Influence of apple juice on human enamel surfaces of the first and second dentition - an in vitro study

Dental erosion caused by acidic beverages is common and occurs with increasing tendency. The aim of this in vitro study was to analyse the erosive potential of apple juice on human enamel samples from the first and second dentition. Apple-juice-containing beverages (n = 23) were selected, and pH and buffering capacity were determined. Enamel samples were prepared from impacted, surgically removed wisdom teeth (20 mm superset2) and from deciduous teeth (16 mm superset2). Prepared enamel slices were incubated with a selected apple juice (pH = 3.5) for up to 24 h; the amounts of released calcium were determined colorimetrically, and mean surface roughness (Ra) of the enamel was measured using an optical profilometric device (perthometer, Mahr, Göttingen, Germany). Controls were incubated with a 0.9 % sodium chloride solution under the same conditions (37 degrees C, humidified atmosphere of 5% CO subset2 and 95 % air). The surfaces of the enamel samples were visually examined by CLSM (Leica TCS SP2). The pH-values of the apple juices ranged from 3.3 to 4.2. Incubating the enamel slices (from both dentitions) with a selected apple juice caused a time dependent release of calcium. After 24 h, the primary dentition showed Ca-release values of 0.61 +/- 0.035 mg/ 20 mm superset2 and the second dentition of 0.41 +/- 0.085 mg/ 20 mm superset2; the surface roughness for the primary teeth was 6.8 +/- 1.09 microm and for the second dentition 6.2 +/- 0.41 microm. CLSM show structural changes on all surfaces when compared to the controls. In this in vitro study, the erosive potential of apple juice on teeth of the first and second dentition could be demonstrated. However, it must be considered that numerous modifying factors influence the human enamel surface in vivo; therefore, a direct translation from in-vitro conditions can only be done with caution.