USE OF A COMPUTER NAVIGATION SYSTEM FOR OSTEOTOMIES IN THE ORTHOGNATHIC SURGERY: TECHNICAL NOTE

The Efficacy of Prophylactic Antibiotics for Mandibular Third Molar Extraction

This study analyzed the incidence of wound infection after the operation of mandibular third molar extraction in relation with antibiotic prophylaxis with the object of young and healthy patients. The study object was 1,177 mandibular third molars of 850 men of 20 to 25 years old without any specific systemic disease. Three methods of preventive antibiotic medication were selected according to the preventive antibiotic medication previously reported; three experimental groups were selected based on them, and the antibiotic used was amoxicillin((R)Kymoxin, Yuhanyanghaeng, Seoul). The group 1 includes the patients that took the antibiotic orally before the operation(one hour earlier, 500mg) and for three days after the operation(250mg per time, three times/day), the group 2 is the ones that took the same antibiotic orally only once about one hour before the operation(500mg), and the group 3 did not take any antibiotics before and after the operation. And to compare the difficulties and the degrees of extraction during operations which can be possibly related to the wound infection after the operations, the mandibular third molars' impacted depths and extraction methods were investigated as well. To check if the wound was infected, observations with an internal of one week were performed twice after the operation, and the meaningfulness of the infection incidence was verified through Chi-square test using SPSS program(SPSS Inc., IL, USA). There was no statistically significant difference between the antibiotic medication methods and the wound infection incidence after the operation among the experimental groups. As examining the relations between the mandibular third molar operation methods and the wound infection incidence after the operation, there existed a statistically meaningful difference in the infection incidence according to the operation methods(p=0.020). And there was no statistically significant difference in the wound infection incidence according to the impacted depth of the mandibular third molar. Therefore, it is thought that there exists little necessity of prophylatic antibiotics medication when extracting the mandibular third molar of young and healthy men without any systemic disease in general; however, in case when it is expected that the possibility of infection will be high or the wound on the tissue will be severe, it is sure that the prophylactic antibiotics medication will be necessary.

Image fusion accuracy for the integration of digital dental model and 3D CT images by the point-based surface best fit algorithm

PURPOSE: The goal of this study was to develop a technique for creating a computerized composite maxillofacial-dental model, based on point-based surface best fit algorithm and to test its accuracy. The computerized composite maxillofacial-dental model was made by the three dimensional combination of a 3-dimensional (3D) computed tomography (CT) bone model with digital dental model. MATERIALS AND METHODS: This integration procedure mainly consists of following steps : 1) a reconstruction of a virtual skull and digital dental model from CT and laser scanned dental model ; 2) an incorporation of dental model into virtual maxillofacial-dental model by point-based surface best fit algorithm; 3) an assessment of the accuracy of incorporation. To test this system, CTs and dental models from 3 volunteers with cranio-maxillofacial deformities were obtained. And the registration accuracy was determined by the root mean squared distance between the corresponding reference points in a set of 2 images. RESULTS AND CONCLUSIONS: Fusion error for the maxillofacial 3D CT model with the digital dental model ranged between 0.1 and 0.3 mm with mean of 0.2 mm. The range of errors were similar to those reported elsewhere with the fiducial markers. So this study confirmed the feasibility and accuracy of combining digital dental model and 3D CT maxillofacial model. And this technique seemed to be easier for us that its clinical applicability can good in the field of digital cranio-maxillofacial surgery.

Three dimensional linear measurement of proximal tibia in medial and lateral approach for bone harvesting

PURPOSE : The aim of this study was simply assessing linear measurements in the lateral and medial approach, respectively, for bone harvesting using anatomic and three-dimensional (3D) computed tomographic (CT) analyses on a dried cadaveric proximal tibia. In addition, the availability of the three-dimensional computed tomographic (3D-CT) analysis was also estimated. MATERIALS AND METHODS : Ten dried proximal tibia were obtained from five Korean cadavers. Four the reference points, the SM (superior-medial), IM (inferior-medial), SL (superior-lateral), and IL (inferior-lateral) were marked around the tibial tuberosity. The PM (posterior-medial) and PL (posterior-lateral) points were randomly marked at points farthest from the lateral and medial reference points, respectively, in the posterior border of the superior articular surface of both condyles. All measurements were obtained on the dried proximal tibia. After computed tomography had been performed, the three dimensional images were reconstructed using V works 4.0(TM) (Cybermed Inc., Seoul, Korea), and the length between the reference points were measured three dimensionally using the method described above. The error between the mean actual and mean 3D-CT measurements was calculated in order to determine the availability of the three dimensional computed tomographic analysis. RESULTS : The length between the reference points was greatest at the IL-PM, which averaged 65.39 mm+/-10.35. This was followed by the SL-PM with 63.24 mm+/-8.10, the IM-PL with 58.09 mm+/-10.02, and the SM-PL with 51.99 mm+/-9.06. The differences between the IL-PM and SM-PL were 13.4 mm. The mean values were 55.04 mm in the medial approach and 64.32 mm in the lateral approach, and the differences between medial and lateral were 9.28 mm. The error between the mean actual and mean 3D-CT measurements was 0.31% and the standard deviation was 0.28%. CONCLUSION : The anatomical and three dimensional computed tomographic analysis indicates that there was only a 9.28 mm linear difference between the lateral and medial approach. This is consistent with previous studies, which showed that there was little difference between the two approaches in terms of the bone volume. In addition, the error (0.31%) and the standard deviation (0.28%) were considered low, demonstrating high accuracy of 3D-CT. Therefore it can be used in preoperative treatment planning.

Accuracy of digital model surgery for orthognathic surgery: a preclinical evaluation

Intraosseous Nerve Sheath Tumors in the Jaws

Although the head and neck region is recognized as the most common location for peripheral nerve sheath tumors, central involvement, particularly in the jaw bones, is quite unusual. Neurofibroma is one of the most common nerve sheath tumors occurring in the soft tissue and generally appears in neurofibromatosis 1 (NF1 or von Recklinghausen's disease). Malignant peripheral nerve sheath tumors (MPNSTs) are uncommon sarcomas that almost always arise in the soft tissue. Here, we report four cases of intraosseous peripheral nerve sheath tumors occurring in the jaw bones and compare the clinical, radiologic, and pathologic findings in order to make a differential diagnosis.

Mandibulotomy, A Surgical approach for Oral cancer: Its Complications and contributing factors

We reviewed 56 patients who received mandibulotomy at Yonsei medical center between 1989 and 1999. We also analysed the complications associated with mandibulotomy and its contributing factors. The complications occur in 16 patients(28.6%) and are classified into two categories; intraoperative and postperative complications. Nonunion was observed in 5 patients and osteoradionecrosis in 5. The patients who received preoperative radiation therapy were more tend to develop nonunion and osteoradionecrosis. This study suggests the benefits of mandibulotomy as a surgical approach to oral cancer: 1. Paramedian osteotomy was recommended for preservation of neurovascular bundle and ease of surgical access. 2. By using thin saw blade, reapproximation was improved with minimal bone loss. 3. osteotomy on anterior mandible which lies outside the usual portals of radiation therapy decreases the incidence of osteoradionecrosis.