title: Kinetics of pulpal temperature rise during light curing of 6 bonding agents from different generations, using light emitting diode and quartz-tungsten-halogen units: An in-vitro simulation.
abstract: BACKGROUND
  Application of bonding agents (BA) into deep cavities and light curing them might increase pulpal temperature and threaten its health. The purpose of this study was to evaluate temperature rise of pulp by light curing six BA using two different light curing units (LCU), through a dent in wall of 0.5 mm.
  
  
  METHODS
  This in vitro experiment was carried out on 96 slices of the same number of human third molars (6 BAs × 2 LCUs × 8 specimens in each group). There were 6 groups of BAs: N Bond, G-Bond, OptiBond XTR, Clearfil SE, Adper Single Bond 2 and V Bond. Each group of BA (n = 16) had two subgroups of light emitting diode (LED) and quartz-tungsten-halogen light cure units (n = 8). Each of these 16 specimens were subjected to light emitting for 20 s, once without any BAs (control) and later when a BA was applied to surface of disk. Temperature rises in 140 s were evaluated. Their mean temperature change in first 20 s were calculated and analyzed using two-way repeated-measures and one-way analysis of variance (ANOVA) and Tukey (α = 0.05). Furthermore rate of temperature increase was calculated for each material and LCU.
  
  
  RESULTS
  Minimum and maximum temperature rises in all subgroups were 1.7 and 2.8°C, respectively. Repeated measures ANOVA showed that both of adhesive and LCU types had significant effect on temperature rise after application of adhesives. Tukey post-hoc analysis showed Clearfil SE showed significantly higher temperature rise in comparison with Adper Single bond 2 (P = 0.047) and N Bond (P = 0.038). Temperature rose in a linear fashion during first 30-40 s and after that it was non-linear.
  
  
  CONCLUSIONS
  20 s of light curing seems safe for pulpal health (with critical threshold of 5.5°C). However, in longer durations and especially when using LED units, the process should be broken to two sessions.
authors: Department of Dental Biomaterials, Tehran University of Medical Sciences, Tehran, Iran.
authors: Najmeh Khatoon
authors: NK
authors: Khaksaran
authors: Iranian Tissue Bank and Research Center, Department of Dental Materials, Faculty of Dentistry, Research Center for Sciences and Technology in Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors: Tahereh Jafarzadeh
authors: TJ
authors: Kashi
authors: Iranian Tissue Bank and Research Center, Tehran University of Medical Sciences, Department of Dental Anatomy and Morphology, Dental Branch, Islamic Azad University, Iran.
authors: Vahid
authors: V
authors: Rakhshan
authors: Department of Dental Biomaterials, Tehran University of Medical Sciences, Tehran, Iran.
authors: Zahra Sadat
authors: ZS
authors: Zeynolabedin
authors: Department of Dental Biomaterials, School of Dentistry and Research Center for Science and Technology in Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors: Hossein
authors: H
authors: Bagheri
keywords: Composite resins; dental materials; differential thermal analysis; polymerization