title: Antimicrobial photodynamic therapy for the treatment of teeth with apical periodontitis: a histopathological evaluation.
abstract: BACKGROUND
  This study evaluated the in vivo response of apical and periapical tissues of dogs' teeth with apical periodontitis after one-session endodontic treatment with and without antimicrobial photodynamic therapy (aPDT).
  
  
  METHODS
  Sixty root canals with experimentally induced apical periodontitis were instrumented and assigned to 4 groups receiving aPDT and root canal filling (RCF) or not: group aPDT+/RCF+ (n = 20): aPDT (photosensitizer phenothiazine chloride at 10 mg/mL for 3 minutes and diode laser [λ = 660 nm, 60 mW/cm(2)] for 1 minute) and RCF in the same session; group aPDT+/RCF- (n = 10); group aPDT-/RCF+ (n = 20), and group aPDT-/RCF- (n = 10). Teeth were restored, and the animals were killed after 90 days. Sections from the maxillas and mandibles were stained with hematoxylin-eosin and Mallory trichrome and examined under light microscopy. Descriptive (ie, newly formed apical mineralized tissue, periapical inflammatory infiltrate, apical periodontal ligament thickness, and mineralized tissue resorption) and quantitative (ie, periapical lesion size and number of inflammatory cells) microscopic analysis was performed. Quantitative data were analyzed by the Kruskal-Wallis and Dunn tests (α = .05).
  
  
  RESULTS
  In the aPDT-treated groups, the periapical region was moderately/severely enlarged with no inflammatory cells, moderate neoangiogenesis and fibrogenesis, and the smallest periapical lesions.
  
  
  CONCLUSIONS
  Although apical closure by mineralized tissue deposition was not achieved, the absence of inflammatory cells, moderate neoangiogenesis, and fibrogenesis in the periapical region in the groups treated with aPDT indicate that this can be a promising adjunct therapy to cleaning and shaping procedures in teeth with apical periodontitis undergoing one-session endodontic treatment.
authors.affiliation: Department of Pediatric Dentistry, Preventive and Community Dentistry, Dental School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil. lea@forp.usp.br
authors.forename: Lea Assed Bezerra
authors.initials: LA
authors.lastname: Silva
authors.forename: Arthur B
authors.initials: AB
authors.lastname: Novaes
authors.forename: Rafael R
authors.initials: RR
authors.lastname: de Oliveira
authors.forename: Paulo
authors.initials: P
authors.lastname: Nelson-Filho
authors.forename: Milton
authors.initials: M
authors.lastname: Santamaria
authors.forename: Raquel Assed Bezerra
authors.initials: RA
authors.lastname: Silva
mesh_terms: D016301:Alveolar Bone Loss / Q000473:pathology; D000818:Animals; D000890:Anti-Infective Agents / Q000627:therapeutic use*; D001641:Bicuspid / Q000473:pathology; D003238:Connective Tissue / Q000187:drug effects / Q000473:pathology; D003789:Dental Pulp Exposure / Q000382:microbiology; D004285:Dogs; D054023:Lasers, Semiconductor / Q000627:therapeutic use; D018919:Neovascularization, Physiologic / Q000187:drug effects; D010485:Periapical Periodontitis / Q000188:drug therapy* / Q000473:pathology; D010486:Periapical Tissue / Q000187:drug effects / Q000473:pathology; D010513:Periodontal Ligament / Q000187:drug effects / Q000473:pathology; D010640:Phenothiazines / Q000627:therapeutic use*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D018915:Root Canal Preparation / Q000379:methods; D012390:Root Canal Therapy / Q000379:methods*; D012391:Root Resorption / Q000473:pathology; D013997:Time Factors; D019227:Tooth Apex / Q000187:drug effects / Q000473:pathology
chemical_list: D000890:Anti-Infective Agents; D010640:Phenothiazines; D017319:Photosensitizing Agents; C031637:phenothiazine