Critical Analysis of Piezoelectric Surgery with Oscillating Saw in Bimaxillary Orthognathic Surgery

OBJECTIVE

To compare the piezosurgery with conventional saw for osteotomy in orthognathic bimaxillary surgery.

STUDY DESIGN

Comparative study.

PLACE AND DURATION OF STUDY

The Armed Forces Institute of Dentistry, Rawalpindi, Pakistan, from January 2012 to July 2015.

METHODOLOGY

Twenty-four patients, regardless of gender, were selected for bimaxillary surgery. Each underwent osteotomy with conventional saw and piezosurgery equipment. Intraoperative and postoperative parameters, like blood loss during operation, time required for surgery, postoperative swelling, nerve function, incision and surgical precisons, were evaluated.

RESULTS

Out of total 96 osteotomies, 48 (50%) maxillary and 48 (50%) mandibular osteotomies were performed. Time required for piezosurgery was more (63 minutes) as compared to saw (p=0.003). Other parameters, like intraoperative blood loss (p=0.091), postoperative swelling (p=0.041), and nerve damage (p=0.009), were far less frequent with piezosurgery than frequent with saw procedures.

CONCLUSION

Piezosurgery is a favourable alternative technique as compared to saw technique in bimaxillary orthognathic surgeries.

Bad splits in bilateral sagittal split osteotomy: systematic review of fracture patterns

An unfavourable and unanticipated pattern of the mandibular sagittal split osteotomy is generally referred to as a 'bad split'. Few restorative techniques to manage the situation have been described. In this article, a classification of reported bad split pattern types is proposed and appropriate salvage procedures to manage the different types of undesired fracture are presented. A systematic review was undertaken, yielding a total of 33 studies published between 1971 and 2015. These reported a total of 458 cases of bad splits among 19,527 sagittal ramus osteotomies in 10,271 patients. The total reported incidence of bad split was 2.3% of sagittal splits. The most frequently encountered were buccal plate fractures of the proximal segment (types 1A-F) and lingual fractures of the distal segment (types 2A and 2B). Coronoid fractures (type 3) and condylar neck fractures (type 4) have seldom been reported. The various types of bad split may require different salvage approaches.

Accuracy of three-dimensional soft tissue simulation in bimaxillary osteotomies

The purpose of this study was to evaluate the accuracy of an algorithm based on the mass tensor model (MTM) for computerized 3D simulation of soft-tissue changes following bimaxillary osteotomy, and to identify patient and surgery-related factors that may affect the accuracy of the simulation. Sixty patients (mean age 26.0 years) who had undergone bimaxillary osteotomy, participated in this study. Cone beam CT scans were acquired pre- and one year postoperatively. The 3D rendered pre- and postoperative scans were matched. The maxilla and mandible were segmented and aligned to the postoperative position. 3D distance maps and cephalometric analyses were used to quantify the simulation error. The mean absolute error between the 3D simulation and the actual postoperative facial profile was 0.81 ± 0.22 mm for the face as a whole. The accuracy of the simulation (average absolute error ≤2 mm) for the whole face and for the upper lip, lower lip and chin subregions were 100%, 93%, 90% and 95%, respectively. The predictability was correlated with the magnitude of the maxillary and mandibular advancement, age and V-Y closure. It was concluded that the MTM-based soft tissue simulation for bimaxillary surgery was accurate for clinical use, though patients should be informed of possible variation in the predicted lip position.

Risk factors and prevention of bad splits during sagittal split osteotomy

PURPOSE

One of the operative complications of the sagittal split osteotomy of the mandible is a bad split, which describes an unfavorable or irregular fracture of the mandible in the course of the osteotomy. The purpose of this study is to identify previous studies which reported incidences of bad split occurrence during sagittal split osteotomy and to discuss its mechanisms and risk factors, based on a literature review, in order to minimize their occurrence. A few illustrative cases are also presented.

METHODS

An electronic search was undertaken in January 2011. The titles and abstracts from these results (n = 363) were read for identifying studies which reported incidences of bad split occurrence during sagittal split osteotomy procedures.

RESULTS

Twenty-one studies were identified and assessed. The incidence of bad splits from these studies varied between 0.21% and 22.72%. The buccal plate of the proximal segment and the posterior aspect of the distal segment were the most affected areas.

DISCUSSION

The surgical patient should be evaluated according to age and the presence of unerupted/impacted third molars. Prevention is focused on adequate osteotomy design, eliminating sharp angle where abnormal stress occurs on bony segments, completion of adequate cuts into the retrolingular depression and through the inferior border, and careful separation of the segments. The SSO is an extremely technical and sensitive procedure, and careful attention will probably prevent most unfavorable splits. If a fracture occurs, the fractured segments should be incorporated into the fixation scheme if possible. The occurrence of bad splits cannot always be avoided. When adequately treated the chances of functional success are good.