CLASSIFICATION OF MAL OCCLUSION
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Angle's classification system categorizes malocclusions based on the mesial-distal relationship of the maxillary and mandibular first molars. It defines three main classes: Class I (normal), Class II (distal), and Class III (mesial). While widely used, it has limitations as it only considers the anteroposterior plane and requires intact first molars. Several alternative classifications were proposed to address these limitations, including those by Lischer, Dewey, Bennett, and Simon, which incorporate additional factors like etiology, individual tooth positions, and skeletal relationships.
CLASSIFICATION OF MAL OCCLUSION
- 1. Introduction Normalityis the basis ofclassification in orthodontics.It rests on what is known as biologic continuity, i.e., the mostfrequentlyfound relationship ofthe teeth and of the bones of the face in relation to each other and to the skull as a whole.Malocclusion is any perversion of normal occlusion ofthe teeth. It is a condition where there is departure from the normal relation ofthe teeth to other teeth in the same arch and to the teeth in the opposing arch. INTRODUCTION: INTRODUCTION In order to acquire a better understanding ofthe many deviations from normal occlusion and to assistin diagnosis and treatmentplanning,itbecomes necessaryto group the varieties of malocclusion into order. This is difficult as occlusal anomalies are manyand varied. Orthodontics has been described,admirably,as a ‘Science of Infinite Variations’. DEFINITION : DEFINITION Classification is a process ofanalyzing cases ofmalocclusion for the purpose ofsegregating them into a small number ofgroups,which groups are characterized by certain specific and fundamental variations from normal occlusion ofthe teeth. OBJECTIVES: OBJECTIVES Classification is an essential communication tool between dental school professor and student, between practitioners,and between practitioner and insurance companyor governmentbureaucracy. It is essential that everyone "speak the same language."Classification aids in the diagnosis and treatmentplanning of malocclusions byorienting the clinician to the type and the magnitude ofthe problems and possible mechanical solutions to the problems. OBJECTIVES Segregation ofthe countless number ofcases of tooth malposition into a comparativelylow number of groups,each group containing onlysuch cases as are characterized by a common factor or factors of fundamental significance.Ease ofreference i.e. giving name to a group of symptoms making together a s ingle problem Comparison ofcases with other cases having same problem GENERAL CLASSIFICATION: Malocclusion can be broadly divided into- Individual tooth malposition or Intra arch malocclusion Maxillo-mandibular malocclusions or Inter arch malocclusion GENERAL CLASSIFICATION: Individual tooth malposition or Intra arch malocclusion Atooth can be abnormallyrelated to its neighboring teeth, such abnormal variations are called individual tooth malpositions or intra arch malpositions.Some ofthe commonly seen individual tooth malpositions are Distal inclination or distal tipping Mesial inclination or mesial tipping Lingual inclination or lingual tipping Buccal inclination or buccal tipping
- 2. Individual tooth malposition or Intra arch malocclusion Mesial displacementDistal displacementLingual displacement Buccal displacementInfraversion or infraocclusion Supraversion or supra occlusion Disto lingual or mesio buccal rotation Mesio lingual or disto buccal rotation Transposition MESIAL INCLINATION DISTAL INCLINATION LINGUAL AND LABIAL INCLINATION MESIAL DISPLACEMENT DISTAL DISPLACEMENT INFRAVERSION SUPRAVERSION LINGUAL AND LABIAL DISPLACEMENT TORSIVERSION TRANSPOSITION Inter arch malocclusions These malocclusions are characterized by abnormal relationships between two teeth or groups ofteeth of one arch to the other arch. These inter arch malocclusion can occur in Sagital plane Vertical plane Transverse plane Sagital plane malocclusions Pre-normal occlusion- refers to a condition where the lower archis more forwardly placed when the patient bites in centric occlusion. Post-normal occlusion- a condition where the lower arch is more distally placed when the patient bites in centric occlusion. Vertical plane malocclusions Deep bite or increased over bite : this refers to a condition where there is an excessive vertical overlap between upper and lower anterior teeth. Open bite : is a condition where there is no vertical overlap between upper and lower teeth . Thus a space existbetween the upper and lower teeth when the patient bites in centric occlusion.Open bite can be in anterior or posterior region . Transverse plane malocclusions Cross bite – refers to a condition in which mandibular teeth overlap their maxillary antagonists.Cross bite can be anterior or posterior Buccal Non occlusion – refers to a condition in which maxillary posteriors are completelybuccallyplaced in relation to mandibular antagonists without occluding Palatal Non occlusion – refers to a condition in which maxillary posteriors are completelypalatallyplaced in relation to mandibular antagonists withoutoccluding ANGLE’S CLASSIFICATION: ANGLE’S CLASSIFICATION Angle believed that since biologic entities as well as inanimate elements can be arranged into well-defined classes,the same held also ofthe occlusion ofthe teeth and the shape ofthe face. Angle based his classification ofmalocclusion on the normal mesiodistal relations ofthe mesiobuccal cusps ofthe upper first molars in relation to the mandibular firstmolars. Basis for Angle’s classification Mostindicative irregularityof teeth found in antero-posterior relationship ofthe teeth and the jaws.There is a normal mesio distal or antero-posterior position for the body of the mandible with its superimposed mandibular dental arch to occupy in the anatomyof the skull.The maxillary dental arch being built upon a base that is a fixed section ofthe skull anatomy,is more or less stable in its relationship to variou s landmarks on the head and consequentlythe first molar teeth in this arch may be quite safelyselected as a key tooth from which to judge the relationship ofmandibular dental arch and intern to the body of mandible upon which itis located Basis for Angle’s classification Ifthere is shifting of maxillarymolars in their relationship to the skull anatomy,this variation can be detected by changes in the axial inclination ofteeth in the maxillaryarch. The axial change is especiallymanifested bycanine teeth. Curvature and line of occlusion is unique to each individual . Angle used the Roman numerals I,II and III to designate the three main classes ofmesiodistal arch relationship viz., Class Ior normal,Class IIor distal and Class IIIor mesial relationship ofthe cusps ofthe mandibular firstmolars to
- 3. the maxillary firstmolars.He employed the Arabic numerals 1 and 2 to denote divisions ofthe classifications. Unilateral deviations he termed subdivisions. ANGLE’S CLASSIFICATION Angle classified malocclusion as follows Class IClass IIDivision 1 Division II Subdivision Class IIISubdivision ANGLE’S CLASSIFICATION Class I Malocclusion The mandibular dental arch and the body of the mandible are in normal relation to the maxillaryarch indicated by the fact that mesiobuccal cusp ofthe maxillaryfirst permanentmolar occludes in the buccal groove of the mandibular permanentfirstmolar and the mesiolingual cusp of the maxillary firstmolar occludes with the occlusal fossa ofthe mandibular first permanentmolar when the jaws are in centric occlusion ANGLE’S CLASSIFICATION Class II Malocclusion The mandibular dental arch and the body of the mandible are in distal relation to the maxillary arch by half the width of the maxillaryfirst permanentmolar or mesioodistal width ofa premolar indicated bythe fact that mesiobuccal cusp ofthe maxillary firstpermanentmolar occludes in the space between the mesiobuccal cusp ofthe mandibular permanentfirstmolar and the buccal cusp of the second premolar. ANGLE’S CLASSIFICATION Class II Malocclusion The mesiolingual cusp ofthe maxillaryfirst molar occludes mesial to the mesiolingual cusp ofthe mandibular firstpermanentmolar when the jaws are in centric occlusion . ANGLE’S CLASSIFICATION Class II Malocclusion Division I A class II malocclusion in which maxilary incisors are in labioversion Subdivision Aclass II division I malocclusion occuring on onlyone side ANGLE’S CLASSIFICATION Class II Malocclusion Division II A class II malocclusion in which maxilary incisors are notin labioversion rather they are retroclined with laterals overlapping centrals or canines overlapping laterals Subdivision A class IIdivision I malocclusion occuring on onlyone side ANGLE’S CLASSIFICATION Class III Malocclusion The mandibular dental arch and the body of the mandible are in mesial relationship to the maxillaryarch indicated by the fact that mesiobuccal cusp ofthe maxillary firstpermanentmolar occludes in the interdental space between the distal aspectofthe distal cusp ofthe mandibular firstpermanentmolar and the mesial aspectofthe mesial cusp of the second permanentmolar : ANGLE’S CLASSIFICATION Class III Malocclusion Subdivision A classIII malocclusioninwhichmalocclusionisonlyunilaterally ANGLE’S CLASSIFICATION Pseudo-Class III Malocclusion In this condition the mandible is protruded a little during the final stages ofclosure in order to avoid a premature contactof incisors or canines This is mostlikelyto arise in cases where the relationship ofthe incisors is edge-to-edge,and maybe caused by a mildly prenormal relationship of the dental bases Such pseudo – or postural Class IIIcases maytend, if left untreated,to become established bya further developmentof the whole occlusion in Class IIIrelation. Features True Class III Pseudo Class III 1 Profile Concave Straightto concave 2 Etiology Hereditary Habitual/developmental 3 Premature contacts AbsentPresent4 Path of closure Forward Deviated 5 Gonial angle Increased/decreased Normal 6 Retrusion ofmandible further Notpossible Possible 7 Treatment Orthopedic or surgical Elimination ofprematurities,replacementoflostposterior teeth 8 Left untreated No further changes Becomes established into true class III Differences between true and pseudo class IIImalocclusion
- 4. ANGLE’S CLASSIFICATION Drawbacks of Angle’s Classification The Angle classification was readilyaccepted by the dental profession,since itbroughtorder out of what previouslyhad been confusion regarding dental relationships.Itwas recognized almostimmediately,however,that there were deficiencies in the Angle system. Angle considered malocclusion onlyin antero-posterior plane Angle considered maxillaryfirstpermanentmolar as a fixed pointbut it was not found so The classification cannotbe applied iffirstpermanentmolars are missing or extracted The classification cannotbe applied in the deciduous dentition The classification does notdifferentiates between skeletal and dental malocclusions The classification does not highlightthe etiology of the malocclusion Individual tooth malpositions have notbeen considered in the classification LISCHER’S CLASSIFICATION: Lischer introduced the following terms which are widelyused to describe the varieties of malocclusion.He substituted the term Class I, Class II,Class III given by angle with the terms Neurtro-occlusion,Disto-occlusion and Mesio- occlusion . Neutro-occlusion:Normal relation ofdental arches.It is synonymous with Angle’s Class Imalocclusion.Disto - occlusion:Synonymous with Angle’s Class II, used to describe all cases ofpost-normal occlusion.Mesio-occlusion: Synonymous with Angle’s Class III and describes all cases ofprenormal occlusion. He gave the suffix “version” to describe the wrong position ofindividual teeth as follows:Linguo version —Lingual placementLabio version—Labial placementMesio version—Mesial placementDisto version—Distal placementInfra version—Intrusion ofteeth Supra version—Extrusion ofteeth Torsiversion—Rotation Perversion—Impacted tooth Dewey’s Modification of Angle’s Classification: Dewey proposed a modification ofthe Angle’s classification ofmalocclusion.He divided the Angle’s class Iinto five types and Angle’s Class III into three types. There were no modifications for Class II. He considered the same molar relationship as in Angle’s classification Dewey’s Modification of Angle’s Classification Modification of Angle’s Class I Type 1 . Bunched or crowded maxillaryanterior teeth. The canines maybe in labioversion or infraversion.All other versions ofindividual teeth may be presentType 2. Maxillary incisors in labioversion Type 3 . The maxillary incisor teeth are in linguoversion to the mandibular incisors Type 4 . The molars,occasionallyalso premolars are in linuoversion or labiobversion butcanines and incisors are in normal relation Type 5 . The molars are in mesioversion due to shifting following loss ofteeth anterior to molars Dewey’s Modification of Angle’s Classification Modification of Angle’s Class III Type 1 . The dental arches are well formed and the teeth are in normal alignmentwhen viewed individuallybut there is edge-to-edge bite in anterior region Type 2. The mandibular incisors are crowded and in lingual relation to the maxillary incisors Type 3 . The maxillary arch is underdeveloped.The maxillaryincisor are crowded.The mandibular arch is well developed and the mandibular teeth are in normal aligment BENNET’S CLASSIFICATION: Norman Bennettintroduced a classification ofabnormalities ofocclusion which was based on their etiology. Briefly the classification is as follows:Class I - Abnormal position ofone or more teeth due to local causes.Class II - Abnormal formation ofa part or whole of either arch due to developmental defects ofbone. Class III- Abnormal relationship between upper and lower arches,and between either arch and facial contour and correlated abnormal formation of either arch.
- 5. SIMON’S CLASSIFICATION: Since growth of the face and jaws occurs in the three planes ofspace-height,width and depth, abnormalities also occur in any one or more of the foregoing planes.Simon’s craniometric classification relates the denture to the face and cranium in the three planes ofspace,(1) The Frankfort horizontal (2) The Orbital plane and (3) The raphe or median sagittal plane. SIMON’S CLASSIFICATIONTheFrankforthorizontal plane The Frankfort horizontal plane or the eye- ear plane is determined bydrawing a straightline through the margin ofthe bony orbitdirectly under the pupil of the eye, to the upper margin of the auditory meatus (the notch above the tragus of the ear). This plane is used to determine deviations in the heightof the dental arches and teeth in relation to the face and cranium. SIMON’S CLASSIFICATIONTheOrbital plane The orbital plane is a perpendicular atrightangles to the eye- ear plane at the margin ofthe bony orbitdirectly under the pupil of the eye. This plane is used to determine sagittal deviations of the dental arches and the axial inclination ofthe teeth to the face and the cranium. SIMON’S CLASSIFICATIONTheRapheorMedianSagittal plane The Raphe or Median Sagittal plane is determined bypoints approximately1.5 cm apart on the median raphe ofthe palate.The raphe median plane passes through these two points atright angles to the Frankfort horizontal plane.This plane is used to determ ine the deviations in the general form and width of the dental arches and the axial inclination ofthe teeth in relation to the midline ofthe palate and the head The Law of the Canine In normal arch relationship,according to Simon,the orbital plane passes through the distal axial aspectof the canine.This is known as “The law of the canine”. SIMON’S CLASSIFICATION Deviation from the raphe or median sagittal plane . Arch form and inclination oftooth axis are determined from this plane.Contraction :A part or all of the dental arch is contracted toward the raphe median plane.The abnormalitymay be mandibular,alveolar,dental,anterior,posterior, unilateral or bilateral.Distraction : A part or all of the dental arch is wider than usual from the raphe median plane Deviations from the Frankfort horizontal plane : The angle between the Frankfort horizontal and the occlusal plane,the form of the occlusal curve, and the inclination ofthe teeth axes are determined from this plane.Attraction : The distance between the occlusal plane and the FH Plane is comparativelyshorter than normal. This distance is as a rule normallyshorter in the young than in older persons and in some ethnic groups.Abstraction : The distance between the occlusal plane and the FH plane is comparativelylonger than normal. SIMON’S CLASSIFICATION Deviations from the Orbital plane : Sagittal symmetryand inclination ofthe axes of the teeth are determined from this plane.Protraction : The teeth, one or both dental arches, and or jaws are too far forward.Normallythe orbital plane passes through the distal incline ofthe canine.Retraction : The teeth, one or both dental arches and or jaws are too far retruded.The orbital plane passes too far anteriorlyto the canines. SIMON’S CLASSIFICATION Deviations of the dental arches in relation to the orbital plane, according to Simon,may occur as follows:Both the jaws in normal relation to each other Upper jaw normal,lower jaw distal Upper jaw normal,lower jaw mesial Lower jaw normal,upper jaw mesial Lower jaw normal,upper jaw distal Upper jaw mesial,lower jaw distal Upper jaw distal,lower jaw mesial SKELETAL CLASSIFICATION: Malocclusion mayor may not be associated with facial dysplasia.Dental malocclusion maybe presentin an otherwise orthognathic face.However, normal occlusion mayalso be presentin a face which is not orthognathic.
- 6. Facial skeletal patterns are divided into Class 1,in which the profile is orthognathic,Class 2,where the mandible is retrognathic,and Class 3,in which the mandible is prognathic. Classification ofthe facial skeletal pattern takes into consideration also the relationship ofthe teeth as follows: Skeletal Class 1 : The bones of the face and the jaws are in harmonywith one another and with the restof the head. The maxilla is slightlyahead of the mandible.The profile is orthognathic.Division 1.Local malrelations ofincisor, canine or premolar teeth.Division 2. Maxillary incisor protrusion.Division 3.Maxillary incisors in linguovers ion. Division 4. Bimaxillaryprotrusion. SKELETAL CLASSIFICATION Skeletal Class 2 : Subnormal distal mandibular developmentin relation to the maxilla.Division 1. Maxillary dental arch is narrower than mandibular and there is crowding in the canine region,crossbite and reduced vertical height.Protrusion ofthe maxillary anterior teeth. The profile is retrognathic.Division 2. Lingual inclination ofthe maxillary incisors.The lateral incisors maybe normal or in labioversion SKELETAL CLASSIFICATION Skeletal Class 3 : Overgrowth of the mandible and obtuse mandibular angle.The profile is prognathic at the mandible. ACKERMAN – PROFFIT CLASSIFICATION: Ackerman and Proffit proposed a classification scheme for malocclusions in which five characteristics and their interrelationships are assessed.This system is a synthesis oftwo schemes,the Angle classification and the Venn diagram,both of which were proposed late in the nineteenth century by Angle and Venn. Venn proposed this representation in 1880,and it has become prominentin symbolic logic for computer use. INTRA ARCH ALIGNMENT IDEAL CROWDING SPACING PROFILE GROUP 1 GROUP 2 GROUP 3 GROUP 4 GROUP 5 Gp6 Gp7 Gp8 Gp9 VERTICAL DEVIATION Open Bite anterior Open bite posterior Deep bite anterior Collapsed bite posterior Skeletal Dental Anterior divergent Posterior divergentConvex Concave Straight TRANSVERSE DEVIATION Cross bites Buccal Palatal Unilateral Bilateral Skeletal Dental SAGITTAL DEVIATION Class IClass IIDiv1 Class IIDiv 2 Class IIISkeletal Dental TRANS-SAGITTAL SAGITO-VERTICAL VERTICO- TRANSVERSE TRANS-SAGITO-VERTICAL Classification bygroups Common to all dentitions is the degree of alignmentand symmetryof the teeth within the dental arches.This is represented as the universe (Group 1). Many malocclusions affectthe profile. For this reason, profile is represented as a major set(Group 2) within the universe.Lateral (transverse),anteroposterior (sagittal ),and vertical deviations and their interrelationships (Groups 3 to 9) are represented bythree interlocking subsets within the profile set. ACKERMAN – PROFFIT CLASSIFICATION Step 1 in the classification procedure is an analysis of the alignmentand symmetryof the teeth in the dental arches (interproximal contactrelationships).Alignmentis the key word of Group 1; among the possibilities are ideal ,crowding (arch-length deficiency), spacing ,and mutilated . Irregularities ofindividual teeth are described,ifdesired,by the method of Lischer,namely,the use of the suffix - version to describe the direction of individual tooth malalignments.Ideal occlusion,plus many(butby no means all) Angle Class Imalocclusions,would fall into Group 1. ACKERMAN – PROFFIT CLASSIFICATION In Step 2 one views the patient's profile.In the profile view, it should be noted whether the face is anteriorly divergent(mandible prominent) or posteriorlydivergent (mandible recessive) and whether the lips are convex (prominent),straight,or concave relative to the nose and chin. The "divergence" is mostoften related to the facial skeleton;lip position is stronglyinfluenced by the teeth. Lip and mouth posture should also be considered in the evaluation. : ACKERMAN – PROFFIT CLASSIFICATION In Step 3 the dental arches are viewed with regard to lateral dimensions (transverse plane),and the buccolingual relationships ofthe posterior teeth are note d. The term type is used to describe the various kinds ofcross-bite.A judgmentis also made as to whether the problem is basicallydentoalveolar or skeletal or due to a combination ofthe two. Buccal and palatal cross bites ( unilateral or bilateral) comes under this category
- 7. ACKERMAN – PROFFIT CLASSIFICATION In Step 4 the patientand dental arches are viewed in the anteroposterior dimension (sagittal plane).In this dimension,the Angle classification system is utilized and is merelysupplemented bystating whether a deviation is skeletal,dentoalveolar,or a combination.This information can be derived from observing the patient or more accuratelyfrom a cephalometric head film. ACKERMAN – PROFFIT CLASSIFICATION In Step 5 the patientand the dentition are viewed with regard to the vertical dimension.Bite depth is used to describe the vertical relationships.The possibilities are anterior open-bite,anterior deep-bite,posterior open-bite,or posterior collapsed bite . To determine whether this is on a skeletal,dentoalveolar ,or combined basis,a cephalometric analysis maybe particularlyhelpful. This approach defines nine groups ofmalocclusions.The complexity of the orthodontic problem increases with the group number.Thus,a Group 9 malocclusion is the mostcomplexin that there is an alignmentproblem,a problem in profile,and problems in the lateral, vertical, and anteroposterior dimensions as well. Advantages of this classification This method ofclassification based on five descriptive characteristics and defining nine groups ofmalocclusions overcomes the major weaknesses ofthe Angle system Specifically,arch-length problems,with or withoutan influence on the profile,are recognized;the influence of the dentition on the profile is taken into account All three planes ofspace,not justthe sagittal plane,are taken into consideration The differentiation between dental and skeletal problems is made atthe appropriate level Diagnosis is inherentin the classification ETIOLOGIC CLASSIFICATION: ETIOLOGIC CLASSIFICATION According to Moyers, Classification ofmalocclusion can be based on the origin of the problem.There are four classes depending on origin Skeletal or Osseous Dental Muscular Combination ofabove CONCLUSION: CONCLUSION The goal of modern orthodontics can be summed up as the creation of the best possible occlusal relationships within the framework ofacceptable facial aesthetics and stabilityof the occlusal result.The classification systems aid in diagnosis and treatmentplanning ofmalocclusions.There is a basic need for a system ofclassification of malocclusion thatwould be adequate for clinical,semantic and public health purpose and could be universally employed by those practicing the specialtythroughoutthe world