Evaluation of correlation between mesio-distal width of permanent incisors and arch width in a sample of Sri Lankan population

Objective: This study examines the correlation between incisor width (IW) and arch width (AW) within the Sri Lankan population to establish population-specific dental parametric standards, thereby enhancing the fields of forensic odontology and evidence-based clinical dentistry.
Materials and Methods: A cross-sectional study was conducted to investigate a hypothesized correlation between the mesio-distal width (MD) of permanent incisors and arch width (AW), aiming to examine this relationship and assess sexual dimorphism in incisor width (IW), involving individuals aged 18 to 30 years, representing both sexes, with casts selected through random sampling. Measurements of maxillary and mandibular incisors, inter-canine, and inter-molar widths were taken using a digital vernier calliper, with each measurement triplicated. Pearson correlation coefficient and t-test were performed for statistical analysis.
Results: A statistically significant correlation was observed among all upper arch dimensions (p<0.05), except for the average AW of the upper inter-molar region and average MD of the upper left lateral incisor (21). Lower AW significantly correlated with MD of lower incisors (p<0.0001). Males showed statistically higher IW mean values (p<0.05) than females, with the only exceptions being upper right (12) and left (22) lateral and lower left central incisors. IW and AW showed a significant correlation (p<0.05) in both arches for both sexes, with few exceptions. No significant correlation was found between the upper inter-molar width and the MD of 12, 21, and 22 in males. In females, the same lack of correlation was noted for 22 and lower right lateral incisors with respective inter-molar widths.
Conclusion: The findings suggest that the inter-canine AW may be the most reliable dimension predictable from the MD of incisors for both sexes and vice versa. The study also confirms sexual dimorphism in incisor size, with males exhibiting significantly larger MD values, with few exceptions. Future investigations into different populations would broaden the understanding of these relationships.