Spectroscopic and microscopic examination of teeth exposed to green tea at different temperatures

PLoS One. 2020 Dec 30;15(12):e0244542. doi: 10.1371/journal.pone.0244542. eCollection 2020.

Abstract

Tea is a popular beverage consumed at different temperatures. The effect of tea on teeth at different temperatures has not been studied previously. The present study used an in vitro green tea immersed tooth model at different tea temperatures (hot and cold) compared to an in vivo tea administration model allowing rats to drink tea over the course of a week. The elements present in tea leaves were identified by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and compared to the elements in teeth (enamel surface) using Laser-Induced Breakdown Spectroscopy (LIBS). Here, LIBS demonstrated in vivo and in vitro green tea treatments resulted in a significant increase in the mineral elements found in enamel. For the in vitro assessment, elements in enamel varied based on cold-tea and hot-tea treatment; however, hot water reduced the elements in enamel. Atomic force microscopy found the in vivo tea group had a higher roughness average (RA) compared with the in vivo water group. Cold tea and hot tea in vitro groups demonstrated lower RA than in vitro water controls. Scanning electron microscopy found hot water induced cracks more than 1.3μm in enamel while cold tea and hot tea promoted the adhering of extrinsic matter to teeth. Overall, teeth treated to high temperature lost the mineral phase leading to demineralization. Our results indicate that green tea protects enamel, but its protective action in dental structures is enhanced at cold temperature.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Camellia sinensis / chemistry*
  • Cold Temperature
  • Hot Temperature
  • Male
  • Mass Spectrometry
  • Microscopy, Atomic Force
  • Microscopy, Electron, Scanning
  • Models, Animal
  • Plant Extracts / administration & dosage*
  • Plant Extracts / chemistry
  • Plant Extracts / pharmacology
  • Plant Leaves / chemistry
  • Rats
  • Surface Properties
  • Tea / chemistry*
  • Tooth / drug effects
  • Tooth / ultrastructure*

Substances

  • Plant Extracts
  • Tea

Grants and funding

This work was supported in part by the Hong Kong Research Grants Council (ECS CityU21201217 to CL) and the City University of Hong Kong (9610338, 9610378, and 7005507 to CL). It was also supported by the University of Hong Kong (9610348 to SHC) and CONACYT, CVU 622691 (support number: 739501 to SHCM). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.