title: The effect of medicaments used in endodontic regeneration on root fracture and microhardness of radicular dentine.
abstract: OBJECTIVE
  To investigate the effect of medicaments used in endodontic regeneration on root fracture resistance and microhardness of radicular dentine.
  
  
  METHODS
  The root canals of mandibular premolars (n = 180) were instrumented and randomized into three treatment groups and an untreated control group. Each treatment group received either triple antibiotic paste (TAP), double antibiotic paste (DAP) or calcium hydroxide paste [Ca(OH)₂] intracanal medicament. Teeth were kept in saline for 1 week, 1 month or 3 months. After each time-point, 15 teeth were randomly selected from each group and two root cylinders were obtained from each tooth. One cylinder was subjected to a fracture resistance test, and the other cylinder was used for a microhardness test. Two-way ANOVA and Tukey's pairwise comparisons were used for statistical analysis.
  
  
  RESULTS
  For the microhardness test, the two-way interaction between group and time was significant (P < 0.001). The intracanal application of TAP and DAP caused significant and continuous decrease in root dentine microhardness after one (P < 0.05) and 3 months (P < 0.001), respectively. The three-month intracanal application of Ca(OH)₂ significantly increased the microhardness of root dentine (P < 0.05). The time factor had a significant effect on fracture resistance (P < 0.001). The three intracanal medicaments caused significant decreases in fracture resistance ranging between 19% and 30% after 3-month application compared to 1-week application.
  
  
  CONCLUSIONS
  In this laboratory study, the 3-month application of triple antibiotic paste, double antibiotic paste or calcium hydroxide paste medicaments significantly reduced the root fracture resistance of extracted teeth compared to a 1-week application.
authors: Department of Restorative Dentistry, Division of Dental Biomaterials, Indiana University School of Dentistry, Indianapolis, IN 46202, USA. gyassen@iupui.edu
authors: G H
authors: GH
authors: Yassen
authors: M M
authors: MM
authors: Vail
authors: T G
authors: TG
authors: Chu
authors: J A
authors: JA
authors: Platt
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage; D056624:Apexification / Q000379:methods*; D001641:Bicuspid / Q000187:drug effects; D002126:Calcium Hydroxide / Q000627:therapeutic use; D002939:Ciprofloxacin / Q000008:administration & dosage; D003804:Dentin / Q000187:drug effects* / Q000648:ultrastructure; D004338:Drug Combinations; D006244:Hardness; D006801:Humans; D008422:Materials Testing; D008795:Metronidazole / Q000008:administration & dosage; D008855:Microscopy, Electron, Scanning; D008911:Minocycline / Q000008:administration & dosage; D012388:Root Canal Irrigants / Q000627:therapeutic use*; D018915:Root Canal Preparation / Q000379:methods; D016369:Smear Layer; D013997:Time Factors; D014082:Tooth Fractures / Q000503:physiopathology*; D014092:Tooth Root / Q000187:drug effects* / Q000293:injuries / Q000648:ultrastructure
chemical_list: D000900:Anti-Bacterial Agents; D004338:Drug Combinations; D012388:Root Canal Irrigants; D008795:Metronidazole; D002939:Ciprofloxacin; D008911:Minocycline; D002126:Calcium Hydroxide