Surface Microstructural Changes and Release of Ions from Dental Metal Alloy Removable Prostheses in Patients Suffering from Acid Reflux

Abstract

Purpose: To investigate the surface microstructural changes and the release of ions from metal alloys used in removable dental prostheses and the potential effects of acidic reflux found in patients suffering from gastroesophageal reflux disease (GERD).

Materials and methods: Thirty-seven (37) patients were recruited. Data were gathered through a questionnaire and clinical examination. Samples of metal alloy from the dentures and patient's saliva were collected. GERD was confirmed using the GerdQ questionnaire. Denture samples were characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), while salivary samples were tested for trace metal ions using inductively coupled plasma (ICP).

Results: Characterization of denture samples revealed the presence of nickel, cobalt, and chromium. Nickel-chromium exhibited an etched surface appearance, while cobalt-chromium exhibited no noticeable surface microstructural changes. Higher mean salivary levels of chromium and cobalt in patients wearing any metal alloy-based denture and of chromium and nickel in patients wearing Ni-Cr prostheses were found to be significant. No differences were found in salivary metal ion levels of patients suffering from GERD.

Conclusions: Nickel-chromium alloy is prone to acid etching in the oral cavity, while cobalt-chromium alloy appears to be more resistant. Cobalt, chromium, and nickel are leached in saliva of patients using cast removable prostheses. The impact of gastric acid on metal ion release from dental metal alloys deserves further investigations.

Clinical significance: This preliminary study suggests that metal-based removable prostheses leach trace metal ions in saliva. Nickel-chromium-based dentures exhibit an etched appearance unrelated to GERD.

Keywords: Metal alloy prosthesis; chromium; cobalt; gastroesophageal reflux disorder; leaching; molybdenum; nickel; surface microstructure.