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
This study aimed to investigate curing efficiency of a second generation - light emitting diode [LED] curing unit to polymerise two kinds of resin ,one depends upon camphorquinone as a single photo initiator while the other uses co-initiator besides camphorquinone. 20 specimens 3 mm thick were prepared from 2 composites10 specimens of [Z250, shade A2, 3M/ESPE] and 10 of [TPH3, shade A2, Dentsply]. Specimens were subjected to light polymerisation for 20 seconds using second generation - LED unit [Elipar Free Light 2,3M/ESPE]. Specimens were stored in dark for 24 hours. A hardness tester Galileo Durometria[LTF SPA-Antegnate-Italy] was used to obtain 3 measurements of Vickers hardness number [VHN] for each surface [upper and lower] of each specimen. Hardness ratio [HR] was calculated as the VHN of the lower surface divided by the VHN of upper surface. Data were analyzed with T-student analysis [P