The diagnostic ability of the Fränkel manoeuvre in detecting mandibular versus maxillary involvement in subjects with a class II discrepancy

Abstract

Abstract Objective This study aimed to evaluate the ability of the Fränkel manoeuvre to identify the contributing jaw to a class II malocclusion. Methods This cross-sectional study examined 37 subjects (age range 9–13 years) who presented with a class II malocclusion and an overjet greater than 6 mm. Two profile photographs were taken of each patient, one in centric relation, and the other after executing the Fränkel manoeuvre to generate a canine and molar class I relationship. The photographs were distributed to two groups of judges who included 20 general dentists and 20 orthodontists. The level of profile aesthetics before (T0) and after (T1) the manoeuvre was determined using a 100-mm visual analogue scale, and a score of “profile improvement” was determined as T1 minus T0. The diagnostic ability of the Fränkel manoeuvre was calculated against lateral cephalometry as the reference standard, using the receiver operative characteristics (ROC) analysis. Results Twenty-six subjects had mandibular retrusion and 11 showed mandibular retrusion combined with maxillary prominence. The improvement score after the manoeuvre was significantly greater in subjects who showed a one-jaw than those with a two-jaw involvement (P < 0.05). In cases that showed an improvement score ≥ 9 as judged by general dentists, or ≥ 17 as judged by orthodontists, the class II discrepancy mainly resulted from mandibular retrusion. The correspondingly lower improvement scores indicated that maxillary prognathism was involved in the class II discrepancy. Conclusion The Fränkel manoeuvre was an effective clinical method for diagnosing the contributing jaw in class II malocclusion patients.