Laboratory processing methods and bonding to glass ceramics: Systematic review

This systematic review provides a summary of the available evidence from in vitro studies that evaluate the effect of different glass ceramic processing methods on the bond strength to resin-based luting agents. The review protocol was pre-registered (doi 10.17605/OSF.IO/B9R4J), and a search was conducted across nine databases to identify articles and registers (April 2023) that met pre-defined eligibility criteria. The PICO question included glass ceramics (population), CAD-CAM ceramic processing method (intervention), layering or heat-pressing processing methods (comparison), and bond strength to resin-based materials and failure modes (outcomes). Out of the 2395 unique records screened, five studies were included in the analysis. Methodological quality and risk of bias were assessed using the RoBDEMAT tool, and a narrative synthesis of the evidence was conducted. The studies investigated the use of lithium disilicate ceramics or feldspathic ceramics and employed a variety of adhesive materials, surface treatments, bonding procedures, tests, and aging methods. The assessment of risk of bias and methodological quality raised concerns, particularly the reporting of sample size rationale, randomization of samples, and blinding of operators. The analysis of failure modes did not provide strong evidence regarding the impact of ceramic processing methods on the bonding ability of resin-based materials. Overall, the findings suggest that the bond strength between resin-based materials and feldspathic and lithium disilicate ceramics processed by the CAD-CAM method is generally higher compared to heat-pressing or layering processing methods.