Curing light dental

curing light dental



The purpose of this study is to examine the intensity of light curing units and factors affecting it in dental offices.

Materials and Methods:

The output intensity of 200 light curing units in dental offices across Maharashtra were examined. The collection of related information (thenumber of months of use of curing unit, the approximate number of times used in a day, and presence or absence of composite build-ups) and measurement of the intensity was performed by two operators. L.E.D Radiometer (Kerr) was used for measuring the output intensity. The average output intensity was divided into three categories (<200 mW/cm 2. 200-400 mW/ cm 2 and >400 mW/cm 2 ).



Keywords: Output intensity, light-emitting diode radiometer, light curing units


Most often, dentists blame the material for the failure of restoration rather than the technique or method of placement of restoration. Most of the studies on composite-resin curing stress the importance of sufficient output intensity of curing lights. Undesirable clinical performance and early failures of composite restorations as a result of inadequate polymerization have been reported.[1 ]This also includes discoloration, water absorption, and decreased hardness. Although issues such as method of placement of composite (bulk vs. incremental) and methods of curing (fast vs. slow) are not fully agreed upon among researchers and clinicians, the value of sufficient output intensity of curing lights to ensure the longevity of restorations and avoid undesirable clinical outcome is universally accepted. The impact of the sufficient intensity out put of curing lights in ensuring the longevity of restorations and avoiding undesirable clinical outcomes is universally accepted.[2 ]

Light-emitting diode (LED) lights have attracted interest and are becoming increasingly popular among dentists in comparison to laser and PAC lights.[3 –6 ]The early generations of LED lights were not capable of providing adequate output (e.g. 350 mW/ cm 2 ). [7 ]Newer generation LED lights produce output in excess of 500 mW/cm 2. These LED lights provide

more consistent outputs than the first-generation units. On average, the LED light source is expected to perform for thousands of hours in comparison to the 30-hour to 50-hour performance of quartz-tungsten-halogen (QTH) bulbs.[8 ] However, this long-term performance should not exempt LED lights from routine in-office evaluation.[8 ] Degradation of bulbs and loss of reflectors caused by heat from the filament, which are commonly seen in QTH lights, does not apply to LED lights that use gallium nitrate semiconductors as the source of luminescence.[9 ]



L.E.D Radiometer (Kerr Manufacturing Products) was used in this study. This L.E.D Radiometer has calibrations for intensity measurement from 0 to 2000 mW/cm 2. It has a detector at the centre and filter placed inside that helps in recording the intensity. The maximum and minimum diameter of detector the is 15 mm and 7 mm respectively; hence, the curing lights with tip diameter ranging from 7 mm or more can be examined by this radiometer.


Two hundred light curing units in dental offices were examined for their output intensity. Collection of related information and measurement of the intensity was performed by two operators. Consent of the dentist was obtained in order to examine the light curing unit in the operatory.

The tip of the unit was cleaned before examination. When a quartz-tungsten-halogen (QTH) unit was examined for the output intensity, the unit was activated for three consecutive 60-s intervals interrupted by 1 s of off time to reduce the cool bulb variable. When a light-emitting diode (LED)unit was examined, three readings were taken, and the average values were obtained. The curing units were divided into two categories: Halogen and LED. The number of years in use, the approximate no of times used in a day were asked and recorded for each curing light. Other information included bulb/ battery replacement frequency, presence or absence of composite build-ups.

The output intensity (mW/cm 2 ) of all the examined lights were categorized into three groups:

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