Effect of laser irradiation on the adhesion of resin-based materials to zirconia: a systematic review and meta-analysis

This systematic review and meta-analysis were made to evaluate the bond strength behavior and failure mode of zirconia surfaces treated by laser irradiation and to highlight the main characteristics and parameters of each laser system. The PubMed, the Scopus, and the Web of Science databases were searched for articles without limit on year of publication, in accordance with the PRISMA guidelines. Forty-three <i>in vitro</i> studies were included and meta-analyses were performed to compare the bond strength values found after the use of lasers, and to quantify the percentage of failures. When compared to untreated groups, the bond strength values found for the lasers ranged from 1.4 to 30.16 MPa for CO₂; 1.18 to 40.33 MPa for Nd:YAG; 0 to 22.72 MPa for Er:YAG; and 0.5 to 34.92 MPa for Er,Cr:YSGG. Statistical analysis indicated high heterogeneity in-between the comparisons of different lasers (<i>p</i> ˂ 0.05). When compared to other treatments, the results of the meta-analysis were favorable for tribochemical silica coating (TSC) and airborne-particle abrasion (APA) (<i>p</i> ˂ 0.05), except for the CO₂ laser. Adhesive failures were predominant (68.28% for CO_2; 65.23% for Nd:YAG; 76% for Er:YAG and 71.91% for Er,Cr:YSGG laser), followed by mixed and cohesive failures. Based on the results of this study, the conditioning of zirconia surfaces through laser irradiation increases the bond strength values when compared to untreated surfaces, regardless of the type of laser used. However, except for CO₂ laser, TSC and APA still show superior bond strength results.

本系统综述与荟萃分析旨在评估激光辐照处理后氧化锆表面的粘结强度特性与失效模式，并阐明各类激光系统的主要特征与参数。本研究遵循PRISMA声明（PRISMA guidelines）的规范，未设置发表年份限制，对PubMed、Scopus及Web of Science数据库进行了文献检索。最终纳入43项体外（in vitro）研究，并开展荟萃分析，以对比不同激光处理后的粘结强度数值，同时量化各类失效的占比。与未处理组相比，各类激光处理后的粘结强度范围分别为：CO₂激光1.4~30.16 MPa、Nd:YAG激光1.18~40.33 MPa、Er:YAG激光0~22.72 MPa、Er,Cr:YSGG激光0.5~34.92 MPa。统计学分析显示，不同激光组间的比较存在高度异质性（p < 0.05）。与其他表面处理方式相比，荟萃分析结果表明，除CO₂激光外，机械化学硅涂层（tribochemical silica coating, TSC）与空气喷砂颗粒处理（airborne-particle abrasion, APA）的粘结强度效果更优（p < 0.05）。失效模式以粘结失效为主，其中CO₂激光组占68.28%、Nd:YAG激光组占65.23%、Er:YAG激光组占76%、Er,Cr:YSGG激光组占71.91%，其次为混合失效与内聚失效。基于本研究结果，无论采用何种类型的激光，激光辐照处理氧化锆表面均可较未处理组提升粘结强度；但除CO₂激光外，机械化学硅涂层与空气喷砂颗粒处理仍能获得更优异的粘结强度效果。