ABSTRACT
The aim of this study was to determine the influence of dentinal region on shear bond strength by comparing the shear bond strength between root and coronal dentin when using a nanoionomer material [Ketac N100,3M Espe] and a fifth generation bonding material [Excite,Vivadent] applied with a resin composite [Tetric-ceram,Vivadent]. 40 extracted human incisors were used and sectioned along the cemento-enamel junction to have crown and root parts [20 parts for each material]. Facial surfaces of all parts were flattened to expose dentin. Samples were mounted in plastic rings with acrylic resin. Materials were applied according to the manufacturer instruction by using a Teflon mold. After thermo cycling [500 cycles] shear bond strengths were determined using Instron 1195 Machine at a crosshead speed of 1mm/min. Results were evaluated statistically using T student test [P=0.05]. Statistical study revealed that [Excite+T] showed significantly higher bond strength values with coronal dentin [21.98 Mpa.] than that with root dentin [10.24 Mpa]. Whereas the bond strength values of [KetacN100] with root dentin [12.95 Mpa.] was significantly higher than that with coronal dentin [6.78 Mpa.]. This study reveals to the clear influence of the dentinal region and the type of the restorative material on the shear bond strength to dentin
ABSTRACT
The aim of this in vitro study was to evaluate the microleakage on the gingival margin located below the cemento-enamel junction of class II composite restorations [CR, Tetric-ceram,Vivadent] applied with a 5th generation bonding material [Excite,Vivadent] and to compare it with that seen in open sandwich restorations using a nanoionomer material [OST, Ketac N100,3M] and a composite material [Tetric-ceram]. 48 standardized box-like class II cavities were prepared on 24 noncarious premolars and divided into two groups, each of was restored with one of the two techniques: [CR, Excite +T], [OST, Ketac]. After thermocycling [500 cycles] teeth were immersed in 0.5% methylene blue solution for 24 hours, sectioned mesiodistally and then evaluated for microleakage on gingival wall according to a scale of 4 grades [0-3] using stereomicroscope. Statistical analysis was performed using Mann-Whitney U test [P<0.05]. Results showed significant differences in gingival microleakage between OST, Ketac [grade 3: 91.7%] and CR, Excite +T [grade 3:16.7%]. This study doesn't support the use of KetacNIOO in open sandwich technique applied on class II cavities with gingival margins on root dentin