Table 5.

Summary of the limitations reported in the systematic reviews/meta-analyses included (n =20)

Limitations	n (%)
Some studies included in the systematic reviews do not clarify the difference between survival and success.	20 (100.0)
In the studies included in the systematic reviews, the success of endodontic regeneration was defined with different parameters, so there is a difference in the concept of success for the different authors.	16 (80.0)
Studies with small sample sizes were included in some of the systematic reviews	15 (75.0)
Some of the systematic reviews do not follow a methodology protocol for this type of study and do not present a record for this purpose.	13 (65.0)
Amongst the different studies included in the systematic reviews there are different regeneration protocols, some include natural and systematic scaffolds, use of stem cells, or blood clot only. Also, they use different materials in cervical barriers such as Biodentine, MTA, ect.	12 (60.0)
The systematic reviews expose a lack of scientific evidence with methodological rigor and propose to carry out more and better clinical trials.	8 (40.0)
In the evaluation of the risk of bias of the studies, different methodologies were presented in the systematic reviews, which does not allow a standardization of quality.	8 (40.0)
Only publications in English language were included in our review and no grey literature was searched, which may be a limitation in the study selection process.	4 (20.0)
Many studies included in these reviews were uncontrolled longitudinal studies and randomized controlled clinical trials with high levels of bias. There were also systematic reviews of clinical case studies.	2 (10.0)
Some of the clinical trials included in these studies did not report sample size calculations.	2 (10.0)
Systematic reviews where meta-analyzes were carried out argued high methodological heterogeneity in the included studies.	2 (10.0)
Some of these systematic reviews compared animal studies to human studies.	1 (5.0)