Total Facial Convexity Angle (G-Prn-Pg) Across Malocclusion Classes

Objectives:
Quantitative assessment of facial soft-tissue morphology constitutes a fundamental component oforthodontic diagnosis and treatment planning, providing objective information on craniofacial aesthetics andfunctional characteristics. This study aimed to systematically evaluate variations in the angle of total facialconvexity (G-Prn-Pg) among individuals exhibiting Class I, II, and III sagittal malocclusion patterns.
Methods:
A total of 30 subjects were included in the study and allocated into three groups according tomalocclusion class (Class I, II, and III). Standardized high-resolution right profile photographs were obtainedfor all participants and calibrated to ensure measurement accuracy. Photogrammetric analysis of the soft-tissue profile was performed using specialized software, and the G-Prn-Pg angle was measured for eachindividual. Intergroup differences were analyzed using one-way ANOVA followed by post-hoc Tukey tests.Mann-Whitney U tests were conducted to assess potential gender-related variations within each malocclusiongroup.
Results:
The mean value of the angle of total facial convexity (G-Prn-Pg) was 139.81° ± 3.29 in Class I,134.83° ± 4.37 in Class II, and 144.83° ± 5.64 in Class III. One-way ANOVA demonstrated a statisticallysignificant difference among the malocclusion classes (F = 12.15; p < 0.001). Post-hoc Tukey analysisrevealed a significant difference between Class II and Class III (p = 0.0001), while comparisons between ClassI and the other groups were close to the threshold of statistical significance. Slight sex-related differences inthe G-Prn-Pg angle were observed across malocclusion classes, with mean values of 140.08° in males and139.74° in females in Class I, 137.32° and 133.18° in Class II, and 142.58° and 147.08° in Class III,respectively. However, these differences were not statistically significant.
Conclusions:
The angle of total facial convexity G-Prn-Pg angle represents a useful soft-tissue parameter fordistinguishing facial profile characteristics associated with different sagittal malocclusion patterns. Sexualdimorphism appears to have a limited influence on this soft-tissue measurement, indicating that skeletalpattern rather than gender is the primary factor associated with variations in facial convexity.
KEYWORDS:
malocclusion, orthodontics, soft-tissue analysis.