Influence of Light Irradiation Technique on Resin Hardness and Polymerization Shrinkage

Research Project

Project/Area Number	63480426
Research Category	Grant-in-Aid for General Scientific Research (B)
Allocation Type	Single-year Grants
Research Field	Conservative dentistry
Research Institution	Nihon University School of Dentistry
Principal Investigator	ONOSE Hideo Nihon Univ. Dent., Professor, 歯学部, 教授 (70059426)
Co-Investigator(Kenkyū-buntansha)	MASUTANI Shigeyuki Nihon Univ. Dent., Assistant, 歯学部, 助手 (40157201) ANDO Susumu Nihon Univ. Dent., Lecturer, 歯学部, 講師 (40120365)
Project Period (FY)	1988 – 1989
Project Status	Completed (Fiscal Year 1989)
Budget Amount *help	¥5,100,000 (Direct Cost: ¥5,100,000) Fiscal Year 1989: ¥2,000,000 (Direct Cost: ¥2,000,000) Fiscal Year 1988: ¥3,100,000 (Direct Cost: ¥3,100,000)
Keywords	Light Cured Composite Resin / Codition of Light Irradiation / Polymerization.Hardness / Polymerization Shrinkage / Argon ion laser / Dilatometer / Knoop Hardness Numbers / ディラトメーター / アルゴンイオンレーザー / スープ硬さ
Research Abstract	The purpose of this research was to determine the correlation between the polymerization shrinkage and the relative degree of cure of light cured composite resins, we made some experiments. The findings were as follows: 1. The volumetric polymerization shrinkage of light cured composite resin products : The volumetric polymerization shrinkage of light cured composite resin products were measured immediately after light irradiation employed the continuously monitoring dilatometer system. The correlation between the polymerization shrinkage and the coefficient of volumetric changes of composite resins was found. 2. Effect of clinical factors on volumetric polymerization shrinkage of light cured composite resins : Followed the findings of 1., some of the resin products were employed to determine the effect of clinical factors on volumetric polymerization shrinkage. Employed clinical factors were irradiation time, distance between the tip end of light source and composite resin, light intensity, volume of composite resins, and color of composite resins. The coefficient of volumetric polymerization shrinkage was effected by the amount and the degree of polymerization of base resin or matrix resin. 3. The correlation between the degree of polymerization and the volumetric polymerization shrinkage : Followed the findings of 2., factors affecting on the degree of polymerization of composite resins were examined. Volumetric polymerization shrinkage as parameters of the relative degree of cure was affected by the irradiation conditions, light intensity and irradiation time. Each composite resins had their own optimum irradiation conditions to increase the relative degree of polymerization and to decrease the coefficient of volumetric polymerization shrinkage. The technique used in this research was found to be a useful method to determine the correlation between the relative degree of polymerization and the coefficient of volumetric polymerization shrinkage.