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

Abstract

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.

Minimally invasive access cavities: does size really matter?

“…Apart from nomenclature issues, which include more than 20 terms to designate similar cavity designs thus creating obstacles for scholarly communication (Silva et al . 2020), it is always timely to be reminded of the fact that Endodontics is or at least should be a science‐based specialty, which cannot rely on pure deductive reasoning. There are three classical reasons why the clinical decision‐making process should not be guided by extrapolation or ‘common sense’: the hindsight bias, the judgmental overconfidence and our habitual tendency to perceive unreal patterns in random events.…”

“…Silva et al . 2020). Unfortunately, there are no clinical studies available that have followed the healing rate of teeth accessed with a minimally invasive approach, and therefore, no evidence is available to support the claim that conservative access cavities would improve the long‐term survival of root filled teeth.…”

“…From this starting point, the debatable concept of 'the more dentine is preserved, the better the treatment outcome' has been followed religiously by some proponents and influencers in the field of Endodontology, cumulating in extremely conservative approaches popularly known as 'ninja' and 'truss' access. Apart from nomenclature issues, which include more than 20 terms to designate similar cavity designs thus creating obstacles for scholarly communication (Silva et al 2020), it is always timely to be reminded of the fact that Endodontics is or at least should be a science-based specialty, which cannot rely on pure deductive reasoning. There are three classical reasons why the clinical decision-making process should not be guided by extrapolation or 'common sense': the hindsight bias, the judgmental overconfidence and our habitual tendency to perceive unreal patterns in random events.…”

“…As a matter of fact, the negative effects of minimal access cavities related to canal orifice location, and the quality of chemomechanical canal preparation and filling procedures appear to overshadow the perceived benefits (Saygili et al2018, Rover et al2020, Silva et al2020, Vieira et al2020. Moreover, iatrogenic deviations, instrument fractures and tooth discoloration have also been reported as potential consequences of extremely minimal access preparations (Alovisi et al 2018 Marchesan et al2018, Silva et al 2020. Unfortunately, there are no clinical studies available that have followed the healing rate of teeth accessed with a minimally invasive approach, and therefore, no evidence is available to support the claim that conservative access cavities would improve the long-term survival of root filled teeth.…”

Impact of Access Cavity Design on Fracture Resistance of Endodontically Treated Molars: A Systematic Review

“…They divided them into six groups: traditional access cavity (TradAC), conservative access cavity (ConsAC), ultra-conservative access cavity (UltraAC), truss access cavity (TrussAC), caries-driven access cavity (CariesAC), and restorative-driven access cavity (RestoAC). 22 …”