Overbite Depth Indicator (ODI) Values in a Nigerian Population of Adults with Anterior Open Bite

Abstract

Background: The Overbite Depth Indicator (ODI) is defined as the angle of the A-B plane to the mandibular plane combined with the palatal plane to the Frankfort horizontal plane. It has been reputed to be a better diagnostic criterion for the presence of dental open bite than any other commonly used skeletal cephalometric measurement or ratio.
Objective: The purpose of the study was to evaluate the overbite depth indicator (ODI) in a population of Nigerian adults with anterior open bite.
Methods: A set of fifty pre-treatment cephalometric radiographs of adults (aged 18-25 years) with anterior open bites was compared to a set of fifty pre-existing cephalometric radiographs of normal persons of the same age range. The angles of the A-B plane to the mandibular plane (AB-MP angle) and the palatal plane to Frankfort horizontal plane (FH-PP angle) were measured. Arithmetic means and standard deviations were calculated for each measurement and their sum (ODI). The critical level of statistical significance was defined as p<0.05.
Results: The mean ODI was significantly reduced in anterior open bite subjects (63.13 o ± 6.71) compared to the controls, (66.85o ± 4.46).
Conclusion: The findings show that Nigerians generally have an open bite tendency. Factors contributing to the decreased ODI were significantly related to the mandible in open bite males and to the palate in the females.