Nammour Samir, El Mobadder Marwan, Brugnera Aldo, Arany Praveen, El Feghali Mireille, Nahas Paul, Vanheusden Alain
Department of Dental Science, Faculty of Medicine, University of Liege, 4000 Liege, Belgium.
Laser Laboratory, Oral Surgery Department, Wroclaw Medical University, 50-425 Wroclaw, Poland.
Dent J (Basel). 2025 Aug 19;13(8):376. doi: 10.3390/dj13080376.
: This study aimed to evaluate the efficacy of a 445 nm diode laser in enhancing enamel resistance to acid-induced demineralization and to investigate the associated compositional and structural modifications using scanning electron microscopy (SEM), electron spectroscopy for chemical analysis (ESCA), and X-ray diffraction (XRD) crystallographic analysis. : A total of 126 extracted human teeth were used. A total of 135 ( = 135) enamel discs (4 × 4 mm) from 90 teeth were assigned to either a laser-irradiated group or an untreated control group for SEM, ESCA, and XRD analyses. Additionally, 24 mono-rooted teeth were used to measure pulp temperature changes during laser application. Laser irradiation was performed using a 445 nm diode laser with a pulse width of 200 ms, a repetition rate of 1 Hz, power of 1.25 W, an energy density of 800 J/cm, a power density of 3980 W/cm, and a 200 µm activated fiber. Following acid etching, SEM was conducted to assess microstructural and ionic alterations. The ESCA was used to evaluate the Ca/P ratio, and XRD analyses were performed on enamel powders to determine changes in phase composition and crystal lattice parameters. : The laser protocol demonstrated thermal safety, with minimal pulp chamber temperature elevation (0.05667 ± 0.04131 °C). SEM showed that laser-treated enamel had a smoother surface morphology and reduced acid-induced erosion compared with controls. Results of the ESCA revealed no significant difference in the Ca/P ratio between groups. XRD confirmed the presence of hydroxyapatite structure in laser-treated enamel and detected an additional diffraction peak corresponding to a pyrophosphate phase, potentially enhancing acid resistance. Results of the spectral analysis showed the absence of α-TCP and β-TCP phases and a reduction in the carbonate content in the laser group. Furthermore, a significant decrease in the a-axis lattice parameter suggested lattice compaction in laser-treated enamel. : Irradiation with a 445 nm diode laser effectively enhances enamel resistance to acid demineralization. This improvement may be attributed to chemical modifications, particularly pyrophosphate phase formation, and structural changes including prism-less enamel formation, surface fusion, and decreased permeability. These findings provide novel insights into the mechanisms of laser-induced enhancement of acid resistance in enamel.
本研究旨在评估445纳米二极管激光增强牙釉质抗酸脱矿能力的效果，并使用扫描电子显微镜（SEM）、化学分析电子能谱（ESCA）和X射线衍射（XRD）晶体分析来研究相关的成分和结构变化。总共使用了126颗拔除的人类牙齿。从90颗牙齿上制备了135个（n = 135）牙釉质圆盘（4×4毫米），分为激光照射组和未处理的对照组，用于SEM、ESCA和XRD分析。此外，使用24颗单根牙测量激光照射过程中的牙髓温度变化。使用脉冲宽度为200毫秒、重复频率为1赫兹、功率为1.25瓦、能量密度为800焦/平方厘米、功率密度为3980瓦/平方厘米的445纳米二极管激光和200微米的激活光纤进行激光照射。酸蚀后，进行SEM以评估微观结构和离子变化。ESCA用于评估钙磷比，对牙釉质粉末进行XRD分析以确定相组成和晶格参数变化。激光方案显示出热安全性，牙髓腔温度升高最小（0.05667±0.04131℃）。SEM显示，与对照组相比，激光处理的牙釉质表面形态更光滑，酸蚀减少。ESCA结果显示两组之间钙磷比无显著差异。XRD证实激光处理的牙釉质中存在羟基磷灰石结构，并检测到一个对应于焦磷酸相的额外衍射峰，可能增强了抗酸性。光谱分析结果显示激光组中不存在α-磷酸三钙和β-磷酸三钙相，碳酸盐含量降低。此外，a轴晶格参数的显著降低表明激光处理的牙釉质中晶格致密化。445纳米二极管激光照射有效地增强了牙釉质的抗酸脱矿能力。这种改善可能归因于化学修饰，特别是焦磷酸相的形成，以及结构变化，包括无棱柱牙釉质的形成、表面融合和渗透性降低。这些发现为激光诱导牙釉质抗酸性增强的机制提供了新的见解。
