1301 In-situ Analysis of Degree of Conversion of 2-step etch-and-rinse Adhesives

Saturday, March 24, 2012: 9:45 a.m. - 11 a.m.
Presentation Type: Poster Session
C.O. NAVARRA, M. CADENARO, G. TURCO, R. DI LENARDA, and L. BRESCHI, Department of Medical Sciences, University of Trieste, Trieste, Italy

To investigate the degree of conversion of the hybrid layer (HL) created by three commercial 2-step etch-and-rinse adhesives. The tested hypothesis was that no difference could be observed within the tested adhesives when applied under simulated pulpal pressure.

Methods: The tested adhesives were SB (Scotchbond 1XT, 3M ESPE), PB (Prime&Bond NT, Dentsply), AM (Ambar, FGM). Adhesives were applied on human dentin disks (N=3) following manufacturers’ instructions under simulated pulpal pressure (20mm H2O). A 2mm-thick composite layer was applied on the adhesive and light cured for 20 s with a quartz-halogen lamp at 600mW/mm2 (Elipar 2500; 3M ESPE). The adhesive interface was exposed for the spectroscopic micro-Raman analysis (Renishaw InVia; laser wl 785 nm). One Raman spectrum was collected every 1µm along the dentin/adhesive interface in the intertubular dentin region. The relative intensities of bands associated with mineral dentin components (PO functional group at 960 cm-1) and adhesive (C=C at 1640 cm-1 as reaction peak, phenyl C=C at 1610 cm-1 as reference peak) across the hybrid layer were used to identify the adhesive layer and calculate the degree of conversion (DC) of the tested adhesives. Data were analyzed by one-way ANOVA (statistical significance was set at p=0.05) and Tukey’s post-hoc.

Results: The DC of the adhesives ranked as follows: SB(79±7%)=AM(78±7%)>PB(65±10%) (p<0.05).

Conclusions: The tested hypothesis was rejected since PB showed lower DC values than SB and AM. An optimal DC is needed to obtain a stable polymeric network and to guarantee the longevity of the adhesive interface. Further studies are needed to investigate the mechanical properties of the hybrid layer created by the tested 2-step etch-and-rinse bonding agents

Supported, in part, by grants: FIRB RBAP1095CR and PRIN 2009SAN9K5 and 2009FXT3WL from MIUR, Italy.

This abstract is based on research that was funded entirely or partially by an outside source: FIRB RBAP1095CR and PRIN 2009SAN9K5 and 2009FXT3WL from MIUR, Italy

Keywords: Adhesion, Dental materials, Dentin bonding agents and conversion