Micro-shear bond strength of a novel resin-modified glass ionomer luting cement (eRMGIC) functionalized with organophosphorus monomer to different dental substrates

Abstract

Objectives: This study aims to assess and compare the micro-shear bond strength (μSBS) of a novel resin-modified glass-ionomer luting cement functionalized with a methacrylate co-monomer containing a phosphoric acid group, 30 wt% 2-(methacryloxy) ethyl phosphate (2-MEP), with different substrates (dentin, enamel, zirconia, and base metal alloy). This assessment is conducted in comparison with conventional resin-modified glass ionomer cement and self-adhesive resin cement.

Materials and methods: In this in vitro study, ninety-six specimens were prepared and categorized into four groups: enamel (A), dentin (B), zirconia (C), and base metal alloys (D). Enamel (E) and dentin (D) specimens were obtained from 30 human maxillary first premolars extracted during orthodontic treatment. For zirconia and metal alloys, 48 disks were manufactured using IPS e.max ZirCAD through dry milling and Co-Cr powder alloy by selective laser milling. Each group was further subdivided into three subgroups (n = 8) according to the luting cement used: (1) Fuji PLUS resin-modified glass ionomer luting cement (FP) as a control cement, (2) modified control cement (eRMGIC), and (3) RelyX U 200 (RU 200) self-adhesive resin cement. The two-way analysis of variance and Tukey's HSD were used to assess the data obtained from measuring the μSBS of the samples.

Results: The results of this study showed that the mean μSBS values of eRMGIC were statistically higher compared to FP in all tested groups (p < 0.001). The mean μSBS results of eRMGIC were non-significantly different from those recorded by RU 200 for all substrates except for the dentin substrate, where the RU200 cement produced significantly higher strength (p < 0.001). The failure modes were limited to a combination of mixed and adhesive failures without pure cohesive failure.

Significance: The functionalization of FP with an organophosphorus co-monomer (2-MEP) directly affects the adhesion performance of the functionalized cement, which may be utilized to develop a new type of acid-base cement. It exhibited a performance comparable to that of resin-based cement and should serve well under different clinical conditions.

Keywords: Luting resin cement; Microshear bond strength; Phosphate functional monomers; Resin-modified glass ionomer luting cement.

Fig. 1

Preparation of enamel slabs (A): Root was excised. (B): The crown separated longitudinally into the buccal and palatal parts. (C): The buccal and palatal surfaces. (D): Four sections of enamel slabs.

Fig. 2

Enamel sample preparation. (A): Enamel slaps. (B): Enamel slap with a metal rod. (C): Slaps attached to the vertical arm of dental surveyor. (D): Sample insertion into the silicone mold.

Fig. 3

Different samples used in this study.

Fig. 4

Teflon Mold (A): Full view. (B): Bottom view. (C): Sample in place. (D): Top view of sample. (E): Side view of the sample with cement material within the polyethene microtubules. (F): Cement sample free from polyethylene microtubules.

Fig. 5

Micro-Shear Test, Custom-made chisel specially designed for micro shear samples illustrates the micro shear test chisel, acrylic block with cement sample on Zirconia substrate.

Fig. 6

Average μSBS (micro-shear bond strength) values in MPa for several luting cements when applied to different substrates and stored for 24 h in distilled water.

Fig. 7

Distribution of failure patterns in different specimen groups.

Fig. 8

Scanning electron micrographs of failure modes for different substrates at × 80 magnification and working distance of 10–15.1 mm. A. Adhesive failure mode of control cement FP on metal substrate (red circle); B. Mixed mainly cohesive failure mode of experimental cement eRMGIC on enamel substrate; C. Mixed mainly adhesive failure mode of experimental cement on metal substrate; D. Adhesive failure mode of experimental cement eRMGIC on dentin substrate; and E. Mixed mainly cohesive failure mode of RU 200 on zirconia substrate. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)