Does high gonial angle increases the risk of mandibular angle fracture? A digital orthopantomographic study.

Abstract

Fracture of mandibular angle comprises up to one third of mandibular fractures. Many local anatomical factors may increase the risk of such fractures. This study was conducted to investigate the risk of angle fractures with gonial angle measurements. A retrospective cross-sectional study was conducted on digital panoramic radiographs of 120 patients with isolated mandibular fractures. The patients were categorized into mandibular angle and other nonangle fracture groups. The gonial angle, antegoneal angle, ramus height was measured using Image J software. Out of 120 isolated mandibular fractures, 40 (33.33%) are angle fractures and 80 (66 .67%) are other nonangle isolated fractures. Seventy- five percent of angle fractures and 85% of non-angle fractures occurred in males. The average age of angle fracture patients was 28.34±5.2 years and 27.37 ±4.9 years for the non-angle fractures with no significant difference (p=0.31). The gonial angle of the angle fractures was 127.60 º ±4.93 º which is 6 degrees greater than the non-angle fractures. The antegonial angle of the angle fractures was 160.67±5.38º which is 5.2 º less than the non-angle fractures. The ramus height in the angle fractures was 18.97±3.7 mm which is 2.5 mm shorter than the nonangle fractures. The difference in these three measurements was highly significant (p<0.0001). About 45% of angle fractures and 19% of non-angle fractures occurred in the high gonial angle. The presence of high mandibular angle doubles the risk of mandibular angle fracture. Key words:Angle fracture, gonial angle, Image J, mandiblular fractures, orthopantomograph.