Marginal adaptation of commercial compomers in dentin cavity

Synthesis and Evaluation of Novel Bifunctional Oligomer-based Composites for Dental Applications

Five novel bifunctional oligomers containing both carboxylic acid and methacrylate groups are synthesized, characterized, and used to formulate compomers by mixing with strontium fluoroaluminosilicate glass powder at a filler level of 75% (by weight). Compressive strength (CS) of the cements and viscosity of the resin liquids are used as screening tools to find the optimal formulation. Diametral tensile (DTS) and flexural strengths (FS) are also determined. Results show that the oligomers derivatized with glycerol dimethacrylate exhibit higher CS than those with 2-hydroxyethyl methacrylate. The CS increases with increasing diluent content, filler level, and light-exposure time. During aging, the cement shows an increase of strength over 24 h and then remains unaltered for up to 3 months. The experimental compomer is 45 and 69% higher in CS, 35 and 174% higher in DTS, and 39 and 170% higher in FS, respectively, as compared to Dyract and Fuji II LC.

The efficacy of dentine adhesive to sclerotic dentine

OBJECTIVE

To evaluate the effect of a dentine bonding system to sclerotic dentine in comparison with normal dentine.

METHODS

The efficacy of the dentine bonding system to sclerotic dentine was examined by measuring wall-to-wall polymerization contraction gap width. The dentine cavity wall was pretreated with an experimental dentine bonding system with and without a dentine primer. The dentine primer was glyceryl mono-methacrylate (Blemmer GLM, NOF Corp., Tokyo, Japan) (GM), which contained esterified methacrylate with a polyvalent alcohol, which is similar to 2-HEMA. The structure of sclerotic dentine and the changes to that structure caused by etching were observed using a scanning electron microscope (SEM).

RESULTS

With GM priming, complete marginal integrity was obtained regardless of the type of dentine. Without GM priming, complete marginal integrity was obtained in half of the specimens of the sclerotic dentine, and was not obtained in any of the specimens of normal dentine. In the SEM study, the structure of sclerotic dentine was considered to be viable for adhesion. However, this was not the case when etched with phosphoric acid.

CONCLUSION

It was concluded that sclerotic dentine had a clear advantage over normal dentine with regard to the adaptation of resin composites. Therefore the structure of sclerotic dentine possesses a naturally derived structure to which a primer may attach. Sclerotic dentine is part of the body's natural defenses and should be preserved. It should not be exposed to acid etching which would damage its structure.