Panoramic radiographs: determination of mandibular steepness.

The aim of this study was to evaluate the potential of panoramic radiographs to measure mandibular inclination and steepness. Standardized panoramic and lateral cephalometric radiographs were taken for 95 subjects (46 females, mean age 12.4 +/- 1.2 years; 49 males, mean age 12.1 +/- 1.3 years). Mandibular inclination from panoramic radiograph was measured using gonial angle formed by the tangents of the lower border of the mandible and the distal border of the ascending ramus and the condyle. A correlation test was performed to check for similarity between the measurements. The mean values for the gonial angle were 127.3 +/- 6.2 and 125.7 +/- 6.5 degrees measured from the panoramic and cephalometric radiographs respectively. A high correlation between the measurements taken from both radiographs was found (r = 0.83, P < 0.001). Panoramic radiographs are a useful tool for the measurement of gonial angle, which is an indicator of manibular steepness and subsequently mandibular growth direction. The ability to determine growth direction from the orthopantomogram will be useful because majority of dentists request an OPG for patients during routine dental examination. This will enable the dental professional to spot vertical growth problems using a readily available tool.