Curing lights--the effects of clinical factors on intensity and polymerisation

Curing lights are used to cure light-sensitive dental materials in clinical situations that range from small, easily accessible restorations to larger ones that are more difficult to access. The degree to which these materials cure depends on the intensity and quality of light to which they are exposed and the curing time. Once the light has left the curing unit, factors such as composite type, composite shade, thickness of resin increment or overlying tooth structure, the distance and orientation of the light tip, and the diameter of the light tip may reduce intensity and provide a lower degree of polymerisation. The only way to overcome this reduction is to increase exposure time. However, surveys have shown that dentists tend to cure for periods that are too short. Reasons for this may be that the dentist is unaware of the importance of adequate light intensity, as well as the influence of all the factors mentioned above that reduce intensity and lower the degree of polymerisation. This paper reviews the clinical factors that may reduce light transmission during polymerisation of composite restorations, and suggests several clinical recommendations to provide general practitioners with information on how to optimise the degree of cure obtained in their surgery.