<p>Surface Treatment Of Nanozirconia Fillers To Strengthen Dental Bisphenol A–Glycidyl Methacrylate–Based Resin Composites</p>

Abstract

Purpose: To investigate the effects of nanozirconia fillers conditioned with 10-methacryloyloxydecyl dihydrogen phosphate (MDP) with or without zirconium hydroxide precoating on bending strength, Vickers hardness, and translucence of dental resin composites. Methods: We obtained nanozirconia fillers coated with different concentrations of Zr(OH) 4 using wet-chemical synthesis. We analyzed coating quality by observing electron-diffraction patterns using transmission electron microscopy. We conditioned zirconia fillers, with or without prior Zr(OH) 4-coating, using MDP-containing primers and evaluated the formation of chemical bonds using nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS). We then performed three-point bending-strength tests, Weibull analysis, Vickers hardness, and translucence-parameter analysis with or without addition of different concentrations of zirconia using untreated zirconia fillers as controls. Results: We achieved desirable Zr(OH) 4 coating using 5 mmol/L zirconium chloride. NMR and XPS analysis detected stronger Zr-O-P peaks on MDP-conditioned zirconia fillers with prior Zr(OH) 4-coating compared with MDP-conditioned fillers alone, suggesting that MDP bonding with zirconia was enhanced by zirconium hydroxide. Our three-point bending-strength tests revealed that increasing levels of untreated zirconia fillers decreased the three-point bending strength of the resin composites, while MDP-conditioned zirconia fillers with or without prior Zr(OH) 4 coating improved three-point bending strengths. Adding 5 wt% and 7.5 wt% MDP-conditioned zirconia fillers with prior Zr(OH) 4 coating achieved the highest three-point bending strength. Furthermore, addition of zirconia fillers decreased the translucence of silica-based resin composites. Conclusion: MDP conditioning with prior Zr(OH) 4 coating is recommended for treating nanozirconia fillers of resin composites.

<p>Mechanical Properties of Nanohybrid Resin Composites Containing Various Mass Fractions of Modified Zirconia Particles</p>

“…MDP primer was prepared with the following formulation: 18 10 wt% MDP, 88.8 wt% ethanol, 0.3 wt% camphorquinone (Aladdin, China) and 0.9 wt% 4-dimethylamino-benzoic acid ethyl ester (EDMAB) (Aladdin, China). Nano-and micro-zirconia particles (Ruiteng Alloy Materials Co., Ltd., China) were immersed in the MDP primer at a concentration of 1 g/mL and then dispersed ultrasonically for 10 min for a complete reaction.…”

“…Its components were Bis-GMA:TEGDMA (7:3 ratio) co-monomer, camphorquinone (0.5 wt%) as the photosensitizer, and dimethyl-p-toluidine (1 wt%) as co-initiator. 18 The dual-cured groups configured two resin pastes containing the following ingredients: 29 The base paste was Bis-GMA:TEGDMA (7:3 ratio) co-monomer, camphorquinone (0.5 wt%) as the photosensitizer, and dimethyl-p-toluidine (1 wt%) as the co-initiator. The catalyst paste was Bis-GMA:TEGDMA (7:3 ratio) co-monomer and benzoyl peroxide (0.5 wt%) as self-polymerization promoter.…”

“…The cytotoxicity grade was Grade 1, and the resin material had no significant cell cytotoxicity. 18 Figure 9 shows the growth status of cells in each group after 1, 3, and 5 days. The cell morphology was basically normal, and the growth trend was similar.…”

“…15,16 They show effectiveness at enhancing flexural strength and wear resistance. 17,18 However, surface treatment of inorganic fillers can improve the dispersion of the fillers in the matrix and strengthen the combination of the fillers and the matrix. The chemical bonds with the resin matrix need to be strengthened because inorganic fillers fail to form chemical bonds with an organic resin matrix at the microscopic level.…”

“…[22][23][24] Recent studies confirmed that Bis-GMA and UDMA resin composites with a bit MDP-conditioned nano-zirconia fillers could obtain superior flexural strength, elastic modulus and surface hardness in vitro, versus resin composites with unconditioned zirconia fillers. 17,18,25 This surface treatment similar to the silanization of silica fillers can lead to nano-or micro-zirconia fillers as the main fillers of resin composites.…”