Occlusal development in children of African American descent. Types of terminal plane relationships in the primary dentition.

摘要

OBJECTIVE: To compare the types and depths of the terminal plane relationships (mesial step, distal step, and flush) in the primary dentitions of African American (AA) and European (E) children. MATERIALS AND METHODS: A convenience sample of 189 African American children (103 males and 86 females) was compared to a historical sample of 61 European children (39 males and 22 females, age range 2.1 to 5.2 years, mean age of 4.1 years). Plaster dental casts were analyzed for both samples. Terminal plane depth (TPD) was defined as the anteroposterior distance (APD) between the distal surfaces of the maxillary and mandibular second primary molars of dental casts registered in centric occlusion. Sample differences were evaluated using a 2-sample independent group t-test. RESULTS: Eighty-nine percent of African American children and 63% of European children exhibited a mesial step terminal plane. The average APD of the mesial step in African American children was 1.29 mm compared to 1.13 mm in European children, but this was not statistically significant (P = .18). The samples differed significantly (P = .001) in the average APD distal step relationship (AA, 1.08 mm vs E, 2.26 mm). The prevalence of distal step relationships was lower in African American children (5%) compared to European children (16%). African American children had a lower prevalence of flush terminal plane (6%) compared to European children (21%). CONCLUSIONS: In African American children as in European children, a mesial step, rather than a flush terminal plane, is the norm for the completed primary dentition.