Patterns of incisor-premolar agenesis combinations: A retrospective study

Tooth agenesis is the most common dental anomaly which causes serious problems in humans. Many theories were asserted to explain the main etiologic factor of this anomaly, and genetic factors were considered as primary reasons.

The aim of the present study was to evaluate the relationship between incisor and premolar tooth agenesis and to reveal a considerable data about combinations of incisor-premolar agenesis and their frequency.

According to inclusion and exclusion criterion, archived panoramic radiographs of nonsyndromic 6535 patients (4077 females and 2058 males) ranging in age from 7 to 18 years old were retrospectively examined to find the presence of tooth agenesis. Panoramic radiographs showing at least one tooth agenesis were recorded, and the missing tooth or teeth excluding third molars were noted.

Combinations of incisor-premolar tooth agenesis were listed, and the most affected teeth groups were noted.

Collected data were statistically analyzed using Chi-square test or Fisher exact's Chi-square test.

Three hundred and eight patients (4.7%) who had at least one tooth agenesis and 648 missing permanent tooth, excluding third molars, were detected. Although the sample size of females was bigger than males in all examined patients, tooth agenesis was detected significantly more in males than females (P = 0.021). Thirty-two patients (10.4%) had both incisor and premolar agenesis, and of all patients, twenty patients (6, 5%) were found to have both maxillary lateral incisor and mandibular second premolar agenesis.

Combinations of tooth agenesis are an issue which has begun to take attention recently. The results of the present study may provide empirical data for further genetic studies.