The study of tooth angulation and inclination for bracket design of Deutromalay race: A comparison study to white race.

Background: The Indonesian population consist of Deutromalay and Protomalay races, with the Deutromalay race being most of the population. In 1972, Lawrence F. Andrews introduced the "six keys of normal occlusion," which was based on a white sample. This study aimed to identify standard tooth angulation and inclination in the Deutromalay race, which might help in future development of bracket prescription specific to the population.

Methods: This cross-sectional study was conducted on a representative sample of 190 subjects (112 male and 78 female subjects) aged 14 to 22 years from the Deutromalay population. Data collection was performed by two investigators following the methodology prescribed by Andrews for measuring tooth crown angulations and inclinations. Inter-rater reliability was measured with kappa statistics. Data were analyzed using SPSS software, version 25. Independent-samples t-tests were used for significance testing. The alpha level for statistical significance was set at 0.05, two-tailed.

Results: The kappa statistic came out to be 0.80, which showed substantial agreement. The results of the t-test for tooth angulation and inclination found significant differences between male and female subjects for some teeth within the Deutromalay sample. In addition, significant differences were found for most teeth between the Deutromalay and white samples.

Conclusions: Significant differences in crown angulation and inclination values exist for most teeth in the Deutromalay sample studied compared with the white norms reported by Andrews. This points to the possible need to develop a new preadjusted bracket prescription specific for the Indonesian (Deutromalay) population.