A new adhesive technology for all-ceramics.

Current bonding techniques for ceramics involve etching and silanization, but these methods may not consistently provide stable adhesion to all ceramic types. While silane application is widely used, its effectiveness depends on surface preparation and material composition. Some ceramics, like zirconia, resist traditional bonding approaches due to their inert surfaces. This gap motivated researchers to explore alternative surface treatments that could improve adhesion without compromising material integrity. No prior work had resolved how to consistently bond zirconia-based ceramics to composites. Existing studies have shown that surface roughening and chemical activation can influence bond strength, but results vary across ceramic types. This uncertainty drove the development of a new method using flame treatment to activate ceramic surfaces. The goal was to find a universal treatment that could work across multiple ceramic compositions.

The aim of this study was to evaluate a novel surface treatment method using flame exposure to enhance the bond strength between luting composites and various ceramic materials. The researchers focused on four specific ceramics: Empress II, InCeram-Alumina, InCeram-Zirconia, and Frialit (ZrO2). The motivation came from the need to find a reliable and consistent bonding solution for all-ceramic restorations. Traditional methods like etching and silanization may not work equally well on all ceramic types. The study sought to determine if flame treatment could provide a more effective alternative. By varying the duration of flame exposure, the team aimed to identify the optimal treatment time for each material. They also wanted to confirm whether this treatment could activate surfaces in a way that promotes stable bonding. The investigation included both mechanical testing and spectroscopic analysis to assess surface changes.

The study followed the ISO 10477 Amendment 1 protocol for specimen preparation and testing. Ceramic surfaces were ground with 400 grit paper, then polished with 800 grit and air-dried. Three groups of 10 specimens each were created for each ceramic type. Each group received flame treatment with the PyrosilPen for 2.5, 5, or 10 seconds per square centimeter. After treatment, a methacryl silane was applied, followed by a luting composite. Specimens were thermocycled 5,000 times between 5°C and 55°C to simulate aging. Shear bond strength was measured as the primary outcome. Scanning electron microscopy (SEM) and Fourier-transform infrared spectrophotometry (FT-IR) were used to analyze surface morphology and chemical changes. A control group used Empress II that was etched and silanized. The study compared bond strength values across treatment times and ceramic types.

The optimal flame treatment time was found to be 5 seconds per square centimeter across all tested ceramics. At this time, bond strength values were 23 MPa for Empress II, 23 MPa for InCeram-Alumina, 13 MPa for InCeram-Zirconia, and 16 MPa for Frialit. The control group achieved 27 MPa with etching and silanization. These results suggest that flame treatment can produce bond strengths comparable to traditional methods for some ceramics. However, zirconia-based materials showed lower values than others. FT-IR analysis detected silicon on all flamed surfaces, indicating successful activation. SEM confirmed surface changes consistent with treatment effects. Thermocycling did not significantly reduce bond strength, suggesting good durability. These findings indicate that flame treatment is a viable alternative for ceramic bonding.

The PyrosilPen technology provides an effective and easy-to-apply method for surface treatment of ceramics. The authors propose that this approach can be used for silicate, aluminum oxide, and zirconium oxide ceramics to improve bonding with luting composites. The study found that 5 seconds per square centimeter is the optimal treatment time for most materials. The results suggest that flame treatment activates ceramic surfaces in a way that promotes stable bonding. The presence of silicon on treated surfaces, as detected by FT-IR, supports this mechanism. The control group showed slightly higher bond strength, but the treated groups remained within acceptable ranges. The authors emphasize that this method could simplify clinical protocols for ceramic bonding. They also note that further research may be needed to confirm long-term performance in clinical settings.