Degradation-stage Effect of Self-etching Primer on Dentin Bond Durability

Abstract

It is well-known that self-etching primers can be altered. However, the effects from altered primers on the dentin bond durability have yet to be thoroughly identified. In this study, we examined the effects from 5 altered Liquid A primers in different stages of degradation-where 2-hydroxyethylmethacrylate (HEMA) and 10-methacryloyloxydecyl dihydrogen phosphate (MDP), used in Liquid A primers, were altered by the hydrolysis of the methacryloxy ester portion in the HEMA and MDP-on the hybrid layer's quality and dentin bond durability. The hypothesis was that degradation stages of altered Liquid A primers have no effect on the hybrid layer's quality and on dentin bond durability. Bond strengths, obtained after thermo-cycling, were strongly dependent on the degradation stage of the altered Liquid A primer. Alterations of self-etching primers reduced dentin bond durability and decreased the created hybrid layer's quality.

Influence of Storage Conditions of Adhesive Vials on Dentin Bond Strength

“…It has been reported that the shelf life stability problem of adhesives is not limited to acidic functional monomers; HEMA is also prone to degradation. 17 This monomer acts as a wetting agent that helps resin monomers diffuse into the dentin substrate and it has an ability to react with collagen fibrils. Hydrolysis of the monomers changes their chemical composition, leading to loss of their clinical function with prolonged storage.…”

Development of a self-etching primer with higher shelf life and greater dentin bond stability

“…Significance for all statistical tests was predominately at p<0.05. Figures 2, 3 and 4 show the expanded 13 C NMR spectra of the carbonyl and methylene regions of the designed MEP-NMGly, MDP-NMGly and NMEP-NMGly primers under different storage period conditions, and the NMR peak assignments of the carbons attributed to each acidic methacrylate monomer, NMGly and by-products, as produced by the hydrolysis of these monomers, respectively [3][4][5][6][7][8][9]11) . As shown in Figure 2, when the MEP-NMGly primer, which utilized a water-soluble acidic methacryl ester monomer, MEP, was altered, new NMR peaks, assigned to the methacrylic acid, MA (NMR peaks "α" 73 ppm]) were detected.…”

“…This decrease might be due to the produced byproducts that resulted in a decrease in the quality of the hybrid layer created at the resin-dentin interface 3,4) . However, further decreases in the mean bond strength were not observed, even though the MEP had completely hydrolyzed and the amounts of produced EG and phosphoric acid had increased (storage period=14 weeks).…”

“…It is well understood that the bond strength of resin to the dentin, conditioned by the stored self-etching primers, decreases [1][2][3][4] . This reduction in bond strength is due to the self-etching primers becoming altered during the primer's storage periods, since the acidic and hydrophilic methacryl ester monomers utilized in the self-etching primers had hydrolyzed [3][4][5][6] .…”

“…This reduction in bond strength is due to the self-etching primers becoming altered during the primer's storage periods, since the acidic and hydrophilic methacryl ester monomers utilized in the self-etching primers had hydrolyzed [3][4][5][6] . Previously, Nishiyama et al 7) examined the hydrolytic stability of hydrophilic methacryl ester monomer, 2-hydroxyethyl methacrylate (HEMA), and hydrophilic methacryl amide monomer, N-methacryloyl glycine (NMGly) 8,9) .…”