Objectives

The aim of this study was to evaluate the effect of laser surface structuring on the bond strength of feldspar-based porcelain to zirconia, as compared to conventional sandblasting treatment.

Materials and methods

Thirty cylindrical zirconia substrates, previously sintered, were divided in three groups according to the type of surface conditioning: 1) sandblasting with 50 µm Al₂O₃; 2) laser structuring (Ø25 µm holes); and 3) laser structuring (Ø50 µm holes). Porcelain was injected onto the zirconia substrates. X-ray diffractometry (XRD) was used to evaluate the influence of the laser treatment on zirconia crystallographic phases. Shear bond strength test was performed. Micrographs using SEM were used to evaluate the zirconia surface after each surface treatment and to evaluate the fracture surface after the shear test.

Results

The laser-structured groups presented the highest shear bond strength (65 ± 16 MPa and 65 ± 11 MPa, for the 25 µm and 50 µm holes, respectively). The sandblasting samples presented shear bond strength of 37 ± 16 MPa. XRD analysis showed that there was no phase transformation on the thermally affected surface due to laser action. Microcracks were created at some holes due to the high temperature gradient generated by laser.

Significance

Laser structuring significantly increased (up to 75%) the shear bond strength of zirconia to veneering porcelain as compared to conventional sandblasting treatment. Therefore, laser structuring arises as a surface conditioning method for producing stronger and long lasting zirconia-porcelain interfaces.

中文翻译：

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Nd：YAG激光表面结构增强氧化锆-瓷界面的结合强度

目标

这项研究的目的是评估与传统的喷砂处理相比，激光表面结构化对长石基瓷与氧化锆结合强度的影响。

材料和方法

根据表面处理的类型，将30块事先烧结的圆柱状氧化锆衬底分为三类：1）用50 µm Al ₂ O ₃喷砂；2）激光结构化（Ø25µm孔）；3）激光结构化（Ø50µm孔）。瓷被注入到氧化锆衬底上。X射线衍射仪（XRD）用于评估激光处理对氧化锆晶体相的影响。进行剪切粘结强度测试。在每次表面处理后，使用SEM显微照片评估氧化锆表面，并在剪切试验后评估断裂表面。

结果

激光结构组表现出最高的剪切粘结强度（对于25 µm和50 µm的孔分别为65±16 MPa和65±11 MPa）。喷砂样品的剪切粘结强度为37±16 MPa。XRD分析表明，由于激光作用，在热影响表面上没有相变。由于激光产生的高温梯度，在某些孔处产生了微裂纹。

意义

与常规喷砂处理相比，激光结构化可显着提高（高达75％）氧化锆与饰面瓷的剪切粘结强度。因此，激光结构化作为用于产生更强和持久的氧化锆-瓷界面的表面调节方法而出现。