Effect of Surface Treatments and Different Adhesives on the Hybrid Layer Thickness of Non-carious Cervical Lesions

Abstract

SUMMARYThis in vitro study observed and compared the resin and non-carious sclerotic dentin interfaces generated by three different adhesives and two different techniques, using a scanning electron microscope (SEM). Thirty-two human premolars, with buccal, non-carious cervical lesions, were used. The teeth were randomly divided into eight groups. Group 1: Sclerotic dentin was treated with Single Bond (3M). Group 2: After superficial sclerotic dentin was removed with a diamond bur (Diatech, Coltene), the dentin surfaces were treated with Single Bond. Group 3: Sclerotic dentin was treated with Clearfil SE Bond (Kuraray). Group 4: After superficial sclerotic dentin was removed with a diamond bur, Clearfil SE Bond was applied. Group 5: Sclerotic dentin was treated with Xeno III (Dentsply). Group 6: After superficial sclerotic dentin was removed with a bur, Xeno III was applied to the dentin surfaces. For Groups 7 and 8, after the superficial sclerotic dentin was removed with a diamond bur, Clearfil SE Bond, with an additional 37% phosphoric acid gel, was used on the sclerotic dentin surfaces in Group 7 and Xeno III was used in Group 8. In all groups, the cavities were restored with Filtek Supreme (3M). All the specimens were sectioned longitudinally and polished along the cut surface. The sections were treated with 37% orthophosphoric acid for five seconds, rinsed with water and treated with 5% NaOCL for 10 minutes. The specimens were then gold-sputter coated and evaluated under SEM. The thick- Clinical RelevanceThe quality of the hybrid layer created in non-carious cervical sclerotic lesions may determine the longevity of cervical composite restorations. 339 ness of the hybrid layer was measured on the gingival, occlusal and axial dentin interfaces. ANOVA was performed to determine whether there were any statistically significant differences in hybrid layer thickness. Post-hoc multiple comparisons were done with Tukey's test. Hybrid layer thickness was increased with all adhesives when superficial dentin was removed with a bur. Hybrid layer thickness showed significant differences between total-etch and selfetch systems.

Effect of air abrasion and thermocycling on resin adaptation and shear bond strength to dentin for an etch-and-rinse and self-etch resin adhesive

“…A thinner smear layer remains following air abrasion 19) and while air abrasion does not eliminate the need for etching, the resulting thinner smear layer may be easily penetrated by acid [20][21][22][23] . Reducing the thickness of the smear layer may encourage hybrid layer and resin tag formation for self-etch adhesives 24) which are reported to show a thinner hybrid layer structure 25) . In addition, the clinical performance of the self-etch adhesive systems may be improved following air abrasion by superior micromechanical intermeshing of resin monomers with etched dentin and enhanced resin tag formation, both of which contribute to sealing the pulp, reducing microleakage and minimizing the effects of polymerization shrinkage 26) .…”

Morphological Characteristics of Self-Etch Adhesives Bonding to Non-Carious Cervical Sclerotic Dentin

“…Xeno III is regarded as a moderate self-etch adhesive with a pH value of 1.4. 22) With respect to the acidity of self-etch adhesives, Xeno III showed longer tags and thicker hybrid layer in the interface between resin and normal dentin, whereas short tags and thin hybrid layer were measured from Clearfil SE Bond and G-Bond Plus. The results of statistical analysis also confirmed that there was significant difference in thickness of hybrid layer and length of resin tags for three selfetch adhesives bonded to artificial lesions (Table 2 and Table 3).…”

“…The direction of the tubules directly affects the demineralization of superficial dentin 22) . The perpendicular orientation of the dentinal tubules is associated with longer resin tags 27) .…”

The survival of Class V restorations in general dental practice. Part 2, early failure

“…This is in accord with the views of others who recommend providing some mechanical retention for composite restorations 22 and that roughening the surface is advisable to remove superficial sclerotic dentine to which current composite bonding methods are less effective. 16,23 When placing glass ionomer, preparation of the cavity margins is also necessary to allow adequate bulk for this brittle material. 24 Despite the ability of some materials to adhere to tooth tissue, it would appear advisable in practice to use a bur to prepare these lesions in some way, whichever material is selected.…”