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, 6mg KOH; (B) 0.125%F, RDA: 125, 24mg KOH; (C) 0.125%F, RDA: 129, 12mg KOH; (D) 0%F, RDA: 81, 1.55mg KOH; (E) 1.25%F, RDA: 21, 8.5mg KOH; (F) 0.125%F, RDA: 7, 3.11mg KOH. Ten specimens were cycled through three alternating demineralisations (1% citric acid, 5min) and remineralisations (artificial saliva, 1min) including brushing abrasion in an automatic brushing machine (2 x 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. [microm]). 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<or=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.