# A practical transportation of Apical Foramen by Different NiTi Alloy Systems: A Systematic Review
## 3 Results and Discussion
### Limitations  
The main limitation of this article is its reliance on in vitro studies. Although in vitro studies provide valuable insights into the effects of different endodontic instruments, they may not fully reflect the complexities and variations found in clinical settings. Factors such as the presence of surrounding tissues, biological responses, and patient-specific variables cannot be accurately replicated in an in vitro environment. Therefore, the findings of this review should be extrapolated to clinical practice with caution, and further research involving clinical trials is needed to validate the results.  
The main limitation of the in vitro studies considered in this review is the high risk of bias. The absence of a blinded investigator and the lack of a methodology involving random sequence generation introduce potential selection bias. Blinding is important in order to minimize the influence of bias in the assessment of outcomes, and random sequence generation is crucial for ensuring the unbiased allocation of interventions. The absence of these key elements in the included studies raises concerns regarding the internal validity of their findings.  
Another limitation is the lack of standardization across the studies. Each study evaluated different root canals with varying diameters and curvatures, leading to diverse results. The impossibility of testing both instrument systems in the same root canal hampers direct comparisons and makes it challenging to draw definitive conclusions. The variations in the anatomy of the root canals and the lack of standardization in the experimental conditions introduced potential confounding factors that may have influenced the observed outcomes.  
Furthermore, a significant proportion of the literature is focused primarily on evaluating canal transportation rather than apical transportation. Only a few studies have been performed in which apical transportation was specifically investigated, and different types of NiTi alloy compared. This limited availability of studies directly examining apical transportation with the use of different NiTi alloys restricts the depth and breadth of evidence on this specific aspect. Therefore, further research is needed to address these limitations and to provide more comprehensive insights into the effects of different NiTi alloys on apical transportation.  
One strong point of this article is its rigorous adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. By following a well-defined protocol and conducting a comprehensive literature search, the authors have ensured transparency and reproducibility in their review process. The inclusion of a registered protocol number further enhances the credibility of the study. Additionally, the involvement of two independent researchers and consultation with a senior researcher for discrepancies adds to the robustness of the study. These methodological aspects increase the reliability of the findings and strengthen the overall quality of this systematic review.