Dental development in hemifacial microsomia. I. Eruption and agenesis.

The extent of anomalies and developmental aberrations in hemifacial microsomia (HFM) have not yet been fully delineated. Thus, the developmental pattern of the dentition in patients with HFM remains unclear. This study was conducted to investigate the development of the dentition in subjects with varying degrees of HFM and to compare the affected side with the unnaffected side and with data from control samples. Detailed tracings of the complete dental profile of 60 patients with HFM between the ages of 6 and 24 years were obtained from panoramic radiographs. The degree of development of each tooth was compared to Nolla's stages of tooth calcification, and developmental scores were assigned. The present study demonstrates that in individuals with HFM: (1) tooth development is frequently delayed on the affected side; (2) the mandibular third molar is more frequently missing on the affected than on the unaffected side; and 3) the incidence of missing teeth is higher than in unaffected subjects. A possible linkage between tooth development aberrations and the pathogenesis of HFM is discussed. Hemifacial microsomia (HFM) is a predominantly unilateral malformation of craniofacial structures that develop from the first and second branchial arches. Characteristic features of HFM are the underdevelopment of the mandibular condyle and ramus, the zygoma tic arch and malar bone, and associated soft tissues. Asymmetric tooth maturation and tooth agenesis also have been found in patients with HFM (Rushton 1953; Loevy and Shore 1985). However, the extent of dental anomalies in patients with HFM has not yet been fully investigated, and the developmental pattern of the dentition in these patients remains unclear. This study was conducted to determine whether a difference exists in the development of the dentition on the affected side compared with the unaffected side in patients with varying degrees of HFM. In addition, the development of the dentition in patients with HFM was compared to that in the general population. 1 Poswillo 1973; Vargervik and Miller 1983; Vargervik et al. 1986; Zbynek 1986. Materials and Methods Tooth development and agenesis were studied in 60 patients (24 boys, 36 girls) with HFM treated at the Center for Craniofacial Anomalies, University of California, San Francisco. They ranged in age from 6 to 24 years and were divided into four groups (Fig 1): younger than 10 (N = 12); 10-13 (N = 35); 14-17 (N = 7); and FIG 1. Comparison between delay in tooth development on the affected (A) and the unaffected side (N/A) in subjects with HFM grouped by age (P < 0.001, significantly different). older than 17 (N = 6). Patients younger than 14 years were excluded from the assessment of third molar agenesis because 14 years is considered a cut-off age for determining if this tooth will develop (Banks and Harry 1934; Garn and Lewis 1962). Patients were grouped according to the extent of mandibular deformity (Chierici 1983): type I — absence of condylar cartilage and disc; type II — no condylar head or neck on condylar process; type III — ankylosis or syndesmosis of joint; type IV — presence of coronoid process only; and type V — coronoid and condylar processes missing. The patient sample was composed as follows: type I — 26 (43%); type II — 3 (5%); type III — 4 (7%); type IV— 17 (28%); and type V — 10 (17%). Detailed tracings of the complete dental profile of each patient were obtained from panoramic radiographs (Fig 2—next page). The degree of development of each tooth was evaluated and compared with Nolla's stages of tooth calcification (Nolla 1960), and a developmental score was assigned. Data were com140 DENTAL DEVELOPMENT IN HFM: Farias and Vargervik