title: Temperature rise during photo-polymerization under ceramic restorations.
abstract: OBJECTIVE
  The aim of this study was to measure the temperature increase induced by various light-curing units during photo-polymerization beneath ceramic restorations.
  
  
  METHODS
  Three light-curing units were used; a high intensity QTH unit Elipar 2500 and two LED units: Translux Power Blue and Excelled 1400. The 15 ceramic specimens (CEREC Blocks) used in this study were of 2.5 mm thickness, 5 mm wide and 6 mm long and made using a slow speed saw. Using the same slow speed saw the occlusal enamel portion of 15 mandibular third molars was removed and 15 dentin discs of 1 mm height were prepared. The thickness of the luting cement was delimited to 0.5 mm, using a Teflon mold and then brought into contact with the dentin disc. Light-curing time for all the groups was 20 sec. The temperature rise was measured placing underneath the dentin disc a K-type thermocouple wire connected to a data logger. Five measurements were carried out for each group. Statistical analysis was performed using ANOVA (a=0.05).
  
  
  RESULTS
  The results indicated that there was a lower temperature rise induced from Translux Power Blue than from the other two light-curing units, which did not present statistically significant difference (p<0.05). However, temperature rise from the light-curing units used in this study is lower than 5.5°C, which is the limit of pulpal damage.
  
  
  CONCLUSIONS
  Within the limitations of this study, although the type and characteristics of light-curing units may affect temperature rise under ceramic restorations, this influence is possibly not of clinical significance.
authors.affiliation: Department of Operative Dentistry, School of Dentistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece, Tel: +302310999579; Fax: +302310999599; e-mail: ddiondent@gmail.com.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Dionysopoulos
authors.forename: Constantinos
authors.initials: C
authors.lastname: Papadopoulos
authors.forename: Pantelis
authors.initials: P
authors.lastname: Kouros
authors.forename: Effrosyni
authors.initials: E
authors.lastname: Tsitrou
authors.forename: Eugenia
authors.initials: E
authors.lastname: Koliniotou-Koumpia