title: Evaluation of the effect of EDTA, EDTAC and citric acid on the microhardness of root dentine.
abstract: OBJECTIVE
  To evaluate the effect of citric acid, ethylenediaminetetraacetic acid (EDTA) and ethylenediaminetetraacetic acid plus Cetavlon (EDTAC) solutions on the microhardness of human root canal dentine.
  
  
  METHODS
  Sixteen maxillary human canines were sectioned transversely at the cemento-enamel junction and the crowns were discarded. Subsequently, each root was embedded in an epoxy resin cylinder and their middle third sectioned horizontally into 4 mm thick slices. The samples were randomly divided into three groups according to the chelating agent employed, as follows (n = 6): group 1: EDTA 17%, group 2: EDTAC 17% and group 3: citric acid 10%. Dentine microhardness was then measured with a load of 50 g for 15 s. At the beginning of the experiment, reference microhardness values were obtained for samples without any etching (t = 0 min). The same samples were then exposed to 50 microL of the chelator solution for 1, 3 and 5 min. The Student's t-test (P < 0.05) was used to compare results for different times for each chelator and different chelators for each time.
  
  
  RESULTS
  Microhardness decreased with increasing time of application of chelating solutions. There were no significant (P > 0.05) differences between initial microhardness for the three groups as well as after 1 min of application of the substances. After 3 min, EDTA produced a significantly greater reduction in microhardness. However, there was no significant difference between EDTA and EDTAC after 5 min. Citric acid caused significantly less reduction in microhardness.
  
  
  CONCLUSIONS
  Overall, citric acid was least effective in reducing dentine hardness whilst EDTA had the strongest effect.
authors.affiliation: Department of Endodontics, Rio de Janeiro State University, Rio de Janeiro, Brazil. endogus@gmail.com
authors.forename: G
authors.initials: G
authors.lastname: De-Deus
authors.forename: S
authors.initials: S
authors.lastname: Paciornik
authors.forename: M H P
authors.initials: MH
authors.lastname: Mauricio
mesh_terms: D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000494:pharmacology; D002614:Chelating Agents / Q000494:pharmacology*; D019343:Citric Acid / Q000494:pharmacology*; D003764:Dental Materials / Q000494:pharmacology*; D003804:Dentin / Q000187:drug effects*; D003902:Detergents / Q000494:pharmacology; D004492:Edetic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology*; D006244:Hardness; D006801:Humans; D007091:Image Processing, Computer-Assisted; D013314:Stress, Mechanical; D013997:Time Factors; D014092:Tooth Root / Q000187:drug effects*
chemical_list: D002593:Cetrimonium Compounds; D002614:Chelating Agents; D003764:Dental Materials; D003902:Detergents; D019343:Citric Acid; C033443:EDTAC; D004492:Edetic Acid; D000077286:Cetrimonium