Root canal master apical file size: is bigger better?



There are three processes to root canal treatment, cleaning, shaping and filing the root canal. There is however considerable debate to how each of these elements should be achieved. The aim of this review was to determine if this is an optimal apical enlargement that leads to optimal healing in teeth requiring root canal treatment.


Searches were conducted in PubMed/Medline, Embase, and Cochrane Library, supplemented by searches of the bibliographies of relevant article and textbooks. In vivo studies with follow up of 12-months or greater comparing different size apical preparation were considered. Two reviewers carried out study selection independently.


  • 4 studies involving a total of 840 patients were included.
  • Follow up ranged for 12 – 60 months
  • A qualitative summary of the studies is presented.
  • 1 study reported a significant difference in favour of a larger apical preparation with a second one reporting a decrease. The other two reported no differences.


The authors concluded

The results of the systematic review confirmed that more evidence-based research in this area is needed. With the limited information available, the best current available clinical evidence suggests that for patients with necrotic pulps and periapical lesions, enlargement of the apical size would result in an increased healing outcome in terms of clinical and radiographic evaluations.


This review has a good search strategy but was only able to include one randomised trial which we have discussed in a previous blog ( Dental Elf 17th Oct- 2012) .  The included studies are heterogeneous and are subject to a range of biases so the findings need to be interpreted with caution.


Aminoshariae A, Kulild JC. Master apical file size – smaller or larger: a systematic review of healing outcomes. Int Endod J. 2014 Aug 12. doi: 10.1111/iej.12370. [Epub ahead of print] PubMed PMID: 25113106.

Dental Elf -17th Oct-2013 – Apical preparation for root canal treatment, how much is needed?

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