The effect of applying different treatment protocols on resin composite surfaces exposed to different aging times on bond strength

The aim of this thesis study is to evaluate the effect of different treatment protocols applied to the surfaces of resin composite samples exposed to different aging times on the bond strength in vitro. After placing the microhybrid resin composite (Filtek Z250) in teflon molds with a depth of 4 mm and a diameter of 5 mm, each layer was polymerized with an LED light device and resin composite samples (260 in total) were prepared. The prepared samples were randomly divided into two groups, with 130 in each group. The samples in Group 1 were exposed to accelerated aging test for one month and the samples in Group 2 for twelve months. Subsequently, each group is divided into five subgroups within itself. Group A was determined as the control group and no application was made to the surfaces of the samples (n=10). Only adhesive was applied to the surfaces of Group B samples (n=30). The surfaces of Group C samples were roughened with 320 grit sandpaper under running water (n=30). After the surfaces of Group D samples were roughened with 320 grit sandpaper, they were sandblasted with a CoJet device (n=30). The surfaces of Group E samples were only sandblasted with the CoJet device (n=30). After these procedures, all groups, except the samples in the control group, were divided into three subgroups with 10 samples in each. After applying silane (G-Multi Primer) to the sample surfaces of the first subgroup, silane-free adhesive (Clearfil SE Bond) was applied. Silane-containing adhesive (Single Bond Universal) to the sample surfaces of the second subgroup, and only silane-free adhesive to the third subgroup (Clearfil SE Bond) was applied. The adhesive materials and silane were used in accordance with the manufacturer's instructions. After the adhesive application, a mold with a diameter of 1 mm and a depth of 2 mm was placed on the resin composite samples, the inside of the mold was filled with microhybrid resin composite (Filtek Z250) and polymerized with an LED light device. Subsequently, the bond strength between the resin composite and the resin composite used for repair was measured with the Instron Universal test device by applying force until adhesive interface failure occurred. The type of failure in all samples was evaluated under the light microscope and SEM images of one sample from each group were taken. As a result of the study; there was a difference between the control group and the surface preparation groups in both aged groups (p<0.05). It was determined that the lowest bonding values were obtained in the groups exposed to aging for both one month and twelve months, only in the adhesive group (Group B). It was observed that aging times had different effects on bond strength in all experimental groups. When the effects of adhesive application on bond strength are examined; It was observed that there was no difference between the adhesive applications used in the group exposed to aging for one month, and the adhesive applications had different effects in the group exposed to aging for twelve months. Within the limits of this in vitro study; it was determined that surface roughening contributed significantly to the repair bond strength of the resin composite to the resin composite, and different aging times had different effects on the bond strength. In addition, it was concluded that the use of adhesive increases the bond strength, but the choice of adhesive should be made according to the method used in surface roughening.