4-acryloxyethyltrimellitic-acid and hydroxyethyl-methacrylate

The aims of this study were to investigate the photoinitiation behaviors of acylphosphine oxide (APO) and bisacylphosphine oxide (BAPO) derivatives in comparison to D,L-camphorquinone (CQ)/tertiary amine (EDAB) system. Fifty six kinds of experimental unfilled, light-cured resins were prepared using APO, BAPO, CQ, EDAB, resin monomers, and adhesive monomers. The measurements of ultraviolet-visible (UV-VIS) spectroscopy, photopolymerization with differential scanning calorimeter (photo-DSC) and degree of conversion (DC) determination were performed. Results showed that the UV-VIS spectra of all APO and BAPO derivatives possessed lambda max ranging between 365 and 416 nm. Their photoinitiation behaviors were not influenced by acidic adhesive monomers formulated in unfilled Bis-GMA-based resins (p < 0.05). Although BAPO exhibited higher reactivity than CQ/EDAB in unfilled 6-methacryloyloxyhexcyl phosphonoacetate (6-MHPA)/ 2-hydroxyethyl methacrylate (HEMA) and 6-MHPA/glycerol monomethacrylate (GM)-based resins, it was found that there were no statistically significant differences in DC (%) between BAPO [44.2(6.5)-51.2(4.3)] and CQ/EDAB [42.4(4.4)-47.5(3.7)] (p < 0.05). It was concluded that APO and BAPO photoinitiators exhibited reactivity comparable to that of CQ/tertiary amine system.

Topics: Bisphenol A-Glycidyl Methacrylate; Calorimetry, Differential Scanning; Composite Resins; Dental Materials; Humans; Light; Materials Testing; Methacrylates; Phosphines; Phosphonoacetic Acid; Polyethylene Glycols; Polymers; Polymethacrylic Acids; Spectrophotometry, Ultraviolet; Terpenes; Tricarboxylic Acids

Reactmer Bond (Shofu Inc., Kyoto, Japan) is a glass ionomer (GI) based, tri-curable, all-in-one, filled adhesive. Both fluoroaluminosilicate glass (FASG) and fully pre-reacted glass (F-PRG) are used as fillers. This study examined the ultrastructure and elemental composition of resin-dentine interfaces that were treated with this adhesive.. Dentine disks prepared from human third molars were abraded with either 600- or 60-grit SiC paper to create smear layers of different thickness. They were bonded using Reactmer Bond. Cryo-fractured dentine surfaces devoid of smear layers were also bonded by chemical-activation and GI reaction without additional light-activation, or allowing the GI reaction to proceed for 1min before the adhesive was applied and light-activated. Undemineralised and demineralised sections were processed for TEM examination and STEM/EDX analysis.. Resin-dentine interface from specimens with smear layers consisted of a mineral-dense surface layer that resided on top of a partially demineralised dentine. The partially demineralised zone was considerably thicker in the 600-grit than the 60-grit specimens. In smear layer-free specimens that were cured by chemical-activation/GI modes only, the surface layer concurred with the partially demineralised zone, and appeared as an electron-dense layer over the undemineralised intact dentine. Smear layer-free specimens that were cured by the light-activation of the partially neutralised adhesive contained incomplete amorphous surface layers only. Apart from colloidal silica, FASG fillers were the predominant filler type within the resin matrices. Peripheral hydrogel layers that contained electron-dense "seeds" were found around the FASG fillers. F-PRG fillers were only sparsely observed. In specimens that were laboratory demineralised with formic acid, phase separation of the unstained resin matrices into electron-dense and electron-lucent domains occurred. Artefactual dendritic deposits were found within the electron-dense domains.. The presence of a surface interaction layer on top of a partially demineralised zone along the resin-dentine interface suggests that either a GI-type reaction or precipitation of insoluble carboxylate salts around remnant apatite crystallites may occur when this single-step adhesive interacts with dentine. Appearance of artefactual dendritic deposits suggests that continuous ion movement is possible within the hydrophilic portion of the resin matrix in this fluoride-releasing adhesive.

Topics: Aluminum Compounds; Apatites; Artifacts; Carbon Compounds, Inorganic; Carboxylic Acids; Chemical Precipitation; Dental Bonding; Dentin; Dentin-Bonding Agents; Electron Probe Microanalysis; Fluorides; Formates; Glass Ionomer Cements; Humans; Hydrogel, Polyethylene Glycol Dimethacrylate; Light; Methacrylates; Microscopy, Electron; Microscopy, Electron, Scanning; Polyurethanes; Silicon Compounds; Silicon Dioxide; Smear Layer; Surface Properties; Tricarboxylic Acids

The purpose of this study was to investigate the rate of development of dentin bond strengths of resin-modified glass-ionomer cements (RMGIC) with use of dentin primers. The prepared dentin surface was treated according to each manufacturer's instruction or the dentin primer. Cements were condensed into a vinyl mold and light activated. The shear bond strengths were measured at a crosshead speed of 1.0 mm/min after 1, 5, 10, 30, 60 min, 2, 5, and 24 h storage in water at 37 degrees C. Presence of a significant difference between the mean bond strength at 1 min and each of the other test times was analyzed. The first time at which there was a significant increase in bond strength was defined as the "initial increasing time". As compared with the manufacturer's suggested dentin treatments, the bond strengths increased significantly when the dentin primers were used. The initial increasing times when the specimens were made following each manufacturer's instructions were 10 approximately 60 min. When dentin primer was used, the initial increasing time shortened to 5 approximately 10 min. It was concluded that the use of dentin primers for RMGIC restorations resulted in reduction of the initial increasing time.

Topics: Acrylic Resins; Animals; Cattle; Composite Resins; Dental Bonding; Dental Cements; Dentin; Dentin-Bonding Agents; Fluorides, Topical; Glass Ionomer Cements; Materials Testing; Methacrylates; Methylmethacrylates; Phthalic Acids; Resin Cements; Resins, Synthetic; Stress, Mechanical; Time Factors; Tricarboxylic Acids; Water

To develop a self-etching primer for ground dentin, 4-acryloxyethyltrimellitic acid (4-AET) was newly synthesized, and the effect of concentrations varying from 0 (control) to 56.5 wt% 4-AET in the water/ HEMA primer on bonding to the dentin was investigated. Bond strength to the dentin was significantly affected by the inclusion of 4-AET in the primer which also contained N,N-di(hydroxyethyl)-p-toluidine (DEPT) when compared with the control (0% 4-AET) (p < 0.01). The optimum 4-AET-concentration and the mean bond strength (SD) were found to be 6.5 wt%: 24.2 (3.6 MPa, 37.4 wt%: 25.3 (4.4) MPa, 47.2 wt%: 26.9 (11.6) MPa and 54.4 wt%: 29.7 (12.9) MPa. The role of DEPT in the 4-AET/HEMA primer was assessed, and the optimum DEPT-concentration was found to be 0.154 and 0.307 mol%. Regarding the hypothetical bonding mechanism to dentin, it was thought that the ionized 4-AET in water/HEMA would penetrate into dentin substrates, and DEPT as an accelerator in situ would facilitate photo-polymerization at the dentin-resin interface, and result in increased bond strength to ground dentin.

Topics: Analysis of Variance; Animals; Cattle; Dental Bonding; Dentin-Bonding Agents; Materials Testing; Methacrylates; Polymers; Toluidines; Tricarboxylic Acids; Water

The effect of the inclusion of aminobenzoic acid derivatives (ABAD) in a self-etching primer comprising 4-acryloxyethyltrimellitic acid (4-AET), HEMA and water on shear bond strength to ground dentin was investigated. The mean bond strengths to dentin were significantly increased by the inclusion of 0.307 mol% ABAD in the 4-AET/HEMA primer, when compared with the control (0 wt% ABAD) (p < 0.01). A particularly high value (38.0 MPa) of shear bond strength was obtained in the use of the primer containing p-nitroanthranilic acid (p-NAA). It seemed to assume that the effect of p-NAA could be caused by the strong electron-withdrawing group of -NO2. From SEM observation, it was found that bonding resin appeared to adhere strongly to the ground dentin without formation of any resin-tags in the dentinal tubules. It was thought that the ABAD with 4-AET/HEMA could perform facilitating photo-polymerization at the bonding interface, and resulted in increased bond strength to ground dentin, and that the bond strength could be affected by the electronegativities of substitutional groups of ABAD.

Topics: 4-Aminobenzoic Acid; Analysis of Variance; Animals; Cattle; Dental Bonding; Dentin-Bonding Agents; Materials Testing; Methacrylates; Microscopy, Electron, Scanning; ortho-Aminobenzoates; para-Aminobenzoates; Tricarboxylic Acids