Factors Affecting the Energy Delivered to Simulated Class I and Class V Preparations(10)

clinical practice may not be sufficiently polymerized. Failure to deliver the necessary energy for polymerization of a restoration may contribute to secondary caries, fracture of the restoration and marginal defects, which are the major reasons for failure of resin composite restorations.^44-46

Clinical Implications

This study transfers curing light research from the laboratory environment to a clinical setting and has real-life implications. The results reported here illustrate the significant effects of operator technique, curing light and preparation location on the amount of energy delivered to a restoration.

The MARC device uses a laboratory-grade, NIST-referenced spectroradiometer to measure the irradiance delivered to simulated preparations. As such, the measurements obtained in this study are more accurate than those generated by dental radiometers.^22,23 The observation that insufficient light energy may be delivered to preparations has both research and clinical implications. During laboratory research with a curing light, the unit is typically clamped rigidly directly over the specimen, which minimizes variability in the amount of energy delivered and helps to ensure that the specimens undergo adequate curing, as long as the required energy level is achieved. However, in this study there was much variability among clinical operators using the same curing light (Tables 2 and 3). Also, although many operators delivered less than 10 J/cm², some delivered more. Given the potential for unacceptable temperature increases in the pulp and the oral soft tissues caused by delivering too much energy, as well as the potential for thermal damage to the pulp,^36-40 it is inappropriate to arbitrarily increase exposure times without knowing how much energy is actually being delivered to the restoration.

Limitations

The lights used in this study were all relatively new and well maintained and as such probably delivered a higher irradiance than many of the curing li