Classification of Malocclusion
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INTRODUCTION ď Ž Definition:
Malocclusion is defined as any deviation from normal occlusion of teeth. The teeth are in abnormal position in relationship to the basalbone of the alveolar process, to the adjacent teeth and/or opposing teeth.
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INTRODUCTION The alignment and occlusion of the dentition are
extremely important in various oral functions. But tooth positions are determined not by chance but by numerous factors such as arch width and tooth size. Any alteration in such factors can give rise to malocclusion. As orthodontics is a “science of infinite variations”(by jackson), it becomes necessary to group the variety of malocclusions into various groups for our better understanding. www.indiandentalacademy.com
INTRODUCTION ď Ž Classification involves the grouping together
of various malocclusion into simpler or smaller groups. In order to have a system of classification, standards should be set up that represents normalcy. The deviations from the accepted norms should also be grouped into various smaller divisions or categories.
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Advantages 1. classification helps in diagnosis and
treatment planning. 2. classification helps in visualizing and understanding the problem associated with that malocclusion. 3. classification helps in communicating the problem. 4. comparison of various malocclusion becomes easy. www.indiandentalacademy.com
TYPES OF MALOCCLUSIONS Malocclusion can be broadly divided into 1.Individual teeth malposition or intra-arch
malocclusion. 2.Malrelation of dental arches to one another upon bony bases which may themselves be normally related. 3.Skeletal malocclusions which involve the underlying bony bases.
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Individual Tooth Malpositions ď Ž These are malposition of individual teeth in
respect to adjacent teeth with in the same dental arch. Hence are called intra-arch malocclusions. Some of the commonly seen individual teeth malpositions are:
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MESIAL INCLINATION OR TIPPING ď Ž In this condition the tooth is tilted mesially, i.e.
the crown is mesial to the root.
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DISTAL INCLINATION OR TIPPING ď Ž The tooth is tilted distally, i.e. the crown is
distal to the root.
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LINGUAL INCLINATION OR TIPPING ď Ž The tooth is abnormally tilted towards the
palate {for the palate in the maxillary arch}.
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LABIAL/BUCCAL INCLINATION OR TIPPING ď Ž The tooth is abnormally inclined towards the
lips/cheeks.
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INFRA-OCCLUSION ď Ž The tooth is below the occlusion plane as
compared to other teeth in the arch.
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SUPRAOCCLUSION ď Ž The tooth is above the occlusal plane as
compared to other teeth in the arch.
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ROTATIONS This term refers to tooth movements around
the long axis of the tooth. Mesiolingual or Distolabial. Distolingual or mesiolabial.
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MESIOLINGUAL OR DISTOLABIAL ROTATION ď Ž The mesial aspect of the tooth is inclined
lingually or in other words, the distal aspect of crown is labially placed as compared to its mesial aspect.
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DISTOLINGUAL OR MESIOLABIAL ROTATIONS ď Ž The distal aspect of the tooth is inclined
lingually or the mesial aspect of the crown is labially placed as compared to its distal aspect.
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TRANSPOSITION ď Ž This term is used in case where two teeth
exchange places, e.g. a canine in place of the lateral incisor.
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MALRELATIONS OF DENTAL ARCHES яБо SAGITTAL PLANE MALOCCLUSION
TWO TYPES1.PRE NORMAL OCCLUSION 2.POST NORMAL OCCLUSION
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PRE-NORMAL OCCLUSION ď Ž Where the mandibular dental arch is placed
more anteriorly when the teeth meet in centric occlusion.
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POST-NORMAL OCCLUSION ď Ž Where the mandibular dental arch is placed
more distally when the teeth meet in centric occlusion.
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VERTICAL PLANE MALOCCLUSION ď Ž TWO TYPES-
1. DEEP BITE-Here the vertical overlap between the maxillary and mandibular teeth is in excess.
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2.OPEN BITE ď Ž No overlap or a gap exists between the
maxillary and mandibular teeth when patient bites in centric occlusion, can exist in the anterior or posterior region.
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TRANSVERSE PLANE MALOCCLUSIONS ď Ž The transverse plane inter-arch malocclusion
includes various types of cross bites. The term cross bite refers to abnormal transverse relationship between upper and lower arches.
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SKELETAL MALOCCLUSION ď Ž These malocclusion are caused due to the
defect in the underlying skeletal structure itself. The defect can be in size, position or relationship between the jaw bones.
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OCCLUSAL RELATIONSHIP OF POSTERIOR TEETH In 1899, Edward Angle classified
malocclusion based on the mesial-distal relation of the teeth, dental arches and jaws. He considered the maxillary first permanent molar as a fixed anatomical point in the jaws and the key to occlusion. Angle’s classified malocclusion into three broad categories.
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CLASS-I MALOCCLUSION 1.The mesiobuccal cusp of the mandibular
first molar occludes in the embrasure area between the maxillary second premolar and first molar. 2.The mesiobuccal cusp of the maxillary first molar is aligned directly over the buccal groove of the mandibular first molar. 3.The ML cusp of the maxillary first molar is situated in the central fossa area of mandibular first molar. www.indiandentalacademy.com
ď Ž In this relationship each mandibular tooth
occludes with its counterpart and the adjacent mesial tooth.
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CLASS-II MALOCCLUSION 1.The mesiobuccal cusp of the mandibular
first molar occludes in the central fossa area of the maxillary first molar. 2.The mesiobuccal cusp of the mandibular first molar is aligned with the buccal groove of the maxillary first molar. 3.The DL cusp of the maxillary first molar occludes in the central fossa area of the mandibular first molar. www.indiandentalacademy.com
ď Ž When compared with class-I, each occlusal
contact pair is situated to the distal approximately the MD width of premolar.
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CLASS II-DIVISON I ď Ž Along with the molar relation as seen in
typical class II malocclusion the maxillary incisor teeth in are in labio-version.
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CLASS II DIVISON 2 ď Ž Along with typical class II molar relationship,
the maxillary incisor are near normal anteroposteriorly or slightly in linguoversion where as the maxillary lateral incisor are tipped labially.
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CLASS II-SUBDIVISION ď Ž When the class II molar relationship occurs
on one side of the dental arch only, the malocclusion is referred to as a subdivision of its division.
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CLASS-III MALOCCLUSION ď Ž The distobuccal cusp of the mandibular first
molar is situated in the embrasure between the maxillary second premolar and first molar. ď Ž The MB cusp of the maxillary first molar is situated over the embrasure between the mandibular first and second molar.
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ď Ž The ML cusp of the maxillary first molar is
situated in the mesial pit of the mandibular second molar.
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PSEUDO CLASS III MALOCCLUSION ď Ž This is not a true class III malocclusion but
the presentation is similar. Here the mandible shifts anteriorly in the glenoid fossa due to a premature contact of the teeth or some other reason when jaws are brought together in centric occlusion.
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DRAWBACK OF ANGLES CLASSIFICATION Angle presumed the first molars as fixed
points within the jaws, which definitely is not so. The classification is not possible , if the first molars are missing. Classification is not applicable in deciduous dentition. Individual tooth malocclusion are not considered. www.indiandentalacademy.com
Malocclusion are considered only in the
anteroposterior plane. There is no differentiation between skeletal and dental malocclusion. Etiology of the malocclusions has not been elaborated upon.
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INCISOR CLASSIFICATION ď Ž It was adopted by the British standards’
institute in 1983 and is based upon the relationship of the lower incisor edges and the cingulum plateau of the maxillary central incisors.
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VARIATIONS IN ANTERIOR TOOTH RELATIONSHIP
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VARIATIONS IN ANTERIOR TOOTH RELATIONSHIPS.
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CANINE RELATIONSHIP CLASS I RELATION: Mesial incline of the
upper canine overlaps the distal incline of the lower canine. CLASS II RELATION: In this canine
relationship upper canine is placed forward , i.e. distal incline of upper canine contacts the mesial incline of lower canine.
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ď Ž CLASS III RELATION: The lower canine is
placed forward to the upper canine and there is no overlapping.
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