Enamel Erosion by Some Soft Drinks and Orange Juices Relative to Their pH, Buffering Effect and Contents of Calcium Phosphate

Abstract

The capability of a soft drink or a juice to erode dental enamel depends not only on the pH of the drink, but also on its buffering effect. As the latter is the ability of the drink to resist a change of pH it may add to the effects of the actual pH. The aim of the present study was to compare the pH and the buffering effect of various soft drinks with their erosive effects and the solubility of apatite. In 18 soft drinks, mineral waters and juices available on the Danish market, pH and the concentrations of calcium, phosphate and fluoride were determined. The buffering effect was determined by titration with NaOH. Human teeth (n = 54) covered with nail varnish except for 3×4–mm windows were exposed to 1.5 liters of the drink for either 7 days or 24 h under constant agitation. The depth of the erosions was assessed in longitudinal sections. The depth was found to vary greatly from 3 mm eroded by the most acidic drinks and fresh orange juice to only slightly affected surfaces by most of the mineral waters. The dissolution of enamel increased logarithmically inversely with the pH of the drink and parallel with the solubility of enamel apatite. Orange juice, pH 4.0, supplemented with 40 mmol/l calcium and 30 mmol/l phosphate did not erode the enamel as the calcium and phosphate saturated the drink with respect to apatite. Generally, the lower the pH the more NaOH was necessary to bring the pH to neutrality. In particular the buffering effect of the juice was high. For all drinks, no effect of their low fluoride concentrations was observed.

Acidic beverages increase the risk of in vitro tooth erosion

“…Beverage compositions vary widely; the milieu of nutrients and nonnutrients likely influences the capacity for erosion [16,17]. Calcium and fluoride have been shown to limit the extent of erosion by saturating the solution and/or altering the solubility of enamel [1,9,12,14,18].…”

“…The in vitro erosion potential of representative commercial beverages was evaluated using extracted human permanent teeth [9]. The in vitro model was selected because the intact enamel or dentin surface is exposed to the beverage and the model allows for observation of demineralization within a reasonable time period.…”

“…European investigators have studied acidic foods and beverages as risk factors for enamel erosion with most investigations focusing on acidic beverages [5][6][7][8][9][10][11]. Larsen et al [9] of Denmark investigated the in vitro erosive potential of soft drinks, mineral waters and orange juices and compared erosion depths to pH and buffering capacity of the beverages.…”

“…Larsen et al [9] of Denmark investigated the in vitro erosive potential of soft drinks, mineral waters and orange juices and compared erosion depths to pH and buffering capacity of the beverages. They reported that erosion was minimal in beverages containing a pH above 4.2, but became more evident with pHs decreasing below 4.0.…”

A laboratory investigation of consumer addition of UHT milk to lessen the erosive potential of fizzy drinks

“…a strong preventive effect upon dental erosion. 15 In addition, the naturally high levels of calcium in fi zzy mineral waters have been shown in the laboratory to inhibit hyroxyapatite dissolution. 16 Furthermore, an in vitro study has demonstrated that the addition of calcium to acidic candies results in a reduction of their capacity to bring about dental erosion.…”