Intensity of Quartz-Tungsten-Halogen Lights Used in Private Clinics in Egypt

Purpose: the aim of this investigation was to determine light intensity of QTH light curing units used in a sample of dental offices in Cairo. Methods: Dental offices were selected to participate following specific criteria for inclusion. Once enrolled a personnel of the research team visited the office to conduct the survey. A digital light meter (Curite , EFOS) was used for the measurements and was calibrated daily against an analog radiometer (Optilux, model 100, SDS/Kerr) to ensure consistency. At each office surveyed six light intensity measurements were made from each unit following a short warm up period. Age and make of curing unit(s), maintenance history, mode of use with composite as well as availability of a light meter in the office were recorded. Mean light intensity for each curing unit were determined. Results: A total of 113 QTH light curing units found in 100 dental offices were tested. These were made by 32 different manufacturers. Light intensity varied considerably among the offices with mean measurements ranging from 79.2–946.2 mW/cm2 with 41% of the units having mean intensity values of less than 300 mW/cm2. Curing units with intensity of less than 200 mW/cm2 composed 25% of all units while those between 400-499 mW/cm2 were 21%. Most units were from 1 to10 years-old with 20% being more than 10 years-old. Only two of the dental offices visited had a light meter. Dentists used exposure time of approximately 30 sec/increment. These findings are comparable to findings of other international studies. Conclusions: A considerable number of the tested light units emitted light with intensity below critical levels. Dentists in Cairo should be encouraged to periodically examine light intensity of units in their offices and carry out maintenance services as necessary. This is going to ensure optimum quality of composite restorations.