Share Bond Test and Water Sorbtion of New Adhesives Systems

Objectives: Over 30 years dental adhesives constitute an important group of materials usually used in current dental practice. In the present, the domain development lead to the elaboration of new dental adhesives with a large utilisation and include all the type of adhesives materials begining with the restorations to a complex treatment of crown and dental bridges aplication. The purpose of the present study was to evaluate water sorption in several experimental resins formulated to be used as dentin and enamel bonding agent and also to determinate the adhesion through shear bond test. Method: We formulated two experimental “total etch” adhesive system A1, A2 and experimental “self-etching” systems A3, A4. All the adhesive systems are based on different type of new carboxylic acid monomers, TEGDMA, HEMA and Bis-GMA. Specimen disks were prepared by dispensing the uncured resin into a mould (20±0.1mm in diameter, 1±0.05mm in thickness). After desiccation, the cured specimens were weighed and then stored in distilled water for evaluation of the water diffusion over a 7-day period. For shear bond testing we used the CF1 composite resin, a Romanian product, in association with our elaborated adhesive systems. CF1 consists of 20wt% organic matrix (BisGMA, TEGDMA) and 80wt% silanized filler represented by hydroxylapatite, SiO2-ZrO2 nanoparticles, quartz and colloidal silica. The samples were tested using a universal testing machine, INSTRONE. Results: The most hydrophilic experimental adhesives (A2) showed the highest water sorption than the least hydrophilic resin (A3). The great variability of the results, as well as the important number of cohesive fractures resulted in the classic shear bond strength tests reflect the interactions at the resin composite-adhesive-dental tissue interface. The values are between 15 and 25 MPa. Conclusions: The obtained results revealed better properties for “total etch” adhesive system from water sorption and shear bond test point of view.