The potential of a resin-composite to be cured to a 4 mm depth

Objectives The potential of a recently marketed resin-based composite (RBC), namely X-tra fil (shade A3), which claims to be amenable to curing to a depth of 4 mm was investigated. Methods Disc-shaped specimens (11 mm diameter, 2 mm thickness) of Filtek™ Z250, Admira and X-tra fil were tested in bi-axial flexure to determine the strength. Water sorption, water solubility and Vickers hardness measurements were determined following short-term (0.1, 0.5, 1, 4, 24 and 48 h) and medium-term (1, 4, 12 and 26 weeks) water immersion on disc-shaped specimens (11 mm diameter, 1 mm thickness). The top (t) 0–1 mm depth and bottom (b) 3–4 mm depth of X-tra fil were tested for water sorption, water solubility and Vickers hardness measurements. In addition an analysis of pulpal cell cytotoxicity at 1, 2, 3, 7 and 14 days was also performed on the RBCs. Results No significant differences in the bi-axial flexure strength or top to bottom hardness ratios were evident between the materials examined. However, the water sorption and water solubility values obtained for Filtek™ Z250 (12.3 ± 1.8 and 2.7 ± 1.6 μg/mm3, respectively) and Admira (16.0 ± 1.5 and 4.3 ± 0.2 μg/mm3, respectively) were increased compared with X-tra fil (t) (5.4 ± 0.7 and 0.8 ± 0.2 μg/mm3, respectively) and X-tra fil (b) (6.8 ± 0.6 and 2.4 ± 1.1 μg/mm3, respectively) but within the ISO specification standard of ≤40 and ≤7.5 μg/mm3, respectively. No statistically significant differences were identified on cell viability between the RBCs used in the current study. Significance The manufacturer claims that the recently marketed material X-tra fil could be cured to a depth of 4 mm appear to be vindicated and the performance in terms of flexure strength, water uptake and biocompatibility are comparable with conventional RBCs.