The prevalence of MIH in the permanent dentition of Hong Kong Chinese children was 2.8%. Children with MIH showed higher caries experience in the permanent dentition than the general population of similar age.

Abstract:The published literature on tooth transposition includes only a few studies that have involved more than 50 subjects. The aim of the present study was to investigate the prevalence of true maxillary tooth transposition and possible associated dental anomalies in a larger sample of children. The dental records and radiographs of children who had been diagnosed as having true maxillary tooth transposition at a School Dental Clinic in Hong Kong were studied retrospectively. Data were analyzed for sex and side distribution, as well as for associated dental anomalies. Trends of differences were analyzed statistically using the Fisher exact or chi-squared test. A total of 69 cases of true maxillary tooth transposition were identified and studied; its prevalence in Hong Kong Chinese children was 0.81%. More females than males were affected, and the difference between the sexes was statistically significant (P < 0.05). The prevalence of congenitally missing teeth, microdontia of the maxillary lateral incisors or dental impaction was higher in patients with maxillary tooth transposition than in the general population (P < 0.05, P < 0.0005, and P < 0.0001, respectively). The fact that patients with maxillary tooth transposition were more likely to have congenital absence or microdontia of the maxillary lateral incisors lent further support to the contention that a developmental field defect plays a role in the pathogenesis of maxillary tooth transposition. (J Oral Sci 54, 197-203, 2012)

Supernumerary premolars appeared to be more prevalent in Chinese children with dens evaginatus than in the general population. There may be an association of supernumerary premolars with dens evaginatus in this study population.

Children with true talon cusps on the permanent maxillary incisors were more frequently affected by supernumerary teeth in the anterior maxilla. Further studies with a larger sample are needed to confirm a true association.

Artefacts in dental radiographs are not uncommon findings. In some cases, however, such film faults might lead to difficult or even wrong diagnoses. In this brief report, the authors present a case where a small piece of paper cast a foreign body-like image onto a panoral radiograph. The importance of proper techniques and film handling when taking radiographs cannot be over-emphasised.