Morphological and chemical characterization of tooth enamel exposed to alkaline agents.
OBJECTIVE
In this study, morphological and chemical changes in teeth enamel exposed to alkaline agents, with or without surfactants, have been investigated. In addition, chemical effects of the organic surface layer, i.e. plaque and pellicle, were also investigated.


METHODS
The present study was conducted using several techniques: Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM).


RESULTS
From XPS-measurements, it was found that exposure to alkaline solutions resulted in a massive removal of carbon from the tooth surface, and that the addition of surfactants increased the rate under present conditions. Based on the results from the FTIR-analysis, no substitution reactions between phosphate, carbonate and hydroxide ions in the enamel apatite could be detected. From a minor SEM-analysis, degradation and loss of substance of the enamel surface was found for the exposed samples. From XRD-analysis, no changes in crystallinity of the enamel apatite could be found between the samples.


CONCLUSIONS
The findings in this study show that exposure to alkaline solutions results in a degradation of enamel surfaces very dissimilar from acidic erosion. No significant erosion or chemical substitution of the apatite crystals themselves could be discerned. However, significant loss of organic carbon at the enamel surface was found in all exposed samples. The degradation of the protective organic layer at the enamel surface may profoundly increase the risk for caries and dental erosion from acidic foods and beverages.
Taube
F
F
Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital, SE-405 30 Gothenburg, Sweden. abian.taube@amm.gu.se
Ylmén
R
R
Shchukarev
A
A
Nietzsche
S
S
Norén
J G
JG
D000468:Alkalies / Q000494:pharmacology*; D001031:Apatites / Q000032:analysis; D002118:Calcium / Q000032:analysis; D002244:Carbon / Q000032:analysis; D002254:Carbonates / Q000032:analysis; D003461:Crystallography; D003743:Dental Enamel / Q000737:chemistry / Q000187:drug effects* / Q000648:ultrastructure; D044622:Dental Pellicle / Q000737:chemistry / Q000187:drug effects / Q000648:ultrastructure; D003773:Dental Plaque / Q000737:chemistry / Q000473:pathology / Q000503:physiopathology; D003902:Detergents / Q000494:pharmacology; D006801:Humans; D006878:Hydroxides / Q000032:analysis / Q000494:pharmacology*; D008855:Microscopy, Electron, Scanning; D010710:Phosphates / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D056951:Photoelectron Spectroscopy; D017680:Potassium Compounds / Q000494:pharmacology*; D017550:Spectroscopy, Fourier Transform Infrared; D013464:Sulfuric Acids / Q000494:pharmacology; D013501:Surface-Active Agents / Q000494:pharmacology; D017001:Tooth Demineralization / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D014961:X-Ray Diffraction
D000468:Alkalies; D001031:Apatites; D002254:Carbonates; D003902:Detergents; D006878:Hydroxides; D010710:Phosphates; D017680:Potassium Compounds; D013464:Sulfuric Acids; D013501:Surface-Active Agents; D010758:Phosphorus; D002244:Carbon; C031356:hydroxide ion; C033158:sulfuric acid; D002118:Calcium; C029943:potassium hydroxide