RESUMO
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.
RESUMO
AIM: To evaluate and compare the marginal adaptation and fracture resistance of resin matrix ceramic crowns fabricated using 3-dimensional (3D) printing and computer aided design/computer aided manufacturing (CAD/CAM) milling technology. MATERIALS AND METHODS: Thirty extracted human maxillary first premolars were prepared to receive crown restorations and grouped into 3 groups according to 3 different crown materials (n = 10): VE: teeth restored with milled Vita Enamic, CS: teeth restored with milled Cerasmart 270 and VSC: teeth restored with 3D-printed VarseoSmile Crown Plus. Marginal analysis was performed with the aid of a digital microscope at (230x) magnification, both before and after cementation with self-adhesive resin cement and analyzed with Image J analysis software. The fracture loads for each sample were then recorded using a universal testing machine in a single load-to-failure test up until the crowns failed. RESULTS: The lowest marginal gap values were recorded for VSC before (8.03 µm) and after (15.07 µm) cementation with significant difference compared to the other crown materials (p <0.05), while the differences between the milled groups were non-significant both before, (CS (11.35 µm) and VE (11.86 µm)), and after cementation, (CS (20.01 µm) and VE (21.08 µm)). In terms of fracture resistance, VE recorded significantly lower fracture load values (727.8 N) (p <0.05) than the crowns fabricated from CS (1213.8 N) and VSC (1181.5 N), which showed no statistically significant differences between each other. CONCLUSION: 3D printed definitive crowns outperformed CAD/CAM milled crowns in terms of marginal adaptation, along with comparable fracture resistance values.