| Budget Amount *help |
¥7,500,000 (Direct Cost: ¥7,500,000)
Fiscal Year 1997: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1996: ¥7,100,000 (Direct Cost: ¥7,100,000)
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| Research Abstract |
Surface treatment by the use of silver-mirrorreaction : New surface treatment method for promoting the bonding of direct metal restorative materials and tooth substance without cementing agent was applied. The silver-mirror reaction of ammoniacal silver nitrate solution by the use of rducing power of aldehyde group in formaldehyde enabled on the tooth surface at the room temperature and short time. As the resuts of metallic silver, which phates out on the tooth surface, reacts with mercury and/or gallium as a liquid metals in the direct methal restorative materials, direct methal restorative materials were fixed tightly without cementing agent on the tooth substance. Furthermore, there is no construction gap at the interface of direct metal restorative materials and tooth substance through metallic silver on the tooth surface.
Improvement of amalgam-bonding method : The compressive shear bond strength (CSBS) of amalgam (Dispersalloy : DA) and gallium alloy (Gallium alloy GF : Ga-GF) wit
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h commercial bonding agents and resin cements to the bovine tooth substance were determined. Especially, it was examined the method of the dentin surface treatment with acid as a hydroxyapatite solubilizer and sodium hypochlorite as a collagen solubilizer. Changing in state from the collagen rich to the hydroxyapatite rich on the dentinal surface took remarkable improvement in adhesion. The CSBS of DA and Ga-GF with Panavia EX (+ Clearfil new bond) to the dentin was 9.7Mpa and 30Mpa, respectively. The relaxation on setting expansion of Ga-GF of the internal stress on the polymerization shrinkage of the resin cement at the interface between resin cement and tooth substance was main reason that could be explained the advantage to Ga-GF to DA in adhesion.
New adhesive monomer : The primer containing N,N'-dimethacryloylcystine, as a multifunctional monomer, with disulfide and carboxyl groups was utilized for surface treatment of tooth hard tissues (enamel and dentin) and dental metal alloys improve the adhesion of bonding agents and resin cements. The primer effectively enhanced the bond strength of Superbond (TBBO iniciator) to precious, semi-precious and nonprecious metal alloys. However, the primer ineffectively enhanced the bond strength to Panavia-21 (ternary iniciator with BPO-amine) to dental metal alloys. Less
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