• The Journal of Korean Academy of Prosthodontics
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• v.36 no.1
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• pp.1-17
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• 1998

두개의 임플랜트로 지지되는 overdenture를 이용한 하악무치악환자의 치료법은 경제적이면서, 실용적인 치료로 인정을 받고 있다. 하지만 해부학적인 조건으로 임플랜트를 설측 혹은 후방에 식립해야 되는 경우에는 일반적인 bar설계는 bar가 구강저 상방을 지나게 되어 혀운동, 발음, 위생관리 등에 많은 문제점을 부여한다. 이에 대한 해결방법으로 전방부 치조제 상에 보철물의 회전을 허용하는 angular bar를 설계할 수 있다. 하지만 이 설계는 임플랜트에 불리한 moment를 유발한다. 그럼에도 불구하고 뛰어난 유지력과 지지능력, 경제적인 면 때문에 angular bar는 임상에서 많이 사용되고 있다. 이에 본 연구는 angular bar의 전방 cantilever양을 달리하여 임플랜트 및 주변조직에 미치는 영향을 삼차원 유한요소분석법을 통해서 알아보고자 하였다. 이공사이의 하악골을 단순화시킨 준하악골모형에 직경 3.75mm인 브로네마르크 임플랜트 2개를 길이가 13,15mm인 경우로 설정하여 제 1소구치 부위에 식립하였다. 두 임플랜트를 연결하는 bar는 전방부 cantilever양을 0-5mm, 1mm씩 하여 6가지 경우를 가정하고 제작하였다. 각각 bar 중앙부에 수직압 (90도) 35N, 경사압(120도) 70N, 수평압(0도) 10N을 가하였으며 이때 나타나는 응력 분산형태와 임플랜트의 골유착에 불리하게 작용하는 최대주응력(인장력)과 변위량을 살펴보았다. 연구결과 다음과 같은 결론을 얻었다. 1. Cantilever양이 증가할수록 주변피질골과 임플랜트로 응력이 집중되었으며 상부 보철물의 변위량도 커졌다. 2. Cantilever양에 대한 수평압의 영향은 크지 않았으며 임플랜트 길이가 긴 것이 변위량과 응력이 작았다. 3. 경사압에 대한 응력의 변화는 cantilever양의 증가에 따라 급격히 증가하는 양상을 띠었으며 임플랜트길이가 응력 및 변위의 양에 미치는 영향은 없었다. 4. 수직압에 대한 응력의 변화는 초기에는 완만한 증가를 보이다가 일정 시점 지난 후에는 증가율이 커지는 경향을 띠었다. 증가현상이 두드러지기 전에는 길이의 증가가 응력의 분산효과는 가져왔으나 이후에는 길이의 응력분산 효과는 없었다. 5. 응력분포양상은 cantilever양이 증가할수록 골조직을 통한 분산정도는 작아지고 특정부위의 피질골과 임플랜트, 상부보철물에 집중되는 경향을 보였다. 6. 임플랜트와 주변 골조직으로의 응력분산능력이 예후를 좌우한다는 점에서 angular bar는 적합치 못하며 부득이한 경우는 임플랜트 길이를 길게 하고 최대한 3mm이내로 cantilever양을 제한하는 것이 추천된다.

• Journal of Periodontal and Implant Science
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• v.33 no.4
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• pp.563-571
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• 2003

One of the central components of periodontal therapy is the improvement of esthetics. The presence and appearance of interdental papillae plays an important role of periodontal esthetics. The aim of the present study was to investigate how immediate provisional restoration preserve the shape of interdental papilla around the extraction socket and the width of bucco-lingual of gingiva. Another aim was to investigate the change in the interdental papilla and the amount of vertical bone fill of a extraction socket in relation to the interdental alveolar bone levels adjacent the alveolar socket. A total of 19 patients (11 male, 8 female, mean age of 50.57${\pm}$8.16), who visited the Department of Periodontology, Pusan National University and had more than one anterior tooth scheduled to be extracted due to an advanced periodontal disease were included in the present study. After initial periodontal therapy, the extracted teeth were reshaped of the root and placed into the socket followed by splinting with adjacent teeth with self-curing resin. The width of hucco-lingual of gingiva and interdental papilla height were measured at baseline, 1, 3, 6, 9 and 12 month and the periapical radiographic examination were taken at baseline, 6 and 12month following the extraction. The amount of vertical bone fill in the extraction socket were calculated. At 12 months following the extraction, the changes in mesial and distal interdental papilla and the width of bucco-lingual showed -1.06${\pm}$0.48mm, -0.844${\pm}$0.50mm, -1.50${\pm}$0.96m, relatively. The positional change in the interproximal papillae was significantly associated with the interdental bone level adjacent to the extraction socket(p=0.028). The higher the interproximal bone level adjacent the extraction socket, the greater the amount of bone fill in the extraction socket(p<0.001). In conclusion, it was thought that immediate provisional restoration could minimize the loss of the width of bucco-lingual and interproximal papillae around the extraction socket. In addition, the higher the interproximal bone level adjacent the extraction socket, the greater the amount of bone fill and the smaller the reduction of papillary height around the extraction socket.

• Journal of Periodontal and Implant Science
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• v.26 no.4
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• pp.933-948
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• 1996

The purpose of this study was to examine the anatomic structures of the mandible-inferior alveolar canal, mental foramen, mental canal-with panoramic radiography and conventional tomography and to compare both radiographic techniques in conjunction with endosseous implants. In this study 14 adult dentulous mandibles -27 cases of right and left side of mandibles- were examined and the results were as follows. 1. The distance between superior border of the inferior alveolar canal and the alveolar ridge crest showed a decreasing tendency from the mental foramen to 4cm posterior to the mental foramen. 2. The mean diameter of the inferior alveolar canal was $4.11{\pm}0.50mm$ with panoramic radiography and $3.29{\pm}0.59mm$ with conventional tomography. 3. The inferior border of the inferior alveolar canal and inferior border of the mandible was closest at 2cm posterior to the mental foramen but it was not statistically significant. the mean distance was $1l.64{\pm}2.95mm$ in panoramic radiography and $1l.68{\pm} 2.91mm$ in conventional tomography. 4. The inferior alveolar canal located lingually in bucco-lingual direction 16%(mental foramen), 54%(lcm posterior to the mental foramen), 68%(2cm posterior to the mental foramen), 50%(3cm posterior to mental foramen), 55%(4cm posterior to the mental foramen). 5. Mean length of the anterior loop of the mental canal was 2.73mm, and the loop below 2mm was 35% and 15% of mental canal was invisible in panoramic radiography. 6. The minimum interforaminal distance was 56.7mm, the maximum distance was 73.2mm and the mean distance was 66.42mm in panoramic radiography. 7. The mean distance between midpoint of the mental canal and alveolar ridge crest was 16.24mm and the mean buccolingual angulation of the mental canal was $52.98^{\circ}$ in conventional tomography. 8. In comparison of panoramic radiography and conventional tomography, inferior alveolar canal is better visualized with conventional tomography than panoramic radiography from the mental foramen to the 2cm posterior to the mental foramen, while visiblity of conventional tomography prominently decreased in 4cm posterior to the mental foramen and alveolar ridge crest is better visualized with panoramic radiography than conventional radiography at the mental foramen and at 4cm posterior to the mental foramen. In radiologic examination of anatomic structures of the mandible for endosseous implants, panoramic radiography and conventional tomography can be effectively used when it is used to overcome the anatomic limitations.

• Journal of Periodontal and Implant Science
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• v.27 no.2
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• pp.317-328
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• 1997

Since laser therapy has been applied to dentistry, many dental practitioners are very interested in laser therapy on various intraoral soft tissue lesions including gingival hyperplasia and aphthous ulcer. The purpose of the present study was to determine the therapeutic effect and the harmful effect of a pulsed-Nd:YAG laser irradiation on human gingival tissue. In twenty periodontal patients with gingival enlargement, the facial gingival surface of maxillary anterior teeth was randomly irradiated at various power of 1.0W(100mJ, 10Hz), 3.0W(100mJ, 30Hz) and 6.0W(l50mJ, 40Hz) for 60 seconds by contact delivery of a pulsed-Nd:YAG laser(EN.EL.EN060, Italy). Immediately after laser irradiation, the gingival tissues were surgically excised and prepared in size of 1mm3. Subsequently the specimens were processed for prefixation and postfixation, embedded with epon mixture, sectioned in $1{\mu}$ thickness, stained with uranyl acetate and lead citrate, and observed under transmission electron microscope(JEM 100 CXII). Following findings were observed; l. In the gingival specimens irradiated with l.OW power, widening of intercelluar space and minute vesicle formation along the widened intercellular space were noted at the epithelial cells adjacent to irradiated area. 2. In the gingival specimens irradiated with 3.0W power, the disruption of cellular membrane, aggregation of cytoplasm, and loss of intercellular space were observed at the epithelial cells adjacent to irradiated area. 3. In the gingival specimens irradiated with 6.0W power, the disruption of nuclear and cellular membrane was observed at the epithelial cells adjacent to irradiated area. The ultrastructural findings of this study suggest that surgical application of a pulsed-Nd:YAG laser on human gingival tissue may lead somewhat delayed wound healing due to damage of epithelial cells adjacent to irradiated area.

• Journal of Periodontal and Implant Science
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• v.27 no.2
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• pp.363-377
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• 1997

The main goal of periodontal therapy is the regeneration of periodontal tissue which has been lost due to destructive periodontal diseases. Although conventional forms of periodontal therapy show sound clinical results, the healing results in long junctional epithelium. There have been numerous materials and surgical techniques developed for new attachment and bone regeneration. Bone grafts can be catagorized into: autografts, allografts, xenografts and bone substitutes. Synthetic bone substitute materials include hydroxyapatite, tricalcium phosphate, calcium carbonate, and Plaster of Paris. Calcium sulfate has found its use in dental practice for the last 30 years. Recent animal studies suggest that periodontal regeneration in 3 wall intrabony defect may be enhanced by the presence of calcium sulfate. And it is well known that 2 wall & 1 wall defect have less osteogenic potential, So we need to study the effect of calcium sulfate in 1 wall intrabony defect in dogs. The present study evaluates the effects of calcium sulfate on the epithelial migration, alveolar bone regeneration and cementum formation in intrabony defects of dogs. Four millimeter-deep one-wall intrabony defects were surgically created in the mesial aspect of anterior teeth and mesial & distal aspects of premolars. The test group received calcium sulfate grafts with a flap procedure. The control underwent flap procedure only. Histologic analysis following 8 weeks of healing revealed the following results: 1. The lengths of junctional epithelium were: 2.52mm in the control, and 1.89mm in the test group. There was no statistical significance between the two groups. 2. Alveolar bone formation were: 0.61mm in the control, and 1.88mm in the test group. There was a statistically significant difference between the two groups (p<0.05). 3. Cementum formations were: l.lmm in the control, and 2.46mm in the test group. There was a statistically significant difference between the two groups (p<0.05). 4. The length of CT adhesion were: O.97mm in the control, and 0.17mm in the test group. There was no statistically significant differences between the two groups These results suggest that the use of calcium sulfate in intrabony defects has little effect on junctional epithelium migration, but has significant effects on new bone and new cementum formations.

• Journal of Periodontal and Implant Science
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• v.46 no.6
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• pp.372-381
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• 2016

Purpose: The aim of this study was to determine the relationship between buccal bone thickness and gingival thickness by means of a noninvasive and relatively accurate digital registration method. Methods: In 20 periodontally healthy subjects, cone-beam computed tomographic images and intraoral scanned files were obtained. Measurements of buccal bone thickness and gingival thickness at the central incisors, lateral incisors, and canines were performed at points 0-5 mm from the alveolar crest on the superimposed images. The Friedman test was used to compare buccal bone and gingival thickness for each depth between the 3 tooth types. Spearman's correlation coefficient was calculated to assess the correlation between buccal bone thickness and gingival thickness. Results: Of the central incisors, 77% of all sites had a buccal thickness of 0.5-1.0 mm, and 23% had a thickness of 1.0-1.5 mm. Of the lateral incisors, 71% of sites demonstrated a buccal bone thickness <1.0 mm, as did 63% of the canine sites. For gingival thickness, the proportion of sites <1.0 mm was 88%, 82%, and 91% for the central incisors, lateral incisors, and canines, respectively. Significant differences were observed in gingival thickness at the alveolar crest level (G0) between the central incisors and canines (P=0.032) and between the central incisors and lateral incisors (P=0.013). At 1 mm inferior to the alveolar crest, a difference was found between the central incisors and canines (P=0.025). The lateral incisors and canines showed a significant difference for buccal bone thickness 5 mm under the alveolar crest (P=0.025). Conclusions: The gingiva and buccal bone of the anterior maxillary teeth were found to be relatively thin (<1 mm) overall. A tendency was found for gingival thickness to increase and bone thickness to decrease toward the root apex. Differences were found between teeth at some positions, although the correlation between buccal bone thickness and soft tissue thickness was generally not significant.

• Journal of Periodontal and Implant Science
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• v.27 no.4
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• pp.819-828
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• 1997

The purpose of this study was to evaluate the abrasion-resistance of root surface after NaF iontophoresis, Nd:YAG laser irradiation and combined treatment 50 anterior teeth with flat interproximal root surface that had been extracted due to periodontal destruction were selected. All teeth were treated by the same procedure as conventional periodontal root treatment, such as scaling and root planing, root conditioning with tetracycline HCI(lOOmg/ml, 5min). The pre-treatment weight of each tooth was measured by a dial scale(SHIMADEU Co, LIBROR EB-220HU, capacity 220.000 g, Japan). All teeth were divided into 5 groups as follows: Nd:YAG laser irradiation(group 1, 1 W, 100 mJ, 10Hz, fiberoptic-root surface distance=5mm, $10\;sec.{\times}6times$, EL.EN.EN060, Italy): NaF iontophoresis(group 2, $150{\mu}A$, 4 min}: Nd:YAG laser irradiation following NaF iontophoresis(group 3): NaF iontophoresis following Nd:YAG laser irradiation(group 4): No treatment(control group). Electric toothbrushing (Oral-B, Brown Co, Germany) was conducted during 1 hour($lO\;min.{\times}6\;times$). Subsequently post-treatment weight was remeasured by the same method as pre-treatment weight measurement. The difference of abrasion rate among all groups was statistically analyzed by ANOVA(SAS program). Following results were obtained: 1. The abrasion rate was significantly lower in Nd:YAG laser irradiation group than NaF iontophoresis group(p < 0.001). 2. The abrasion rate was significantly lower in combined groups of Nd:YAG laser irradiation and NaF iontophoresis than either Nd:YAG laser irradiation group or NaF iontophoresis group(p < 0.001). 3. There was no significant difference in abrasion rate according to application order in the combined groups(p > 0.05). 4. The abrasion rate was significantly lower in all experimental groups than control group(p < 0.001). The results suggest that combined treatment of Nd:YAG laser irradiation and NaF iontophoresis on exposed root surface after periodontal therapy can enhance the abrasion-resistance of root surface and may inhibit the root caries development.

• Journal of Chest Surgery
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• v.22 no.2
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• pp.220-224
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• 1989

In candidates for aortic valve replacement [AVR]it is our primary intention to implant the largest possible vale prosthesis of at least 23 mm in diameter in patients with severe valvular aortic stenosis. However, in many patients there is an additional subvalvular asymmetric septal hypertrophy which in some cases may cause an postextrasystolic increase of the LV-aortic gradient. Another component of the aortic stenosis syndrome is a narrow valvular ring, or a combination of both. After complete removal of the diseased valve and decalcification the narrow aortic ring [< 23 mm] can be widened firstly by transaortic subvalvular septal myectomy- [TSM] thus unfolding the left ventricular outflow tract[LVOT]and secondly by extending the oblique aortic incision into the aortic valve ring or further down into the anterior leaflet of the mitral valve. The sub-and supra-valvular defect will be closed by patch enlargement of the aortic root [PEAR] using autologous pericardium. These techniques allow a considerable enlargement of the valvular ring of about 4 to 10 mm in circumference. In a retrospective study using a computerized program, 847 patients with AVR [1980-1984]were reviewed to evaluate the intraoperative hemodynamic results mainly concerning relief of the transvalvular gradient. In 626 patients AVR was performed, 151 patients had double valve replacement [AVR+MVR], and 70 patients had AVR plus additional surgical procedures. Concentrating on the AVR-group [n=626] there were 103 patients with TSM, 24 patients with PEAR and 20 patients with TSM+PEAR which demonstrated that in a total, of 147 patients of this groups [23.5%] an additional procedure was necessary. The Statistical evaluation of the intraoperative pressure measurements before and after AVR in relation to the size of the implanted prostheses indicated the lowest preoperative mean gradient in patients with AVR alone, the highest in patients who afforded TSM plus PEAR. However, after AVR the mean gradients in all three groups were very low [mean 5 to 10 mmHg]. These data indicate that in patients with a narrow aortic ring and additional considerable ASH, TSM and PEAR are suitable techniques to enlarge the aortic root to enable the implantation of an adequate aortic valve prosthesis. Long-term controls have shown that autologous pericardium is a qualified graft material for the ascending aorta.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.39 no.6
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• pp.263-268
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• 2013

Objectives: The interforminal region, between the mandibular foramen, is known as a relatively safe area that is free of anatomic structures, such as inferior alveolar nerve, submandibular fossa, and lingual side of the mandible is occasionally neglected for its low clinical importance. Even in the case of a severely constricted alveolus, perforation of the lingual cortical bone had been intended. However, anterior extension of the inferior alveolar canal, important anatomic structure, such as concavity of lingual bone, lingual foramina, and lingual canal, has recently been reported through various studies, and untypical bleeding by perforation of the lingual plate on implantation has also been reported. Therefore, in this study, we performed radiographic and statistical analysis on distribution and appearance frequencies of the lingual foramina that causes perforation of the mandibular lingual cortical bone to prevent complications, such as untypical bleeding, during surgical procedure. Materials and Methods: We measured the horizontal length from a midline of the mandible to the lingual foramina, as well as the horizontal length from the alveolar crest to the lingual foramina and from the lingual foramina to the mandibular border by multi-detector computed tomography of 187 patients, who visited Dankook University Dental Hospital for various reasons from January 1, 2008 to August 31, 2012. Results: From a total of 187 human mandibles, 110 (58.8%) mandibles had lingual foramina; 39 (20.9%) had bilateral lingual foramen; 34 (18.2%) had the only left lingual foramen; and 37 (19.8%) had the only right lingual foramen. Conclusion: When there is consistent bleeding during a surgical procedure, clinicians must consider damages on the branches of the sublingual artery, which penetrate the lingual foramina. Also, when there is a lingual foramina larger than 1 mm in diameter on a pre-implantation computed tomography, clinicians must beware of vessel damage. In order to prevent these complications and progress with a safe surgical procedure, a thorough radiographic examination before the surgery is indispensable. Further, clinicians should retract lingual flap definitely to confirm the shape of the lingual bone and existence of the lingual foramina.

• Journal of Periodontal and Implant Science
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• v.27 no.1
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• pp.79-90
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• 1997

The purpose of this study was to evaluate the substantivity of experimentally developed gel type tetracycline HCl and a mixture of tetracycline-citric acid gel, and compare to those of solution type tetracycline HCl. 11 extracted anterior teeth were subjected to this study. After scaling and root planing teeth were randomly divided into 3 treatments groups : group 1; 3 teeth were irrigated with tetracycline HCl(50mg/ml) solution , group 2; tetracycline gel (5%) was inserted in the periodontal pockets of 3 teeth, group 3; a mixture of tetracycline and citric acid gel was inserted in the pockets of 3 teeth. And 2 teeth treated in 0.9 % sterile saline served as controls. After 5-minute exposure, each tooth immediately extracted and incubated at room temperature for 22 days in tris-buffered saline as a desorption media. The total volume of TBS was removed and replaced with fresh TBS, at 24-h intervals. Removed desorption media transferred to a sterile vial and stored at -70 oC. This procedure was repeated every 24 h throughout the 22-day desorption period. Using Porphyromonas gingivalis as an indicator organism, a microtiter assay was used to evaluate antimicrobial activity desorbed from the teeth. 1. 50mg/ml tetracycline HCl solution exhibited the longest antimicrobial activity. Compared to saline treated group, it showed significant difference on the day 1 and day 2 desorption period. 2. The ODs of 5% tetracycline gel and a mixture of tetracycline-citric acid gel were significantly different during the first 24 hour only. 3. There was no statistically significant difference after the day 3 between the groups.(p<0.05). Despite our expectation a mixture of tetracycline-citric acid gel did not show longer antimicrobial activities than those of tetracycline gel, and the solution type exhibited the longest activities. Because the gel type agents may stay in the subgingival environment longer than the solution, if the teeth were not extracted immediately after the delivery of the agent, the result could be different. hus this result suggests the possibilities of practical use of these kind of gel type agents.