title: Effect of three calcium hydroxide formulations on fracture resistance of dentin over time.
abstract: BACKGROUND
  The long-term use of calcium hydroxide has been discouraged throughout the recent decade due to a proposed decrease in fracture resistance of dentin. This weakening has grave implications when used on immature teeth with thin dentinal walls in procedures such as apexogenesis.
  
  
  OBJECTIVE
  The purpose of this study was to identify the effects of three commercial calcium hydroxide formulations (Vitapex, Ultracal XS and Pulpdent) on the fracture resistance of dentin in relation to time.
  
  
  METHODS
  Two-hundred and forty deciduous lamb incisors were collected, cleaned and shaped, and filled with one of the three calcium hydroxide formulations and one negative saline control. At one, three, and 6 months, these teeth were fractured on an Instron machine to determine fracture resistance.
  
  
  RESULTS
  No statistical differences were observed among any of the experimental groups, nor between any of the experimental groups and negative control groups.
  
  
  CONCLUSIONS
  Based on our findings, there appears insufficient evidence to support that either Vitapex, Ultracal XS, or Pulpdent will cause a decrease in fracture resistance of dentin within a 6-month period.
authors.affiliation: Department of Endodontics, Loma Linda School of Dentistry, Loma Linda, CA, USA.
authors.forename: Jeremiah James
authors.initials: JJ
authors.lastname: Hawkins
authors.affiliation: Department of Endodontics, Loma Linda School of Dentistry, Loma Linda, CA, USA.
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Torabinejad
authors.affiliation: Department of Endodontics, Loma Linda School of Dentistry, Loma Linda, CA, USA.
authors.forename: Yiming
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Endodontics, Loma Linda School of Dentistry, Loma Linda, CA, USA.
authors.forename: Bonnie
authors.initials: B
authors.lastname: Retamozo
mesh_terms: D000818:Animals; D002126:Calcium Hydroxide / Q000494:pharmacology*; D003799:Dental Stress Analysis; D003804:Dentin / Q000187:drug effects*; D007180:Incisor; D012387:Root Canal Filling Materials / Q000494:pharmacology; D012388:Root Canal Irrigants / Q000494:pharmacology*; D034561:Sheep, Domestic; D012828:Silicones / Q000494:pharmacology*; D013997:Time Factors; D014082:Tooth Fractures / Q000517:prevention & control*
chemical_list: D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; D012828:Silicones; C531021:UltraCal XS; C029584:calcium hydroxide, iodoform, silicone oil drug combination; C029777:Pulpdent; D002126:Calcium Hydroxide
keywords: crown fracture; crown-root fracture; dental trauma; permanent tooth; root fracture; tooth injury