A nonradiographic approach to detect Class III skeletal discrepancies.

INTRODUCTION

Because of the hereditary nature of Class III malocclusion, relatives of affected subjects often ask for a consultation. To estimate the degree of skeletal manifestation without exposing them to radiation, an alternative to lateral cephalograms would be valuable for preliminary diagnosis. Thus, we aimed to assess the validity of profile photographs to detect skeletal Class III discrepancy.

METHODS

Profile photographs and lateral cephalograms were available from 42 young white men, 29 with Class III malocclusion and 13 with Class I. A computer-based analysis was performed including hard-tissue variables on cephalograms and soft-tissue variables on photographs

RESULTS

Soft-tissue facial characteristics showed strong correlations with several skeletal structures of skeletal Class III subjects (r > or = 0.7, P < 0.001). Thus, soft-tissue A'N'B', A'N'Pog', and N'A'/A'Pog' were highly related to skeletal ANB, ANPog, and NA/APog. Vertically, soft- and hard-tissue lower anterior face heights were strongly correlated. A soft-tissue A'N'B' angle of 6 degrees is the critical value below which skeletal Class III can be implied (sensitivity, 90.5%; specificity, 81.0%). This finding was validated among female subjects.

CONCLUSIONS

A profile photograph can show with high probability a skeletal Class III discrepancy and might be useful for diagnosis during the initial consultation.