title: Comparison of pH changes induced by calcium enriched mixture and those of calcium hydroxide in simulated root resorption defects.
abstract: BACKGROUND
  External resorption usually occurs after dental trauma and the loss of root cementum. Because it has the ability to induce alkaline pH, calcium hydroxide is used in treatment of external resorption, which is reportedly not free from disadvantages. Driven by such understanding, the aim of this in vitro study was to compare the pH changes induced by calcium enriched mixture (CEM) and those of calcium hydroxide in simulated root resorption defects.
  
  
  METHODS
  Twenty-one paired extracted human premolars were cut to the length of 14 mm. Root canal preparation was performed by using ProTaper rotary system. Cavities of 0.7-mm depth and 1.4-mm diameter were prepared on the external root surface, 5 mm from the apex. Half of the teeth were filled with CEM and the other half with calcium hydroxide. Five premolars were also assigned as the negative control group and filled with normal saline. To be assured of the filling quality, a radiograph was obtained from each tooth. Subsequently, pH of the cavity was measured with a microelectrode at 20-minute, 3-hour, and 1-, 7-, 14-, 21-, and 28-day intervals after filling.
  
  
  RESULTS
  Mean pH in the CEM and in the calcium hydroxide groups were significantly varied during the study period, with pH of the calcium hydroxide group significantly higher than that of CEM in all of the measurements. However, no significant difference was observed between the pH of the calcium hydroxide group and that of the control group at the 7-day and 14-day measurements and between those of the CEM group and the control group at days 7, 21, and 28.
  
  
  CONCLUSIONS
  In comparison with calcium hydroxide, CEM hardly maintained alkaline pH during the first month of use, and so CEM may be an inappropriate material in treatment of external root resorption.
authors.affiliation: Dental Materials Research Center, Faculty of Dentistry, Department of Endodontics, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Forghani
authors.affiliation: Private practice, Mashhad, Iran.
authors.forename: Hamzeh
authors.initials: H
authors.lastname: Mashhoor
authors.affiliation: Dental Research Center, Faculty of Dentistry, Department of Endodontics, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Armita
authors.initials: A
authors.lastname: Rouhani
authors.affiliation: Dental Research Center, Faculty of Dentistry, Department of Endodontics, Mashhad University of Medical Sciences, Mashhad, Iran. Electronic address: hamid_j365@yahoo.com.
authors.forename: Hamid
authors.initials: H
authors.lastname: Jafarzadeh
mesh_terms: D000468:Alkalies / Q000737:chemistry; D002118:Calcium / Q000737:chemistry* / Q000627:therapeutic use; D002126:Calcium Hydroxide / Q000737:chemistry* / Q000627:therapeutic use; D003786:Dental Pulp Cavity / Q000187:drug effects / Q000473:pathology; D003804:Dentin / Q000187:drug effects / Q000473:pathology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides / Q000737:chemistry; D008422:Materials Testing; D011897:Random Allocation; D012388:Root Canal Irrigants / Q000737:chemistry* / Q000627:therapeutic use; D012391:Root Resorption / Q000188:drug therapy / Q000503:physiopathology*; D013997:Time Factors; D019227:Tooth Apex / Q000187:drug effects / Q000473:pathology; D019553:Tooth, Nonvital / Q000150:complications
chemical_list: D000468:Alkalies; D006878:Hydroxides; D012388:Root Canal Irrigants; C031356:hydroxide ion; D002126:Calcium Hydroxide; D002118:Calcium
keywords: Calcium enriched mixture; calcium hydroxide; external resorption; pH