DENTIN PERMEABILITY AND BOND QUALITY AS AFFECTED BY NEW BONDING SYSTEMS

Objectives and methods: The relationship between dentine bonding and t he condition of dentine for four dentine bonding systems (All Bond 2, Clearfil Liner Bond, Scotchbond MP and XR Bond) has been examined. Dif ferent dentine conditions were evaluated and correlated with adhesion values. Dentine permeability was calculated using a hydraulic pressure apparatus working under physiological pulpal pressure (6.9 kPa), whil e remaining dentine thickness (RDT) was measured using pincer calipers . Scanning electron microscopic (SEM) examinations were effected to an alyse dentine morphology. These evaluations were considered as an inde x of the condition of dentine. Shear bond strength tests were used to evaluate adhesion. Dentine samples after the bonding systems applicati on were stored for 24 h under pulpal pressure before bond strength was tested. Results: Scanning electron microscopy examinations indicated that the application of bonding system conditioners caused the removal of smear layer, the demineralization of dentine and the formation of a layer of collapsed collagen fibrils in the intertubular and peritubu lar dentine. Primers were able to infiltrate the collagen fibrils. A l ayer of resin infiltrated/reinforced dentine (the so-called 'hybrid la yer') was observed for All Bond 2, Clearfil Liner Bond and Schotchbond MP. Conclusions: Significant correlations were observed only for XR B ond, which proved very sensitive to RDT and dentine permeability despi te the presence of smear layer. The other three materials did not show any correlation with dentine conditions. By contrast they showed the highest bond values.