Comparative study of surface microhardness of methacrylate-based composite resins polymerized with light-emitting diodes and halogen

ABSTRACT

Objective: The aim of this study was to evaluate the effect of polymerization with quartz-tungsten-halogen (QTH) and light-emitting diodes (LED) on the surface microhardness of eight commercially available light-polymerized, methacrylate-based composite resins, with different filler particle composition (microfill, minifill, nanohybrids, and microhybrids) immediately after polymerization, after 24 hours, and after three months of storage. Materials and Methods: Eighty disk-shaped specimens were prepared using a split Teflon mold (6 × 2 mm) and were irradiated with either the QTH (Elipar 2500; 600 mW/cm ² ) for 20 seconds or an LED (Bluephase G2; 1,200 mW/cm ² ) for 40 seconds. The microhardness values were recorded using a Vickers hardness tester at a 300 g load for 15 seconds, immediately after polymerization, after 24 hours, and after three months of dark aging in distilled water at 37°C. Statistical analysis was performed using a two-way analysis of variance (ANOVA) and the Tukey′s test. Results: The baseline values demonstrated a significant effect of the composite and the interaction composite-LCU on the microhardness (P < 0.05). At 24 hours, only the composite variable showed a significant effect on the hardness values (P < 0.05). After three months, the composite, LCU, and the interaction composite-LCU all demonstrated a significant effect on the microhardness (P < 0.05). Conclusions: The effectiveness of polymerization, measured in terms of surface hardness, was shown to be dependent not only on the type of light curing unit, but also on the type of composite. Moreover, the choice of composite was shown to affect the performance of the light curing unit.

Key words:

Composite resin - halogen - light-emitting diodes - microhardness - polymerization

• REFERENCES

• 1 Tseng WY, Huang CH, Chen RS, Lee MS, Chen YJ, Rueggeberg FA. et al. Monomer conversion and cytotoxicity of dental composites irradiated with different modes of photoactivated curing. J Biomed Mater Res B Appl Biomater 2007; 83: 85-90
• 2 Leonard DL, Charlton DG, Roberts HW, Cohen ME. Polymerization efficiency of LED curing lights. J Esthet Restor Dent 2002; 14: 286-95
• 3 Aravamudhan K, Rakowski D, Fan PL. Variation of depth of cure and intensity with distance using LED curing lights. Dent Mater 2006; 22: 988-94
• 4 Peutzfeldt A. Resin composites in dentistry: The monomer systems. Eur J Oral Sci 1997; 105: 97-116
• 5 Rueggeberg F. Contemporary issues in photocuring. Compend Contin Educ Dent Suppl 1999; S4-15 quiz S73
• 6 Chung KH, Greener EH. Correlation between degree of conversion, filler concentration and mechanical properties of posterior composite resins. J Oral Rehabil 1990; 17: 487-94
• 7 Ferracane JL, Greener EH. The effect of resin formulation on the degree of conversion and mechanical properties of dental restorative resins. J Biomed Mater Res 1986; 20: 121-31
• 8 Eliades GC, Vougiouklakis GJ, Caputo AA. Degree of double bond conversion in light-cured composites. Dent Mater 1987; 3: 19-25
• 9 Halvorson RH, Erickson RL, Davidson CL. Energy dependent polymerization of resin-based composite. Dent Mater 2002; 18: 463-9
• 10 Sideridou I, Tserki V, Papanastasiou G. Effect of chemical structure on degree of conversion in light-cured dimethacrylate-based dental resins. Biomaterials 2002; 23: 1819-29
• 11 Mills RW, Uhl A, Blackwell GB, Jandt KD. High power light emitting diode (LED) arrays versus halogen light polymerization of oral biomaterials: Barcol hardness, compressive strength and radiometric properties. Biomaterials 2002; 23: 2955-63
• 12 Price RB, Felix CA, Andreou P. Knoop hardness of ten resin composites irradiated with high-power LED and quartz-tungsten-halogen lights. Biomaterials 2005; 26: 2631-41
• 13 Uhl A, Sigusch BW, Jandt KD. Second generation LEDs for the polymerization of oral biomaterials. Dent Mater 2004; 20: 80-7
• 14 Ruttermann S, Tomruk S, Raab WH, Janda R. Effect of energy density on the physical properties of resin-based restorative materials when polymerized with quartz-tungsten halogen or LED-light. Eur J Dent 2010; 4: 183-91
• 15 Fleming GJ, Awan M, Cooper PR, Sloan AJ. The potential of a resin-composite to be cured to a 4mm depth. Dent Mater 2008; 24: 522-9
• 16 Ferracane JL. Correlation between hardness and degree of conversion during the setting reaction of unfilled dental restorative resins. Dent Mater 1985; 1: 11-4
• 17 Mills RW, Jandt KD, Ashworth SH. Dental composite depth of cure with halogen and blue light emitting diode technology. Br Dent J 1999; 186: 388-91
• 18 Dietschi D, Campanile G, Holz J, Meyer JM. Comparison of the color stability of ten new-generation composites: An in vitro study. Dent Mater 1994; 10: 353-62
• 19 Doray PG, Wang X, Powers JM, Burgess JO. Accelerated aging affects color stability of provisional restorative materials. J Prosthodont 1997; 6: 183-8
• 20 Santos GB, Medeiros IS, Fellows CE, Muench A, Braga RR. Composite depth of cure obtained with QTH and LED units assessed by microhardness and micro-Raman spectroscopy. Oper Dent 2007; 32: 79-83
• 21 Rode KM, Kawano Y, Turbino ML. Evaluation of curing light distance on resin composite microhardness and polymerization. Oper Dent 2007; 32: 571-8
• 22 da Silva EM, Poskus LT, Guimaraes JG. Influence of light-polymerization modes on the degree of conversion and mechanical properties of resin composites: A comparative analysis between a hybrid and a nanofilled composite. Oper Dent 2008; 33: 287-93
• 23 Uhl A, Michaelis C, Mills RW, Jandt KD. The influence of storage and indenter load on the Knoop hardness of dental composites polymerized with LED and halogen technologies. Dent Mater 2004; 20: 21-8
• 24 Uhl A, Mills RW, Jandt KD. Photoinitiator dependent composite depth of cure and Knoop hardness with halogen and LED light curing units. Biomaterials 2003; 24: 1787-95
• 25 Filipov IA, Vladimirov SB. Residual monomer in a composite resin after light-curing with different sources, light intensities and spectra of radiation. Braz Dent J 2006; 17: 34-8
• 26 Yazici AR, Kugel G, Gul G. The Knoop hardness of a composite resin polymerized with different curing lights and different modes. J Contemp Dent Pract 2007; 8: 52-9
• 27 Hasler C, Zimmerli B, Lussi A. Curing capability of halogen and LED light curing units in deep class II cavities in extracted human molars. Oper Dent 2006; 31: 354-63
• 28 Ye Q, Wang Y, Williams K, Spencer P. Characterization of photopolymerization of dentin adhesives as a function of light source and irradiance. J Biomed Mater Res B Appl Biomater 2007; 80: 440-6
• 29 Campregher UB, Samuel SM, Fortes CB, Medina AD, Collares FM, Ogliari FA. Effectiveness of second-generation light-emitting diode (LED) light curing units. J Contemp Dent Pract 2007; 8: 35-42
• 30 Rueggeberg FA. State-of-the-art: Dental photocuring: A review. Dent Mater 2011; 27: 39-52
• 31 Calheiros FC, Kawano Y, Stansbury JW, Braga RR. Influence of radiant exposure on contraction stress, degree of conversion and mechanical properties of resin composites. Dent Mater 2006; 22: 799-803
• 32 Calheiros FC, Braga RR, Kawano Y, Ballester RY. Relationship between contraction stress and degree of conversion in restorative composites. Dent Mater 2004; 20: 939-46
• 33 Halvorson RH, Erickson RL, Davidson CL. Energy dependent polymerization of resin-based composite. Dent Mater 2002; 18: 463-9
• 34 Roberts HW, Vandewalle KS, Berzins DW, Charlton DG. Accuracy of LED and halogen radiometers using different light sources. J Esthet Restor Dent 2006; 18: 214-22
• 35 Vandewalle KS, Roberts HW, Andrus JL, Dunn WJ. Effect of light dispersion of LED curing lights on resin composite polymerization. J Esthet Restor Dent 2005; 17: 244-54
• 36 Vandewalle KS, Roberts HW, Rueggeberg FA. Power distribution across the face of different light guides and its effect on composite surface microhardness. J Esthet Restor Dent 2008; 20: 108-17
• 37 Pires JA, Cvitko E, Denehy GE, Swift Jr EJ. Effects of curing tip distance on light intensity and composite resin microhardness. Quintessence Int 1993; 24: 517-21
• 38 Sobrinho LC, de Lima AA, Consani S, Sinhoreti MA, Knowles JC. Influence of curing tip distance on composite Knoop hardness values. Braz Dent J 2000; 11: 11-7
• 39 Giorgi MC, Aguiar FH, Soares LE, Martin AA, Liporoni PC, Paulillo LA. Does an additional UV LED improve the degree of conversion and Knoop Hardness of light-shade composite resins?. Eur J Dent 2012; 6: 396-401
• 40 Dunn WJ, Bush AC. A comparison of polymerization by light-emitting diode and halogen-based light-curing units. J Am Dent Assoc 2002; 133: 335-41
• 41 Giorgi MC, Sartini Paulillo LA. Knoop hardness of composites cured with halogen and led light-curing units in class I restorations. Braz J Oral Sci 2009; 8: 30-3
• 42 Leonard DL, Charlton DG, Roberts HR, Hilton TJ, Zionic A. Determination of the minimum irradiance required for adequate polymerization of hybrid and microfill composite. Oper Dent 2001; 26: 176-80
• 43 Malhotra N, Mala K. Light-curing considerations for resin-based composite materials: A review. Part II. Compend Contin Educ Dent 2010; 31: 584-8-590-1 quiz 592, 603
• 44 Sideridou I, Tserki V, Papanastasiou G. Study of water sorption, solubility and modulus of elasticity of light-cured dimethacrylate-based dental resins. Biomaterials 2003; 24: 655-65
• 45 Schneider LF, Cavalcante LM, Prahl SA, Pfeifer CS, Ferracane JL. Curing efficiency of dental resin composites formulated with camphorquinone or trimethylbenzoyl-diphenyl-phosphine oxide. Dent Mater 2012; 28: 392-7
• 46 Santini A, Miletic V, Swift MD, Bradley M. Degree of conversion and microhardness of TPO-containing resin-based composites cured by polywave and monowave LED units. J Dent 2012; 40: 577-84
• 47 Ciccone-Nogueira JC, Borsatto MC, de Souza-Zaron WC, Ramos RP, Palma-Dibb RG. Microhardness of composite resins at different depths varying the post-irradiation time. J Appl Oral Sci 2007; 15: 305-9