We are pleased to respond to the letter from Stoelinga regarding our recent systematic review and we appreciate the opportunity to address the concerns and criticisms he raised.

Stoelinga states that he is taken back by the fact that only two of 168 reviewed papers contributed to the existing knowledge on the recurrence tendency of keratocystic odontogenic tumour (KCOT). Although we share his concerns, we need to stress that any systematic review tries to solely identify high-quality evidence and the number of papers finally reviewed results from established criteria for paper selection. Since Stoelinga did not raise any objections to the criteria established for the selection process in our review, we do not understand why he objects to the number of papers finally selected.

We acknowledge that the retrospective nature of the papers reviewed does not allow some pertinent information to be obtained such as ascertaining the diagnosis. Stoelinga correctly states that many odontogenic keratocysts (OKC) were previously treated as regular cysts. Indeed, the vast majority of published papers regarding treatment for OKC are of a retrospective nature and claim a uniform treatment protocol as the diagnosis was not secured before surgery in most cases. But even after re-definition of OKC to odontogenic tumour, most researchers do not cover this aspect in their studies and no randomized controlled trials have been conducted. It may present a bias; however, it was explicitly emphasized in our paper that none of the articles finally accepted for review were among the first four levels of evidence. The point raised by Stoelinga, alas, stands for further proof of inadequacy of research in this field.

Papers dated before 2005 contemplated the aspect of form of keratinization of OKC: parakeratinized OKC (currently KCOT) was considered as more aggressive than the orthokeratinized variant. Since 2005, these two lesions have been regarded as different entities. In order to obtain the best scientific proof in our systematic review, we decided not only to analyse articles published from 2005 onwards, but also those published before 2005, yet strictly distinguishing the orthokeratinizing from the parakeratinizing type of OKC and pooling the data into separate sets. In 2001, however, in a paper by Stoelinga in which orthokeratinizing cysts are separately discussed, the data on treatment modalities and the recurrence rate of both types of OKCs are pooled into one set and it is impossible to extract the data on recurrence rates of the parakeratinizing type of OKC with reference to the treatment method. This was the reason for exclusion of this paper from the final analysis in our systematic review.

Certainly, the mechanisms of KCOT recurrence described by Stoelinga are of great relevance, and the essence of relapse development plays a vital role in the selection of the treatment method. Nevertheless, we would like to emphasize that our systematic review attempted exclusively to determine the recurrence rate of KCOT following treatment and the volume of the article did not allow discussion of the mechanism of tumour relapse in such a meticulous way. We do not agree with Stoelinga’s assertion that the research question in our systematic review should have included the reason for recurrence. This issue could only be discussed but not treated as a variable that could be ‘collected’ and ‘analysed’ in a systematic review.

Nowhere in the systematic review is it even suggested that acquired data stands for ultimate results and should be looked at as being ‘cemented in stone’. Instead, we specifically emphasized that our review failed to identify any reliable evidence on recurrence rates in relation to treatment modalities for KCOT, and that presented results of the recurrence rates for some treatment methods are based on a small number of cases. To address this issue even more distinctly, we decided to present 95% confidence intervals. We are also convinced that future authors referring to our paper will certainly read the article in its entirety, not only the abstract. Even so, the abstract to our paper emphatically indicates that no high-quality evidence was obtained to evaluate the recurrence rates related to treatment modalities of KCOT.

To address the concerns of Stoelinga about mistakenly using his name with reference to paper no. 128, we need to emphasize that the bibliographical data on that paper is absolutely correct. Worrall is the author of the article entitled Recurrent odontogenic keratocyst within the temporalis muscle , which was published in volume 30 of the British Journal of Oral and Maxillofacial Surgery on pages 59–62 (reference no. 142 in our paper), whereas reference no. 128 is Stoelinga’s comment on this article on pages 277–8 in the same volume of this journal. The Medline record does not contain the note ‘Comment on’ at the beginning of the title of Stoelinga’s letter, and all references in our systematic review were cited strictly according to Medline records. At this point, we would like to draw Stoelinga’s attention to Kaczmarzyk being a totally different author from Kaczmarzyc, as he erroneously named the first author of the discussed systematic review in his letter.

In conclusion, we are aware that our systematic review includes some controversies and exposes the weakness of literature evidence in the issue of KCOT treatment. However, it calls for future investigations to be carried out in a more credible fashion and the debate that has thus been ignited is paving the way for pushing forward the boundary of our understanding of its course, diagnosis ascertainment, the essence of recurrence development and approach to treatment strategies. Therefore, we are truly grateful to Stoelinga for giving us the opportunity to discuss these vital aspects.