Effect of low-power laser irradiation on the shear bond strength and thermal changes across different zirconia thicknesses using different irradiation times.

PURPOSE: To investigate the effect of irradiation time and zirconia thickness using low power Er,Cr:YSGG laser irradiation (for debonding purposes) on the thermal changes and shear bond strength of resin-bonded 3% mol yttrium oxide stabilized tetragonal zirconia polycrystal (3Y-TZP) specimens. MATERIALS AND METHODS: 3Y-TZP slices of 0.5, 2, and 3 mm thick were used. The temperature during laser irradiation using single spot irradiation at different times (30, 60, 90, and 120 s) and line scanning irradiation from one spot tanother at three different distances (2-, 4-, and 6- mm) were recorded. Single spot and line scanning irradiation data were analyzed using three-way ANOVA (α: 0.05) and generalized linear mixed model, respectively. Non-irradiated (control) and irradiated resin-bonded 3Y-TZP specimens were shear tested, and the data were analyzed using two-way ANOVA (α: 0.05). RESULTS: Under single spot irradiation, the laser-induced temperature was higher through thin 3Y-TZP at any time compared to thick 3Y-TZP. For the line scanning method, short distances (2 and 4 mm) resulted in a significant increase in temperature in 0.5 mm thick specimens. Laser irradiation significantly decreased the shear bond strength of the 0.5 mm group compared to the non-irradiated group. After irradiation, the bond strength of the 2- and 3-mm thick 3Y-TZP was similar to the non-irradiated group. CONCLUSION: The temperature and bond strength of low-power laser irradiated 3Y-TZP specimens was affected by the specimen thickness but not by the irradiation time tested. Low-power laser irradiation is an effective debonding method for thin Y-TZP restorations.

Bonding and Debonding of Zirconia Using Laser Approaches.

PURPOSE: To describe the current findings regarding the use of lasers to enhance the bonding properties of zirconia and to enable its debonding. MATERIALS AND METHODS: The PudMed database was searched for literature up to July 2021. The keywords used for zirconia surface treatment were: laser irradiation; zirconia; and bond strength. For ceramic laser debonding, the keywords were: laser irradiation; ceramic; and debonding. RESULTS: A total of 36 studies were included for zirconia surface treatment, and 12 for ceramic laser debonding. Nd:YAG, CO2, Er:YAG, Er,Cr:YSGG, and ultrashort lasers were used for surface treatment, whereas only Er:YAG and Er,Cr:YSGG lasers were applied to debond zirconia structures. CONCLUSION: The use of laser irradiation to improve the bonding properties of zirconia depends on the type of laser and the parameters used. Among the laser types included in this review, ultrashort lasers have shown the most promising results; however, more studies are needed to prove their superiority over the other lasers for enhancing zirconia bond strength. In terms of debonding, irradiation with different lasers was effective regardless of the ceramic type; however, well-established protocols (ie, laser irradiation time and motion, laser settings) are still needed for different thicknesses and material ceramic types.

A Digital Method to Fabricate the Ocular Portion of An Orbital Prosthesis with A Smartphone Camera, Color Calibration and Digital Printing.

Conventional techniques described in the literature for the manufacture of ocular prostheses are time-consuming since they involve manual work. The use of technologies could improve this laborious process, providing better esthetic outcomes. This technique describes how to manufacture the ocular portion of an orbital prosthesis using a smartphone camera, color calibration with a tooth shade guide, and digital printing. This method allows clinicians to fabricate customized ocular prosthesis by using a photograph of the patient's eye, thus eliminating the need for hand-painting and manual work, and reducing fabrication time.