New Self-Etching Glass-Ceramic Primer: Innovative Alternative for Glass-Ceramic Conditioning

Objectives: The clinically recognized procedure to achieve a strong and durable bond to glass-ceramics involves HF-etching & silanization. Silanization is responsible for chemical bond formation, while HF-etching creates micromechanical interlocking. However, HF poses handling issues due to its toxicity and capacity to over-etch glass-ceramics, requiring the development of less toxic and aggressive alternatives. Although HF-substitutes have been already reported in the literature, HF-etching remains the gold-standard for glass-ceramic conditioning.

To overcome HF-etching drawbacks, a self-etching glass-ceramic primer (Monobond Etch&Prime/MBEP/Ivoclar-Vivadent), combining a HF-free etchant and silane-system, was developed. This new HF-free-system is able to etch & prime all commercial glass-ceramics in a single step and application-procedure.

This study investigates MBEP-etching & -bonding performances to commercial glass-ceramics using scanning-electron-microscopy (SEM) and tensile-bond-strength (TBS).
Methods: The following glass-ceramics were selected: lithium-disilicate & leucite (e.maxCAD & EmpressCAD/Ivoclar-Vivadent), lithium-metasilicate (Celtra/Dentsply), feldspar (MarkII/Vita).
Glass-ceramics were allocated into two groups regarding surface-treatment. Group 1 (HF/MBP) was used as reference: the surface was treated with hydrofluoric acid (HF/application-time according to ceramic-IFU/5%HF-gel/Ivoclar-Vivadent) followed by Monobond Plus (MBP for 60s/Ivoclar-Vivadent). Group 2 (MBEP) was treated with Monobond Etch&Prime (MBEP for 60s/Ivoclar-Vivadent). TBS was investigated with Multilink Automix and Variolink EstheticDC (MLAM & VE, Ivoclar-Vivadent). Two different aging-procedures were tested: 24h@37°C and 10’000 thermocycles (10kTC/5-55°C/30s). Morphology of etched surfaces was examined by SEM.
Results: For results see the table below.

MBEP- and HF/MBP-groups demonstrated comparable TBS-values to all tested glass-ceramics.
SEM revealed that MBEP generates a less pronounced etch-pattern than HF.
Conclusions: MBEP showed comparable bonding performances to the well-established-system HF/MBP. This new HF-free-system allows conditioning of all commercial glass-ceramics in a simple & safe application-procedure.