EVALUATION OF CURING UNITS USED IN PRIVATE DENTAL OFFICES

It is well known that numerous factors influence the light output of c uring units, but many dentists are unaware that the output of their cu ring lights are inadequate. This study was conducted to evaluate the l ight intensity of visible-light curing units in private dental offices and to assess their curing efficiency by measuring compressive streng th of a light-cured resin. Also, in order to determine the maximum lig ht intensity of the units, lamps, filters, and fiber optic a ere repla ced by new ones and curing efficiency remeasured. Light intensity was measured by employing a Quantum Radiometer LI-189 at a wavelength of 4 70+/-40 nm using a bandpass filter. Compressive strength of a light-cu red resin using the light units was measured employing an Instron Test ing Machine at a crosshead speed of 1.0 mm/min. From the evaluation of 105 light units,the light intensity ranged from 28 to 1368 W/m(2) (0 similar to 500 W/m(2); 41.9%, 500 similar to 1000 W/ 2; 45.7%, 1000 si milar to 1500 W/m(2); 12.4%). Light intensity of the light unit in pri vate offices decreased 15.9 similar to 82.1% compared to brand-new uni ts. Reduction of light intensity impaired compressive strength of the light-cured resin to varying degrees (148.3 similar to 279.9 MPa) comp ared with the highest value (317 MPa) obtained from brand-new light un its. The replacement of the Darts increased the light intensity,with m aximum increases of 36.0% for lamps, 157.7% for filters, 46.2% for fib er optics, and 322.7% for all three parts. The results of this study i ndicated that the light intensities of the curing units used in privat e practice were lower than expected.