Dental Arch Dimensions among Orthodontic Patients: A Retrospective Study in a Nigerian Teaching Hospital

Abstract

Aims: To evaluate dental arch width dimensions among orthodontic patients treated at a Nigerian teaching hospital and to assess differences between maxillary and mandibular arches, as well as variations related to gender and age. Study Design: Retrospective Study. Place and Duration of Study: Department of Child Dental Health (Orthodontic Unit), University of Port Harcourt Teaching Hospital, between January 2021 and December 2025. Methodology: Pre-treatment orthodontic study models of 120 patients were analysed. Measurements of maxillary and mandibular intermolar widths (between mesiopalatal/mesiolingual cusps of first permanent molars), maxillary and mandibular intercanine widths (between canine cusp tips), palatal length (from incisive papilla centre to midpoint between first molars), and vertical distance of the anterior palatal midline (APM) were recorded. Data were analysed using IBM SPSS version 26. Descriptive statistics (frequencies and percentages) were generated. Paired-sample t-tests compared maxillary and mandibular dimensions, while one-way multivariate analysis of variance (MANOVA) assessed gender and age-related differences. Statistical significance was set at p < 0.05. Results: For the 120 pre-orthodontic study models (49 males [40.8%], 71 females [59.2%]), maxillary intermolar width was significantly greater than mandibular intermolar width (4.34 ± 0.38 cm vs. 3.92 ± 0.45 cm; p < .001). Similarly, maxillary intercanine width was significantly greater than mandibular intercanine width (3.85 ± 0.49 cm vs. 3.17 ± 0.46 cm; p < .001). Palatal length was significantly greater than the vertical palatal dimension (3.21 ± 0.56 cm vs. 2.68 ± 0.51 cm; p < .001). A significant gender difference was observed only for mandibular intermolar width, with males demonstrating higher values than females (p = 0.03). No statistically significant differences in dental arch width dimensions were observed across age groups. MANOVA revealed no significant overall effects of gender (λ = 1.421, p = 0.213) or age (λ = 1.319, p = 0.173) on dental arch width dimensions. Conclusion: Orthodontic patients in this Nigerian population demonstrated a consistent transverse relationship characterised by wider maxillary than mandibular arch dimensions. Gender and age had minimal effect on dental arch width dimensions.