Remineralizing effect of NSF on artificial enamel caries.

INTRODUCTION: Nanotechnology offers new approaches and endless opportunities for remineralizing tooth decay without being toxic or causing allergies. This study aimed to determine the effect of nanosilver fluoride (NSF) on the remineralization potential of enamel caries-like lesions compared to 5% sodium fluoride varnish in permanent teeth. METHODS: Fifteen teeth (molars and premolars) were gathered, cleaned, and polished using a scaler. After sectioning the teeth mesiodistally and removing the roots, the thirty specimens were subjected to a demineralized solution to induce early enamel lesions and then assigned randomly into two equal groups. The test materials were applied, and then all the specimens were subjected to a pH cycling model for 30 days. DIAGNOdent and surface roughness were investigated, and an evaluation of the enamel Ca and P weight% for Ca/P ratio calculation was done using SEM-EDX to analyze the specimens at the end of the study. The data were analyzed using an independent t-test. RESULTS: The mean values for the DIAGNOdent measurements for NSF and NaF at baseline and after demineralization were not significantly different (p > 0.05). After treatment, NaF varnish showed a significantly higher mean DIAGNOdent measurement (11.8 ± 5.80) than NSF (4.7 ± 1.6). The mean surface roughness of the NaF group (1.64 ± 0.39) was much higher than NSF's mean surface roughness (1.07 ± 0.21). Specimens treated with NSF had statistically significant smoother surfaces (p < 0.001). The NSF group had a higher mean Ca/P ratio (2.9 ± 0.35) than NaF (2.2 ± 0.11). This difference was statistically significant (p = 0.012). CONCLUSION: The study reveals that nano silver fluoride is a more effective treatment than sodium fluoride varnish in enhancing teeth's clinical characteristics, particularly in terms of mineral content and surface roughness, suggesting it could be an improved strategy to prevent dental caries and maintain enamel integrity.

The damage and remineralization strategies of dental hard tissues following radiotherapy.

OBJECTIVES: This study pursued two main purposes. The first aim was to expound on the microscopic factors of radiation-related caries (RRC). Further, it aimed to compare the remineralization effect of different remineralizing agents on demineralized teeth after radiotherapy. METHODS: The enamel and dentin samples of bovine teeth were irradiated with different doses of radiation. After analysis of scanning electron microscope (SEM), X-Ray diffraction (XRD), and energy dispersive spectrometer (EDS), the samples irradiated with 50 Gy radiation were selected and divided into the demineralization group, the double distilled water (DDW) group, the Sodium fluoride (NaF) group, the Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) group, the NaF + CPP-ACP group, and the Titanium tetrafluoride (TiF4) group. After demineralization, remineralizing agents treatment, and remineralization, the samples were evaluated using SEM, atomic force microscope (AFM), EDS, and transverse microradiography (TMR). RESULTS: A radiation dose of 30 Gy was sufficient to cause damage to the dentinal tubules, but 70 Gy radiation had little effect on the microstructure of enamel. Additionally, the NaF + CPP-ACP group and the TiF4 group significantly promoted deposit formation, decreased surface roughness, and reduced mineral loss and lesion depth of demineralized enamel and dentin samples after radiation. CONCLUSIONS: Radiation causes more significant damage to dentin compared to enamel. NaF + CPP-ACP and TiF4 had a promising ability to promote remineralization of irradiated dental hard tissues. ADVANCES IN KNOWLEDGE: This in vitro study contributes to determining a safer radiation dose range for teeth and identifying the most effective remineralization approach for RRC.

Dentin erosive wear is reduced by fluoride varnishes containing nanosized sodium trimetaphosphate in vitro.

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.

Evaluation of the remineralization potential of self-assembling peptide P11-4 with fluoride compared to fluoride varnish in the management of incipient carious lesions: a randomized controlled clinical trial.

OBJECTIVES: The present trial's aim was to compare the remineralization potential of self-assembling peptide P11-4 combined with fluoride to that of fluoride varnish. MATERIALS AND METHODS: Twenty-eight participants with 58 incipient carious lesions were enrolled in the present trial. Participants were randomly divided into two groups with 14 participants and 29 incipient lesions in each group. Patients were assigned either to self-assembling peptide combined with fluoride (Curodont Repair Fluoride Plus™) or sodium fluoride varnish (NaF, Bifluorid 10) groups. Both agents were applied according to the manufacturer's instructions on non-cavitated incipient carious lesions. Lesions were assessed by two calibrated and blinded assessors at baseline, and after one-, three- and six-months using a laser fluorescence device (DIAGNOdent). RESULTS: Although laser fluorescence scores significantly improved in both groups over time (p < 0.05), no notable differences were evident between both groups at one-month (p > 0.05). Yet, at three- and six-months statistically lower laser fluorescence readings were evident in the self-assembling peptide combined with fluoride group in comparison to the fluoride alone group (p < 0.05). There was 60% less risk for caries progression for Curodont Repair Fluoride Plus™ when compared to NaF varnish after six months. Self-assembling peptide combined with fluoride was able to change 65.5% of non-cavitated carious lesions from DIAGNOdent score 3 (11-20) to score 1 (0-4). Fluoride varnish was able to change 13.8% of the lesions from score 3 to score 1 after six months. CONCLUSIONS: The self-assembling peptide combined with fluoride varnish showed higher remineralization potential than fluoride varnish alone for incipient carious lesions over a six-months follow up. CLINICAL RELEVANCE: The combination of self-assembling peptide P11-4 and fluoride could offer a new tool in managing incipient carious lesions.

Epigallocatechin-3-gallate attenuates fluoride induced apoptosis via PI3K/FoxO1 pathway in ameloblast-like cells.

Fluoride is a double-edged sword. It was widely used for early caries prevention while excessive intake caused a toxicology effect, affected enamel development, and resulted in dental fluorosis. The study aimed to evaluate the protective effect and mechanism of Epigallocatechin-3-gallate (EGCG) on the apoptosis induced by fluoride in ameloblast-like cells. We observed that NaF triggered apoptotic alterations in cell morphology, excessive NaF arrested cell cycle at the G1, and induced apoptosis by up-regulating Bax and down-regulating Bcl-2. NaF activated the insulin-like growth factor receptor (IGFR), and phosphatidylinositol-3-hydroxylase (p-PI3K), while dose-dependently down-regulating the expression of Forkhead box O1 (FoxO1). EGCG supplements reversed the changes in LS8 morphology, the cell cycle, and apoptosis induced by fluoride. These results indicated that EGCG possesses a protective effect against fluoride toxicity. Furthermore, EGCG suppressed the activation of p-PI3K and the down-regulation of FoxO1 caused by fluoride. Collectively, our findings suggested that EGCG attenuated fluoride-induced apoptosis by inhibiting the PI3K/FoxO1 signaling pathway. EGCG may serve as a new alternative method for dental fluorosis prevention, control, and treatment.

Fluoride induces immunotoxicity by regulating riboflavin transport and metabolism partly through IL-17A in the spleen.

The impairment of the immune system by fluoride is a public health concern worldwide, yet the underlying mechanism is unclear. Both riboflavin and IL-17A are closely related to immune function and regulate the testicular toxicity of fluoride. However, whether riboflavin or IL-17A is involved in fluoride-induced immunotoxicity is unknown. Here, we first established a male ICR mouse model by treating mice with sodium fluoride (NaF) (100 mg/L) via the drinking water for 91 days. The results showed that fluoride increased the expression of the proinflammatory factors IL-1ß and IL-17A, which led to splenic inflammation and morphological injury. Moreover, the expression levels of the riboflavin transporters SLC52A2 and SLC52A3; the transformation-related enzymes RFK and FLAD1; and the key mitochondrial functional determinants SDH, COX, and ATP in the spleen were measured via real-time PCR, Western blotting, and ELISA. The results revealed that fluoride disrupted riboflavin transport, transformation, metabolism, and mitochondrial function. Furthermore, wild-type (WT) and IL-17A knockout (IL-17A-/-) C57BL/6 J male mice of the same age were treated with NaF (24 mg/kg·bw, equivalent to 100 mg/L) and/or riboflavin sodium phosphate (5 mg/kg·bw) via gavage for 91 days. Similar parameters were evaluated as above. The results confirmed that fluoride increased riboflavin metabolism through RFK but not through FLAD1. Fluoride also affected mitochondrial function and activated neutrophils (marked with Ly6g) and macrophages (marked with CD68) in the spleen. Interestingly, IL-17A partly mediated fluoride-induced riboflavin metabolism disorder and immunotoxicity in the spleen. This work not only reveals a novel toxic mechanism for fluoride but also provides new clues for exploring the physiological function of riboflavin and for diagnosing and treating the toxic effects of fluoride in the environment.

An SEM study on the effect of 9.3-µm CO2 laser on dentinal tubules for hypersensitivity treatment.

OBJECTIVES: In-vitro studies were performed on dentin of extracted human molars to investigate the effectiveness of 9.3 µm CO2 laser irradiation to occlude dentinal tubules. The observed occlusion of dentinal tubules with the irradiation was compared with application of three reagents: 2% Sodium Fluoride gel, an aqueous solution of hydroxyapatite nanoparticles and an equal mix of the two. We show that 9.3 µm CO2 laser irradiation occludes dentinal tubules, and the use of laser irradiation produces better occlusion of the opened tubules compared to the use of topical reagents. METHODS: Nine extracted and cleaned human molars were cut to obtain dentin disks of thickness of 3-5 mm. Each disc was divided into four quarters, and each quarter served as two samples corresponding to irradiated and non-irradiated group counterparts. Five disks were used to study the effect of various laser irradiation energies on the dentinal tubules to find a good pulse fluence for occlusion of the dentinal tubules, and four disks were used for studying the effects of reagents and irradiation at the pulse fluences found in the first part of the study. The samples were irradiated with a beam diameter of 1 mm (1/e2) at 15 Hz pulse repetition rate, scanned automatically using a set of scanning mirrors. Samples were imaged using Scanning Electron Microscope (SEM) which were processed to determine tubule diameter. Safety of the irradiation treatment was investigated on 6 samples by measuring pulpal temperature rise. The effect of three topical reagents corresponding to 2% Sodium Fluoride gel (F), Hydroxyapatite nanoparticles (HA) and an equal mix of F and HA (HAF) on dentinal tubule occlusion was evaluated and compared with the laser irradiation. RESULTS: In all examined cases, laser irradiation at a fluence of 0.81 J/cm2 resulted in a temperature increase less than 3 °C which is safe, and no surface cracking was observed. There is a threshold pulse fluence of 0.27 J/cm2 above which, laser produced surface melting. At a pulse fluence of 0.81 J/cm2 a layer of recast of melted dentin was formed. Under this layer, peritubular dentin melting and occluding of the dentinal tubules was observed. Application of either F or HA or HAF did not produce visible occlusion effect on open tubules after washing and microbrushing with excess distilled water. CONCLUSIONS: 9.3 µm CO2 laser irradiation on extracted human molar dentin at pulse fluence of 0.81 J./cm2 resulted in tubule area reduction by 97% without rising pulpal temperatures to unsafe levels.

Inorganic Phosphate Effect in a Hydrogen Peroxide-based Bleaching Agent: Physicochemical, Mechanical, and Morphological Properties of Dental Enamel.

OBJECTIVES: This in vitro study aimed to assess the impact of incorporating calcium glycerophosphate (CaGP) and sodium fluoride (NaF) in addition to 35% hydrogen peroxide concerning the enamel mechanical and morphological properties. METHODS: Specimens of bovine enamel were chosen based on their initial surface hardness (SHi) and subsequently divided into five gel groups (n=12): 1) 35% Hydrogen Peroxide (HP) Gel; 2) HP + 0.1% NaF Gel (HP/NaF); 3) HP + 0.25% CaGP Gel (HP/CaGP); 4) HP + 0.1% NaF + 0.25% CaGP Gel (HP/NaF/CaGP) and 5) HP Blue 35% Gel (HP Blue). The bleaching gels were applied thrice, for 40 min, at intervals of 7 days each. After 21 days, the final surface hardness (SHf), integrated hardness (IH), Polydispersity Index (PdI) and Zeta Potential (Zp), surface roughness (Ra, after and before), and surface/structural analysis by Scanning Electron Microscopy (SEM) were determined. The data were submitted to ANOVA (one-way and two-way) followed by the Student-Newman-Keuls test (α=0.05). RESULTS: The addition of NaF to HP reduced demineralization by 11.5% in relation to HP (p<0.05). The NaF/CaGP association reduction is 22.8 and 20% higher in comparison to HP/NaF/CaGP and HP Blue, respectively. The IH when the PH/NaF/CaGP bleaching gel was applied, was 14% higher compared to HP and HP Blue groups. CONCLUSIONS: It can be concluded that the association of NaF and CaGP with the 35% hydrogen peroxide gel (HP/NaF/CaGP) significantly changed tooth enamel demineralization in terms of surface, depth, roughness, and enamel morphology.

Fluoride-induced hypertension by regulating RhoA/ROCK pathway and phenotypic transformation of vascular smooth muscle cells: In vitro and in vivo evidence.

Fluoride exposure has been implicated as a potential risk factor for hypertension, but the underlying mechanisms remain unclear. This study investigated the role of the RhoA/ROCK signaling pathway in fluoride-induced hypertension. Male Wistar rats were divided into different groups and exposed to varying concentrations of sodium fluoride (NaF) or sodium chloride (NaCl) via drinking water. The rats' blood pressure was measured, and their aortic tissue was utilized for high-throughput sequencing analysis. Additionally, rat and A7r5 cell models were established using NaF and/or Fasudil. The study evaluated the effects of fluoride exposure on blood pressure, pathological changes in the aorta, as well as the protein/mRNA expression levels of phenotypic transformation indicators (a-SMA, calp, OPN) in vascular smooth muscle cells (VSMCs), along with the RhoA/ROCK signaling pathway (RhoA, ROCK1, ROCK2, MLC/p-MLC). The results demonstrated that fluoride exposure in rats led to increased blood pressure. High-throughput sequencing analysis revealed differential gene expression associated with vascular smooth muscle contraction, with the RhoA/ROCK signaling pathway emerging as a key regulator. Pathological changes in the rat aorta, such as elastic membrane rupture and collagen fiber deposition, were observed following NaF exposure. However, fasudil, a ROCK inhibitor, mitigated these pathological changes. Both in vitro and in vivo models confirmed the activation of the RhoA/ROCK signaling pathway and the phenotypic transformation of VSMCs from a contractile to a synthetic state upon fluoride exposure. Fasudil effectively inhibited the activities of ROCK1 and ROCK2 and attenuated the phenotypic transformation of VSMCs. In conclusion, fluoride has the potential to induce hypertension through the activation of the RhoA/ROCK signaling pathway and phenotypic changes in vascular smooth muscle cells. These results provide new insights into the mechanism of fluoride-induced hypertension.

In-depth transcriptome and physiological function analysis reveals the toxicology of sodium fluoride in the fall webworm Hyphantria cunea.

Fluoride is an environmental pollutant that severely injures various organisms in ecosystems. Herein, the non-target organism, fall webworm (Hyphantria cunea), was used to determine the toxicological mechanism of NaF exposure. In this study, H. cunea exposed to NaF showed significant declines in growth and reproduction. The authors conducted RNA sequencing on adipose bodies and midgut tissues from NaF-exposed H. cunea larvae to uncover the toxicological mechanisms. The results showed that extracellular matrix-receptor interaction, pentose and glucuronate interconversions, fatty acid biosynthesis, and ferroptosis might contribute to NaF stress. NaF significantly decreased the antioxidant level, nitrous oxide synthase activity, and NO content, while significantly increasing lipid peroxidation. NaF induced significant changes in the expression of energy metabolism genes. However, the triglyceride content was significantly decreased and the lipase enzyme activity was significantly increased. Moreover, the expression levels of light and heavy chains of ferritin were inhibited in NaF-exposed H. cunea. NaF caused ferritin Fe2+overload in FerHCH1 and FerLCH knockdown H. cunea larvae, activated reactive oxygen species, and reduced the total iron content, eventually increasing the mortality H. cunea larvae. This study identified the toxicological mechanisms of NaF in lipid synthesis and energy metabolism in H. cunea, providing a basis for understanding the molecular mechanisms of NaF toxicity and developing pollution control strategies.

Use of NaF and FDG PET/CT Scan for the Assessment of Charcot Joint in Charcot-Marie-Tooth Disease: All That Glitters is Gold?

Increasingly Charcot neuroarthropathy (CN) is being recognized in patients with Charcot-Marie-Tooth (CMT) disease. In this report, we describe a case of CN in a CMT patient, adding to the very scarce literature describing this association. We additionally report his unique evaluation with fluorodeoxyglucose (FDG) and sodium fluoride (NaF) positron emission tomography/computed tomography (PET/CT) scanning, the study of which is limited in CN despite its promising role. A 54-year-old known case of CMT, presented with left foot pain, and swelling for 4 months. Weakness and sensory deficits as a result of CMT were evident in both lower and upper limbs. His x-ray was suggestive of CN. Both FDG and NaF PET/CT scanning demonstrated increased tracer uptake in the first tarsometatarsal joint (TMTJ), in keeping with CN. Recognition of the association of CMT with CN is of vital importance as early diagnosis relies on high clinical suspicion. Characterizing risk factors of CN in CMT patients is still under study. Moreover, there is lack of data evaluating the role of PET/CT in CN and specifically in the context of CMT.

In vitro effect of TiF4/NaF solution on the development of radiation-induced dentin caries.

OBJECTIVE: To evaluate the protective effect of an experimental solution containing TiF4/NaF on the development of radiation-induced dentin caries lesions. METHODOLOGY: bovine root samples were irradiated (70Gy) and distributed as following (n=12/group): Commercial Saliva (BioXtra), NaF (500 ppm F-), TiF4 (500 ppm F), TiF4/NaF (TiF4: 300 ppm F-, NaF: 190 ppm F-), and Phosphate buffer solution (PBS, negative control). Biofilm was produced using biofilm from irradiated patients and McBain saliva (0.2% of sucrose, at 37oC and 5% CO2) for five days. The treatments were applied 1x/day. Colony-forming units (CFU) were counted and demineralization was quantified by transversal microradiography. The ANOVA/Tukey test was applied for all parameters. RESULTS: All treatments reduced CFU for total microorganisms. TiF4 reduced Lactobacillus sp. (7.04±0.26 log10 CFU/mL) and mutans streptococci (7.18±0.28) CFU the most, when compared to PBS (7.58±0.21 and 7.75±0.17) and followed by NaF (7.12±0.31 and 7.34±0.22) and TiF4/NaF (7.16±0.35 and 7.29± 0.29). TiF4 and Commercial saliva showed the lowest integrated mineral loss (ΔZ-vol%.mm) (1977±150 and 2062±243, respectively) when compared to PBS (4540±335), followed by NaF (2403±235) and TiF4/NaF (2340±200). Commercial saliva was the only to significantly reduce mineral loss (LD-µm) (111±25) compared to PBS (153±24).Mean mineral loss (R-vol%) decreased by 35.2% for TiF4 (18.2±3.3) when compared to PBS (28.1±2.9) Conclusion: TiF4/NaF has a comparable anti-cariogenic effect to TiF4 and Commercial saliva under the model in this study.

Expression of SDF-1/CXCR4 and related inflammatory factors in sodium fluoride-treated hepatocytes.

At present, the mechanism of fluorosis-induced damage to the hepatic system is unclear. Studies have shown that excess fluoride causes some degree of damage to the liver, including inflammation. The SDF-1/CXCR4 signaling axis has been reported to have an impact on the regulation of inflammation in human cells. In this study, we investigated the role of the SDF-1/CXCR4 signaling axis and related inflammatory factors in fluorosis through in vitro experiments on human hepatic astrocytes (LX-2) cultured with sodium fluoride. CCK-8 assays showed that the median lethal dose at 24 h was 2 mmol/l NaF, and these conditions were used for subsequent enzyme-linked immunosorbent assays (ELISAs) and quantitative real-time polymerase chain reaction (qPCR) analysis. The protein expression levels of SDF-1/CXCR4 and the related inflammatory factors nuclear factor-κB (NF-κB), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and interleukin 1ß (IL-1ß) were detected by ELISAs from the experimental and control groups. The mRNA expression levels of these inflammatory indicators were also determined by qPCR in both groups. Moreover, the expression levels of these factors were significantly higher in the experimental group than in the control group at both the protein and mRNA levels (P < 0.05). Excess fluorine may stimulate the SDF-1/CXCR4 signaling axis, activating the inflammatory NF-κB signaling pathway and increasing the expression levels of the related inflammatory factors IL-6, TNF-α and IL-1ß. Identification of this mechanism is important for elucidating the pathogenesis of fluorosis-induced liver injury.

Hyperostosis frontalis interna on fluorine-18 sodium fluoride PET/computed tomography of obese cancer patients: a potential mimicker of metastasis.

OBJECTIVE: The objective of this retrospective study was to identify the uptake patterns and suggest a quantitative method to detect hyperostosis frontalis interna (HFI) on fluorine-18 sodium fluoride ([ 18 F]NaF) PET/computed tomography (CT). METHODS: Between January 2019 and December 2021, patients who underwent [ 18 F]NaF PET/CT with a BMI of 30 and above, were included. Three nuclear medicine consultants reviewed the studies to determine the presence and identify the uptake patterns of HFI. Quantitative evaluation was performed on PET images using the total number of counts over the frontal bone and the ratio of counts between the frontal bone and iliac crest. RESULTS: A total of 105 out of 249 cases were included in this study. Among these scans, there were 67 positive HFI in [ 18 F]NaF PET scans representing 64% of the studied population. As for the [ 18 F]NaF PET uptake pattern, there were 53 with uniformly diffused and 14 with heterogeneous uptake pattern. There were 17 out of 67 with positive HFI in [ 18 F]NaF PET scans but negative CT scans. CONCLUSION: HFI is a common finding on [ 18 F]NaF PET in obese patients and is probably underdiagnosed. HFI may present with a heterogeneous and diffuse pattern of uptake on [ 18 F]NaF PET. The proposed quantitative analysis using the count ratios is in agreement with the visual evaluation of [ 18 F]NaF PET images regardless of the CT findings. Awareness of this condition and its scintigraphic patterns is warranted since it can have clinical significance and may mimic other pathologies including metastasis in cancer patients.

Randomized clinical trial to compare three fluoride varnishes in preventing early childhood caries.

OBJECTIVES: To compare the effectiveness of two 5% sodium fluoride (NaF) varnishes containing casein phosphopeptide amorphous calcium phosphate (CPP-ACP) (MI VarnishTM) or tricalcium phosphate (TCP) (ClinproTM White) to the conventional 5% NaF varnish (Duraphat®) in preventing early childhood caries (ECC) in high-risk preschool children. METHODS: A double-blinded, randomized controlled trial recruited healthy 3-4-year-old children (N = 582) having at least one carious lesion (pre-cavitated or cavitated) after obtaining written informed consent from parents. Using a computer-generated random-number table, children were assigned to one of the 3 groups: Control group (n = 196): 5% NaF varnish (Duraphat®) or two test groups: 5% NaF with TCP (Clinpro™ White) (n = 193) and 5% NaF varnish with CPP-ACP (MI Varnish™) (n = 193) to receive quarterly (every 3 months) application over 24 months. RESULTS: Incidence of new caries over 2 years was 59.2% in MI Varnish™ group (n = 125), 65.1% in the Clinpro™ White group (n = 129) and 66.1% in the Duraphat® group (n = 127) (p = 0.466). The mean cavitated lesions increment was not significant among the 3 groups (p = 0.714), as was the mean increment in non-cavitated carious lesions (p = 0.223). There was no significant difference (p = 0.630) in the distribution of total fluoride varnish applications among the three groups. Also, no significant difference was found in comparison of outcomes among the different number of fluoride varnish applications received by children in each group. CONCLUSIONS: Both calcium- and phosphate-containing NaF varnishes showed similar efficacy against cavitated and non-cavitated carious lesions as compared to conventional NaF varnish in high-risk preschool children. CLINICAL SIGNIFICANCE: Randomized trial provided a crucial opportunity to advance the understanding of the clinical effectiveness of different fluoride varnishes in preventing early childhood caries. Varnishes containing tricalcium phosphate or casein phosphopeptide amorphous calcium phosphate when compared to sodium fluoride varnish, demonstrated a similar efficacy against early childhood caries in high caries-risk preschool children.

Brain homogenate stability for stimulant drugs.

Brain can be a useful specimen for toxicology testing as it is a protected and isolated organ with lower metabolic activity than other tissues, but there is currently no published data supporting the stability of stimulant drugs in prepared brain homogenates. Brain homogenates were evaluated to determine the stability of the following stimulant drugs: amphetamine, benzoylecgonine, bupropion, cocaethylene, cocaine, ephedrine, methylenedioxyamphetamine, methylenedioxymethamphetamine, methamphetamine, and phentermine. Four different homogenates were prepared at a 1:4 dilution with deionized water and fortified at 500 ng/mL of: cocaine without sodium fluoride, cocaine with 1% sodium fluoride, stimulant drugs other than cocaine without sodium fluoride, and stimulant drugs other than cocaine with 1% sodium fluoride. The fortified homogenates were aliquoted into 13 × 100-mm screw cap tubes and stored at room temperature (∼20°C), refrigerated (2-8°C), or frozen (<-5°C) and analyzed in triplicate on Days 0, 1, 3, 7, 14, 30, 60, and 90. Analytes were considered stable as long as the difference in analyte/internal standard response ratio from Day 0 was less than 20% and the peaks met qualitative acceptance criteria. All analytes were stable for up to 90 days when stored frozen with or without sodium fluoride and had variable stability at all other evaluated conditions.

Protecting primary teeth from dental erosion through bioactive glass.

OBJECTIVES: The present study aimed to evaluate the effectiveness of bioactive glass (BAG) in preventing dental erosion in primary teeth. METHODS: Enamel and dentin specimens (2 × 2 × 2 mm) were obtained from extracted primary teeth, which were randomly divided into the following groups based on the pretreatments (n = 12): DW (deionized water), NaF (2 % sodium fluoride), 2BAG (2 % BAG), 4BAG (4 % BAG), 6BAG (6 % BAG), and 8BAG (8 % BAG). The specimens were immersed in the respective solutions for 2 min and subjected to in vitro erosive challenges (4 × 5 min/d) for 5 d. The erosive enamel loss (EEL), erosive dentin loss (EDL), and the thickness of the demineralized organic matrix (DOM) were measured using a contact profilometer. The surface microhardness (SMH) was measured, and the percentage of SMH loss (%SMHL) was calculated. The surface morphology and mineral composition were evaluated by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. RESULTS: After the erosive challenges, the EEL, EDL, and%SMHL of the 2BAG, 4BAG, 6BAG, and 8BAG groups significantly reduced, with the greatest reduction was observed in the 6BAG (EEL: 6.5 ± 0.2 µm;%SMHL in enamel: 12.8 ± 2.6; EDL: 7.9 ± 0.3 µm; %SMHL in dentin: 22.1 ± 2.7) and 8BAG groups (EEL: 6.4 ± 0.4 µm;%SMHL in enamel: 11.0 ± 1.9; EDL: 7.8 ± 0.5 µm; %SMHL in dentin: 22.0 ± 2.5) (P < 0.05). With increasing BAG concentrations, the number of surface deposits containing Ca, P, and Si increased. CONCLUSIONS: 6BAG was the most effective for preventing dental erosion in primary teeth and showed a particularly strong potential for dentin erosion prevention. CLINICAL SIGNIFICANCE: Bioactive glass, especially at a 6 % concentration, has proven effective in reducing erosive tooth wear and surface microhardness loss while also protecting demineralized organic matrix in primary dentin.

Effects of NaF versus SDF treatment on microhardness of artificial radiation caries at cervical and root areas.

This study aimed to compare the effect of silver diamine fluoride (SDF) and fluoride varnish (NaF) on the Vickers microhardness (VHN) of enamel and dentin after radiotherapy and pH-cycling. Human premolars were cut longitudinally, embedded and serially polished. The VHN of enamel/dentin and irradiated enamel/dentin were evaluated. The irradiated specimens were treated with either NaF or SDF, subjected to pH-cycling then VHN test for 4 days. Consequently, they were subjected to energy-dispersive X-ray (EDX) analysis. Radiation adversely affect enamel VHN (p<0.05), whereas dentin VHN was not affected (p>0.05). After pH-cycling, a significant decrease in dentin VHN was observed on day 2 for all groups, whereas enamel VHN was significantly decreased in the control group on day 4. SDF-treated enamel demonstrated higher VHN than that of NaF on day 3. Caries prevention effect of SDF and NaF were observed on enamel, where SDF was proved to be superior to NaF.

Immediate and sustained root caries prevention of fluoride varnish combined with toothpastes: findings of clinical relevance?

DESIGN: An in vitro study to determine the immediate and sustained effect of fluoride varnish and its combination with fluoride toothpastes in preventing the development of root caries. CASE SELECTION: Human root dentine samples (150) were randomly divided into five experimental protocols of 30 specimens each: 1) fluoride varnish (22,600 ppm fluoride and 1-5% CPP-ACP); 2) fluoride varnish followed by Paste One (1100 ppm sodium fluoride and CPP-ACP); 3) fluoride varnish followed by Paste Plus (900 ppm sodium fluoride and CPP-ACP); 4) fluoride varnish followed by Paste One and Paste Plus; and 5) no treatment (control). A layer of varnish was applied to specimens except the control group and was left in situ for 18 h. The varnish layer was removed, and the various toothpaste treatments were initiated. Half of the specimens in each group were assigned to a short-term incubation model in which they were immediately subjected to a 7-day cariogenic challenge consisting of a combination of human saliva and artificial saliva containing 2% sucrose. The other half of the specimens in each group were assigned to the long-term incubation model in which the experimental protocol was continued for 8 weeks before initiating the seven-day cariogenic challenge. The protocols were evaluated by assessing dentine porosity (rhodamine intensity), mineral density, biofilm biomass, and viability assays. DATA ANALYSIS: Confocal laser scanning microscopy was used to determine dentine porosity and Levene's test was used to verify the assumption of equality of variances and normal distribution of errors before two-way ANOVA and the Games-Howell test were carried out at a significance level of 0.05 for both incubation models. Microcomputed tomography was used to determine mineral density with statistical analysis involving Levene's test, two-way ANOVA and Tukey's test at a significance level of 0.05 for both incubation models. Biomass was evaluated using a biofilm biomass assay with analysis of optical density data using Levene's test, ANOVA and Scheffe's test at a significance level of 0.05. RESULTS: For both the short- and long-term incubation models, all the experimental regimes resulted in a statistically significant decrease in dentine porosity and an increase in mineral density when compared to the control group. Fluoride varnish followed by both pastes and fluoride varnish followed by Paste One resulted in a statistically significant decrease in dentine porosity for some depths in both models when compared to fluoride varnish alone. Changes in dentine porosity and mineral density were observed within groups over time. All the experimental regimes demonstrated anti-biofilm effects. Immediate and sustained anti-caries effects were observed for all preventive protocols, with the combination of fluoride varnish and Paste One resulting in superior additional anti-caries effects. CONCLUSIONS: The authors concluded that all protocols demonstrated immediate and sustained anti-caries effects against the development of root caries despite variations in effects over time. The combination of fluoride varnish and Paste One resulted in additional anti-caries effects that were consistently superior, with no additional effects being observed when Paste Plus was added in combination. The authors suggest that, within the study's limitations, topical fluoride varnish seems to have a protective effect on root surfaces for up to eight weeks and that fluoride varnish should be considered as an important adjunct strategy in the prevention of root caries in older adults.

Clinical effect of chlorhexidine and sodium fluoride on corrosion behavior and surface topography of nitinol orthodontic archwires.

BACKGROUND: Alterations in the mechanical properties of the materials utilized in orthodontic appliances could affect the working properties of the appliances, thereby affecting clinical progress and outcome. Numerous studies have confirmed the correlation between alloy corrosion and raised surface roughness, which has a direct impact on the working characteristics of orthodontic archwires. METHODS: Thirty nickel-titanium (NiTi) orthodontic archwires were utilized in this study. Patients were randomly selected and allocated into three groups according to the randomization plan; (The control group): subjects practiced regular oral hygiene; (The fluoride group): subjects used fluoride for intensive prophylaxis; (The chlorhexidine group): subjects used chlorhexidine. Representative samples were evaluated by SEM, and then SEM images with high resolution were examined using Image J software to determine the surface roughness and obtain the results for further statistical analysis. RESULTS: Our findings indicated a significant difference was found between the three groups regarding the anterior and posterior parts between the control and the two other groups and a non-significant difference between NaF and CHX groups. Overall, the p-value for group comparisons was 0.000 for both parts, indicating a highly significant difference especially between the control and NaF groups. CONCLUSION: Mouthwashes containing sodium fluoride demonstrated more significant surface alterations than the control and CHX groups and should be prescribed in accordance with orthodontic materials to reduce side effects.