Root caries is a condition that has become more prevalent with increasing life expectancy and therefore associated with the elderly. Thus, the use of high- fluoride (F) toothpastes (5,000 µg F/g) and toothpaste with standard concentration (1,450 µg F/g) associated with arginine suggest improved effect compared to standard toothpastes (1,000-1,450 µg F/g) on progression of root caries. This study will evaluate the effect of these toothpastes in the control of root caries. Two independent studies, one in vitro and other in situ, will be conducted in which bovine dentin specimens will be selected by surface hardness. In the in vitro study, 36 bovine dentin slabs will be used to assess the inhibition of demineralization. Specimens will be randomized among 3 treatment groups (n=12) and submitted to pH-cycling model, which will last 8 days, remaining daily for 6 h in demineralizing solution and 18 h in remineralizing solution, at 37°C. Slabs will be treated 2x/day, before and after immersion in demineralizing solution. Treatments will be performed with standard toothpaste (1,100 µg F/g-Control group), high-F concentration (5,000 µg F/g) and with conventional concentration (1,450 µg F/g) associated with 1,5 % arginine. For analysis of the variables, percentage of surface hardness loss (%SHL), carious lesion area (S) and microradiography will be determined in each slab. In the second study, in situ, this will be conducted in triple blind method, during 2 weeks, involving 15 volunteers divided into 3 groups (n=5), who will use a palatine intraoral appliance containing 4 bovine dentin slabs (2 on each side) Of these slabs, 2 will be sound and 2 will be previously induced to demineralization, prior to its insertion on the appliance. Sound slabs will be exposed 8x / day to 20% sucrose, simulating high cariogenic challenge situation. Volunteers will brush the slabs on the appliance 3 x/day with the same toothpaste designated. %SHL in slabs initially sound and surface hardness recovery (%SHR) in artificially carious-like slabs will be analyzed and, zone carious lesion and microradiography will also be conducted to assess the depth of carious lesion.
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