Factors Affecting the Energy Delivered to Simulated Class I and Class V Preparations(3)

tion. Consequently, dentists have no way of knowing how much energy they are delivering to restorations. Instead, practitioners must rely on manufacturers' "recommended curing times," which are further qualified according to shade of the resin, thickness of the increment, distance from light source to the resin and light output. The implications of these factors may not always be fully understood.

Undercuring the resin adversely affects its physical properties,^10,21,24-29 reduces bond strength,^10,21,27 increases marginal wear and breakdown,^28,29 decreases biocompatibility,^30-35 potentially increases DNA damage resulting from leachates³² and increases bacterial colonization of the resin.³⁵ Equally undesirable is the delivery of too much energy to the tooth, which may cause thermal damage to the pulp and exposed oral tissues.^36-42 Therefore, it is essential to establish a method for accurately quantifying the energy delivered by a curing light to a dental restoration under clinically relevant conditions. It would then be possible to determine the effects of operator technique, choice of curing light and position of the restoration on the amount of energy that the resin actually receives.

The study reported here provides data to bridge the gap between measurements obtained under ideal laboratory conditions and the clinical situation. The study was undertaken to test 3 research hypotheses. First, given that dental training is highly consistent, it was postulated that there would be no difference between dentists and fourth-year dental students in the ability to deliver a specified amount of energy density. Second, it was hypothesized that the energy density delivered by each curing light would be the same for all operators. Finally, it was assumed that there would be no difference in the energy delivered to Class I and Class V preparations with exposure to the same curing light for the same time.

 

Materials and Methods