Comparison of Microhardness and Curing Depth of Two Bulkfill Dentin Materials

Objectives: To evaluate curing depth of a short fiber composite intended for posterior large restorations (everX Posterior,GC,Leuven,Germany) in comparison to other dentin composite (SDR,Dentsply,York,USA).
Methods: Preparation were made in mandibular molars (n=12), according to composites (everX Posterior and SDR). Standard class I cavities were prepared depth of 5mm and self etching bonding system (Clearfill SE bond,Kuraray,Osaka,Japan) was applied to cavities. Two different resin dentin materials were placed to cavities depth of 4mm by bulk technique. Both individually photoactivated for 20s with LED light-curing unit (Elipar Freelight 2, 3M ESPE, St.Paul,MN,USA). A nanohybrite composite (Tetric N-Ceram, Ivoclar Vivadent,Schaan,Liechtenstein) applied 1mm thickness for final restoration and photoactivated again for 20s. After 24h water storage, the teeth were divided into two parts by using hard tissue cutting device. Measurements of microhardness were conducted by using Vickers microhardness indenter and tested across the transversal section of restorations for 0.1,1,2,3 and 4mm.
Results: Statistical analyses of obtained data were evaluated by one way ANOVA and descriptive statistics. Following results were observed: for all tested groups, everX Posterior showed significantly higher microhardness values than SDR (Values of mean for 0.1,1,2,3 and 4 mm were; everX Posterior, 73.2, 72.9, 83.3, 79.8, 79.02 and SDR, 61.3, 60.4, 60.6, 60.6, 62.1) (alldepth for both resin p<0,5). Both everX Posterior and SDR achived great depth of cure over 4mm.
Conclusions: EverX Posterior and SDR exhibited depth of cure over 4mm thickness recommended for bulk placement. Microhardness values are affected by composite material type. Microhardness and polymerization of composites are not influenced by depth.