Cephalometric characteristics and dentoalveolar compensation across skeletal malocclusionsin a Nigerian orthodontic population: a retrospective cross-sectional study

Objectives: Cephalometric characteristics of malocclusion and accompanying dentoalveolar compensation are population specific and remain incompletely described in Nigerian orthodontic patients. This study compared Angle’s Molar Relationship and Skeletal Pattern, two related but non-interchangeable classification systems, and characterised cephalometric measurements, dentoalveolar compensation, and clinical presentation across Classes I, II, and III under each. Methods: This retrospective cross-sectional study included 219 orthodontic patients classified by Angle's Molar Relationship (primary) and Skeletal Pattern (secondary). Sagittal, vertical and dental cephalometric measurements were compared across classes using the Kruskal-Wallis test with Dunn post-hoc comparisons (Benjamini-Hochberg adjusted). Upper incisor inclination, lower incisor inclination (IMPA) and the interincisal angle were modelled by multivariable linear regression on both classifications, adjusted for age, sex, vertical pattern and overjet. Results: By Angle's Molar Relationship, Class I predominated (158; 72%), followed by Class II (42; 19%) and Class III (19; 9%).By Skeletal Pattern, Class II predominated (129; 58.9%), followed by Class I (56; 25.6%) and Class III (34; 15.5%). The two systems agreed in only 42.9% of patients. Under Angle's classification, ANB, SNB, SNA, LAFH, IMPA, interincisal angle and overjet differed significantly across classes (all p ≤ 0.025). Angle's Class III remained independently associated with a more retroclined lower incisor (IMPA β = −5.79°, 95% CI −9.51 to −2.07, p = 0.002) and a larger interincisal angle (β +5.55°, p =0.036), whereas no Skeletal Pattern class was independently associated with either outcome. Skeletal Pattern Class II was associated with a less proclined upper incisor (U1–Frankfort β = −3.32°, p = 0.007). Crossbite differed significantly across Angle classes (68% of Class III, 24% of Class II, 32% of Class I; p = 0.002). Conclusions: The predominant class depended on the classification used: Class I by Angle's Molar Relationship and Class II by Skeletal Pattern, with agreement in fewer than half of the patients. Lower-incisor compensation in Class III tracked the occlusal classification more closely than the skeletal one, though a formal test of the difference was not performed. These findings suggest that the classification system used should always be stated explicitly. Keywords: cephalometry; skeletal malocclusion; ANB angle; dentoalveolar compensation; Nigeria; orthodontics Abbreviations: ANB: A point–nasion–B point angle; FMA: Frankfort–mandibular plane angle; IIA: interincisal angle; IMPA:incisor mandibular plane angle (L1–mandibular plane); LAFH: lower anterior face height; MMA: maxillary–mandibular plane angle; SNA: sella–nasion–A point angle; SNB: sella–nasion–B point angle; U1: upper central incisor; L1: lower central incisor.