Our results are consistent with the hypothesis that sour candies are more erosive than their original counterparts, particularly in an artificial saliva solvent. The objective of sour candies is to produce a more intense or longer lasting “tangy” flavor. The desired sourness can be achieved by adding more and/or different dietary acids. The candies studied herein contained fumaric, malic and citric acids; the concentration of each in the representative candies is unknown.
Lesion depths were inversely associated with initial pH and positively associated with titratable acidity in both artificial saliva and water solvents. Compared to water, the artificial saliva solvent was associated with higher pHs and lower titratable acidities for original candies, but not for sour candies. These data are supported by Wetton et al’s observation that human saliva can provide some protection against erosion associated with an in vitro citric acid challenge.27
Our artificial saliva contains sodium bicarbonate; the concentration appeared sufficient to buffer the original candies, but not the sour candies which likely contained more concentrated acids. Furthermore, artificial saliva contained calcium which can bind to dietary acids decreasing the titratable acidity and erosion potential.28
Calcium remaining in solution could also minimize the severity of erosion by leading to earlier saturation during dissolution.28
Our finding that most hard candies dissolved in artificial saliva were less erosive than those in water is supported by Jensdottir et al’s work documenting changes in salivary composition during acidic candy consumption.22
Human saliva produced during candy stimulation had higher concentrations of bicarbonate and protein leading to an increased in vivo buffering capacity. Combined with an increased salivary flow rate, the authors concluded that these changes in salivary composition offer some protection against erosion.22
Jensdottir et al have also demonstrated that calcium fortification of acidic candies decreases the erosion potential of the candies.23
Saliva produced by human subjects sucking on the fortified candies had similar drops in pH and phosphate concentrations, but significantly higher calcium concentrations than saliva produced with unfortified candies. The saliva produced by fortified candies was significantly less likely to dissolve hydroxyapatite crystals in vitro. Jensdottir et al’s use of human saliva stimulated by candy is unique.23
Previous studies in beverages with or without calcium fortification support our findings that calcium present in artificial saliva reduces the extent of erosion observed with original and sour candies. Calcium fortification of 100% juices and other beverages has been associated with decreased erosion, while both calcium and phosphate fortification of soft drinks are associated with a decreased erosion potential.14,19,29–31
Using in situ models in the United Kingdom, both Hughes et al29
and West et al30
developed minimally erosive blackcurrant juice drinks and carbonated beverages, respectively, by fortifying the beverages with calcium. We have previously reported that commercially available, calcium-fortified 100% juices from the United States were less erosive to both enamel and root surfaces using an in vitro model; however, the ability of calcium to prevent erosion was not absolute. Larsen and Nyvad31
reported that Danish orange juice containing calcium phosphate was less erosive in vitro than orange juice without calcium phosphate. Most investigators have reported that the pH of beverages is inversely associated with their erosion potential; however, associations between titratable acidity and erosion potential are more conflicting.14,15,17,31
The in vitro nature of the study design is our primary limitation and encompasses additional limitations including use of artificial saliva and the arbitrary time of exposure. The in vitro design prevents consideration of continuous saliva secretion in response to the tart stimulation as well as clearance of the dissolved candy through swallowing, and prevents the opportunity for remineralization between exposures. Artificial saliva does not contain proteins, which could provide additional buffering against potential erosion. The arbitrary time of exposure was based on pilot studies to ensure that differences in erosion could be detected, and not meant to mimic clinical conditions. Although the observed erosion is likely exaggerated by these limitations, the potential for both original and sour candies to erode enamel may be clinically relevant.
Dentists and hygienists should query patient’s dietary behaviors associated with acidic candies, and provide anticipatory preventive guidelines. Such candies are meant to be sucked upon for slow dissolution within the mouth, and would be expected to have a longer exposure time than is observed with other foods and beverages. Furthermore, holding candies within a cheek pocket or having diminished salivary flow could increase the candies’ concentration within the salivary fluid and, subsequently, increase risk of erosion. Sucking acidic candies has been demonstrated to stimulate salivary production and improve salivary buffering capacity in healthy, non-medicated volunteers.22
However, individuals with xerostomia often use such candies to treat their dry mouths, and the limited salivary flow could increase the acid concentration. Sanchez et al reported that children with erosion had lower salivary flow rates and buffering capacities than children without erosion.32