title: Assessment of a gel-type chelating preparation containing 1-hydroxyethylidene-1, 1-bisphosphonate.
abstract: OBJECTIVE
  To test an aqueous gel containing 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) regarding its interactions with sodium hypochlorite, its calcium binding capacity, and its potential in preventing the formation of a smear layer when used in conjunction with rotary root canal preparation.
  
  
  METHODS
  The experimental aqueous gel consisted of (w/v) 2% alginate, 3% aerosil, 10% Tween 80 and 18% HEBP. Interactions of gel components with hypochlorite were assessed using iodometric titration and monochromatic ultraviolet spectrometry. Two commercial paste-type chelators containing ethylenediaminetetraacetic acid (EDTA) and peroxide (RC-Prep and Glyde) served as controls. Calcium-binding capacities were measured in mixtures with a Ca2+ standard solution buffered at pH 10 using a calcium-selective measuring chain. Finally, root canals of 16 extracted single-rooted premolars per group were instrumented using ProFile instruments dipped in the experimental gel, RC-Prep, or nothing. Additionally, canals were rinsed with 10 mL of a 1% NaOCl solution during/after preparation. Smear scores in instrumented teeth were monitored using scanning electron microscopy.
  
  
  RESULTS
  None of the experimental gel components showed short-term interactions with hypochlorite, whilst EDTA, peroxide, RC-Prep and Glyde immediately reduced the hypochlorite in solution. The experimental gel chelated 30 mg Ca2+ g-1, compared with 16 mg Ca2+ g-1 and 11 mg Ca2+ g-1 chelated by RC-Prep and Glyde respectively. Smear scores obtained with the experimental gel were significantly (P<0.05) lower than with RC-Prep in coronal and middle root thirds, whilst no differences were observed in apical root thirds.
  
  
  CONCLUSIONS
  Under the conditions of this study, an HEBP gel appeared advantageous over currently available products.
authors.affiliation: Department of Preventive Dentistry, Periodontology, and Cariology, University of Zürich Center for Dental Medicine, Zürich, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Girard
authors.forename: F
authors.initials: F
authors.lastname: Paqué
authors.forename: M
authors.initials: M
authors.lastname: Badertscher
authors.forename: B
authors.initials: B
authors.lastname: Sener
authors.forename: M
authors.initials: M
authors.lastname: Zehnder
mesh_terms: D002118:Calcium / Q000737:chemistry; D002614:Chelating Agents / Q000737:chemistry* / Q000627:therapeutic use; D003786:Dental Pulp Cavity / Q000187:drug effects / Q000648:ultrastructure; D004492:Edetic Acid / Q000737:chemistry; D012968:Etidronic Acid / Q000737:chemistry* / Q000627:therapeutic use; D005782:Gels; D006801:Humans; D008422:Materials Testing; D010545:Peroxides / Q000737:chemistry; D012388:Root Canal Irrigants / Q000737:chemistry* / Q000627:therapeutic use; D018915:Root Canal Preparation; D016369:Smear Layer; D012973:Sodium Hypochlorite / Q000737:chemistry / Q000627:therapeutic use; D013056:Spectrophotometry, Ultraviolet; D017186:Titrimetry; D014508:Urea / Q000737:chemistry; D014885:Waxes / Q000737:chemistry
chemical_list: D002614:Chelating Agents; D005782:Gels; D010545:Peroxides; D012388:Root Canal Irrigants; D014885:Waxes; C025081:RC-Prep; D014508:Urea; D004492:Edetic Acid; D012973:Sodium Hypochlorite; D012968:Etidronic Acid; D002118:Calcium