Spectroscopic examination of enamel staining by coffee indicates dentin erosion by sequestration of elements

摘要

The mechanism of coffee eliciting erosion on teeth is unclear as few studies have investigated the direct effect of coffeeon enamel and dentin structures. The present study identified how coffee, the most popular beverage worldwide, inducesstaining and erosion on teeth. We show the grade of erosion of molars and incisors in Sprague Dawley rats from twodifferent age groups, young (four weeks) and old (six months). We quantified the concentration of metals contained incoffee by mass spectrometry (ICP-MS). To determine elemental content in enamel (i.e. superficial) and dentin (i.e.substructure), we used Laser-induced Breakdown Spectroscopy (LIBS) and X-ray fluorescence (XRF) spectroscopy,respectively. For LIBS, a significant decrease of Ca, P, and Na was observed in the young coffee group relative to agematchedcontrols, whereas a significant increase in Mn, Fe, and K was observed. In the old coffee group, a significantincrease of Mg, Fe, and K was observed along with a decrease of Mg, Ca, P, Na, Sr and Zn. For XRF, a significantdecrease of the Ca/P ratio in the coffee group was observed. The SEM analysis showed pores and open spaces betweenyoung and old coffee groups, respectively. Thinning of enamel layers, loss of continuity in the enamel-dentin-junction,and wide spaces in dentin tubules with coffee use was found histologically. Coffee induces decalcification of teeth thatcorresponds to erosion, exposing the dentin structure by reducing enamel. Coffee immersion demonstrated an intrinsicstaining in dentin by metal deposition.