It has been evident from the literature that the reports of response of the lower lip and soft tissue chin to the surgical advancement of the deficient lower jaw are strongly discrepant. Therefore, the objective of this study was to improve the understanding of the soft tissue response, with particular reference to the role of the preoperative soft tissue thickness. It has become evident from a review of current studies that tissue thickness may not play as significant a role as was previously thought, thus indicating the role of other factors in the prediction of the lower lip and chin response for the individual. This study assessed the soft tissue changes of the lower lip within a homogenous sample group of 39 patients who had undergone a surgical advancement of the lower jaw. Lateral cephalometric radiographic records at time periods before and after the surgical procedure were used. The radiographs were hand traced and specific landmarks were computer digitized with the Analysis System (Olympus Pty, Ltd) relative to a constructed X-Y axis. The change in the position of these landmarks at the various time periods was calculated according to the mean value of each reading for each landmark. Multiple regression analyses of the data resulted in poor correlations of the lower lip position with the extent of mandibular advancement surgery when the variables of horizontal overjet and the vertical overbite of the incisors, the lower lip thickness (lower incisor tip to labrale inferius as well as lower lip protrusion ahead of the upper incisor teeth) and the pre-operative soft tissue thickness were included (0.27 in the horizontal dimension; 0.51 in the vertical dimension). The addition of the variables tissue thickness and lower lip thickness within the multiple regression equation did not result in a notable improvement in coefficients of correlation either (0.77 to 0.78). Within the stepwise regression equations specific variables have been identified as having an influence on the prediction of the response of the lower lip and chin consequent to the mandibular advancement surgery (R2=0.93-0.97(horizontal); R2=0.89-0.96(vertical)). These points include stomion, upper incisor tip, hard and soft tissue pogonion, lower incisor tip, gnathion and menton. The prediction equations were independently cross-validated against each individual within the sample group, achieving high cross-correlation values (0.85-vertical to 0.90- horizontal) between the prediction equation and the observed values. The findings of this study have identified factors that play a role in the soft tissue response of the lower lip and chin consequent to mandibular advancement surgery, enabling a more accurate prediction for the individual.

Department of Maxillofacial and Oral Surgery, 2013 / One of the goals during surgical repositioning of the mandible is to ensure a correct condyle-fossa relationship and to maintain the position of the proximal segment at the time of placement of rigid fixation. During setback procedures, accurate control of the proximal segment is influenced by the medial pterygoid muscle and stylomandibular ligament. These structures are therefore stripped from the medial surface of the mandibular angle during surgery. The aim of this study was to investigate the influence of the muscle attachment on proximal segment control in mandibular advancement surgery. Clockwise or counterclockwise rotations of the proximal segment during surgery of two groups of patients were compared. In one group, the medial pterygoid muscle was stripped during surgery while in the other group the medial pterygoid muscle was left attached. The second group formed part of the historical development phase of the surgical technique for mandibular advancement procedures.

Submitted in partial fulfillment of the requirements for the degree of Master in the Science of Dentistry, in the department of Oral and Maxillofacial Surgery, at the University of the Witwatersrand, Johannesburg. / The correction of most skeletal class II mandibular deficient cases require the surgical advancement of the mandible for the treatment of the malocclusion. Often genioplasty is included to the procedure to improve the soft tissue profile.2,30 Long term skeletal stability is an important goal for the surgeon and orthodontist following Bilateral Sagittal Split Osteotomy (BSSO) and is influenced by the muscles attached to the mandible. Following the surgical advancement of the mandible the suprahyoid muscle complex is certainly stretched and even more so when the procedure is combined with surgical advancement of the chin.10,11 This retrospective comparative study determined the long term skeletal stability of 29 patients, whom had undergone surgical advancement of the mandible by means of BSSO with advancement genioplasty, compared to 29 patients whom had undergone mandibular advancement surgery (BSSO) without advancement genioplasty. All the subjects were evaluated using pre-operative (T1), 1 week post-operative (T2) and at least 6 months (T3) follow-up cephalometric radiographs. This research report concluded that the post-operative hard tissue relapse following BSSO advancement, with or without genioplasty, was clinically insignificant.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

Thesis (M.S.)--University of Michigan, 1976. / Typescript (photocopy). Includes bibliographical references (leaves 48-52). Also issued in print.

Thesis (M.S.)--University of Michigan, 1967. / Typescript (photocopy). Includes bibliographical references (leaves 53-54). Also issued in print.

Thesis (M.S.)--University of Michigan, 1978. / Typescript (photocopy). Includes bibliographical references (leaves 48-52). Also issued in print.

Thesis--Utrecht. / Summary in Dutch. Vita. Includes bibliographical references (p. 105-115).

Thesis (M.S.)--University of Michigan, 1978. / Typescript (photocopy). eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 48-52).

Thesis (M.S.)--University of Michigan, 1976. / Typescript (photocopy). eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 48-52).