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Certain mutations in the COL1A1 and COL1A2 genes produce clinical symptoms of both osteogenesis imperfecta (OI) and Ehlers-Danlos syndrome (EDS) that include abnormal craniofacial growth, dental malocclusion, and dentinogenesis imperfecta. A mouse model ( Col1a1Jrt/+) was recently developed that had a skeletal phenotype and other features consistent with moderate-to-severe OI and also with EDS. The craniofacial phenotype of 4- and 20-wk-old Col1a1Jrt/+ mice and wild-type littermates was assessed by micro–computed tomography (µCT) and morphometry. Teeth and the periodontal ligament compartment were analyzed by µCT, light microscopy/histomorphometry, and electron microscopy. Over time, at 20 wk, Col1a1Jrt/+ mice developed smaller heads, a shortened anterior cranial base, class III occlusion, and a mandibular side shift with shorter morphology in the masticatory region (maxilla and mandible). Col1a1Jrt/+ mice also had changes in the periodontal compartment and abnormalities in the dentin matrix and mineralization. These findings validate Col1a1Jrt/+ mice as a model for OI and EDS in humans.

The role played by genetic components in the etiology of the Class III phenotype, a class of dental malocclusion, is not yet understood. Regions that may be related to the development of Class III malocclusion have been suggested previously. The aim of this study was to search for genetic linkage with 6 microsatellite markers (D1S234, D4S3038, D6S1689, D7S503, D10S1483, and D19S566), near previously proposed candidate regions for Class III. We performed a two-point parametric linkage analysis for 42 affected individuals from 10 Brazilian families with a positive Class III malocclusion segregation. Analysis of our data indicated that there was no evidence for linkage of any of the 6 microsatellite markers to a Class III locus at θ = zero, with data supporting exclusion for 5 of the 6 markers evaluated. The present work reinforces that Class III is likely to demonstrate locus heterogeneity, and there is a dependency of the genetic background of the population in linkage studies.

A female coarse-haired wombat held in captivity at the San Diego Zoo from approximately 2 to 16 years-of-age developed a dental malocclusion as a consequence of tooth overgrowth. The incisor, premolar, and molar teeth in this species are classified as aradicular hypsodont and continue to grow throughout life, presumably to counter the abrasive character of the high fiber, high ash, and high silica natural diet. In this case, there was a developmental defect of the maxillary incisor teeth, preventing functional interaction of the maxillary and mandibular incisor teeth. In addition, the captive diet appeared to be insufficiently abrasive, resulting in overgrown and malaligned premolar and molar teeth that were progressively less effective in food mastication and impinged on the tongue and buccal mucosa resulting in soft tissue lesions. The wombat was humanely euthanized, and comparisons of skull appearance and tooth position were made with those features in a wild-caught zoological specimen from the Smithsonian Institution.

Although James Costen was not the first to ascribe ear pain, tinnitus, impaired hearing, and even dizziness to temporomandibular joint dysfunction, he developed an integrated and systematic approach ascribing the symptoms to dental malocclusion. He wrote extensively on it, and a few years after his original article, the term Costen's syndrome came into general use. Recently, the use of the eponym has decreased, as dental malocclusion has assumed a lesser role in explaining many of the symptoms formerly ascribed to it.

Allergic rhinitis affects up to 20 per cent of the pediatric population and occurs in children of all ages. Secondary infection, dental malocciusion and a variety of other sequelae may complicate the primary disorder. The diagnosis of allergic rhinitis is based on historic features, physical findings and selected laboratory investigations. Treatment may involve antigen avoidance programs and immunotherapy. However, pharmacotherapy with antihistamines, sym pathomimetics and, in severe cases, corticosteroids, is most frequently used.

Dental malocclusion is present in all societies but its prevalence varies. There is a need to identify the occlusal problems, their incidence and the need for treatment so that appropriate manpower arrangements may be made. In this initial survey, patients attending the orthodontic clinic at the Riyadh Armed Forces Hospital were examined for occlusal relationship, crowding, and facial type. There are indications amongst Saudi Arabian patients of a tendency for bimaxillary proclination and a greater proportion of Class III malocclusion, than in Western communities. The need for a comprehensive survey is identified.