title: The effect of 8.25% sodium hypochlorite on dental pulp dissolution and dentin flexural strength and modulus.
abstract: BACKGROUND
  The purpose of this study was to evaluate the effect of various concentrations of sodium hypochlorite (NaOCl), including 8.25%, on dental pulp dissolution and dentin flexural strength and modulus.
  
  
  METHODS
  Sixty dental pulp samples and 55 plane parallel dentin bars were retrieved from extracted human teeth. Five test groups (n = 10) were formed consisting of a pulp sample and dentin bar immersed in various NaOCl solutions. The negative control group (n = 5) consisted of pulp samples and dentin bars immersed in saline. The positive control group (n = 5) consisted of pulp samples immersed in 8.25% NaOCl without a dentin bar. Every 6 minutes for 1 hour, the solutions were refreshed. The dentin bars were tested for flexural strength and modulus with a 3-point bend test. The time until total pulp dissolution and any changes in dentin bar flexural strength and modulus for the different NaOCl solutions were statistically analyzed.
  
  
  RESULTS
  An increase in NaOCl concentration showed a highly significant decrease in pulp dissolution time. The pulp dissolution property of 8.25% NaOCl was significantly faster than any other tested concentration of NaOCl. The presence of dentin did not have a significant effect on the dissolution capacity of NaOCl if the solutions were refreshed. NaOCl concentration did not have a statistically significant effect on dentin flexural strength or modulus.
  
  
  CONCLUSIONS
  Dilution of NaOCl decreases its pulp dissolution capacity. Refreshing the solution is essential to counteract the effects of dentin. In this study, NaOCl did not have a significant effect on dentin flexural strength or modulus.
authors: Wilford Hall Department of Endodontics, Joint Base San Antonio-Lackland, Texas and Keesler Medical Center Department of Endodontics, Keesler Air Force Base, Biloxi, Mississippi. Electronic address: james.cullen@us.af.mil.
authors: James K T
authors: JK
authors: Cullen
authors: Wilford Hall Department of Endodontics, Joint Base San Antonio-Lackland, Texas and Keesler Medical Center Department of Endodontics, Keesler Air Force Base, Biloxi, Mississippi.
authors: James A
authors: JA
authors: Wealleans
authors: Wilford Hall Department of Endodontics, Joint Base San Antonio-Lackland, Texas and Keesler Medical Center Department of Endodontics, Keesler Air Force Base, Biloxi, Mississippi.
authors: Timothy C
authors: TC
authors: Kirkpatrick
authors: Wilford Hall Department of Endodontics, Joint Base San Antonio-Lackland, Texas and Keesler Medical Center Department of Endodontics, Keesler Air Force Base, Biloxi, Mississippi.
authors: John M
authors: JM
authors: Yaccino
mesh_terms: D003782:Dental Pulp / Q000187:drug effects*; D003799:Dental Stress Analysis; D003804:Dentin / Q000187:drug effects* / Q000502:physiology; D004548:Elasticity; D006801:Humans; D008963:Molar; D012388:Root Canal Irrigants / Q000008:administration & dosage*; D012973:Sodium Hypochlorite / Q000008:administration & dosage*; D013314:Stress, Mechanical
chemical_list: D012388:Root Canal Irrigants; D012973:Sodium Hypochlorite
keywords: Dental pulp; dentin; dissolution; flexural modulus; flexural strength; sodium hypochlorite