• 대한치과보철학회지
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• 제46권3호
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• pp.255-260
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• 2008

STATEMENT OF PROBLEM: Preparation of implant beds with lasers is considered a safe and reliable method, but the accuracy of this technique has not been examined. PURPOSE: The purpose of this study was to evaluate the accuracy and effectiveness of implant bed preparation using an Er,Cr:YSGG laser. MATERIAL AND METHODS: An Er,Cr:YSGG laser was applied to pig rib bone. The laser was employed at a 5.75 W power setting, 30 Hz/sec pulse repetition, and 70 ${\mu}s$ pulse duration with 50 % water and 60% air spray. According to laser tips the groups were divided as follows; Group 1: paralleled - shaped sapphire tip (0.6 mm${\Phi}$), Group 2: paralleled - shaped zirconia tip (0.6 mm${\Phi}$), Group 3: tapered sapphire tip (0.4 mm${\Phi}$). The Er,Cr:YSGG laser tip was separated by 1 mm from the bone and applied for 15 seconds in a non-contact mode. After the application, the bone was sectioned for specimens. Histologic measurements were determined by computerized morphometry. The length of the prepared bone surface was measured and the width of the entrance was measured. The results were analyzed with one-way ANOVA (P<0.05). RESULTS: The prepared length of group 3 was longer than that of group 2. The prepared bone width was larger than the width of the laser tip in every group. Additional bone removal was observed adjacent to the prepared area and displayed an irregular surface. CONCLUSION & DISCUSSION: Different cutting effects were observed according to the laser tip, emphasizing the importance of proper tip selection in the clinical setting. This preliminary study supported the existence of hydrokinetic effects.

• 대한소아치과학회지
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• 제45권2호
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• pp.154-161
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• 2018

진정작용은 행동조절이 어렵고 광범위한 치료가 필요하거나 의학적 문제가 있는 어린이의 치과 치료에 유용한 행동조절 방식이다. 본 연구의 주된 목적은 연세대학교 치과대학병원 소아치과에서 사용하는 진정제와 진정치료의 경향을 분석하여 진정법의 사용의 변화를 살펴보는데 있다. 본 연구는 2011년 - 2016년까지 연세대학교 치과대학병원 소아치과의 전자의무기록(EMR)을 바탕으로 환자 및 진정법을 검토하였다. 연구 결과에 따르면, 진정법으로 치료받은 환자들의 수가 일반적으로 증가했다. 남자가 여자보다 진정법을 이용한 치과 치료를 더 많이 받았으나 2015년부터는 유사한 비율로 적용되고 있다. 전신질환(ASA II) 환자의 치료 비율은 2013년에 감소했지만, 이후에는 일정하게 유지되었다. 4 - 5세 및 6 - 10세의 진정 치료 비율은 일반적으로 증가하는 반면, 0 - 2세 및 11세 이상은 감소했다. 3세는 비교적 일정한 비율로 유지되고 있다. 가장 자주 사용되는 진정법은 아산화질소 흡입진정법이었으며, chloral hydrate의 사용이 감소하는 동안 benzodiazepine계열의 사용이 증가했다. 최근에는 행동관리 기법으로 진정법이 확대되고 있다. 그러나 안전한 사용을 위하여 다차원적 접근이 요구되고 있으며, 진정제 사용의 안전성과 효능에 대한 추가 연구 역시 동반 수행되어야 한다.

• 대한치과교정학회지
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• 제30권3호
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• pp.335-342
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• 2000

본 연구의 목적은 chlorhexidine varnish를 고정식 교정장치 장착 환자의 치면에 도포한 후 나타나는 치태내 균주의 변화 양상을 장기간 관찰하는 것이다. 서울대학교병원 치과진료부 교정과에서 고정치 교정장치로 치료하기로 하였던 환자 100명중에서 32주까지 장기간 추적 (follow-up) 되었던 21명을 최종 연구대상으로 선정하였다. 실험군 (12명) 은 chlorhexidine varnish를 1주일 간격으로 4회 도포한 후 고정식 교정장치를 부착하였고, 대조군 (9명) chlorhexidine varnish 처치를 하지 않고 고정식 교정장치를 부착하였다. 그리고 실험군에서는 20주 째에 chlorhexidine varnish를 1회 처치하였다. 두 군에서 고정식 교정장치 부착 직전과 부착 후 4, 8, 20, 32주의 치태내 균주의 변화 양상을 간접면역 형광 현미경법으로 분석하고 SAS 통계프로그램을 사용하여 다음과 같은 결과를 얻었다. 1. Streptococcus mutans는 실험군에서 전 실험기간동안 통계학적으로 유의성 있게 억제되 었고 (p<0.01), 대조군에서 전 실험기간동안 통계학적으로 유의성 있게 증가하였다 (p<0.05). 2. Streptococcus sanguis, Streptococcus mitis, Actinomyces viscosus, Actinomyces naeslundii는 실험군과 대조군에서 통계학적으로 유의성 있는 변화를 보이지 않았다. 따라서 고정식 교정장치를 사용할 환자에서 chlorhexidine varnish를 처치할 경우 치아 우식의 주 원인균인 Streptococcus mutant를 장기간 선택적으로 억제할 수 있을 것으로 생각된다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제44권5호
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• pp.225-231
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• 2018

Objectives: The purpose of this study was to investigate the demographic and clinical characteristics of patients with medication-related osteonecrosis of the jaw (MRONJ) and to elucidate factors affecting recurrence in surgical treatment. Materials and Methods: A total of 51 patients who were diagnosed with MRONJ were analyzed according to demographic and clinical features and treatment results through a retrospective chart review from 2013 to 2017 in the Department of Oral and Maxillofacial Surgery, Korea University Anam Hospital, Seoul in Korea. Results: Alendronate composed the majority of medication doses (55.6%), followed by ibandronate (20.0%), risedronate (15.6%), and zoledronate (6.7%). Forty patients (88.9%) were given oral medication, and five patients (11.1%) were intravenously treated, and the mean duration of medication use was $61.1{\pm}42.9$ months. A total of 10 patients (22.2%) had a drug holiday before MRONJ-induced dental treatment lasting an average of $6.8{\pm}7.0$ months. MRONJ occurred 2.7 times more in the mandible, with 41 cases (73.2%) occurring in the mandible and 15 cases (26.8%) occurring in the maxilla, and the prevalence of affected posterior parts (premolar-molar) was six times greater than that of the anterior parts (incisor-canine) (48 cases vs 8 cases, 85.7% vs 14.3%). The most common dental cause of MRONJ was tooth extraction (69.6%). Regarding recurrence, there was no statistical difference in recurrence rate according to either site or stage. However, recurrence occurred in 4 out of 34 cases (11.8%) in the primary closure group and 9 out of 20 cases (45.0%) in the secondary healing group, and there was a statistical difference with respect to closure technique. Conclusion: The identified risk factors in patients taking bone resorption inhibitors can aid dental clinicians in ensuring prevention and proper treatment of MRONJ.

• 한국콘텐츠학회논문지
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• 제11권11호
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• pp.264-273
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• 2011

본 연구는 노년인구의 증가에 따른 치아상실로 매년 증가하고 있는 임플란트 치료에 있어 대상 환자가 치료를 결정하는데 영향을 미치는 요인을 분석하여 긍정적인 인식 전환과 임상적 기준 마련에 관한 기초자료를 제공하는데 있다. 2010년 7월부터 약 3개월간 서울시와 경기도 소재의 13개 치과 의료기관의 환자 217명을 대상으로 임플란트 치료군과 비치료군으로 구분하여 설문조사를 시행하였다. 임플란트 치료군은 50대(30.3%)가, 비치료군은 20대(35.7%)가 가장 높았고, 치료군 환자의 구강관리가 양호하였으며, 긍정적인 태도를 보였다. 다중로지스틱 회귀분석으로 분석한 결과, 임플란트 치료결정에 영향을 미치는 요인은 연령, 성별, 교육기간, 월 소득, 치주조직상태, 정기검진여부, 상담태도, 병원신뢰도 등으로 나타났다. 따라서 예방적 차원의 정기적인 구강검진과 관리의 필요성에 대한 교육 및 홍보가 필요하며, 임플란트 치료결정에 긍정적인 인식을 가질 수 있도록 의료진의 상담 기술을 키우고 병원의 신뢰도 향상을 위한 다각도의 노력이 필요하다. 아울러 임플란트 치료 결정에 환자의 막연한 주관적 판단보다는 결정을 용이하게 할 수 있는 명확한 임상적 기준 마련이 필요하며, 비용 부담없이 임플란트 치료를 받을 수 있도록 정부 차원의 재정적 지원이나 정책적인 대안이 요구된다.

• Journal of Periodontal and Implant Science
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• 제27권1호
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• pp.117-128
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• 1997

Using barrier membrane, guided bone regeneration(GBR) and guided tissue regeneration(GTR) of periodontal tissue are now widely studied and good results were reported. In bone regeneration, not all cases gained good results and in some cases using GTR, bone were less regenerated than that of control. The purpose of this study is to search for the method to improve the success rate of GBR and GTR by examination of the cause of the failure. For these study, rats and beagle dogs were used. In rat study, 5mm diameter round hole was made on parietal bone of the rat and 10mm diameter of bioresorbable membrane was placed on the bone defects and sutured. In 1 ,2, 4 weeks later, the rats were sacrificed and Masson-Trichrome staining was done and inspected under light microscope for guided bone regeneration. In dog study, $3{\times}4mm^2$ Grade III furcation defect was made at the 3rd and 1th premolar on mandible of 6 beagle dogs. The defects were covered by bioresorbable membrane extending 2-3mm from the defect margin. The membrane was sutured and buccal flap was covered the defect perfectly. In 2, 4. 8 weeks later. the animals were sacrificed and undecalcified specimens were made and stained by multiple staining method. In rats. there was much amount of new bone formation at 2 weeks. and in 4 weeks specimen, bony defect was perfectly dosed and plenty amount of new bone marrow was developed. In some cases, there were failures of guided bone regeneration. In beagle dogs, guided tissue regeneration was incomplete when the defect was collapsed by the membrane itself and when the rate of resorption was so rapid than expected. The cause of the failure in GBR and GTR procedure is that 1) the membrane was not tightly seal the bony defects. If the sealing was not perfect, fibrous connective tissue infiltrate into the defect and inhibit the new bone formation and regeneration. 2) the membrane was too tightly attached to the tissue and then there was no space to be regenerated. In conclusion, the requirements of the membrane for periodontal tissue and bone regeneration are the biocompatibility, degree of sealingness, malleability. space making and manipulation. In this animal study. space making for new bone and periodontal ligament, and sealing the space might be the most important point for successful accomplishment of GBR and GTR.

• 치위생과학회지
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• 제15권1호
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• pp.54-59
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• 2015

본 연구는 시중에 널리 사용되는 치과용 지르코니아 코어를 이용하여 서로 다른 형태의 지대치를 대상으로 작업모형을 제작한 후, 치과용 스캐너를 통해 3차원 디지털 모형을 전환한 데이터를 토대로 지르코니아 코어를 제작하였으며, 각 실험군별 변연 적합도를 측정하여 비교분석하고자 하였다. 이와 같은 결과로 형태가 다른 지대치가 CAD/CAM system으로 치과 보철물 제작 시 적합도의 영향여부를 비교하였다. 제한된 조건 하에서 수행된 본 연구에서 다름과 같은 결과를 보였다. 지대치의 형태가 다른 작업모형으로 제작된 지르코니아 코어의 변연 적합도는 큰 차이가 없었다(p>0.05). 작업모형의 부위를 4등분으로 나누어 측정한 변연 적합도 또한 통계적으로 유의한 차이를 보이지 않았다. 결론적으로 3종류의 다른 지대치 모두 유사한 지르코니아 코어의 변연 적합도를 보였으며, 측정된 결과는 선행연구에 비추어 볼 때 임상적으로 허용 가능한 수치($100{\sim}120{\mu}m$)를 초과하는 실험군은 없었다. 이와 같은 결과를 토대로 다른 형태의 지대치를 사용하여 제작되었더라도 지르코니아 코어의 변연 적합도에 큰 영향을 주지 않을 것으로 생각된다.

• 대한치과보철학회지
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• 제39권3호
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• pp.260-272
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• 2001

All-ceramic restorations have had a more limited life expectancy than metal ceramic restorations because of their low strength. Their relatively lower strength and resistance to fracture have restricted the use of all-ceramic crowns to anterior applications where occlusal loads are lower. But there has been increasing interest in all-ceramic restorations because patients are primarily concerned with improved esthetics. Many efforts have been made to in prove the mechanical properties of dental ceramics. This study was designed to elucidate the influence of the luting agent on the strength of the Empress 2 crown (staining technique) cemented on human teeth. Seventy extracted human permanent molar teeth were chosen. Teeth were prepared for Empress 2 crowns with milling machine on a surveyor. A dental bur was placed in the mandrel that was positioned so that the long axis of the bur was perpendicular to the surveyor base. Dimensions of the Empress 2 crown preparation were $6^{\circ}$ taper on each side, $1.5{\pm}0.1mm$ shoulder margin, and 4mm crown height. The luting cements used in this study were as follow: 1. Uncemented 2. Zinc phosphate cements (Confi-Dental) 3. Conventional glass ionomer cement : Fuji 1 (GC) 4. Resin-modified glass ionomer cements : Fuji plus (GC) 5. Adhesive cements : Panavia F (Kuralay), Variolink II (Vivadent), Choice (Bisco). Fracture test using Instron. The crowns were loaded in compressive force to evaluate the effect of these cements on the breaking strength of these all-ceramic crowns. A steel ball with a diameter of 4mm was placed on the occlusal surface and load was applied to the steel ball by a cylindrical bolt with a crosshead speed of 0.5mm per minute until fracture occurred. The fractured surface was examined using Scanning Electron Microscopic Image (SEM) to discover the correlation between fracture strength and bonding capacity. Within the limitation of this in vitro study design, the results were as follows : 1. fomentations significantly increased the fracture resistance of Empress ceramic crowns compared to control. Uncemented (206.9 N): ZPC (812.9 N): Fuji 1 (879.5 N): Fuji Plus (937.7 N): Choice (1105.4 N): Variolink II (1221.1 N): Panavia F (1445.2 N). 2. Resin luting agent, treated by a silane bond enhancing agents, yielded a significant increase in fracture resistance. In some of the Panavia F group, a fracture extended into dentin. 3. According to SEM images of fractured Empress crowns, the stronger the bond at both interfaces(crown and die), the more fracture strength was acquired.

• 대한치과보철학회지
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• 제43권2호
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• pp.264-279
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• 2005

Statement of problem. Intraoral corrosion not only affects the esthetic and function of metallic dental restoration, but also has biologic consequences as well. Therefore, corrosion is considered a primary factor when choosing the dental alloy and laboratory technique. Purpose. The objective of this study was to compare the effects of solder and laser weld on corrosion Material and methods. Test specimens were made of 2 types of gold alloys, Co-Cr and Ni-Cr alloy and fabricated 3 methods, respectively: as cast, solder, and laser weld. For the analysis of corroding properties, potentiodynamic polarization test and immersion test conducted. The potentiodynamic polarization scan curve were recorded in 0.9% NaCl solution(pH 7) using Potentiostat/Galyanostat Model 273A. All specimens were exposed to 0.9% NaCl solution(pH 2.3) during 14 days. Elemental release into corrosive solution was measured by atomic emission spectrometry Differences in corrosion potential and mass release were determined using ANOVA. Results and conclusion. Through analyses of the data, following results were obtained. 1. In Pontor MPF and Wiron 99, corrosion potential of the solder group was statistically lower than as cast and laser weld group (p<0.05) , but there was no difference between corrosion potential of solder group and laser weld group in Pontor MPF and no differences between as cast and laser weld group (p>0.05). In Jel-Bios 10 and Wirobond, there was no difference of corrosion potential according to joining methods(p>0.05). 2. In all tested alloys, the amount of released metallic ion was greatest in the solder group(p<0.05). There was no difference between as cast group and laser weld group in Jel-Bios 10 and Wirobond(p>0.05). 3. In scanning electron microscopic examination. except soldered Wiron 99 specimens, it is impossible to discriminate the corrosive property of solder and laser weld. 4. Under the this experimental circumstances, laser weld appears superior to the solder when corrosion is considered.

• 대한소아치과학회지
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• 제23권4호
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• pp.788-799
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• 1996

The purpose of this study was to determine the accuracy of the prediction methods which are frequently used in the clinic, such as Moyers', Tanaka and Johnston's, Song's Hixon and Oldfather's, Kaplan's, Smith's. These prediction methods were compared to the data, which were obtained from 100 Kyung-Hee University students (50 males and 50 females) with normal occlusion of permanent dentition, using a retrospective statistical analysis. The standard periapical radiopgraphs for the lower premolars using 16-inch long cone technique and the yellow stone dental casts were taken from each samples. The mesiodistal widths of 4 incisors, canine, premolars were measured on the dental casts, and those of premolars were measured on the radiographs. The correlation coefficients, paired samples t-tests, regression coefficients between the actual measuredments of the samples and the predicted measurements of each methods were analyzed. The results obtained were as follows: 1. The prediction methods using periapical radiographs tended to show a stronger correlation than the methods using dental casts; the correlation coefficients between the actual widths of the lower canine and premolars and the predicted widths of the tested methods were higher in Smith, Kaplan, Hixon & Oldfater, and Tanaka & Johnston (p<0.001). 2. The Moyers' probability chart at 65 % showed a tendency toward the least difference between the actual measurements and the predicted widths of the lower canine and the premolars, and the methods of Smith, Kaplan, Tanaka & Johnston also showed a less difference. 3. By means of evaluation in correlation coefficients and paired smaples t-tests, the Smith and Tanaka & Johnston in male, and the Moyers' 65 % and Song in female showed a high tendency toward accurate methods. 4. The regression equations by models that are derived from the study were as follows: Male(Lt.) :Y=10.799+0.475X Femle(Lt.) :Y= 7.427+0.609X (Rt.) :Y=11.043+0.462X (Rt.) :Y= 8.475+0.556X 5. The regression equations by radiographs that are dericed from the study were as follows: Male(Lt.) :Y=6.5651+0.9720X Femle(Lt.) :Y=4.8656+1.0632X (Rt.) :Y=7.8610+0.9060X (Rt.) :Y=4.5483+1.0843X