교정용 선재의 직경 증가를 위한 전기도금법과 무전해도금법의 비교연구

김재남,이기헌,황현식,성영은 전남대학교 치의학연구소 2002 구강과학 Vol.14 No.3

The purpose of this study was to evaluate electroless plating as a method to increase diameter of an orthodontic wire through comparison with eletroplating. After pretreatment for plating to the stainless steel orthodontic wire of 0.016 inch. the electoless plating was done under the condition of 90'c until the diameter of the wire was increased to 0.018 inch using Hessonic-Gr® which was sold by Shin-Pung metal. On the process of electroless plating the diameter of wire was measured every 5 minute to examine the increasing ratio of the wire's diameter per time unit. And to examine the uniformity, the diameter of each 3 points of the electroless-plated orthodontic wire was measured. An X-ray diffraction test was performed to analyze the nature of the plated metal and physical property test was made. Through the comparison with electroplating, following results were obtained. 1. In stiffness. yield strength, and ultimate strength of electroless plating wire group showed higher tendency than those of electroplated wire group, and in stiffness and ultimate strength there was statistically significant difference between two groups. 2. In the electroless plating wire group. the increasing ratio of the diameter was 0.O0461±0.00003 mm/5min (0.O0092 mm/min). In the electroplated wire group, that was 0.O0821±0.O0015 mm/min. 3. The results of uniformity test to measure the diameter of each 3 points showed a tendency of uniformity in all the two plating method. The results of this study suggest that the electroless plating wire is more close to the ready-made wire than electroplating wire in terams of the physical property. On the other hand. the length of plating time should be solved for the clinical application of electroless plating.

군집분석법에 의한 안면비대칭의 분류

윤일선,황현식,이기헌,성재현 전남대학교 치의학연구소 2001 구강과학 Vol.13 No.4

The purpose of this study was to classify the facial asymmetry by cluster analysis using the variables of the posteroanterior cephalogram, and to find out the characteristics of each group. The posteroanterior cephalogram and frontal facial photograph of one hundred orthodontic patients were used. Cluster analysis was executed using the measurements which indicated the degree of facial asymmetry. The resultant groups were compared each other according to the measurements to find out the characteristics of each group. Through the statistical analysis, following results were obtained. 1. Facial asymmetry was classified into five groups, A, B, C, D, and E, on the basis of menton deviation, apical base midline discrepancy and vertical difference of distance between right and left antegonions. 2. The degree of Menton deviation was severe in the group A, moderate in the group C and D, and mild in the group B and E. 3. Apical base midline discrepancy showed high value in the group A and C. 4. Antegonion was superiorly positioned on the same side of menton deviation in the group A and D, whereas it was superiorly positioned on the opposite side of menton deviation in the group B. 5. All measurements except the curvature of mandibular inferior border showed high value in the group A whereas very low in the group E. 6. While the characteristics of the group D were similar with those of the group A, the degree of difference was less in the group D. The group B showed unique characteristics as many measurements showed negative value. The above results suggest that facial asymmetry can be simply classified by cluster analysis on the basis of menton deviation, apical base midiine discrepancy and the vertical positional difference of antegonion between right and left sides.

수종의 역충전 재료의 치근단 밀폐력 비교

황윤찬,김선호,정선와,강인철,황인남,오원만 전남대학교 치의학연구소 2001 구강과학 Vol.13 No.4

방사선상 enhancement 정도에 따른 측모두부방사선규격사진 계측점 설정의 재현도

유황석,황현식,김왕식,김경근 전남대학교 치의학연구소 2001 구강과학 Vol.13 No.4

The purpose of this study was to evaluate the reproducibility of lateral cephalometric landmarks according to radiographic image enhancement, and to contribute to the identification of cephalometric landmarks. Lateral cephalograms of ten individuals were taken and stored into computer. The images were then enhanced up to four grades by Quick Ceph Image Pro^TM on condition that the gray-scale equalization number was 50 and the detail enhancement number was 50. After thirty two landmarks were identified on monitor images by five observers, the deviations from the mean, the distances estimated between identified points and the mean point of five identified points, were evaluated for each landmark at each enhancement grade. Through the statistical analysis, following results were obtained. 1. In case of unenhanced radiographic images, the inter-observer reproducibility of the landmarks showed a large variation. 2. The comparison of deviation from the mean according to the degree of radiographic image enhancement for each landmark showed that the inter-observer reproducibility was significantly different at 5 landmarks. 3. The landmark of pterygomaxillary fissure showed higher reproducibility at enhancement grade 1 and 2 images that at unenhanced images. So did the landmark of posterior nasal spine at enhancement grade 1 images, and the landmark of menton at enhancement grade 2, 3 and 4 images respectively. The above results suggest that the reproducibility of some landmarks can be increased by radiographic image enhancement during the identification of the lateral cephalometric landmarks on the monitor.

나사형 임플란트 고정체의 길이, 직경, 플랫폼 형태에 따른 임플란트와 주위조직의 응력분포

강지은,정현주,양홍서 전남대학교 치의학연구소 2002 구강과학 Vol.14 No.1

Seven finite element models were constructed in mandible having single screw-type implant fixture connected to the second premolar-shaped superstructure, in order to evaluate how the length, diameter and platform shape of a screw-type fixture influence the stress in the supporting tissue around fixtures. The superstructure were made using UCLA abutment, and connected to the fixture with abutment screw. Each finite element model was varied in terms of length, diameter, and platform shape of the fixture according to the commercial fixture(3i Implant Innovations Inc, Palm Beach Gardens, FL33410, USA) while the superstructure and the mandible with a single fixture placed in it shared no difference in terms of appearance. In each model, 250N of vertical load was placed on the central pit of an occlusal plane and 250N of oblique load placed on the buccal cusp. The stress distribution in the supporting tissue and the other components was analysed using 2-dimensional Finite element analysis and the maximum stress in each reference area was compared. 1. Under lateral loading, the stress was larger in the larger in the abutment/fixture interface, and in the crestal bone, compared to the stress pattern under vertical loading. 2. The amount of stress at the superstructure was similar regardless of the length, diameter and platform shape of a fixture. 3. Around the longer fixture, the stress was decreased at the bone crest and subjacent cancellous bone and increased in the cancellous bone area apical to the fixture. 4. Around the wider fixture, the stress was decreased at the abutment/fixture interface, and the bone crest and increased in the cancellous bone area apical to the fixture. 5. Around the fixture having wider platform, less stress was resulted at the abutnent/fixture interface and the upper part of the cortical bone, compared to the fixture having standard platform. In short, the stress distribution of the supporting tissue was affected by length, diameter, and platform shape of a fixture, and the fixture which was larger in diameter and length could reduce the stress in the supporting tissues at the bone-fixture interface and bone crest area.

백서에서 치아이동 후 보정기간 동안 교합이 치주조직 섬유의 재형성에 미치는 영향

정권희,이기헌,황현식,이석형 전남대학교 치의학연구소 2002 구강과학 Vol.14 No.2

The purpose of this study was to evaluate the effect of occlusion on the mechanical strength of periodontal fibers during retention periods after experimental tooth movement. In the Sprague-Dawley male rats weighing 200 g or more. The intraoral elastics was inserted into the interproximal space of upper the first and second molars. After 4th day of teeth movement, the left mandibular first, second, and third molars were extracted for differentiating the occlusal side from the non-occlusal side in the experimental groups. The intraoral elastics was removed and then light cured resin was placed in the interproximal space between the bilateral upper first and second molars following undercut was made for retention. From the day beginning retention, 7 rats were sacrified at 0, 4, 8, 12, 16, 20 days respectively. For evaluating of degree on the mechanical strength of periodontal tissue, maximal shear load of the bilateral upper first molars were measured by use of Instron Universal Testing Machine. The results of this study were obtained as follows: 1. In the occlusal side from no retention group to 4-day, 8-day, 12-day, 16-day, and retention 20-day group as time was going maximal shear load was increased and there was statistically difference from retention 12-day group(p<0.05). 2. In the non-occlusal side from no retention group to 4-day, 8-day, 12-day, 16-day, and retention 20-day group as time was going maximal shear load was increased slightly but there was no statistically difference(p>0.05). 3. The result compared with maximal shear load between occlusal and non-occlusal side showed no statistically difference until retention 8-daygroup(p>0.05), and showed statistically difference from retention 12-day to 20-day group(p<0.05). These results show that the occlusion had an effect on mechanical strength of the periodontal fibers during retention periods after experimental tooth movement; therefore, it is suggested that consideration of occlusion is required for the type and length of retention at the time of retention planning.

이하선 종양에 관한 임상적 연구

백승,오희균,박홍주,유선열,김원재 전남대학교 치의학연구소 2002 구강과학 Vol.14 No.3

This is a clinical study on 113 patients, who were treated for parotid tumors at Chonnam National University Hospital over a period of 5 years from January 1996 to December 2000. The results were as follow, 1. The mean ages were 42.6 years old (12~73 years) for benign parotid tumor patients and 43.9 years old (2~74 years) for malignant patients. 2. The ratio of male to female was 1:2 in malignant parotid tumors, but there was no difference in sex distribution of benign tumor. 3. There was no difference in mean mass size and duration of illness between benign and nalignant tumor patients. 4. The combined use of fine needle aspiration biopsy and computed tomograph was common as the diagnostic method of parotid tumor 5. The parotid tumors were commonly located in the superficial lobe(69%). 6. The ratio of benign and malignant tumors was 4:1. The most common benign tumor was pleomorphic adenoma (72% of benign tumor), followed by Warthin's tumor and monomorphic adenoma. The most common malignant tumor was rnucoeplderrnoid carcinoma(45% of malignant tumor). followed by adenoid cystic carnoma. carcinoma ex pleomorphic adenoma, and adenocarcinoma. 7. The most common operations were superficial parotidectomy (72%) for benign parotid tumor and total parotidectomy (45%) for malignant tumor 8. The most common postoperative complication was temporary facial nerve weakness (82%), followed by Frey's syndrome (14%) and permanent facial palsy (4%). 9. Postoperative radiation therapy was done in 12 patients and the mean radiation dose was 5550±620cGy. 10. Of 113 cases. tumor recurrence developed in 12 cases (10%). These results suggest that the successful management of parotid gland tumors needs adequate surgical treatment on the basis of knowledge of parotid gland anatomy and preoperative diagnosis.

하악골 후방 이동술 후 초기 교합안정과 회귀성향에 대한 변형된 상부자의 효과

류정호,김현진,김선헌,이은주 전남대학교 치의학연구소 2002 구강과학 Vol.14 No.2

Many surgeons have tried to reduce the skeletal relapse and temporomandibular discomfort resulted from inproper postoperative condyle position when has been known as a major complication of orthognathic surgery of mandibular prognathism, especially sagittal split ramus osteotomy. In the case of early anterior openbite, it has been known that postoperative condyle position is the most important factor concerned with relapse. Many studies to reduce these complications have been reported by reproducing the preoperative condylar position. Generally, if the condyle is fixed at the antero-inferior position, the early anterior openbite might be resulted from the lever action on the most posterior tooth by movement of condyle to physiologically stable position when the intermaxillary fixation is released. This study was carried out to elucidate whether the condyle could be positioned in the physiologically stable position by using the modified splint. Surgical wafer splint was manufactured in the condition that condyle of articulator was first moved anteriorly 1.73mm, inferiorly 1mm, and then occluded. The effects of the modified splint to early occusal stability and relapse was evaluated by physical examination and radiographic landmarks of cephalometrics. The results were as follows: 1. The usage of the modified splint helped the occlusal stability and reduced the rate of early anterior openbite. 2. It was acceptable for clinical application in aspects of temporomandibular discomfort. 3. Posterior openbite has rapidly compensated by the usage of the modified splint, and it was advantage to the prevention of early relapse. 4. The usage of the modified split resulted in the tendency of slightly anterior rotation of proximal segment, but it helped the repositioning of condyle into preoperative position. 5. It contributed to the occlusal stability by reducing anterior tooth movement, which was derived from compensational action of postoperative relapse. 6. The degree of inadvertent anteroposterior rotation of the proximal segment at surgery was correlated with the early skeletal relapse. These results suggest that the proximal segment fixation technique by using the modified splint have advantages to reduce the early skeletal relapse. This technique could be effectively used to the patients who had no facial asymmetry and do not need maxillary movement.

하악과두 골절에 대한 임상통계학적 연구

박충열,김병국 전남대학교 치의학연구소 2001 구강과학 Vol.13 No.3

The present study was aimed to aid the diagnosis and choose the approrpiate treatment method of the fracture. This is the retrospective clinicostatistical study about 87 patients who were treated about condylar fractures for recent 4 years from Apr. 1, 1996 to Apr. 30, 2000 in Chonnam National University Hospital and can be followed up reguarly. In the incidence of fractures, subjects in the twenties has highest incidence and male has 4.1 time higher prevalance than in female. The fracture was at the highest incidence in September. The most common cause of the fracture was traffic accident (40.2%), and in case of middle facial concomitant injuries, laceration was 45.1% and the fracture of symphysis was 57.1% in lower facial injuries. The most common site of the fracture was the condylar neck, followed by subcondye and condylar head in order. patients aged under 11 years were treated closed reduction which was 100% and for those aged over 19 years, open reduction (68%) was preferred. Most of them were fixed with metal miniplate in case of open reduction. The average period of fixation was 9.8 days, of which was 11.8 days for closed reduction and 8.5 days for open reduction. The average maximal mouth opening was lower in case of open reduction than in closed reduction in condylar head fracture. Closed reduction and direct fixation with Risdon showed better functional recovery than in SVRO cases. The complications like fibrous ankylosis and bone resorption of TMJ was happened in the case of open reduction with SVRO. These results suggest that the condylar fracture will be treated with closed reduction if patients are growing children and the fractured condyle was not displaced, otherwise the open reduction will be preferred. The closed reduction and the direct fixation with Risdon method showed better functional recovery than in SVRO method.

치은부에 이중인공진피(Terudermis^(�) 이식 후 조직학적 평가

김민정,정현주,류승희,박병주 전남대학교 치의학연구소 2003 구강과학 Vol.15 No.4

The autogenous free gingival graft is the most predictable procedure currently used to increase the width of the attached gingiva in periodontal therapy. But the major disadvantage of the procedure is to create the 2ndary multiple surgical wounds at both a donor site and a recipient site. The other problem is the limited amount of available graft material. Therefore, recent researches have been focused on the development of the biomaterial to substitute gingival tissue. The purpose of this study was to compare the histologic healing after grafting of bilayer artificial dermis and free gingival graft. Four non-smoking subjects (mean age, 32.5 years) in systemically healthy state and good oral hygiene were selected according to their particular needs for correction of mucogingival deformities as suggested by Nabers : 1) zones of minimal attached gingiva, 2) areas of thin gingiva, 3) areas of inadequate vestibular formation, and 4) frenum problems. The recipient sites were prepared through the conventional free gingival graft procedure and were grouped according to the graft materials : Experimental group-bilayer artificial dermis (Terudermis ; Terumo Co. Japan)(n=5) ; Control group-free gingival graft with autogenous palatal mucosa(n=6). Biopsies were harvested from 11 sites (containing adjacent attached gingiva and graft) at 1, 2, 3 and 6 weeks postsurgery to evaluate histologic healing. At the third week in the experimental group and at the second week of in the control group, the grafts has been stabilized on the recipient bed and the graft border has been blended into the surrounding tissue. In the experimental group, the epitheial migration from the adjacent tissue to graft was observed after 1 week of grafting and the distribution of the inflammatory cells were reduced, collagen layer of the artificial dermis was lost and the basement membrane was formed after 3 weeks of grafting. At 6 weeks of grafting, both groups demonstrated orthokeratinized epithelium and increased thickness of epithelial tissue, similar to the adjacent tissue and the rete peg formation. It was difficult to distinguish the graft from adjacent normal tissue. Histologic evaluation revealed a biologic acceptance and incorporation of the collagen layers of the graft tissue to the host tissue, without severe inflammatory response. In conclusion, a bilayer artificial dermis is essentially similar to autogeneous free gingival graft in the correction of mucogingival problems, and has the advantages of decreased patient morbidity(no donor site) and availability of abundant amounts of graft material when needed.