BMC Oral Health. 2026 May 25. doi: 10.1186/s12903-026-08639-2. Online ahead of print.
ABSTRACT
BACKGROUND: Additive manufacturing of cobalt-chromium (Co-Cr) and titanium (Ti-6Al-4 V) alloys is increasingly used in prosthetic dentistry. Acidic oral environments associated with gastroesophageal reflux disease (GERD) may negatively influence the surface integrity and corrosion resistance of dental materials. This in vitro study assessed the effects of simulated gastric acid on the corrosion resistance, surface morphology, and topographical changes of selective laser melting (SLM) Co-Cr and Ti-6Al-4 V alloys.
METHODS: Thirty-two additively manufactured specimens (n = 16 per alloy) were randomly distributed into acidic (pH 1.2) and neutral control (pH 6.7 distilled water) subgroups (n = 8). A cyclic static immersion protocol was used to simulate GERD-related acid exposure. Specimens in the acidic group were immersed for 2 min in acidic solution, rinsed without scrubbing to preserve the delicate surface topography, and stored in distilled water at 37 °C, repeated six times daily over nine days with a 24-hour interval maintained between each daily cycle. Control specimens were stored continuously in distilled water at 37 °C. Surface morphology, elemental composition, and topography were evaluated using scanning electron microscopy (SEM) and Abbott-Firestone curve analysis.
RESULTS: In the Co-Cr alloy, immersion in an acidic solution resulted in a decrease in the percentage of all elements, except O, which increased to 6.37 ± 1.77%, with the change being statistically significant (P ≤ 0.05). In contrast, Ti-6Al-4 V also showed a decrease in all elements after immersion, with O rising to 2.26 ± 1.22%, although no changes were statistically significant (P ≥ 0.05). SEM images indicated more oxide deposits on Co-Cr in an acidic solution, which also showed a notable increase in surface roughness, whereas Ti-6Al-4 V exhibited greater stability. The Abbott-Firestone analysis further confirmed that Co-Cr underwent more significant changes in peak formation and exploitation zones than Ti-6Al-4 V did in acidic environments.
CONCLUSIONS: Under simulated gastric acid exposure, Ti-6Al-4 V alloys exhibited superior corrosion resistance and surface stability compared with Co-Cr alloys. These findings support the clinical preference for Ti-6Al-4 V in dental restorations for patients experiencing frequent acidic challenges, such as those with severe GERD.
PMID:42178550 | DOI:10.1186/s12903-026-08639-2
