title: Effect of ultrasonic activation on pH and calcium released by calcium hydroxide pastes in simulated external root resorption.
abstract: BACKGROUND
  The purpose of this study was to analyze the influence of ultrasonic activation of calcium hydroxide (CH) pastes on pH and calcium release in simulated external root resorptions.
  
  
  METHODS
  Forty-six bovine incisors had their canals cleaned and instrumented, and defects were created in the external middle third of the roots, which were then used for the study. The teeth were externally made impermeable, except for the defected area, and divided into the following 4 groups containing 10 samples each according to the CH paste and the use or not of the ultrasonic activation: group 1: propylene glycol without ultrasonic activation, group 2: distilled water without ultrasonic activation, group 3: propylene glycol with ultrasonic activation, and group 4: distilled water with ultrasonic activation. After filling the canals with the paste, the teeth were restored and individually immersed into flasks with ultrapure water. The samples were placed into other flasks after 7, 15, and 30 days so that the water pH level could be measured by means of a pH meter. Calcium release was measured by means of an atomic absorption spectrophotometer. Six teeth were used as controls. The results were statistically compared using the Kruskal-Wallis and Mann-Whitney U tests (P < .05).
  
  
  RESULTS
  For all periods analyzed, the pH level was found to be higher when the CH paste was activated with ultrasound. Calcium release was significantly greater (P < .05) using ultrasonic activation after 7 and 30 days.
  
  
  CONCLUSIONS
  The ultrasonic activation of CH pastes favored a higher pH level and calcium release in simulated external root resorptions.
authors.affiliation: Department of Operative Dentistry, Dental Materials and Endodontics, Dental School of Bauru, University of São Paulo, Bauru, São Paulo, Brazil. mhungaro@travelnet.com.br
authors.forename: Marco Antonio Hungaro
authors.initials: MA
authors.lastname: Duarte
authors.forename: Nickolas V
authors.initials: NV
authors.lastname: Balan
authors.forename: Marcia A
authors.initials: MA
authors.lastname: Zeferino
authors.forename: Rodrigo R
authors.initials: RR
authors.lastname: Vivan
authors.forename: Carlos Alberto H
authors.initials: CA
authors.lastname: Morais
authors.forename: Mário
authors.initials: M
authors.lastname: Tanomaru-Filho
authors.forename: Ronald
authors.initials: R
authors.lastname: Ordinola-Zapata
authors.forename: Ivalgo G
authors.initials: IG
authors.lastname: Moraes
mesh_terms: D000818:Animals; D002118:Calcium / Q000032:analysis*; D002126:Calcium Hydroxide / Q000737:chemistry*; D002417:Cattle; D006863:Hydrogen-Ion Concentration; D007180:Incisor; D019946:Propylene Glycol / Q000737:chemistry; D012388:Root Canal Irrigants / Q000737:chemistry*; D012391:Root Resorption / Q000628:therapy*; D013010:Sonication; D013054:Spectrophotometry, Atomic; D014867:Water
chemical_list: D012388:Root Canal Irrigants; D014867:Water; D019946:Propylene Glycol; D002126:Calcium Hydroxide; D002118:Calcium