Occlusal characteristics during different emergence stages of the permanent dentition in Tanzanian Bantu and Finnish children

Occlusal characteristics and anomalies were studied among 869 (428 boys, 441 girls) Tanzanian Bantu children aged 3.5-16 years and 706 (319 boys, 387 girls) Finnish children aged 5-11 years during different emergence stages of the permanent dentition. Various occlusal variables were registered according to described criteria. Multiple linear regression, ANOVA, t-test, Chi-square and logistic regression models were used to test for various statistically significant differences between different subgroups. Significant differences between Tanzanians and Finns were found for malocclusion, neutral and distal molar occlusion, mean values for overjet and overbite, overjet greater than 5 mm, deep bite and anterior open bite (all P < 0.0001). The most prevalent anomalies among Tanzanians were anterior open bite (7-19 per cent), increased overjet (3-19 per cent) and distal molar occlusion (3-16 per cent). For the Finns, distal molar occlusion (18-38 per cent) was the most prevalent anomaly, followed by deep bite (4-22 per cent) and increased overjet (4-40 per cent). An anterior crossbite was rare and equally distributed among the two ethnic groups. Girls had a larger mean value for overbite (P = 0.003) and more often a deep bite (P < 0.01) than boys. Mandibular incisor crowding among children with neutral occlusion (Class I malocclusion) occurred significantly more often among Finnish than Tanzanian children. In conclusion, various developmental changes in occlusion were observed leading to variation in occlusal characteristics and anomalies according to the emergence stages of the permanent dentition. Most of the classic malocclusions occur among Tanzanian children, but the prevalence differs from that in other parts of the world.