An Experimental Thermally Deposited Coating for Improved Bonding to Glass-fiber Posts

Purpose: To determine whether an experimental thermally deposited siloxane-methacrylate coating for use in industrial scale applications would improve the bond strength of resin-based materials to glass fiber posts (GFPs) without affecting their mechanical properties. Materials and Methods: An experimental 5% (w/v) solution of methacryloxypropyltrimethoxysilane was prepared. Two types of GFPs (Exacto, Angelus; White Post DC, FGM) were divided into the following groups: S: silane; SA: silane and adhesive; HS: 35% H₂O₂ and silane; HSA: 35% H₂O₂, silane and adhesive; Exp: siloxane-methacrylate coating (Si-O) via post immersion in experimental solution followed by heating; Exp-S: silane after Si-O treatment; Exp-A: adhesive after Si-O treatment; and Exp-SA: silane and adhesive after Si-O treatment. The posts were positioned in a mold to allow insertion of a dual-curing resin core, serially sectioned into beams, and subjected to microtensile bond strength (μTSB) testing. The three-point bending test and SEM/EDX analysis were used to assess the mechanical and surface properties of untreated GFPs that were etched with H₂O₂ or treated with Si-O. Results: Surface treatments affected the μTSB only for the Exacto GFPs. The highest μTBS (MPa) was observed in Exp-S and Exp-SA groups, whereas H₂O₂ etching resulted in intermediate values. The mechanical properties were not affected by surface treatments. Exacto GFPs had significantly higher flexural strength (σ_f) and flexural modulus (E_f) than did the White Post DC GFPs, but the latter were significantly stiffer (S) than Exacto, regardless of the surface treatment tested. H₂O₂ promoted morphological changes in post surfaces. The experimental treatment promoted deposition of Si onto the post surface, improving bond strengths of Exacto posts. Conclusion: The proposed novel coating technique is a viable procedure for fiber post manufacturers to improve the μTSB of resin-based materials. Schlagwörter: bond strength, fiber post, hydrogen peroxide etching, silane