Influence of application mode of universal adhesive on the surface morphology, elemental composition and bond strength of calcium silicate-based cements to composite resin: a SEM-EDX microanalysis study

Abstract

Maintaining pulp vitality is one of the most important issues in dentistry and the quality of the bond strength of calcium silicate-based cements (CSCs) used for this purpose to restorative material directly affects the long-term success of the treatment. This in vitro study aimed to evaluate microshear bond strength (µSBS) of several CSCs to composite resin using a universal adhesive in both etch-and-rinse and self-etch modes and to examine surface characteristics after acid etching. Five CSCs, namely Angelus MTA, Biodentine, NeoMTA, TheraCal LC, and Well Root ST were evaluated. Fifteen specimens per group were used for determining the µSBS to composite resin. The composite resin was applied over CSCs using a universal adhesive either in etch-and-rinse or self-etch modes, and µSBS of CSCs to composite resin was assessed. The effect of acid etching on the surface morphology and Ca/Si ratio of CSCs were examined by SEM-EDX microanalysis. The highest µSBS was obtained for TheraCal LC in both etch-and-rinse and self-etch modes. No significant difference was found between Biodentine and MTA-based cements in the etch-and-rinse mode, whereas in the self-etch mode, Biodentine displayed a significantly superior bond strength. The results of SEM demonstrated distinct morphological alterations after acid etching. Acid etching decreased the Ca/Si ratio of the substrate surface by approximately 4-fold for all CSCs. TheraCal LC is more suitable for vital pulp therapy with its superior bond strength to composite resin. Furthermore, it may be suggested that adequate adhesive performance may also be achieved without an acid etching.