Malocclusion Classification PDF

CLASSIFICATION OF MALOCCLUSION Mal- is a prefix added to words in order to form new words which describe things that are bad or unpleasant. Eg. Malnutrition, malformed, malocclusion. Definition: Malocclusion could be defined as: A condition where there is departure from the normal relation of the...

CLASSIFICATION OF MALOCCLUSION Mal- is a prefix added to words in order to form new words which describe things that are bad or unpleasant. Eg. Malnutrition, malformed, malocclusion. Definition: Malocclusion could be defined as: A condition where there is departure from the normal relation of the teeth to other teeth in the same dental arch and/or to teeth in the opposing arch. In normal occlusion, the line of occlusion passes through - The central fossae and along the cingulae of the maxillary teeth. - The buccal cusps and incisal edges of the mandibular teeth. Malocclusion can be created by: I. Malposition of individual teeth in normally related arches and bases, II. Malrelation of the dental arches on normally related bases, III. Malrelation of the apical bases – Maxilla and mandible. I- Malposition of individual teeth: Lischer used the suffix “version” to identify the malposition of teeth in relation to the line to of occlusion. 1- Mesioversion: Mesial to the normal position. A tooth in Mesioversion may be: Mesially inclined: The crown of the tooth is tipped mesially. Mesially displaced: The whole tooth is displaced mesially. 2- Distoversion: Distal to the normal position. 3- Labioversion: Towards the lip. 4- Buccoversion: Towards the cheeks. 5- Palatoversion: Towards the Palate. 6- Linguoversion: Towards the tongue. 7- Supraversion: Erupted past the line of occlusion. (Over erupted.) 8- Infraversion: Short of the line of occlusion. 9- Torsiversion: Rotated on its long axis. 10- Transversion: Wrong order in the arch—Transposition. 11- Imbrications: Teeth are irregularly placed in the arch due to the lack of space, especially lower incisors. II- Malrelation of the dental arches: Is described in the 3 planes of space Anteroposterior plane. Lateral plane. Vertical plane. For better understanding some light should be shed on the Orientation Planes used in human anatomy.  1- Sagittal Plane or Lateral Longitudinal Anteroposterior Median It is an imaginary plane parallel to the sagittal suture, that passes longitudinally through the middle of the head and divides it into right and left halves. Used to describe anterior-posterior relationships. 2- Frontal Plane or Coronal Plane or vertical plane. An imaginary plane that passes longitudinally through the head perpendicular to the sagittal plane dividing the head into front and Back. Used to describe transverse relationships. 3- Transverse Plane or Axial Plane or horizontal or transaxial An imaginary plane that passes through the head at right angles to the sagittal and frontal planes dividing the head into upper and lower halves. Used to describe right to left relationships. A) Anteroposterior malrelation of the dental arches: In the anterior region we evaluate the overjet. In the posterior region we evaluate molar and canine relation Normal overjet is 1-3 mm. Overjet could be normal, increased , edge to edge, or negative. Normally when the teeth are in centric occlusion and condyles are in the glenoid fossae, There should be a Class I molar and Class I canine relationships. Malrelation in this plane could be: 1-Postnormal Occlusion: When the teeth are in centric occlusion and the condyle are in the glenoid fossae, the lower dental arch is too far distally to the upper dental arch. Usually -but not always- manifested by an increased overjet (more than 3 mm)  2-Prenormal Occlusion: When the teeth are in centric occlusion and the condyles are in the glenoid fossae, the lower dental arch is mesial to the upper dental arch. Usually manifested by a reversed overjet (anterior crossbite) or an edge to edge bite 3-Postural prenormal occlusion: When the teeth are in centric occlusion the mandible is postured forward to make the lower arch in a mesial position to the upper arch (shift- bite of accommodation) In this case the condyles will be forward of the glenoid fossae. B) Transverse: (lateral) Anteriorly we evaluate upper and lower midlines. Posteriorly we evaluate cross bite Deviations of the midline. Maxillary and mandibular dental midlines could be non-coincident with facial midline, either upper, lower, or both. Normally the upper buccal cusps overlap the lower buccal cusps, and the upper palatal cusps occlude in the central fossae of the lower teeth Posterior Cross bite: l In a posterior cross bite one or more posterior teeth occlude in an abnormal buccolingual relation with their antagonist.  l It is possible to assign the arch at fault and the direction of the deviation in the name of the crossbite ( e.g. maxillary posterior buccal crossbite) l It could be unilateral or bilateral. Scissors bite: Several adjacent posterior teeth overlap vertically in habitual occlusion without contact of their occlusal surfaces. Deviation of the teeth could be buccal or lingual. Telescopic Bite: This is a complete maxillary buccal or mandibular lingual cross bite. Reverse telescopic bite is the opposite. i.e. has to be bilateral C) Vertical: Variation in the degree of the overbite: i. Deep overbite: if the overbite is excessive, it is called deep overbite or closed bite. This abnormality may be due to: o Supraposition of the anterior teeth o Infraposition of the buccal segments ii. Open bite: if the overbite is negative, it is called open bite. This term is applied when there is no vertical overlap of the upper and lower incisors (anterior), or when there is localized absence of occlusion posteriorly. Open bite is associated by abnormal soft tissue behavior patterns preventing the dentoalveolar structures from closing the intermaxillary space, e.g. thumb, lip and/or tongue. It can be also associated with an abnormal skeletal pattern. This abnormality may be due to: o Infrapositon of anterior teeth o Supraposition of posterior teeth III) Malrelation of the apical bases: Malrelation of the upper and lower apical bases is analyzed in three planes, similar to malrelation of the dental arches. (Anteroposterior, vertical and transverse) Those are most severe malocclusions; maybe the mandible is underdeveloped or overdeveloped. Same applies to the maxilla e.g. small maxilla due to cleft i.e. retrognathic or prognathic maxilla or mandible Assessment of the malrelation of the apical bases in the anteroposterior and vertical planes is done through the analysis of Lateral Cephalometric X-rays films. Assessment of the malrelation of the apical bases in the transverse plane is done through the analyses of Postero-anterior Cephalometric X-ray films. Relationship of the maxilla to the mandible: a. Skeletal Class I: when the maxilla and mandible are in normal anteroposterior relationship to each other. b. Skeletal Class II: when the mandible is in postnormal position relative to the maxilla. This may be due to a retrognathic mandible, prognathic maxilla or both. c. Skeletal Class III: when the mandible is in prenormal position relative to the maxilla. This may be due to a prognathic mandible, retrognathic maxilla or both. Skeletal class I Skeletal class II Skeletal class III Functional Malocclusion: Premature contacts may necessitate a displacement of the mandible to obtain a position of maximum intercuspation of the teeth. When the mandible is displaced, the teeth are in maximum intercuspation but the condyles are not in their normal position relative to the glenoid fossa. Could be anterior functional shift leading to anterior cross bite. Or Lateral (Transverse) shift leading to posterior cross bite. Good Luck