Remineralization and protection from demineralization: effects of a hydroxyapatite-containing, a fluoride-containing and a fluoride- and hydroxyapatite-free toothpaste on human enamel in vitro

Abstract

Background The aim was to evaluate the remineralization potential as well as the extent of protection against renewed demineralization of enamel by hydroxyapatite-containing toothpaste (Karex) in comparison to fluoride-containing (Elmex) and fluoride- and hydroxyapatite-free toothpaste (Ajona) as control. Methods Fifty-seven enamel samples were obtained from 19 human teeth. Five demarcated surfaces were created on each tooth (S0—S4). Four of the surfaces (S1—S4) were exposed to lactic acid (pH 3) for 8 h (demineralization). S0 was left untreated as control. S1 was solely treated with acid. After demineralization, S2 was exposed to Karex for 2 min, of which 15 s were brushing. S3 was treated with Elmex and S4 with Ajona, accordingly. Then, the samples were evaluated using a scanning electron microscope and ImageJ image analysis software to determine the percentage of demineralization. Afterwards, S2-S4 were again exposed to lactic acid for 2 h, and subjected to pixel analysis another time. Data were statistically analysed using ANOVA with post-hoc Scheffé test and the Kurskal-Wallis test. Results The surfaces treated with Elmex showed the lowest percentage of demineralization (mean 5.01 ± 0.98%) (p < 0.01). Thus, Elmex remineralized more effectively compared to Ajona (8.89 ± 1.41%) and Karex (9.85 ± 1.63%) (p < 0.01). Furthermore, Elmex showed the lowest percentage of demineralized enamel after new demineralization (median 6.29%), followed by Ajona (11.92%) and Karex (13.46%) (p < 0.001). Conclusion In terms of remineralization and protection against renewed demineralization, a hydroxyapatite-containing toothpaste (Karex) appears to be inferior to a fluoride-containing toothpaste (Elmex) and a fluoride- and hydroxyapatite-free toothpaste (Ajona). Hence, the recommendation to use Karex to protect against demineralization should be critically questioned.

Protective effect of various toothpastes and mouthwashes against erosive and abrasive challenge on eroded dentin: an in vitro study

“…However, its independent protective effect against erosion is not yet clearly defined 15 . Hydroxyapatite-containing toothpaste showed the lowest percentage of remineralization and protection effect against subsequent demineralization compared to AmF-containing toothpaste and fluoride- and hydroxyapatite-free toothpastes 16 . nHA also showed the least remineralizing properties compared to CPP-ACPF and bioactive glass on eroded enamel lesions 14 .…”

“…Various compounds, including fluoride 3 , 7 , 9 – 11 , casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) 11 – 14 , nanohydroxyapatite (nHA) 11 , 14 – 16 , chitosan 17 , 18 , and protease inhibitors 7 , 19 have been used in the forms of toothpaste, mouth rinse, gel, and varnish to prevent tooth erosion progression and alleviate hypersensitivity. Different forms of fluoride, including sodium fluoride (NaF), amine fluoride (AmF), monofluorophosphate (MFP), and stannous fluoride (SnF 2 ) with different concentrations and pH levels, have demonstrated a significant reduction in enamel dissolution and an increase in resistance to acid attacks by deposition of protective calcium fluoride layer on the tooth surface 9 .…”

Effect of treatment with phosphate, casein phosphopeptide and fluoride on the remineralization: in vitro study

“…For hardness measurements, a section was made in the center of each block, and one of the halves was embedded in acrylic resin and gradually polished. One sequence of 14 indentations was created at different distances (5,10,15,20,25,30,40,50,70,90,110,130,220, and 330 μm) from the surface of the enamel, in the central region of the blocks, using a Micromet 5114 hardness tester (Buehler ) with a Knoop diamond indenter under a 5 g load for 10 s. Integrated hardness (KHN × μm) for the lesion into sound enamel was calculated by the trapezoidal rule (GraphPad Prism, version 3.02) and subtracted from the integrated hardness for sound enamel to obtain the integrated area of the subsurface regions in the enamel, obtaining the integrated loss of subsurface hardness (∆KHN; KHN × μm). 9,22 Analysis of the profile and depth of subsurface lesions using polarized light microscopy After cross-sectional hardness analysis, the enamel blocks (n = 12/group) embedded in acrilyc resin were sectioned to obtain slices of 300 µm and ground to a thickness of ~100 um using 400 grit paper (Paper Discs,30-5108-320, Buehler) at grinder polisher (Phoenix Beta with Vector Powerhead, Buehler), under constant water refrigeration.…”

“…4 Thus, it functions as a source of F, thereby interfering with the dynamics of the de-remineralization processes. 5 To maximize the clinical significance of remineralization, a number of preventive agents in some studies have shown successes in using P, Ca ions associated with F on the tooth surface, assisting in enamel remineralization. 3,6,7 The performance of dairy products, as a topical anticariogenic effect, has been noted since the 1980s.…”

Assessment of the Remineralizing Potential of Biomimetic Materials on Early Artificial Caries Lesions after 28 Days: An In Vitro Study

“…A number of studies suggest that fluoride (F) remains the best established agent to promote remineralization [ 8 , 9 ]. This is attributed both to the fluoride-enhanced precipitation into the tooth enamel of Ca 2+/ PO 4 3− and to the formation of fluorohydroxyapatite (F-HA) [ 10 ].…”