title: Effects of intrapulpal temperature change induced by visible light units on the metabolism of odontoblast-like cells.
abstract: OBJECTIVE
  To investigate the effects of intrapulpal temperature changes induced by a quartz tungsten halogen (QTH) and a light emitting diode (LED) curing units on the metabolism of odontoblast-like cells.
  
  
  METHODS
  Thirty-six 0.5 mm-thick dentin discs obtained from sound human teeth were randomly assigned into three groups: QTH, LED and no light (control). After placement of the dentin discs in pulp chamber devices, a thermistor was attached to the pulpal surface of each disc and the light sources were applied on the occlusal surface. After registering the temperature change, odontoblast-like cells MDPC-23 were seeded on the pulpal side of the discs and the curing lights were again applied. Cell metabolism was evaluated by the MTT assay and cell morphology was assessed by SEM.
  
  
  RESULTS
  In groups QTH and LED the intrapulpal temperature increased by 6.4 degrees C and 3.4 degrees C, respectively. The difference between both groups was statistically significant (Mann-Whitney; P < 0.05). QTH and LED reduced the cell metabolism by 36.4% and 33.4%, respectively. Regarding the cell metabolism, no statistically significant difference was observed between both groups (Mann-Whitney; P > 0.05). However, when compared to the control, only QTH significantly reduced the cell metabolism (Mann-Whitney; P < 0.05). It was concluded that the irradiance of 0.5 mm-thick human dentin discs with a QTH in comparison to a LED curing unit promoted a higher temperature rise, which propagates through the dentin negatively affecting the metabolism of the underlying cultured pulp cells.
authors: Department of Biochemistry and Immunology, Faculty of Medicine, University of São Paulo, USP, São Paulo, Brazil.
authors: Pedro Paulo Chaves
authors: PP
authors: de Souza
authors: Josimeri
authors: J
authors: Hebling
authors: Mariana Grecco
authors: MG
authors: Scalon
authors: Andreza Maria Fábio
authors: AM
authors: Aranha
authors: Carlos Alberto de Souza
authors: CA
authors: Costa
mesh_terms: D001831:Body Temperature / Q000528:radiation effects*; D002461:Cell Line, Transformed; D055117:Curing Lights, Dental / Q000009:adverse effects*; D003782:Dental Pulp / Q000166:cytology / Q000502:physiology / Q000528:radiation effects*; D006219:Halogens; D006801:Humans; D009804:Odontoblasts / Q000378:metabolism / Q000528:radiation effects*; D012666:Semiconductors
chemical_list: D006219:Halogens