Prevalence and Distribution of Sagittal and Vertical Subtypes in Skeletal Class III Malocclusion: A Retrospective Study across Age and Sex Groups

Abstract

Background: Skeletal Class III malocclusion causing mandibular prognathism, maxillary retrognathism, or a combination of both, has widely varying prevalence by ethnicity. The objective of this research is to investigate the prevalence of contributing factors in its development across different age and sex groups of Iranians. Materials and Methods: In this study, 233 lateral cephalograms of patients with skeletal Class III malocclusion who had referred our orthodontics center from 2015 to 2024. In the sagittal dimension, the samples were categorized into four groups: retrognathic maxilla, prognathic mandible, combination, and normal. The prevalence of each condition was analyzed across groups. In case of discrepancies between Steiner and McNamara analyses, final sagittal diagnoses were manually determined. Results: This study examined 233 lateral cephalograms of individuals with skeletal Class III malocclusion, including 101 males (43.3%) and 132 females (56.7%). There was a significant association between the final sagittal relationship diagnosis and the combined age-sex groups (P=0.010), indicating that the distribution of sagittal patterns varies across age and sex subgroups. Mandibular prognathism was the most prevalent condition in all groups except for females aged 7–11, where mandibular prognathism and maxillary retrognathism were equally common. In the vertical dimension, 51.9% of cases had normal facial height. No significant correlation was found between vertical dimension and age or sex (P=0.479). The strongest positive correlation was observed between Sum.o.p and SN.GoMe, as well as Wits and A. NPPD, while the strongest negative correlations involved Jarabak.index with Sum.o.p and SN.GoMe. Conclusion: The results indicated that mandibular prognathism is the predominant cause of skeletal Class III malocclusion, except in females aged 7–11, where maxillary retrognathism is also prevalent. No discernible pattern was detected in vertical classification among age and sex groups. The research shows the significance of employing various diagnostic methods for a thorough assessment.