Effects of Seven Curing Lights on Microhardness of Five Composites

*1612 Effects of Seven Curing Lights on Microhardness of Five Composites*
R.B. PRICE¹, T.J. FAHEY², C.M. FELIX¹, P. ANDREOU¹, and C.A. FELIX¹, ¹Dalhousie University, Halifax, Canada, ²Statistical Consultant, Halifax, Canada Objectives: This study tested the effect of curing five composites with seven lights at clinically relevant distances of 4 and 8mm to determine which light produced the hardest composite. Methods: A recent survey showed that 55% of dentists use their curing lights for shorter than the composite manufacturers' recommended times. Therefore, the lights were used for clinically relevant times of 5 or 10 seconds and compared with a QTH light used for 20s. Three examples of each brand of light were used for: Sapphire (5s cure), BluePhase16i (5s cure), LEDemetron II (5s cure), SmartLite IQ (10s cure), UltraLume-5 (10s cure), Allegro (10s cure), Optilux 501 (20s cure). Five composites were used, all shade A2: Vit-l-escence, Tetric Evoceram, Z250, Solitaire, Four Seasons. The Knoop microhardness was measured at 49 points across the top and bottom of 2mm thick composite specimens 24 hours after irradiation and the surface hardness was plotted. Analyses were completed using SAS PROC MIXED (for initial mixed model) followed by PROC GLM for the final model, using an alpha of 0.01. Results: Multiple comparison tests were done to rank the seven lights. Significant effects for the effect of light, composite, side and distance, and all interactions, were detectable. Z250 produced the hardest surfaces; Vit-l-essence was second hardest at 16.8KHN lower than Z250. Solitaire 2 produced the lowest average hardness of all composites (17.1KHN less than Vit-l-escence). The Sapphire plasma arc light produced hardness values that were at least 4.7KHN higher than all other lights and up to 18.1KHN harder than the worst light tested. Comparing overall composite hardness, the lights were ranked from best to worst (p<0.01) Sapphire, Optilux 501 (20s cure), Allegro, UltraLume-5, Smartlite IQ, LEDemetron II, Bluephase16i. Conclusion: For these 5 composites, the high power Sapphire light used for 5s produced the hardest composites (p<0.01).
Seq #186 - Mechanical Properties 3 2:00 PM-3:15 PM, Friday, March 23, 2007 Ernest N. Morial Convention Center Exhibit Hall I2-J
Back to the Dental Materials: VI - Polymer Materials-Mechanical Properties and Degradation Program Back to the IADR/AADR/CADR 85th General Session and Exhibition (March 21-24, 2007)
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