An Update on Depth of Cure of Bulk-Fill Composite Resins

Objectives: To calculate and compare Depth of Cure (DOC) of bulk-fill composite resins measured by the standard ISO 4049, that utilizes 4mm diameter stainless steel molds, versus 10mm diameter stainless steel molds that match the diameter of curing light allowing full energy delivery to the specimen.
Methods: Paradigm^TM (3M/ESPE) curing light with 10mm diameter tip was used to cure all specimens. Three specimens (n=3) for each of six bulk-fill and the control materials were cured following manufacturer’s directions for use. Immediately after light curing, the specimen was removed from the mold and the soft, unpolymerized composite material was scraped from the bottom of the specimen with a plastic spatula. The length of the apparently cured composite was measured with a digital micrometer and divided by two in accordance with the standard ISO 4049 to calculate the DOC.
Results: Only Venus bulk, Beautifil Bulk Flowable and Z250 met the standard ISO 4049 for DOC. Using the 10mm stainless steel mold, all products tested met the manufacturers claimed DOC except SonicFill2.
Conclusions: Utilizing 10 mm diameter stainless steel molds produced about 25% deeper DOC compared to 4mm diameter across all products tested. This increase matches previous findings using teeth versus standard 4mm molds. Venus Bulk had the highest depth of cure among all composites tested (p<0.01).