Vol 21 No. 1

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J Bagh College Dentistry Vol. 21(1), 2009 Depth of cure evaluation….. Table 3: Mean depth of cure in mm and standard deviation of the four different light-activated composites cured with the nine-different curing modes. Depth of cure in mm Curing Mode Tetric Ceram Helio molar Herculite XRV Degufill Mineral Control 2.36 1.75 2.87 (0.01) (0.02) (0.05) 1.95 (0.03) PDI 2.29 1.72 2.86 1.975 (0.04) (0.04) (0.02) (0.03) PDII 2.46 2.85 1.9 (0.04) (0.02) (0.04) 2.01 (0.04) SS 2.39 1.84 2.98 (0.05) (0.06) (0.04) 2.11 (0.05) PCI 2.34 1.83 2.89 (0.03) (0.06) (0.05) 1.98 (0.06) PCII 2.37 1.81 2.89 (0.04) (0.06) (0.05) 2.06 (0.03) PLPC 2.47 1.87 (0.05) (0.04) 3.2 (0.05) 1.95 (0.04) PMPC 2.52 3.25 1.9 (0.03) (0.03) (0.05) 2.08 (0.04) RHCC 2.28 1.77 3.21 (0.03) (0.03) (0.07) 1.9 (0.06) Standard deviation in parentheses. DISCUSSION In this study, although both curing mode and composite type significantly affect depth of cure but Figure 4 demonstrated that, the effect of composite composition on the depth of cure is much more than that of curing mode and this is due to the fact that, the most important factors affecting the polymerization depth are the composition and the physical properties of the composite resins and not the energy density and this finding is in agreement with DeBacker & Dermaut (8) . Herculite XRV light-activated composite exhibited the highest depth of cure values for all the nine curing modes (Figure 2) followed by Tetric Ceram, Degufill Mineral, and Heliomolar, which exhibited the lowest depth of cure values. Depth of cure of light activated resin-based composites is a function of the material’s filler composition and resin chemistry, its shade and translucency, the intensity of the light source, and the length of the radiation exposure (9) . The data of this study indicated that, microhybrid resin-based composite had the greatest depth of cure because of their high filler loading (79% by weight) and relatively large Depth of cure in mm 3.5 3 2.5 2 1.5 Tetric Heliomolar Herculite Degufill Composite type Control PDI PDII SS PCI PCII PLPC PMPC RHCC Figure 2: Mean depth of cure in mm of the four different light-activated composites cured with the nine-different curing modes according to the composite type. Table 4: LSD-test of the depth of cure according to the composite type. TetricTetric Tetric Helio Helio molar molar Herculite Helio HerculiteDegufillHerculite Degufill Degufill molar C *** *** *** *** *** *** PDI *** *** *** *** *** *** PDII *** *** *** *** *** *** SS *** *** *** *** *** *** PCI *** *** *** *** *** *** PCII *** *** *** *** *** *** PLPC*** *** *** *** ** *** PMPC*** *** *** *** *** *** RHCC*** *** *** *** *** *** ** : Highly significant difference *** : Very highly significant difference average particle size (0.6-0.7 micron) while for the microfills (66.7% by weight) for the filler loading and (0.04 micron) for the average particle size and in this study, Herculite XRV and Tetric Ceram composites are micro-hybrids and both of them exhibited high depth of cure values in comparison with Heliomolar composite which is a microfilled composite and this finding is in agreement with the findings of Jain & Pershing (10) . The findings of this study, is not in agreement with the findings of Jain & Pershing (10) in that, greater irradiance (energy density) or longer exposure times are needed to cure small particle resin-based composites in an attempt to increase their depth of cure because in this study, the experimental curing modes of high energy density did not greatly increase the depth of cure especially with Heliomolar microfilled lightactivated composite (Figure 2). Restorative Dentistry 7
J Bagh College Dentistry Vol. 21(1), 2009 Depth of cure evaluation….. REFERENCES 1. Myers ML, Caughman WF, Rueggeberg FA. Effect of restoration composition, shade, and thickness on the cure of a photoactivated resin cement. J Prosthodont 1994; 3:149-57. 2. Cook WD, Standish PM. Cure of resin based restorative materials, II: white light photopolymerized resins. Aust Dent J 1983; 28: 307-11. 3. International Organization for Standardization: ISO 4049:2000: Dentistry-polymer-based filling, restorative and luting materials. 3 rd ed. Geneva, Switzerland: International Organization for Standardization; 2000. 4. Morrow L, Wilson NH, Setcos JC. Single-use, disposable, presterilized light activation probe: the future? Quintessence Int 1998; 29(12): 781-5. 5. Manhart J, Chen HY, Hickel R. The suitability of packable resin-based composites for posterior restorations. J Am Dent Assoc 2001: 132(5): 639-45. 6. Yap AUJ, Soh MS, Siow KS. Effectiveness of composite cure with pulse activation and soft-start polymerization. Oper Dent 2002; 27:44-9. 7. Al-Shekhli AA, Al- Azzawi HJ, Al-Aubi IA. Effctiveness of four different light-activated composites cure with different light energy densities. Mustansiria Dental Journal 2006; 3(3):224-9. 8. DeBacker J, Dermaut L. Visible light sources and posterior visible light cured resins: a particle mixture. Quintessence Int 1986; 17: 635-41. 9. Rueggeberg FA, Caughman WF, Curtis JW & Davis HC. A predictive model for the polymerization of photo-activated resin composites. Int J Prosthodont 1994; 7: 159-66. 10. Jain P, Pershing A. Depth of cure and microleakage with high-intensity and ramped resin-based composite curing lights. J Am Dent Assoc 2003; 134 (9): 1215-23. Restorative Dentistry 8
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