title: Effect of irrigants on the survival of human stem cells of the apical papilla in a platelet-rich plasma scaffold in human root tips.
abstract: BACKGROUND
  Intracanal disinfection is a crucial step in regenerative endodontic procedures. However, this novel endodontic treatment lacks standardization, and numerous treatment protocols have been reported without knowledge of the effect of disinfection protocols on the survival of stem cells. The aim of this study was to test the hypothesis that different root canal irrigation protocols alter survival of stem cells from the apical papilla (SCAP).
  
  
  METHODS
  SCAP were isolated from immature human third molars, and a subpopulation of STRO-1 expressing cells was selected and expanded in vitro. Standardized human root segments (n = 5/group) were irrigated with 1 of 4 protocols: (1) 17% ethylenediaminetetraacetic acid (EDTA), (2) 6% NaOCl/17% EDTA/6% NaOCl, (3) 17% EDTA/2% chlorhexidine (CHX), or (4) 6% NaOCl/17% EDTA/6% NaOCl/isopropyl alcohol/2% CHX. Subsequently, STRO-1-enriched SCAP were mixed with platelet-rich-plasma, seeded into the root tips, and cultured for 21 days. Roots were then decalcified, processed for immunohistochemistry, and stained for vimentin and TO-PRO-3. The proportion of viable (vimentin-positive) cells was calculated on the basis of the total cell counts (TO-PRO-3) for each group.
  
  
  RESULTS
  Irrigation with 17% EDTA best supported cell survival (89% viability; P < .001 versus all other groups), followed by irrigation with 6% NaOCl/17% EDTA/6% NaOCl (74%; P < .001 versus the 2 groups containing 2% CHX). Conversely, protocols that included 2% CHX lacked any viable cells.
  
  
  CONCLUSIONS
  Collectively, the results suggest that irrigants alone greatly affect the survivability of STRO-1-enriched SCAP within the root canal environment and that inclusion of EDTA in irrigation protocols might be beneficial in regenerative procedures.
authors.affiliation: Department of Endodontics, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.
authors.forename: Ernesto G
authors.initials: EG
authors.lastname: Trevino
authors.forename: Amol N
authors.initials: AN
authors.lastname: Patwardhan
authors.forename: Michael A
authors.initials: MA
authors.lastname: Henry
authors.forename: Griffin
authors.initials: G
authors.lastname: Perry
authors.forename: Nicholas
authors.initials: N
authors.lastname: Dybdal-Hargreaves
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Hargreaves
authors.forename: Anibal
authors.initials: A
authors.lastname: Diogenes
mesh_terms: D000293:Adolescent; D000328:Adult; D000954:Antigens, Surface / Q000096:biosynthesis; D002448:Cell Adhesion / Q000187:drug effects; D002469:Cell Separation; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D016009:Chi-Square Distribution; D002710:Chlorhexidine / Q000633:toxicity; D003771:Dental Papilla / Q000166:cytology*; D003786:Dental Pulp Cavity / Q000502:physiology*; D004492:Edetic Acid / Q000494:pharmacology; D005260:Female; D006801:Humans; D008297:Male; D059630:Mesenchymal Stem Cells / Q000187:drug effects* / Q000378:metabolism; D018613:Microscopy, Confocal; D008954:Models, Biological; D053657:Platelet-Rich Plasma; D012038:Regeneration; D012388:Root Canal Irrigants / Q000494:pharmacology* / Q000633:toxicity; D012973:Sodium Hypochlorite / Q000633:toxicity; D054457:Tissue Scaffolds; D019227:Tooth Apex / Q000502:physiology*; D014746:Vimentin / Q000096:biosynthesis; D055815:Young Adult
chemical_list: D000954:Antigens, Surface; D012388:Root Canal Irrigants; C525591:STRO-1 antigen, human; D014746:Vimentin; D004492:Edetic Acid; D012973:Sodium Hypochlorite; D002710:Chlorhexidine