Depth-of-Cure of Proximal Composite Restorations using a Perforated Metal Matrix

Objectives: To compare the depth-of-cure of a new “micro-windowed” metal matrix to more traditional matrix systems in a Class 2 preparation filled in bulk with composite and polymerized with tri-sited light curing.
Methods: A divergent proximal box was prepared in an extracted human third molar measuring 5.6mm (occluso-gingival) X 5.2mm (bucco-lingual) X 2.5mm (axial). The prepared tooth was mounted next to a module tooth (ModuPro, Acadental). The cusps tips were flattened slightly and the preparation was lightly lubricated. SonicFill 2 (Kerr) and Herculite Ultra (Kerr) composites were placed using a bi-tine ring (V4 Ring, Triodent) and three matrix types: ClearMetal matrix (Triodent), Composi-Tight 3D Clear matrix (Garrison), and V3 Metal Tab-Matrix (Triodent) (n=10). The composites were polymerized (Bluephase G2, Ivoclar) from the occlusal (20-secs) and from the buccal and lingual (10-secs). The V3 Metal matrix was removed before curing from the proximal. The specimens were stored for 24 hours at 37°C. The intaglio and cameo surfaces were flattened and polished. Knoop hardness (Leco) was determined at one-mm increments starting from the occlusal surface, with the top surface at the depth of 0.5 mm. Percent hardness ratios were determined based on maximum hardness at 0.5 mm. Data were analyzed with an ANOVA/Tukey’s examining the effects of depth or matrix type on hardness ratios per composite (alpha=0.05).
Results: For both SonicFill 2 and Herculite Ultra, significant differences were found based on depth, but not on type of band.
Conclusions: 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 clear matrix bands when using tri-sited light curing. SonicFill 2 had significantly greater depth-of-cure than Herculite Ultra. The 80% hardness ratio was obtained at over 5mm for SonicFill 2 and over 4mm for Herculite with tri-sited light curing.