Effect of Different Preparations of Fluoride Gel on Salivary pH of Albino Rats

Abstract Objective: To evaluate the effect of different preparations of fluoride gels on the salivary pH of albino rats. Material and Methods: This experimental study consisted of 40 Albino rats randomly divided into four equal groups. Group A was the control group and received no intervention. Experimental group B received a topical application of 0.2% sodium fluoride gel. Experimental group C received topical application of stannous fluoride gel 0.4%. Experimental group D received topical application of APF gel (1.23% acidulated phosphate fluoride gel). The different preparations of the gels were applied once daily for 4 minutes on the occlusal surface of the right maxillary molars for 14 days. Salivary pH values were recorded immediately after the application of gels with the help of pH paper on day 1 and day 14. Results: There was a significant difference in the pH level of groups B, C and D after 14 days of fluoride application (p < 0.05). The non-parametric Kruskal Wallis test was applied for the comparison between the groups. Conclusion: This study concluded that all the fluoride gels after administration caused the acidic pH of saliva with the most acidic effect produced by APF gel (AU).

Surface characteristics of a modified acidulated phosphate fluoride gel with nano-hydroxyapatite coating applied on bovine enamel subjected to an erosive environment.

This study evaluated the antierosive effect applying a modified acidulated phosphate fluoride (APF) gel containing nano-hydroxyapatite (nHAp) on the enamel surface before erosion. After polishing, the exposed flat enamel surfaces (n = 7/group) from bovine incisors were treated with artificial saliva (S - negative control), orange juice (ERO), APF gel (positive control) and APF_nHAp gel. All samples were subjected to six cycles of demineralization (orange juice, pH ~ 3.5, 10 min) followed by remineralization (saliva, 37°C, 1 hr). The enamel surface morphology, topography, and inorganic composition were analyzed using scanning electron microscopy, roughness testing, and micro energy-dispersive X-ray fluorescence spectrometry, respectively. The mean (standard deviation) roughness values (Ra, µm) were S, 0.13 (0.05); ERO, 0.25 (0.07); APF, 0.22 (0.08); and APF_nHAp, 0.17 (0.04). Ra values were significantly higher after ERO (p < .01) and APF (p < .05) treatments than after S. The enamel surface morphology was altered by the treatments, except for the S specimens. The mineral content of the enamel showed a clear trend with Ca and P reduction in the order of APF < S < APF_nHAp < ERO and APF < S < ERO < APF_nHAp, respectively. We can conclude that APF gel increased mineral concentration on the enamel. Moreover, the APF_nHAp material modified the composition and morphology of the enamel surface.

Evaluation of Interactions of Surface Fluorides on Nickel-chromium and Casted Titanium Alloys: An In Vitro Study.

AIM: The present study was conducted to assess the effects of topical fluoride on casted Titanium and nickel chromium using Scanning Electron Microscope. MATERIALS AND METHODS: This in vitro study comprised of 45 specimens of Titanium and 45 specimens of nickel-chromium of same dimensions. They were divided into three groups of 15 each. GroupI specimens were immersed in 2% neutral sodium fluoride (NaF) solution for 16 minutes. Group II specimens were placed in 1.23% acidulated phosphate fluoride (APF) gel for eight minutes. Group III specimens were placed in distilled water for 8 minutes. All specimens were evaluated for surface roughness using a scanning electron microscope. RESULTS: Data thus obtained were subjected to statistical analysis including post-hoc test and analysis variance (ANOVA). There was no significant increase in surface roughness of nickel- chromium specimens in group I, II and III (p > 0.05) whereas Titanium specimens in group II showed a substantial increase in surface roughness (p < 0.05). There was surface corrosion of Titanium specimens and slight pitting of nickel-chromium specimens in group II. CONCLUSION: The studied preparation (1.23%) of acidulated phosphate fluoride has shown to affect the surface roughness of Titanium and nickel-chromium specimens whereas 2% neutral sodium fluoride and distilled water has no noticeable effect, therefore, providing some logical clinical correlations. CLINICAL SIGNIFICANCE: Clinicians must be well known about the logical usages of topical fluorides in dentistry. Different fluoride concentrations and preparations are capable of producing prosthesis's surface roughness of various degrees. Surface roughness is acting as potent areas of bacterial adhesion, plaque retention, calculus retention and microcrack formation with poor esthetics and therefore it significantly affect long-term prosthesis success. Thus, the operator must be very critically monitoring and managing the harmful effects of acidic fluoridated on prosthesis made up of casted Titanium and nickel-chromium.

Measuring the remineralization potential of different agents with quantitative light-induced fluorescence digital Biluminator.

BACKGROUND: The aim of this study was to investigate the effectiveness of different remineralization agents by quantitative light-induced fluorescence digital BiluminatorTM (QLF-D). METHODS: Artificial caries lesions were created, and the teeth were divided according to the tested materials: (i) distilled water, (ii) acidulated phosphate fluoride (APF), (iii) Curodont Repair (CR), (iv) ammonium hexafluorosilicate (SiF) and (v) ammonium hexafluorosilicate plus cetylpyridinium chloride (SiF + CPC). After treatment procedures, each of the samples was placed in artificial saliva. After demineralization and 1 and 4 weeks of remineralization procedures, fluorescence loss and lesion areas were measured with QLF-D. Data were statistically analyzed (α = 0.05). RESULTS:: The fluorescence values of the demineralized enamel specimens treated with the various agents differed significantly compared with pretreatment values for both 1 and 4 weeks (p<0.05). At 4 weeks, the highest fluorescence gain was calculated in the CR, APF and SiF groups compared with the control (p<0.05). CONCLUSIONS:: APF, SiF and CR groups yielded greater remineralization ability than SiF + CPC and control groups.

Corrosion behavior of zirconia in acidulated phosphate fluoride.

OBJECTIVE: The corrosion behavior of zirconia in acidulated phosphate fluoride (APF) representing acidic environments and fluoride treatments was studied. MATERIAL AND METHODS: Zirconia rods were immersed in 1.23% and 0.123% APF solutions and maintained at 37°C for determined periods of time. Surfaces of all specimens were imaged using digital microscopy and scanning electron microscopy (SEM). Sample mass and dimensions were measured for mass loss determination. Samples were characterized by powder X-ray diffraction (XRD) to detect changes in crystallinity. A biosensor based on electrochemical impedance spectroscopy (EIS) was used to detect ion dissolution of material into the immersion media. RESULTS: Digital microscopy revealed diminishing luster of the materials and SEM showed increased superficial corrosion of zirconia submerged in 1.23% APF. Although no structural change was found, the absorption of salts (sodium phosphate) onto the surface of the materials bathed in 0.123% APF was significant. EIS indicated a greater change of impedance for the immersion solutions with increasing bathing time. CONCLUSION: Immersion of zirconia in APF solutions showed deterioration limited to the surface, not extending to the bulk of the material. Inferences on zirconia performance in acidic oral environment can be elucidated from the study.

Corrosion behavior of zirconia in acidulated phosphate fluoride

ABSTRACT Objective The corrosion behavior of zirconia in acidulated phosphate fluoride (APF) representing acidic environments and fluoride treatments was studied. Material and Methods Zirconia rods were immersed in 1.23% and 0.123% APF solutions and maintained at 37°C for determined periods of time. Surfaces of all specimens were imaged using digital microscopy and scanning electron microscopy (SEM). Sample mass and dimensions were measured for mass loss determination. Samples were characterized by powder X-ray diffraction (XRD) to detect changes in crystallinity. A biosensor based on electrochemical impedance spectroscopy (EIS) was used to detect ion dissolution of material into the immersion media. Results Digital microscopy revealed diminishing luster of the materials and SEM showed increased superficial corrosion of zirconia submerged in 1.23% APF. Although no structural change was found, the absorption of salts (sodium phosphate) onto the surface of the materials bathed in 0.123% APF was significant. EIS indicated a greater change of impedance for the immersion solutions with increasing bathing time. Conclusion Immersion of zirconia in APF solutions showed deterioration limited to the surface, not extending to the bulk of the material. Inferences on zirconia performance in acidic oral environment can be elucidated from the study.

Surface degradation of lithium disilicate ceramic after immersion in acid and fluoride solutions.

PURPOSE: To analyze whether immersion in sodium fluoride (NaF) solutions and/or common acidic beverages (test solutions) would affect the surface roughness or topography of lithium disilicate ceramic. METHODS: 220 ceramic discs were divided into four groups, each of which was subdivided into five subgroups (n = 11). Control group discs were immersed in one of four test beverages for 4 hours daily or in artificial saliva for 21 days. Discs in the experimental groups were continuously immersed in 0.05% NaF, 0.2% NaF, or 1.23% acidulated phosphate fluoride (APF) gel for 12, 73, and 48 hours, respectively, followed by immersion in one of the four test beverages or artificial saliva. Vickers microhardness, surface roughness, scanning electron microscopy (SEM) associated with energy dispersive spectroscopy, and atomic force microscopy (AFM) assessments were made. Data were analyzed by nested analysis of variance (ANOVA) and Tukey's test (α = 0.05). RESULTS: Immersion in the test solutions diminished the microhardness and increased the surface roughness of the discs. The test beverages promoted a significant reduction in the Vickers microhardness in the 0.05% and 0.2% NaF groups. The highest surface roughness results were observed in the 0.2% NaF and 1.23% APF groups, with similar findings by SEM and AFM. Acidic beverages affected the surface topography of lithium disilicate ceramic. Fluoride treatments may render the ceramic surface more susceptible to the chelating effect of acidic solutions.

Una década de monitoreo de plomo en sangre en niños escolares del área metropolitana de Monterrey, NL / A decade of lead monitoring in schoolchildren in the metropolitan area of Monterrey NL, Mexico

Objetivo. Establecer las concentraciones de plomo (Pb) en sangre en niños escolares de 1998 y 2008, así como su asociación con factores de riesgo. Material y métodos. Se llevó a cabo un monitoreo de Pb en sangre de niños de entre 6 y 12 años que cursan educación primaria en 17 escuelas diferentes, ubicadas en distintas zonas del área metropolitana de Monterrey, de 1998 a 2008. Resultados. Se obtuvieron niveles séricos de 9.6 ± 3.0 (µg/dL rango de 3.18 a 20.88) en 1998 y de 4.5±4.8 µg/dL (rango de 3.3 a 53.7) en 2008, lo que mostró una disminución de 2.1 veces en nivel de Pb (p<0.01). Conclusiones. La reducción de los niveles séricos de Pb demuestran los mejores controles ambientales e industriales y probablemente el éxito de retirar el Pb de la gasolina durante los años noventa.

Objective. To establish the blood lead concentration and associated risk factors in schoolchildren during 1998 and 2008. Materials and methods. A blood lead screening was conducted in schoolchildren of 6-12 years of age, enrolled in 17 elementary schools of the metropolitan area of Monterrey, México, during 1998 and 2008. Results. The mean blood lead level were 9.6 ± 3.0 (µg/dL range of 3.18 to 20.88) in 1998 and 4.5±4.8 µg/dL (range of 3.3 to 53.7) showing a 2.1-times reduction in blood lead levels (p<0.01). Conclusions. This reduction in blood lead levels demonstrate environmental and industrial control improvements and the benefits of fading out the leaded gasoline during the 1990's.

Surface micromorphological changes of glass ionomer following application of 1.23% acidulated phosphate fluoride: a scanning electron microscope study.

OBJECTIVES: The purpose of this study was to evaluate the surface micromorphological changes of conventional glass ionomer cement (GIC) (Fuji II, GC Corporation, Tokyo, Japan) and high strength, high viscosity GIC (Fuji IX GP, GC Corporation) subjected to 1.23% acidulated phosphate fluoride (APF) gel for 4 min. It also evaluated the surface micromorphological changes that occurred in these materials when they were coated with a layer of glass ionomer varnish prior to the application of 1.23% APF gel. MATERIALS AND METHODS: A total of 60 uniform glass ionomer cylinders were prepared (30 of each Fuji II and Fuji IX) and stored in distilled water for 48 h, following which they were divided into six groups depending on the surface treatment. Group 1: Fuji II alone, Group 2: Fuji IX alone, Group 3: Fuji II + 1.23% APF gel for 4 min, Group 4: Fuji IX + 1.23% APF gel for 4 min, Group 5: Fuji II + varnish + 1.23% APF gel for 4 min, and Group 6: Fuji IX + varnish + 1.23% APF gel for 4 min. After the required surface treatment had been done, the specimens were mounted, coated, and evaluated under scanning electron microscope. STATISTICAL ANALYSIS: Kruskal-Wallis test applied to compare the level of degradation among the groups subjected to treatment was highly significant (P < 0.001). Mann-Whitney test was applied to test the association between glass ionomer varnish and level of surface degradation and was also statistically significant (P = 0.001). RESULTS: The results indicated that APF gel etched the surface of both Fuji II and Fuji IX. However, Fuji IX showed to possess better resistance to the erosive effect of APF than Fuji II. It was also observed that application of glass ionomer varnish prior to APF gel application protected the glass ionomer from the erosive effect of APF gel. CONCLUSION: APF gel caused erosive wear of the GICs esp. Fuji II. Hence, it is advisable to avoid the use of APF containing preparations for regular home use especially in children having glass ionomer restoration. If APF gel is indicated or preferred for professional application, it is recommended to apply glass ionomer varnish on the restored teeth prior to the APF gel application.

In vitro evaluation of topical fluoride pH and their effect on surface hardness of composite resin-based restorative materials.

AIM: The aim of the study was to correlate the pH and fluoride ion uptake with surface hardness of composite resin based restorative materials after topical fluoride application. METHODOLOGY: Forty disks of each of test materials Composite (Filtek Z350XT, 3M ESPE, St Paul, MN, USA), Resin modified glass ionomer (Vitremer) and Compomer (Dyract AP) were made and ten disks of each material were placed in different test solutions - 1.23% APF gel, Sodium fluoride mouth rinse, 0.9% neutral fluoride and distilled water (Control group). After 36 hours of immersion, specimens were subjected to microhardness testing machine for evaluation of surface hardness. RESULTS: The greater hardness deterioration for all materials resulted with 1.23% APF gel when compared to the control group. Composite (Filtek Z350XT, 3M ESPE, St Paul, MN, USA) showed 17.13 VHN (control group 59.11 VHN). Vitremer showed 9.71 VHN (control group 37.71 VHN). Compomer showed 19.22 VHN (control group 36.78 VHN). CONCLUSION: 1.23% ApF gel significantly decreased hardness of composite, Vitremer and Compomer. Hardness deterioration associated with sodium fluoride mouth rinse and 0.9% neutral fluoride was less compared to 1.23% ApF gel.

Fluoride release from fluoride varnishes under acidic conditions.

OBJECTIVE: The aim was to investigate the in vitro fluoride release from fluoride varnishes under acidic conditions. STUDY DESIGN: Poly(methyl methacrylate) blocks (Perspex, n=3 per group) were painted with 80 ± 5 mg fluoride varnish (n=10) and placed into artificial saliva for 30 min. Then, blocks were placed into either 1% citric acid (pH 2.27) or 0.3% citric acid (pH 3.75) solutions (n=3 per solution and varnish) for 30 min with the solutions being replaced every 5 min. Saliva and acid solutions were analyzed for fluoride content. Data were analyzed using three-way ANOVA (varnish, solution, time). RESULTS: The three-way interaction was significant (p>0.0001). Fluoride release and release patterns varied considerably between varnishes. Fluoride release in saliva varied by a factor of more than 10 between varnishes. Some varnishes (CavityShield, Nupro, ProFluorid, Vanish) showed higher fluoride release in saliva than during the first 5 min of acid exposure, whereas other varnishes (Acclean, Enamel-Pro, MI Varnish, Vella) showed the opposite behavior. There was little difference between acidic solutions. CONCLUSIONS: Fluoride release from fluoride varnishes varies considerably and also depends on the dissolution medium. Bearing in mind the limitations of laboratory research, the consumption of acidic drinks after fluoride varnish application should be avoided to optimize the benefit/risk ratio.

Surface roughness of fluoride-releasing restorative materials after topical fluoride application.

AIM: The aim of this study was to assess the effect of a single application of two topical fluoride agents: NNaF and APF (2% neutral sodium fluoride gel and 1.23% acidulated phosphate fluoride gel, respectively) on the surface roughness (Ra) of Fuji IX GP, Ketac N100, Vitremer, Dyract AP, Compoglass F and Filtek Ultimate. STUDY DESIGN: The effect of NNaF and APF on the surface roughness of fluoride-releasing restorative materials was tested on disk-shaped material specimens with a surface profilometer. METHODS: All materials were handled according to manufacturer's instructions. ISO standardised specimens were prepared for each material and then stored in distilled water for 24 hr. Each sample was polished with 600 and 1200 grit sandpaper on both sides while keeping the material surface wet. Ra measurements were performed on untreated specimens initially and after 1 min, 4 min and simulated 2-years for both fluoride applications, respectively. The mean Ra values for all specimens were measured using a surface profilometer. STATISTICS: Differences in surface roughness values were assessed using paired t-test. The differences between the experimental groups were analysed with one-way ANOVA; p<0.05 was accepted as statistically significant. RESULTS: The results of the present study indicated that Ra values for Fuji IX GP and Vitremer increased significantly after all APF, but not NNaF applications. All tested materials exhibited increased Ra values for both treatment regimes, but this was not found statistically significant. CONCLUSION: APF gel application significantly increased the surface roughness of both Fuji IX GP and Vitremer for all time periods.

Differences in loosely bound fluoride formation and anticaries effect of resin-based fluoride varnishes.

OBJECTIVE. Our in vitro study evaluated calcium fluoride formation in enamel and the anticaries effect of seven resin-based varnishes under cariogenic challenge. METHODS. Enamel blocks were subjected to pH cycling. The experimental groups received fluoride varnish application, the positive control received topical fluoride gel treatment, and the negative control did not receive any treatment. The pH cycling surface hardness (SH1 ) and integrated loss of subsurface hardness (ΔKHN) were then determined. We measured the amount of fluoride released into the demineralizing and remineralizing (DE-RE) solutions used in pH cycling. The fluoride concentration in the enamel was determined 24 h after application of the products as loosely bound fluoride and firmly bound fluoride. RESULTS. Higher deposits of loosely bound fluoride were observed for Duofluorid, followed by Biophat. For Duraphat, Bifluorid, Duraflur, and Duofluorid, no difference was observed in the SH1 and ΔKHN values, with the lowest mineral loss compared to the other groups. The Bifluorid and Duofluorid groups released high fluoride amounts into the DE-RE, and statistically significant difference was noted between them. CONCLUSIONS. The anticaries effect showed no correlation with higher deposited fluoride amounts, resin type, or fluoride source.

Fluoride releasing and uptake capacities of esthetic restorations.

BACKGROUND AND OBJECTIVES: The purpose of this study was to evaluate and compare in vitro the fuoride release and uptake from 5 different esthetic restorative materials. MATERIALS AND METHODS: Materials tested were conventional GIC - Fuji 7, GC (group1), resin modifed GIC - Vitremer, 3M ESPE (group 2), polyacid modifed composite - Dyract, Dentsply (group 3), fuoride releasing composite - Tetric ceram, Ivoclar Vivadent (group 4), Giomer-Beautifl, Shofu (group 5). Fluoride release was estimated at 6th, 24th, 48th hour and weekly interval for 5 weeks. For fuoride recharge, each specimen was exposed to 2 ml of 1.23% APF gel for 4 minutes and fuoride release measured at 1st, 2nd, 3rd day and 7th day. The fuoride release and recharge was measured using fuoride ion specifc electrode. RESULTS: ANOVA and Tukey HSD test were used for statistical analysis. During tested period all materials showed statistically different capability to release and uptake fuoride. Groups 1 and 2 results were comparable in fuoride release. Similarly groups 3 and 5. Groups 1 and 2 vs 3, 4, 5 were statistically very highly signifcant. Only conventional GIC showed initial 'burst effect'. INTERPRETATION AND CONCLUSION: Materials tested showed potential for fuoride release and recharge. Different esthetic materials had variable fuoride release hence selection of materials should be guided by specifc clinical situations.

Breaking the fluoride diffusion barrier with combined dielectrophoresis and AC electroosmosis.

PURPOSE: To compare the deposition of fluoride particles into bovine enamel by diffusion (n = 20); dielectrophoresis (DEP) at 10 Hz and 5000 Hz (n = 10); and DEP (10 Hz and 5000 Hz) combined with AC electroosmosis (ACEO) at 400 Hz (DEP/ACE) (n = 10). METHODS: Fluoride particle movements induced at 10, 400, and 5000 Hz frequencies, were analyzed with light microscopy and stack imaging in real time. Fluoride concentrations were measured at various enamel depths using wavelength dispersive spectrometry. Results were analyzed by ANOVA/Student-Newman-Keuls post hoc (P = 0.05). RESULTS: Fluoride levels in teeth treated with DEP were significantly higher than diffusion at depths 10 and 20 microm. DEP and diffusion were relatively ineffective at greater depths. The highest fluoride concentrations at 10, 20, and 50 microm depths were found in the DEP/ACE group. After 20 minutes, DEP/ACE increased fluoride uptake by 600% at 50 microm and 400% at 100 microm compared to baseline levels (P < 0.05). Fluoride particle movement was induced by negative DEP at 10 Hz; positive DEP at 5000 Hz; and ACEO at 400 Hz frequency.

Effect of fluoride prophylactic agents on the surface topography of NiTi and CuNiTi wires.

AIM: The aim of this study was to see the effect of topical fluoride on surface texture on nickel-titanium and copper-nickel-titanium orthodontic archwires. MATERIALS AND METHODS: Preformed rectangular NiTi and CuNiTi wires were immersed in in fluoride solution and artificial saliva (control) for 90 minutes at 37°C. after immersion optical microscope was used to see the fluoride effect on the wire topography. RESULTS: The acidulated fluoride agents appeared to cause greater corrosive effects as compared to the neutral fluoride agents. CONCLUSION: The result suggest that using topical fluoride agents leads to corrosion of surface topography indirectly affecting the mechanical properties of the wire that will lead to prolonged orthodontic treatment. CLINICAL SIGNIFICANCE: The use of topical fluoride agents has to be limited in patients with prolonged orthodontic treatment as it causes the corrosion of the NiTi and CuNiTi wires.

Microhardness and surface roughness of glass ionomer cements after APF and TiF4 applications.

OBJECTIVE: To evaluate whether TiF4 solution and APF gel had any adverse effects on the surface morphology of newly developed glass ionomers. STUDY DESIGN: Fifteen disc-shaped specimens of Fuji IX Extra, Fuji II LC and Ketac N100 were prepared and stored in 2 ml of artificial saliva at 37 degrees C for 8 weeks. Specimens of each material were divided randomly into three subgroups as 1 and 4 minutes application of 1.23% APF gel and 1 minute application of 1% TiF4 solution. Specimens were reaged for another 8 weeks. Microhardness, surface roughness values and surface morphology were evaluated by using Vicker's hardness test, surface profilometry and scanning electron microscopy (SEM) for all time interventions, respectively. One-way Anova test was performed and differences were compared by Tukey's HSD and Dunnet T3 test RESULTS: APF and TiF4 applications decreased microhardness significantly in Fuji II LC. In Fuji IX Extra microhardness decreased significantly after 1- and 4-min APF applications. Ketac N100 showed no difference in microhardness after APF and TiF4 applications. Surface roughness was not affected at any time interval for three restorative materials. CONCLUSION: Within the limitations of this vitro study it was revealed that, potential adverse effects of APF and TiF4 applications might be material dependant. Hence, restorative materials should be selected in accordance with kind, frequency and application time of fluoridation to avoid deteriorations of the restorations.

Effect of fluoride solutions on the shear bond strength of orthodontic brackets.

The aim of this in vitro study was to evaluate the shear bond strength of brackets after pre-treatment with different fluoride solutions. This study used 48 freshly extracted sound bovine incisors that were randomly assigned to 4 experimental groups (n=12). CG: (control) without treatment; NF: 4 min application of neutral fluoride; APF: application of 1.23% acidulated phosphate fluoride (APF) for 4 min; and SFV: application of 5% sodium fluoride varnish for 6 h. For each group, after surface treatment, prophylaxis of enamel and bracket bonding with Transbond XT composite resin (3M) were performed following the manufacturer's specifications. The shear bond strength was performed with a universal testing machine 24 h after fixing the brackets. The tooth surfaces were analyzed to verify the adhesive remnant index (ARI). Data were analyzed statistically by ANOVA and Tukey's test (α=0.05). There was statistically significant difference among the groups (p<0.0001). CG and NF groups presented significantly higher bond strength than APF and SFV. There was no significant difference between CG and NF or between APF and SFV (p>0.05). The analysis of ARI scores revealed that most failures occurred at the enamel-resin interface. It may be concluded that the pre-treatment of enamel with 1.23% APF and 5% SFV prior to fixing orthodontic brackets reduces shear bond strength values.

Effect of fluoride solutions on the shear bond strength of orthodontic brackets

The aim of this in vitro study was to evaluate the shear bond strength of brackets after pre-treatment with different fluoride solutions. This study used 48 freshly extracted sound bovine incisors that were randomly assigned to 4 experimental groups (n=12). CG: (control) without treatment; NF: 4 min application of neutral fluoride; APF: application of 1.23% acidulated phosphate fluoride (APF) for 4 min; and SFV: application of 5% sodium fluoride varnish for 6 h. For each group, after surface treatment, prophylaxis of enamel and bracket bonding with Transbond XT composite resin (3M) were performed following the manufacturer's specifications. The shear bond strength was performed with a universal testing machine 24 h after fixing the brackets. The tooth surfaces were analyzed to verify the adhesive remnant index (ARI). Data were analyzed statistically by ANOVA and Tukey's test (α=0.05). There was statistically significant difference among the groups (p<0.0001). CG and NF groups presented significantly higher bond strength than APF and SFV. There was no significant difference between CG and NF or between APF and SFV (p>0.05). The analysis of ARI scores revealed that most failures occurred at the enamel-resin interface. It may be concluded that the pre-treatment of enamel with 1.23% APF and 5% SFV prior to fixing orthodontic brackets reduces shear bond strength values.

O objetivo deste estudo foi o de avaliar in vitro a resistência adesiva de bráquetes após o pré-tratamento do esmalte com diferentes soluções fluoretadas. Foram utilizados 48 incisivos bovinos hígidos recém-extraídos que foram aleatoriamente divididos em 4 grupos experimentais (n=12). CG (controle): sem tratamento; FN: aplicação de flúor neutro por 4 min; FFA: aplicação de flúor fosfato acidulado (FFA) a 1,23% por 4 min; e VFS: aplicação de verniz de fluoreto de sódio a 5% por 6 h. Após o tratamento dos grupos, foi realizada a profilaxia do esmalte e os bráquetes foram fixados utilizando o compósito Transbond XT (3M), seguindo as especificações do fabricante. A resistência adesiva foi verificada através do teste de cisalhamento, realizado na Máquina de Ensaio Universal DL-2000 24 h após a fixação dos bráquetes. As superfícies dos dentes foram analisadas para verificação do índice de adesivo remanescente (IAR). Por meio dos testes estatísticos ANOVA e Tukey (α=5%), observou-se diferença estatisticamente significante entre os grupos estudados (p<0,0001), sendo que GC e FN, apresentaram valores superiores de resistência adesiva quando comparados aos grupos FFA e VFS, porém GC-NF e FFA-VFS não apresentaram diferenças estatisticas entre si (p>0,05). A análise dos escores do IAR revelou que grande parte das falhas ocorreram na interface esmalte-resina. Conclui-se que o tratamento do esmalte com FFA 1,23% e VFS a 5%, previamente à fixação de bráquetes ortodônticos, reduziu os valores de resistência adesiva ao cisalhamento.

Effect of a two-year fluoride decay protection protocol on titanium brackets.

INTRODUCTION: Fluoride ion can attack titanium, causing its corrosion. Orthodontic patients being high-risk caries developers and in need of fluoride protection, the Center for Disease Control has developed a Fluoride Decay Prevention (FDP) protocol, consisting of a 6-minute tooth-brushing, followed by a 1-minute daily mouthwash, in addition to an in-clinic trimestrial topical fluoride gel application. This study aimed at evaluating gravimetrically, by scanning electron microscopy (SEM), and by sliding mechanics analysis, the consequences of FDP at 6, 12, 18, and 24months on titanium brackets corrosion. METHODS: One hundred and fifty titanium brackets were randomly divided into five groups of 30. Group 1 was the control group. Groups 2, 3, 4, and 5 each received an equivalent of 6, 12, 18, and 24months of FDP treatment respectively. All groups were placed in artificial saliva for 2months and then rinsed. Subsequently, the brackets were dried, for 48hours, using Silica gel in a desiccator maintained at 37°C before testing. RESULTS: SEM analysis showed that numbers and dimensions of pits gradually increased due to corrosion as we moved from group 1 to group 5. Gravimetrical and sliding mechanics results revealed no statistical difference between groups 2 and 3, and a significant difference between groups 4 and 5 upon comparison with the control group. CONCLUSION: Surface changes due to corrosion were detected at 6 and 12months of FDP but had no clinical effects. However, the increase in sliding resistance and bracket weight loss became significant at 18 and 24months of FDP.