Effect of temperature on post-cure polymerization of bulk-fill composites

• Published in: Journal of dentistry Vol. 42; no. 10; pp. 1255 - 1260
• Main Authors: Par, Matej, Gamulin, Ozren, Marovic, Danijela, Klaric, Eva, Tarle, Zrinka
• Format: Journal Article
• Language: English; Persian
• Published: England Elsevier Ltd 01.10.2014; Elsevier Limited
• Subjects: Composite materials; Composite Resins - chemistry; Conversion; Curing; Degree of conversion; Dental Materials - chemistry; Dentistry; Direct current; Free radicals; Holes; Humans; Light-Curing of Dental Adhesives - methods; Materials Testing; Methacrylate; Methacrylates - chemistry; Physical properties; Polyethylene terephthalate; Polymer matrix composites; Polymerization; Polymerization kinetics; Radiation Dosage; Raman spectroscopy; Random Allocation; Resin composite; Samples; Statistical analysis; Statistical methods; Temperature; Time Factors; Germany; Liechtenstein; Degree of conversion; Resin composite; Temperature; Polymerization kinetics; Raman spectroscopy; Methacrylate
• ISSN: 0300-5712; 1879-176X
• DOI: 10.1016/j.jdent.2014.08.004

Abstract Objectives To investigate the 24 h post-cure polymerization and the effect of temperature on the post-cure polymerization of one conventional and three bulk-fill composite materials. Methods A conventional composite GrandioSO (GR) and three bulk-fill composites: Tetric EvoCeram Bulk Fill (TECBF), Quixfil (QF) and X-tra fil (XF) were investigated. The samples were cured for 20 s with irradiance of 1090 mW/cm2 . Composite samples were divided into two groups: the “room-temperature” group (RT, n = 5) and the “body-temperature” group (BT, n = 5) and they were stored in dark at 20 °C and 37 °C, respectively. Measurements of degree of conversion (DC) were made immediately after curing (0 h) and 24 h post-cure (24 h). To analyse the extent of post-cure DC increase, the DC values of 0 h-RT/24 h-RT and 0 h-BT/24 h-BT were compared. To analyse the difference in DC between RT and BT, the DC values of 0 h-RT/0 h-BT and 24 h-RT/24 h-BT were compared. Results DC increase 24 h post-cure was significant for all composites and ranged between 6.3% and 8.2% in RT and between 12.5% and 15.7% in BT. All composites demonstrated a higher DC in 24 h-BT compared to 24 h-RT. The difference was statistically significant for GR, TECBF and QF. Conclusions All composites demonstrated a significant post-cure effect after 24 h. Post-cure temperature increase from 20 °C to 37 °C yielded a higher post-cure DC increase. Clinical significance Due to the temperature effect on the final DC, studies performed at composite samples at room temperature may record more inferior properties than these attained in the oral cavity.