IADR Abstract Archives
Depth of Cure and Cytotoxicity of Bulk-fill Composites
Objectives: To evaluate depth of cure (DOC) and biocompatibility of bulk-fill resin-based composites (RBCs). We hypothesized that bulk-fill RBCs would have better DOC and biocompatibility than the standard RBCs.
Methods: Three bulk-fill RBCs (SDR bulk-fill flowable [SDR], EverX posterior [EXP], Tetric N-Ceram bulk-fill [TNC]) and two standard composites (Filtek Z350 restorative [ZFR] and flowable [ZFF]) were investigated. DOC was validated by measuring surface hardness (KHN; n=5) at the top and 2 / 4-mm depths of block-shaped specimens using a digital microhardness tester (50gf load; 15s dwell time). In vitro biocompatibility was assessed using extraction method based on the ISO 10993. Cured specimens of 2 and 4mm thickness were immersed in cell culture medium and incubated at 37oC for 24h. Extracts were collected and added to pre-seeded L929 mouse fibroblasts for 24h, before assessment of cell viability by MTS assay. Data was analysed using ANOVA and Scheffe’s post hoc testing at a significance level of 0.05.
Results: Mean KHN at the top surface ranged from 39.06 (ZFR) to 24.24 (SDR). For all materials, a decrease in hardness was observed with increased depth (2 versus 4mm). At the top surface, ZFR was significantly harder while SDR was significantly softer than all other materials (p<0.05). At 4mm depth, EXP was significantly harder than TNC and SDR (p<0.05). No KHN readings could be obtained for standard composites at 4mm. Cytotoxicity of standard composites increased when the specimen thickness was increased from 2 to 4mm. At 4mm thickness, undiluted extracts of bulk-fill RBCs (SDR, EXP and TNC) have significant higher cell viability (>60%) than the standard composites (p<0.05).
Conclusions: DOC and biocompatibility of RBCs are product-dependent and generally greater than the standard composites. Among the bulk-fill RBCs, only SDR and EXP demonstrated high cell viability (>70%) at 4mm thickness, supporting the manufacturers' recommendation for curing at 4mm thickness.
Methods: Three bulk-fill RBCs (SDR bulk-fill flowable [SDR], EverX posterior [EXP], Tetric N-Ceram bulk-fill [TNC]) and two standard composites (Filtek Z350 restorative [ZFR] and flowable [ZFF]) were investigated. DOC was validated by measuring surface hardness (KHN; n=5) at the top and 2 / 4-mm depths of block-shaped specimens using a digital microhardness tester (50gf load; 15s dwell time). In vitro biocompatibility was assessed using extraction method based on the ISO 10993. Cured specimens of 2 and 4mm thickness were immersed in cell culture medium and incubated at 37oC for 24h. Extracts were collected and added to pre-seeded L929 mouse fibroblasts for 24h, before assessment of cell viability by MTS assay. Data was analysed using ANOVA and Scheffe’s post hoc testing at a significance level of 0.05.
Results: Mean KHN at the top surface ranged from 39.06 (ZFR) to 24.24 (SDR). For all materials, a decrease in hardness was observed with increased depth (2 versus 4mm). At the top surface, ZFR was significantly harder while SDR was significantly softer than all other materials (p<0.05). At 4mm depth, EXP was significantly harder than TNC and SDR (p<0.05). No KHN readings could be obtained for standard composites at 4mm. Cytotoxicity of standard composites increased when the specimen thickness was increased from 2 to 4mm. At 4mm thickness, undiluted extracts of bulk-fill RBCs (SDR, EXP and TNC) have significant higher cell viability (>60%) than the standard composites (p<0.05).
Conclusions: DOC and biocompatibility of RBCs are product-dependent and generally greater than the standard composites. Among the bulk-fill RBCs, only SDR and EXP demonstrated high cell viability (>70%) at 4mm thickness, supporting the manufacturers' recommendation for curing at 4mm thickness.