Effects of Infection Control Barriers on Light Output from a Dental Light-Curing Unit Used in Various Positions

Light-curing units (LCUs) are often subject to clinician-determined factors such as infection control barriers (ICBs) and different positionings of the light tip that may reduce their radiant exposure. The objective of this study was to investigate the individual and cumulative effects of ICBs and LCU positioning on light output. One LCU was used, in combination with five different ICBs and five different distances and angles. ICBs were also tested when placed correctly to manufacturers’ guidelines, and with creases or seams obstructing the light tip. All variables were tested in isolation and in combination with other variables. Measurements were taken from a laboratory-grade spectrometer, giving values of radiant exposure, irradiance and spectral emission. All ICBs, angles and distances showed significant reductions in light output compared to the control (p < 0.001). With increasing angle and distance, the light output was decreased further, with the greatest reduction of 80.6% from the control seen at 40° and 8 mm with an incorrectly placed ICB. When used with an ICB, an increasing angle also showed a protective relationship on the light output. When ICBs are used or when an increase in distance/angle is unavoidable, clinicians should consider compensating for the loss in radiant exposure by increasing curing times.