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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    • "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 ( n = 5 ). 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.
    Full-text · Article · Dec 2014 · BioMed Research International
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    • "Previous studies measured the temperature in the lower surface of the composite resin specimens of various thicknesses with electronic infrared thermography while light curing of the upper surface2,3. In this manner, only the temperature of the lower surface could be measured and the temperature within the composite resin could not be measured. "
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    ABSTRACT: The purpose of this study was to investigate the polymerization temperature of a bulk filled composite resin light-activated with various light curing modes using infrared thermography according to the curing depth and approximation to the cavity wall. Composite resin (AeliteFlo, Bisco, Schaumburg, IL, USA) was inserted into a Class II cavity prepared in the Teflon blocks and was cured with a LED light curing unit (Dr's Light, GoodDoctors Co., Seoul, Korea) using various light curing modes for 20 s. Polymerization temperature was measured with an infrared thermographic camera (Thermovision 900 SW/TE, Agema Infra-red Systems AB, Danderyd, Sweden) for 40 s at measurement spots adjacent to the cavity wall and in the middle of the cavity from the surface to a 4 mm depth. Data were analyzed according to the light curing modes with one-way ANOVA, and according to curing depth and approximation to the cavity wall with two-way ANOVA. The peak polymerization temperature of the composite resin was not affected by the light curing modes. According to the curing depth, the peak polymerization temperature at the depth of 1 mm to 3 mm was significantly higher than that at the depth of 4 mm, and on the surface. The peak polymerization temperature of the spots in the middle of the cavity was higher than that measured in spots adjacent to the cavity wall. In the photopolymerization of the composite resin, the temperature was higher in the middle of the cavity compared to the outer surface or at the internal walls of the prepared cavity.
    Full-text · Article · Aug 2013 · Journal of applied oral science: revista FOB
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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.
    Full-text · Article · Aug 2013
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