IN VITRO MICRO SHEAR BOND STRENGTH OF DIFFERENT ADHESIVE SYSTEMS TO SOUND, CARIES AFFECTED AND SCLEROTIC DENTIN

This in-vitro study compared the Micro Shear bond strength of different adhesive systems to prepared specimens of sound, caries affected and sclerotic dentin.
Materials and methods: A total of 90 freshly extracted human molar teeth were collected, 30 prepared for each type of dentin either sound, caries affected or sclerotic dentin. Every type of the prepared dentin groups was subdivided into five subgroups, each receive one of the tested adhesives (n=6). The teeth were embedded vertically in cylindrical Teflon mold of 2 cm height and 20 mm internal diameter using a chemically cured cross-linked acrylic resin, so as to have the full crown projecting above the surface of acrylic resin. Teeth were ground off using model trimmer with low speed and copious water coolant in direction perpendicular to the long axis of the tooth to expose the dentin surface. All the tested adhesive materials were applied on prepared dentin surface (Sound, carious, and sclerotic) together with resin composite material according to manufactures instructions. The prepared specimens were stored immediately in deionized water for 24 hours at 37°C before testing procedures. Micro shear bond strength (µSBS) was tested using the micro shear bond apparatus (DL200 Emic Sao Jose de Pinhas, PR, and Brazil). µSBS MPA= Shear force (N)/cross sectional area (mm2).
Results: ANOVA was used for the effect of type of dentin and adhesive system used. Sound dentin showed the highest µSBS followed by carious dentin and at last came sclerotic dentin. For the adhesive system total etch showed the highest µSBS followed by two step self-etch with etch and rinse and two step self-etch and at last came one step self-etch with etch and rinse and one step self-etch.
Conclusion: Total-etch adhesive revealed higher micro shear bond strength than self-etch adhesive irrespective of the type of dentin tested, in addition, the etch and rinse step improves micro shear bond strength of self-etch adhesive with different type of dentin.