Optimizing glass-ceramic bonding incorporating new silane technology in an experimental universal adhesive...

Bonding glass-ceramic restorations to tooth structures remains a clinical challenge. Traditional methods require separate silanization steps, which can be time-consuming and prone to error. Prior research has shown that silane-coupling agents are unstable in acidic environments, limiting their integration into universal adhesives (UAs). This gap motivated the development of new silane technologies that could function within UAs without requiring additional steps. Existing studies have demonstrated that tribochemical silica coating and hydrofluoric acid etching improve bonding surfaces, but these methods still require silanization for optimal results. No prior work had resolved how to embed stable silane into UAs. This uncertainty drove the current investigation into whether a new silane formulation could bypass the need for separate silanization. The study sought to determine if a combined silane approach could enhance bonding without compromising durability. This paper addresses the unresolved issue of silane integration into UAs for glass-ceramic bonding.

The aim of this study was to assess whether a new silane technology could be incorporated into a universal adhesive to bond glass-ceramic restorations without requiring a separate silanization step. The researchers focused on evaluating the effectiveness of a combined silane system consisting of 3-(aminopropyl)triethoxysilane (APTES) and γ-methacryloxypropyltriethoxysilane (γMPTES) in an experimental adhesive formulation. The goal was to determine if this formulation could outperform existing adhesives in terms of bond strength. The study also sought to compare the performance of the new adhesive on different surface treatments of glass-ceramic blocks. The motivation stemmed from the clinical need for a simplified bonding protocol that maintains high durability. The researchers proposed that the new silane technology could stabilize within the adhesive and function effectively in acidic conditions. This approach could potentially eliminate the need for separate silanization in clinical settings.

The experimental adhesive, ADH-XTE, was formulated with a combination of APTES and γMPTES silane technology. The adhesive was tested on four types of glass-ceramic CAD/CAM blocks: as-milled (AM), tribochemical silica-coated (TSC), hydrofluoric acid-etched (HF), and mirror-polished (MP). Bond strength was measured using immediate and aged shear bond strength (SBS) tests with 10 specimens per group. The control adhesives included Scotchbond Universal (SBU) and Scotchbond 1 XT (SB1-XT). The study compared the performance of ADH-XTE with and without prior silanization. Surface topography and fracture patterns of debonded specimens were analyzed using scanning electron microscopy (SEM). The experimental adhesive was tested under both immediate and aged conditions to assess long-term stability. This approach allowed the researchers to evaluate the effectiveness of the new silane technology in different surface conditions.

The experimental adhesive ADH-XTE demonstrated significantly higher bond strength to glass-ceramic surfaces compared to its silane-containing SBU precursor when used without separate silanization. The bond strength of ADH-XTE was comparable to SBU when silanization was applied separately. However, after aging, a significant reduction in bond strength was observed on TSC surfaces (p < 0.05), but not on HF-etched surfaces. The lowest bond strength was recorded on AM and MP surfaces when no silanization was performed (p < 0.05). SEM analysis revealed differences in surface topography and fracture patterns depending on the treatment method. The combined APTES/γMPTES silane system in ADH-XTE showed superior bonding capacity compared to the SBU adhesive. The results suggest that the new silane technology can function effectively within a universal adhesive formulation. These findings indicate that the new adhesive may offer a simplified bonding protocol for glass-ceramic restorations.

The study concluded that the experimental adhesive ADH-XTE, containing a combined APTES/γMPTES silane system, outperformed its silane-containing SBU precursor in bonding to glass-ceramic surfaces without the need for separate silanization. The adhesive performed equally well as SBU when silanization was applied separately. However, aging reduced bond strength on TSC surfaces but not on HF-etched ones. The lowest bond strength was observed on AM and MP surfaces when silanization was omitted. The results suggest that the new silane technology can function effectively within a universal adhesive formulation. The study did not propose that silanization is unnecessary in all cases, as HF etching remained essential for durable bonding. The findings support the potential of the new silane technology to simplify clinical protocols. The authors emphasized the importance of surface preparation in achieving optimal bond strength.