Effect of Immediate or Delayed Light Activation on Curing Kinetics and Shrinkage Stress of Dual-Cure Resin Cements

Author(s)

Faria-e-Silva, A. ^[1] ; Boaro, L. ^[2] ; Braga, R. ^[2] ; Piva, E. ^[3] ; Arias, V. ^[4] ; Martins, L. ^[5]

Affiliation

^[1] Univ Fed Sergipe, Dept Dent, BR-49060100 Aracaju, SE - Brazil

^[2] Univ Sao Paulo, Dept Dent Mat, Sch Dent, Sao Paulo - Brazil

^[3] Univ Fed Pelotas, Dept Restorat Dent, Sch Dent, Pelotas, RS - Brazil

^[4] Sao Leopoldo Mand Sch Dent, Dept Restorat Dent, Campinas, SP - Brazil

^[5] Univ Estadual Campinas, Dept Restorat Dent, Piracicaba - Brazil

• Document type: Journal article
• Source: Operative Dentistry; v. 36, n. 2, p. 196-204, MAR-APR 2011.
• Web of Science Citations: 22

Abstract

Objectives: This study evaluated the effect of light activation (absence, immediate, or delayed) on conversion kinetics and polymerization stress of three commercial dual-cured resin cements (Enforce, RelyX ARC, and Panavia F). Methods: Degree of conversion (DC) was monitored for 30 minutes using real-time near-Fourier transform infrared spectroscopy. The cement was mixed, placed on the spectrometer sample holder, and light activated either immediately or after five minutes (delayed light activation). When no light activation was performed, the materials were protected from light exposure (control). DC was evaluated at five and 30 minutes postmixture. Maximum rates of polymerization (Rp(max)) were obtained from the first derivative of the DC vs time curve. Polymerization stress was monitored for 30 minutes in 1-mm-thick specimens inserted between two cylinders attached to a universal testing machine. Data were submitted to analysis of variance/Tukey tests (alpha=0.05). Results: Immediate light activation promoted the highest DC at five minutes. At 30 minutes, only RelyX ARC did not present a significant difference in DC between activation modes. Enforce and Panavia F presented higher Rp(max) for immediate and delayed light-activation, respectively. RelyX ARC showed similar Rp(max) for all activation modes. The absence of light activation resulted in the lowest stress followed by delayed light activation, while immediate light activation led to the highest values. RelyX ARC showed higher stress than Enforce, while the stress of Panavia F was similar to that of the others. Conclusion: Delayed light activation reduced the polymerization stress of the resin cements tested without jeopardizing DC. (AU)

• FAPESP's process: 07/01006-1 - Effect of activation mode of dual-cured resin cements on polymerization kinetics, mechanical properties, bond strength and stress generation
• Grantee: André Luís Faria e Silva
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 07/00998-0 - Effect of activation mode of dual-cured resin cements on kinetics of conversion, mechanical properties, bond strenght and stress generation
• Grantee: Luís Roberto Marcondes Martins
• Support Opportunities: Regular Research Grants