Sir, we are compelled to write to express our dismay at the content of the paper by Hansrani on assessing root canal fillings.

Nearly all the views expressed in the paper are personal opinions, not based on sound scientific evidence or supported by careful and critical analysis of the literature. A principal worry is the constant use of unreferenced or indeed inappropriately referenced statements, which are misleading and not evidence-based. We could provide a line-by-line critique and multiple examples of the deficiencies of the paper but we have selected just a few.

The title does not reflect the contents; purporting to be an overview on assessing root fillings on a radiograph, it is one person's philosophical discourse on the science and practice of endodontics. The interchangeable use of the terms 'periradicular periodontitis', 'periapical periodontitis' and 'apical periodontitis' shows ignorance of terminology and is only one of many examples of sloppiness.

In the opening paragraph, it is claimed that the European Society of Endodontology (ESE) guidelines1 state that 'radiographs should show the root apex with preferably at least 2-3 mm of the periapical region clearly identifiable.' In an act of self-contradiction, the author then included, amongst the 11-year-old reprinted illustrations, a radiograph (Fig. 2) that failed to meet this requirement and of 'unacceptable' quality if rated according to published guidelines;2,3,4 the other two accompanying radiographic images (Figs 1 and 3) are only just about 'diagnostically acceptable'.

Re-stating the ESE's criteria defining an unfavourable outcome,1 the author is economical with accuracy by conveniently not including the 'Exception: An extensive radiological lesion may heal but leave a locally visible, irregularly mineralised area. This defect may be scar tissue formation rather than a sign of persisting apical periodontitis. The tooth should continue to be assessed.' Compounding the sin of omission, the author listed in the next paragraph the unrecognised criteria defining 'failure', which is not part of the ESE guidelines1 and not one of the three outcome categories ('favourable', 'uncertain' and 'unfavourable').

The inaccurate claim that 'radiographs of single rooted teeth can be easier to interpret and understand than those of maxillary permanent molar teeth' discounted mandibular molars. The one reference5 cited on the microbiota of the root canal system overlooks the more recent, and abundance of, studies using newer, culture-independent techniques.

To trot out Dubrow6 as a reference in order to claim that canal obturation is not required is to live in the past as the paper made reference to silver points, an obsolete root filling material already consigned to history. In addition, to further justify this contention Klevant and Eggink7 was inappropriately used as in their paper healing was improved in the 'root filled' cohort over the 'dressed' controls.

The statement that the use of NiTi 'leads to improved success rates in endodontics' is unreferenced and presented as fact when, at present, there is a lack of a convincing body of evidence to uphold this claim. The author continuing to live in the past is further exemplified by the claim that 'obturation prevents entry of microorganisms into the root canal system from the oral cavity or via the blood system'. The idea of blood (anachoresis) as a source of infection has been outdated for years.

To claim that 'similar failure rates for teeth with radiographically optimal and suboptimal root fillings suggest RCT is not as technically sensitive as once thought' shows blatant ignorance. Does it mean that the author is happy to receive a sub-optimal root filling? Is the author saying that dental schools no longer need to teach and expect, and clinicians do not need to achieve, high technical quality root fillings? Is the author not aware of, for example, the work of Sjogren et al.,8 Ng et al., as well as the systematic review by Ng et al.?10 They all highlighted technical factors, as measured by radiographic quality of root fillings, as a principal prognostic factor in healing. A strong association between apical periodontitis and root filled teeth, and between periapical health and the technical quality of the root canal treatment, was further confirmed in a recent paper11 in the BDJ. In addition, papers contrary to the views of Ray and Trope12 and the many deficiencies of the study by Tickle et al.13 have been pointed out in letters14,15,16 to the BDJ.

We think this paper by Hansrani should have been rejected. It is unfortunate at a time where our medical colleagues are insisting on placing evidence within the context of systematic reviews17 that there is publication space for the opposite.