A Study Of Von-Mises Yield Strength After Mandibular Sagittal Split Ramus Osteotomy

For the study of its stability when the screw has been fixed after sagittal split ramus osteotomy(SSRO) of the mandible, the methods of screw arrangement are classified into two types, triangular and straight. The angles of screws to the bone surface are classified as perpendicular arrangements, the 60degrees anterioinferior screw, known as triangular, and the most posterior screw, called straight arrangement, thus there are four types. The finite element method model has been made by using a three dimensional calculator and a supercomputer. The load directions are to the anterior teeth, premolar region, and molar region, and the bite force is 1 Kgf to each region. The distribution of stress, the von-Mises yield strength, and safety of margin refer to the total sum of transformed energy have been studied by comparison with each other. The following conclusion has been researched : 1. When shear stress is compared, in the triangular arrangement in the form of "giyeok", the anterosuperior screw is seen at contributing to the support of the bone fragment. In the straight arrangement, substantial stress is seen to be concentrated on the most posterior angled screw. 2. When the von-Mises yield strength is compared, it seemed that the stress concentration on the angled anteroinferior screw is higher, it shows a higher possibility of fracture than any other screw. In the straight arrangement, stress appeared to be concentrated on the most posteriorly angled screw. 3. When the safety margins of the transfomed energy are compared, the energy conduction is much greater in the case of the angled screw than in the case of the perpendicular screw. The triangular arrangement in the form of "giyeok" shows a superior clinical sign to that of the straight arrangement. Judging from the above results, when the screw fixation is made after SSRO in practical clinical cases, two screws should be inserted in the superior border of mandibular ramus and a third screw of mandibular inferior border should be inserted in the form of triangular. All screws on the bony surface should be placed perpendicularly-90 degrees angles apparently best promote bony support and stability.

Treatment Outcome Of Mandibular Condylar Fracture With Arthrocentesis And Lavage

In the treatment of mandibular condylar fractures, arthrocentesis, lavage and selective intermaxillary fixation were performed after closed reduction. In this lavage group, the physiotherapy performed for 3-6 months after injury. in control group, continuous intermaxillary fixation was done for 1-3 weeks, and physiotherapy followed in the same method of the lavage group. In the comparative study of the both groups, the following results are shown. 1. Compared to control group, the lavage group had a slightly superior result at range of motion, joint pain and occlusal deviation, from I day after arthrocentesis to 6 months after injury. 2. The significant differences between both groups were seen at range of motion and joint pain in 1 month after injury. 3. At 6 months after injury, the differences between both groups were not significant at range of motion, joint pain and occlusal deviation. From this study, in the mandibular condylar fracture, the arthrosentesis, lavage and selective intermaxillary fixation after closed reduction can improve symptoms such as joint pain and occlusal deviation, also increase range of motion. in this therapeutic way, intracapsular hemarthrosis which can cause TMJ ankylosis or dysfunction can be removed effectively. in addition, patient's discomfort such as swallowing disturbance, speech disturbance and emotional stress can be reduced signuficantly.

Clinical Applications Of Collagen Membrane Terudermis On Mucosal Defects

Clinical cases of true tmj ankylosis using various operative methods

A CLINICAL AND STATISTICAL STUDY OF CONDYLAR FRACTURE OF MANDIBLE

This is a retrospective study on condylar fracture of mandible. The stucy based on a series of 112 patients who had treated for the fractures of mandibular condyle on Kyunghee Dental Hospital from January, 1989 to August 1997. We studied the age and sex distributions, causes of fractures, location of fractures and so on. The results as follow : 1. The ratio of male : female was 4:1, and the highest frequency of condylar fractures was registered among patients aged to 21 to 30 years. 2. The most common cause of condylar fractures was fall-down(47.7%), followed in incidence by direct-blow(27.9%) and traffic accidents(20.7%). 3. Subcondylar fracture had highest incidence(50%), and followed by condyle head(27.4%) and condylar neck(22.6%). 4. 9.7% of condylar fractures had occurred bilaterally and in cases of bilateral condylar fractures, condylar head fractures(58.33%) was hightest incidence. 5. Mandibular symphysis was most commonly involved in condylar fracture(63.4%), and 27.7% of condylar fractures had not any other mandibular fractures.

THE EFFECT OF ERBIUM: YAG LASER OSTEOTOMY ON BONE HEALING

Presently, Erbium:YAG laser, which is known as laser for osteotomy, is considered to have good resection effects and to bring about minimum thermal damage. Since studies on this has never been done within the country and left as a field still unexplored, I expect to use this study as experimental data on future use of laser on hard tissue. In this report, both surgical bur(diameter 0.5mm carbide roun bur) and Erbium:YAG laser(100mJ/pulse, 10pulse/sec) was used each on the femur of white mouse and after the same amount of osteotomy, the effect of bone healing on the light microscope was observed and comparative study was made histology. The results are as follows : 1. In the first group (1st day, 3rd day), the osteotomic bone portion of the experimental group was irregular with bone resorption and showed more blood cell infiltration, compared with the control group. 2. At 1 week, bone matrix and immature bone was formed in the peripheral and center of the resection area in the control group. But inthe experimental group, more bone formation was initiated in the peripheral than in the center and showed more infiltration of blood cells and inflammatory cells. 3. At 2 week, bone matrix became mature to have similar density with compact bone and showed new formed vessels in the control group. But in the experimental group, bone formation with decreased density was initiated and new formed vessels together with mature bones was observed. 4. At 3 week, mature bone with equal density and regular trabecular pattern was observed in the control group. But in the experimental group, the continuity between the new bone and old bone was rather loose with decreased maturity, but on the other hand, had even bone formation pattern. 5. At 4 week, both the control and experimental group showed perfect bone healing features. From the results above, I can observe that in osteotomy with Erbium:YAG laser bone healing is rather delayed in each step but if, effective percentage of resection could obtained it would be valuable to substitute mechnical bur or saw and bring about much progress and development in the area of oral and maxillofacial surgery. For this, more studies on bone resection and biomechanical strength of bone tissue after bone healing should be done on various animals.

MALIGNANT FIBROUS HISTIOCYTOMA OF THE MAXILLA : REPORT OF TWO CASES

The clinical effects of Nd: YAG laser application after extraction

Nd:YAG laser is well absorbed to water, melanin, hemoglobin and thus, Nd:YAG laser may be used for bleeding control and extraction site sterilization where is easily contaminated by saliva and blood. Additionaly, Nd:YAG laser have analgesic effect by elevation of pain threshold. On the basis of Nd:YAG laser effects, we applied the Nd:YAG laser on extraction socket of 50 patients who visited to our department for lower third molar extraction and evaluated the effects of Nd:YAG laser on the bleeding control, pain relief, swelling reduction after tooth extraction. For the objective assesment on Nd:YAG laser effects, we made up the other 50 patients(control group) who were treated by conventional extraction method and compare the subjective and objective symptoms(pain relief, swelling and oozing time) between each group. The results were as follows: 1. The Nd:YAG laser was effective to relief of postextraction pain and most effective to 2 hours after extraction when local anesthesia disappears. 2. The Nd:YAG laser application was non-effective to reducing the facial swelling after extraction. 3. The Nd:YAG was effective to decrease the oozing time after extraction and the average time was 4 hours.

Clinical study on the fasical space infections of oral & maxillofacial region for recent 5 years

Maxillofacial infection often place the oral and maxillofacial surgeon in situations where timely decisions have to be made. These decisions can be lifesaving. Odontogenic infection are frequently encountered in the practice of oral and maxillofacial surgery. These infections often repond to surgical and antimicrobial management. Otheriwise odontogenic infections have the potential to spread via the fasical spaces in the head and neck region. They can compromise vital structures in this region or involve distant structures. The classic signs of maxillofacial infections include pain, swelling, fever, dysphagia, and dehydration. The goals of management should be to correct these conditions. We have undertaken clinical studies on infections in the oral and maxillofacial regions (facial space) by analyzing hospitalized patients in the Dept. of Oral and Maxillofacial Surgery, Kyung Hee University Hospital past 5 years from 1991. To 1995. And bacterial cultures and antibiotics sensitivity test were performed and the comparative analysis of the antibiotics was done. The results were as follows: 1. The most frequent cause of oral and maxillofacial infection was odontogenic 68% and in 23% patients with signs and symptom aggrevated after teeth extraction. 2. The most common fascial spaces involved was buccal space 36.1%, followed by submandibular space 12.3% and 3 cases were Ludwig's angina. 3. Antibiotics were administrated in all cases and surgical incision and drainage was performed in 88.6%. 4. The most causative organisms isolated from the pus cultures were streptococci group 51.1%.

A case report of ameloblastic fibro-odontioma of the mandible

This is a case report and review of literature of a rare mixed odontogenic tumor, ameloblastic fibro-odontoma in the posterior area of the mandible. The ameloblastic fibro-odontoma which was developed by hyperplasia of dental epithelium and mesenchymal tissue. This tumor was classified from ameloblastic odontoma by Hooker, in 1967. At first and characterized by mixed appearance of odontoma and ameloblastic fibro-odontoma, But, on the point of pathologic feature, there are many controversial opinions among scholars up to the present. The patients of this case report was refereed to our department via the pedodontic department for the treatment of hard mass on the premolar area of the left mandible. And then, on the clinical and radiographic examination at first visit, we had tentative diagnosis that the lesion was benign mixed odontogenic tumor of defined mass margin that was amelblastic fibro-odontoma. The tumor mass was removed by surgical enucleation and curettage and extracted left mandibular second premolar which was impacted on the lesion. And the removed tumor mass was confirmed to ameloblastic fibro-odontoma on the post-operative biopsy. The patients has well done follow-up check postoperatively and shown no sign of recurrence up to the present.