• Journal of Photoscience
• /
• 제5권1호
• /
• pp.33-37
• /
• 1998

One macroscopic effect in the free-running Er:YAG laser is an accumulation of microscopic effects. Understanding of the exogenous water induced mechanical effect on the dental hard tissue by the Qswitched Er:YAG laser has an important impact on the further understanding of the free-running Er:YAG laser ablation on the dental hard tissue. The Q-switched Er:YAG laser (1-$\mu$s-long pulse width) was used in the recoil pressure measurement with an aid of water-jet system and a pressure transducer. The amplitude of the recoil pressure depends on the tooth surface conditions (dry and wet) and the volume of the water upon it. Wet surfaces yielded higher recoil pressure than that of dry, surface, and as the volume of the exogenous water drop increased, the amplitude of the recoil pressure increased also.

• Journal of Periodontal and Implant Science
• /
• 제32권2호
• /
• pp.303-314
• /
• 2002

This study was performed to evaluate the usability of Er:YAG laser for periodontal therapy. Forty dental root slabs ($5{\times}5{\times}2mm^3$) were prepared from human periodontally diseased extracted teeth and grouped into 4 groups: 1) control (root planing only), 2) root planing and irradiated with laser at 30mJ, 3) root planing and irradiated with laser at 60mJ, and 4) root planing and irradiated with laser at 100mJ. The root slabs were embedded in resin block before laser treatment. Er:YAG laser was irradiated under water irrigation with the tip held perpendicular to the root surface in contact mode. After Er:YAG laser irradiation or planing on the root surface, morphological changes have been observed under SEM, and the micro-hardness and Ca/P ratio were compared. 1. In the Control group, the root surface showed the directional change caused by root planing instrumentation, and the presence of smear layer, and no exposure of dentinal tubule was observed. Laser irradiated group showed surface changes with rough dentin surface of niche and depression and dentinal tubule exposure by the elimination of smear layer. 2. The micro-hardness of root surface in the laser irradiated group was higher than the control group. The higher energy output was applied, the higher micro-hardness on root surface was resulted. 3. The higher energy output was applied, the higher Ca/P ratio was observed. The higher Ca/P ratio in 60mJ group and 100mJ group was statistically significantly compared to the control group and the 30mJ group. These results suggest that Er:YAG laser irradiation on the periodontally diseased root surface could remove smear layer and increase the micro-hardness on root surface and Ca/P ratio which contribute to enhance the acid resistance of periodontally treated root surface.

• Restorative Dentistry and Endodontics
• /
• 제39권3호
• /
• pp.180-186
• /
• 2014

Objectives: The purpose of this in vitro study was to evaluate the microleakage and penetration of fissure sealant in permanent molar teeth with fluorosis after pretreatment of the occlusal surface. Materials and Methods: A total of 120 third molars with mild dental fluorosis were randomly divided into 6 groups (n = 20). The tooth surfaces were sealed with an unfilled resin fissure sealant (FS) material. The experimental groups included: 1) phosphoric acid etching (AE) + FS (control); 2) AE + One-Step Plus (OS, Bisco) + FS; 3) bur + AE + FS; 4) bur + AE + OS + FS; 5) Er:YAG laser + AE + FS; and 6) Er:YAG laser + AE + OS + FS. After thermocycling, the teeth were immersed in 0.5% fuchsin and sectioned. Proportions of mircoleakage (PM) and unfilled area (PUA) were measured by digital microscope. Results: Overall, there were significant differences among all groups in the PM (p = 0.00). Group 3 showed the greatest PM, and was significantly different from groups 2 to 6 (p < 0.05). Group 6 showed the lowest PM. Pretreatment with Er:YAG with or without adhesive led to less PM than bur pretreatment. There were no significant differences among groups in PUA. Conclusions: Conventional acid etching provided a similar degree of occlusal seal in teeth with fluorosis compared to those pretreated with a bur or Er:YAG laser. Pretreatment of pits and fissures with Er:YAG in teeth with fluorosis may be an alternative method before fissure sealant application.

• Restorative Dentistry and Endodontics
• /
• 제39권4호
• /
• pp.296-302
• /
• 2014

Objectives: It is difficult to achieve adhesion between resin cement and zirconia ceramics using routine surface preparation methods. The aim of this study was to evaluate the effects of $CO_2$ and Er:YAG laser treatment on the bond strength of resin cement to zirconia ceramics. Materials and Methods: In this in-vitro study 45 zirconia disks (6 mm in diameter and 2 mm in thickness) were assigned to 3 groups (n = 15). In control group (CNT) no laser treatment was used. In groups COL and EYL, $CO_2$ and Er:YAG lasers were used for pretreatment of zirconia surface, respectively. Composite resin disks were cemented on zirconia disk using dual-curing resin cement. Shear bond strength tests were performed at a crosshead speed of 0.5 mm/min after 24 hr distilled water storage. Data were analyzed by one-way ANOVA and post hoc Tukey's HSD tests. Results: The means and standard deviations of shear bond strength values in the EYL, COL and CNT groups were $8.65{\pm}1.75$, $12.12{\pm}3.02$, and $5.97{\pm}1.14MPa$, respectively. Data showed that application of $CO_2$ and Er:YAG lasers resulted in a significant higher shear bond strength of resin cement to zirconia ceramics (p < 0.0001). The highest bond strength was recorded in the COL group (p < 0.0001). In the CNT group all the failures were adhesive. However, in the laser groups, 80% of the failures were of the adhesive type. Conclusions: Pretreatment of zirconia ceramic via $CO_2$ and Er:YAG laser improves the bond strength of resin cement to zirconia ceramic, with higher bond strength values in the $CO_2$ laser treated samples.

• Journal of Oral Medicine and Pain
• /
• 제31권3호
• /
• pp.211-221
• /
• 2006

목적 전통적 고속 회전식 절삭기구 또는 Er:YAG 레이저로 삭제된 상아질에, 두가지 다른 접착 시스템을 적용한 후, 축조한 컴포지트 레진의 미세인장결합강도를 비교하고, 다양한 Er:YAG 레이저 에너지가 미세인장결합강도에 미치는 영향을 평가한다. 재료 및 방법 40개의 제3대구치를 사용하여, 평평한 상아질면을 만든 후 8개의 군으로 나누어, 4가지 절삭방법 (고속 회전식 절삭기구, 2 W, 3 W, 4 W 출력의 Er:YAG 레이저) 중 한 가지로 삭제하고, 2가지 접착 시스템 (Scotchbond Multipurpose Plus, Clearfil SE bond) 중 한 가지로 처리하여 컴포지트 레진을 축조하였다. 24시간의 저장 후, 각 시편을 결합면에 수직으로 자르고, 미세인장결합강도를 측정하였다. 각 군의 미세인장결합강도는 평균$\pm$표준 편차로 표현하였고, 통계분석을 위해 two-way ANOVA, one-way ANOVA, student-Newman-Keuls' multiple comparison test, 그리고 t-test가 사용되었다. 결과 및 결론 1. 접착시스템과 관계없이, 절삭방법에 따른 미세인장결합강도의 유의한 차이가 있었고, 높은 순서대로 나열하면 다음과 같다: 3 W, 2 W, Bur, 4 W (p<0.001). 2. 절삭방법과 관계없이, Scotchbond Multipurpose Plus로 처리한 군이 Clearfil SE bond로 처리한 군보다 유의하게 높은 미세인장결합강도를 나타냈다 (p<0.001). 3. Scotchbond Multipurpose Plus로 처리한 군 중에서, 3 W 레이저 절삭군이 가장 높은 미세인장결합강도를 나타냈고, 다음이 Bur, 2 W, 4 W 절삭군 순이었다 (p<0.001). 4. Clearfil SE bond로 처리한 군 중에서 3 W 레이저 절삭군이 가장 높은 미세인장결합강도를 나타냈고, 다음이 2 W, 4 W, Bur 절삭군 순이었다 (p<0.001). 5. 두 가지 접착 시스템 모두에서, 레이저로 절삭한 군의 미세인장결합강도의 차이가 있었고, 높은 순서대로 나열하면 3 W, 2 W, 4 W 순이었다 (p<0.001). :상아질에 접착된 컴포지트 레진의 미세인장결합강도는 절삭방법과 접착시스템의 상호작용에 의해 유의한 영향을 받았다. 임상에서 레진 수복시, 2 W-3 W 범위내로 Er:YAG laser를 사용한다면 전통적 핸드피스 못지않게 수복물의 우수한 결합강도를 얻을 수 있다. 특히 시술시간의 단축, 과도한 산부식에 따른 부작용의 예방을 위해 Clearfil SE bond를 포함한 self etching system을 사용하고자 한다면 bur보다 Er:YAG laser를 이용한 삭제방법이 더 유용한 결합력을 제공할 것이다.

• 한국결정성장학회지
• /
• 제26권4호
• /
• pp.131-134
• /
• 2016

Czochralski 법으로 성장한 RE : YAG ($RE=Nd^{3+}\;,Er^{3+}\;,Yb^{3+}$) 단결정의 표면 결함을 측정하는 chemical polishing 및 etching 조건에 대하여 조사하였다. 최적의 chemical polishing 조건은 시편을 수직 방향으로 고정하고 85 % $H_3PO_4$ 용액에서 $330^{\circ}C$, 30분 동안 진행한 것이었다. 또한 최적의 chemical etching 조건은 85 % $H_3PO_4$ 용액에서 $260^{\circ}C$, 1시간 동안 진행한 것이었고, (111) 면에 $70~80{\mu}m$ 크기의 삼각형 etch pit들이 관찰되었다. 결함 밀도 분석 결과, Nd(1 %) : YAG는 $1.9{\times}10^3$개/$cm^2$, Er(7.3 %) : YAG는 $4.3{\times}10^2$개/$cm^2$, Yb(15 %) : YAG는 $5.1{\times}10^2$개/$cm^2$로 측정되었다.

• 대한치과의사협회지
• /
• 제53권12호
• /
• pp.917-925
• /
• 2015

LASER application has many advantages in the field of dentistry, however, it is not easy to apply dental LASER in general practice. Various LASER systems are in the market and it is little bit confused which LASER systems are useful. Most of all, it is important to select the appropriate LASER system to their own usage. In the present article, I introduce several LASER system such as $CO_2$, Diode, Nd:YAG, Er:YG, Er,Cr:YSGG, and its application according to specific disease criteria.

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

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

• Restorative Dentistry and Endodontics
• /
• 제36권5호
• /
• pp.409-418
• /
• 2011

연구목적: 이 연구는 상아질 표면에 Er:YAG 레이저를 조사하지 않는 군, 레이저를 조사한 군, 레이저를 조사한 후 부가적인 산처리를 한 군으로 분류하여 2단계 단일병 전부식 접착시스템과 자가부식 프라이머 접착시스템을 이용하여 복합레진을 접착하였을 때 이러한 표면처리가 복합레진의 미세전단 결합강도와 결합계면에 미치는 영향을 비교하기 위하여 시행하였다. 연구 재료 및 방법: 32개의 발거된 대구치의 교합면측 상아질을 이용하였고, 상아질의 표면처리는 1군과 4군에서 각각 인산과 자가부식 프라이머로 하였으며, 2군과 5군은 Er:YAG 레이저로 에칭처리하였고, 3군과 6군은 레이저로 에칭한 후 다시 각각 인산과 자가부식 프라이머로 하였다. 1군, 2군, 3군은 Single Bond 2와 Z 250 (3M ESPE)을 이용하였고, 4군, 5군, 6군은 Clearfil SE Bond와 Clearfil AP-Z (Kuraray)을 이용하여 상아질 면에 Tygon tube를 접착하였다. 각 군의 미세전단 결합강도를 측정한 후 통계 처리하였고, 또한 6개의 시편에서 복합레진과 상아질 계면을 주사전자현미경하에서 관찰하였다. 결과: Single Bond 2를 사용한 군에서 2군의 결합강도는 1군과 3군보다 통계학적으로 낮게 나타났으며, Clearfil SE Bond를 사용한 군에서 4군, 5군, 6군의 결합강도는 각각 통계학적으로 유의한 차이를 나타내었다(p < 0.05). 2군과 5군은 아주 짧고 가는 레진테그가 관찰되었고, 3군과 6군은 길고 가는 레진테그와 레진테그의 측지가 관찰되었다. 결론: 레이저로 에칭 처리한 상아질에 대한 부가적인 산 처리나 자가부식 프라이머의 처리는 상아질의 접착력을 향상시켰다.