title: Ca(OH)2 application modes: in vitro alkalinity and clinical effect on bacteria.
abstract: OBJECTIVE
  To compare five calcium hydroxide (CH) products, CH-gutta-percha Plus points(®) (CHGP) and conventional CH paste, for their ability to maintain alkalinity and to assess the clinical antimicrobial effect of CHGP.
  
  
  METHODS
  Calcium hydroxide products were tested in the presence of standardized dentine powder or by titrating them with 1 mol HCl, expressed in mL (±SD). In a clinical trial, 21 single-rooted teeth with primary apical periodontitis were medicated with CHGP or with conventional CH paste. Bacterial samples were taken before and after chemo-mechanical preparation, after dressing and after leaving canals empty but sealed. To compare groups, anova with Tukey's test was used in the laboratory study and Fisher's exact test in the clinical study. Significance level was set at 5%.
  
  
  RESULTS
  Pure CH with water (8.5 ± 0.1) and Calasept (9.3 ± 0.1) maintained the highest alkalinity, followed by the gel-like products DS CaOH gel (7.3 ± 0.3) and Ultracal XS (6.8 ± 0.2) and then Biokalkki (6.3 ± 0.3) and Calxyl blue (5.1 ± 0.2). All CH paste products had higher values compared with CHGP (1.6 ± 0.1) (P < 0.05). Saturated solutions of the products were all neutralized to pH 8.6 within 24 h by dentine powder addition. Clinically, culture-negative results were obtained in 5/10 canals in the CHGP group and 7/11 with conventional CH (P > 0.05).
  
  
  CONCLUSIONS
  Aqueous CH mixtures kept high pH better than viscous gel products or CHGP. Dentine powder had equal buffering effect on each product tested. CHGP and traditional CH paste both had an antimicrobial effect in the clinical setting, but there was no significant difference between the groups.
authors: Department of Oral Infectious Diseases, University of Helsinki, Helsinki, Finland.
authors: E K
authors: EK
authors: Sirén
authors: E
authors: E
authors: Kerosuo
authors: E
authors: E
authors: Lavonius
authors: J H
authors: JH
authors: Meurman
authors: M
authors: M
authors: Haapasalo
mesh_terms: D000468:Alkalies / Q000737:chemistry*; D001419:Bacteria / Q000187:drug effects*; D002126:Calcium Hydroxide / Q000008:administration & dosage*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques
chemical_list: D000468:Alkalies; D002126:Calcium Hydroxide
keywords: Ca(OH)2; alkalinity; bacteria; clinical trial; gutta-percha; root canal therapy