Depth of Cure of Proximal Composite Restorations using a New Perforated Metal Matrix
Nguyen D, Motyka N, Meyers E, et al.
59th Medical Wing San Antonio United States, 2016.
The purpose of this study was to compare the depth of cure of a class 2 preparation filled in bulk with composite and polymerized with tri-sited light curing using a new "micro-windowed" metal matrix compared to techniques using more traditional matrix systems. A divergent proximal box was prepared in an extracted human third molar. The cusp tips were flattened slightly and the preparation was lightly lubricated. A bi-tine ring (V4 Ring, Triodent) and three matrix types were placed: ClearMetal "micro-windowed" metal matrix (Triodent), Composi-Tight 3D Clear matrix (Garrison), and V3 Metal Tab-Matrix (Triodent) (n=10). SonicFill 2 (Kerr) and Herculite Ultra (Kerr) composites were placed in bulk and polymerized with a curing light from the occlusal (20-secs) and from the buccal and lingual (10-secs). The V3 Metal matrix was removed before curing from the proximal following the manufacturers’ recommendations. Two additional groups were created with the V3 Metal matrix that were not removed and only cured from the occlusal, using both SonicFill 2 and Herculite Ultra. The composite specimens were removed from the tooth and stored for 24 hours at 37°C. Knoop hardness was determined at one-mm increments at 0.5, 1, 2, 3, 4 and 5mm from the occlusal surface. Percent bottom/maximum hardness ratios were determined based on maximum hardness measured at 0.5 mm from the occlusal surface for each composite. Data were analyzed with separate two-way ANOVAs and Tukey’s post hoc tests examining the effect of depth and matrix type or depth and curing mode per composite type on hardness ratios. For both SonicFill 2 and Herculite Ultra, significant differences were found based on depth, but not on type of matrix band. The use of the new perforated metal matrix band (ClearMetal) resulted in depth of cure that was not significantly different than the use of metal (that was removed) or transparent matrix bands when using tri-sited light curing. An 80% hardness ratio was obtained at over 5mm for SonicFill 2 and over 4mm for Herculite Ultra with trisited light curing. Tri-sited light curing resulted in significantly greater depth of cure than occlusal curing only.
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