Determination and Correlation of Depth of Cure of a New Composite Resin Delivery System.

OBJECTIVES: To quantify the depth of cure (DOC) of a composite resin system using two different testing criteria.

METHOD AND MATERIALS: The DOC testing employed two different experimental protocol: 1) Forty-eight previously extracted human molars were randomly assigned to four groups of twelve each (n = 12): Group 1 SonicFill composite resin system, shade A1; Group 2 SonicFill, shade A3; Group 3 Herculite Ultra composite resin, shade A1; Group 4 Herculite Ultra, shade A3. Cylindrical cavities (4.0 mm diameter and 10 mm depth) were prepared at the tooth CEJ, in a mesiodistal direction. The preparations were filled with each composite resin material in one bulk increment and polymerized with a LED light for 20 seconds. After 5 minutes, the occlusal surfaces of the teeth (specimens) were ground flat until the composite was exposed in a transverse plane. The uncured (soft) composite was scraped away, using a "modified" ISO 4049 DOC specification, and the remaining cured (hard) material was measured. Three measurements, at different positions of the specimen, were performed, for a total of thirty-six measurements per specimen group. The measurements were averaged and divided by fifty percent, arriving at the final DOC for each specimen. 2) A DOC testing protocol was performed using a two-piece (4.0 mm x 10.0 mm) custom-made Teflon device (mold). The groupings duplicated the previous experimental protocol. The mold was filled with each composite resin material in one bulk increment to a 10 mm length (depth). Excess composite material was removed, followed by placement of a Mylar strip over the external orifice. The composite resin specimen was light-polymerized for 20 seconds. Again, the uncured (soft) composite was scraped away, with the same measurement protocol followed as in method 1. Statistical analyses were conducted using ANOVA tests at a p < .05 level of significance.

RESULTS: Statistical differences were exhibited between the two different DOC methodologies, extracted teeth versus the Teflon device. Considering each method, the SonicFilTM composite revealed significantly greater DOC compared to the Herculite Ultra composite resin. Also, significant differences were displayed between the Al compared to the A3 shades, with the A1 (lighter) shades exhibiting greater DOC.

CONCLUSION: The prepped teeth seemed a more realistic DOC testing approach due to the variables of light interaction of the composite resin to either tooth substance (enamel/dentin) versus using the Tefion mold, although greater DOCs were recorded using the manufactured device. The SonicFill composite system did reveal greater DOC compared to the Herculite Ultra composite regardless of experimental method or material shade.