Sir, as postgraduate students in endodontics, we have undertaken a review of the paper by Hansrani (BDJ 2015; 219: 481–483) and would like to share some of our observations with your readers.

Given the content of the paper, the use of the word 'overview' in the title is not justified as it is more of a personal, discursive exercise undertaken by the author. The notable omissions in the paper are the myriad of factors that affect radiographic interpretation, ranging from observer bias to the location of the periapical lesion in the arch and involvement, or otherwise, of the bony cortical plate. Newer, three-dimensional imaging, such as cone beam computed tomography, was not mentioned at all.

Many of the author's statements are as a result of misinterpretation of, and based on, dated literature. There is no mention of the causes of 'failure' that may, for example, be due to extra-radicular or intra-radicular infection. There is also a complete absence of reference to apical surgery and extraction as treatment options for 'failure' cases apart from these being used as criteria to denote 'failure'.

The author failed to adequately define the criteria used to determine treatment outcome; instead, he compounded the deficiency by misquoting the European Society of Endodontology guidelines.1 In fact, these guidelines divided outcome into 'favourable', 'unfavourable' and 'uncertain' as well as an 'exception' category for periapical scars.

Recent outcome studies, for example, Ng et al.2 reported on factors associated with endodontic 'success' and 'survival'. This seminal research is not referenced by the author and if enlightened, perhaps the author would not have given credence to the outdated and discredited theory of 'anachoresis'.

The relative importance of thorough canal preparation, effective irrigation, complete obturation and a good coronal seal are poorly addressed and mislead the readers into thinking that obturation is of no significance. Both Klevant and Eggink3 and Ray and Trope4 were misquoted. Supported by more recent literature (eg Ng et al.2), the evidence points to a combination of high technical quality root canal treatment, as exemplified by good quality obturation, and a good coronal seal, as major contributory factors to 'success'.

In conclusion, we feel that this article grossly misrepresented the topic of radiographic evaluation of 'root fillings'.