Improved photochemical bonding of composites to dentin using 4‐methacryloxyethyl trimellitate anhydride

Abstract

The main objective was to evaluate the use of 4-methacryloxyethyl trimellitate anhydride (4-META) to improve bonding of composite materials to dentin. Bowen's resin, containing camphoroquinone, was polymerized by exposure to visible light. In composites, made with a silanated silicate, inclusion of 4-META (3%) had little effect in increasing mechanical strength or adhesion to bovine teeth. However, direct application of 4-META via acetone solution was found to be an effective way of increasing tensile adhesive strength; by 240% to dentin (to 7.2 MPa) and by 160% to enamel (to 10.8 MPa). Applying the experience mentioned above, 4-META was used to bond a proprietary photocuring microfilled composite material to Class V cavities in freshly extracted human teeth. After thermal cycling between water baths held at 5 degrees C and 60 degrees C, all dentin restorations without 4-META failed, as judged by marginal leakage of a dyestuff. In contrast, using 4-META there was no leakage in 9 out of 10 cases. In restorations involving enamel, 4-META failed to prevent marginal leakage at the enamel margins but did prevent penetration along the dentin/composite interface. It is concluded that 4-META shows great promise for preventing marginal leakage at dentin/composite interfaces.

Correlation between degree of conversion, filler concentration and mechanical properties of posterior composite resins

“…Positive correlations between elastic modulus, proportional limit, tensile strength and filler concentration were observed during an investigation of the mechanical properties of dental composites (Boyer, Chalkley & Chan, 1982); a small negative correlation was also found between the compressive strength and the filler content in a study of 10 commercial composites, all of which were Bis-GMA-or UEDMA-based resins with filler loadings of 20-65% by volume. Nagata, Lundeen and Turner (1984) revealed that maximum diametral tensile strength (55 MPa) occurred with 75% by weight filler content, and maximum compressive strength (315 MPa) with 80% by weight filler content, in Bis-GMA-based dental composites.…”

Evaluation of two rehydration protocols for fractured tooth fragments for characteristics of penetration of resin tags using confocal laser scanning microscopy

“…The entire bonding interface was termed the "hybridization zone" and theorized to be responsible for the micromechanical bonding of the composite resin. 12 On the contrary, dehydration of the dentinal tubules did not allow deeper penetration of the bonding agent and resulted in weaker bonds. The role of rehydration was not emphasized in the bonding of the resin to the fractured enamel.…”

“…This resulted in the formation of tags after curing and later facilitated the penetration of the composite resin into the region. The entire bonding interface was termed the “hybridization zone” and theorized to be responsible for the micromechanical bonding of the composite resin 12 . On the contrary, dehydration of the dentinal tubules did not allow deeper penetration of the bonding agent and resulted in weaker bonds.…”