Center of Dentistry, Department of Prosthetic Dentistry, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
Center for Dental and Oral Medicine, Department of Orthodontics, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany.
Lasers Med Sci. 2022 Mar;37(2):1017-1030. doi: 10.1007/s10103-021-03348-4. Epub 2021 Jul 11.
Inadvertent Er:YAG laser irradiation occurs in dentistry and may harm restorative materials in teeth. The aim of this in vitro study was to quantify Er:YAG laser-induced damage to a nanohybrid composite in simulated clinical scenarios for inadvertent direct and indirect (reflection) laser irradiation. The simulation was performed by varying the output energy (OE;direct˃indirect) reaching the specimen and the operating distance (OD;direct˂indirect). Composite specimens were irradiated by an Er:YAG laser. The ablation threshold was determined and clinically relevant parameters were applied (n = 6 for each OE/OD combination) for direct (OE: 570 mJ/OD: 10 mm, OE: 190 mJ/OD: 10 mm) and indirect irradiation (OE: 466 mJ/OD: 15 mm, OE: 57 mJ/OD: 15 mm, OE: 155 mJ/OD: 15 mm, OE: 19 mJ/OD: 15 mm). The extent of damage in the form of craters was evaluated using a laser scanning microscope (LSM) and a conventional light microscope (LM). The ablation threshold was determined to be 2.6 J/cm. The crater diameter showed the highest value (LM: 1075 ± 18 µm/LSM: 1082 ± 17 µm) for indirect irradiation (reflectant:dental mirror) (OE: 466 mJ/OD: 15 mm). The crater depth showed the highest and comparable value for direct (OE: 570 mJ/OD: 10 mm; LSM: 89 ± 2 µm) and indirect irradiation (OE: 466 mJ/OD: 15 mm; LSM: 90 ± 4 µm). For each OD, the crater diameter, depth, and volume increased with higher laser fluence. However, the OD-and thus the laser spot diameter-also had an enlarging effect. Thus, indirect irradiation (reflectant:dental mirror) with only 47% of the laser fluence of direct irradiation led to a larger diameter and a comparable depth. The three-dimensional extent of the crater was large enough to cause roughening, which may lead to plaque accumulation and encourage caries, gingivitis, and periodontitis under clinical conditions. Clinicians should be aware that reflected irradiation can still create such craters.
钇铝石榴石激光照射，并且可能会损害牙齿中的修复材料。本体外研究的目的是量化在模拟临床情况下，无意的直接和间接（反射）激光照射对纳米复合树脂的激光损伤。通过改变到达样本的输出能量（OE；直接＞间接）和操作距离（OD；直接＜间接）来进行模拟。复合样本通过铒：钇铝石榴石激光照射。确定了消融阈值，并应用了临床相关参数（每个 OE/OD 组合各 6 个样本）进行直接（OE：570 mJ/OD：10 mm，OE：190 mJ/OD：10 mm）和间接照射（OE：466 mJ/OD：15 mm，OE：57 mJ/OD：15 mm，OE：155 mJ/OD：15 mm，OE：19 mJ/OD：15 mm）。使用激光扫描显微镜（LSM）和常规显微镜（LM）评估以凹坑形式出现的损伤程度。确定消融阈值为 2.6 J/cm。凹坑直径显示间接照射（反射：牙科镜）的最高值（LM：1075±18 µm/LSM：1082±17 µm）（OE：466 mJ/OD：15 mm）。凹坑深度对于直接（OE：570 mJ/OD：10 mm；LSM：89±2 µm）和间接（OE：466 mJ/OD：15 mm；LSM：90±4 µm）照射，具有最高且可比的值。对于每个 OD，随着激光强度的增加，凹坑直径、深度和体积均增加。但是，OD 也具有放大效果。因此，间接照射（反射：牙科镜）的激光强度仅为直接照射的 47%，但却导致了更大的直径和可比的深度。凹坑的三维范围足够大，足以导致表面粗糙，这可能导致在临床条件下菌斑的积累，并鼓励龋齿、牙龈炎和牙周炎的发生。临床医生应注意到，反射照射仍可能会造成此类凹坑。
