Polymorphism in sequence of permanent tooth emergence in Czech children

The aim of the study is to determine norms of polymorphic variation in the sequence of permanent teeth in Czech children in order to establish first standards applicable to individuals. Setting out such standards, derived from the population to which they will be applied, are essential for diagnoses in paediatric dentistry, orthodontic treatment planning and for anthropological application.

Dental examinations were performed on a sample of 1,370 children (696 girls and 674 boys) aged 4-15 years. All emerged permanent teeth (other than third molars), when at least some part of crown has penetrated the oral mucosa, and the child's gender were recorded. The frequency of sequence polymorphism was calculated for each gender by counting instances of absent/present and present/absent across all possible intra-arch and inter-arch tooth pairs.

Differential frequencies of polymorphic sequences were more common in the inter-arch tooth pairs than in the intra-arch pairs. The most similar frequencies in inter-arch pairs were observed in second mandibular premolar/second maxillary premolar in both genders. However, in the mandible there was a polymorphic sequence in the first molar/central incisor pair in both genders. Furthermore, mandibular polymorphisms were more commonly observed in the sequences of canine/second premolar in girls than in boys. Additionally, canine/second premolar polymorphic sequences were found to be more common in the maxilla in both genders.

The data presented in this article are useful in the prediction of tooth emergence sequence in individual Czech children and are important in paediatric dentistry and in orthodontic treatment.