A Dynamic Survey Of Power Density Of Clinical Curing-light Units

Light-cured resin composites have met the requirements of the patients and cliniciansfor the tooth cosmetic restoration because of their excellent physical and chemical properties,rich color selectivity and easy to operate. They have been widely used in clinical and havebeen the important materials for the tooth filling treatment. Resin composite can polymerizeand cure under the irradiation of visible light at common temperature. The success of resincomposite restoration depends directly on the degree of polymerizing and curing. As thelight source for curing of resin composite, the performance of curing-light units directlyaffects the whole properties and clinical effect of resin composite.ANSI/ADA regulates, power density of curing light for clinical use is300mW/cm2atleast, in order to ensure the degree of polymerization and curing of the resin composite.When the power density of the curing light is insufficient, it can lead that the polymerizationof resin composite is inadequate and further affect the physical, chemical and biologicalproperties of the materials, such as water absorption and solubility increasing, the lowermechanical strength, poor color stability and more uncured monomers, especially at thebottom of thicker resin layer. These poor performance can cause secondary caries, fracture offilling and even the failure of restoration.However, will the power density of curing light always be kept stable in continuous useeven if the power density of the light curing is above300mW/cm2? The purpose of theresearch is determining whether the power density of clinical curing light is decayed incontinuous use or lack of power by detecting the power density of curing lights at differentstates and different time periods in Stomatology Hospital of Jilin University, in order todetermine whether curing lights can fully cure resin composite and meet the needs of clinicalapplications.The most common types of clinical curing lights are light-emitting diodes (LED) andquartz tungsten halogen(QTH). In this study, the power density of clinical curing lights inStomatology Hospital of Jilin University is detected by a radiometer in following severalways:(1) the power density of curing lights of fully charged and of low power;(2) the powerdensity of curing lights in use after a day;(3) the power density of curing lights in use after alonger period of time (3months, six months). At the same time, the type, the brand, the purchase time, the damage of optical guide and frequency of use are investigated.There are a total of43curing lights, including37LED lights and6QTH lights inStomatology Hospital of Jilin University. The average power density of curing lights is821.6mW/cm2, wherein the average power density of LED is893.4mW/cm2and the averagepower density of QTH is379.2mW/cm2.The power density of Ski curing lights in low powerdecreases significantly (P <0.01), and the power density of other curing lights is not affectedby power. The difference of power density between morning and evening,3months, and6months is not significant. More than80%(35/43) curing light were bought within three yearsand bivariate correlations of power density and light unit age, reveales a significant negativecorrelation (r=-0.591, P <0.001).The mean number used everyday was10.8times. Bivariatecorrelations of power density and light unit frequency reveales no significant negativecorrelation(r=-0.188, P>0.05).A survey of power density of curing lights at different states and different time periods,we can draw the following conclusions:1. The majority of Stomatology Hospital of Jilin University are LED lights, the powerdensity can sufficiently meet the clinical applications and ensure the polymerization and cur-ing of resin composite.2. Curing lights of most brands in Stomatology Hospital of Jilin University have stableperformance, except that power density of Ski curing lights are significantly affected by thepower. The curing lights in low power should be charged in time to ensure the power density.3. It is recommended that clinicians regularly detecting the power density of the curinglights, in order to understand the change of power density.