• Maxillofacial Plastic and Reconstructive Surgery
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• 제41권
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• pp.29.1-29.10
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• 2019

Background: Reduction in postoperative complications is of vital considerations in impacted third molar teeth surgery. The aim of this study was to compare postoperative complications of impacted third molar surgeries for bone removal using laser, piezoelectric equipment, and conventional rotary instruments. Methods: To address the research purpose, the investigator designed the prospective double-blind clinical trial study. The sample size was determined 20 (40 teeth) by sampling formula in any kind of operation. The data of patients were obtained in the different periods in terms of pain, trismus, swelling, ecchymosis, and patient's satisfaction and then analyzed using SPSS 20 software via paired t test and Wilcoxon and McNemar's tests. Results: The pain immediately after surgery and 2 days and 7 days after surgery was higher in the laser group. The swelling immediately after surgery was more in the laser group but not significant. The amount of mouth opening immediately after surgery and 2 days and 7 days after surgery was significantly lower in the laser group than in the piezosurgery group. The total duration of surgery and duration of osteotomy were significantly longer in the laser group. The patient's satisfaction from surgery with piezosurgery was more than that with laser, but this difference was not significant. Conclusion: Due to the rising demand for impacted wisdom tooth surgery, the present study suggests that hard tissue laser surgery and piezosurgery can clear the future of impacted molar surgery, and these approaches are more efficient in reducing postoperative complications compared to the conventional surgeries.

• Journal of Oral Medicine and Pain
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• 제26권4호
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• pp.395-406
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• 2001

지난 수십년동안, 다양한 레이저기기를 이용하여 치아 경조직에 대한 응용 실험을 수행되었다. 그러나, 발생한 주요한 문제는 열발생과 플라즈마 형성과 같은 부작용이 지속된다는 점이었다. 실망스러운 실험결과에 따라 치아 삭제에 대한 레이저의 응용에 대한 연구가 거의 진행되지 못하였다. 본 연구의 목적은 국내에서 처음으로 개발된 얼비움레이저기기를 사용하여 다양한 에너지 수준과 다양한 펄스빈도에서 법랑질의 삭제율을 비교하고자 하였다. 본 연구에 사용된 레이저기기는 국내에서 최초로 개발된 $2.94{\mu}m$ 펄스를 $250{\mu}s$ 방출하는 얼비움야그레이저 기기이다. 기기의 에너지는 20 mJ에서 350 mJ까지 다양하게 방출하며, 최대 출력은 3.5 W이다. 22개의 치아를 에폭시 레진에 포매하고 경화하였다. 치아의 법랑질을 회전 다이아몬드 칼을 흐르는 물과 함께 사용하여 협측 또는 설측으로 평탄하게 삭제하였다. 제작된 법랑질표면은 6개의 구획으로 구분하여 에너지 수준과 펄스빈도에 따라 조사하였다. 본 연구에서 사용된 표본 수는 132개이며, 삭제율을 조사하기 위한 모든 표본은 22개의 실험 군으로 분류하였다. 실험결과는 다음과 같다. 1. 에너지 수준간에는 유의한 삭제율의 차이가 있었다. 2. 40 및 80 mJ로 조사한 경우에는 펄스빈도 간에 차이가 없었지만, 120 mJ의 출력으로 동일한 에너지를 조사한 경우에는 20 Hz가 40 또는 80 mJ로 조사한 경우 보다 가장 삭제효과가 높았다. 3. 연속조사 한 경우 조사시간 경과에 따라 법랑질의 삭제율은 증가되지 않았다. 결론적으로 효과적으로 법랑질을 삭제하기 위해서는 적절한 에너지와 펄스의 레이저를 사용해야 하며, 또한 항상 정확한 초점거리를 유지해야 할 것으로 사료된다.

• The Journal of Advanced Prosthodontics
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• 제6권6호
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• pp.434-443
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• 2014

PURPOSE. The purpose of this study was to evaluate and compare the effects of different surface pretreatment techniques on the surface roughness and shear bond strength of a new self-adhering flowable composite resin for use with lithium disilicate-reinforced CAD/CAM ceramic material. MATERIALS AND METHODS. A total of one hundred thirty lithium disilicate CAD/CAM ceramic plates with dimensions of $6mm{\times}4mm$ and 3 mm thick were prepared. Specimens were then assigned into five groups (n=26) as follows: untreated control, coating with $30{\mu}m$ silica oxide particles ($Cojet^{TM}$ Sand), 9.6% hydrofluoric acid etching, Er:YAG laser irradiation, and grinding with a high-speed fine diamond bur. A self-adhering flowable composite resin (Vertise Flow) was applied onto the pre-treated ceramic plates using the Ultradent shear bond Teflon mold system. Surface roughness was measured by atomic force microscopy. Shear bond strength test were performed using a universal testing machine at a crosshead speed of 1 mm/min. Surface roughness data were analyzed by one-way ANOVA and the Tukey HSD tests. Shear bond strength test values were analyzed by Kruskal-Wallis and Mann-Whitney U tests at ${\alpha}=.05$. RESULTS. Hydrofluoric acid etching and grinding with high-speed fine diamond bur produced significantly higher surface roughness than the other pretreatment groups (P<.05). Hydrofluoric acid etching and silica coating yielded the highest shear bond strength values (P<.001). CONCLUSION. Self-adhering flowable composite resin used as repair composite resin exhibited very low bond strength irrespective of the surface pretreatments used.

• The Journal of Advanced Prosthodontics
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• 제7권2호
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• pp.108-114
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• 2015

PURPOSE. The aim of this study was to evaluate effect of different surface treatment methods on the bond strength between aged composite-resin core and luting agent. MATERIALS AND METHODS. Seventy-five resin composites and also seventy-five zirconia ceramic discs were prepared. 60 composite samples were exposed to thermal aging (10,000 cycles, 5 to $55^{\circ}C$) and different surface treatment. All specimens were separated into 5 groups (n=15): 1) Intact specimens 2) Thermal aging-air polishing 3) Thermal aging- Er:YAG laser irradiation 4) Thermal aging- acid etching 5) Thermal-aging. All specimens were bonded to the zirconia discs with resin cement and fixed to universal testing machine and bond strength testing loaded to failure with a crosshead speed of 0.5 mm/min. The fractured surface was classified as adhesive failure, cohesive failure and adhesive-cohesive failure. The bond strength data was statistically compared by the Kruskal-Wallis method complemented by the Bonferroni correction Mann-Whitney U test. The probability level for statistical significance was set at ${\alpha}$=.05. RESULTS. Thermal aging and different surface treatment methods have significant effect on the bond strength between composite-resin cores and luting-agent (P<.05). The mean baseline bond strength values ranged between $7.07{\pm}2.11$ and $26.05{\pm}6.53$ N. The highest bond strength of $26.05{\pm}6.53$ N was obtained with Group 3. Group 5 showed the lowest value of bond strength. CONCLUSION. Appropriate surface treatment method should be applied to aged composite resin cores or aged-composites restorations should be replaced for the optimal bond strength and the clinical success.

• Medical Lasers
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• 제8권1호
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• pp.7-12
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• 2019

Background and Objectives Skin and soft tissue defects can be treated according to a range of strategies, such as local flap, skin graft, biological dressing, or free flap. On the other hand, free tissue transfer usually leaves a distinct scar with an inconsistency of color or hypertrophy. This problem is highlighted if the defect is located on the face, which could have devastating effects on a patient's psychosocial health. Materials and Methods The authors used an erbium : yttrium-aluminum-garnet (Er:YAG) laser to resurface the free flap skin and match the color with the surrounding facial skin. This study evaluated the effectiveness of laser skin resurfacing on the harmonious color matching of transferred flap. Patients who had undergone laser resurfacing on facial flap skin between January 2014 and December 2018 were reviewed retrospectively. An ablative 2,940-nm fractional Er:YAG laser treatment was delivered to the entire flap skin at 21 J/cm² with the treatment end-point of pinpoint bleeding. Several months later, the clinical photographs were analyzed. The L^*a^*b^* color co-ordinates of both the flap and surrounding normal skin were measured using Adobe Photoshop. The L^*a^*b^* color difference (ΔE) for the scar and normal surrounding skin were calculated using the following equation: ${\Delta}E=\sqrt{({\Delta}L)^2+({\Delta}a)^2+({\Delta}b)^2}$ Results All five patients were satisfied with the more natural appearance of the flaps. The ΔE values decreased significantly from the pre-treatment mean value of 19.64 to the post-treatment mean value of 11.39 (Wilcoxon signed-rank test, p = 0.043). Conclusion Ablative laser resurfacing can improve the aesthetic outcome of free tissue transfer on the face.

• Journal of the Optical Society of Korea
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• 제7권3호
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• pp.174-179
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• 2003

We construct a four-level system where a metastable state is included in an $Er^{3＋}$ Doped Yttrium aluminum garnet (YAG) crystal. Because of the action of the coherent field, the traditional light amplification with inversion can be exhibited with remarkable variation. As a result, we propose a method to achieve the gain equalization by atomic coherence. At the same time, we find that the high index of refraction accompanied by vanishing absorption can also be reached in this model. We also find that a higher index of refraction with zero absorption can be easily obtained when the coherent field is off resonance.

• 대한치과교정학회지
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• 제43권3호
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• pp.141-146
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• 2013

Objective: Bonding forces of brackets to enamel surfaces may be affected by the procedures used for bleaching and enamel etching. The aim of this study was to investigate the bonding strength of orthodontic brackets to laser-etched surfaces of bleached teeth. Methods: In a nonbleached control group, acid etching (group A) or Er:YAG laser application (group B) was performed prior to bracket bonding (n = 13 in each group). Similar surface treatments were performed at 1 day (groups C and D; n = 13 in each subgroup) or at 3 weeks (groups E and F; n = 13 in each subgroup) after 38% hydrogen peroxide bleaching in another set of teeth. The specimens were debonded after thermocycling. Results: Laser etching of bleached teeth resulted in clinically unacceptable low bonding strength. In the case of acid-etched teeth, waiting for 3 weeks before attachment of brackets to the bleached surfaces resulted in similar, but not identical, bond strength values as those obtained with nonbleached surfaces. However, in the laser-etched groups, the bonding strength after 3 weeks was the same as that for the nonbleached group. Conclusions: When teeth bleached with 38% hydrogen peroxide are meant to be bonded immediately, acid etching is preferable.

• The Journal of Advanced Prosthodontics
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• 제6권1호
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• pp.8-13
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• 2014

PURPOSE. The purpose of this study was to evaluate whether surface treatments affect the translucency of laminate veneers with different shades and thicknesses. MATERIALS AND METHODS. A total of 224 disc-shaped ceramic veneers were prepared from A1, A3, HT (High Translucent) and HO (High Opaque) shades of IPS e.max Press (Ivoclar Vivadent) with 0.5 mm and 1.0 mm thicknesses. The ceramics were divided into four groups for surface treatments. Group C: no surface treatments; Group HF: etched with hydrofluoric acid; Group SB: sandblasted with 50-${\mu}m$ $Al_2O_3$; and Group L; irradiated with an Er;YAG laser. A translucent shade of resin cement (Rely X Veneer, 3M ESPE) was chosen for cementation. The color values of the veneers were measured with a colorimeter and translucency parameter (TP) values were calculated. A three-way ANOVA with interactions for TP values was performed and Bonferroni tests were used when appropriate (${\alpha}=0.05$). RESULTS. There were significant interactions between the surface treatments, ceramic shades and thicknesses (P=.001). For the 0.5-mm-thick specimens there were significant differences after the SB and L treatments. There was no significant difference between the HF and C treatments for any shades or thicknesses (P>.05). For the 1-mm-thick ceramics, there was only a significant difference between the L and C treatments for the HT shade ceramics (P=.01). There were also significant differences between the SB and C treatments except not for the HO shades (P=.768). CONCLUSION. The SB and L treatments caused laminate veneers to become more opaque; however, HF treatment did not affect the TP values. When the laminate veneers were thinner, both the shade of the ceramic and the SB and laser treatments had a greater effect on the TP values.

• 대한소아치과학회지
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• 제31권4호
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• pp.569-578
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• 2004

본 연구는 유치열과 영구치열에서 구개의 길이, 폭, 깊이 및 치열궁의 형태 등을 조사하여 남녀간의 차이와 유치열과 영구치열간의 변화양상을 파악하는 것이다. 유치열기 아동 100명과 영구치열기 성인 100명 총 200명을 대상으로 하여 상악 석고 모형을 채득하고 3차원 laser scanner(SD Scanner, DS4060, LDI, U.S.A.)를 통한 석고 모델의 측정을 통해 cloud data, polygonization, section curve and loft surface, fit and horizontal plane (Surfacer 10.0. Imageware, U.S.A.)을 기초로 하여 구개의 폭, 길이, 높이 및 치열궁의 형태 등을 계측하였다. 통계학적 분석을 위해 t-tests가 사용되었다. 이에 다음과 같은 결론을 얻었다. 1. 구개의 계측항목에서 유치열 전방부 구개높이를 제외한 나머지 항목에서 남자가 여자보다 크게 나왔으며, 유치열은 전구개폭(p<0.05)과 후구개폭(p<0.01), 영구치열은 구개폭(p<0.05)과 전구개길이(p<0.01), 중구개, 후구개길이(p<0.05)에서 남녀간에 유의한 차이가 있었다. 2. 남녀의 구개지수에서 유치열에서는 구개장고지수(p<0.05)와 구개장폭지수(p<0.01)가 남녀간에 통계학적으로 유의한 차이가 있었다. 영구치열의 구개지수에서는 남녀간에 유의한 차이가 없었다. 3. 유치열과 영구치열의 계측항목 비교에서 후방부 구개폭이 가장 많이 증가하였으며, 다음으로 후방부 구개높이, 전방부 구개폭, 전방부 구개길이 순이었다. 전방부 구개높이와 후방부 구개길이는 오히려 감소하였다. 4. 유치열과 영구치열의 구개지수 비교에서 구개장고지수와 구개장폭지수, 후구개폭고지수는 영구치열에서 증가하였고, 나머지 지수는 감소하였다.보아 Er:YAG 레이저와 Chinese ink로 photosensitization을 시행한 후의 Nd:YAG 레이저 조사는 일정시간 동안 S. mutans의 증식과 산 생성능을 억제시키므로써 치아우식증 예방효과를 얻을 수 있다고 사료되나 억제효과가 오래가지 않아 임상적으로 효과를 얻기 위해서는 자주 조사를 해주어야 한다는 문제점을 안고 있어 임상적으로 치아우식증 예방이란 단독 목적으로 사용하기에는 실용성이 크지 않다고 사료된다.전자현미경 관찰에서 초음파 진동을 가한 군에서 resin tag의 길이가 길었고, lateral branch의 수도 많이 관찰되었다.TEX>$1\rightarrow6$ 결합이 주된 결합인 수용성 글루캔이었다. 이상의 결과를 종합하면 구강에서 분리된 Streptococcus salivarius 119에 의한 Streptococcus mutans의 인공치태 형성 억제작용은 수용성 글루캔 형성에 의한 것으로 사료되었다.동을 유도할 수 있다고 사료된다. 또한 이유식을 통한 다양한 식품의 경험 및 식품 섭취방법 등을 연습하는 과정을 통해 앞으로의 식생활 및 성장 발달에 영향을 미칠 것으로 사료된다. 따라서 영유아의 성장발달에 따른 적절한 영양교육의 실시가 보다 체계적으로 활성화 되어야 하겠으며 이를 위해 실제로 도움이 될 수 있는 구체적인 교육내용, 방법 및 도구의 개발이 요구된다.어서, B군은 A군,C군,D군과 비교하여 통계학적으로 유의성 있는 차이를 보였고(p<0.05), E군은 F군,G군과 비교하여 통계학적으로 유의성 있는 차이를 보였다(p<0.05). 3. 광중합형 및 자가중합형 교정용 전색제는 법랑질탈회 예방효과가 있었다. 4. 광중합형 및 자가중합형 교정용 전색제는 법랑질탈회 진행억제효과가 있었다. 5. 광중합형 및 자가중합형 교정용 전색제 표본에