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D.U.C Faculity of Dentistry 4th Grade Orthodontic Dr. Ghufran Dhari Lec.2 Inter-arch problems Saggital problems: Class II malocclusion: the lower dental arch and/or skeletal base is in distal relation to the upper dental arch (skeletal base), The mesio-buccal cusp of the upper first permanent molar occludes anterior to the buccal groove of the lower first permanent molar Class III malocclusion: the lower dental arch and/or skeletal base is in mesial relation to the upper dental arch (skeletal base), The mesio-buccal cusp of the upper first permanent molar occludes posterior to the buccal groove of the lower first permanent molar Class II Class III Vertical problems: Open bite: inherited, developmental or acquired malocclusion. There is no vertical overlap between maxillary and mandibular anterior teeth (anterior open bite), or no D.U.C Faculity of Dentistry 4th Grade Orthodontic Dr. Ghufran Dhari Lec.2 vertical contact is exhibited between maxillary and mandibular posterior teeth (posterior open bite). There are two types of open bite: Dental open bite: a localized open bite that involves only a few teeth due to a digit sucking habit or other local factors. Skeletal open bite: involve a larger number of teeth which is caused by divergence of the skeletal mandibular and/or maxillary planes leading to increased facial height as in case of posterior rotational growth of the mandible. Dental open bite Skeletal open bite D.U.C Faculity of Dentistry 4th Grade Orthodontic Dr. Ghufran Dhari Lec.2 Deep bite: the vertical overlap between maxillary and mandibular anterior teeth is increased beyond the normal range (more than 4mm), it is frequently associated with decreased vertical facial dimension. There are three types of deep bite: 1. None traumatic deep bite: in which the deep bite is still teeth to teeth relationship. 2. Traumatic deep bite: in which the deep bite associated with the impingement of the mandibular incisors in the mucosa palatal to the maxillary incisors commonly is seen in malocclusion with extremely deep bite as in sever class II malocclusion. 3. Bi-traumatic deep bite: usually seen in some cases of class II div. 2 malocclusion with minimal over jet, the retroclined maxillary incisors may impinge in the keratinized tissue labial to the mandibular incisors causing gingival recession at the same time there is a trauma to the palatal mucosa caused by lower incisors. Deep bite Traumatic deep bite Bi-traumatic deepbite D.U.C Faculity of Dentistry 4th Grade Orthodontic Dr. Ghufran Dhari Lec.2 • Transverse problems: Cross bite: An abnormal relationship or discrepancy of one or more teeth in dental arch to one or more teeth of opposing arch in buccolingual or labiolingual direction. A cross bite could be dental or skeletal in etiology. Anterior cross bite: if one or more of the lower incisors are in front of the upper incisors, this condition is called reverse overjet. Anterior cross bite Buccal cross bite: the buccal cusps of the mandibular posterior teeth occlude buccally to the buccal cusps of the maxillary posterior teeth. It could be: Unilateral cross bite: affect only one side of the dental arch. It could be either: 1. True unilateral cross bite: caused by an asymmetry present in the dental arch and usually does not associated with deviation of the mandible on closure . 2. False unilateral cross bite: caused by narrowing of the maxilla or widening of the mandible leading to cusp to cusp relation, this situation is uncomfortable to the patient so the patient tries to get maximum intercuspation by deviation of the mandible to one side leading to the development of unilateral cross bite. D.U.C Faculity of Dentistry 4th Grade Orthodontic Dr. Ghufran Dhari Lec.2 False unilateral cross bite Bilateral cross bite: affected both sides of dental arch and caused by severe maxillary collapse and/or mandibular widening, there is no mandibular deviation during closure. Bilateral cross bite Lingual cross bite(Scissor bite): the buccal cusps of the mandibular posterior teeth occlude lingually to the palatal cusps of the maxillary posterior teeth without contact of their occlusal surfaces and exhibit a vertical overlap. Lingual cross bite D.U.C Faculity of Dentistry 4th Grade Orthodontic Dr. Ghufran Dhari Lec.2 Scissor bite: is present when one or more of the adjacent posterior teeth are either positioned completely buccally or completely lingually to the antagonist teeth without contact of their occlusal surfaces and exhibit a vertical overlap. Midline shift (deviation): occur when the upper and lower dental midline are not coincide. A midline shift of 0.5 could be considered as a normal The midline shift could be: Associated with mandibular deviation during closure due to presence of premature contact. Not associated with mandibular deviation during closure as in case of unilateral missing of tooth or crowding. Midline shift may be due to shift of the upper midline only or shift of the lower midline only or sometimes both of them. It’s important to differentiate between midline shift of dentition and face. We may see one of them or sometimes both of them. D.U.C Faculity of Dentistry 4th Grade Orthodontic Dr. Ghufran Dhari Lec.2 Midline shift of the face mostly caused by abnormal skeletal factor (unilateral hyperplasia of the mandible or deviation of nose). Midline shift of dentition mostly associated with unilateral (extraction, congenital missing or impaction) of a tooth. Classification of malocclusion Classification of dental arch relations: Angle classification Classification of malocclusion was introduced by E.H. Angle, based on the anteroposterior relationship of the maxillary and mandibular permanent first molar. Angle’s classification: Class I malocclusion (Neutrocclusion): The mesio-buccal cusp of the upper first permanent molar occludes in the buccal groove between the buccal and middle cusps of the lower first permanent molar. D.U.C Faculity of Dentistry 4th Grade Orthodontic Dr. Ghufran Dhari Lec.2 The term class I malocclusion should be distinguished from class I normal occlusion, the term “class I” is sometimes used incorrectly as a synonym for normal occlusion, although in reality, it only signifies a sagittal (antero-posterior) relationship of maxillary and mandibular permanent 1st molars. In class I malocclusion, the upper& lower permanent 1st molars in normal or correct antero-posterior relationship but there are other problems within dental arch like: spacing, crowding, impaction, rotation, deep bite, increased over jet etc.. Class II malocclusion (Distocclusion)(Postnormal occlusion): The mesio-buccal cusp of the upper first permanent molar occludes anterior to the buccal groove of the lower first permanent molar. The severity of class II malocclusion is determined by fraction of cusp or unit. For example class II malocclusion half cusp or full cusp. D.U.C Faculity of Dentistry 4th Grade Orthodontic Dr. Ghufran Dhari Lec.2 Mesiobuccal cusp Anterior buccal groove Class II malocclusion can be divided into: Class II malocclusion, Division 1: class II malocclusion with proclined maxillary incisors resulting in an increased over jet with incomplete over bite or mostly deep bite. D.U.C Faculity of Dentistry 4th Grade Orthodontic Dr. Ghufran Dhari Lec.2 Class II malocclusion, Division 2: class II malocclusion typically with the maxillary incisors tipped palatally, a short anterior lower face height, deep bite and normal or decreasing over jet. The types of class II div.2 Type A: the four maxillary permanent incisors are tipped palatally. Type B: the maxillary central incisors are tipped palatally and the maxillary lateral incisors are tipped labially. Class III malocclusion (Mesiocclusion)( Prenormal occlusion): The mesio-buccal cusp of the upper first permanent molar occludes posterior to the buccal groove of the lower first permanent molar. The severity of class III malocclusion is determined by fraction of cusp or unit. For example class III malocclusion half cusp or full cusp. Mesiobuccal cusp Anterior buccal groove D.U.C Faculity of Dentistry 4th Grade Orthodontic Dr. Ghufran Dhari Lec.2 Pseudo class ІІІ (FALSE or postural): This is not a true class ІІІ malocclusion but its presentation is similar. Here the mandible shifts anteriorly during final stages of closure due to the presence of premature contact of the incisors or the canines. Pseudo class ІІІ Angle classification Angle’s system of classification is the most traditional and oldest system still in used, practical and easy to comprehend, widely used for teaching purpose. Angle’s system of classification based on the permanent 1st molar. So, when the permanent 1st molar is missing we should shift to another classification which is canine classification and if there is impacted canine or missing we shift to incisor classification. Angle’s system of classification describes only the antero-posterior (sagittal) relationship for permanent first molar and does not take in to account many other D.U.C Faculity of Dentistry 4th Grade Orthodontic Dr. Ghufran Dhari Lec.2 important relationships in the anteroposterior (overjet, canine relationship), in transverse relationship (crossbite) and vertical relationship (open &deep bite). Angle’s system of classification does not identify intra-arch problems such as spacing, crowding, rotation, missing or impacted teeth. Angle’s system of classification describes only the dental antero-posterior (sagittal) relationship which is not necessarily the same as the underlying sagittal skeletal relationship. Sometimes, the Angle’s classification is not symmetrical on both sides for example, we can find class II molar relationship on left side and class I molar relationship on right side, this is called CLASS II SUB-DIVISION Condition in which class III molar relationship is present only on one side with normal relation on the other side, this is called CLASS III SUB-DIVISION Canine classification Class I canine relationship: when the tip of upper canine located in the embrasure area between lower canine and 1st premolar in occlusion. (the mesial slope of upper canine coincide with distal slope of lower canine) in occlusion. D.U.C Faculity of Dentistry 4th Grade Orthodontic Dr. Ghufran Dhari Lec.2 Class II canine relationship: When the mesial slope of upper canine is ahead of the distal slope of lower canine in occlusion. Class III canine relationship: When the mesial slope of the upper canine lies behind the distal slope of the lower canine in occlusion. Incisor classification The incisor relationship does not always match the buccal segment (Angle classification). Since much of the orthodontic treatment is focused on the correction of incisor malrelationship, it is helpful to have a classification of incisor relationship. D.U.C Faculity of Dentistry 4th Grade Orthodontic Dr. Ghufran Dhari Lec.2 Class I incisor relationship: the lower incisor edges occlude with or lie immediately below the cingulum plateau (middle part of the palatal surface) of the upper central incisors. Class II incisor relationship: The lower incisor edges lie posterior to the cingulum plateau of the upper incisors. There are two divisions of class II incisor relationship: DIVISION 1: The upper central incisors are proclined or of average inclination & there is an increase in overjet. DIVISION 2: The upper central incisors are retroclined. The overjet is usually minimal or may be increased. Class III incisor relationship: The lower incisor edges lies anterior to the cingulum plateau of the upper incisors. The overjet is reduced or reversed. Classification of dental base (skeletal bases) relations The terms skeletal class I, II, III are commonly applied to describe dental base relations in the antero-posterior direction when the jaws are closed and the teeth in full occlusion. D.U.C Faculity of Dentistry 4th Grade Orthodontic Dr. Ghufran Dhari Lec.2 Skeletal class I: The jaws are in their ideal antero-posterior relationship in occlusion. Skeletal class II: The lower jaw in occlusion is positioned further back in relation to the upper jaw. This could be due to: a small mandible, a large maxilla or a combination of both. Skeletal class III: The lower jaw in occlusion is positioned further forward in relation to the upper jaw. This could be due to: a large mandible, a small maxilla or a combination of both. Skeletal cl I Skeletal cl II Skeletal cl III