Comparison of the hybrid layer formed by Silorane adhesive, one-step self-etch and etch and rinse systems using confocal micro-Raman spectroscopy and SEM.
OBJECTIVE
To determine the extent of the hybrid layer (HL) of the novel adhesive system (Silorane, 3M ESPE) compared to one-step and etch and rinse adhesive systems, using 2D confocal micro-Raman spectroscopy and SEM.


METHODS
Silorane adhesive system was compared to two one-step self-etch (G Bond, GC; AdheSE One, Ivoclar Vivadent) and etch and rinse (Excite, Ivoclar Vivadent) as controls. Adhesives were applied to human dentine, cured and sections prepared perpendicular to the flat adhesive-dentine surface. Two-dimensional micro-Raman mapping was performed over 20mumx20mum areas across the adhesive-dentine interface. SEM micrographs of the same specimens were obtained. One-way ANOVA (Tukey's post-test) was used to analyse the differences in HL thickness among the four adhesive systems and the paired t-test to compare the results obtained by micro-Raman and SEM for each adhesive.


RESULTS
Silorane adhesive system formed a HL of comparable thickness to methacrylate-based but thicker than the acrylamide-based one-step self-etch adhesives from SEM analysis. A gradual decrease in adhesive penetration was observed in all systems. A 1-mum zone, between the cured primer and bond was identified by Raman but not visualised on SEM. Compared to SEM, HL calculated from Raman data were always greater.


CONCLUSIONS
Micro-Raman spectroscopy gives a more precise indication of dentine demineralisation and monomer infiltration and highlights the intermediate zone of approximately 1mum between Silorane primer and bond, not visible with SEM at x10,000 magnification. Giving as it does, a compilation of many linear scans it allows HL mean values to be calculated.
The University of Edinburgh, Postgraduate Dental Institute, Lauriston Building (4th floor), Lauriston Place, Edinburgh EH3 9HA, United Kingdom. ariosantini@hotmail.com
Ario
A
Santini
Vesna
V
Miletic
D000134:Acid Etching, Dental / Q000379:methods; D003188:Composite Resins; D001840:Dental Bonding; D017220:Dentin-Bonding Agents; D006801:Humans; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements; D012821:Silanes; D012822:Silicon Dioxide; D062047:Silorane Resins; D013059:Spectrum Analysis, Raman
D003188:Composite Resins; D017220:Dentin-Bonding Agents; D019279:Resin Cements; D012821:Silanes; D062047:Silorane Resins; D012822:Silicon Dioxide