• Journal of Periodontal and Implant Science
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• 제32권2호
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• pp.315-324
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• 2002

The purpose of this in vitro study was to evaluate the efficiency of Er:YAG laser on calculus removal and the morphologic changes and hardness of the irradiated surface at different power settings. This experiment used human teeth which were extracted due to periodontal disease and had a band of calculus. Forty root slabs ($5{\times}5mm$) were made and divided into control group and irradiated groups. Experimental groups were as follows; Control group (root planing), Group1 (irradiated with laser at 30mJ), Group2 (irradiated with laser at 60mJ), Group3 (irradiated with laser at 100mJ). Twelve root slab embedded in resin block were used in each group. Er:YAG laser was applied under water irrigation with the tip held perpendicular to the root surface in contact mode. The treatment time was measured until the calculus was removed completely under naked eyes. The efficiency of calculus removal was evaluated by the time for removal. Morphological changes of laser irradiated site were observed under SEM and the surface hardness was measured using a VH tester. The results were as follows; 1. The efficiency of laser scaling was increased with increasing the energy level of irradiation(p<0.05). 2. The morphological changes such as carbonization, crater and scale-like defects in the irradiated root surface were frequently observed with increasing the energy level. 3. The surface hardness tended to increase at 60mJ and 100mJ irradiated groups than that of control group. From the results evaluting on the efficiency, morphological change and surface hardness, lower energy level was suggested for the clinical application of the Er:YAG laser in scaling.

• 대한기계학회논문집B
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• 제41권7호
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• pp.463-468
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• 2017

경피를 통한 약물 전달 방식에 있어, 본 연구에서 제안하고 있는 바늘 없는 주사기 시스템은 레이저와 마이크로젯 인젝터로 구성 되어 있다. 이때 마이크로젯 인젝터의 핵심 메커니즘은 레이저 유도버블이다. 동력원으로 Nd:YAG와 Er:YAG, 두 종류의 레이저가 사용되었다. 버블의 특성을 결정짓는 레이저 변수인 펄스폭, 파장 등이 본 연구에서 고려되었다. Nd:YAG 레이저의 경우에 펄스폭이 버블의 생존 시간보다 짧기 때문에 캐비테이션에 가까운 버블을 형성하는 반면 Er:YAG 레이저의 경우에 펄스폭이 상대적으로 길고 물에서의 흡수가 잘 되기 때문에 보일링 버블이 만들게 된다. 버블 및 마이크로젯의 자세한 움직임은 초고속 카메라를 통해 촬영되었다. 이와 같은 과정을 통하여 마이크로젯의 특성이 버블에 의해 결정되는 것을 본 연구를 통해 관찰되었다. 약물 전달 성능은 기니어피그 조직에 형광물질을 침투한 결과로 부터 분석하였다.

• Journal of the Optical Society of Korea
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• 제17권1호
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• pp.5-9
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• 2013

We report on high-power continuous-wave operations of an Er:YAG ceramic laser in-band pumped by a cladding-pumped Er,Yb fiber laser at 1532 nm. With an output coupler of 10% transmission, the ceramic laser yielded 16.7 W of continuous-wave output at 1645 nm for 28.8 W of incident pump power, corresponding to a slope efficiency of 61.0% with respect to the incident pump power. The lasing wavelength switched to 1617 nm when output couplers of > 20% transmission were used. Up to 16.2 W of 1617 nm output was generated for 33.0 W of incident pump power, corresponding to a slope efficiency of 51.8%. Graphene Q-switched operation of Er:YAG cermic laser at 1645 nm was also demonstrated with stable pulses of 30-74 kHz repetition rates and 1.5-6.4 ${\mu}s$ pulse widths.

• Medical Lasers
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• 제9권1호
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• pp.76-78
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• 2020

Verruca plana is a cutaneous infection caused by the human papilloma virus. Although various treatment methods are currently available, most have limitations due to the risk of complications such as hyperpigmentation, edema, and scarring. Moreover, as the infection tends to spread easily, new verrucae can potentially develop, and treatment procedure times tend to be lengthy. Thus, novel treatment methods are required. The 2790-nm wavelength erbium:yttrium-scandium-gallium-garnet (Er:YSGG) laser is a superficial resurfacing laser. Here, we present a case of a 25-year-old woman with multiple verrucae treated using a 2790-nm Er:YSGG laser. Compared to traditional methods, this novel laser is convenient, produces better cosmetic outcomes, and is less time-consuming; it is therefore suitable for the treatment of facial verruca plana.

• 대한치과보철학회지
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• 제37권2호
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• pp.256-268
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• 1999

Submerged implants require secondary surgical uncovering of implants after healing period of 3-6 months. In surgical methods, there are surgical scalpel, tissue punch, electro-surgical, and laser-used uncovering, and so forth The objectives of this study are investigation and assessment of 1) thermal change in clinical application for uncovering of HA-coated implant and pure titanium implant irradiated by pulsed Nd-YAG, $CO_2$, and Er-YAG laser. 2) surface change of cover screws aaer irradiation using laser energy. The temperature of apex & side wall of implants were recorded at 10sec, 20sec, 30sec after 30sec irradiation to implant healing screw; 1) pulsed Nd-YAG laser; 2W, 20pps, contact mode 2) $CO_2$ laser; water-infused & non-water infused state, 2.5-3.5W, contibuous mode, noncontact mode 3) $CO_2$ laser ; non-water infused state, 3W, superpulse, noncontact. mode 4) Er-YAG laser; (1) non-water infused state, 10pps, 60mj, contact mode (2) water-infused state, 10pps, 60mj, 80mj, 101mj, contact mode. According to the results of this study, pulsed Nd-YAG laser is not indicated because of increased thermal change and pitting of metal surface of implant cover screw. By contrast, $CO_2$ laser & Er-YAG laser are presumed to indicate because of narrow range of thermal change & near abscence of thermal damage of metal surface. Dental laser is thought to be much helpful to surgical procedure when it is used as optimal power and time condition considering characteristics and indications of each laser. Further research is needed to verify that these techniques are safe and beneficial to implant success.

• 대한소아치과학회지
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• 제30권3호
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• pp.439-447
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• 2003

레이저의 구강내 산 생성 세균인 S. mutans에 대한 증식 및 기능 억제효과를 평가하기 위하여 S. mutans KCTC 3065가 포함된 세균 pellet에 Er:YAG 레이저와 Nd:YAG 레이저를 비접촉식 방법으로, 조사세기 50mJ, 조사시간 5초, 그리고 pulse repetition rate를 각각 10Hz와 30Hz로 하여 조사하고 세균 군락수, 산 생성능, 불용성 세포외다당류의 합성량을 측정하여 다음과 같은 결과를 얻었다. 1. Chinese ink로 photosensitization을 시행한 후 Nd:YAG 레이저를 조사한 경우가 S. mutans의 증식을 가장 많이 억제하였으며 Er:YAG 레이저 조사도 증식을 억제하였다. 그러나 Chinese ink를 사용하지 않고 Nd:YAG 레이저를 단독으로 조사한 경우는 S. mutans의 증식을 억제하지 못하였다. 레이저 조사조건 중 pulse repetition rate는 전반적으로 세균 증식 억제에 영향을 미치지 못하였다. 2. Chinese ink로 photosensitization을 시행한 후 Nd:YAG 레이저를 조사한 경우가 일정기간 동안 S. mutans의 산생성능을 가장 많이 억제하였으며 Er:YAG 레이저 조사도 산 생성능을 억제하였다. Chinese ink를 사용하지 않고 Nd:YAG 레이저를 단독으로 조사한 경우는 S. mutans의 산생성능을 억제하지 못하였다 Er:YAG 레이저와 Chinese ink로 photosensitization을 시행한 후 Nd:YAG 레이저를 조사한 경우는 pulse repetition rate가 클수록 전반적으로 세균의 산생성능을 더 많이 억제하였다. 3. 레이저 조사는 S. mutans의 불용성 세포외다당류의 합성에 영향을 미치지 못하였다. 이상의 결과로 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.

• Journal of Periodontal and Implant Science
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• 제41권5호
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• pp.234-241
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• 2011

Purpose: One of the most frequent complications related to dental implants is peri-implantitis, and the characteristics of implant surfaces are closely related to the progression and resolution of inflammation. Therefore, a technical modality that can effectively detoxify the implant surface without modification to the surface is needed. The purpose of this study was to evaluate the effect of erbium-doped: yttrium, aluminium and garnet (Er:YAG) laser irradiation on the microstructural changes in double acid-etched implant surfaces according to the laser energy and the application duration. Methods: The implant surface was irradiated using an Er:YAG laser with different application energy levels (100 mJ/pulse, 140 mJ/pulse, and 180 mJ/pulse) and time periods (1 minute, 1.5 minutes, and 2 minutes). We then examined the change in surface roughness value and microstructure. Results: In a scanning electron microscopy evaluation, the double acid-etched implant surface was not altered by Er:YAG laser irradiation under the condition of 100 mJ/pulse at 10 Hz for any of the irradiation times. However, we investigated the reduced sharpness of the specific ridge microstructure that resulted under the 140 mJ/pulse and 180 mJ/pulse conditions. The reduction in sharpness became more severe as laser energy and application duration increased. In the roughness measurement, the double acid-etched implants showed a low roughness value on the valley area before the laser irradiation. Under all experimental conditions, Er:YAG laser irradiation led to a minor decrease in surface roughness, which was not statistically significant. Conclusions: The recommended application settings for Er:YAG laser irradiation on double acid-etched implant surface is less than a 100 mJ/pulse at 10 Hz, and for less than two minutes in order to detoxify the implant surface without causing surface modification.

• 대한의용생체공학회:의공학회지
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• 제20권2호
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• pp.231-236
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• 1999

Q-switch된 Er:YAG 레이저를 이용해서 치아표면에 뿜어준 외부의 물로 인해 유도된 열 및 역학적인 효과를 이해하는 것은 free-running Er:YAG 레이저에 의한 절삭효과를 이해하는데 대단히 중요하다. 이는 (파장 하나의 길이가 250 $\mu\textrm{s}$인) free-running 레이저에 의한 한 거 대효과가 본 실험에서 이용한 (파장 하나의 길이가 1 $\mu\textrm{s}$인) Q-switch된 레이저에 의한 미소효과들의 축적이기 때문이다. 치아표면에 물이 있을 때 Q-Switch된 레이저에 의한 절삭률은 그렇치 않은 때에 비해 증가되었다. 치아표면에 물을 뿜어주는 횟수는 절삭률에 영향을 미쳐서 저에너지에서는 더디게 물을 뿜어줄때 놀은 절삭률을 얻었다. 반동압력의 세기는 치아표면 조건에 의존하는데. 표면이 젖을수록 그리고 뿜어준 물의 양이 증가 할 수록, 반동압력의 세기 또한 증가하였다. 이 연구로부터 우리는 1-$\mu\textrm{s}$-길이의 pulsed 레이저에 의해 유도된 열 및 역학적인 효과가 외부에 물이 있을 때 free-running Er:YAG 레이저에 의한 절삭을 이해하는데 중요한 정보를 제공해 준다는 것을 알았다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.380-384
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• 1997

This study was performed to understand the exogenous-water-drop induced thermomechanical effect on the tooth in the free-running Er:YAG laser mode for the proper use of water as a laser energy absorber and coolant in dentistry. The ree-running Er:YAG laser was used in the dental hard tissue ablation study. A Microjet system was employed to dispense precise water drops. Ablation rate, recoil momentum, and temperature rise in the pulp cavity were measured with and without an exogenous water drop on the tooth surface. Exogenous water enhanced ablation rate in the thick tooth in which the ablation rate on the dry surface does not increase linearly but shows plateau. Optimal exogenous water volume was shifted from 2 nl to 4 nl as the laser energy was increased from 48 mJ to 145 mJ. The magnitude of the recoil momentum was increased as the volume of exogenous water increased. The results of this study suggest that we must pay attention to the recoil momentum or recoil pressure study or the optimal and safe usage of water in the dental treatment because these mechanical effects depend on the volume of exogenous water on the tooth surface.

• Current Optics and Photonics
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• 제3권2호
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• pp.135-142
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• 2019

We report the precipitation of ZnO nanocrystals, Ag-clusters, and Ag nanoparticles in Ag/Er/Yb doped borate glasses by furnace annealing and $CO_2$ laser annealing. The XRD analysis revealed the precipitation of ZnO and Ag phases. The absorption spectra, the TEM and energy dispersive spectroscopy (EDS) revealed the incorporation of Er and Yb ions into ZnO nanocrystals formed by a laser technique and showed the surface plasmon band of Ag nanoparticles. The down-converted blue emission intensity of $Er^{3+}$ ions obtained under 365 nm excitation was enhanced by more than a hundred times in the glass treated by furnace annealing, mainly due to the energy transfer from Ag-clusters. Moreover, we discussed the contribution of Ag nanoparticles and defects to emission characteristics in the glasses treated by two annealing techniques. Up-conversion emissions of the $Er^{3+}$ ions under 980 nm excitation were enhanced due to the incorporation of $Er^{3+}$ and $Yb^{3+}$ ions into ZnO nanocrystals after thermal treatments.