Submandibular soft tissue changes after mandibular set-back surgery in skeletal Class III patients.

PURPOSE: To investigate the submandibular soft tissue changes related to the hard tissue changes after mandibular set-back surgery in skeletal Class III patients. METHODS: The subjects were adults with skeletal Class III malocclusion who underwent orthognathic surgery including mandibular set-back between June 2007 and January 2011 at Kyung Hee University Dental Hospital at Gandong. Standardized lateral cephalograms that were taken before and 6 to 12 months after surgery were collected. Sixty samples were selected. Each lateral cephalograms was traced and lines, angles and areas associated with submandibular soft tissues were measured and analyzed statistically. RESULTS: Anteroposterior submandibular soft tissue length was reduced with reduction of mandibular body length. FH to mandibular plane angle was decreased and FH to submandibular line angle was increased. A gender difference was found in soft tissue changes. Males showed altered vertical soft tissue thickness and submandibular tissue area reduction after surgery. Several hard tissue changes were correlated with soft tissue changes and through multiple regression models with stepwise selection method, several regression equation models to predict soft tissue changes related to hard tissue changes were made. CONCLUSION: After orthognathic surgery including mandibular set-back, the submandibular soft tissue profile changes. Equations to predict submandibular soft tissue changes after mandibular set-back surgery were developed.

The influence of bilateral sagittal split ramus osteotomy on submental-cervical aesthetics.

The effect of orthodontic-surgical treatment on submental-cervical region was evaluated in a very limited number of studies. The aim of this study was to evaluate submental-cervical soft tissue contour changes following mandibular advancement and set-back procedures via bilateral sagittal split ramus osteotomy. Sixty-seven patients were included in this study. Group 1 consisted of 27 skeletal Class II patients who underwent mandibular advancement surgery, whereas Group 2 consisted of 40 skeletal Class III patients who underwent mandibular set-back surgery. Various linear and angular measurements were performed on pre-operative and sixth month post-operative cephalometric radiographs. A new method was used to evaluate the amount of sagging at submental region. The submental length did not change in Group 1; however, it decreased significantly in Group 2 (P < 0·05). The angle between submental plane and facial plane decreased to 95·9° from 98·8° in Group 1(P < 0·05), whereas it increased to 93·1° from 88·2° in Group2 (P < 0·05). The change of submental soft tissue sag was almost stable in Group 1, while 0·34 mm increase of sag was observed in Group 2. This increase was not statistically significant (P > 0·05). Mandibular set-back and advancement procedures do not remarkably change the submental sag following approximately 6 mm jaw movement. Although mandibular advancement did not significantly effect submental length, soft tissue followed mandibular set-back with a ratio of 1:1 at C-point to projection of soft tissue pogonion and 1:0·7 at C-point to soft tissue menton distances.

Prediction of Amount of Mandibular Set Back with 3 Plain Radiographs in Mandibular Sagittal Split Ramus Osteotomy

Clinical analysis of early reoperation cases after orthognathic surgery

The factors influencing the relapse and recurrence of skeletal deformity after the orthognathic surgery include various factors such as condylar deviation, the amount of mandibular set-back, stretching force by the soft tissues and muscles around the facial skeleton. The purpose of this report is to recognize and analyze the possible factors of reoperation after orthognathic surgery, due to early relapses. Six patients underwent reoperation after the orthognathic surgeries out of 110 patients from 2006 to 2009 were included in this study. In most cases, clincal signs of the insufficient occlusal stability, anterior open bite, and unilateral shifting of the mandible were founded within 2 weeks postoperatively. Although elastic traction was initiated in every case, inadequate correction made reoperation for these cases inevitable. The chief complaints of five cases were the protruded mandible combined with some degree of asymmetric face and in the other one case, it was asymmetric face only. Various factors were considered as a major cause of post-operative instability such as condylar sagging, counter-clockwise rotation of the mandibular segment, soft tissue tension related with asymmetrical mandibular set-back, preoperatively existing temporomandibular disorder (TMD), poor fabrication of the final wafer, and dual bite tendency of the patients.

Accuracy of soft tissue profile change prediction in mandibular set-back surgery patients: a comparison of Quick Ceph Image Pro(TM) (ver 3.0) and V-Ceph(TM) (ver 3.5) / 대한치과교정학회지

The purpose of this study was to test and compare the accuracy and reliability of soft tissue profile predictions generated from two computer software programs (Quick Ceph Image Pro(TM) (ver 3.0) and V-Ceph(TM) (ver 3.5)) for mandibular set-back surgery. The presurgical and postsurgical lateral cephalograms of 40 patients (20 males and 20 females) were traced on the same acetate paper with the reference taken as the cranial base outline. The presurgical skeletal outlines were digitized onto each computer program and the mandible was moved to mimic the expected surgical procedure with reference to the mandibular anterior border and lower incisor position of the actual postsurgical skeletal outline. The soft tissue profile was generated and the amount and direction of skeletal movement was calculated with each software. The predicted soft tissue profile was compared to the actual postsurgical soft tissue profile. There were differences between the actual and the predicted surgical soft tissue profile changes in the magnitude and direction, especially the upper lip, lower lip and the soft tissue chin (p < 0.05). Quick Ceph had more horizontal measurement errors and thickness errors for the upper lip and lower lip, but V-Ceph had more vertical measurement errors of the lower lip (p < 0.05). There was a positive correlation between the prediction errors and the amount of mandibular movements in the vertical position of Sn, the horizontal position of Ls and the upper lip thickness for V-Ceph, and there was a negative correlation in the horizontal position and the thickness of the lower lip for Quick Ceph (p < 0.05). However, all of the prediction errors of both imaging softwares were ranged within 3 mm, and this was considered to be allowable clinically.