Radiographic Blind Test of Curvature of the Posterior Border of the Mandibular Ramus as a Morphological Indicator of Gender

Curvature of the posterior border of the mandibular ramus at the occlusal plane has been described as a morphological trait for males. Controversy over the accuracy of this method remains among researchers; studies employing similar methods report accuracy rates for successful gender identification ranging from 59% to 99%. This blind study assessed evaluators' ability to determine gender based on the presence or absence of curvature of the posterior margin of the mandibular ramus through panoramic radiographs.

Randomly selected panoramic radiographs were obtained from The Ohio State University College of Dentistry for 413 adult male (M) and female (F) subjects. Two evaluators separately assigned ratings using a similar method to the Loth and Henenberg methodology to each subject on the right and left sides of mandibular rami. The ratings were based upon three criteria: (1) presence of curvature at the occlusal plane (M), (2) presence of curvature but not at the occlusal plane (F), and (3) lack of curvature (F). Pearson exact chi-squared test was used to evaluate the statistical strength of the ratings.

The evaluators were only in agreement for both the right and left rami in roughly two-thirds (66.8%) of cases when there was no excessive tooth loss (ETL); however, the inter-observer agreement improved to 82.1% for those rami associated with ETL. Inter-observer agreement occurred in 72.9% of female rami and in only 64.4% of male rami.

The results of this study indicated that assessment of posterior border curvature of  mandibular rami through panoramic radiographs was not a reliable indicator of gender and was further plagued by unacceptably high levels of inter-observer disagreement.