METHODOLOGY: Systematic reviews with NMAs within the specialty of Endodontics published in English were identified from the PubMed, EbBSCOhost and SCOPUS databases from inception to July 2021. Two reviewers were involved independently in the selection of the reviews, data extraction, methodological quality assessment and overall confidence rating. Disagreements were resolved by discussion between the reviewers to achieve consensus; if disagreements persisted, a third reviewer made the final decision. The methodological quality of the included NMAs was appraised using the AMSTAR 2 checklist, which contains 16 items. The reviewers scored each item - 'Yes' - when the item was fully addressed, 'Partial Yes' - when the item was not fully addressed, or 'No' - when the item was not addressed. The overall confidence in the results of each review was classified as 'High', 'Moderate', 'Low' or 'Critically low' based on the criteria reported by the AMSTAR 2 developers.

RESULTS: Twelve systematic reviews with NMAs were included. All the NMAs adequately reported Item 1 ("Did the research questions and inclusion criteria for the review include the components of PICO?"), Item 8 ("Did the review authors describe the included studies in adequate detail?"), Item 9 ("Did the review authors use a satisfactory technique for assessing the risk of bias (RoB) in individual studies that were included in the review?") and Item 16 ("Did the review authors report any potential sources of conflict of interest, including any funding they received for conducting the review?") , whereas only one NMA reported Item 10 adequately ("Did the review authors report on the sources of funding for the studies included in the review?"). The overall confidence in the results of eight reviews was categorised as "Critically low", one review was "Low", two reviews were "Moderate" and one review was "High".

METHODOLOGY: This study was designed as a parallel, double blind, randomized controlled trial where symptomatic mature permanent teeth with carious pulp exposure meeting the inclusion criteria were randomly treated with full pulpotomy using one of 3 calcium silicate-based materials (ProRoot MTA, Biodentine and TotalFill). Full pulpotomy was performed, and haemostasis was achieved via a cotton pellet moistened with 2.5% NaOCl. A 3-mm layer of the calcium silicate-based material was randomly placed as the pulpotomy agent through a block randomization process followed by a resin-based composite restoration. Postoperative periapical radiograph was taken. Clinical and radiographic evaluation were completed after 6 months and 1 year. The patient and evaluator were blinded to the type of materials used. Pain levels were scored preoperatively and 7 days after treatment. Effect of potential prognosis factors including gender, age, diagnosis, bleeding time and type of caries were also analysed.

RESULTS: One hundred and sixty-four teeth in 146 patients received full pulpotomy and were randomly assigned to either the tested or control material through block randomization technique (50 MTA, 50 Biodentine and 64 TotalFill). The age ranged from 10 to 70 years. The diagnosis was irreversible pulpitis in 112 teeth (72%) and reversible pulpitis in 28 teeth (28%). The majority of patients presented with severe pain, during the first week 96.9% reported complete relief of pain or mild pain. Four cases had immediate failure. At 6 months the overall success rate was 92.2%, over 1 year 156/164 teeth attended follow-up with 12 failures (2 restorative failures and 10 endodontic failures), the overall success of pulpotomy at 1 year was 92.3% (144/156); 91.8% in MTA, 93.3% in Biodentine and 91.9% in TotalFill with no significant difference amongst the groups and no side effects observed. No significant association was evident between outcome and the investigated variables.

DATA SOURCES: Literature searches of PubMed, Scopus, Cochrane Library, Trip Database, Web of Science and Open Grey databases were conducted from their inception until November 2018 with no language restriction. Hand searching of most likely relevant journals was performed. The review followed the PRISMA guidelines.

STUDY ELIGIBILITY CRITERIA, PARTICIPANTS AND INTERVENTIONS: Studies that compared pre-clinical endodontic training using extracted teeth and artificial teeth were included.

STUDY APPRAISAL AND SYNTHESIS METHODS: The quality of included studies was appraised by Joanna Briggs Institute Critical Appraisal tools. The findings were tabulated and summarized according to their outcomes with distinct narrative syntheses.

RESULTS: Five studies were included. The component studies included 359 operators in total, mainly consisting of undergraduate students (97%, n = 349) and 10 endodontists (3%). Forty-seven per cent (n = 170) operated on artificial teeth only, whilst 19% (n = 67) worked primarily on extracted teeth, with the final treatment outcome being evaluated by independent observers using objective criteria. Operators in two studies (34%, n = 122) used both artificial teeth and ET and compared their experiences in surveys. Regarding technical outcomes, no significant differences between training with artificial teeth and extracted teeth were found, but the performance tended to be better in artificial teeth than extracted teeth. Operators trained solely on artificial teeth appeared to be adequately educated for subsequent root canal treatment (RCT) in the clinical setting.

LIMITATIONS: Due to the scarcity of research on the topic overall, and the methodological variation between the studies, it was not possible to perform a quantitative analysis (meta-analysis).