MICROHARDNESS OF THE APPROXIMAL AND PULPAL SURFACES IN CLASS II COMPOSITE RESTORATIONS: AN IN VITRO STUDY

The aim of this in vitro study was to examine the surface microhardness of composite resin materials when placed in class II cavities using two different matrix systems (Quickmat, Polydentia and Lucifix, HaweNeos). A hybrid composite (Tetric EvoCeram-Ivoclar Vivadent), two nanohybrid composites (Grandio-Voco, Synergy D6-Coltene/Whaledent) and a nanofil composite (Filtek Supreme XT-3M Espe) were placed in the silicon dublicates of class II cavities which were primarly prepared in plastic teeth without levels (4x4x4) mm (n=160). The cavity was prepared in plastic teeth (4mm bucco-lingual x 4 mm depth x 3mm mesio-distal) (KaVo, EWL model). Cavosurface margins were not beveled. The impressions of the tooth with the cavity preparation were taken using polyvinyl siloxan(Speedy/PuttyLigth-Coltene). A silicon material (AffinisPrecious-Coltene) was injected in the impressions and a silicon mold of the teeth and the cavity were obtained. The prepared silicon teeth were mounted in plastic jaw (KaVo, EWL model) to simulate proximal contact. Metal sectional matrix (Quickmat-Polydentia) (n=20) and clear matrix system (Lucifix-HaweNeos) (n=20) were prepared for each tooth. Wedges were used to stabilize the matrix. The cavities were restored incrementally in oblique layers with all four restorative materials. And each increment was light cured for 40 s (Celalux-Voco). The restorations were then removed from the cavities and surface hardness of the proximal and axio-pulpal surfaces were immediatly measured with Microhardness Vickers Test device (Clemex CMT 7, Clemex Labs.). Data were statistically analyzed with one way ANOVA and Tukey's Multiple Comprassion test. No significant differences were found between metal matrix and clear matrix (p>0.05). Microhardness of axio-pulpal surfaces were found significantly lower than the proximal surfaces for each restorative materials (p