Virtual surgical planning for orthognathic surgery using digital data transfer and an intraoral fiducial marker: the charlotte method.

PURPOSE: We describe an alternative workup protocol for virtual surgical planning of orthognathic surgery using an intraoral fiducial marker, clinical photography, and the digital transfer of occlusal data. We also discuss our initial experience using this protocol in a series of patients. PATIENTS AND METHODS: A retrospective cohort study was performed of consecutive patients who had undergone combined maxillary and mandibular osteotomies for the correction of dentofacial deformities at 1 center. These patients underwent treatment planning using the modified virtual surgical planning protocol described in the present report. The primary outcome evaluated was the accuracy of the method, which was determined through superimposition of the surgical plan to the postoperative cone-beam computed tomography (CBCT) scan. The secondary outcomes included the accuracy of the natural head position readings and the adequacy of the CBCT scanned stone models for the fabrication of occlusal splints. RESULTS: The population included 25 patients. The root mean standard deviation (RMSD) from the preoperative plan to the postoperative scan at the maxillary cephalometric points was 1.2, 1.4, and 2.1 mm in the axial, sagittal, and coronal planes, respectively. The RMSD of the superimposed plan to the postoperative scan at the 3 mandibular cephalometric points was 1.2, 0.8, and 0.7 mm in the axial, sagittal, and coronal planes, respectively. The average variance from the axial, sagittal, and coronal planes for the natural head position was 0.05, 2.22, and 0.69 mm, respectively. All splints fabricated from the CBCT occlusal data fit the stone models and were used intraoperatively. In the subset of patients whose models were both digitally transferred and laser scanned, the superimposition of the laser scan data to the CBCT scanned data was found to have a maximum variation of 0.2 mm at the occlusal level. CONCLUSIONS: The use of an intraoral fiducial marker changed the workflow for the data collection needed for virtual surgical planning of the correction of dentofacial deformities, while still obtaining accurate results. Because the device does not cause lip distortion, the possibility of virtually predicting a more expectant postoperative lip position exists without the need for additional scans. Furthermore, this work flow allows the transfer of data to be isolated to digital media.

Complications following surgically assisted rapid palatal expansion: a retrospective cohort study.

PURPOSE: To examine the prevalence of complications and characterize the associated clinical findings in patients undergoing surgically assisted rapid palatal expansion (SARPE). MATERIALS AND METHODS: A retrospective evaluation was conducted of all patients who underwent SARPE from January 2004 through December 2008 at Kaiser Permanente Oakland Medical Center. Medical records were abstracted, and demographic factors and relevant comorbidities were identified. Clinical features of patients with complications (surgical and/or dental) after SARPE were characterized. RESULTS: One hundred thirty-one patients comprised the study sample and 11 patients were excluded. Of the remaining 120 patients (median age, 29.5 yrs; interquartile range, 22.0 to 39.0 yrs), 51.7% were women, 41 developed at least 1 complication, 33 had surgical complications, 18 had dental and/or periodontal problems, and 10 developed both surgical and dental or periodontal problems. Asymmetric and/or inadequate expansion was the most frequent surgical complication, found in 13.3% of the study cohort, and gingival recession (8.3%) was the most common dental complication. Two patients developed catastrophic periodontal bone defects resulting in loss of the central incisors; these patients had eccentric interdental osteotomies that caused separation of the bone from the root surface of the central incisors followed by postoperative osteotomy site infections. CONCLUSIONS: Overall, the present findings suggest that, although major complications after SARPE were rare, asymmetric or inadequate expansion and dental and/or periodontal problems primarily involving the central incisors accounted for most complications. Future prospective and long-term follow-up studies are needed to identify individual risk factors that may predispose patients to adverse outcomes after SARPE.

Testing a better method of predicting postsurgery soft tissue response in Class II patients: A prospective study and validity assessment.

OBJECTIVE: (1) To perform a prospective study using a new set of data to test the validity of a new soft tissue prediction method developed for Class II surgery patients and (2) to propose a better validation method that can be applied to a validation study. MATERIALS AND METHODS: Subjects were composed of two subgroups: training subjects and validation subjects. Eighty Class II surgery patients provided the training data set that was used to build the prediction algorithm. The validation data set of 34 new patients was used for evaluating the prospective performance of the prediction algorithm. The validation was conducted using four validation methods: (1) simple validation and (2) fivefold, (3) 10-fold, and (4) leave-one-out cross-validation (LOO). RESULTS: The characteristics between the training and validation subjects did not differ. The multivariate partial least squares regression returned more accurate prediction results than the conventional method did. During the prospective validation, all of the cross-validation methods (fivefold, 10-fold, and LOO) demonstrated fewer prediction errors and more stable results than the simple validation method did. No significant difference was noted among the three cross-validation methods themselves. CONCLUSION: After conducting a prospective study using a new data set, this new prediction method again performed well. In addition, a cross-validation technique may be considered a better option than simple validation when constructing a prediction algorithm.

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.

Symptomatic venous thromboembolism in orthognathic surgery and distraction osteogenesis: a retrospective cohort study of 4127 patients.

Venous thromboembolism is a common postoperative complication, and orthopaedic procedures are particularly at risk. We designed a retrospective, single centre, observational, cohort study of 4127 patients (mean (SD) age 27 (11) years) who had elective orthognathic operations or distraction osteogenesis between January 1970 and February 2012 at the VU University Medical Centre, Amsterdam, to investigate the incidence in this group over the 42-year period, 2 patients developed symptomatic venous thromboembolism (1 woman had a deep vein thrombosis (DVT) and 1 man had a DVT and pulmonary embolus) postoperatively. In relatively young patients with low to moderate risk factors and short hospital stay this type of operation is associated with a particularly low risk of developing thrombosis. It could be advisable to limit the use of thromboprophylaxis to patients at high risk or according to hospital guidelines.

A better statistical method of predicting postsurgery soft tissue response in Class II patients.

OBJECTIVE: To propose a better statistical method of predicting postsurgery soft tissue response in Class II patients. MATERIALS AND METHODS: The subjects comprise 80 patients who had undergone surgical correction of severe Class II malocclusions. Using 228 predictor and 64 soft tissue response variables, we applied two multivariate methods of forming prediction equations, the conventional ordinary least squares (OLS) method and the partial least squares (PLS) method. After fitting the equation, the bias and a mean absolute prediction error were calculated. To evaluate the predictive performance of the prediction equations, a leave-one-out cross-validation method was used. RESULTS: The multivariate PLS method provided a significantly more accurate prediction than the conventional OLS method. CONCLUSION: The multivariate PLS method was more satisfactory than the OLS method in accurately predicting the soft tissue profile change after surgical correction of severe Class II malocclusions.

Longitudinal trends in discharge patterns of orthognathic surgeries: is there a regionalization of procedures in teaching hospitals?

OBJECTIVE: The aim of this study was to determine if there is regionalization of orthognathic surgeries to teaching hospitals during the study period. STUDY DESIGN: The Nationwide Inpatient Sample for years 2000-2008 was used. Every hospitalization that had an orthognathic surgery was selected. Patient and hospital level variables were examined. The odds of an orthognathic surgery procedure being performed in a teaching hospital over the study period was computed with the use of a multivariable logistic regression model. RESULTS: During the study period, a total of 108,264 hospitalizations underwent orthognathic surgeries in the United States. The average age ranged from 27 years during the years 2006-2008 to 28.2 years during the years 2000-2002. After adjusting for multiple patient and hospital level factors, the year of procedure was not a significant predictor of increasing odds of an orthognathic surgery being performed in a teaching hospital. CONCLUSIONS: There is no evidence of concentration of orthognathic surgical procedures in teaching hospitals.