Oral microbiota accelerates corrosion of 316L stainless steel for orthodontic applications

Abstract

• Multi-species biofilms well attach to the surface of 316L SS. • Oral microbiota accelerates the corrosion of 316L SS. • Oral microbiota causes severe pitting corrosion of 316L SS. • Electroactive microorganisms are detected in the multi-species biofilms. In this work, microbiologically influenced corrosion (MIC) of 316L stainless steel (SS) caused by oral microbiota was investigated with HOMINGS 16S rRNA gene sequencing technology, and electrochemical and surface analysis techniques. The results showed that oral microbiota from different subjects developed multi-species biofilms with significant differences in structure and composition of bacteria strains on the 316L SS coupons. In the presence of oral microbiota, more severe pitting corrosion and faster dissolution of metallic ions including Ni and Cr were observed. The biofilm considerably decreased the pitting potential of 316L SS from 1268.0 ± 29.1 mV vs. SCE (abiotic control) to less than 500 mV vs. SCE. The corrosion current density in the presence of oral microbiota from subject 1 (115.3 ± 83.3 nA cm −2 ) and subject 2 (184.4 ± 162.0 nA cm −2 ) was at least 4 times more than that in the abiotic medium (28.0 ± 2.3 nA cm −2 ). The electroactive microorganisms with the potential to facilitate corrosion via extracellular electron transfer found in oral microbiota may be mainly responsible for the accelerated corrosion.