Objective: To evaluate effect of PRG barrier coat versus NaF varnish and their combined application on microhardness and surface roughness of eroded-abraded enamel during chemo-mechanical cycling.
Material and Methods: 28 human premolars were randomly divided into 4 groups according to preventive treatment (7/group): Group 1, artificial saliva; Group 2, PRG barrier coat; Group 3, NaF varnish; Group 4, NaF varnish + PRG barrier coat. Before treatment, specimens underwent 3 consecutive days of erosion/abrasion challenge (4-erosion “energy drink", 2-abrasion cycles/day), and stored in artificial saliva in-between cycles, overnight. Treatment was applied following grouping, then another 3-day cycle was conducted. Microhardness and surface roughness were assessed at baseline, after first cycling before treatment, after treatment and second cycling. Comparisons between four groups were performed using Kruskal-Wallis test, within each group using Friedman test.
Results: The highest median %change of enamel increase in microhardness and decrease in surface roughness were recorded for Groups 3 and 4, respectively. Group 2 showed the lowest median %change. There was no statistically significant difference between all groups regarding microhardness and surface roughness (p = 0.119 and 0.248, respectively).
Conclusions: Irrespective of preventive treatment, microhardness and surface roughness of eroded-abraded enamel did improve after exposure to chemo-mechanical challenge.