Restorative resins: hardness and strength vs. quantity of remaining double bonds

Abstract

– It has been hypothesized that the Wallace indentation hardness of smooth surface resins is a factor of prime importance for the abrasion by food of Glass 1 restorations. In the present work factors affecting the hardness of polymers were investigated. In addition the tensile strength of composite resins was measured and related to the catalytic system of the polymer. It was found that for a given composition of the monomer the Wallace hardness number increased with increasing content of inhibitor, decreased with increasing content of peroxide, and was unaffected by changes in the content of amine. The hardness was well correlated with the quantity of double bonds remaining in the polymer. BISGMA‐based polymers showed no variation in hardness when the originating monomer varied with respect to content of a bi‐ or a trifunctional diluting monomer. Light‐polymerized polymers were relatively hard as compared to chemically cured materials of adequate setting time. The tensile strength of composite resins was predominandy determined by the monomer content of peroxide and increased herewith. The tensile strength was well correlated with the quantity of remaining double bonds in the constituting polymer.

Effect of the increase of energy density on knoop hardness of dental composites light-cured by conventional QTH, LED and xenon plasma arc

“…The hardness of composites is influenced by several factors, such as organic matrix composition (14), type and amount of filler particles (15) and degree of conversion (16). In this study, the Knoop hardness of Z250 was higher than that of Esthet-X.…”

Resin Infiltration of Artificial Enamel Caries Lesions with Experimental Light Curing Resins

“…At this juncture, it must be pointed that increasing the amount of TEGDMA in BISGMA/ TEGDMA comonomers has been shown to lead to higher polymerization shrinkage 20) and brittleness 21) . Moreover, enzymatic hydrolysis stability seems to decrease with increasing TEGDMA content 22) .…”

Dual-curing, self-adhesive resin cement: influence of the polymerization modes on the degree of conversion and microhardness

“…An important aspect to be considered is the monomer's degree of conversion which affects the physico-chemical properties including strength, stiffness, water absorption, biocompatibility as well as color stability. Post-operative sensitivity has also been reported as a possible consequence of inadequate polymerization of the resin cement [2][3][4][5][6][7][8][9][10][11][12][13] . The use of dual-curing resin cements intends to combine chemical and light-polymerization and at the same time allowing polymerization to take place in deeper areas of the tooth cavity applying shorter light irradiation time.…”