Enamel surface loss after erosive and abrasive cycling with different periods of immersion in human saliva

Abstract

ObjectiveThis in vitro study aimed to evaluate different periods of exposure to clarified human saliva for the ability to protect enamel against erosive tooth wear. MethodsFor this purpose, sixty specimens (4 × 4 × 1.5 mm) were prepared from third human molars. For all groups, the period before abrasion was performed by remineralisation with human saliva (except in G1). The specimens were randomly divided into six groups (n = 10) according to the different remineralisation times of exposure to clarified human saliva: no exposure to saliva (G1) and 30 min (G2), 60 min (G3), 90 min (G4), 120 min (G5), and 240 min (G6) of exposure to human saliva. A 5-day cycling was performed with 5 min of erosion (1% citric acid; pH 2.3), 4x/day. After the first and last erosive episodes, the abrasion challenge was performed with slurry of fluoride toothpaste (1450 ppm F−, as sodium monofluorophosphate) plus human saliva (1:3), with an electric toothbrush (15 s, with a total of 120 s of slurry immersion). Surface loss (SL) was determined using an optical profilometer (n = 10) and for qualitative analysis, environmental scanning electron microscopy (ESEM) was performed (n = 3). The SL data were statistically analysed by one-way analysis of variance (α = 0.05). ResultsNo significant differences were detected among the groups for SL (p > 0.05), and ESEM showed similar aspects of eroded enamel. ConclusionsThe period of in vitro exposure to clarified human saliva was not able to protect against enamel erosion.