Post-orthodontic cephalometric variations in bimaxillary protrusion cases managed by premolar extraction - A retrospective study.

Abstract

Bimaxillary protrusion is a common dentofacial condition associated with proclination of maxillary and mandibular incisors in relation to the dental and cranial bases resulting in soft tissue procumbency. The present retrospective study aimed to investigate dental and soft tissue profile changes using cephalometric analysis to evaluate bimaxillary protrusion patients after extraction of the first four premolars and subsequent retraction of the anterior teeth. Pre-treatment and post-treatment cephalometric radiographs of 46 Saudi patients (16 males and 30 females), 18-30 years of age with bimaxillary protrusion, were selected based on inclusion criteria. Dental and soft tissue landmarks were traced using the Dolphin® imaging software and statistically analyzed with SPSS® 21 software. The upper and lower incisors retroclined by a mean value of 9.6° and 9.65°, respectively, and an average distance of 4.1 mm. The level of maxillary incisor exposure was reduced by approximately 1.1 mm after treatment. A mean increase of 6.6° in the nasolabial angle was also observed. Multiple regression analysis showed that retraction of both upper and lower incisors by 1 mm would result in a 0.44 mm retraction of the upper and lower lips. A statistically significant increase in the nasolabial angle and upper lip length was found in relation to upper and lower incisor retraction and retroclination. A significant reduction was also evident in the post treatment upper incisor exposure, facial convexity angle and mentolabial sulcus depth.