Characterization of biocorrosion by sulfate-reducing bacteria in extra-alveolar mini-implants installed in ex vivo human mandibles and exposed to the oral consortium of Desulfovibrio fairfieldensis: Microbiological, morphological, and mass loss analysis.

AIM: This study aimed to characterize the biocorrosive capacity of Desulfovibrio fairfieldensis oral in a consortium on the surface of Extra-alveolar mini-implants (EAMI) implanted in ex vivo human mandibles.

MATERIAL AND

METHODS

Nine extra-alveolar mini-implants (EAMI) were installed in ex vivo human mandibles. The EAMI were subjected to biocorrosion testing, immersed in artificial saliva, with an inoculum of D. fairfieldensis oral in consortium for 99 days. After this period, the cellular concentrations of the EAMI were determined through Most Probable Number (MPN) and quantitative Polymerase Chain Reaction (qPCR), in addition to analysis by scanning electron microscopy and epifluorescence.

RESULTS

The qPCR showed a reduction in the bacterial load from 1.70×107 to 1.90×104 cells/mL, while MPN indicated that the number of culturable cells was greater than 2.4×104 cells/mL. Biofilms associated with EAMI exposed to Sulfate-reducing bacteria (SRB) exhibited a low cell density (4-7.5×101 cells/cm2). Despite the formation of biofilms on exposed surfaces, no corrosion pits were observed. Corrosion rates were not significantly lower in EAMI exposed to SRB (0.0003418±0.0025805mm/year) compared to controls (0.011621±0.0176811mm/year; P=0.200).

CONCLUSIONS

The D. fairfieldensis oral consortium is capable of adhering to the metallic titanium surface of the EAMI, forming biofilms in areas exposed to the external environment and at the interface between the anchorage, bone, and threads of the EAMI. However, the titanium composition of the EAMI results in a low and non-significant corrosion rate, with no corrosion pits observed in these areas.