Influence of buffering effects of dentifrices and fluoride gels on abrasion on eroded dentine

Objective: Evaluation of abrasion resistance of eroded and non-eroded dentine brushed with experimental dentifrices and gels of varying buffering capacities. Design: One hundred and twenty human dentine specimens were distributed among six groups (A–F) according to the different buffering capacities of experimental toothpastes and gels. The dentifrices (pH: 4.5) and gels (pH: 4.5) differed in fluoride content, RDA-value and buffer capacity (given as mg KOH needed for neutralisation): (A) 0.125%F, RDA: 77, 6 mg KOH; (B) 0.125%F, RDA: 125, 24 mg KOH; (C) 0.125%F, RDA: 129, 12 mg KOH; (D) 0%F, RDA: 81, 1.55 mg KOH; (E) 1.25%F, RDA: 21, 8.5 mg KOH; (F) 0.125%F, RDA: 7, 3.11 mg KOH. Ten specimens were cycled through three alternating demineralisations (1% citric acid, 5 min) and remineralisations (artificial saliva, 1 min) including brushing abrasion in an automatic brushing machine (2×2000 strokes). Ten samples of each group were not eroded, but only brushed. Results: After three cycles, loss of dentine was determined by profilometry (mean±S.D. [μm]). Eroded samples: (A) 37.12±4.95; (B) 48.67±4.77; (C) 39.88±3.76; (D) 32.92±2.67; (E) 3.65±1.35; (F) 6.47±1.31. Uneroded samples: (A) 30.78±6.47; (B) 37.84±7.75; (C) 30.07±3.05; (D) 26.93±2.30; (E) 1.76±0.94; (F) 0.51±0.18. Analysis of variance revealed significantly higher abrasion values for the eroded compared to the non-eroded samples (P≤0.05). Dentifrices with same pH-value, fluoride content and similar RDA-values but a higher buffering capacity exhibited significantly more abrasion than toothpastes with lower buffering capacity. Highly-concentrated fluoride gel with higher buffering capacity lead to less abrasion values compared to the gel with low fluoride concentration and low buffering capacity. Conclusion: Toothbrushing abrasion behaviour of eroded dentine may be influenced by the fluoride content, RDA-value and buffering capacity of the applied dentifrice or gel.