Gender Ratios in Dental Anomalies of Number

Objective: Many theories have been proposed to explain dental anomalies of number. Tooth agenesis (TA) is more common in females and supernumerary teeth (ST) are more common in males. The aim of this work was to investigate a large cohort of children to explore in more detail the clinical presentation of these traits, investigating if some specific patterns of TA and ST (subphenotypes) show gender preferences.

Methods: Orthopantamograms of 1198 subjects were examined and 1167 were used in this study.

Results: No TA cases presented concomitant ST. The frequency of TA in the studied population was 4.8% (n=56). The most commonly absent tooth was the lower second premolar, followed by the upper lateral incisor. Male:female ratios varied from 2:1 in the agenesis of upper lateral incisors to 0.5:1 in lower second premolar agenesis. The frequency of ST was 2.3% (n=27). The most commonly morphology variation was the conical type (n=15) followed by the tuberculated type (n=6). The most commonly affected region was the incisive region followed by the premolar region. Male:female ratios varied from 8:1 in the conical morphology of mesiodens to 0.25:1 for the incisiform morphology of premaxilla ST. No statistically significant differences in the frequency of both dental anomalies based on gender and arch (upper versus lower; p=0.5) were found. For TA, nineteen subjects had maxillary missing teeth, 28 subjects had mandibular missing teeth, and nine subjects had tooth agenesis in both arches (p=0.1). For ST, 21 subjects had maxillary ST, six cases had mandibular ST, and no cases presented concomitant maxillary and mandidular ST (p=0.00004).

Conclusion: Our results suggest that different male:female ratios for specific patterns of dental anomalies of number exist. This finding may indicate that specific genetic factors are differentially expressed depending on gender.