José Rubén Herrera-Atoche; Gabriel Eduardo Colomé-Ruiz & Mauricio Escoffié-Ramírez

Prevalence of third molar agenesis has been estimated in 24.3% in Mexico. Dental agenesis is associated with other dental anomalies due its genetic origin. The aim of this study was to determine the prevalence and distribution of third molar agenesis and to establish its association with other dental anomalies in an orthodontic population. The sample included 670 orthodontic patients from 9 to 20 years old. Exclusion criteria were patients with previous orthodontic treatment and syndromic conditions. Third molar agenesis prevalence was calculated and sex values were compared. Then, patients were divided into 2 groups, with agenesis of at least one third molar and a control group; prevalence of 10 dental anomalies were calculated for both groups. The results were compared using Fisher's exact test (p <0.05). Third molar agenesis prevalence was 25.97%, there was no statistical difference between sexes (p= 0.139). The 41.95% of patients in the agenesis group had abnormalities associated, whereas in the control group it was 23.59%. A significant difference between groups was found (p= 0.0001). When comparing the prevalence of each individual anomaly between groups, it was found that agenesis (p= 0.0001) and impacted teeth (p= 0.015) were significantly decreased in the control group. In conclusion it was found a prevalence of 25.97%, with no sex preference. Patients with agenesis of third molars have a higher prevalence of associated dental anomalies, particularly agenesis of other teeth and impacted teeth.

KEY WORDS: Agenesis; Prevalence; Third molar; Tooth abnormalities.

HERRERA-ATOCHE, J. R.; COLOMÉ-RUIZ, G. E. & ESCOFFIÉ-RAMÍREZ, M. Third molar agenesis, prevalence, distribution and association with other dental anomalies. Int. J. Morphol., 31(4):1371-1375, 2013.