Present status and future directions - Minimal endodontic access cavities.

In the last decades, the move of medicine towards minimally invasive treatments is notorious and scientifically grounded. As dentistry naturally follows in its footsteps, minimal access preparation have also becume a trend topic in the endodontic field. This procedure aims to maximize preservation of dentine tissue backed up by the idea that this is an effective way to reduce the incidence of post-treatment tooth fracture. However, with the assessment of the body of evidence on this topic, it is possible to observe some key points (a) the demand for nomenclature standardization, (b) the requirement of specific tools such as ultra-flexible instruments, visual magnification, superior illumination, and three-dimensional imaging technology, (c) minimally invasive treatment does not seem to affect orifice location and mechanical preparation when using adequate armamentarium, but it (d) may impair adequate canal cleaning, disinfection and filling procedures, and also (e) it displays contradictory results regarding the ability to increase the tooth strengthen compared to the traditional access cavity. In spite of that, it is undeniable that methodological flaws of some benchtop studies using extracted teeth may be responsible for the conflicting data, thus triggering the need for more sophisticated devices/facilities and specifically designed research in an attempt to make clear the role of the access size/design on long-term teeth survival. Moreover, it is inevitable that a clinical approach such as minimal endodontic access cavities that demands complex tools and skilled and experienced operators bring to the fore doubts on its educational impact mainly when confronted with the conflicting scientific output, ultimately provoking a cost-benefit analysis of its implementation as a routine technique. In addition, this review discusses the ongoing scientific and clinical status of minimally invasive access cavities aiming to input an in-depth and unbiased view over the rationale behind them, uncovering not only the related conceptual and scientific flaws but also outlining future directions for research and clinical practices. The conclusions attempt to skip from passionate disputes highlighting the current body of evidence as weak and incomplete to guide decision making, demanding the development of a close-to-in situ laboratory model or a large and well-controlled clinical trial to solve this matter.

Current strategies for conservative endodontic access cavity preparation techniques-systematic review, meta-analysis, and decision-making protocol.

OBJECTIVES: To assess related studies and discuss the clinical implications of endodontic access cavity (AC) designs. MATERIALS AND METHODS: A systematic review of studies comparing the fracture resistance and/or endodontic outcomes between different AC designs was conducted in two electronic search databases (PubMed and Web of Science) following the PRISMA guidelines. Study selection, data extraction, and quality assessment were performed. Meta-analyses were undertaken for fracture resistance and root canal detection, with the level of significance set at 0.05 (P = 0.05). RESULTS: A total of 33 articles were included in this systematic review. The global evaluation of the risk of bias in the included studies was assessed as moderate, and the level of evidence was rated as low. Four types of AC designs were categorized: traditional (TradAC), conservative (ConsAC), ultraconservative (UltraAC), and truss (TrussAC). Their impact on fracture resistance, cleaning/disinfection, procedural errors, root canal detection, treatment time, apical debris extrusion, and root canal filling was discussed. Meta-analysis showed that compared to TradAC, (i) there is a significant higher fracture resistance of teeth with ConsAC, TrussAC, or ConsAC/TrussAC when all marginal ridges are preserved (P < 0.05), (ii) there is no significant effect of the type of AC on the fracture resistance of teeth when one or two marginal ridges are lost (P > 0.05), and (iii) there is a significantly higher risk of undetected canals with ConsAC if not assisted by dental operating microscope and ultrasonic troughing (P < 0.05). CONCLUSIONS: Decreasing the AC extent does not necessarily present mechanical and biological advantages especially when one or more surfaces of the tooth structure are lost. To date, the evidence available does not support the application of TrussAC. UltraAC might be applied in limited occasions. CLINICAL RELEVANCE: Maintaining the extent of AC design as small as practical without jeopardizing the root canal treatment quality remains a pragmatic recommendation. Different criteria can guide the practitioner for the optimal extent of AC outline form which varies from case to case.

Current status on minimal access cavity preparations: a critical analysis and a proposal for a universal nomenclature.

In the last decade, several access cavity designs involveing minimal removal of tooth tissue have been described for gaining entry to pulp chambers during root canal treatment. The premise behind this concept assumes that maximum preservation of as much of the pulp chamber roof as possible during access preparation would maintain the fracture resistance of teeth following root canal treatment. However, the smaller the access cavity, the more difficult it may be to visualize and debride the pulp chamber as well as locate, shape, clean and fill the canals. At the same time, a small access cavity may increase the risk of iatrogenic complications as a result of poor visibility, which may have an impact on treatment outcome. This study aimed to critically analyse the literature on minimal access cavity preparations, propose new nomenclature based on self-explanatory abbreviations and highlight the areas in which more research is required. The search was conducted without restrictions using specifics terms and descriptors in four databases. A complementary screening of the references within the selected studies, as well as a manual search in the highest impact journals in endodontics, namely International Endodontic Journal and Journal of Endodontics, was also performed. The initial search retrieved 1831 publications. The titles and abstracts of these papers were reviewed, and the full text of 94 studies was assessed. Finally, a total of 28 studies were identified as evaluating the influence of minimally invasive access cavity designs on the fracture resistance of teeth and on the different stages of root canal treatment (orifice location, canal shaping, canal cleaning, canal filling and retreatment). Overall, the studies had major methodological drawbacks and reported inadequate and/or inconclusive results on the utility of minimally invasive access preparations. Furthermore, they offered limited scientific evidence to support the use of minimally invasive access cavities to improve the outcome of root canal treatment and retreatment; they also provided little evidence that they preserved the fracture resistance of root filled teeth to a greater extent than traditional access cavity preparations. It was concluded that at present, there is a lack of supporting evidence for the introduction of minimally invasive access cavity preparation into routine clinical practice and/or training of undergraduate and postgraduate students.

Influence of minimally invasive access cavities on load capacity of root-canal-treated teeth: A systematic review and meta-analysis.

This systematic review (PROSPERO-CRD42020147333) aimed to compare the effects of conservative, ultraconservative and truss access cavities with traditional access cavities on the load capacity of root-canal-treated teeth. Online databases were searched until December 2021, and 25 ex vivo studies in which the effects of different access cavities on load capacity of permanent teeth had been investigated were included. Quality assessment was completed using a modified risk of bias tool for in vitro studies adapted from previous studies. Meta-analysis was performed using the maximum-likelihood-based random-effects model with similar groups. Conservative access cavities significantly improved the load capacity of maxillary premolars (p < 0.01 [-1.32, -0.028]) and molars (p < 0.05 [-0.89, -0.02]) compared to traditional access cavities. Additionally, truss access cavities significantly improved the load capacity of mandibular molars with (p < 0.05, [-1.18, -0.02]) mesio-occluso-distal cavity preparations. Higher levels of evidence are needed to determine the long-term implications of minimal preparations for treatment outcomes.

Management of Pulp Canal Obliteration in Mandibular Incisors with Guided Endodontic Treatment: A Case Report.

Successful management of mandibular incisors with pulp canal obliteration using guided endodontics is described, for the first time in Iran. A 58-year-old man was referred for root canal treatment of teeth #24, #25 and #26. Upon radiographic examination, partial obliteration of the root canal system was detected. Cone-beam computed tomography (CBCT) was requested to enhance the diagnosis and detection of root canals. Next, a 3-dimensional (3D) guide was designed and printed to aid in localization and access to the root canal system with minimal destruction of the tooth structure. With the use of a targeted 3D guide, a conservative access cavity was prepared to avoid unnecessary removal of tooth structure. The teeth were successfully treated endodontically. Obtained results revealed that the technique can be effective and predictable for the management of calcified canals.

Access Cavity Preparations: Classification and Literature Review of Traditional and Minimally Invasive Endodontic Access Cavity Designs.

INTRODUCTION: Several endodontic access cavity designs have been proposed in the past decade to access the root canal space in a minimally invasive manner. The rationale for this approach was derived from the assumption that preserving more tooth structure during access preparation will improve the tooth's resistance to fracture and its long-term survivability. However, is this assumption valid? Also, can this approach compromise other treatment-related aspects? METHODS: We conducted a literature review using 4 online databases and classified the access cavity designs presented in each article according to our proposed classification. RESULTS: Through the literature search, we identified 49 articles that evaluated the effect of the access cavity design on 11 different treatment parameters. The majority of the studies failed to demonstrate clear benefits of the minimally invasive access designs, whereas others raised concerns regarding the ability to adequately disinfect, fill, and restore teeth with a minimally invasive access cavity design. CONCLUSION: Minimally invasive access cavity designs present more risk than benefit on the outcome of endodontic treatment. Clinicians should reconsider the application of a minimally invasive access cavity for routine endodontics and cautiously apply it in selected cases when the proper armamentarium is available.