Effect of composite shade, increment thickness and curing light on temperature rise during photocuring

Division of Restorative Dentistry, Jordan University of Science & Technology, Irbid, Jordan.
Journal of Dentistry (Impact Factor: 2.75). 04/2007; 35(3):238-45. DOI: 10.1016/j.jdent.2006.07.012
Source: PubMed


To examine the effect of composite shade, increment thickness and curing light characteristics on the temperature rise associated with composite photocuring.
Four shades (C2, A4, B1 and B3), four sample thicknesses (2, 3, 4 and 5 mm) of a hybrid resin composite and two curing units, one with two modes of curing, were investigated. The composite samples were packed in polytetrafluoroethylene (PTFE) moulds and cured for 40 s. Samples cured with the ramp curing mode were irradiated for only 20 s. Temperature rises on the undersurface of the curing resin composite were measured using an infrared scanning system.
Shade C2 produced the highest maximum temperature of all shades (56.7 degrees C). Thinner samples produced greater temperature rises (2mm induced 60.9 degrees C, 5 mm induced 45.7 degrees C). Samples cured with Optilux 501 unit produced greater temperature rises (60.9 degrees C) than those cured with Dentsply unit (56.2 degrees C).
There was a quantifiable amount of heat generated during visible light curing of resin composite. The amount of heat generated was influenced by shade selected, thickness of material and characteristics of the light curing unit.

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    • "RBCs causes both an exothermic polymerization reaction and also a temperature rise from the light energy absorbed during irradiation (Bouillaguet et al. 2005; Al-Qudah et al. 2007; Leprince et al. 2013; Shortall et al. 2013). The heat generated depends on the bulk of material, the irradiance, and the rate at which the RBC polymerizes. "
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    ABSTRACT: For improved interstudy reproducibility, reduced risk of premature failures, and ultimately better patient care, researchers and dentists need to know how to accurately characterize the electromagnetic radiation (light) they are delivering to the resins they are using. The output from a light-curing unit (LCU) is commonly characterized by its irradiance. If this value is measured at the light tip, it describes the radiant exitance from the surface of the light tip, and not the irradiance received by the specimen. The value quoted also reflects only an averaged value over the total measurement area and does not represent the irradiance that the resin specimen is receiving locally or at a different moment in time. Recent evidence has reported that the spectral emission and radiant exitance beam profiles from LCUs can be highly inhomogeneous. This can cause nonuniform temperature changes and uneven photopolymerization within the resin restoration. The spectral radiant power can be very different between different brands of LCUs, and the use of irradiance values derived from dental radiometers to describe the output from an LCU for research purposes is discouraged. Manufacturers should provide more information about the light output from the LCU and the absorption spectrum of their resin-based composite (RBC). Ideally, future assessments and research publications should include the following information about the curing light: 1) radiant power output throughout the exposure cycle and the spectral radiant power as a function of wavelength, 2) analysis of the light beam profile and spectral emission across the light beam, and 3) measurement and reporting of the light the RBC specimen received as well as the output measured at the light tip. © International & American Associations for Dental Research 2015.
    Journal of dental research 07/2015; 94(9). DOI:10.1177/0022034515594786 · 4.14 Impact Factor
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    • "The degree of dentin mineralization [12] and the remaining dentin thickness [12] [13] [14] showed a negative correlation with a temperature rise during polymerization of light-cured composites. Previous studies have evaluated the temperature rise during polymerization of composite resin by using a thermistor [5] [9], thermocouples [6–8, 10, 12, 15], differential scanning calorimetry [16], differential thermal analysis [17] [18], and infrared thermography [11] [14]. However, these studies measured the temperature change only at the bottom surface of composites [5] [6] [9], at the pulpal surface of dentin [7] [10] [12], or at the center of composites [8] [15]. "
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    ABSTRACT: Objective. The aim of this study was to evaluate the temperature change at various sites within the composite and on the pulpal side of dentin during polymerization of two composite increments. Materials and Methods. Class I cavities prepared in third molars were restored in two composite increments (). Temperatures were measured for 110 s using eight thermocouples: bottom center of cavity (BC), top center of 1st increment (MC), top center of 2nd increment (TC), bottom corner of cavity (BE), top corner of 1st increment (ME), top corner of 2nd increment (TE), pulpal side of dentin (PD), and center of curing light guide tip (CL). Results. Maximum temperature values (°C) measured during polymerization of 1st increment were MC (59.8); BC (52.8); ME (51.3); CL (50.7); BE (48.4); and PD (39.8). Maximum temperature values during polymerization of 2nd increment were TC 58.5; TE (52.6); MC (51.7); CL (50.0); ME (48.0); BC (46.7); BE (44.5); and PD (38.8). Conclusion. Temperature at the floor of the cavity was significantly higher during polymerization of 1st increment compared to 2nd increment. Temperature rise was higher at the center than at the corner and at the top surface than at the bottom surface of each increment.
    BioMed Research International 12/2014; 2015(1). DOI:10.1155/2015/923808 · 2.71 Impact Factor
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    • "However, the biggest disadvantage of the composite resin is shrinkage and heat production during polymerization. The temperature rise during visible light curing of composite resin is caused by both the exothermic reaction process and the radiant heat from the light curing unit (LCU).5 Therefore, there are many studies that measured the temperature rise during light curing of composite resin and reported contributing factors. "
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    ABSTRACT: While it is reasonably well known that certain dental procedures increase the temperature of the tooth's surface, of greater interest is their potential damaging effect on the pulp and tooth-supporting tissues. Previous studies have investigated the responses of the pulp, periodontal ligament, and alveolar bone to thermal irritation and the temperature at which thermal damage is initiated. There are also many in vitro studies that have measured the temperature increase of the pulp and tooth-supporting tissues during restorative and endodontic procedures. This review article provides an overview of studies measuring temperature increases in tooth structures during several restorative and endodontic procedures, and proposes clinical guidelines for reducing potential thermal hazards to the pulp and supporting tissues.
    08/2013; 38(3):105-112. DOI:10.5395/rde.2013.38.3.105
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