title: Levels of evidence for the outcome of regenerative endodontic therapy.
abstract: BACKGROUND
  The aim of this systematic review was to assign levels of evidence (LOEs) to existing clinical articles related to the outcome of regenerative endodontic therapy and to evaluate the clinical and radiographic outcomes of this treatment modality.
  
  
  METHODS
  Electronic search was executed in PubMed, Scopus, and Cochrane databases by using appropriate Medical Subject Headings terms covering the period from January 1993 to December 2013. Additional publications from hand-searching and reference section of each relevant article enriched the article list. The LOE of each article was assessed according to guidelines provided by the Oxford Centre of Evidence-Based Medicine. Quality assessment of the observational studies was executed by using the Newcastle-Ottawa scale.
  
  
  RESULTS
  Fifty-one relevant publications were included in this review. There were 2 high-level cohort studies (LOE 2), 8 case series (LOE 4), and 41 case reports (LOE 5). The vast majority of the treated teeth in those publications showed resolution of clinical signs, symptoms, and periapical radiolucencies at follow-up period. Furthermore, the majority of treated teeth presented further increase in root length and root wall thickness and apical closure at the follow-up period. However, because of lack of sufficient high-level evidence it was not possible to answer totally the review question and determine definitely the outcome of regenerative endodontic therapy.
  
  
  CONCLUSIONS
  The lack of adequate high-level studies that could possibly strengthen the satisfactory current data and allow practicing more evidence-based dentistry constitutes a significant knowledge gap in the endodontic literature. However, the current best available evidence undeniably allows clinicians to provide this treatment modality safely to patients.
authors: Department of Endodontics, Dental School, University of Athens, Athens, Greece. Electronic address: ekontak@dent.uoa.gr.
authors: Evangelos G
authors: EG
authors: Kontakiotis
authors: Department of Endodontics, Dental School, University of Athens, Athens, Greece.
authors: Christos G
authors: CG
authors: Filippatos
authors: Department of Endodontics, Dental School, University of Athens, Athens, Greece.
authors: Anastasia
authors: A
authors: Agrafioti
mesh_terms: D056624:Apexification / Q000592:standards; D003786:Dental Pulp Cavity / Q000033:anatomy & histology; D055094:Evidence-Based Dentistry / Q000592:standards*; D006801:Humans; D012038:Regeneration / Q000502:physiology; D012390:Root Canal Therapy / Q000592:standards*; D014092:Tooth Root / Q000033:anatomy & histology; D016896:Treatment Outcome
keywords: Level of evidence; outcome; regenerative endodontic therapy; systematic review