In vitro study on nanosecond-pulsed Q-switched Er:YAG laser-induced selective removal for caries dentin

被引：0
作者：
Kondo S. [1 ]
Hazama H. [1 ]
Tanaka K. [2 ]
Kasakawa A. [2 ]
Sekine S. [3 ]
Akiyama S. [2 ]
Awazu K. [1 ,4 ,5 ]
机构：
[1] Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka
[2] Division of Special Care Dentistry, Osaka University Dental Hospital, 1-8 Yamadaoka, Suita, Osaka
[3] Preventive Dentistry, Osaka University Dental Hospital, 1-8 Yamadaoka, Suita, Osaka
[4] Global Center for Advanced Medical Engineering and Informatics, Osaka University, 2-2 Yamadaoka, Suita, Osaka
[5] Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka
来源：
Lasers in Dental Science | 2020年 / 4卷 / 4期
关键词：
Bovine dentin; In vitro; Nanosecond-pulsed Q-switched Er:YAG laser; Selective removal; Thermal effect; Without water spray;
D O I：
10.1007/s41547-020-00106-7
中图分类号：
学科分类号：
摘要：
Purpose: Since 2000, Fédération Dentaire Internationale has advocated for “minimal intervention” dental treatments. The dental field has demanded less-invasive caries treatment methods. However, recent caries treatments using a microsecond-pulsed free-running Er:YAG laser with a pulse duration of 200–300 μs have issues with non-selectivity for caries due to the thermal effect caused by the laser. To improve the selectivity by reducing the thermal effect, the ablation characteristics of a nanosecond-pulsed Er:YAG laser are investigated. Methods: A Q-switched Er:YAG laser with a rotating mirror Q-switching system attached to a flash lamp-pumped Er:YAG laser and a free-running Er:YAG laser were used. The pulse duration of the Q-switched Er:YAG laser was 80–130 ns, while that of the free-running Er:YAG laser was around 200 μs. The pulse repetition rate of the free-running Er:YAG laser was constant at 10 Hz, but that of the Q-switched Er:YAG laser fluctuated between 10 and 23 Hz. The fluence was 6, 10, or 14 J/cm2. The samples were bovine sound dentin slices and caries models. Caries models were prepared by immersing sound dentin slice samples into a 0.1-M lactic acid solution for 24 h at 37 °C. The samples were irradiated with the two lasers horizontally without water spray for 1, 2, or 4 s. Results: Laser irradiation experiments indicate that the selectivity towards caries occurs at the fluence of 6 J/cm2 without water spray. The ablation depth of a demineralized dentin slice by the Q-switched Er:YAG laser is about three times that by the free-running Er:YAG laser at the fluence of 10 J/cm2. In addition, the Q-switched Er:YAG laser suppresses the thermal effect reducing the range of the thermal melting area. Conclusions: Caries dentin may be selectively removed without water spray using the Q-switched Er:YAG laser with suppressing dental pulp necrosis because the temperature increase is below 5 °C. The ablation depths by the Q-switched Er:YAG are about three times larger than those using the free-running Er:YAG laser. © 2020, Springer Nature Switzerland AG.
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页码：195 / 202
页数：7
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