Efficacy of new mono-methacrylate esters as a dentin primer

• Project/Area Number: 06671925
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: Conservative dentistry
• Research Institution: Showa University
• Principal Investigator: HASEGAWA Tokuji Showa University, School of Dentistry, Operative Dentistry ; Assistant Professor, 歯学部, 講師 (10180861)
• Co-Investigator(Kenkyū-buntansha): MIYASAKA Tadashi Showa University, School of Pharmaceutical Sciences, Medicinal and Synthetical C, 薬学部, 教授 (70053808)
• Project Period (FY): 1994 – 1995
• Project Status: Completed (Fiscal Year 1995)
• Budget Amount: ¥2,100,000 (Direct Cost: ¥2,100,000); Fiscal Year 1995: ¥700,000 (Direct Cost: ¥700,000); Fiscal Year 1994: ¥1,400,000 (Direct Cost: ¥1,400,000)
• Keywords: Dentin Bonding / Dentin Primer / Esterified Methacrylate / xylitol / Contraction Gap / Tensile Bond Strength / デンティンプライマー / メタクリル酸エステル / NMR(磁気共鳴スペクトル)

Research Abstract

Some esterified methacrylate with polyvalent alcohol such as glyceryl methacrylate and erythritol methacrylate, have been developed and reported as effective dentin primers. The purpose of this study was to synthesize a new esterified methacrylate monomer, xylitol mono-methacrylate (2, 3, 4, 5-tetrahydroxypentyl methacrylate : XM) to avoid the possible side effect on the skin tissue, and to determine the bonding efficacy of the aqueous solution of this monomer.
XM was synthesized by acylation of xylitol with methacryloyl chloride. Powdered xylitol, 4-dimethylaminopyridine (DMAP) and hydroquinone were completely dissolved into pyridine. Freshly distillled methacryloyl chloride was then dropped into the solution under dry argon atmosphere. The XM in the mixture was spread out as a single spot (Rf=0.30) on a TLC plate with the chloroform-ethanol elution [70 : 30]. The dropwise method yields 24.2%. The chemical structure of XM was determined by lnfrared (1R) analysis.
The experimental dentin primers were prepared as aqueous solutions of the XM at the concentration of 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 and 55%. The bonding efficacy of the primers was evaluated by measuring the polymerization contraction gap in a cylindrical dentin cavity and tensile bond strength to flat dentin surface. The cavity walls as well as the flat dentin surface were cleaned with EDTA, primed with the primer and applied the bonding agent (Clearfil Photo Bond) before cavity filling and application of resin composite on the flat dentin. Marginal gaps between the dentin cavity and the resin composite could not observe with the 30 to 50% XM solution. The tensile bond strengths of the primers were 16.5<plus-minus>4.6 MPa [5%], 12.71<plus-minus>3.4 MPa [15%], 14.9<plus-minus>4.6 MPa [25%], 16.8<plus-minus>5.8 MPa [35%], 20.9<plus-minus>4.1 MPa [45%] and 21.6<plus-minus>5.
The aqueous solution of new synthesized monomer (XM) was effective as a dentin primer at the concentration of 30 to 50%. Before clinical more researching effort to the possible side effect on the skin tissue is required.