Kopperud SE, Rukke HV et al. J Dent 2017;58: 67–73

For example, 2% did not use any protection, 8% looked away from the light and 20% used a protection shield mounted on the curing light. A protection shield mounted on a curing light is not sufficient. However, it is not that straightforward in that manufacturers recommend different curing times; these can range from less than 5 seconds to almost 2 minutes. When guidelines are applied to reflected light, the maximum permissible exposure time is 5 min each day. In this study that explored light curing procedures in Norwegian dentists employed in the Public Dentist Service, despite three reminders, only a little over half of those invited answered the questionnaire. The investigators concede their findings must be interpreted in the light of response bias. Apart from the above findings, only about half the respondents checked regularly the irradiance of their units. This would suggest irradiance value indicators incorporated into curing lights are useful.