A recurring joke in our office is about the blue spots we all see after using a light-curing unit. Some of the time we remember to utilize the orange shield and protect our eyes, others we place the tip of the light curing unit and look away. Today I found out how poor an idea this last one is.There is still a lot we don’t know about light curing efficiency and efficacy, but one thing is for sure. Inadequate curing contributes to premature failure of the restoration. How we hold the tip of the light-curing unit against the tooth is a critical factor we need to understand.
The intensity of the light diminishes in accordance with the distance from the tip. The light also diffuses as it moves laterally from the center of the tip and diminishes in intensity. Curing is dependent on both the intensity of the light and the time of exposure. Often when I look back at the tooth during curing, I have to reposition my assistant’s hand as the curing light has drifted from where she originally positioned it. This movement away from the restorative material has now reduced the effectiveness of the curing cycle. One way to compensate for this is to add time to the curing cycle.
Now that I know this, I will make sure we use our orange protective glasses or shield so we can watch throughout the curing cycle and maintain a steady relationship of the tip to the restoration. If I need to back off due to heat generation when patients are not anesthetized, we will be adding time to compensate.