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

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 4mm was investigated.

Disc-shaped specimens (11mm diameter, 2mm 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 48h) and medium-term (1, 4, 12 and 26 weeks) water immersion on disc-shaped specimens (11mm diameter, 1mm thickness). The top (t) 0-1mm depth and bottom (b) 3-4mm 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.

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+/-1.6microg/mm3, respectively) and Admira (16.0+/-1.5 and 4.3+/-0.2microg/mm3, respectively) were increased compared with X-tra fil (t) (5.4+/-0.7 and 0.8+/-0.2microg/mm3, respectively) and X-tra fil (b) (6.8+/-0.6 and 2.4+/-1.1microg/mm3, respectively) but within the ISO specification standard of < or =40 and < or =7.5microg/mm(3), respectively. No statistically significant differences were identified on cell viability between the RBCs used in the current study.

The manufacturer claims that the recently marketed material X-tra fil could be cured to a depth of 4mm appear to be vindicated and the performance in terms of flexure strength, water uptake and biocompatibility are comparable with conventional RBCs.