What kind of third molars are disease-free in a population aged 30 to 93 years?

Abstract

Objectives: The aim of the study was to characterize third molars that have remained disease-free in a representative sample of the Finnish population aged 30 years and older.

Materials and methods: Two-staged stratified cluster sampling (N = 8028) was used, and 6005 subjects participated in a clinical oral examination and panoramic radiography. Disease-free third molars were characterized as follows: no dentinal caries, no filling, periodontal pocket depths of neighboring second molars less than 4 mm, and no radiographic pathological findings. Logistic regression analyses served for assessment of the strength of characteristics of third molars for disease-free status.

Results: Of the subjects, 2653 (44%) had at least one third molar. Of them, the majority (62%) had only diseased third molars, 16% had only disease-free ones, and 22% had both. Participants had in total 5665 third molars; 29% of them were disease-free. Female gender, higher level of education, and younger age were related to disease-free status (P < 0.001). Disease-free status was more likely for third molars at cervical or apical level than at occlusal level: odds ratio was 10.1 for all teeth, 8.5 for maxillary teeth, and 6.2 for mandibular teeth.

Conclusion: A third molar situated deeper in the bone was more likely to be disease-free than a tooth at occlusal level in the population aged 30 years and older.

Clinical relevance: Our results suggest that the number of disease-free third molars decreased with increasing age, and most dramatically, this occurred among teeth at cervical level with the neighboring second molar.

Keywords: Adult population; Epidemiology; Panoramic radiograph; Pathology; Third molar.