The Journal of Contemporary Dental Practice

Register      Login

SEARCH WITHIN CONTENT

FIND ARTICLE

Volume / Issue

Online First

Archive
Volume  25 (2024)
Volume  24 (2023)
Volume  23 (2022)
Volume  22 (2021)
Volume  21 (2020)
Volume  20 (2019)
Volume  19 (2018)
Volume  18 (2017)
Volume  17 (2016)
Volume  16 (2015)
Volume  15 (2014)
Volume  14 (2013)
Volume  13 (2012)
Volume  12 (2011)
Volume  11 (2010)
Volume  10 (2009)
Volume  9 (2008)
Volume  8 (2007)
Volume  7 (2006)
Volume  6 (2005)
Volume  5 (2004)
Volume  4 (2003)
Volume  3 (2002)
Volume  2 (2001)
Volume  1 (1999)
Related articles

VOLUME 10 , ISSUE 2 ( March, 2009 ) > List of Articles

RESEARCH ARTICLE

Influence of Different Exposure Times Required to Stabilize Hardness Values of Composite Resin Restorations

Larissa Maria Cavalcante, Luiz André Freire Pimenta, Nick Silikas, Thiago Assunção Valentino, Bruno Carlini-Jr.

Citation Information : Cavalcante LM, Pimenta LA, Silikas N, Valentino TA, Carlini-Jr. B. Influence of Different Exposure Times Required to Stabilize Hardness Values of Composite Resin Restorations. J Contemp Dent Pract 2009; 10 (2):42-50.

DOI: 10.5005/jcdp-10-2-42

License: CC BY-NC 3.0

Published Online: 01-08-2011

Copyright Statement:  Copyright © 2009; The Author(s).


Abstract

Aim

The purpose of this study was to evaluate if Knoop hardness values (KHN) for top and bottom surfaces of resin composite materials can reach a plateau within a clinically acceptable photoactivation time.

Methods and Materials

Four light-curing units (LCUs) were evaluated in this study (n=5): QTH (Optilux501: 550 mW/cm2) and LEDs (FreeLight2: 1100 mW/cm2; UltraLume5: 900 mW/cm2; and Radii: 750 mW/cm2). Composite resin discs (4 mm × 2 mm) of Heliomolar (Ivoclar/Vivadent) and Herculite XRV (Kerr) were tested using five photoactivation times (20, 40, 60, 80, and 100 seconds). KHN were obtained for each test specimen and comparisons between LCUs, depths, and photoactivation times were analyzed using two-way analysis of variance (ANOVA) and polynomial regression analysis.

Results

Data for Heliomolar discs using linear regression found a relationship between the independent variables KHN and time with the Optilux501 at the top and bottom surfaces (r2=0.68/ r2=0.66). Radii presented a linear regression at the top surface (r2=0.75) and a quadratic regression at the bottom (r2=0.94). A quadratic regression was also detected for UltraLume5 and FreeLight2 at both top (r2=0.84/ r2=0.94) and bottom surfaces (r2=0.97/ r2=0.90), respectively, reaching a plateau at 80 seconds in all cases. For Herculite XRV, a quadratic regression was observed for all LCUs at the top and bottom surfaces and 80 seconds irradiation time was needed to reach a plateau in KHN.

Conclusion

There is a specific, but not clinically acceptable, photoactivation time that KHN at both top and bottom surfaces can reach a plateau and is dependent on LCUs and the resin-composite tested.

Clinical Significance

The LCUs and the resin-composite formulation affected the exposure time required to stabilize hardness values. The overall performance of LED LCUs was better than the QTH LCU regardless of the material evaluated.

Citation

Cavalcante LM, Valentino TA, Carlini B Jr, Silikas N, Pimenta LAF. Influence of Different Exposure Times Required to Stabilize Hardness Values of Composite Resin Restorations. J Contemp Dent Pract 2009 March; (10)2:042-050.

PDF Share
  1. A comparison of polymerization by light-emitting diode and halogen-based lightcuring units. J Am Dent Assoc. Mar 2002; 133(3):335-341.
  2. Effectiveness of composite cure associated with different curing modes of LED lights. Oper Dent. Jul-Aug 2003; 28(4):371-377.
  3. Polymerization efficiency of LED curing lights. J Esthet Restor Dent. 2002; 14(5):286-295.
  4. Effect of reduced exposure times on the microhardness of 10 resin composites cured by high-power LED and QTH curing lights. J Can Dent Assoc. Mar 2006; 72(2):147.
  5. Light-emitting diode (LED) polymerisation of dental composites: flexural properties and polymerisation potential. Biomaterials. Jul 2000;21(13):1379-1385.
  6. Effect of light wavelength on polymerization of light-cured resins. Dent Mater J. Jun 1997; 16(1):60-73.
  7. Wear and marginal breakdown of composites with various degrees of cure. J Dent Res. Aug 1997; 76(8):1508-1516.
  8. Influence of photoactivationmethod on conversion, mechanical properties, degradation in ethanol and contraction stress of resin-based materials. J Dent. Oct 2005; 33(9):773-779.
  9. Effect of light intensity and exposure duration on cure of resin composite. Oper Dent. Jan-Feb 1994; 19(1):26-32.
  10. Evaluation of a second-generation LED curing light. J Can Dent Assoc. Nov 2003; 69(10):66.
  11. Microhardness of resin composites polymerized by plasma arc or conventional visible light curing. Oper Dent. Jan-Feb 2002; 27(1):30-37.
  12. Curing performance of a new-generation light-emitting diode dental curing unit. J Am Dent Assoc. Oct 2004; 135(10):1471-1479.
  13. How light irradiance and curing time affect monomer conversion in lightcured resin composites. Eur J Oral Sci. Dec 2003; 111(6):536-542.
  14. Performance of two blue light-emitting-diode dental light curing units with distance and irradiation-time. Dent Mater. Jan 2004; 20(1):72-79.
  15. The effect of cure rate on the mechanical properties of dental resins. Dent Mater. Nov 2001; 17(6):504-511.
  16. Cross-link density evaluation through softening tests: effect of ethanol concentration. Dent Mater. Feb 2008; 24(2):199-203.
  17. Curing-light attenuation in filled-resin restorative materials. Dent Mater. Sep 2006; 22(9):804-817.
  18. The effect of irradiation wavelength bandwidth and spot size on the scraping depth and temperature rise in composite exposed to an argon laser or a conventional quartz-tungsten-halogen source. Dent Mater. May 2002; 18(3):221-226.
  19. Conversion in different depths of ultraviolet and visible light activated composite materials. Acta Odontol Scand. 1982; 40(3):179-192.
  20. Translucency of dental porcelains. J Dent Res. Jan 1980; 59(1):70-75.
PDF Share
PDF Share

© Jaypee Brothers Medical Publishers (P) LTD.