Malocclusion of Teeth PDF

# Malocclusion of Teeth ## Dental Arch - The dental arch is the arch formed by the crowns of the teeth. - The image shows the lower arch on the left and the upper arch on the right. - The lower arch has the following labels: - Lower arch - Incisors - Canine - Premolars - Molars...

# Malocclusion of Teeth ## Dental Arch - The dental arch is the arch formed by the crowns of the teeth. - The image shows the lower arch on the left and the upper arch on the right. - The lower arch has the following labels: - Lower arch - Incisors - Canine - Premolars - Molars - The upper arch has the following labels: - Upper arch - Incisors - Canine - Prematars - Molars ## Alveolar Bone - Alveolar bone is defined as the parts of maxilla and mandible that form and support the socket of teeth. ## Basal Bone - Basal bone is the osseous tissue of the mandible and maxillae except the alveolar processes - The image shows a diagram of the maxilla, with the following labelled parts: - Orbital surface - Zygomatic process - Maxillary bone - Frontal process - Infraorbital foramen - Anterior nasal spine - Alveolar margin ## Malocclusion - Malocclusion is defined as a condition where there is a departure from the normal relation of the teeth to other teeth in the same arch and to teeth in the opposing arch. - The image shows the difference between a normal occlusion on the left and a malocclusion on the right. ## Categories of Malocclusion - Malocclusion can be either: - Simple - Complex - Malocclusion can be further categorized by: - **Teeth:** Malpositioning of individual teeth or groups of teeth in normally related dental arches and jaws. An erupted or partially erupted tooth may occupy a position other than normal by being inclined. i.e., the crown of the tooth may occupy an abnormal position while its apex is normally placed. - The crown and the root of the tooth may be bodily displaced in the same direction. - A tooth may be rotated around its long axis. - *Intra-Arch Problems* - Saggital Problems - Labioversion - Linguoversion - Mesioversion - Distoversion - Vertical Problems - Supraversion - Infraversion - Rotation - Transposition - The various anomalies are designed according to the direction and nature of the malposition: - **Mesial displacement:** Describes a tooth which is bodily displaced toward the mid-line of the arch. - **Distal displacement:** Describes a tooth which is bodily displaced in direction away from the mid-line of the arch. - **Distal inclination:** The opposite of mesial inclination, where a tooth is tilted along the line of the dental arch so that its crown is too far away from the mid-line of the arch. - **Mesial inclination:** Mesial Inclination of the Crowns of the Central Incisors and Congenital Missing of the Laterals. - **Distal inclination:** Distal Inclination of the Crowns of the Centrals and Peg-Shaped Right Lateral Incisor. - **Lingual inclination:** Refers to a tooth so tilted that its crown leans towards the tongue. Retroclination is a term frequently used also to refer to the lingual tilting of the anterior teeth. - **Lingual displacement:** Describes a tooth that bodily displaced towards the tongue. - **Labial inclination** A term used to describe the outward tilting of incisor and canine teeth towards the lips (proclination may be used also to describe this condition). - **Labial and buccal displacement:** used similarly to describe bodily displacement of teeth in an outward direction. - **Infraocclusion:** A term used to describe a tooth of which the occlusal surface or incisal edge has not reached the same level as the rest of the teeth in the arch; i.e., it does not appear to have erupted sufficiently. - **Supraocclusion:** The opposite of infraocclusion; i.e., the tooth appears to have "over-erupted." - **Mesio-lingual rotation:** Describes a tooth which is rotated around its long axis so that its mesial aspect is turned towards the tongue. - **Disto-lingual rotation:** Describes a rotation in the opposite direction. - **Imbrication:** Describe teeth (especially lower incisors) which are irregularly arranged within the arch due to lack of space for them. - **Transposition:** A term used to describe a condition where two teeth appear to have exchanged places during the development of occlusion. perhaps this is most often seen where an upper canine and an upper first premolar or lateral incisor on the same side of the arch are transposed. - **Crowding:** Crowding is the lack of space for all the teeth to fit normally within the jaws. The teeth may be rotated or displaced. Crowding occurs when there is disharmony in the tooth-to-jaw size relationship or when the teeth are larger than the available space. Combinations of these individual malpositions may occur. e.g., An upper canine tooth may be in infra-labial inclination where it has erupted high in the sulcus and outside the dental arch, a position not infrequently assumed by the upper canine tooth. - **Dental arch:** Mal-relation of the dental arches to one another upon bony bases which are them-selves normally related. - **Inter-Arch Problems** - Saggital - Class 2 Malocclusion - Class 3 Malocclusion - Transverse - Crossbites - Midline Shift - Vertical - Deep Bite - Open Bite - Mal-relation of the dental arches can take place in all dimensions; antero-posteriorly, laterally and vertically. - **Dental bases (skeletal):** This refers to conditions where the upper and lower arches are abnormally related to each other in a sagittal plane. Such malocclusions can be of two types: - **Prenormal occlusion:** Where the lower arch is placed more anteriorly when the teeth meet in centric occlusion. - **Postnormal occlusion:** Where the lower arch is placed posteriorly when the teeth meet in centric occlusion. - **Vertical plane malocclusions:** Refer to conditions where there is an abnormal vertical relationship between teeth of upper and lower dental arches. They include deep bite and open bite cases. - **Deep bite/increased overbite:** Where there is excessive vertical overlapping of upper anterior over the lower anteriors when teeth are in central occlusion. - **Open bite:** Where there is lack of vertical relationship between upper and lower teeth. Open bite can be presented in the anterior or posterior regions - **Anterior open bite:** The term refers to conditions where there is no vertical overlap of upper anterior over the lower anterior when teeth are brought to centric occlusion. - **Posterior open bite:** The term refers to a condition where there is a lack of intercuspation between upper and lower posterior teeth, when teeth are in centric occlusion. Posterior open bite can be unilateral or bilateral. - **Transverse plane:** Refers to conditions where there is an abnormal transverse relationship between the upper and lower arches. These include various types of crossbites and scissor bites. - **Crossbite:** The term refers to a condition where one/more teeth may be abnormally malposed buccally, lingually or labially with reference to the opposing tooth or teeth. - **Scissors bite:** The term applies to total maxillary buccal (or mandibular lingual) crossbite with the mandibular dentition completely contained in habitual occlusion. ## Classification Systems for Malocclusion The following classification systems are commonly used to categorize malocclusion. ### Angle’s Classification of Malocclusion - In 1899 Edward H. Angle published the first classification of malocclusion. - The classification is based on the relationship of the mesiobuccal cusp of the maxillary first molar and the buccal groove of the mandibular first molar. - This classification has been modified to include additional categories. - Angle's classification included the following categories: - **Class I malocclusion:** THE MESIOBUCCAL CUSP OF THE UPPER FIRST PERMANENT MOLAR OCCLUDES WITH THE MESIOBUCCAL GROOVE OF THE LOWER FIRST MOLAR, BUT LINE OF OCCLUSION IS INCORRECT BECAUSE OF MALPOSED TEETH, ROTATIONS OR OTHER DISCREPANCIES - **Class II malocclusion:** Condition when class II molar relationship is present with proclined upper central incisors. There is an increase in overjet. - **Class II Division 1:** Condition when class II molar relationship is present with retroclined upper central incisors, upper lateral incisors may be proclined or normally inclined. Overjet is usually minimal or may be increased. - **Class II Division 2:** Condition when the class II molar relationship exists on only one side with normal molar relationship on the other side. - **Class III malocclusion:** THE MESIOBUCCAL CUSP OF THE LOWER FIST MOLAR OCCLUDES MESIAL TO THE CLASS I POSITION. - **Class III:** Due to occlusal prematurity, when the mandible moves from rest position to occlusion, it slides forward into a pseudo class III position. It's also known as postural class III. - **Class III Sub-division:** Condition in which class III molar relationship is present only on one side with normal relation on the other side. - **Merits:** - Easy & most practical method. - Rapid. - Requires no instrumentation. - Easy to communicate. - Widely used for teaching purposes. - **De-Merits:** - Incorrect Hypothesis. - Angle considered only saggital dimension. - Not applicable in deciduous dentition. - Not applicable when first permanent molars are missing. - Skeletal problems are not considered. - Didn’t elaborate the etiology of malocclusion. - **Drawbacks of Angle’s Classification** - Angle considered malocclusion only in the antero-posterior plane. He didn’t consider malocclusion in the transverse and vertical planes. - Angle considered the first permanent molars as fixed points in the skull. But, this is not found to be so. - The classification can’t be applied if the first permanent molars are extracted or missing. - The classification can’t be applied to the deciduous dentition. - The classification does not differentiate between skeletal and dental malocclusion. - The classification does not highlight the etiology of the malocclusion. - Individual tooth malposition has not been considered by angles. ### Modifications of Angle’s Classification - There are two modifications of Angle’s classification: - Lischer's modification - Dewey’s modification #### Dewey’s Modification (1915) - Martin Dewey divided Angle’s class I and III into further types: - **Class I:** - Type 1: Crowded maxillary anterior teeth. Canines may be abnormally positioned. - Type 2: Proclined or labioversion of maxillary incisors. - Type 3: Anterior cross bite present. - Type 4: Posterior cross bite present. - Type 5: Mesioversion of molars. - **Class III:** - Type 1: Well aligned teeth & dental arches. Edge-edge relationship. - Type 2: Crowded mandibular incisors. - Type 3: Crowded maxillary incisors, underdeveloped maxilla. Anterior cross bite present. - **Dewey’s classification:** No modification on class II. #### Lischer's Modification - He introduced following names to the Angle’s classification: - Neutrocclusion - Class I - Distocclusion - Class II - Mesiocclusion - Class III - Lischer termed Angles I, II, and III as neutro-occlusion, disto-occlusion, and mesio-occlusion. Other than these he added a few more terms in the classification of malocclusion such as: - **Bucco-occlusion:** Buccal placement of a tooth or a group of teeth. - **Linguo-occlusion:** Lingual placement of a tooth or a group of teeth. - **Supra-occlusion:** Erupted beyond normal level. - **Infra-occlusion:** Not erupted to normal level. - **Mesio and disto version:** Placed mesial or distal to normal occlusion.. - **Axiversion:** Abnormal inclination of a tooth. - **Torsiversion:** Tooth rotated around its long axis. ### British Standard Classification of Incisor Relationship (1983) - Based upon incisor relationship, proposed in 1983. - Do not consider molar relationship in some cases. - **Class I:** The lower incisor edges occlude with or lie immediately below the cingulum plateau of upper central incisors. - **Class II:** The lower incisor edges lie posterior to the cingulum plateau of the upper incisors. There are two sub-divisions: - **Division 1:** The upper central incisors are proclined or of average inclination and 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:** The lower incisor edges lies anterior to the cingulum plateau of the upper incisors. The overjet is reduced or reversed. - **Class I incisors relationship** Lower incisal edges occlude with or lie immediately below the cingulum plateau of the upper incisors. - **Class II incisors relationship:** The lower incisal edge lies posterior to the cingulum plateau of the upper incisors. - **Class II Division 1 incisor relationship:** The upper central incisors are proclined or of average inclination. There is an increase in overjet. - **Class II Division 2 incisor relationship:** The upper central incisors are retroclined. The overjet is usually minimal but may be increased. - **Class III incisors relationship:** The lower incisal edges lies anterior to the cingulum plateau of the upper incisor. ### Canine Classification - **Class I:** When the mesial slope of upper canine coincides with the distal slope of lower canine. - **Class II:** When the mesial slope of upper canine is ahead of the distal slope of lower canine. - **Class III:** When the mesial slope of the upper canine lies behind the distal slope of the lower canine. ### Simon's Classification (1926) - In Simon’s classification system, the dental arches are related to three anthropologic planes. - **Planes Used:** - Frankfort horizontal plane or eye-ear plane. - Orbital plane - Raphe median plane or mid-saggital plane. - **Frankfort Horizontal Plane:** - Helps detect deviations in the vertical plane. - Dental arch closer to the plane is called attraction and farther away is called abstraction. - **Orbital Plane:** - Helps to detect deviations in the transverse plane. - Dental arch more anteriorly placed is called protraction and posteriorly placed dental arch is called retraction. - **Mid-saggital Plane:** - Helps to detect deviations in the saggital plane. - Dental arch closer to mid-saggital plane is called contraction and farther away is called distraction. ### Skeletal Malocclusion - Skeletal malocclusion can be caused by defects in size, position, or relationship between the upper and lower jaws. - Skeletal malocclusions can occur in sagittal, vertical, and transverse planes. - **Skeletal Malocclusions in Sagittal Planes:** - These include conditions where the upper and lower jaws are abnormally related to each other in a sagittal plane. - The term prognathism refers to forward placement of a jaw and the term retrognathism is used for backward placement of a jaw. - Sagittal plane malocclusion can occur in one or both the jaws or as various combinations. - **Skeletal Malocclusions in Vertical Plane:** These malocclusions include open bite and deep bite conditions. - **Skeletal Occlusions in Transverse Plane:** Narrowing or widening of the jaws may result in an abnormal relationship between upper and lower jaws in a transverse plane. These include skeletal crossbite and scissor bite conditions, which may be unilateral/bilateral. ### Skeletal Classification - It considered relationship between maxilla and mandible, in antero-posterior direction. - **Class I:** Maxilla and mandible are in harmony with each other. - **Skeletal Class 1:** The bones of the face and the jaws are in harmony with one another and with the rest of the head. The maxilla is slightly ahead of the mandible. The profile is orthognathic - **Division 1:** Local malrelations of incisor, canine or premolar teeth. - **Division 2:** Maxillary incisor protrusion. - **Division 3:** Maxillary incisors in linguoversion - **Division 4:** Bimaxillary protrusion = edge to edge - **Class II:** Maxilla lies ahead of mandible with reference to anteroir cranial base. In other words, maxilla is prgnated. - **Skeletal Class 2:** Subnormal distal mandibular development in 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 of the maxillary anterior teeth. The profile is retrognathic. - Determine devision according to incisors. - **Division 2:** Lingual inclination of the maxillary incisors. The lateral incisors may be normal or in labioversion. - **Class III:** Maxilla lies posterior to mandible with reference to anterior cranial base. In other words, maxilla is retrognathed. - **Skeletal Class 3:** Overgrowth of the mandible and obtuse mandibular angle. The profile is prognathic at the mandible.