Evaluation of composite resin bonding properties with self etch dentin adhesive system in the presence of different properties of base materials

The placement of base and liners under dental restorations has been one of the routine procedures of restorative dentistry over the years. The most important purpose of these materials is to protect the pulp against the damage to the restorative material (residual monomer, polymerization shrink etc.) as well as against microleakage. In addition, the base materials can be used to reduce the amount of composite resin, to support the enamel texture, and to prevent heat and electrical conduction. The purpose of this study was to investigate the effect of different base materials on bond strength of composite resin to dentin and on microleakage of class V restorations. Four different base materials (Ionoseal® / VOCO, TheraCal LC® / Bisco Inc., Ultra-Blend® plus / Ultradent, Vitrebond ™ / 3M-ESPE) self etch adesiv system (CLEARFIL™ SE BOND / Kuraray) and composite resin (Filtek ™ Z250 / 3M) were used in this study. In this study for microleakage; 50 extracted non- cavitated human molar teeth were used. Class V cavities were prepared on the buccal surfaces in 4 mm mesio-distal, 3 mm gingivo-occlusal width and 3 mm depth. The teeth were randomly divided into five groups (n=10). Materials in the experimental groups were placed in 1 mm thickness as liner. Then, a microhybrid composite resin (Filtek ™ Z250) was placed and restorations were completed. In the control group, no base material was applied. After finishing and polishing procedures, thermocycling was performed 5000 times between 5-55 °C. Microleakage of restorations was evaluated by using dye penetration method (basic fuchsin). Results were analyzed by Kruskal Wallis with Bonferroni correction. In this study for shear bond strenght; 50 non-carious extracted human third molar were used in. After the teeth were sectioned mesio-distal to expose dentin surface, specimens were randomly divided into five groups (n=20) to apply different liner or base materials. Liner or base materials were placed on dentin surface according to manufacturer's instructions. Then adhesive system (Clearfil SE Bond, Kuraray Medical Inc., Osaka, Japan) and composite resin (Filtek ™ Z250 / 3M) were applied on materials and dentin. The prepared specimen were placed in a universal testing machine for shear bond strength test. Then, shear bond strength test was performed at a crosshead speed of 1.0 mm/min. Data were analyzed by using One-Way Variance analysis (ANOVA) and Tukey HSD tests. The level of statistical significance was accepted p=0.05. Occlusal (p=0,260) and gingival (p=0,078) microleakage, no statistically significant difference was found between the groups. No significant difference was found between the occlusal and gingival sides of the restorations in any of the test group (p>0.05). While the control group showed higher bond strength, TheraCal LC group showed lower bond strength than the other groups. When comparing the mean shear bond strength, there are statistically significant differences between group Vitrebond and other base materials (p<0.05). Moreover, there are no statistically significant differences between Ionoseal and UltraBlend-plus groups (p<0.05). As a result, it can be said that the use of base material in class V cavities can not prevent microleakage and they reduces the bond strength of composite resin to dentin.