Depth of cure of prosthetic composite materials polymerized with laboratory and handheld photo-curing units

This study examined depth of cure of two prosthetic composite materials (Ar tglass(R) and Dentacolor(R)) polymerized by means of four photocuring units for the purpose of comparing the curing performance of laboratory and hand held curing units. Each composite material was photo-exposed either with on e of two laboratory photo-curing units (Dentacolor XS(R) and UniXS(R)) or w ith one of two handheld photo-curing units (Translux CL(R) and Translux EC( R)). The light sources were differently shaped xenon stroboscopic lamps for the laboratory units, and halogen lamps of differing intensity for the han dheld units. Exposure periods were 20, 30, 60, and 90 s, and depth of cure of the materials was determined with a scraping technique. The two handheld curing units generated significantly greater depth of cure for both materi als than either of the two laboratory curing units. Of the two laboratory u nits, the Dentacolor XS(R) unit produced somewhat greater depth of cure for all combinations than the UniXS(R) unit, whereas the differences in depth of cure of the two materials exposed with the two handheld units were not s ignificant when the exposure time period was 60 s or more. The Dentacolor(R ) composite generally demonstrated greater depth of cure than the Artglass( R) composite under identical curing conditions.