Development of TiF4-Dendrimer complex gel as an anti-demineralization agent for dentin: An in vitro study

OBJECTIVE

The anti-caries effects of titanium tetrafluoride (TiF4) are well-documented, but its low pH challenges clinical application. This study evaluated PEG-citrate dendrimer as a carrier to enhance TiF4 stability and efficacy.

METHODS

PEG-citrate dendrimer and TiF4-dendrimer gel were synthesized, and their structures confirmed using Fourier Transform Infrared Spectroscopy (FTIR), Hydrogen Nuclear Magnetic Resonance (1H NMR), and Liquid Chromatography-Mass Spectrometry (LC-MS). Thirty-six intact human teeth were prepared, randomly divided into three groups (n = 12) and subjected to pH cycling with the following treatments: titanium tetrafluoride (T), dendrimer (D), and dendrimer with TiF4 (TD). Vickers microhardness and Raman spectroscopy evaluated dentin demineralization. EDS analysis measured titanium and fluoride penetration into dentin in T and TD groups and mineral content (calcium and phosphorus) in all groups.

RESULTS

The T group showed the highest microhardness loss (p < 0.001), followed by D and TD groups. EDS analysis revealed no significant difference in titanium and fluoride content between the surface and subsurface in TD (p = 0.344), while T had more titanium on the surface (p < 0.001). TD had higher subsurface calcium content compared to T (p = 0.008). Raman spectroscopy revealed significant changes in phosphate-to-amide and carbonate-to-amide ratios before and after pH cycling in all groups (p < 0.001), with no statistical differences among the groups.

CONCLUSION

Using dendrimer as a carrier for TiF4 increased pH and enhanced TiF44 ability to limit dentin demineralization and microhardness loss.

CLINICAL RELEVANCE

The application of the newly-developed TiF4-dendrimer gel might be an effective approach to prevent/ limit dentin demineralization and dentin caries.

Efficacy and safety of TiF4 varnish in preventing erosive tooth wear in a rat animal model

An animal model was applied to develop erosive tooth wear (ETW) and to evaluate the efficacy and safety of titanium tetrafluoride (TiF4) in preventing ETW. Forty-eight male Wistar rats were divided into three groups (n = 16): TiF4 (2.45% F-), NaF (2.45% F-) and placebo varnishes. Eight from each group were subjected to erosive challenges (Sprite Zero) and the other received tap water, both ad libitum. After twenty-eight days, the mandibles were resected for histopathological gingival analysis, clinical and microscopic tooth evaluation by 3D confocal laser microscopy, scanning electron microscopy (SEM-EDX) and micro-Raman spectroscopy (MRS). Organs were evaluated with respect to fluoride content. No significant difference was found in F content in tissues. No histopathological damage was seen in gingiva. ETW was clinically more aggressive in rats from placebo group consuming Sprite compared to water (Q²=12.6, p < 0.01), in accordance with confocal images. TiF4 was superior in reducing cross-section area loss (0.036 ± 0.01µm2) compared to NaF and placebo, respectively (0.044 ± 0.01/0.063 ± 0.01µm2, ANOVA, p < 0.0001). Dentin exposure was detected by SEM in rats belonging to placebo consuming Sprite. Peaks compatible with typical apatite bands were visible. TiF4 reduces the progression of ETW without causing any relevant side-effect and the rats' model was able to simulate ETW in vivo.

Effect of an experimental TiF4/NaF solution in preventing tooth erosion

OBJECTIVE

This was a randomized, double-blind, parallel, placebo-controlled in vivo study investigating the protective potential of a titanium tetrafluoride/ sodium fluoride (TiF4/NaF) solution compared to its respective positive and negative controls under an in vivo model, as well as the perception of participants regarding the use of this experimental solution.

METHODS

After the ethics approval and the selection procedures, 33 participants were divided into three treatments: TiF4/NaF solution (500 ppm F, pH 4.4); AmF/NaF/SnCl2-mouthwash (500 ppm F, pH 4.5) and water (pH 7.0) (n = 11). After professional cleaning, the participants rinsed with one of the solutions for one minute and waited two hours for the erosive challenge. The erosive solution (1 % citric acid, pH 2.5) was applied for 10 s on each central incisor (enamel area: 4 mm2) and collected for calcium analysis using III Arsenazo colorimetric method. The Ca2+ release data were compared using Kruskal-Wallis/ Dunn tests (p < 0.05).

RESULTS

Teeth treated with both fluoride solutions released less calcium into the acid (median and interquartile interval: TiF4/NaF - 0.45/0.19 mM and AmF/NaF/SnCl2 - 0.46/0.15 mM Ca2+, p = 0.99) compared to the negative control (1.12/0.42 mM Ca2+, 60 % reduction, p < 0.0006). For both F solutions, only one participant per group reported unpleasant taste. Four participants belonging to AmF/NaF/SnCl2-mouthwash reported burning sensation post-rinse, while only one participant described such feeling after TiF4/NaF rinsing.

CONCLUSION

The experimental TiF4/NaF solution was as effective as the commercial AmF/NaF/SnCl2-mouthwash in protecting enamel against erosive demineralization with a good acceptability by the participants.

Tooth Age Impact on Dental Erosion Susceptibility and Treatment Efficacy

This laboratory study investigated the impact of tooth age on dental erosion susceptibility and preventive treatment efficacy. Extracted human premolars were selected and had their age estimated (∼10-100 years old) using established dental forensic methods. Enamel and root dentin slabs were prepared, embedded in acrylic blocks, flattened, and polished. The specimens were randomly assigned to one of three treatments (n = 93): Sn+F (800 ppm Sn as SnCl2 and 250 ppm F as NaF, pH 4.5), NaF (250 ppm F, pH 4.5), or deionized water (DIW). Each specimen was subjected for 10 days to a daily cycling protocol consisting of six 5-min erosive challenges (0.3% citric acid, pH 2.6), six 60-min remineralization periods (artificial saliva), and three 2-min treatments with the test solutions. Surface loss (SL) was measured after 3, 5, and 10 days, using optical profilometry. Effects of tooth age, antierosive treatment, and time on SL were evaluated using linear mixed effects regression analysis. SL increased with age for all substrate-treatment-time combinations (p < 0.0001). Sn+F and NaF solutions significantly reduced SL compared to DIW, regardless of substrate, time, or age (p < 0.0001), with best results shown for Sn+F. Efficacy of Sn+F increased with tooth age on enamel, but tooth age did not affect the efficacy of NaF on enamel. For dentin, increased efficacy was observed with age after 5 (for Sn+F) and 10 days (for Sn+F and NaF). In conclusion, increase of tooth age rendered enamel and root dentin more susceptible to dental erosion. NaF preventive efficacy improved with tooth age for dentin, in advanced erosion simulation. Sn+F reduced enamel SL due to erosion regardless of tooth age.

Effect of TiF4/NaF and chitosan solutions on the development of enamel caries under a microcosm biofilm model

OBJECTIVES

To evaluate the effect of experimental solutions containing TiF₄/NaF and chitosan on bacterial species and on enamel caries prevention.

METHODS

Microcosm biofilm was produced from human saliva mixed with McBain saliva (0.2% sucrose) on bovine enamel for five days, under 5% CO₂ and 37 °C. From the second day until the end, the treatments were applied (1 × 60 s/day): (1) NaF (500 ppm F^-, positive control); (2) TiF₄ and NaF (TiF₄: 190 ppm Ti⁴⁺ and 300 ppm F^-; NaF: 190 ppm F^-); (3) similar to 2 plus 0.5% chitosan (Ch 500 mPas, 75% deacetylation); (4) phosphate buffer solution (negative control); and (5) 0.5% chitosan (Ch 500 mPas, 75% deacetylation). CFU counting was performed for total microorganism, total streptococcus, total lactobacillus and Streptococcus mutans. Enamel demineralization was measured by transverse microradiography-TMR. The data were compared using ANOVA/Tukey or Kruskal-Wallis/Dunn tests (p < .050).

RESULTS

No differences were found between the treatments with respect to CFU counting (ANOVA, p > .050). Enamel treated with TiF₄/NaF plus chitosan solution presented the lowest demineralization compared to the negative control and pure chitosan solution. On the other hand, this experimental solution did not significantly differ from TiF₄/NaF and NaF solutions, being all of them able to significantly reduce mineral loss (50-74%), but only TiF₄/NaF plus chitosan reduced lesion depth (55%) compared to the negative control (p = .001).

CONCLUSION

TiF₄/NaF plus chitosan solution had no antimicrobial effect, but it was able to reduce enamel caries development in 79% compared to control under this model.

CLINICAL SIGNIFICANCE

This study showed that TiF₄/NaF plus chitosan solution had no antimicrobial effect, but it was able to reduce enamel caries development under a microcosm biofilm model.

Effect of TiF4 varnish after pre-treatment with proanthocyanidin or chlorhexidine on the progression of erosive dentin loss in the presence or absence of the demineralized organic matrix

This study evaluated the protective effect of TiF₄ varnish, after pre-treatment with proantocyanidin or chlorhexidine, on the progression of erosive dentin loss (EDL), under the presence or absence of the demineralized organic matrix (DOM). Bovine root dentin samples were eroded for 30 min (0.1% citric acid, pH 2.5) and the loss was measured by profilometry. Half of them were subjected to the DOM removal using collagenase for 4 days, while the other half remained immersed in water. The removal of DOM was checked by profilometry. Samples were divided into 24 groups (n = 15) according to the factors: 1- With or without DOM; 2- Pre-treatment with 0.012% chlorhexidine gel, 10% proanthocyanidin gel or untreated for 1 min; 3-Final Treatment with TiF₄ varnish, NaF varnish, placebo varnish or untreated for 6 h. The samples were submitted to a pH cycling for 5 days: 0.1% citric acid (4 × 90s/day) and artificial saliva between the challenges. The final profile was obtained for the calculation of EDL (μm, three-way ANOVA/Tukey test). When DOM was preserved, the EDL was lower compared to the condition without DOM (7.08 ± 4.03 μm and 9.80 ± 3.79 μm, p < 0.001, respectively), regardless of the treatments. The pre-treatment had no influence on the progression of EDL (p = 0.637), while the final treatment (TiF₄ varnish only, 6.77 ± 4.08 μm) was effective in reducing the progression of EDL (NaF varnish: 9.52 ± 4.02 μm; Placebo varnish: 8.64 ± 4.06 μm and no treatment: 8.80 ± 3.95 μm). It can be concluded that DOM has important protective effect on the progression of EDL. TiF₄ was the unique treatment capable of reducing EDL progression, regardless of the pre-treatment of DOM.

Quercetin reduces erosive dentin wear: Evidence from laboratory and clinical studies

OBJECTIVE

The aim of the present study was to evaluate the effect of quercetin on the acid resistance of human dentin through both laboratory and clinical studies.

METHODS

Two hundred and twelve dentin blocks (2 mm × 2 mm × 2 mm) were prepared and used. For the laboratory study, dentin specimens were randomly divided into 8 groups (n = 12): deionized water, ethanol, 1.23 × 10⁴ μg/ml sodium fluoride (NaF), 120 μg/ml chlorhexidine, 183.2 μg/ml epigallocatechin gallate (EGCG), and 75 μg/ml, 150 μg/ml, and 300 μg/ml quercetin (Q75, Q150, and Q300). The specimens were treated with the respective solutions for 2 min and then subjected to in vitro erosion (4 cycles/d for 7 d). The surface microhardness loss (%SMH_l), erosive dentin wear, and surface morphology were evaluated and compared. For the impact on MMP inhibition, the release of crosslinked carboxyterminal telopeptide of type I collagen (ICTP) and the thickness of the demineralized organic matrix (DOM) were measured using additional dentin specimens. For the clinical study, the specimens were treated with NaF or Q300 for 2 min and then subjected to in vivo erosion (4 cycles/d for 7 d). The %SMH_l and erosive dentin wear of the specimens were measured to determine whether quercetin similarly inhibits erosion in situ.

RESULTS

The quercetin-treated group had a significantly lower %SMH_l and erosive dentin wear than any other group, and the effect was concentration-dependent in vitro (P < 0.05). Dentin treated with quercetin produced significantly less ICTP and had a thicker DOM than the control dentin (P < 0.05). After in vivo erosion, the %SMH_l and erosive dentin wear of the Q300 group were significantly lower than those of the control group (P < 0.05).

SIGNIFICANCE

The application of quercetin was shown, for the first time, to increase the acid resistance of human dentin, possibly through MMP inhibition and DOM preservation.

Effect of different citrus sweets on the development of enamel erosion in vitro

The increased consumption of citrus sweets can contribute to the development of erosive tooth wear (ETW).

Morphological and chemical effects of in-office and at-home desensitising agents containing sodium fluoride on eroded root dentin

OBJECTIVE

The aim of this study was to evaluate the morphological and chemical effect of in-office and at-home desensitising agents containing sodium fluoride (NaF) on eroded root dentine in vitro.

METHODS

Fifty bovine dentine samples were pre-eroded and randomised into five groups (n = 10): G1 (Control) - milli-Q water; G2 - fluoride varnish containing NaF 22,500 ppm; G3 - desensitising cream containing NaF 9,000 ppm associated with 20% nanohydroxyapatite; G4 - toothpaste with NaF 5,000 ppm associated to tricalcium phosphate; G5 - toothpaste containing NaF 900 ppm and casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACPF). The specimens were submitted to erosive challenge for three days. The analyses were performed using non-contact profilometry for volumetric (Sa) and linear roughness (Ra) followed by scanning electron microscopy (SEM) and Energy Dispersive X-ray Spectrometry (EDS). The data were analysed by Kruskal-Wallis and Wilcoxon tests (α = 0.05).

RESULTS

There was a significant reduction of Ra and Sa for the eroded samples from the G2 and G5 (p < 0.05) after an erosive challenge. The dentine surface topography pattern showed partially or totally occluded dentinal tubules after treatments, except in the control group. The control, G4 and G3 groups showed a reduction in the dentine inorganic content percentage of Ca (Calcium) and P (Phosphorus) minerals.

CONCLUSION

The fluoride varnish and CPP-ACPF toothpaste were able to prevent morphological changes and were the only materials that showed the Ca and P content increased after treatment. These materials may be promising alternatives in the clinical control of dentin erosion.

Protective Effect of 4% Titanium Tetrafluoride Varnish on Dentin Demineralization Using a Microcosm Biofilm Model

This study evaluated the effect of titanium tetrafluoride (TiF4) varnish on the development of dentin carious lesions. Bovine root dentin samples were treated for 6 h with: (A) 4% TiF4 varnish (2.45% F); (B) 5.42% sodium fluoride (NaF) varnish (2.45% F); (C) 2% chlorhexidine (CHX) gel – positive control; (D) placebo varnish; or (E) untreated – negative control (n = 4 × biological triplicate, n = 12). Treated dentin samples were exposed to human saliva mixed with McBain saliva (1:50) for the first 8 h in 24-well plates. Thereafter, the medium was removed, and McBain saliva containing 0.2% sucrose was applied for 16 h. From days 2 to 5, McBain saliva with sucrose was replaced daily (37°C, 5% CO2). The demineralization was measured using transverse microradiography, while the effect on biofilm was analyzed using viability, extracellular polysaccharide (EPS), and lactic acid production assays. The data were statistically analyzed (p < 0.05). All treatments (fluorides and CHX) significantly reduced the biofilm viability compared to placebo varnish and negative control. However, none of them was able to reduce the colony-forming unit counting for total microorganism, total streptococci, and Streptococcus mutans. NaF significantly reduced the number of Lactobacillus sp. compared to negative control. No effect was seen on lactic acid production neither on EPS synthesis, except that CHX significantly reduced the amount of insoluble EPS. Both fluorides were able to reduce dentin demineralization compared to placebo varnish and negative control; TiF4 had a better effect in reducing mineral loss and lesion depth than NaF. Therefore, TiF4 varnish has the best protective effect on dentin carious lesion formation using this model.