Determination of normal maxillary transverse dimension by using intercanine width and interpalatal first molar width.

BACKGROUND: Malocclusion in the vertical and sagittal planes is easy to observe whereas it is difficult to diagnose malocclusion in the transverse plane. There are yet no criteria defining a normal transverse occlusion.

AIM: The aim of this study was to identify a ratio that defines a normal transverse occlusion.

STUDY DESIGN: This was a retrospective study.

MATERIALS AND METHODS: A total sample of 151 maxillary dental models (M = 55, F = 96) in the age range of 12-16 years were randomly selected, with 73 models in control group and 78 in the study group. All the models were mixed up and given to an operator for the measurement of intercanine width (ICW) and inter-palatal molar width (IPMW).

STATISTICAL ANALYSIS USED: The data were statistically analyzed using SPSS software version 16.0. Chi-square test was performed to test the statistical significance difference between the groups at p ≤ 0.05.

RESULTS: Nearly 98.60% of normal arches were found to have an IPMW to ICW ratio of 1:1 ± 0.05. On further analysis, it was found that when IPMW ≥37.45 mm, then the case may be considered to have normal arches, and if the ratio between IPMW to ICW is 1.15:1 ± 0.05 or more and IPMW is <34.92 mm, then the case may be identified as deficient arch.

CONCLUSION: The IPMW-to-ICW ratio can be used to differentiate deficient and normal arches. This hypothesis (Banker's hypothesis) is an easy and noninvasive method, using only two parameters, developed to help clinicians in identifying normal transverse dimension.