2014 Volume 57 Issue 1 Pages 73-82
Purpose: It is widely recognized that removal of the smear layer by etching and penetration of resin into decalcified dentin and its polymerization and curing by priming and bonding are necessary to acquire favorable adhesion to dentin. However, these treatments take time and the procedure is complex and technique-sensitive, and thus a simple clinical procedure for composite resin restoration is strongly desired. Self-adhesive composite resin requiring no tooth surface treatment for adhesion would be optimal and particularly useful for the elderly and children; this is a new approach to composite resin restoration.
Considering that it may be clinically applicable as a liner, we prepared trial self-adhesive flowable composite resins using existing flowable composite resins and one-step bonding agents, and evaluated their adhesiveness to human dentin.
Methods: The experimental self-adhesive flowable composite resins were bonded to grinding human dentin and to smear-free dentin, and subjected to micro-vibration. The specimens were stored for 24 hours in distilled water (37°C), then their tensile bond strength was measured. The means and standard deviations were determined for each trial self-adhesive flowable composite resin group.
Results: The mean adhesive strength of self-adhesive flowable composite resin prepared by mixing an existing flowable composite resin (Beautifil Flow F02; 80 wt%, 90 wt%) and solvent-removed one-step bonding agent (BeautiBond; 20 wt%, 10 wt%) was very low (2 MPa or lower), whereas that of self-adhesive flowable composite resin (trial 6) prepared by mixing self-adhesive composite resin with a solvent-removed one-step bonding agent Bond Force at 50 wt% and 50 wt% inorganic filler was 5.26 MPa, similar to that (5.62 MPa) of Fusio Liquid Dentin sold in the U.S., and the pH of these in contact with moisture was less than 3.0. In addition, the adhesive strength of various trial self-adhesive resins after removal of the smear layer from the adhered surface tended to increase, and that of Bond Force at 50 wt% and 50 wt% inorganic filler was 6.49 MPa. Furthermore, when micro-vibration was added to the mixing self-adhesive composite resin with a solvent-removed Clearfil Tri-s Bond at 50 wt% and 50 wt% inorganic filler, the mean adhesive strength was 6.55 MPa.
Conclusion: It is suggested that the adhesive strength of trial self-adhesive flowable composite resins prepared with two commercial one-step bonding agents (Bond Force and Clearfil Tri-s Bond) is sufficient for clinical application as a liner.
