Morphologic determinants in the etiology of class III malocclusions: A review

Abstract

Morphospatial disharmony of the craniomaxillary and mandibular complexes may yield apparent mandibular prognathism, but Class III malocclusions can exist with any number of aberrations of the craniofacial complex. Deficient orthocephalization of the cranial base allied with a smaller anterior cranial base component has been implicated in the etiology of Class III malocclusions. Whereas the more acute cranial base angle may affect the articulation of the condyles resulting in their forward displacement, the reduction in anterior cranial size may affect the position of the maxilla. As well, intrinsic skeletal elements of the maxillary complex may be responsible for maxillary hypoplasia that may exacerbate the anterior crossbite seen in the Class III condition. Conversely, with an orthognathic maxilla, condylar hyperplasia and anterior positioning of the condyles at the temporo‐mandibular joint may produce an anterior crossbite. Aside from the skeletal components, soft tissue matrices, particularly labial pressure from the circumoral musculature, may influence the final outcome of craniofacial growth of a child skeletally predisposed to Class III conditions. Indeed, as some Asian ethnic groups demonstrate an increased prevalence of Class III malocclusions, it is likely that the skeletal components and soft tissues matrices are genetically determined. Presumably, the co‐morphologies of the craniomaxillary and mandibular complexes are likely dependent upon candidate genes that undergo gene‐environmental interactions to yield Class III malocclusions. The identification of such genes is a desirable step in unraveling the complexity of Class III malocclusions. With this knowledge, the clinician may elect an early course of dentofacial orthopedic and orthodontic treatments aimed at preventing the development of Class III malocclusions. Clin. Anat. 12:382–405, 1999. © 1999 Wiley‐Liss, Inc.

Evaluation of soft tissue parameters for adults with accepted occlusion using Legan and Burstone analysis

“…With an obtuse angle all the procedures that reduce prominence of the chin should be avoided. The finding coincide with the result obtained by Jain and Kalra [16] in which they reported that lower faceethroat angle was more obtuse in males than females and also AL-Jasser (2003) [22] study of selected Saudi population suggested that, lower faceethroat angle in males greater than females 109.90 and 102.90 respectively. When the lip form was assessed, the upper lip as well as lower lip was found to be more protrusive in males than in females and hence, the nasolabial angle was more acute, but the difference in nasolabial angle was statistically insignificant.…”

“…Sometimes the esthetic result is more important to the patient than the occlusal changes. Hence, good occlusion and improved facial appearance are distinct yet parallel objectives of orthodontic treatment [16].…”

Cephalometric assessment of maxillary length in Serbian children with skeletal class III

“…Many authors are also convinced that vomero-palatine suture is important for anterior-inferior displacement of palatal bone. Traumatic nasomaxillary complex leads to abnormalities in the growth of nasal septum, and surrounding muscle dysfunction may affect the subsequent growth of the facial massif 7 . Accordingly, the growth of nasomaxillary complex is the result of two main mechanisms: passive transfer, which is due to the growth of cranial base, which "pushes" maxilla forward and active growth of maxillary and nasal structures.…”

Orthodontic-surgical treatment of the skeletal class III malocclusion: A case report

“…Skeletal class III malocclusion is a classic example of "easy to be recognized but difficult to treat", the situation where sometimes orthodontic possibilities are limited and need support from other specialties, particularly surgery [22][23][24] . However, the key to a successful treatment lies in understanding and integrating these two specialties in seeking the best alternatives and procedures, as it was in our case where the treatment was carried out through orthodontic preparation and orthognathic surgery.…”