Segmental odontomaxillary dysplasia: report of a series of 5 cases with long-term follow-up.

We report a series of 5 cases of segmental odontomaxillary dysplasia (SOMD) with follow-up periods ranging from 8 to 21 years, bringing the total number of reported cases to 45. SOMD is a sporadic, mesoectodermal dysplasia that presents early in life, possibly as early as in utero and exhibits male gender predominance (1.7:1.0). Its features include enlargement of the soft tissue and/or bone of 1 hemimaxilla that may produce mild facial asymmetry. Subsequent growth of the affected area is proportional to that of the unaffected hemimaxilla. Sclerotic radiographic bone changes and dental developmental abnormalities are also present. The dense bone, which often exhibits a radiographic vertical orientation of the trabecular bone pattern, is typically associated with delayed eruption of the teeth. Congenitally missing premolar teeth (either or both) is a common feature of this condition that is of significant diagnostic value. Although ipsilateral cutaneous findings have been reported in 23%, our cases exhibited none. Computed tomographic imaging demonstrated extensive involvement of the maxillary bone, including the lateral wall and floor of the maxillary sinus and the hard palate. The affected bone presents no impediment to either orthodontic tooth movement or to the successful osteointegration of dental implants. The cause of SOMD is unknown; the clues to the cause of this unusual phenotypic expression are buried in the intricacies of developmental biology within the first branchial arch.