Changes in facial width according to the ostectomy level of the proximal bone segment in intraoral vertical ramus osteotomy for mandibular prognathism.

BACKGROUND: This study aimed to investigate the changes in facial width according to the ostectomy level of the proximal segment after orthognathic surgery using intraoral vertical ramus osteotomy (IVRO) in patients with mandibular prognathism. METHODS: The participants included 32 individuals who were diagnosed with class III malocclusion prior to surgery. All participants underwent orthognathic surgery using either version of IVRO. The surgery patients were categorized into two groups depending on the type of proximal bone-segment ostectomy technique used: patients whose osteotomy height was at the level of the mandibular tooth occlusal surface (the mandibular tooth surface-level group) and patients whose osteotomy height was at the level of the mandibular inferior border (the mandibular inferior border-level group). The distances between the mandibular width and soft tissue width at the height of the sigmoid notch, mandibular foramen, and alveolar bone and at the anterior-posterior location of the mandibular condyle, mandibular foramen, and coronoid process were compared between the groups. All data were compared to identify differences between preoperative and postoperative measurements. RESULTS: The postoperative change in facial soft tissue width at the intersection of the coronal plane with the coronoid process and the horizontal plane at the height of the mandibular alveolar bone in the group with osteotomy at the level of the mandibular occlusal surface differed significantly from that in the group with osteotomy at the level of the mandibular inferior border, with respective increases (mean ± SD) of 1.3 ± 3.5% and 4.7 ± 5.6%, compared to preoperative measurements (p = 0.050). CONCLUSIONS: Proximal segment ostectomy at the level of the mandibular occlusal surface must be considered with regard to postoperative facial soft tissue width in vertical ramus osteotomy. Additionally, it is necessary to study the visual effect of the width of the mandible appearing small because of the posterior position of the mandible, even when the mandibular facial width is maintained.

Maxillary sinus haziness and facial swelling following suction drainage in the maxilla after orthognathic surgery.

BACKGROUND: We investigated the efficacy of a maxillary Jackson-Pratt (J-P) suction drain for preventing maxillary sinus hematoma and facial swelling after maxillary Le Fort I osteotomy (LF1). METHODS: We retrospectively evaluated 66 patients who underwent LF1 at a single institution. Of these, 41 had a J-P suction tube inserted in the mandible and maxilla (maxillary insertion), and 25 had a J-P drain inserted in the mandible only (no maxillary insertion). Facial CT was obtained before and 4 days after surgery. We compared mean midfacial swelling and maxillary sinus haziness by t test and examined correlations between bleeding amount and body mass index (BMI). RESULTS: For the maxillary-insertion group, the ratio of total maxillary sinus volume to haziness (57.5 ± 24.2%) was significantly lower than in the group without maxillary drain insertion (65.5% ± 20.3; P = .043). This latter group, however, did not have a significantly greater midfacial soft tissue volume (7575 mm3) than the maxillary-insertion group (7250 mm3; P = .728). BMI did not correlate significantly with bleeding amount or facial swelling. CONCLUSIONS: Suction drainage in the maxilla reduced maxillary sinus haziness after orthognathic surgery but did not significantly reduce midfacial swelling.

Effect of warfarin discontinuation on the incidence of postoperative bleeding in tooth extraction.

OBJECTIVES: The number of patients undergoing oral anticoagulant therapy for cardiovascular and cerebrovascular disease is increasing. However, the risk of bleeding after tooth extraction in patients receiving warfarin is unclear. Here, we assess the risk of bleeding after tooth extraction in patients on warfarin. MATERIALS AND METHODS: The study included 260 patients taking warfarin who underwent tooth extraction (694 teeth). The patients were divided into those whose teeth were extracted while they were taking warfarin, those who discontinued warfarin before extraction, and those who underwent extraction while receiving heparin bridging therapy. Bleeding complications in the two groups were compared. RESULTS: Of the 260 patients, 156 underwent extraction while taking warfarin, 70 stopped taking warfarin before extractions, and 34 received heparin bridging therapy and stopped taking either medication before extractions. Bleeding complications occurred in 9 patients (3.5%) and 9 tooth sites (1.3%). Among the 9 patients with bleeding complications, 6 underwent extraction while taking warfarin, 2 stopped warfarin before extraction, and 1 underwent extraction after receiving heparin bridging therapy. No significant difference was seen between patient groups regarding bleeding after extractions (P=0.917). CONCLUSION: Warfarin use does not increase the risk of post-extraction bleeding and can therefore be continued during tooth extraction.

The effect of bisphosphonate discontinuation on the incidence of postoperative medication-related osteonecrosis of the jaw after tooth extraction.

OBJECTIVES: The discontinuation of bisphosphonate (BP) treatment before tooth extraction may induce medication-related osteonecrosis of the jaw (MRONJ). Whether the long-term discontinuation of BP treatment before tooth extraction affects the risk of developing MRONJ after tooth extraction or whether extended drug holidays induce systemic side effects remains unclear. The present study assessed the incidence of MRONJ among patients who underwent tooth extraction and did not discontinue BP therapy prior to the procedure. MATERIALS AND METHODS: Patients were classified according to whether or not they discontinued BP therapy before tooth extraction. Differences in the incidence of MRONJ after tooth extraction were compared between the two groups using the chi-squared test. RESULTS: The BP-continuation (BPC) and BP-discontinuation (BPDC) groups included 179 and 286 patients, respectively. One patient in the BPC group and no patients in the BPDC group developed MRONJ (P=0.385). The patients in the BPDC group stopped receiving BP therapy at a mean of 39.0±35.5 months prior to tooth extraction. CONCLUSION: The possibility of pre-existing MRONJ in the extraction area must be considered during the extraction procedure. Routine discontinuation of BP medications for several months before the extraction procedure should be carefully considered, as evidence of its efficacy in reducing the development of post-extraction MRONJ is limited.

Antibiotic sensitivity and resistance of bacteria from odontogenic maxillofacial abscesses.

OBJECTIVES: This study investigated the types and antibiotic sensitivity of bacteria in odontogenic abscesses. MATERIALS AND METHODS: Pus specimens from 1,772 patients were collected from affected areas during incision and drainage, and bacterial cultures and antibiotic sensitivity tests were performed. The number of antibiotic-resistant bacteria was analyzed relative to the total number of bacteria that were tested for antibiotic susceptibility. RESULTS: Bacterial cultures from 1,772 patients showed a total of 2,489 bacterial species, 2,101 gram-positive and 388 gram-negative. For penicillin G susceptibility tests, 2 out of 31 Staphylococcus aureus strains tested showed sensitivity and 29 showed resistance. For ampicillin susceptibility tests, all 11 S. aureus strains tested showed resistance. In ampicillin susceptibility tests, 46 out of 50 Klebsiella pneumoniae subsp. pneumoniae strains tested showed resistance. CONCLUSION: When treating odontogenic maxillofacial abscesses, it is appropriate to use antibiotics other than penicillin G and ampicillin as the first-line treatment.

Surgical treatment of stage 2 medication-related osteonecrosis of the jaw compared to osteomyelitis.

OBJECTIVE: To compare the characteristics and outcomes of patients who underwent surgical treatment for stage 2 medication-related osteonecrosis of the jaw (MRONJ) versus osteomyelitis. METHODS: This retrospective study compared the following variables in 73 patients with stage 2 MRONJ versus 89 patients with osteomyelitis: impaired wound healing after surgery, sex, age, the presence of actinomycosis, location of the jaw lesion, and involvement of the inferior alveolar nerve (IAN). RESULTS: There were significant differences between the groups in age, sex, rates of impaired wound healing, actinomycosis, and the location (anterior/posterior) of the lesion. Impaired wound healing after surgical treatment in the stage 2 MRONJ group was associated with patient age. All patients with impaired wound healing after the initial surgery recovered fully after reoperation. CONCLUSIONS: These findings for surgical treatment of stage 2 MRONJ may help clinicians plan surgical treatment of MRONJ.

Accuracy of 3-Dimensional Virtual Surgical Simulation Combined With Digital Teeth Alignment: A Pilot Study.

PURPOSE: To evaluate the accuracy of virtual surgical simulation combined with digital teeth alignment and the applicability of this technique to the diagnosis and establishment of a 3-dimensional (3D) visualized treatment objective for orthognathic surgery by comparing virtual simulation images with actual post-treatment images. MATERIALS AND METHODS: This retrospective study included patients who underwent computed tomography (CT) before and after treatment. The 3D digital images were constructed from the initial CT images and dental cast scan data, and virtual surgical simulation combined with digital teeth alignment was performed. Accuracy of the virtual simulation was analyzed by comparing the distances of skeletal and dental landmarks in the horizontal, sagittal, and coronal reference planes with those on post-treatment images using the Wilcoxon signed rank test. Intraclass correlation coefficients were calculated to evaluate the degree of concordance between the 2 images. RESULTS: The study sample included 11 patients (mean age, 18.8 yr). Most landmarks had differences smaller than 2 mm in the 3 reference planes between virtual simulation and post-treatment images; these differences were not statistically significant (P > .05). Most skeletal landmarks, except the A point, B point, and gonion, showed normal to high concordance between the virtual simulation and post-treatment images in the 3 reference planes (P < .05); dental landmarks exhibited a broad range of concordance. CONCLUSION: The 3D virtual surgical simulation combined with digital teeth alignment using pretreatment CT images yielded results sufficiently accurate to be used for the diagnosis and establishment of visualized treatment objectives for orthognathic surgery.

Validation of a fibula graft cutting guide for mandibular reconstruction: experiment with rapid prototyping mandible model.

OBJECTIVE: We examined whether cutting a fibula graft with a surgical guide template, prepared with computer-aided design/computer-aided manufacturing (CAD/CAM), would improve the precision and accuracy of mandibular reconstruction. METHODS: Thirty mandibular rapid prototype (RP) models were allocated to experimental (N = 15) and control (N = 15) groups. Thirty identical fibular RP models were assigned randomly, 15 to each group. For reference, we prepared a reconstructed mandibular RP model with a three-dimensional printer, based on surgical simulation. In the experimental group, a stereolithography (STL) surgical guide template, based on simulation, was used for cutting the fibula graft. In the control group, the fibula graft was cut manually, with reference to the reconstructed RP mandible model. The mandibular reconstructions were compared to the surgical simulation, and errors were calculated for both the STL surgical guide and the manual methods. RESULTS: The average differences in three-dimensional, minimum distances between the reconstruction and simulation were 9.87 ± 6.32 mm (mean ± SD) for the STL surgical guide method and 14.76 ± 10.34 mm (mean ± SD) for the manual method. DISCUSSION: The STL surgical guide method incurred less error than the manual method in mandibular reconstruction. A fibula cutting guide improved the precision of reconstructing the mandible with a fibula graft.

Novel three-dimensional position analysis of the mandibular foramen in patients with skeletal class III mandibular prognathism.

PURPOSE: To analyze the relative position of the mandibular foramina (MnFs) in patients diagnosed with skeletal class III malocclusion. MATERIALS AND METHODS: Computed tomography (CT) images were collected from 85 patients. The vertical lengths of each anatomic point from the five horizontal planes passing through the MnF were measured at the coronoid process, sigmoid notch, condyle, and the gonion. The distance from the anterior ramus point to the posterior ramus point on the five horizontal planes was designated the anteroposterior horizontal distance of the ramus for each plane. The perpendicular distance from each anterior ramus point to each vertical plane through the MnF was designated the horizontal distance from the anterior ramus to the MnF. The horizontal and vertical positions were examined by regression analysis. RESULTS: Regression analysis showed the heights of the coronoid process, sigmoid notch, and condyle for the five horizontal planes were significantly related to the height of the MnF, with the highest significance associated with the MnF-mandibular plane (coefficients of determination (R(2)): 0.424, 0.597, and 0.604, respectively). The horizontal anteroposterior length of the ramus and the distance from the anterior ramus point to the MnF were significant by regression analysis. CONCLUSION: The relative position of the MnF was significantly related to the vertical heights of the sigmoid notch, coronoid process, and condyle as well as to the horizontal anteroposterior length of the ascending ramus. These findings should be clinically useful for patients with skeletal class III mandibular prognathism.

Single-tooth dento-osseous osteotomy with a computer-aided design/computer-aided manufacturing surgical guide.

This clinical note introduces a method to assist surgeons in performing single-tooth dento-osseous osteotomy. For use in this method, a surgical guide was manufactured using computer-aided design/computer-aided manufacturing technology and was based on preoperative surgical simulation data. This method was highly conducive to successful single-tooth dento-osseous segmental osteotomy.

The effect of orthognathic surgery on the lip lines while smiling in skeletal class III patients with facial asymmetry.

BACKGROUND: The aim of this study was to examine the relationship between improvements in lip asymmetry at rest and while smiling after orthognathic surgery in patients with skeletal class III malocclusion. METHODS: This study included 21 patients with skeletal class III malocclusion and facial asymmetry. We used preoperative and postoperative CT data and photographs to measure the vertical distance of the lips when smiling. The photographs were calibrated based on these distances and the CT image. We compared preoperative and postoperative results with the t test and correlations between measurements at rest and when smiling by regression analyses. RESULTS: There were significant correlations between the postoperative changes in canting of the mouth corners at rest, canting of the canines, canting of the first molars, the slope of the line connecting the canines, and the slope of the line connecting first molars. The magnitude of the postoperative lip line improvement while smiling was not significantly correlated with changes in the canting and slopes of the canines, molars, and lip lines at rest. CONCLUSIONS: It remains difficult to predict lip line changes while smiling compared with at rest after orthognathic surgery in patients with mandibular prognathism, accompanied by facial asymmetry.

Anterior tympanic plate fracture following extraction of the lower molar.

The present case report describes an external auditory canal injury following extraction of the lower molar. The external auditory canal was torn in the same fashion that occurs in an anterior tympanic plate fracture. This case demonstrates one of the rare complications associated with dental extractions.

Precision of fibula positioning guide in mandibular reconstruction with a fibula graft.

BACKGROUND: This study examined the usefulness of the fibula positioning guide for boosting the accuracy of mandible reconstructions. METHODS: Thirty mandibular rapid prototype (RP) models were allocated to experimental (N = 15) and control (N = 15) groups. For reference, we prepared a reconstructed mandibular RP model with a three-dimensional printer, based on surgical simulation. In the experimental group, a fibula positioning guide template and fibula cutting guide, based on simulation, were used to reconstruct the mandible with a fibula graft. In the control group, only the fibula cutting guide, with reference to the reconstructed RP mandible model, was used to reconstruct the mandible with a fibula graft. The two mandibular reconstructions were compared to the surgical simulation by registering images with the non-surgical right side of the mandible. On the reconstructed side, 3D measurements were compared between the surgical simulation and actual surgery, and the sum of differences was taken as the total error. RESULTS: The combined use of the fibula cutting and positioning guides produced a smaller total error (mean ± SD: 10.0 ± 7.9 mm) than the fibula cutting guide alone (12.8 ± 8.8 mm; p = 0.015). The greatest point error was the vertical error at the mesial point of the anterior fibula segment. The anteroposterior and lateral errors were not significantly different between groups. These results showed that these two methods were not significantly different, except in the total and vertical errors. CONCLUSIONS: Considering the CAD/CAM processes required for creating positioning devices, the benefit provided with a positioning guide justified its use over the fibula cutting guide alone.

Genioplasty using a simple CAD/CAM (computer-aided design and computer-aided manufacturing) surgical guide.

BACKGROUND: The present study introduces the design and fabrication of a simple surgical guide with which to perform genioplasty. METHODS: A three-dimensional reconstruction of the patient's cranio-maxilla region was built, with a dentofacial skeletal model, then derived from CT DICOM data. A surgical simulation was performed on the maxilla and mandible, using three-dimensional cephalometry. We then simulated a full genioplasty, in silico, using the three-dimensional (3D) model of the mandible, according to the final surgical treatment plan. The simulation allowed us to design a surgical guide for genioplasty, which was then computer-rendered and 3D-printed. The manufactured surgical device was ultimately used in an actual genioplasty to guide the osteotomy and to move the cut bone segment to the intended location. RESULTS: We successfully performed the osteotomy, as planned during a genioplasty, using the computer-aided design and computer-aided manufacturing (CAD/CAM) surgical guide that we initially designed and tested using simulated surgery. CONCLUSIONS: The surgical guide that we developed proved to be a simple and practical tool with which to assist the surgeon in accurately cutting and removing bone segments, during a genioplasty surgery, as preoperatively planned during 3D surgical simulations.

Precision of a CAD/CAM-engineered surgical template based on a facebow for orthognathic surgery: an experiment with a rapid prototyping maxillary model.

OBJECTIVE: We examined the precision of a computer-aided design/computer-aided manufacturing-engineered, manufactured, facebow-based surgical guide template (facebow wafer) by comparing it with a bite splint-type orthognathic computer-aided design/computer-aided manufacturing-engineered surgical guide template (bite wafer). STUDY DESIGN: We used 24 rapid prototyping (RP) models of the craniofacial skeleton with maxillary deformities. Twelve RP models each were used for the facebow wafer group and the bite wafer group (experimental group). Experimental maxillary orthognathic surgery was performed on the RP models of both groups. Errors were evaluated through comparisons with surgical simulations. We measured the minimum distances from 3 planes of reference to determine the vertical, lateral, and anteroposterior errors at specific measurement points. The measured errors were compared between experimental groups using a t test. RESULTS: There were significant intergroup differences in the lateral error when we compared the absolute values of the 3-D linear distance, as well as vertical, lateral, and anteroposterior errors between experimental groups. The bite wafer method exhibited little lateral error overall and little error in the anterior tooth region. The facebow wafer method exhibited very little vertical error in the posterior molar region. CONCLUSIONS: The clinical precision of the facebow wafer method did not significantly exceed that of the bite wafer method.

Modification of planned postoperative occlusion in orthognathic surgery, based on computer-aided design/computer-aided manufacturing-engineered preoperative surgical simulation.

In orthognathic surgery, it is important to have a planned postoperative occlusion. A 3-dimensional preoperative simulation, based on 3-dimensional optically scanned occlusion data, can predict how the planned postoperative occlusion will affect the maxilla-mandibular relationship that results from orthognathic surgery. In this study we modified the planned postoperative occlusion, based on computer-aided design/computer-aided manufacturing-engineered preoperative surgical simulations. This modification made it possible to resolve the facial asymmetry of the patient successfully with a simple bilateral intraoral vertical ramus osteotomy and no additional maxillary or mandibular surgery.

Surgery-first approach using a three-dimensional virtual setup and surgical simulation for skeletal Class III correction.

A 19-year-old woman presented to our dental clinic with anterior crossbite and mandibular prognathism. She had a concave profile, long face, and Angle Class III molar relationship. She showed disharmony in the crowding of the maxillomandibular dentition and midline deviation. The diagnosis and treatment plan were established by a three-dimensional (3D) virtual setup and 3D surgical simulation, and a surgical wafer was produced using the stereolithography technique. No presurgical orthodontic treatment was performed. Using the surgery-first approach, Le Fort I maxillary osteotomy and mandibular bilateral intraoral vertical ramus osteotomy setback were carried out. Treatment was completed with postorthodontic treatment. Thus, symmetrical and balanced facial soft tissue and facial form as well as stabilized and well-balanced occlusion were achieved.

Accuracy assessment of image-based surface meshing for volumetric computed tomography images in the craniofacial region.

BACKGROUND: Three-dimensional printing and computer-assisted surgery demand a high-precision three-dimensional mesh model created from computed tomography (CT) imaging data using an image-based meshing algorithm. We aimed to evaluate the three-dimensional geometric accuracy of surface meshes produced from CT images with commercially available software packages. METHODS: The CT images were acquired for 3 human dry skulls and 10 manufactured plastic skulls. Four commercially available software packages were used to produce the surface meshes in stereolithography (STL) file format. These CT-based STL surface meshes were registered and compared with three-dimensional optical-scanned reference mesh surface for evaluating the accuracy of the STL mesh produced with each software package. RESULTS: The surface geometries produced by the CT-image-based meshing process were all relatively accurate; differences from the three-dimensional optical-scanned data were in the voxel or subvoxel range. However, when comparisons with the three-dimensional optical-scanned surface data were performed in individual anatomic regions, we found significantly different accuracies of the CT-based STL surface meshes produced by the different software packages. CONCLUSIONS: We found that all 4 software packages showed reasonably good meshing accuracies for clinical use. However, the range of errors inherent in the CT-image-based meshing process demands that caution should be taken in selecting and manipulating the software to avoid potential errors in specific clinical applications.

Verification of the usability of a navigation method in dental implant surgery: in vitro comparison with the stereolithographic surgical guide template method.

OBJECTIVE: This study investigates the usefulness of a navigation method using a reference frame directly fixed to the mandible compared to the stereolithographic (STL) surgical guide template method in dental implant surgery. MATERIALS AND METHODS: Twenty rapid prototyping (RP) mandibular models were divided into two groups. Simulation surgery was performed using SimPlant software for both groups. The actual dental implants were placed in the RP models using a real-time navigation system or the surgical guide template, which was fabricated based on STL data by a 3-dimensional printer. Positional implantation errors were measured by comparing the simulation surgery implant positions to the actual postoperative implant positions. RESULTS: The vertical distance error of the top surface area in the first molar region was not significantly different between groups. Otherwise, the implantation method using real-time navigation showed greater errors except for the horizontal and vertical errors in the apical area of the canine region. CONCLUSION: The STL surgical guide template was associated with fewer errors than the real-time navigation method in dental implant surgery.