# Static Bacterial Leakage in Different Conometric Connections: An In Vitro Study
## 4 Discussion
2011 [3] conducted one of the first studies to demonstrate the passage of microorganisms through microgaps in the Cone-Morse system, shedding light on the failure of cold welding. Even so, it is possible to notice that the Cone-Morse connection presents less bacterial infiltration compared to the classic internal and external hexagon connection systems. According to the same author [3], Morse-Cone connection implants have abutment fixation by frictional locking, and there may be a microgap with irregular characteristics. However, due to the conical interface of the implant, lateral loads are resisted, preventing the loosening of the abutment. Positive or geometric locking, which prevents inclination by shielding the abutment threads from high functional loads, is the cause of this condition. [PERSON] et al. [31] evaluated bacterial leakage of _Enterococcus faecalis_ and _Aggregatibacter actinomycetemcomitants_ in two different Cone-Morse connections and found no leakage in both groups. The same author [4] observed leakage over a period of 14 days in internal and external connections and reported lower rates of infiltration in internal Cone-Morse connections. Although several articles conclude that implants with internal connections perform better results under loaded and unloaded experimental conditions compared to other typesof external and internal clearance-fit connections, a review by [PERSON] et al. [18] showed that all implant connections can undergo bacterial microleakage. However, when it comes to investigations using smaller molecules, such as bacterial endotoxins, the penetration of these occurred in all specimens of implants with internal conical connections. Despite several satisfactory studies, the results of this work show a certain bacterial infiltration in all the concentric connections analyzed. It is important to highlight that no statistically significant differences have been found among the three types of conical connections tested in this study. Another important point is that the percentage of infiltration at the 14 th day remained the same at the 90 th. This could confirm that the infiltration only happens in the first days as in the study by [PERSON] et al. in 2011 [3], in which the authors discovered microbial infiltration across the implant/abutment contact in periods spanning from 24 to 120 h.  
As hypothesized by literature in this type of experimentation, the static outgrowth model, there is the risk of contamination during the inoculation of bacterial inside to the platform. This is a limitation of this type of study, but the repetition of several experimentation and the statistical analysis are used also to reduce this risk of bias [18]. According to [PERSON] et al. [35], the stability and stress distribution of this kind of connection have reportedly been improved, and there has been reduced bacterial leakage as a result. According to reports, a more accurate adaptation of the various components and the application of appropriate torque forces are associated with superior stability of the implant abutment assembly. Variations in the internal conical connections can be caused by differences in taper angles, lengths of the taper section of the abutment, total abutment surface areas in contact with the internal aspect of the implant, and the geometry of the anti-rotational features. [18]. Precision in engineering part manufacturing and connection type design is particularly important [36]. [PERSON] et al. [36] found that the \(11^{\circ}\) Cone-Morse connection showed less bacterial infiltration compared to a butt-joint connection. Indeed, achieving stable hard and soft tissue integration requires that the implant-abutment interface be completely sealed against microorganisms [20; 37]. According to [PERSON] et al. [36], based on biological considerations, the Morse-Cone connection appears to be more effective because there is a connection between the funnel's two sides, as opposed to the butt-joint connection where the surfaces create a 90-degree angle.