Acidic beverages increase the risk of in vitro tooth erosion

Abstract

Acidic beverages are thought to increase the potential for dental erosion. We report pH and titratable acidities (ie, quantity of base required to bring a solution to neutral pH) of beverages popular in the United States and lesion depths in enamel and root surfaces after beverage exposure, and we describe associations among pH, titratable acidity, and both enamel and root erosive lesion depths. The pH of 100% juices, regular sodas, diet sodas, and sports drinks upon opening and the titratable acidity both upon opening and after 60 minutes of stirring were measured. Enamel and root surfaces of healthy permanent molars and premolars were exposed to individual beverages (4 enamel and 4 root surfaces per beverage) for 25 hours, and erosion was measured. Statistical analyses included 2-sample t tests, analyses of variance with post hoc Tukey studentized range test; and Spearman rank correlation coefficients. All beverages were acidic; the titratable acidity of energy drinks was greater than that of regular and diet sodas that were greater than that of 100% juices and sports drinks (P < .05). Enamel lesion depths after beverage exposures were greatest for Gatorade, followed by those for Red Bull and Coke that were greater than those for Diet Coke and 100% apple juice (P < .05). Root lesion depths were greatest for Gatorade, followed by Red Bull, Coke, 100% apple juice, and Diet Coke (P < .05). Lesion depths were not associated with pH or titratable acidity. Beverages popular in the United States can produce dental erosion.

Introduction

Dental erosion is defined as the chemical removal of mineral from the tooth structure [1], [2]. Erosion is classified as extrinsic (ie, diet) or intrinsic (ie, gastroesophageal) in origin [1], [2], [3]. Erosion is typically progressive and results in the wearing away of the exposed tooth surface (ie, enamel or root surface). Dental caries, on the other hand, is the site-specific acid destruction of tooth surface associated with bacterial fermentation of sugars in the oral cavity.

Dental erosion is considered a significant oral health concern in European and Middle Eastern countries. Dugmore and Rock [4] reported a tooth erosion prevalence of 59.7% in a random sample of 12-year-old British children from Leicestershire and Rutland counties participating in a national dental health survey. Erosion prevalence rates of 34% and 26% have been reported for 5- to 6-year-old and 12- to 14-year-old boys, respectively, in Saudi Arabia [5]. Similar results were reported for 5-year-old Irish school children; 47% exhibited some erosion [6]. In the United States, dental erosion has not been identified as a primary oral health concern in children at this time, and similar prevalence rates are not available.

Some, but not all, observational studies support an association between acidic beverage (ie, fruit juices, sodas, sports drinks) consumption and dental erosion. Al-Majed et al [5] reported that the number of permanent maxillary incisors with erosion in Saudi Arabian children was associated with frequency of night beverage intakes and length of beverage time in the mouth. The frequency of fruit and carbonated drink intakes was associated with severe erosion in 5-year-old Irish children [6]. Neither Milosevic et al [7] in British adolescent athletes nor Mathew et al [8] in United States collegiate athletes identified an association between sports drink consumption and erosion.

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 and Nyvad [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. Hunter et al [10] of the United Kingdom examined the in vitro susceptibility of permanent and deciduous teeth to erosion by soaking extracted teeth in a low-pH fruit drink diluted with mineral water. Increasing length of exposure to the fruit drink was associated with more severe erosion; however, the severity of erosion was not proportional to the length of exposure. Rees et al [11] reported that sports drinks based on acidic fruits popular in the United Kingdom have low pHs and are erosive when enamel is immersed in the sports drink.

Although dental erosion has been identified as a significant oral health concern in European countries, it has received much less attention in the United States. Secular trends in beverage habits in the United States including increased consumption of sodas, 100% juices, and juice drinks, as well as the introduction of sports drinks and energy drinks, could increase the risk of erosion. Furthermore, the nature of consumption (ie, sipping for extended periods or concurrent with mouth breathing during athletic training) could increase the opportunity for erosion to occur. Erosion is a gradual process; the secular changes have occurred fairly quickly may have limited our ability to observe erosive effects of acidic beverages in the population.

Although we have previously described the protection against erosion associated with calcium fortification of 100% fruit juices [12], the erosion potential of beverages popular in the United States has not been thoroughly investigated. We hypothesize that acidic beverages popular in the United States erode both enamel and root surfaces. Knowledge of the erosion potential of popular beverages is important for clinical guidelines regarding beverage consumption practices and development of potentially “safer” beverages. The objectives of this manuscript are to report pH and titratable acidities (ie, quantity of base required to bring a solution to neutral pH) of beverages popular in the United States, to report lesion depths in enamel and root surfaces after beverage exposure, and to describe associations among pH, titratable acidity, and both enamel and root erosive lesion depths.