OBJECTIVETo study the effect of excessive fluoride on calcium overload and apoptosis in cultured rat ameloblasts in vitro.

METHODSLogarithmic-phase ameloblasts (HAT-7) were treated with 0, 0.4, 0.8, 1.6, 3.2, and 6.4 mmol · L(-1) sodium fluoride (NaF) solution. Cell activities were detected by using a Cell Counting Kit 8 (CCK-8) assay after 48 h of treatment. The effect of fluoride on cell apoptosis was analyzed by using flow cytometry. Excessive fluoride-induced calcium concentration and calreticulin expression changes in ameloblasts were detected by using laser scanning confocal microscopy, Western blot analysis, and real-time quantitative polymerase chain reaction.

RESULTSNaF inhibited ameloblast activity at 1.6, 3.2, and 6.4 mmol · L(-1) (dose-dependent) after 48 h of induction. The Ca2+ fluorescence intensity of HAT-7 cells incubated with 1.6 and 3.2 mmol · L(-1) NaF was higher than that in the control group. The fluoride-induced early-stage apoptosis of ameloblasts after 48 h of induction and the early-stage apoptosis rate was positively correlated with fluoride concentration. Calreticulin mRNA expression in HAT-7 cells was higher than that in the control group after 48 h of incubation with 0.8, 1.2, and 1.6 mmol · L(-1) NaF.

CONCLUSIONExcessive fluoride-induced calcium overload in ameloblasts and further caused endoplasmic reticulum stress-mediated apoptosis.

Ameloblasts ; Animals ; Apoptosis ; Calcium ; Calcium Fluoride ; Fluorides ; Phosphates ; Rats ; Sodium Fluoride

OBJECTIVETo evaluate the reliability of a method of measuring the total fluoride in fluoride-containing toothpastes with acid diffusion and fluoride selective electrode.

METHODSFour brands of commercially available non-fluoride toothpastes and fluoride-containing toothpastes were sampled. Fluoride was extracted from the toothpastes in 2 mol/L HC10(4) at room temperature overnight and then subjected to the measurement with fluoride electrode.

RESULTSFluoride recovery of the non-fluoride toothpastes containing calcium as abrasive by this method was 99.5%-100.5%, more than 94% of total fluoride was measured from the marketed fluoride toothpastes, and the variation coefficient of this method was less than 1.54%. While the abrasive was silicon, the fluoride recovery of the non-fluoride toothpastes was 83.4%, and 89.7% of total fluoride was measured from the marketed fluoride-containing toothpastes.

CONCLUSIONThe amount of total fluoride in the calcium containing toothpaste can be detected simply and accurately measured by acid diffusion and fluoride selective electrode.

Calcium ; Electrodes ; Fluorides ; Phosphates ; Reproducibility of Results ; Sodium Fluoride ; Toothpastes

OBJECTIVE: To study and compare the effects of different demineralization-inhibition methods on the shear bond strength (SBS) and fracture mode of an adhesive used to bond orthodontic brackets to demineralized enamel surfaces. METHODS: Eighty freshly extracted, human maxillary premolars were divided into 4 equal groups and demineralized over the course of 21 days. Brackets were bonded to the demineralized enamel of teeth in Group 1. In Group 2, bonding was performed following resin infiltration (ICON(R), DMG, Hamburg, Germany). Before bonding, pre-treatment with acidulated phosphate fluoride (APF) or solutions containing casein phosphopeptide-amorphous calcium phosphate with 2% neutral sodium fluoride (CPP-ACP/wF) was performed in Groups 3 and 4, respectively. The SBS values of the brackets were measured and recorded following mechanical shearing of the bracket from the tooth surface. The adhesive remnant index (ARI) scores were determined after the brackets failed. Statistical comparisons were performed using one-way ANOVA, Tukey's post-tests, and G-tests. RESULTS: Significant differences were found in some of the intergroup comparisons of the SBS values (F = 39.287, p < 0.001). No significant differences were found between the values for the APF-gel and control groups, whereas significantly higher SBS values were recorded for the resin-infiltrated and CPP-ACP/wF-treated groups. The ARI scores were also significantly different among the 4 groups (p < 0.001). CONCLUSIONS: Tooth surfaces exposed to resin infiltration and CPP-ACP/wF application showed higher debonding forces than the untreated, demineralized surfaces.
Acidulated Phosphate Fluoride ; Adhesives ; Bicuspid ; Calcium ; Calcium Phosphates ; Caseins ; Dental Enamel ; Humans ; Oral Hygiene ; Orthodontic Brackets ; Sodium Fluoride ; Tooth

The purpose of this study was to observe the effects of sodium fluoride on the bony iepair and regeneration processes after the rapid palatal expansion in the growing dogs. Eighteen dogs were divided into experimental and control groups. They were in the late mixed dentition. The rapid palatal expansion was undertaken in all the animals(180 turn/day) for ten days. The animals were sacrificed on 0, 15 and 45 days; after the finish of expansion. One mg NaF/kg of body weight/day were given orally to the experimental group. Blood sampl, s were drawn before and after expansion and the serum calcium, phosphate and alkaline phosphatase level were measured. The undecalcified bone section of midpalatal suture area was made, and observed under the light microscopy. The results were as follows; 1. The day after expansion, the infiltration of inflammatory cells were prominent and the new bone formation started at the edges of the two palatal plates bodering the midpalatal suture in both groups. Especially, the newly formed osteoid were very extensive and the osteoblasts lining the osteoid were very active in the experimental group. 2. At fifteen days after expansion, the active osteoblasts lining the osteoid at the surface of trabecular bony spicules and active new bone formation were observed in the both groups. However, the cellular activity and new bone formation were more prominent in the experimental group. 3. At forty five days after expansion, the continuous osteoid and new bone formation and active osteoblasts were observed in the experimental group. But these phenomena were not observed in the control group. In the control group, the numerous osteoclasts were adjacent midpalatal suture and the bony remodeling process was begun. The serum alkaline phosphatase level was maintained highly in the experimental group, but decreased in the control. According to the above results, the author reached the conclusion that sodium fluoride has the stimulation effects on the osteoid production of the osteoblasts during the healing process after the rapid palatal expansion more continuously.
Alkaline Phosphatase ; Animals ; Calcium ; Dentition, Mixed ; Dogs* ; Microscopy ; Osteoblasts ; Osteoclasts ; Osteogenesis ; Regeneration ; Sodium Fluoride* ; Sodium* ; Sutures

In order to explore the mechanisms underlying the calcium alleviating fluorosis at protein level, we made an attempt to establish fluorosis and calcium supplementation rat models to isolate and identify bone differential proteins. The bone proteins of different groups were compared by two-dimensional electrophoresis (2-DE) and mass spectrometry (MALDI-TOF MS), and analyzed by gene ontology annotation, pathway enrichment and interaction networks. The 17 proteins were identified in the fluorosis group (F) and the fluorosis calcium supplement group (F+Ca), including type I collagen (Col1a1), actin (Actb), protein glutamine transferase 2 (Tgm2), compared with the control group (C). These differential proteins are enriched in 38 bone metabolic pathways such as focal adhesion, PI3K-Akt signaling pathway, and AMPK signaling pathway. And the functions of these proteins are mainly related to cytoskeleton, energy metabolism, substance transport, ion channel, and apoptosis. Therefore, it is speculated that calcium may alleviate the fluoride-induced bone damage by regulating the focal adhesion, PI3K-Akt, AMPK and other signaling pathway, but the specific mechanism needs further research.
Animals ; Calcium ; Dietary Supplements ; Fluoride Poisoning ; Fluorosis, Dental ; Phosphatidylinositol 3-Kinases ; Rats

It was hypothesized that NaF induces calcium sensitization in Ca2+-controlled solution in permeabilized rat mesenteric arteries. Rat mesenteric arteries were permeabilized with beta-escin and subjected to tension measurement. NaF potentiated the concentration-response curves to Ca2+ (decreased EC50 and increased E(max)). Cumulative addition of NaF (4.0, 8.0 and 16 mM) also increased vascular tension in Ca2+-controlled solution at pCa 7.0 or pCa 6.5, but not at pCa 8.0. NaF-induced vasocontraction and GTPgammaS-induced vasocontraction were not additive. NaF-induced vasocontraction at pCa 7.0 was inhibited by pretreatment with Rho kinase inhibitors H1152 or Y27632 but not with a MLCK inhibitor ML-7 or a PKC inhibitor Ro31-8220. NaF induces calcium sensitization in a Ca2+-dependent manner in beta-escin-permeabilized rat mesenteric arteries. These results suggest that NaF is an activator of the Rho kinase signaling pathway during vascular contraction.
Amides ; Animals ; Azepines ; Calcium ; Contracts ; Escin ; Indoles ; Mesenteric Arteries ; Naphthalenes ; Passive Cutaneous Anaphylaxis ; Pyridines ; Rats ; rho-Associated Kinases ; Sodium ; Sodium Fluoride

The purpose of this study was to evaluate the in-vitro efficacy of the active ingredients of dentifrice following treatment time. The whitening effect was evaluated by a change in lightness value relative to the contact time of hydrogen peroxide, by using artificially stained hydroxyapatite discs. The anti-calculus effect was assessed based on the amount of calcium eluted from the human dental calculus by sodium pyrophosphate. Remineralization was evaluated by the Vickers hardness test following the application of sodium fluoride to bovine enamel. In order to view dentinal tubules occlusion, the formation of insoluble calcium salts by bovine dentin specimens was observed using scanning electron microscopy. Change in lightness value (ΔL) was 5.50±1.51 after 1 min of treatment, 5.73±0.43 after 3 min, 8.64±0.24 after 10 min, 18.93±0.76 after 30 min, and 27.35±0.54 after 60 min. The amount of calcium eluted from the human dental calculus was 4.23±0.14 ppm after 1 min of treatment, 4.51±0.04 ppm after 3 min, 12.12±0.16 ppm after 10 min, 17.85±0.81 ppm after 30 min, and 25.15±0.32 ppm after 60 min. The Vickers hardness change value (ΔVHN) was 1.96±1.44 after 1 min, 1.52±1.06 after 3 min, 9.06±0.15 after 10 min, 10.83±5.13 after 30 min, and 12.55±2.09 after 60 min. Partial dentinal tubules occlusion was observed at 10 min and complete occlusion was evident at 60 min. In summary, the use of patch type dentifrices for 10, 30, or 60 min were 1.57 to 8.26 times more effective than using the paste type dentifrices for 1 to 3 min. Based on these findings, it is reasonable to expect that the use of patch type dentifrices for 10 min would lead to remineralization, anti-calculus and dentinal tubules occlusion effects, and that use for 30 min would result in a whitening effect.
Calcium ; Dental Calculus ; Dental Enamel ; Dentifrices* ; Dentin ; Durapatite ; Hardness ; Hardness Tests ; Humans ; Hydrogen Peroxide ; Microscopy, Electron, Scanning ; Salts ; Sodium ; Sodium Fluoride

OBJECTIVETo study expression of proto-oncogenes c-fos and its accompanying gene c-jun in osteoblasts activated by action of excessive fluoride in vivo and in vitro.

METHODSExperimental Wistar rats were exposed to sodium fluoride (NaF) added to their drinking water, and NaF was also added in cell culture supernatant for osteoblast-like cells in vitro. Expression of both mRNA and protein of c-fos and c-jun in bone-tissue of rats with chronic fluorosis and cultured osteoblast-like cells were determined by hybridization in situ, Western blot and immunohistochemistry at varied time periods after exposure.

RESULTSSodium fluoride could stimulate the proliferation of osteoblast in rats with chronic fluorosis and induce expression of both c-fos and c-jun in all envelops of the spine bone, as compared with its control group. Value of optical absorption in mRNA expression of c-fos and c-jun was 139.63 and 126.37, respectively, in rats with NaF plus high-calcium, significantly lower than that in control group with high-calcium only (107.74 and 117.48, respectively) (P < 0.001). Immunohistochemical analysis showed that protein level of c-fos and c-jun was significantly higher in rats with NaF plus high-calcium than that in control rats with high-calcium only, with values of optical absorption of 139.16, 131.15, 149.98 and 149.19 (P < 0.05), respectively, and protein level of c-fos and c-jun was significantly higher in rats with NaF plus low-calcium than that in control rats with low-calcium only, with values of optical absorption of 117.24, 111.46, 132.46 and 129.79 (P < 0.05), respectively. Western blotting showed that level of protein expression of c-fos and c-jun in periosteal osteoblasts was significantly higher in all rat groups with NaF than that in all control groups, with values of optical absorption of 123.32, 116.60, 115.97 and 108.30, respectively. mRNA expression of c-fos and c-jun in osteoblast-like cells treated with NaF for 12 h increased obviously, and remained at high level 48 h after exposure, with values of optical absorption of 114.80, 161.14, 118.20, and 150.41, respectively, as compared with that in control group (P < 0.001 and P < 0.05).

CONCLUSIONSExposure to excessive fluoride could stimulate activation and proliferation of both osteoblasts in rats and cultured osteoblast-like cells in vitro, and cause enhanced expression of mRNA and protein of both c-fos and c-jun. Over-expression of c-fos could play an important role in development and proliferation of skeletal lesions in rats with chronic fluorosis.

Animals ; Bone Diseases ; metabolism ; pathology ; Calcium ; pharmacology ; Cell Division ; drug effects ; Cells, Cultured ; Female ; Fluoride Poisoning ; metabolism ; pathology ; Gene Expression ; Male ; Osteoblasts ; cytology ; metabolism ; Proto-Oncogene Proteins c-fos ; biosynthesis ; genetics ; Proto-Oncogene Proteins c-jun ; biosynthesis ; genetics ; RNA, Messenger ; biosynthesis ; genetics ; Rats ; Rats, Wistar ; Sodium Fluoride ; pharmacology

Bone Density ; physiology ; Bone Diseases ; epidemiology ; etiology ; metabolism ; pathology ; Calcium ; metabolism ; China ; epidemiology ; Endemic Diseases ; Fluoride Poisoning ; epidemiology ; etiology ; metabolism ; pathology ; Humans ; Osteoblasts ; physiology ; Oxidative Stress ; Parathyroid Hormone ; metabolism ; Thioredoxins ; metabolism ; Transcription Factor AP-1 ; metabolism

OBJECTIVETo evaluate the anti-demineralization efficacy of Galla Chinesis in pH cycling model for elucidating the anti-root caries mechanism.

METHODAnti-demineralization efficacy evaluation of the natural medicine in the pH-cycling models was used . Sound human root blocks were pH-cycled through the treatment solution, acidic buffer and neutral buffer. The cycling times for demineralization study were 12 times, 2 times per day. The acidic buffers were retained for calcium analysis by atomic adsorption spectroscopy. The sections of blocks were analysed after pH-cycling by CLSM. Treatments were 4 g x L(-1). Galla Chinesis, 1 g x L(-1) NaF solution and distilled water.

RESULTGalla Chinesis was found to inhibit the demineralization in the pH cycling model. Although the effect was not as good as fluoride, there was no significant difference between the two groups.

CONCLUSIONThese data suggest that Galla Chinesis could modulate the mineralisation behaviour of root tissue in a defined chemical circumstance. These findings support the proposition that Galla Chinesis may be a promising anticaries natural medicine in the future.

Animals ; Calcium ; metabolism ; Cuspid ; drug effects ; pathology ; Dental Caries ; prevention & control ; Humans ; Hydrogen-Ion Concentration ; Insecta ; chemistry ; Materia Medica ; isolation & purification ; pharmacology ; Microscopy, Confocal ; Sodium Fluoride ; pharmacology ; Tooth Demineralization ; metabolism ; pathology ; prevention & control ; Tooth Remineralization ; Tooth Root ; drug effects ; metabolism ; pathology