Ion release from removable dental metal alloy prostheses in patients suffering from gastro-oesophageal reflux disease

Abstract

OBJECTIVES: This study investigated the release of metal ions from alloys used in removable dental prostheses and the potential effects on this ion release of gastro-oesophageal reflux disease (GORD). METHODS: 37 patients were recruited. Data was gathered through a questionnaire and clinical examination. Samples of metal alloy from the dentures and patient's saliva were collected. GORD was confirmed using the GerdQ questionnaire. Twelve (12) denture samples were characterized using Scanning Electron Microscopy & Energy Dispersive X-ray Spectroscopy, while 37 salivary samples were tested for metal ion concentrations using Inductively-Coupled Plasma - Emission Spectroscopy. RESULTS: Characterization of denture samples revealed the presence of two main alloys: nickel-chromium and cobalt-chromium. Nickel-chromium exhibited an etched surface pattern, while cobalt-chromium exhibited no apparent surface microstructural changes. The study revealed significant higher mean salivary levels of chromium (p=0.011) and cobalt (p=0.038) in patients wearing any metal alloy based denture, of chromium (p=0.047) and cobalt (p=0.013) in patients wearing a Co-Cr prosthesis and of chromium (p=0.034) and nickel (p=0.037) in patients wearing a Ni-Cr prosthesis. No significant differences were found in salivary metal ion levels of patients suffering from GORD. CONCLUSION: Nickel-chromium alloy is prone to acid etching in the oral cavity while cobalt-chromium alloy seems to be resistant. Cobalt, chromium and nickel are leached in saliva of patients making use of cast removable prostheses. The impact of gastric acid on metal ion release from dental metal alloys deserves further investigations.