Wichit Tharanon

Accuracy of face-bow transfer: Effect on surgical prediction and postsurgical result

One of the most common errors in model surgery for orthognathic surgery is in the mounting of the models on the articulator. This study assessed the ability of one type of face-bow to transfer the maxillary model to the articulator. Twenty-five consecutive mountings were evaluated by calculating the angle made between the maxillary occlusal plane on the cephalogram and comparing it with the maxillary occlusal plane angle on the articulator. An accurate face-bow transfer should transfer this angle, making the two similar. It was found that a significant difference between the maxillary occlusal plane angle on the cephalogram and the articulator was found in the average case. The implications of such errors and a technique to avoid them are presented.

Surgical outcomes using bioabsorbable plating systems in pediatric craniofacial surgery

The purpose of this study was to evaluate the surgical outcomes of the 1.5-mm LactoSorb plating system (Walter Lorenz Surgical, Inc., Jacksonville, FL, U. S. A.) used to stabilize the osteotomized calvarial bone in pediatric patients who have undergone craniofacial surgery. The records of 33 consecutive pediatric patients who underwent craniofacial surgery from January 1997 through December 1997 were reviewed. There were 18 male and 15 female patients, and the age ranged from 4 months to 12 years. Patients were followed-up at 1 week, 1 month, 3 months, 6 months, and 12 months after surgery. For those patients reviewed, the following information is included: age, sex, diagnosis, surgical procedures, number and size of LactoSorb plates and screws used in each patient, operative difficulty of the screws and the heat pack, and postoperative complications, including wound healing, palpability, and infection. The LactoSorb plating system was used to stabilize the osteotomized calvarial bones in 33 patients who were diagnosed with: 1) craniosynostosis, 2) hydrocephalus, 3) fibrous dysplasia, or 4) cranial deformation. Orbital rim advancement and anterior cranial vault reshaping were performed in 17 patients. Posterior cranial vault reshaping, orbital rim advancement, and anterior cranial vault reshaping were performed in eight patients. Posterior cranial vault reshaping only was performed in seven patients. Excision of fibrous dysplasia from temporal bone was performed in one patient. One patient had a postoperative wound infection, and LactoSorb plates were palpable postoperatively in four patients. The LactoSorb plating system provided adequate rigidity for stabilizing the osteotomized calvarial bone during surgery and maintained adequate rigidity after surgery during the bone healing period before absorption. This plating system showed satisfactory results in pediatric craniofacial surgery patients.

Comparison between the rigidity of bicortical screws and a miniplate for fixation of a mandibular setback after a simulated bilateral sagittal split osteotomy

PURPOSE This investigation compared the biomechanical stability of three bicortical screws with that of a single four-hole miniplate after 5-mm mandibular setback after a bilateral sagittal split osteotomy (BSSO) in cadaver mandibles. MATERIALS AND METHODS Thirty human cadaver hemimandibles underwent BSSO followed by two different rigid fixation techniques. All specimens had no third molar, bony pathology, or evidence of mandibular fracture, and there was no history of renal disease or hyperparathyroidism. The specimens were randomly divided into two groups. In group I, three bicortical screws were placed at the superior border, and in group II, one four-hole miniplate was secured on the external oblique ridge with four monocortical screws. The bony height of the mandible was recorded. Maximum resistance load (MRL), the greatest load recorded just before a sudden decrease in load level (bone or fixation failure), was recorded when the mandibles were tested in a compression machine. Multiple regression analysis was used to evaluate the differences in bone height and the MRL between groups I and II. RESULTS The mean bone height in groups I and II were 28.64 +/- 2.50 mm and 28.72 +/- 4.08 mm, respectively. The mean MRL in group I (20.49 +/- 7.22 kg) was greater than in group II (17.41 +/- 7.81 kg). The multiple regression analysis showed no significant difference in the bone height and the MRL between group I and group II (beta = 2.3492, P = .4114). CONCLUSION There was no statistically significant difference in stability provided the two techniques.

Transoral maxillary distraction osteogenesis of an unrepaired bilateral alveolar cleft.

Distraction osteogenesis has gained acceptance as a viable modality for lengthening hypoplastic skeletal structures in the maxillofacial region. A case of the application of this technique to advance the maxilla in an unrepaired bilateral alveolar cleft via a transoral approach is presented. The distraction devices were applied bilaterally to the zygomatic buttress region with the activating arms protruding from the oral cavity. A high Le Fort I osteotomy was performed under general anesthesia and, prior to distraction, the three maxillary segments were unified with an occlusal acrylic splint. Activation was begun 6 days after placement, at a rate of 1 mm per day, until the planned maxillary advancement had been achieved. An 8-week period of consolidation was allowed prior to removal of the devices.

Surgical correction of an aural-temporomandibular joint fistula with a temporalis flap

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A Comparative Study of Scalp Tension with and without Intraoral Subperiosteal Release of the Midface in Laser-Assisted Endoscopic Browlift

Introduction: Since the introduction of the endoscopic browlift, several techniques have been advocated to improve long-term stability and results. These include extensive undermining of the flap, muscle plication, and a variety of fixation techniques. At our institution, intraoral subperiosteal dissection is used in combination with the laser-assisted endoscopic browlift. No clinical studies have compared flap tension using the different methods of periosteal release. The purpose of this study was to compare scalp tension when the flap was pulled posteriorly 10 mm and 15 mm with and without intraoral subperiosteal release of the midface. Materials and Methods: This study included 37 patients and consisted of 4 men and 33 women. They underwent a laser-assisted endoscopic browlift with general anesthesia or intravenous sedation. Scalp tension was measured with a spring scale. Scalp tension was measured at 6 locations (the incisions over the right and left medial brows, brow heights, and temporal regions). After the laser-assisted endoscopic browlift, measurement of scalp tension at each location was recorded while the scalp was pulled posteriorly 10 mm and then 15 mm. Tensions were measured prior to and after intraoral subperiosteal release of the midface. Tensions at each incision site before and after subperiosteal release were compared using paired t tests. Tensions between the medial brow, brow height and temporal flaps for each side were also compared using paired t tests. Results: Subperiosteal release of the midface significantly reduced tension at every incision site by more than 200 g. The average amount of tension reduction gradually increased from the midline sites to the temporal sites prior to subperiosteal release of the midface. Tension was reduced by more than 300 g at the temporal sites after subperiosteal release of the midface. Conclusions: This study demonstrates that by including intraoral broad subperiosteal detachment of the midface, there is less tension on the flap at all incision sites. Reduced tension and more equally distributed tension would be expected to contribute to better would healing, improved predictability, and assumed longevity of results.

Craniofacial Deformities: Introduction and Principles of Management

In the last several years the arena of craniomaxillofacial surgery has expanded in scope, and the treatment of these deformities has become more sophisticated. In view of these many changes, the embryology, etiology, pathogenesis, imaging, and treatment of the common craniofacial deformities will be reviewed with their management.