Abstract

Background: The effect of tea on teeth under temperature conditions has not been studied previously.

Model: The present study used an in vitro one-week immersed tooth model with different tea temperatures, hot and cold. An in vivo tea administration model, allowing rats to drink tea over the course of a week, was also performed.

Methods: Elemental content of tea leaves was identified by ICP-MS, Laser-Induced Breakdown Spectroscopy (LIBS) for elemental spectrum analysis, Atomic Force Microscopy (AFM) for roughness analysis, scanning electron microscopy for ultrastructural assessment and histology used for structural assessments.

Results: The LIBS analysis demonstrated a significant increase in the mineral elements (Zn, Mg, Ca, Sr and Fe) from tea in vivo. For in vitro, increases of Fe and K were significantly higher in the hot-tea group than in the cold-tea group, with a decrease of the elements in hydroxyapatite forming teeth, albeit not statistically significance, though. The LIBS showed that in vitro cold-tea group drastically increased Zn, C, Ca, Mn, Mg, P, Sr, Fe and K compared with cold-water. While in vitro hot-tea group was significantly increased in Mg, Ca, Sr, Fe and K compared with hot-water. The AFM did not show a significance difference among groups in vivo or in vitro, but in vivo tea presented a higher roughness compared with cold-tea, hot-tea and hot-water, indicating a polishing effect due to temperature and tea. Using scanning electron microscopy, hot-water induced cracks more than 1µm while cold-tea and hot-tea revealed extrinsic matter adhered to teeth. Histological analysis showed considerable increase in the percentage of mineralization from cold tea on the enamel surface.

Conclusion: Under cold conditions, tea prompted an interaction of the inorganic components in teeth: Ca, Mg, P, Fe and K. An accumulation in the organic matrix was promoted by tea. However, high temperature facilitated deposition of metals associated with teeth staining. Moreover, under hot temperature teeth lost the mineral phase leading to demineralization. Even though green tea protects enamel, its potential is susceptible to prompting demineralization over dental structures under high temperatures.

© 2019 SPIE/OSA