title: Calcium release and pH-characteristics of calcium hydroxide plus points.
abstract: OBJECTIVE
  To evaluate calcium ion release and pH-characteristics of calcium hydroxide plus points (CHPP), conventional calcium hydroxide points (CHP, both Coltène/Whaledent, Langenau, Germany) and aqueous calcium hydroxide suspension (CHS) (Calxyl, OCO, Dirmstein, Germany).
  
  
  METHODS
  Ten CHPP or CHP of size 50 were immersed into 5 mL isotonic sodium chloride solution. Conventional Ca(OH)2-free gutta-percha points served as negative control. Calcium release was measured up to 44 days by means of complexometric titration. Time dependent pH behaviour of all points in comparison with CHS was determined immersing 30 points of size 50 into 2.3 mL 0.9% wt NaCl-solution at time intervals of 0.5-72 h by a microelectrode measuring chain and a pH-meter. The surface morphologies of new and used gutta-percha points were evaluated qualitatively under a scanning electron microscope. Statistical evaluation was carried out using Kolmogorov-Smirnov-tests, Mann-Whitney-tests and multifactorial anova.
  
  
  RESULTS
  For CHPP, a threefold greater calcium release was measured compared with CHP. Both types of points as well as CHS showed a maximum pH of approximately 12. Differences between groups were statistically significant for calcium release and pH (multifactorial anova; P < 0.001). Both types of points showed porous surfaces after usage, with a rougher surface for CHPP.
  
  
  CONCLUSIONS
  CHPP and CHP increased the pH of isotonic sodium chloride >11 within 3 min. CHPP had a greater release of Ca2+ compared with CHP.
authors.affiliation: Dental Clinic 1--Operative Dentistry and Periodontology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Lohbauer
authors.forename: G
authors.initials: G
authors.lastname: Gambarini
authors.forename: J
authors.initials: J
authors.lastname: Ebert
authors.forename: W
authors.initials: W
authors.lastname: Dasch
authors.forename: A
authors.initials: A
authors.lastname: Petschelt
mesh_terms: D000704:Analysis of Variance; D002118:Calcium / Q000737:chemistry; D017610:Calcium Compounds / Q000737:chemistry; D002126:Calcium Hydroxide / Q000737:chemistry*; D006171:Gutta-Percha / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D010087:Oxides / Q000737:chemistry; D012387:Root Canal Filling Materials / Q000737:chemistry*; D012388:Root Canal Irrigants / Q000737:chemistry*; D018709:Statistics, Nonparametric
chemical_list: D017610:Calcium Compounds; D010087:Oxides; D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; D006171:Gutta-Percha; C016538:lime; D002126:Calcium Hydroxide; D002118:Calcium