Plant extracts have dual mechanism on the protection against dentine erosion: action on the dentine substrate and modification of the salivary pellicle.

To investigate the effect of some polyphenol-rich plant extracts on the protection of dentine against demineralization, both acting on the dentine and on the salivary pellicle. Dentine specimens (n = 180) were randomly distributed into 6 experimental groups (n = 30/group): Control (deionized water), Açaí extract, Blueberry extract, Green tea extract, Grape seed extract, and Sn2+/F- (mouthrinse containing stannous and fluoride). Each group was further divided into two subgroups (n = 15), according to the site of action of the substance: on the dentine surface (D) or on the salivary pellicle (P). The specimens were submitted to 10 cycles: 30 min incubation in human saliva (P) or only in humid chamber (D), 2 min immersion in experimental substances, 60 min of incubation in saliva (P) or not (D), and 1 min erosive challenge. Dentine surface loss (DSL), amount of degraded collagen (dColl) and total calcium release were analyzed. Green tea, Grape seed and Sn2+/F- showed significant protection, with least DSL and dColl. The Sn2+/F- showed better protection on D than on P, whereas Green tea and Grape seed showed a dual mode of action, with good results on D, and even better on P. Sn2+/F- showed the lowest values of calcium release, not differing only from Grape seed. Sn2+/F- is more effective when acting directly on the dentine surface, while Green tea and Grape seed have a dual mode of action: with a positive effect on the dentine surface itself, but an improved efficacy in the presence of the salivary pellicle. We further elucidate the mechanism of action of different active ingredients on dentine erosion, where Sn2+/F- acts better on the dentine surface, but plant extracts have a dual mode of action, acting on the dentine itself as well as on the salivary pellicle, improving the protection against acid demineralization.

Dual protective effect of the association of plant extracts and fluoride against dentine erosion: In the presence and absence of salivary pellicle.

OBJECTIVES: To verify the protective effect of plant extracts associated with fluoride against dental erosion of dentine, in the presence and absence of a salivary pellicle. METHODS: Dentine specimens (n = 270) were randomly distributed into 9 experimental groups (n = 30/group): GT (green tea extract); BE (blueberry extract); GSE (grape seed extract); NaF (sodium fluoride); GT+NaF (green tea extract and NaF); BE+NaF (blueberry extract and NaF); GSE+NaF (grape seed extract and NaF); negative control (deionized water); and a positive control (commercialized mouthrinse containing stannous and fluoride). Each group was further divided into two subgroups (n = 15), according to the presence (P) or absence (NP) of salivary pellicle. The specimens were submitted to 10 cycles: 30 min incubation in human saliva (P) or only in humid chamber (NP), 2 min immersion in experimental solutions, 60 min of incubation in saliva (P) or not (NP), and 1 min erosive challenge. Dentine surface loss (dSL-10 and dSL-total), amount of degraded collagen (dColl) and total calcium release (CaR) were evaluated. Data were analyzed with Kruskal-Wallis, Dunn's and Mann-Whitney U tests (p>0.05). RESULTS: Overall, the negative control presented the highest values of dSL, dColl and CaR, and the plant extracts showed different degrees of dentine protection. For the subgroup NP, GSE showed the best protection of the extracts, and the presence of fluoride generally further improved the protection for all extracts. For the subgroup P, only BE provided protection, while the presence of fluoride had no impact on dSL and dColl, but lowered CaR. The protection of the positive control was more evident on CaR than on dColl. CONCLUSION: We can conclude that the plant extracts showed a protective effect against dentine erosion, regardless of the presence of salivary pellicle, and that the fluoride seems to improve their protection.

Synergistic effect between plant extracts and fluoride to protect against enamel erosion: An in vitro study.

Polyphenol-rich solutions, such as plant extracts and teas, can modify the salivary pellicle and improve the protection against dental erosion. In this study, we further explored how these polyphenol-rich plant extracts solutions behave in the presence of fluoride. We distributed enamel specimens into 9 groups (n = 15): Control_No_F- (Deionized water); Control_F- (500 ppm F-), Grape_Seed_No_F- (Grape seed extract), Grape_Seed_F- (Grape seed extract + 500 ppm F-), Grapefruit_Seed_No_F- (Grapefruit seed extract), Grapefruit_Seed_F- (Grapefruit seed extract + 500 ppm F-), Blueberry_No_F- (Blueberry extract), Blueberry_F- (Blueberry extract + 500 ppm F-), and Sn2+/F-_Rinse (commercial solution containing 800 ppm Sn2+ and 500 ppm F-). The specimens were submitted to 5 cycles (1 cycle per day), and each cycle consisted of: salivary pellicle formation (human saliva, 30 min, 37°C), modification of the pellicle (2 min, 25°C), pellicle formation (60 min, 37°C), and an erosive challenge (1 min, citric acid). Between cycles, the specimens were kept in a humid chamber. Relative surface hardness (rSH), relative surface reflection intensity (rSRI) and calcium released to the acid were analysed, using general linear models, and Kruskal-Wallis with post-hoc Dunn's tests. We observed that the presence of fluoride in synergy with the extract solutions provided better protection than the groups containing extract or fluoride only. For rSH, we observed a significant main effect of extracts (F(4,117) = 9.20; p<0.001) and fluoride (F(1,117) = 511.55; p<0.001), with a significant interaction (F(3,117) = 6.71; p<0.001). Grape_Seed_F- showed the best protection, better than fluoride, and Sn2+/F-_Rinse. Calcium results also showed greater protection for the groups containing fluoride, whereas for rSRI, despite a significant interaction between extract and fluoride (F(3,117) = 226.05; p<0.001), the differences between the groups were not as clearly observed. We conclude that polyphenols from plant extracts, when combined with fluoride, improve the protective effect of salivary pellicles against enamel erosion.

Pellicle modification with natural bioproducts: Influence on tooth color under erosive conditions.

Salivary pellicle was modified with bioproducts and we assessed the change in tooth color and the protection of enamel to erosion. Human enamel specimens were assigned to one of three solutions: grape seed extract or black tea (bioproducts), or deionized water (negative control); after which one half the specimens underwent erosive challenges. The specimens underwent 15 cycles involving salivary pellicle formation (10 min, 37°C), incubation in solution (2 min, 25°C), subsequent pellicle formation (90 min, 37°C). Half of the specimens was kept in a humid chamber and the other half was submitted to erosion (2 min, 1% citric acid). After 15 such cycles, the pellicle was removed. Tooth color and the surface reflection intensity were assessed after every five cycles and after pellicle removal. For non-eroded specimens, the exposure to bioproducts promoted significantly greater color change than the deionized water, with increases in yellow appearance. After pellicle removal, the color was similar in all non-eroded specimens. The bioproducts increased the surface reflection intensity over cycles. For the erosion-exposed specimens, erosion itself resulted in color change. Black tea and deionized water resulted in increased yellow appearance. Exposure to the bioproducts resulted in higher relative surface reflection intensity values over time, but only grape seed extract resulted in higher relative surface reflection intensity value at the time of pellicle removal. The bioproducts caused transient staining effect, which was reduced after pellicle removal. For enamel submitted to erosion, grape seed extract resulted in less color change and better protection of enamel against erosion than black tea or water.

Salivary Pellicle Modification with Grape-seed Extract: In Vitro Study on the Effect on Bacterial Adhesion and Biofilm Formation.

PURPOSE: Grape-seed extract (GSE) contains polyphenols that readily adhere to proteins and modify the acquired enamel pellicle (AEP). The first step in biofilm formation is bacterial adhesion to the AEP-covered enamel. The aim of this in vitro study was to test whether AEP modification with GSE, fluoride (F-), or their combination (GSE+F-) modulates bacterial adhesion, biofilm metabolism and composition, or cariogenic demineralisation of the enamel. MATERIALS AND METHODS: The study comprised 3 parts: 1) single-strain Streptococcus gordonii species, 2) a five-species biofilm model, or 3) biofilm (re-)formation using the five-species biofilm model after removal of initial biofilm with toothbrushing. Human whole-mouth stimulated saliva was used to form an AEP on human enamel specimens. The AEP was incubated in water (control), or modified with GSE, F-, or GSE+F-. Bacterial adhesion, biofilm diversity, metabolic activity, biofilm mass, and cariogenic demineralisation (surface hardness) of enamel were assessed after incubation in bacterial broths after 4 h or 22 h. Differences between groups were analysed with one-way ANOVA and post-hoc Bonferroni tests. RESULTS: GSE and GSE+F- statistically significantly decreased single-strain S. gordonii adhesion, but had no relevant influence when the five-species biofilm model was used. In the biofilm (re-)formation model, GSE reduced bacterial adhesion compared to GSE+F-, while F- caused less cariogenic demineralisation than was found in the control group. CONCLUSION: AEP modified with GSE retards S. gordonii adhesion, but it does not influence the formation, metabolism and composition of a cariogenic multi-species biofilm.

Salivary pellicle modification with polyphenol-rich teas and natural extracts to improve protection against dental erosion.

OBJECTIVE: To investigate the modification of the salivary pellicle with different polyphenol-rich teas and natural extracts for the protection against dental erosion. METHODS: We performed two experiments: one with teas (Green tea, Black tea, Peppermint tea, Rosehip tea, negative control [NC]) and other with natural extracts (Grape seed, Grapefruit seed, Cranberry, Propolis, NC), where NC was deionized water. A total of 150 enamel specimens were used (n = 15/group). Both experiments followed the same design, consisting of 5 cycles of: salivary pellicle formation (30 min, 37 °C), modification with the solutions (30 min, 25 °C), further salivary pellicle formation (60 min, 37 °C) and erosive challenge (1 min, 1% citric acid, pH 3.6). Relative surface microhardness (rSMH), relative surface reflection intensity (rSRI) and amount of calcium release (CaR) were evaluated. Data were analysed with Kruskal-Wallis and Wilcoxon rank sum tests with Bonferroni correction (α = 0.05). RESULTS: Regarding teas, Black and Green teas showed the best protection against dental erosion, presenting higher rSMH and lower CaR than NC. Peppermint tea was not different to NC and Rosehip tea caused erosion, showing the highest CaR and greatest loss of SMH and SRI. Regarding natural extracts, Grape seed and Grapefruit seed extracts presented the best protective effect, with significantly higher rSMH and lower CaR. Cranberry caused significantly more demineralization; and Propolis did not differ from NC. CONCLUSION: Green tea, Black tea, Grape seed extract and Grapefruit seed extract were able to modify the salivary pellicle and improve its protective effect against enamel erosion, but Rosehip tea and Cranberry extract caused erosion. CLINICAL RELEVANCE: Some some bio-products, such as teas and natural extracts, improve the protective effect of the salivary pellicle against enamel erosion. More studies should be performed in order to test the viability of their use as active ingredients for oral care products.