Anomalies of permanent tooth number in three Asian ethnicities

Objective

The objective of this comparative study was to determine the proportion and distribution of tooth number anomalies in the permanent dentition in a sample of Chinese, Indian and Malay orthodontic patients in Singapore.

Methods

The cross-sectional study was carried out using radiographic and clinical data from the National Dental Centre of Singapore. Panoramic radiographs and clinical records of 1080 (Chinese (N = 415), Indian (N = 317) and Malay (N = 348)) orthodontic patients aged 12 to 16 years were examined for evidence of tooth number anomalies. Fisher’s exact test was applied to compare the occurrence of hypodontia and hyperdontia between the ethnicities and genders.

Results

The prevalence of hypodontia in Chinese, Indian and Malay orthodontic patients was 13.7%, 6.0% and 14.4%, respectively. Chinese patients had a significantly higher prevalence of hypodontia compared with Indian patients (OR 2.50, 95% CI 1.29–4.83, p < 0.001). Malay patients had a significantly higher prevalence of hypodontia compared with Indian patients (OR 2.63, 95% CI 1.34–5.17, p < 0.001). The most commonly missing tooth in the Indian patients was the upper lateral incisor (39.0%), whereas that in the Chinese and Malay patients was the lower second premolar (26.1% and 26.2%, respectively).

The prevalence of hyperdontia in Chinese, Indian and Malay patients was 7.0%, 3.8% and 7.8%, respectively. Male patients had a significantly higher prevalence of hyperdontia compared with female patients (OR 1.87, 95% CI 1.14–3.07, p = 0.015). Supernumerary teeth occurred more frequently in the anterior maxilla (34.1%) than in other regions of the jaws. Supernumerary teeth also occurred more frequently in the maxilla (76.9%) than in the mandible (23.1%).

Conclusion

There are significant differences in the presentation of anomalies in tooth number in the permanent dentition of Chinese, Indian and Malay orthodontic patients in Singapore.