Luc Vrielinck

The significance of perineural spread in adenoid cystic carcinoma of the major and minor salivary glands.

Patient survival, local recurrence and distant metastasis were studied in relation to the pathological finding of perineural spread in 37 patients with adenoid cystic carcinoma of the major and minor salivary glands. All patients underwent a combined surgical and radiotherapeutical treatment. The overall incidence of perineural invasion in primary resection specimens was 52.6%. The 5-year actuarial survival rate for patients with perineural invasion was significantly lower (p less than 0.001) than for those without (36.9% versus 93.8%). In 26 patients with resection margins free of tumour, recurrences developed in 9/11 (81.8%) of the patients with perineural invasion as opposed to 4/15 (26.7%) of the patients without perineural invasion (p = 0.005). In the same group with resection margins free of tumour, distant metastasis developed after the primary treatment in 4/10 (40.0%) of the patients with perineural invasion, while none of the 14 patients without perineural invasion experienced distant metastasis (p less than 0.0002). The incidence of perineural invasion increased with a higher stage of the primary tumour.

Occurrence of bad splits during sagittal split osteotomy

OBJECTIVES The objectives of this study were to determine the incidence of bad splits in sagittal split osteotomies (SSOs), performed at the same hospital, and if the occurrence was reduced over time because of technical progress and/or surgical experience. Bad splits were defined as buccal or lingual plate fractures. STUDY DESIGN The files of all patients (n = 1008) who underwent bilateral or unilateral SSO between October 1989 and October 2009 were reviewed retrospectively. RESULTS A bad split occurred in 14 SSO sites (14 of 2005 sites). No bilateral bad splits occurred. There was no notable decrease of bad splits over the 20 years. All bad splits were resolved perioperatively by plate-osteosynthesis without the additional need of intermaxillary fixation. All patients with a bad split had a good and functional occlusion 6 months postoperatively. No infections occurred at the site of the bad splits. No bad splits occurred in patients younger than 20 years. No particular type of dental-facial deformity, or skeletal class according to the Angles classification could be correlated with cases of bad splits as a predisposing risk factor. CONCLUSION Even if precautions are taken, a bad split can occur during SSO of the mandible. This complication is manageable because of its low incidence (0.7 % of all SSOs) and uneventful healing. A significant decrease in incidence did not occur during the 20-year period, and neither technical progress nor the surgeons experience further reduced the incidence of bad splits.

Accuracy of upper jaw positioning with intermediate splint fabrication after virtual planning in bimaxillary orthognathic surgery.

Abstract The purpose of the study is to present and discuss a workflow regarding computer-assisted surgical planning for bimaxillary surgery and intermediate splint fabrication. This study describes a protocol starting from wax bite registration to fabrication of the necessary intermediate splint. The procedure is a proof of concept to replace not only the model surgery but also facebow registration and transfer from facebow to articulator. Three different modalities were utilized to obtain this goal: cone beam computed tomography (CBCT), optical dental scanning, and 3-dimensional printing. A universal registration block was designed to register the optical scan of the wax bite to the CBCT data set. Integration of the wax bite avoided problems related to artifacts caused by dental fillings in the occlusal plane of the CBCT scan. Fifteen patients underwent bimaxillary orthognathic surgery. The printed intermediate splint was used during the operation for each patient. A postoperative CBCT scan was taken and registered to the preoperative CBCT scan. The difference between the planned and the actual bony surgical movement at the edge of the upper central incisor was 0.50 ± 0.22 mm in sagittal, 0.57 ± 0.35 mm in vertical, and 0.38 ± 0.35 mm in horizontal direction (midlines). There was no significant difference between the planned and the actual surgical movement in 3 dimensions: sagittal (P = 0.10), vertical (P = 0.69), and horizontal (P = 0.83). In conclusion, under clinical circumstances, the accuracy of the designed intermediate splint satisfied the requirements for bimaxillary surgery.

Plate removal following orthognathic surgery

OBJECTIVES The objectives of this study were to analyze outcomes with miniplates in orthognathic surgery and define risk factors resulting in plate removal. STUDY DESIGN Clinical files of 570 orthognathic surgery patients operated between 2004 and 2009 were reviewed: 203 had a bimaxillary operation, 310 a lower jaw osteotomy, and 57 an upper jaw osteotomy. Age, sex, and jaw movement were analyzed. Reasons for hardware removal were recorded. RESULTS Hardware was removed in 157 patients (27.5%). Seventy-eight patients (13.7%) needed removal because of plate-related infection; 66 (11.6%) because of clinical irritation; 5 (0.9%) for dental implant placement; and 8 (1.4%) for other reasons. Average time between operation and removal was 9.9 months. More women (31.7%) than men (20.3%) had plates removed, but age was not a factor except with infection. CONCLUSIONS More than a quarter of patients developed complications from plates and screws, necessitating their removal, and infection occurred in 13.7%. Prompt removal constituted adequate management.

Validation of anatomical landmarks-based registration for image-guided surgery: An in-vitro study

INTRODUCTION Perioperative navigation is a recent addition to orthognathic surgery. This study aimed to evaluate the accuracy of anatomical landmarks-based registration. MATERIALS AND METHODS Eighty-five holes (1.2 mm diameter) were drilled in the surface of a plastic skull model, which was then scanned using a SkyView cone beam computed tomography scanner. DICOM files were imported into BrainLab ENT 3.0.0 to make a surgical plan. Six anatomical points were selected for registration: the infraorbital foramena, the anterior nasal spine, the crown tips of the upper canines, and the mesial contact point of the upper incisors. Each registration was performed five times by two separate observers (10 times total). RESULTS The mean target registration error (TRE) in the anterior maxillary/zygomatic region was 0.93 ± 0.31 mm (p < 0.001 compared with other anatomical regions). The only statistically significant inter-observer difference of mean TRE was at the zygomatic arch, but was not clinically relevant. CONCLUSION With six anatomical landmarks used, the mean TRE was clinically acceptable in the maxillary/zygomatic region. This registration technique may be used to access occlusal changes during bimaxillary surgery, but should be used with caution in other anatomical regions of the skull because of the large TRE observed.

Long-term success and survival rates of autogenously transplanted canines.

OBJECTIVES The objectives of this study were to determine the long-term survival and success rates of autotransplanted canines and to investigate the influence of various parameters on the long-term success rate. STUDY DESIGN Fifty-nine patients (73 transplanted canines) volunteered to participate in this study. The mean follow-up time was 11 years. Different parameters that could influence the outcome of transplantation were examined in the patient files. Each transplanted canine was clinically and radiologically evaluated. Logistic regression analyses were performed. RESULTS The survival rate was 75.3%, because 18 transplanted teeth were lost before examination. The success rate for all transplanted teeth was 57.5%, because 42 transplanted teeth were evaluated as clinically successful. The most significant parameter in determining the success rate of autotransplantation was age at transplantation (P = .0429). CONCLUSION Autotransplantation of impacted canines may have a successful outcome 11 years after transplantation. The success rate increases when performing the transplantation at a younger age.

CBCT-based predictability of attachment of the neurovascular bundle to the proximal segment of the mandible during sagittal split osteotomy

Injury to the inferior alveolar nerve (IAN) during surgery is an important complication of bilateral sagittal split osteotomy. With cone beam computed tomography, the course of the nerve and its relationship to the surrounding structures can be assessed in three dimensions. This study aims to determine whether tomography can predict attachment of the neurovascular bundle to the proximal segment of the mandible during sagittal split osteotomy (SSO). Bilateral linear measurements were taken on cross-sectional tomography images. During osteotomy, it was noted for each patient whether the neurovascular bundle was attached to the proximal segment during the split. If attached, a bone-cutting instrument or a blunt instrument was needed to free the nerve. The nerve was attached at more than one-third of operation sites (170 sites). Of these, over 65% of attached nerves (108 sites) required a bone-cutting intervention to free them from the mandible. After correcting for confounding factors, the linear distances from the buccal cortical margin of the IAN canal to the inner and outer buccal cortical margins of the mandible were important predictors of whether the IAN will be attached to the proximal segment of the mandible during SSO.

Risk factors for the development of lower border defects after bilateral sagittal split osteotomy

PURPOSE Defects at the lower border of the mandible may persist after bilateral sagittal split osteotomy (BSSO). The purpose of this study was to estimate the frequency of lower border defects after BSSO and to identify factors associated with the development of these defects. MATERIALS AND METHODS This retrospective study included patients who underwent BSSO at St Johns Hospital from January 2010 through December 2011. The predictor variables were length of advancement and inclusion of the full thickness of the lower border in the split. The outcome variable was the presence or absence of a lower border defect. Other variables were age and the side of the mouth. All analyses were performed using SAS 9.22. RESULTS The analysis included 400 operation sites in 200 patients (124 female, 76 male; median age, 24.5 yr; range, 14 to 57 yr). A defect at the mandibular border presented in more than one third of operation sites. Inclusion of the full thickness of the lower border in the split, length of advancement, side of the jaw, and age (P < .0001) were risk factors for a permanent defect at the lower border of the osteotomy gap after BSSO. CONCLUSIONS Inclusion of the full thickness of the lower mandibular border, the age of the patient, and the magnitude of advancement during BSSO are important predictors of whether a postoperative mandibular defect will remain after surgery. Surgeons should ensure that the lingual cortex of the lower border is not included in the split in large mandibular advancements.

Evaluation of 3 different registration techniques in image-guided bimaxillary surgery.

AbstractPerioperative navigation is an upcoming tool in orthognathic surgery. This study aimed to access the feasibility of the technique and to evaluate the success rate of 3 different registration methods—facial surface registration, anatomic landmark–based registration, and template-based registration. The BrainLab navigation system (BrainLab AG, Feldkirchen, Germany) was used as an additional precision tool for 85 patients who underwent bimaxillary orthognathic surgery from February 2010 to June 2012. Eighteen cases of facial surface–based registration, 63 cases of anatomic landmark–based registration, and 8 cases of template-based registration were analyzed. The overall success rate of facial surface–based registration was 39%, which was significant lower than template-based (100%, P = 0.013) and anatomic landmark–based registration (95%, P < 0.0001). In all cases with successful registration, the further procedure of surgical navigation was performed. The concept of navigation of the maxilla during bimaxillary orthognathic surgery has been proved to be feasible. The registration process is the critical point regarding success of intraoperative navigation. Anatomic landmark–based registration is a reliable technique for image-guided bimaxillary surgery. In contrast, facial surface–based registration is highly unreliable.

Obstructive airway compromise in the early postoperative period after orthognathic surgery

Abstract Between January 1, 1989 and April 30, 2012, approximately 2164 consecutive patients were treated with orthognathic surgery at the St. John’s Hospital, Genk, Belgium. They all underwent a mandibular, maxillary, or bimaxillary osteotomy, performed by one of the 3 resident maxillofacial surgeons at the St. John’s hospital in Genk. The purpose of the review was to investigate the incidence of major airway difficulties occurring postoperatively because of surgically related causes. It seemed that obstructive airway compromise was the only reason for urgent intervention to protect or to restore the airway. In total, 3 urgent unanticipated life-saving reintubations were attempted. One was successful, and the other was changed into an urgent tracheostomy. No deaths occurred in this patient series after orthognathic surgery. Osseous genioplasties, as stand-alone surgery or in combination with other simultaneous orthognathic procedures, do care the risk for a life-threatening respiratory distress because of a hematoma of the floor of the mouth, when performed with an oscillating saw or a surgical drill. If so, this probably will happen within the first 4 postoperative hours according to the experience in our series. This risk can be avoided by using a piezosurgical unit to perform the osseous genioplasty.