METHODS: Extracted human primary maxillary second molars (n = 57) were scanned using micro-computed tomography and reconstructed to produce three-dimensional models. Each root canal system was analysed qualitatively according to Vertucci's classification.
RESULTS: 22.8% (n = 13) of the sample presented with the fusion of the disto-buccal and palatal roots; of these, Type V was the most prevalent classification. For teeth with three separate roots (n = 44), the most common root canal type was Type 1 for the palatal canal (100%) and disto-buccal canal (77.3%) and Type V for the mesio-buccal canal (36.4%). Overall, 7% (n = 4) of mesio-buccal canals were 'unclassifiable'.
CONCLUSION: The root canal systems of primary maxillary second molars were not only complex but had a range of configurations that may contribute to unfavourable clinical outcomes after endodontic treatment.
METHODS: This systematic review was undertaken following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The protocol has been registered with the International Prospective Register of Systematic Reviews (number CRD42019127021). A comprehensive literature search was performed by 2 independent reviewers using a selected search strategy in 2 electronic databases (PubMed and Scopus) until January 28, 2019. A further search was performed manually in endodontic journals. Studies investigating or comparing at least 1 shaping property resulting from root canal instrumentation with a glide path or preflaring in human extracted teeth or clinical studies were included.
RESULTS: The literature shows that the definition of glide path and preflaring procedures remains controversial, which requires an elaboration in the American Association of Endodontists' Glossary of Endodontic Terms. After the removal of irrelevant and duplicated articles, 98 articles were included. The impact of glide path preparation and preflaring on working length determination, apical file size determination, canal transportation, separation of endodontic files, shaping time, dentinal microcrack formation, and extrusion of debris was discussed. Because of heterogeneity among the included studies, quantitative synthesis was not performed for most of the parameters.
CONCLUSIONS: An evidence-based guideline is needed to define and correlate the basic concepts and current applications of each step of contemporary advancements in root canal instruments. Glide path preparation reduces the risk of debris extrusion, has no influence on the incidence of dentinal crack formation, and improves the preservation of the original canal anatomy. The creation of a glide path may have no impact on Reciproc files (VDW, Munich, Germany) in reaching the full working length. Preflaring increases the accuracy of working length determination. Further randomized clinical trials are required to evaluate the effect of a glide path and preflaring on root canal treatment outcomes.
METHOD: An electronic search was performed on Web of science, PubMed, and Scopus. Micro-CT journal studies investigated the root and canal anatomy of permanent double-rooted mandibular first molars were included. Data on study characteristics, objectives of interest, specifications of the studies, and micro-CT specifications were extracted. Risk of bias assessment (ROB) of the included studies was performed using Anatomical Quality Assessment (AQUA) tool. The extracted data were presented in tables and figures to present and synthesise the results. A meta-analysis was performed for the studies related to the prevalence of Vertucci's canal configurations, middle mesial canal (MMC) configurations, and Fan's isthmus types.
RESULTS: Amongst 1358 identified studies, thirty met the inclusion criteria. In terms of the objectives, the selected studies showed high anatomical variability in mandibular first molars. Twenty-two (73%), 25 (83%), and 12 (40%) of the studies reported the population/ethnicity, micro-CT specifications, and ethical approval, respectively. 28 (93%) studies did not disclose the method of sample size estimation. In only 6 (20%) of the studies, the authors had calibrated the assessment approaches. Mostly, a potential ROB was reported in domain 1 (objective(s) and subject characteristics) and domain 3 (methodology characterization). Whilst, low risk was reported in domains 2 (study design), 4 (descriptive anatomy), and 5 (reporting of results). The overall ROB was reported to be ''moderate'' in the vast majority of the studies (27/30). Meta-analysis results showed high levels of heterogeneity among the studies related to MMCs (I2 = 86%) and Fan's isthmus (I2 = 87%). As for the root canal configuration, pooled prevalence showed that Vertucci type IV and type I were the most prevalent in mesial and distal root canals, respectively.
CONCLUSION: Based on moderate risk of bias level of evidence, micro-CT studies have shown wide range of qualitative and quantitative data presentations of the roots and canals in mandibular first molars. Protocol and registration. The protocol of this systematic review was prospectively registered in the Open Science Framework database ( https://osf.io ) on 2022-06-20 with the registration number 10.17605/OSF.IO/EZP7K.
METHODS: The survey was conducted using physical and online presentation modes in two phases. Phase 1; PowerPoint presentation (PPT), describing the most used classification system (Vertucci et al. 1974) and its supplementary types and Ahmed et al. (2017) classification. A single presenter delivered the PPT to participants, using either a projector in an auditorium/seminar hall (face-to-face) or an online platform (zoom meeting software). Phase 2 involved determining the students' responses. A questionnaire was distributed amongst the participants after the lecture and collected for analysis. Fisher's exact test was used to analyze the data statistically, and the significance level was set at 0.05 (p dental students, and interns in India agreed that Ahmed et al. classification system is more practical and accurate for classifying the root and canal morphology.
AIM: To conduct an umbrella review to determine whether there is an association between diabetes and the outcome of root canal treatment.
DATA SOURCE: The protocol of the review was developed and registered in the PROSPERO database (CRD42019141684). Four electronic databases (PubMed, EBSCHOhost, Cochrane and Scopus databases) were used to perform a literature search until July 2019.
STUDY ELIGIBILITY CRITERIA, PARTICIPANTS AND INTERVENTIONS: Systematic reviews with or without meta-analyses published in English assessing any outcomes of root canal treatment comparing diabetic and nondiabetic patients were included. Two reviewers were involved independently in study selection, data extraction and appraising the reviews that were included. Disagreements were resolved with the help of a third reviewer.
STUDY APPRAISAL AND SYNTHESIS METHODS: The quality of the reviews was assessed using the AMSTAR tool (A measurement tool to assess systematic reviews), with 11 items. Each AMSTAR item was given a score of 1 if the criterion was met, or 0 if the criterion was not met or the information was unclear.
RESULTS: Four systematic reviews were included. The AMSTAR score for the reviews ranged from 5 to 7, out of a maximum score of 11, and all the systematic reviews were classified as 'medium' quality.
LIMITATIONS: Only two systematic reviews included a meta-analysis. Only systematic reviews published in English were included.
CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS: Diabetes mellitus is associated with the outcome of root canal treatment and can be considered as a preoperative prognostic factor.