Microtensile bond strength and microleakage evaluation of two different type of fluoride containing and fluoride free adhesive systems and energy dispersive spectrometry analysis of cavity-restoration interfaces

The aim of this in-vitro study is to compare the microtensile bond strengths of two different fluoride-containing and one fluoride-free adhesive systems and microleakages of Class V cavities prepared by conventional methods and restored with a composite material and to evaluate the cavity-restoration interfaces by SEM for Energy Dispersive Spectrometry (EDS) analyses. 51 premolars without caries and restorations extracted for orthodontic purposes were used. 30 premolars were selected randomly for microtensile test. Class V cavities were prepared on the buccal surface in each teeth with conventional method and cavity dimensions were 4 mm mesio-distal width, 3 mm bucco-lingual height and the depth of the cavities were 2 mm. The prepared teeth were then divided into 3 groups and restored with 3 different adhesive systems (AdheSE One F, Clearfil SE Bond and FL Bond II) according to the manufacturer's instructions and restorations were completed with the resin composite Filtek Z250 (A2). The specimens were stored for 24 hours. Then they were termocycled for 1000 cycles between 5 oC and 55 oC. The microtensile test was performed in an universal testing machine. 12 premolar teeth chosen randomly for microleakage test and Class V cavities were prepared with conventional method on the buccal and the lingual/palatal surfaces, with the same dimension as in the microtensile study. The prepared teeth were then divided into 3 groups and restored with 3 different adhesive systems (AdheSE One F, Clearfil SE Bond and FL Bond II) according to the manufacturer's instructions and restorations were completed with the resin composite Filtek Z250 (A2). The specimens were stored for 24 hours. Then they were termocycled for 1000 cycles between 5 oC and 55 oC. After thermocycling procedure, the root apical of each teeth were closed with composite restoration. Then two layers of a dark colored nail polish was applied onto the teeth 1.5 mm close to cavity margins. All specimens were immersed in %0.5 basic fuchsin for 24 hours. All teeth were sectioned in a mesio-distal direction to seperate the cavities and 24 specimens were obtained. Then the cavities were sectioned in a bucco-lingual direction through the center of both cavities and examined with steromicroscope. 9 premolars were selected for EDS analysis. Class V cavities were prepared on the buccal surface in each teeth with conventional method. The prepared teeth then were divided into 3 groups and restored with 3 different adhesive systems (AdheSE One F, Clearfil SE Bond and FL Bond II) according to the manufacturer's instructions and restorations were completed with the resin composite Filtek Z250 (A2). Restorations were stored in distilled water (replaced every 48 hour) 37 0C dessicator for 30 days. Then the specimens were cross-sectioned longitudionally through the center of the restorations and then embedded in acrylic resin. After the polishing procedures, the samples were sputter-coated with gold, and dentin-adhesive interfaces were observed under a SEM for EDS analysis. Bond strength was analysed statistically by 'Oneway ANOVA' and 'Tukey HSD' tests. The microleakage results were analysed with 'Freeman Halton test', 'Ki-square test' and 'Exact Ki-square' tests. In conclusion, statistically, the cavities prepared with FL Bond II adhesive system showed significantly lower bond strengths than the cavities prepared with Clearfil SE Bond and AdheSE One F. There was no statistical difference between cavities restored with Clearfil SE Bond and AdheSE One F. There was no statistical difference for microleakage results between all the groups and no statistical difference was found for the groups of occlusal and gingival margines. In SEM evaluation for EDS analysis, there was no fluoride ions observed in the adhesive layer and the dentine with the groups restored with Clearfil SE Bond and AdheSE One F. Fluoride ions were observed in the adhesive layer restored with FL Bond II group, but in the dentine tissue no fluoride ion was observed.