El Mansy Maryam M, Gheith Mostafa, El Yazeed Abo M, Farag Dina B E
Orthodontic and Pedodontic Department, National Research Centre, Cairo, Egypt.
National Institute of Laser Enhanced Sciences, Cairo University, Cairo, Egypt.
Open Access Maced J Med Sci. 2019 May 30;7(11):1828-1833. doi: 10.3889/oamjms.2019.359. eCollection 2019 Jun 15.
Enamel demineralisation is an initial step of the serious dental problem including dental caries, white spot lesions and dental erosion.
Compare the effect of Er, Cr: YSGG (λ = 2780 nm) and nanosecond Nd: YAG (λ = 1064 nm) laser on enamel acid resistance.
Thirty non-carious human premolars, extracted for orthodontic reasons, were used. The experimental groups (n = 10 each group) were: Group I, untreated (control); Group II, Er, Cr: YSGG laser irradiation (0.75 W, 20 Hz, 140 μs, 10 s); Group III, nanosecond pulsed Nd: YAG laser irradiation (0.8 W, 10 Hz, 7 ns, 10 s). Scanning electron microscope and Energy Dispersive X-ray Spectroscopy (EDX) were used to assess acquired enamel resistance to PH cycling.
After subjecting the three experimental groups to PH cycling, scanning electron microscopic examination revealed irregular porous dissoluted enamel surface in group I. However, groups II and III demonstrated partially dissoluted enamel surface. EDX analysis demonstrated the lowest mean percentage decrease in calcium and phosphorus content in group II followed by group III, then the highest mean percentage decrease was observed in untreated group I. One-way ANOVA revealed significant differences (p < 0.0001) between the tested groups.
Both Er, Cr: YSSG and nanosecond Nd: YAG laser irradiation were able to improve the acid resistance of enamel. However, enamel surface treated with Er, Cr: YSSG laser showed the lowest mean percentage decrease of calcium and phosphorus (highest acid resistance).
牙釉质脱矿是包括龋齿、白斑病变和牙侵蚀在内的严重牙齿问题的初始阶段。
比较铒铬：钇钪镓石榴石（λ = 2780纳米）激光和纳秒钕：钇铝石榴石（λ = 1064纳米）激光对牙釉质耐酸性的影响。
使用因正畸原因拔除的30颗非龋人类前磨牙。实验组（每组n = 10）为：第一组，未处理（对照组）；第二组，铒铬：钇钪镓石榴石激光照射（0.75瓦，20赫兹，140微秒，10秒）；第三组，纳秒脉冲钕：钇铝石榴石激光照射（0.8瓦，10赫兹，7纳秒，10秒）。使用扫描电子显微镜和能量色散X射线光谱仪（EDX）评估获得的牙釉质对pH循环的耐受性。
对三组实验组进行pH循环处理后，扫描电子显微镜检查显示第一组牙釉质表面有不规则的多孔溶解现象。然而，第二组和第三组显示牙釉质表面部分溶解。EDX分析表明，第二组钙和磷含量的平均百分比下降最低，其次是第三组，未处理的第一组平均百分比下降最高。单因素方差分析显示测试组之间存在显著差异（p < 0.0001）。
铒铬：钇钪镓石榴石激光和纳秒钕：钇铝石榴石激光照射均能提高牙釉质的耐酸性。然而，经铒铬：钇钪镓石榴石激光处理的牙釉质表面钙和磷的平均百分比下降最低（耐酸性最高）。
