Ponticulus posticus: Anatomical Variation in Posterior Arch of the Atlas Vertebra Evaluated in Lateral Cephalometric Radiography

Aims: To evaluate the prevalence of the Ponticulus posticus in a Brazilian sample and discuss about the importance of this anatomical variation in forensic dentistry area.

Study Design: Observational and transversal study.

Place and Duration of Study: Department of Morphology, Anatomy division, Piracicaba Dental School, University of Campinas-UNICAMP, between June 2014 and December 2015.

Methodology: We used 242 lateral cephalometric radiographs of adult individual skulls from both sexes (from 18-60 years old). The sample was divided into the following groups: 92 lateral radiographs of males, and 150 lateral radiographs of females. The visual assessment method was performed by the same examiner. Classification form was carried out in three categories in both sexes: Presence of Ponticulus posticus with complete ossification; presence of Ponticulus posticus with incomplete ossification and absence. Data were performed a descriptive analysis by a decision tree. The sample data were segmented by sex, posteriorly by the presence of Ponticulus posticus, and then as complete or incomplete. Also were applied chi square test to analyze the correlation between the presence or absent of the Ponticulus posticus in relation about sex and the correlation about the Ponticulus posticus is complete or incomplete. The significant level was adjusted to 5%.

Results: From the total sample of 242 individuals, 92 (38.02%) were male sex and 150 (61.98%) were female sex. Among the male ones, 19 (7.85%) had shown Ponticulus posticus with 10 (4.13%) of them presenting incomplete foramen ossification and the other 9 (3.72%) presenting complete foramen ossification. Concerning the females ones, 34 (14.05%) exhibited this anatomical variation, being 21(8.68%) incomplete and 13 (5.37%). In general, there was no sex influence (chi-square, p = 0.8354399) in the presence of Ponticulus posticus, indicating that sex is not an influence factor.

Conclusion: The presence of this anatomical variation cannot be related to sexual dimorphism.