Comments about the appraisal of systematic reviews in restorative dentistry

Comments about the appraisal of systematic reviews in restorative dentistry

Dear respectable Advisory Editors and readers:

The publication by Sarkis-Onofre et al.¹ “Systematic reviews in restorative dentistry: discussing relevant aspects,” in the Journal of Esthetic and Restorative Dentistry in the May 2019 issue was read with great and particular interest. This well-written overview of reviews or systematic review of systematic reviews stated that “This study was not registered in PROSPERO” since PROSPERO indicates that “Reviews of methodological issues need to contain at least one outcome of direct patient or clinical relevance in order to be included in PROSPERO.” Interestingly, despite the fact that the above referenced tertiary study falls in the PROSPERO's review of reviews category, it was neglected to being classified as such. Additionally, if PROSPERO was not an option, the a priori protocol could have been easily registered in another repository. Therefore, the authors' arguments not to register their protocol in PROSPERO are not valid.

Moreover, the authors¹ mentioned that the previous version of their review² has a protocol available upon request. However, their first paper², which is in a Brazilian University Magazine printed in Portuguese language, does not support the updated version of the review properly since their first version does not consider any protocol in the text.

Their critical appraisal using AMSTAR-2 appears in Table 2. Five out of the 16 included review studies in their review of reviews, had between one to four AMSTAR-2 items referred as “Authors reported different information by e-mail however, it was not found in the article.” This reporting method may not be the most scholarly or safest to present their findings, especially when the authors of their included review studies kindly accepted to provide further clarification about their methodology.

Particularly, the first author of Afrashtehfar et al.³ “Failure rate of single-unit restorations on posterior vital teeth: a systematic review” regretted the online communication with their corresponding author when he was requested to provide further information. Perhaps Sarkis-Onofre et al. should have dedicated more time to conduct an adequate assessment⁴. For example, their unfavorable categorization of the AMSTAR-2 items 4, 7, and 16 for Afrashtehfar et al.³ may be mistaken. A comprehensive literature search (item 4) can be considered in the former paper³ since it searched for published papers for over 20 years with no language restriction, using four electronic databases (including Embase and Medline via Ovid) and displaying each search strategy in the Appendix section. Additionally, the review hand searched eight journals and also screened manually in the reference list of all identified relevant primary studies and related secondary studies³. Next, the list of excluded primary studies and justifications (item 7) were provided in Supplemental Table 6 (i.e., full-text excluded articles and reasons for exclusion). Regarding any potential sources of conflict (item 16), it is well-stated on the first page of the review that this study was “Supported in part by a Knowledge Transfer Grant from the Network for Oral and Bone Health Research.” Additionally, there is a section at the end of the paper for Acknowledgements where librarians and statisticians were thanked for their consultancy³.

Moreover, the search and eligibility criteria for Sarkis-Onofre et al.¹ were systematic reviews that met PRISMA-P, including adults over 18 years of age with direct composite resin restoration in posterior teeth compared with other materials or techniques used in posterior teeth regardless of the outcome up to October 15^th, 2017. However, some articles that fully suited their inclusion criteria were not included. For example, Afrashtehfar et al.⁵ “Failure of single-unit restorations on root filled posterior teeth: a systematic review” was not included despite being available from November 21^st, 2016. Therefore, their search strategy and their search conduct (including the elimination of duplicates)⁶, as well as screening⁷, raise some serious methodological concerns⁸.

Their overview of reviews has a collaboration with well-known evidence-based medicine experts from Canada, Tricco and Moher⁹, which usually rely on the talent from their research team for screening and assessing the literature.

After a brief analysis, this letter encourages the improvement of future synthesis of studies including their quality assessment to:

Data availability