| 0510 Intrapulpal Temperature Increases with LED, QTH and Plasma Arc Photoinitiation | ||
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M.R. BOUSCHLICHER, S.R. WHALEN, and D.V. DAWSON, The University of Iowa, Iowa City, USA The near IR and unfiltered IR spectral emission of quartz-tungsten halogen (QTH) and short-arc Xenon or “plasma arc” (PAC) light curing units (LCU) may result in unacceptable intrapulpal temperature increases (5.5°C may elicit a marked intrapulpal response, Zach & Cohen, 1965) during photopolymerization. The narrow spectral emission of blue LED-LCU's (440-490nm) reportedly adds less heat during photopolymerization. Objectives: This study compared intrapulpal temperature increases resulting from photopolymerization of a standardized volume of composite in a Class II preparation using LED-, QTH-, and PAC-LCUs. Methods: A mandibular molar with a conservative Class II preparation was suspended in a 37.0°C water bath. A peristaltic pump perfused the pulp chamber with 37.0°C water (simulated blood flow of 40-50ml/100g of tissue/min.). Intrapulpal and water bath temperatures were recorded with K-type thermocouples and an Omega PC-TC6 thermocouple card and data-logging software. A standardized volume of composite (2 x 3 x 1 mm) representing the first increment was polymerized and temperature change (n=5 per group) was recorded for 180s. Exposure durations utilized were based on equivalent depth of cure. LCU/source/cure modes tested included: Demetron 401 (control)/QTH/40s, Demetron D501 (D501)/QTH/15s ramp, Trilight (TL)/QTH/40s standard, Virtuoso (V)/PAC/9s, FreeLight (FL)/LED/40s. Temperature increases among groups were compared with a Kruskal-Wallace rank ANOVA. Pairwise comparisons were made using a Tukey adjustment (a=0.05). Results: Mean intrapulpal temperature increases °C, (S.D.) and homogeneous subset (means with same subscript letter not significantly different) in descending order were:, control=5.45 (0.54)A, TL=3.73 (0.17)B, V=2.41 (0.23)C, D501=2.01 (0.27)C. FL=1.70 (0.29)C. Conclusions: LED (FL), PAC (V) and newer QTH models (D501, TL) had significantly lower intrapulpal temperature increases than the older QTH control. | ||
| Seq #61 - Properties of Light-curing Units, Polymerization, Radiopacity 11:00 AM-12:15 PM, Thursday, 7 March 2002 San Diego Convention Center Exhibit Hall C | ||
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