane it is called distraction. When the arch of part of it is closer to the mid-sagittal plane it is called contraction.
Bennet’s classification of malocclusion
Norman Bennet classified malocclusion based on its etiology.
Class I – Abnormal position of one or more teeth due to local causes.
Class II – Abnormal formation of a part of or whole of either arch due to developmental defects of bone.
Class III – Abnormal relationship between upper and lower arches, and between either arch and facial contour and correlated abnormal formation of either arch.
Ackerman-profit system of classification of malocclusion
Ackerman and profitt in 1960 proposed a diagrammatic classification of malocclusion to overcome the limitations of the Angle’s classification of malocclusion. Salient features of the classficiation include:
a. Tranverse as well as vertical discrepancies can be considered in addition to antero-posterior malrelations.
b. Crowding and arch asymmetry can be evaluated.
c. Incisor protrusion is taken into account.
This system of classification of malocclusion is based on the Venn symbolic diagram that identifies five major characteristics to be considered and described in the classification.
Step 1 (Alignment)
The first step involves assessment of the alignment and symmetry of the dental arch. It is classified as ideal/crowded/spaced.
Step 2 (Profile)
It involves the consideration of the profile. The profile is described as convex/straight/concave. The facial divergence is also considered, i.e, anterior or posterior divergence.
Step 3 (Type)
The transverse skeletal and dental relationships is evaluated. Buccal and palatal cross bites if any are noted. The cross bite is further sub-classified as unilateral or bilateral. In addition, differentiation is made between skeletal and dental cross bite.
Step 4 (Class)
This involves the assessment of the sagittal relationships. It is referred as Angle’s Class I/Class II/Class II classification of malocclusion. Differentiation is made between skeletal and dental malocclusion.
Step 5 (Bite depth)
Malocclusions in the vertical plane are noted. They are described as anterior or posterior open bite, anterior deep bite or posterior collapsed bite. A mention is made whether the malocclusion is skeletal or dental.