title: Influence of the degree of dentine mineralization on pulp chamber temperature increase during resin-based composite (RBC) light-activation.
abstract: OBJECTIVE
  To analyse the influence of the degree of dentine mineralization on the pulp chamber temperature increase during composite light-activation.
  
  
  METHODS
  Dentine discs (2mm thick) obtained from recently extracted teeth or those with extensive dentine sclerosis were analysed by FT-IR spectrometry in order to choose the two discs with the greatest difference in the degree of mineralization. A model tooth was set up with the dentine discs between a molar with the pulp chamber exposed and a crown with a standardized class II cavity. A K-type thermocouple was introduced into the molar root until it came into contact with the dentine discs and the cavity was filled with P60 resin composite. The temperature rise was measured for 120s after light-activation began: Standard (S) 600 mW/cm(2)/40s; Ramp (R) 0-->800 mW/cm(2)/10s+800 mW/cm(2)/10s; Boost (B) 85 0mW/cm(2)/10s and LED (L) 1.300 mW/cm(2)/40s (n=10). The same protocol was repeated after grinding the dentine discs to 1.0 and 0.5mm thickness.
  
  
  RESULTS
  The temperature increase was significantly higher in dentine with high degree of mineralization (p<0.05). With respect to the dentine thickness, the following result was found: 2mm<1mm<0.5mm (p<0.05). The light-activation mode also presented significant difference as follows: S>R=L>B (p<0.05).
  
  
  CONCLUSIONS
  The higher the degree of dentine mineralization the greater the increase in pulp chamber temperature. The temperature increase was influenced by the light-polymerization mode and dentine thickness.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, Federal Fluminense University, CEP 24040-110, Niterói, Rio de Janeiro, Brazil. emsilva@vm.uff.br
authors.forename: Eduardo Moreira
authors.initials: EM
authors.lastname: da Silva
authors.forename: Alice Gonçalves
authors.initials: AG
authors.lastname: Penelas
authors.forename: Michele Silveira
authors.initials: MS
authors.lastname: Simão
authors.forename: Jaime Dutra Noronha
authors.initials: JD
authors.lastname: Filho
authors.forename: Laiza Tatiana
authors.initials: LT
authors.lastname: Poskus
authors.forename: José Guilherme Antunes
authors.initials: JG
authors.lastname: Guimarães
mesh_terms: D001831:Body Temperature / Q000502:physiology*; D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects*; D055117:Curing Lights, Dental; D003737:Dental Cavity Preparation; D003764:Dental Materials / Q000737:chemistry / Q000528:radiation effects*; D003782:Dental Pulp / Q000503:physiopathology; D003786:Dental Pulp Cavity / Q000502:physiology*; D003789:Dental Pulp Exposure / Q000503:physiopathology; D003804:Dentin / Q000033:anatomy & histology / Q000502:physiology*; D003809:Dentin, Secondary / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D011829:Radiation Dosage; D017550:Spectroscopy, Fourier Transform Infrared; D013821:Thermometers; D013997:Time Factors; D014074:Tooth Calcification / Q000502:physiology*
chemical_list: D003188:Composite Resins; D003764:Dental Materials; C438835:Filtek P60 Composite Resin