Abstract This study evaluated the effect of fluoride varnishes containing micrometric or nanosized sodium trimetaphosphate (TMP) on dentin erosive wear in vitro. Bovine root dentin blocks were selected by surface hardness and randomly divided into five experimental groups/varnishes (n = 20/group): placebo, 5% sodium fluoride (NaF); 5% NaF+5% micrometric TMP; 5% NaF+2.5% nanosized TMP; and 5% NaF+5% nanosized TMP. Half of the surface of all blocks received a single application of the assigned varnish, with subsequent immersion in artificial saliva for 6 h. Varnishes were then removed and the blocks were immersed in citric acid (90 s, 4×/day, 5 days). After each erosive cycle, ten blocks of each group were immersed in a placebo dentifrice for 15 s (ERO), while the other ten blocks were subjected to abrasion by brushing (ERO+ABR). Dentin erosive wear was assessed by profilometry. Data were submitted to 2-way ANOVA and to the Holm-Sidak test (p<0.05). Dentin erosive wear was significantly higher for ERO+ABR than for ERO for all varnishes. TMP-containing varnishes promoted superior effects against dentin erosive wear compared with 5% NaF alone; and 5% nanosized TMP led to the lowest wear among all varnishes. In conclusion, the addition of TMP to conventional fluoride varnish (i.e., varnish containing only NaF) enhanced its protective effects against bovine root dentin erosion and erosion+abrasion. Additionally, the use of 5% nanosized TMP led to superior effects in comparison to 5% micrometric TMP, both for erosion and erosion+abrasion in vitro. (TMP vitro groupsvarnishes groups n 20/group 20group 20 20/group) (NaF) NaF5 NaF+5 NaF25 2 NaF+2.5 h 90 (9 4day day 4 4×/day days. days . days) cycle 1 ERO, , (ERO) ERO+ABR. EROABR ABR (ERO+ABR) profilometry 2way way HolmSidak Holm Sidak p<0.05. p005 p p<0.05 0 05 (p<0.05) TMPcontaining alone conclusion i.e., ie i e (i.e. erosionabrasion Additionally (NaF NaF+ NaF2 NaF+2. 9 ( (ERO (ERO+ABR p00 p<0.0 (p<0.05 i.e. (i.e NaF+2 p0 p<0. (p<0.0 i.e p<0 (p<0. p< (p<0 (p< (p

Abstract Objective To evaluate the effects of fluoride (F) gels supplemented with micrometric or nano-sized sodium trimetaphosphate (TMPmicro and TMPnano, respectively) on the in vitro remineralization of caries-like lesions. Methodology Bovine enamel subsurface lesions (n=168) were selected according to their surface hardness (SH) and randomly divided into seven groups (n=24/group): Placebo (without F/TMP), 4,500 ppm F (4500F), 4500F + 2.5% TMPnano (2.5% Nano), 4500F + 5% TMPnano (5% Nano), 4500F + 5% TMPmicro (5% Micro), 9,000 ppm F (9000F), and 12,300 ppm F (Acid gel). The gels were applied in a thin layer for one minute. Half of the blocks were subjected to pH cycling for six days, whereas the remaining specimens were used for loosely- (calcium fluoride; CaF2) and firmly-bound (fluorapatite; FA) fluoride analysis. The percentage of surface hardness recovery (%SHR), area of subsurface lesion (ΔKHN), CaF2, FA, calcium (Ca), and phosphorus (P) on/in enamel were determined. Data (log10-transformed) were subjected to ANOVA and the Student-Newman-Keuls’ test (p<0.05). Results We observed a dose-response relation between F concentrations in the gels without TMP for %SHR and ΔKHN. The 2.5% Nano and 5% Micro reached similar %SHR when compared with 9000F and Acid gels. For ΔKHN, Placebo and 5% Nano gels had the highest values, and 5% Micro, 2.5% Nano, 9000F, and Acid gels, the lowest. All groups had similar retained CaF2 values, except for Placebo and Acid gel. We verified observed an increase in Ca concentrations in nano-sized TMP groups. Regarding P, TMP groups showed similar formation and retention to 9000F and Acid. Conclusion Adding 2.5% nano-sized or 5% micrometric TMP to low-fluoride gels lead to enhanced in vitro remineralization of artificial caries lesions. (F nanosized nano sized respectively carieslike like n=168 n168 n 168 (n=168 SH (SH n=24/group n24group ngroup 24 group (n=24/group) F/TMP, FTMP F/TMP , F/TMP) 4500 4 500 4,50 4500F, (4500F) 25 2 5 2.5 (2.5 Nano) (5 Micro) 9000 9 000 9,00 (9000F) 12300 12 300 12,30 gel . gel) minute days loosely CaF firmlybound firmly bound fluorapatite (fluorapatite FA analysis %SHR, SHR (%SHR) ΔKHN (ΔKHN) Ca, (Ca) P (P onin determined log10transformed logtransformed log10 transformed log (log10-transformed StudentNewmanKeuls Student Newman Keuls Student-Newman-Keuls p<0.05. p005 p p<0.05 0 05 (p<0.05) doseresponse dose response values lowest lowfluoride low n=16 n16 16 (n=16 (n=24/group 450 50 4,5 (4500F 2. (2. ( 900 00 9,0 (9000F 1230 1 30 12,3 (%SHR (ΔKHN (Ca log1 p00 p<0.0 (p<0.05 n=1 n1 (n=1 45 4, (2 90 9, 123 3 12, p0 p<0. (p<0.0 n= (n= p<0 (p<0. (n p< (p<0 (p< (p