Effect of curing with a plasma light on the properties of polymerizable dental restorative materials

Specimens of light-curable dental restoratives have been prepared using eit her a conventional dental curing lamp (for 20 or 30 s) or a plasma light (f or 1 or 2 s). The specimens were then stored in water until their mass equi librated, then dried to constant mass. Most specimens lost material in this process but the losses in all specimens cured with the plasma light were s ignificantly greater than those cured with the conventional lights (P < 0.0 5). Longer cure times gave slightly reduced losses in water in most cases. The specimens were then returned to water and allowed to re-equilibrate and their equilibrium water uptake determined. There was no simple trend in th is latter property because elution of loosely bound hydrophilic species may have resulted in a less hydrophilic specimen, whose equilbrium water conte nt was therefore correspondingly lower. Overall, the losses through dissolu tion in water suggest that plasma curing is less effective for these materi als than conventional light curing, as it probably results in material with lower molar mass. The losses for the resin-modified glass-ionomer were muc h greater than for other materials, and it was concluded that the more rapi d polymerization with plasma light caused a significant inhibitation of the acid-base part of the setting process. These findings suggest that long-te rm durability of materials may be compromised by employing plasma light cur e rather than a conventional cure system and further studies of this point are recommended.