Researchers at the Korea Advanced Institute of Science and Technology (KAIST) have developed a new method for using atomic force microscopy (AFM) to quantitatively evaluate how acidic and sugary drinks affect human tooth enamel at the nanoscale level. According to the researchers, this novel approach is useful for measuring mechanical and morphological changes that occur over time during enamel erosion induced by beverages.
Enamel is the hardest substance in the human body. Its resilient surface is 96% mineral, which is the highest percentage of any body tissue, making it durable and resistant to damage. It acts as a barrier to protect the soft inner layers of the tooth, but it can become susceptible to degradation by acids and sugars.
Erosion occurs when enamel is overexposed to excessive consumption of acidic and sugary food and drinks. If left untreated, enamel loss can lead to conditions including stains, fractures, sensitivity, and translucence. Once enamel is damaged, it can’t be brought back. Therefore, the researchers said, thorough studies on how enamel erosion starts and develops, especially at the initial stages, are of high scientific and clinical relevance for dental health maintenance.
AFM is a very high-resolution type of scanning probe microscopy (SPM), with demonstrated resolution on the order of fractions of a nanometer that is equal to one billionth of a meter. It generates images by scanning a small cantilever over the surface of a sample, precisely measuring the structure and mechanical properties of the sample such as surface roughness and elastic modulus.
Five healthy human molars were obtained from volunteers between the ages of 20 and 35 who visited the KAIST Clinic. After extraction, the teeth were preserved in distilled water before the experiment. The researchers then immersed the teeth in Coca-Cola, Sprite, and Minute Maid orange juice. The drinks were purchased and opened right before immersion, and the team later used AFM to measure the surface topography and elastic modulus map of the molars.
The surface roughness of the tooth enamel increased significantly as the immersion time increased, while the elastic modulus of the enamel surface decreased drastically. The enamel surface roughened five times more when it was immersed in beverages for 10 minutes, and the elastic modulus of tooth enamel was five times lower after five minutes in the beverages.
Also, the researchers found preferential etching in scratched tooth enamel. Brushing your teeth too hard and toothpastes with polishing particles that are advertised to remove dental biofilms can cause scratches on the enamel surface, which can be preferential sites for etching, the study revealed.
“Our study shows that AFM is a suitable technique to characterize variations in the morphology and mechanical properties of dental erosion quantitatively at the nanoscale level,” said professor Seungbum Hong of the KAIST Department of Materials Science and Engineering.
The study, “Nanoscale Effects of Beverages on Enamel Surface of Human Teeth: An Atomic Force Microscopy Study,” was published by the Journal of the Mechanical Behavior of Biomedical Materials.
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