How a dentist uses a curing light makes a large difference in the amount of energy a restoration receives. Even when the device is handled correctly, if the energy level is insufficient, then the resulting restoration may not attain expected longevity; this may explain why resin-based restorations last only five to seven years when actual life expectancy should be 15 years or more.

In a collection of articles written for ADA Professional Product Review, Jack L. Ferracane, Professor and Chair, Restorative Dentistry Division Director, Biomaterials and Biomechanics, Oregon Health & Science University in Portland, Oregon states that there is “considerable evidence that delivering inadequate energy to the restoration will result in a restoration that has less than optimal properties and poor clinical performance.”

Other reasons include staining, marginal breakdown, wear, a broken tooth or nerve death. Inadequate delivery of light or energy to the restoration can result in the early breakdown of a light-cured restoration. Therefore, a dental curing light must deliver adequate light energy to attain the best physical, chemical, and optical properties of a resin-based composite restoration.

 Today we have two different kind of dental curing lights, those that are halogen (bulb) lights and those that are LED (light emitting diode). The LED lights do not themselves produce heat, unlike the older bulb lights that come with cooling fans. This unit unlike an LED can get really, and I mean really hot.

This heating effect or non-heating effect of the light unit is however not the most important thermal effect. It is the heat produced by curing of the material, its heat of reaction, that I am focusing on. The light itself however can and does contribute to providing heat to the tooth. A simple test is to put the light tip close your hand and feel how much heat you can detect. Again, the heat build-up by the material overall is the thermal effect that is most important.

Curing lights in use today provide very intense blue light and very short cure times, so even a slight drift reduces the amount of energy delivered to the restoration by a significant percentage. A light-curing device is now commonly found in dental practices across the country. Some assume that a “point and shoot” technique is sufficient. However, in order to achieve optimal results, dental curing lights must be used correctly.