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(1) The objective of the study is to conduct a comprehensive systematic review of in vitro studies in order to assess the depth to which E. faecalis bacteria penetrate human dentinal tubules after the use of various irrigation solutions. (2) Methods: A literature search of the MEDLINE, Scopus, Cochrane CENTRAL, and Embase databases was conducted, as well as a backward and forward citation search. Two independent reviewers then selected suitable studies based on inclusion and exclusion criteria. Data were extracted and the risk of bias and methodology of the studies were evaluated. (3) Results: Out of a total of 504 papers evaluated following the removal of duplicates, 7 studies met the inclusion criteria and were included in the systematic review. The heterogeneity of the studies made it impossible to perform a meta-analysis. The majority of the studies reported that sodium hypochlorite (NaOCl) and chlorhexidine digluconate (CHX) can affect the penetration depth of E. faecalis suspensions. The studies included in this review possess a moderate to high risk of bias and thus represent moderate evidence that the antimicrobial activity of NaOCl and CHX affects the intra-tubular penetration of bacteria. (4) Conclusions: The evidence indicates that irrigants may affect the bacteria inside human dentinal tubules. Standardized high-quality methods are needed to evaluate bacterial penetration in in vitro studies.

Background: The purpose of this in vitro study was to compare the implant axis’ spatial position and orientation by using laboratory scanner versus intra-oral scanner with three different scan abutments. Methods: A 3D model was printed with an internal hex implant analog in the place of teeth 35#. Three standard scan abutments were used: MIS (two-piece titanium), AB (two-piece PEEK and titanium base) and ZZ (one-piece PEEK). Each scan abutment was scanned 30 times by TRIOS E3 (laboratory scanner) and 30 times by Omnicam (intra-oral scanner). For each scan, an STL (stereolithography) file was created, and the spatial characterization of each scan abutment was measured in the X, Y, Z coordinates, and rotational and longitudinal angles. The comparison between all the scans was conducted by superimposition of the STL files, using a 3D software. A t-test and Wilcoxon signed-rank test were used. (p < 0.05) Results: Only the MIS scan abutment showed no statistical difference in the X and Z axes. (p < 0.05). All other scan abutments showed a statistical difference in all axes. The rotational angle of the AB scan abutment was twice the angle of the MIS and ZZ scan abutments. Conclusions: All three scan abutments showed a rotational deviation of the implant axis between the laboratory scanner and the intra-oral scanner. The AB scan abutment showed the greatest deviation (1.04 degrees) while the other two abutments showed deviations of about half a degree in relation to the laboratory scan abutment. There is a need for further studies which will examine the influence of geometry, material, and scan abutment parts on the accuracy of the scan obtained.