CLASSIFICATION OF MALOCCLUSION

Dr MUHAMMED RAHEESH

SENIOR LECTURER

DEPT OF ORTHODONTICS

CONTENTS

• Types of malocclusion
• Angle’s Classification

INTRODUCTION

• Malocclusion is a condition in which there is a departure from the normal relation of the teeth to other teeth in the same arch and /to teeth in the opposite arch.

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TYPES OF MALOCCLUSIONS

• INTRA ARCH MALOCCLUSION that include variations in individual tooth position and malocclusions affecting a group of teeth within arch.
• INTER ARCH MALOCCLUSION that comprise of malrelation of dental arches to one another upon skeletal bony bases,which may themselves be normally related.
• SKELETAL MALOCCLUSION that involve the underlying bony bases.

INTRA ARCH MALOCCLUSION

• A tooth can be abnormally related to its neibouring teeth. Such abnormal variations are called individual teeth malposition.
• It can be abnormal inclination of the teeth or abnormal displacements.
• Abnormal inclination involves the tilting of the crown, with the root being in normal position.
• Bodily displacement involves abnormal location of the crown as well as the root in the same position

• DISTAL INCLINATION;crown is tilted or inclined distally
• MESIAL INCLINATION;crown is tilted or inclined mesially
• LINGUAL INCLINATION;lingual or palatal tilting of the tooth.
• BUCCAL INCLINATION;labial or buccal tilting of the tooth.
• MESIAL DISPLACEMENT;refers to a tooth that is bodily moved in a mesial direction towards the midline

• DISTAL DISPLACEMENT ;Refers to a teeth that is bodily moved in a distal direction away from the midline.
• LINGUAL DISPLACEMENT;entire tooth is displaced in a lingual direction.
• BUCCAL DISPLACEMENT ;describes a condition where the tooth is displaced bodily in a labial or buccal direction.
• INFRAVERSION;refers to a tooth that has not erupted enough compared to other teeth in the arch.

• SUPRAVERSION; tooth that has erupted as compared to other teeth in the arch.
• ROTATION; refers to the tooth movements around its long axis.
• DISTOLINGUAL ROTATION; tooth that has 0moved around its long axis so that the distal aspect more lingually placed.
• MESIOLINGUAL ROTATION; tooth has rotated around its long axis so that the mesial aspect of the tooth is more lingually placed
• TRANSPOSITION; a condition where 2 teeth have exchanged places.

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INTER ARCH MALOCCLUSION

• Characterized by abnormal relationship between 2 teeth or group of teeth of one arch to the other arch.
• It can occur in the sagittal, vertical or in the transverse planes of space.

SAGITTAL PLANE MALOCCLUSION

• This includes condition where the upper and lower arches are abnormally related to each other in a sagittal plane.
• Pre normal occlusion; condition where the lower arch is more forwardly placed when the patient bites in centric occlusion
• Post-normal occlusion; condition where the lower arch is more distally placed when te patient bites in centric occlusion

VERTICAL PLANE MALOCCLUSION

• Include deep bite and open bite where an abnormal vertical relation exist between the teeth of the upper and lower arch.
• Deep bite/increased overbite;condition where there is excessive vertical overlap between the upper and lower anteriors
• Open bite;this is a condition where there is no vertical overlap between the upper and lower teeth.

TRANSVERSE PLANE MALOCCLUSION

• Includes various types of crossbites
• Crossbite refers to the abnormal transverse relationship between the upper and lower arches

SKELETAL MALOCCLUSION

• Malocclusion caused due to abnormalities in the maxilla or mandible
• The defects can be in size, position,or relationship between the jaws
• It can also occur in 3 planes of space namely sagittal, vertical, and transverse planes
• Sagittal; prognathism,retrognathism

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• ANGLE’S SYSTEM OF CLASSIFICATION

• The first useful orthodontic classification, still important now, was Angle’s classification of malocclusion into Classes I,II,III .
• The basis of the Angle classification was the relationship of the first molar teeth and the alignment of the teeth relative to the line of occlusion.
• Angle’s classification thus created 4 groups

• Normal occlusion;normal[class I] molar relationship ,teeth on the line of occlusion.
• Class I malocclusion;normal[class I] molar relationship,teeth crowded,rotated,etc.
• Class II malocclusion;lower molar distal to upper molar,relationship of other teeth to line of occlusion.
• Class III malocclusion;lower molar mesial to upper molar,relationship of other teeth to line of occlusion not specified

• Angle’s concept of normal occlusion is based on

1.line of occlusion

2.key of occlusion

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KEY OF OCCLUSION

• Angle considered maxillary first permenant molar as the key of occlusion.
• He said maxillary first molar is the most constant in its position.
• Angle related maxillary first molar to key ridge position.
• The mesiobuccal cusp of upper first molar rests in the mesiobuccal groove of the mandibular first molar in normal occlusion called class I molar relation

LINE OF OCCLUSION

• There are 2 lines of occlusion
• 1.maxillary
• 2.mandibular
• Maxillary;smooth curve passing through the central fossa of upper molars and along the cingulum of upper canine and incisors.
• Mandibular;runs along the buccal cusp of posteriors and incisal edges of the anteriors

Angle’s Class I

• Characterized by the presence of a normal inter-arch molar relation.
• Mesio-buccal cusp of the maxillary first permanent molar occludes in the buccal groove of mandibular first permanent molar.
• Dental irregularities such as crowding, spacing, rotation ,missing tooth etc.
• Exhibit normal skeletal relation ,also show normal muscle function
• Another malocclusion under this is the bimaxillary protrusion

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Angle’s class II

• 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
• Subdivided into 2 divisions

Class II Division I

Class II Division II

Class II Division 1

• Characterized by proclined upper incisors with a resultant increase in overjet.
• A deep incisor overbite can occur in the anterior region,presence of abnormal muscle activity
• The upper lip usually hypotonic,short and fails to form a lip seal.
• Lower lip cushions the palatal aspect of the upper teeth called as lip trap.
• V shaped upper arch,hyper active muscle activity

Class II Division 2

• Exhibits a Class II molar relationship.
• Classic feature is the presence of lingually inclined upper central incisor and labially tipped upper lateral incisor.
• Exhibits a deep anterior over bite
• Lingually inclined upper centrals give the arch a squarish appearance
• Mandibular labial gingival tissue is often traumatized .

• Exhibits normal perioral muscle activity
• An abnormal backward path of closure may also be present due to the excessively tipped central incisor
• Class II subdivision;when a Class II molar relation exists on one side and a Class I molar relation on the other

Class III 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 molar
• Classified into 2

True class III

Pseudo class III

TRUE CLASS III

• Skeletal class III malocclusion of genetic origin that can occur due to following causes;

a.excessively large mandible

b.forwardly placed mandible

c.smaller than normal maxilla

d.retropositioned maxilla

e.combination of the above causes

• Lower incisor tend to be lingually inclined
• The patient can present with a normal overjet,an edge to edge incisor relation or an anterior crossbite
• 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

• Produced by forward movement of mandible during jaw closure.
• Also called as postural or habitual class III malocclusion
• Causes are
• presence of occlusal prematurities
• premature loss of deciduous posteriors
• a child with enlarged adenoids

Class III subdivision

• Characterized by a Class III molar relation on one side and a Class I relation on other side

DRAWBACKS OF ANGLE’S CLASSIFICATION

• Angle considered malocclusion only in the antero posterior plane; did not consider in the transverse and vertical planes .
• Angle considered first permanent molar as fixed point in the skull. But this is not found to be so.
• The classification cannot be applied if the first permanent molars are extracted or missing

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• The classification cannot be applied to the deciduous dentition.
• The classification does not differentiate between skeletal and dental malocclusion
• The classification does not highlight the etiolgy of malocclusion
• Individual tooth malposition have not been considered by Angle

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POSSIBLE QUESTIONS

• Describe Angle’s Classification
• What are the drawbacks of Angle’s Classification.