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

Objective: To analyze correlation of occupational hydrogen fluoride exposure to low doses of bone metabolism index through occupational epidemiological investigation and benchmark dose calculation. Methods: In May 2021, using cluster sampling method, 237 workers exposed to hydrogen fluoride in a company were selected as the contact group, and 83 workers not exposed to hydrogen fluoride in an electronics production company were selected as the control group. The external exposure dose and urinary fluoride concentration, blood and urine biochemical indicators of the workers was measured.The relationship between external dose and internal dose of hydrogen fluoride was analyzed. The external dose, urinary fluoride was used as exposure biomarkers, while serum osteocalcin (BGP), serum alkaline phosphatase (AKP) and urinary hydroxyproline (HYP) were used as effect biomarkers for bone metabolism of hydrogen fluoride exposure. The benchmark dose calculation software (BMDS1.3.2) was used to calculate benchmark dose (BMD) . Results: Urine fluoride concentration in the contact group was correlated with creatinine-adjusted urine fluoride concentration (r=0.69, P=0.001). There was no significant correlation between the external dose of hydrogen fluoride and urine fluoride in the contact group (r=0.03, P=0.132). The concentrations of urine fluoride in the contact group and the control group were (0.81±0.61) and (0.45±0.14) mg/L, respectively, and the difference between the two groups was statistically significant (t=5.01, P=0.025). Using BGP, AKP and HYP as effect indexes, the urinary BMDL-05 values were 1.28, 1.47 and 1.08 mg/L, respectively. Conclusion: Urinary fluoride can sensitively reflect the changes in the effect indexes of biochemical indexes of bone metabolism. BGP and HYP can be used as early sensitive effect indexes of occupational hydrogen fluoride exposure.
Humans ; Fluorides/adverse effects* ; Hydrofluoric Acid ; Benchmarking ; Biomarkers ; Occupational Exposure/adverse effects*

Objective: Using CFD technology to grasp the distribution and diffusion of hydrogen fluoride in an electrolytic fluorine plant, provide guidance and scientific basis for enterprises to carry out occupational health management in enterprises, install hazardous substance alarm devices, and protect workers' occupational health. Methods: In July 2019, the diffusion law of hydrogen fluoride gas produced in an electrolytic fluorine plant is selected as the research object. Through the establishment of models and grids, the Fluent numerical simulation method is finally used to simulate the diffusion and distribution of hydrogen fluoride gas under ventilation conditions. Results: The results showed that the average concentration of hydrogen fluoride was 0.045 mg/m(3) in the workplace, and the absorbed zone height (1.5 m) was 0.02 mg/m(3) in the inspection channel, which was in accordance with the national standard. However, there is eddy current above the electrolyzer near the inlet, may lead to the accumulation of hydrogen fluoride gas. Conclusion: The research of CFD numerical simulation method on the distribution and diffusion of hydrogen fluoride concentration in electrolytic fluorine plant can be applied to the prevention, control and management of occupational hazards in electrolytic fluorine plant.
Computer Simulation ; Fluorides ; Humans ; Hydrofluoric Acid ; Occupational Exposure/prevention & control* ; Occupational Health

The aim of this study was to compare fluoride release and surface changes according to different orthodontic bracket adhesives the application of fluoride products. We used non-fluoridated composite resin Transbond fluoridated composite resins Blugloo and LightBond, resin-modified glass ionomer Rely XTM Luting 2, and conventional glass ionomer Fuji I®. Fluoride release of five orthodontic bracket adhesives and fluoride release ability after application of three fluoride products (1.23% acidulated phosphate fluoride gel, Tooth Mousse Plus®, Fluor Protector, and a toothbrush with sodium fluoride-containing toothpaste) were measured using a fluoride electrode that was connected to an ion analyzer. After 4 weeks of fluoride application, the surface roughness and surface morphology were examined using a surface roughness tester and field emission scanning electron microscopy. The amounts of fluoride release were observed not only on application of Tooth Mousse Plus® and Fluor Protector on resin-modified glass ionomer Rely XTM Luting 2 and Fuji I®, but also during tooth brushing using fluoride-containing toothpaste. After application of Tooth Mousse Plus®, except Transbond XT, the surface roughness increased, and all orthodontic adhesives showed a partial drop of micro-particle filler. On application of 1.23% acidulated phosphate fluoride gel on all orthodontic bracket adhesives, their surface roughness increased. To bond the orthodontic bracket, resin-modified glass ionomer Rely XTM Luting 2 and Fuji I® adhesives are highly recommended if the amount of fluoride release is considered to confer a preventative effect on dental caries, and among the fluoride products, Tooth Mousse Plus® and Fluor Protector are better than 1.23% acidulated phosphate fluoride gel, and these are expected to prevent dental caries even during tooth brushing with fluoride-containing toothpaste.
Acidulated Phosphate Fluoride ; Adhesives* ; Composite Resins ; Dental Caries ; Dental Cements ; Electrodes ; Fluorides* ; Glass ; Microscopy, Electron, Scanning ; Orthodontic Brackets* ; Sodium ; Surface Properties* ; Tooth ; Toothpastes

Hydrofluoric acid is one of the strongest irritating, corrosive and poisonous inorganic chemicals. The most significant chronic consequence of excessive fluoride exposure is the disorder of skeletal system and connective tissue. The first stage of osteofluorosis consists of an increase in the density of flatbone such as pelvic bone and vertebral bones, with coarseness and blurring of bone trabecular. Therefore we wanted to observe the change of the bone density among workers exposed to hydrofluoric acid. Questionnaires and radiological investigations were performed for 39 hydrofluoric acid manufacturing factory worker sexposed to hydrofluoric acid. And then authors checked urinary fluoride level by fluoride ion method. the radiographs were doubly read by two radiologists for reliability. The results were as follows; 1. There was a significant difference in urinary fluoride level (p<0.01), but not in age, in tenure(p>0.05) among workers by the job title. 2. By the two radiologists, eight cases were read as bone fluorosis. The prevalence rate of bone fluorosis was 20.5%. 3. There was not a significant difference in general characteristic such as age, tenure and in muculoskeletal signs and symptoms between the fluorosis group and the normal group. 4. However, a close relationship between the occurence of the change of bone density and the degree of fluorde exposure such as burn was found. The difficulties in diagnosing fluorosis result from the questionable sensitively of x-ray techniques and from the non-specific associated signs and symptoms. A quantitative method such as densitometry to assessosteosclerosis and bone structure alteration and a follow-up study are needed.
Bone Density* ; Burns ; Connective Tissue ; Densitometry ; Fluorides ; Follow-Up Studies ; Hydrofluoric Acid* ; Inorganic Chemicals ; Pelvic Bones ; Prevalence ; Questionnaires

Hydrofluoric acid is one of the strongest irritating, corrosive and poisonous inorganic chemicals. Hydrofluoric acid burns are occurring with ever-increasing frequency due to the wide use of this acid in industries. Hydrofluoric acid burns are characterized by severe progressive tissue destruction and excruciating pain due to the unique properties of the freely dissolvable fluoride ion. The authors reviewed medical records of 32 cases(36 spells) of hydrofluoric acid burns which occurred in a hydrofluoric acid manufacturing factory from Sep. 1, 1990 to June 30, 1993. The results are as follows; 1. Eleven measurements of air concentrations of hydrofluoric acid by detection tube method from 1990 to 1992 were all below TLV(Department of Labor, R. O. K). 2. There were 19 cases(22 spells) of hydrofluoric acid burns which occurred during the study period among regular employees. The overall incidence density of hydrofluoric acid was 17.8 cases(20.6 spells) per 100 person-year. Incidence density was 19.0 cases(22.0 spells) per 100 person-year among male workers and there were no female cases. Incidence density was 32.9 cases(38.3 spells) per 100 person-year among production workers and 1.9 cases(1.9 spells) per 100 person-years among management workers with the difference being statistically significant(P<0.01). 3. Of 32 cases(36 spells) of hydrofluoric acid burns among workers who were regularly employed or temporarily employed, 26 spells(81.2%) were between age 20 to 39. In 15 spells(41.7%) burns occurred between 12 : 00 and 17 : 59 with 16 spells(44.3%) having arrived at hospital within 2 hours after the accident. 4. Of 36 spells, the main cause of hydrofluoric acid burns were by splashes(8 spells, 22.2 %). The most frequent site of burns were fingers and pain was the most frequent symptom. Thirty spells(83.3%) of the hydrofluoric acid burns were treated with local injection of antidote(calcium gluconate). Complete recovery without scarring were observed in most of the cases(34 out of 36 cases, 94.4%). The study results suggest that to prevent hydrofluoric acid burns, environmental control and the wearing of hydrofluoric acid resistant protective clothes and gloves are important. It is also stressed that establishment of an emergency management and a transfer system for hydrofluoric acid burn victims is necessary.
Burns* ; Burns, Chemical ; Cicatrix ; Emergencies ; Female ; Fingers ; Fluorides ; Humans ; Hydrofluoric Acid* ; Incidence ; Inorganic Chemicals ; Male ; Medical Records

PURPOSE: To evaluate the adhesion to CAD/CAM feldspathic blocks by failure analysis and shear bond strength test (SBSt) of different restorative systems and different surface treatments, for purpose of moderate chipping repair. MATERIALS AND METHODS: A self-adhering flowable composite (Vertise Flow, Kerr) containing bi-functional phosphate monomers and a conventional flowable resin composite (Premise Flow, Kerr) applied with and without adhesive system (Optibond Solo Plus, Kerr) were combined with three different surface treatments (Hydrofluoric Acid Etching, Sandblasting, combination of both) for repairing feldspathic ceramics. Two commercial systems for ceramic repairing were tested as controls (Porcelain Repair Kit, Ultradent, and CoJet System, 3M). SBSt was performed and failure mode was evaluated using a digital microscope. A One-Way ANOVA (Tukey test for post hoc) was applied to the SBSt data and the Fisher's Exact Test was applied to the failure analysis data. RESULTS: The use of resin systems containing bi-functional phosphate monomers combined with hydrofluoric acid etching of the ceramic surface gave the highest values in terms of bond strength and of more favorable failure modalities. CONCLUSION: The simplified repairing method based on self-adhering flowable resin combined with the use of hydrofluoric acid etching showed high bond strength values and a favorable failure mode. Repairing of ceramic chipping with a self-adhering flowable resin associated with hydrofluoric acid etching showed high bond strength with a less time consuming and technique-sensitive procedure compared to standard procedure.
Adhesives ; Ceramics* ; Hydrofluoric Acid ; Methods*

PURPOSE: The aim of this study was to evaluate whether fluorides at various pH cause changes in the surface roughness of titanium implants that alter the adherence of bacterial biofilms. MATERIALS AND METHODS: The titanium disks were assigned randomly to the following seven groups according to the fluoride agents and application time (1 minute or 30 minute) used: control (no treatment); group 1 (1.23% acidulated phosphate fluoride [APF] at pH 3.5 for 1 minute); group 2 (1.23% APF at pH 3.5 for 30 minute); group 3 (1.23% APF at pH 4.0 for 1 minute); group 4 (1.23% APF at pH 4.0 for 30 minute); group 5 (2% NaF gel at pH 7.0 for 1 minute); group 6 (2% NaF gel at pH 7.0 for 30 minute). The surface roughness of the titanium disks and the amount of adherent bacteria were measured. RESULTS: Group 2 showed a significantly greater surface roughness than the control group (P < 0.0001). No significant differences in the amount of surface bacteria were observed between the treated samples and the controls. In addition, there were no significant differences in bacterial adherence relative to the incubation period between the treated samples and the controls. CONCLUSION: The surface roughness of the titanium disks was significantly greater after treatment with APF at pH 3.5 for 30 min compared with that of the controls. In addition, we found that the amount of Porphyromonas gingivalis, Fusobacterium nucleatum, and Aggregatibactor actinomycetemcomitans was similar among all groups.
Acidulated Phosphate Fluoride ; Bacteria ; Bacterial Adhesion ; Biofilms ; Fluorides ; Fusobacterium nucleatum ; Hydrogen-Ion Concentration ; Porphyromonas gingivalis ; Titanium*

OBJECTIVETo evaluate the efficacy of Tooth Mousse in reducing enamel demineralization lesions adjacent to bonded orthodontic brackets and promoting remineralization in vitro.

METHODS60 bovine teeth with bonded orthodontic brackets were randomly divided into three groups, negative control group, positive control group and experimental group, applied separately with distilled water, Duraphat fluoride varnish, Tooth Mousse. 3 groups were dipped into an artificial caries solution and an artificial saliva solution, cycling between them. All samples were detected by polarized light microscope, scanning electron microscope and electron probe micro-analysis.

RESULTSPolarized light microscope showed that the enamel surface of the experimental group were completed, the areas of positive birefringence were decreased obviously. Scanning electron microscope showed that a large number of deposits were found on the dental enamel surface of the experimental group, filled in the small local concave of enamel surface. Compared with the control group, electron probe micro-analysis showed that calcium and phosphate concentration of enamel surface was higher in experimental group than in negative control group (P<0.05), there was no significant differences between experimental group and positive control group (P>0.05).

CONCLUSIONTooth Mousse can reduce enamel demineralization and promoting remineralization in vitro.

Animals ; Cariostatic Agents ; Caseins ; Cattle ; Dental Caries ; Dental Enamel ; Fluorides ; Fluorides, Topical ; Orthodontic Brackets ; Phosphates ; Sodium Fluoride ; Tooth Demineralization

OBJECTIVETo evaluate the clinical effect of fluoride varnish in preventing caries of primary teeth, and to compare the caries prevention effects of fluoride varnish with two different concentrations.

METHODS150 children whose ages were three year-old were randomly chosen from one of nurseries of Chongqing, and were randomly divided into four groups with 37 children in 0.5% fluoride varnish group, 38 children in 0.1% fluoride varnish group, 39 children in 0.5% sodium fluoride group and 36 children in blank group. The groups included 71 'girls and 79 boys. Protective measure was applied every half an year and the research has lasted for two years. The research was designed by double-blinded methods, and was carried out with the dental caries standard suggested by World Health Organization. All the data were collected and the clinical effects of four groups were compared.

RESULTSThe average caries index and caries surface index of 0.1% fluoride varnish group and those of control groups were significantly higher than that of 0.5% fluoride varnish group. There were no significant difference between the average caries index and caries surface index of 0.1% fluoride varnish group and those of control groups.

CONCLUSION0.5% fluoride varnish was effective in preventing caries of primary teeth.

Cariostatic Agents ; Child ; Dental Caries ; Female ; Fluorides ; Fluorides, Topical ; Humans ; Male ; Paint ; Phosphates ; Sodium Fluoride ; Tooth, Deciduous