Assessment of the preventive effects of Nd:YAG laser associated with fluoride on enamel caries using optical coherence tomography and FTIR spectroscopy.

OBJECTIVE: This in vitro study characterized and monitored, by Optical Coherence Tomography (OCT) and Fourier Transformed Infrared Spectroscopy (FTIR), the effects of the association of acidulated phosphate fluoride gel (APF-gel) and Nd:YAG (neodymiun:yttrium-aluminum-garnet) laser, as sequencial treatments, in the prevention of incipient enamel caries lesions. METHODS: 120 human enamel samples were randomized into 3 groups (n = 40): APF-gel (1.23% F-, 4 min.); Laser+APF (Nd:YAG laser irradiation-0.6W, 84.9J/cm2, 10Hz, followed by APF-gel); and APF+Laser (APF-gel followed by laser irradiation). The samples were subjected to a 15-day pH-cycling, evaluated by OCT (quantification of optical attenuation coefficient-OAC) and FTIR (analysis of carbonate and phosphate content) before treatments, after treatments, and on the 5th, 10th and 15th days of pH-cycling. The statistical analysis was performed (α = 5%). RESULTS: The Optical Attenuation Coefficient (OAC) assessed by OCT increases with the progression of demineralization, and the Laser+APF presented the highest values of OAC in 10th and 15th days of pH-cycling. Nd:YAG decreased the carbonate content after treatment regardless of the application order of the APF-gel, while APF-gel did not interfere in the composition of enamel. The carbonate content was also changed in the first 5 days of the pH-cycling in all groups. CONCLUSION: Nd:YAG laser irradiation before or after the application of APF-gel did not influence the appearance of incipient caries lesions, showing no synergistic effect. Regardless of the application order of the APF-gel, laser irradiation reduces the carbonate content of the enamel, which also changes during the demineralization process. However, irradiation before the application of APF-gel increased the speed of progression of the lesions, which positively impacts public health as it can prevent caries disease, even in high risk individuals. OCT and FTIR are suitable for assessing this effect.

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.

Retention Improvement in Fluoride Application with Cold Atmospheric Plasma.

This study aimed to apply fluoride formulations to enamel with cold atmospheric plasma (CAP) and analyze the fluoride uptake, retention, and acid resistance quantitatively. Human enamel specimens were divided randomly into 2 groups: group APF1, 1.23% acidulated phosphate fluoride (APF) gel; group APF2, 1.23% APF gel with CAP. Fluoride and CAP were applied to the samples 4 times at 1-wk intervals. The specimens were also stored in artificial saliva for 4 wk to evaluate the retention of fluoride. The fluoride content on the fluoride-treated enamel was measured by an electron probe microanalyzer. To detect the resistance to demineralization, the calcium-to-phosphate ratio of the enamel samples was measured after the application of APF gel with or without CAP, followed by soaking in the demineralization solution. In groups APF1 and APF2, the amount of fluoride detected increased depending on the application frequency, and more fluoride was detected in group APF2 than in group APF1. In the experiment examining the maintenance effect, fluoride was not detected in group APF1, whereas fluoride was detected in group APF2 up to the fourth week. As for the resistance to demineralization, the calcium-to-phosphate ratio of the enamel treated with APF and CAP was higher than that treated with APF alone, and it increased with the frequency of treatment. This study suggests that the combination treatment of CAP and fluoride improves retention of fluoride on the enamel and resistance to demineralization when compared with treatment with fluoride alone.

Assessment of the Influence of Meal Type on Fluoride Absorption due to Ingestion of professionally Applied Gels.

AIMS: The aim of this study is to assess the influence of eating, prior to application of professionally used gels, on the rate of fluoride absorption due to the ingestion of 1.23% acidulated phosphate fluoride (APF). MATERIALS AND METHODS: After fasting for 12 hours, 16 adult volunteers (> 65 kg) ingested two types of meal: Breakfast (n = 8) and Lunch (n = 8). Accidental ingestion of fluoride gel used in molding trays was simulated (12,300 ppm; 61.5 mg F; pH = 4.65) 15 minutes after eating. After ingestion of the fluoride solution, 3 mL of venous blood were collected at the following times: Zero (before ingestion) and 15, 30, 45 minutes, 1, 2, and 3 hours. Fluoride concentrations in blood plasma were determined using an ion selective electrode. RESULTS: With the exception of time 0 (p > 0.05), the average blood plasma concentration of the breakfast group (BG) (0.34 ± 0.04 mg/L) was higher than that of the lunch group (LG) (0.24 ± 0.03 mg/L), with the moment of peak concentration being 2 hours after ingestion for both groups (BG = 0.4 mg/L; LG = 0.28 mg/L). CONCLUSION: Results reinforce the idea that eating before undergoing professional application of fluoride is a factor of extreme importance regarding its safety, and that the time following a patient's heaviest meal should be the time of choice for planning clinical care. CLINICAL SIGNIFICANCE: Our results should be considered when planning collective action that involves the application of the gel on children in a school environment, thus ensuring the procedure's safety.

Does fluoride gel/foam application time affect enamel demineralization?

The American Dental Association Council on Scientific Affairs recommends a four-minute application of professionally applied topical fluoride, based on clinical evidence for caries reduction. However, some product manufacturers imply that a one-minute application is sufficient. The purpose of this laboratory study was to ascertain if a one-minute application of acidulated phosphate fluoride (APF) is equivalent to a four-minute application for reduction of enamel demineralization. We measured baseline hardness of polished bovine enamel before treatment with APF gel or foam for one or four minutes (N = 10). A control group received no fluoride treatment. The teeth were then immersed in pooled human saliva for 30 minutes, rinsed, and subjected to lactic acid gel to simulate the initial stage of dental caries. After three hours, the hardness was measured and the difference in hardness was determined as an indication of demineralization. We found that enamel hardness was significantly reduced after exposure to lactic acid gel. The reduction was significantly less in all APF-treatment groups compared to the control. However, there was no significant difference between a tooth exposed to APF gel or foam for 1 minute or for 4 minutes (ANOVA/Student-Newman-Keuls, significance level 0.05). In conclusion, APF gel and foam reduced enamel demineralization regardless of a one- or four-minute application time.

Enhanced penetration of fluoride particles into bovine enamel by combining dielectrophoresis with AC electroosmosis.

Fluoride deposition into the pores of enamel is necessary at high concentrations to reduce enamel demineralization and with a high degree of penetration to account for loss by ingestion. Current diffusion and electrochemical methods are inadequate for effectively transporting fluoride greater than 20 µm into enamel. The study explores the coupling of dielectrophoresis (DEP) and AC electroosmosis (ACEO) to selectively concentrate fluoride particles from fluoride gel excipients and enhance their penetration into enamel. By measuring the frequency response of approximately 10-µm-sized sodium fluoride particles in an aqueous gel media, appropriate frequencies for positive DEP, negative DEP, and ACEO are identified. An assembly composed of two cross-planar interdigitated electrode (IDE) arrays with open slots is driven successively by fields at appropriate frequencies to drive fluoride particles through the slots of the IDE and into the enamel pores using a combination of DEP and ACEO methods. Fluoride uptake and penetration of 1.23% acidulated phosphate fluoride gel into bovine tooth enamel at various depths is measured using wavelength dispersive spectrometry to compare deposition by diffusion, DEP, and DEP plus ACEO. Fluoride levels in all DEP groups were significantly higher than diffusion groups at depths 10 and 20 µm. The highest fluoride concentrations at 10, 20, 50, and 100 µm depths occur under deposition conditions combining DEP with ACEO. Fluoride levels at 50 µm were equivalent to long-term prophylactic exposure. These methods may potentially benefit populations at high risk for development of caries and periodontal disease, including underserved children and disparate groups.

Efficacy of 1.23% APF gel applications on incipient carious lesions: a double-blind randomized clinical trial.

The aim of this double-blind randomized clinical trial was to evaluate the efficacy of 1.23% APF gel application on the arrest of active incipient carious lesions in children. Sixty 7- to 12-year-old children, with active incipient lesions were included in the study. Children were divided randomly into 2 groups: 1.23% APF gel and placebo gel applications. Each group received 8 weekly applications of treatment. The lesions were re-evaluated at the 4th and 8th appointments. Poisson regression analysis was used to estimate relative risks of the presence of active white spot lesions. Groups showed similar results (PR = 1.67; CI 95% 0.69-3.98). The persistence of at least 1 active lesion was associated with a higher number of lesions in the baseline (PR = 2.67; CI 95% 1.19-6.03), but not with sugar intake (PR = 1.06; CI 95% 0.56-2.86) and previous exposure to fluoride dentifrice (PR = 1.26; CI 95% 0.49-2.29). The trial demonstrates the equivalence of the treatments. The use of the APF gel showed no additional benefits in this sample of children exposed to fluoridated water and dentifrice. The professional dental plaque removal in both groups may also account for the resulting equivalence of the treatments.

Effect of 1.23% acidulated phosphate fluoride foam on white spot lesions in orthodontic patients: a randomized trial.

PURPOSE: The decalcification of enamel is a serious clinical problem in orthodontic patients and is usually observed as white spot lesions surrounding brackets. This study's purpose was to evaluate the effect of professionally applied 1.23 percent fluoride foam on reducing the formation of white spot lesions (WSLs) in patients with fixed orthodontic appliances. METHODS: In a randomized, double-blind, placebo-controlled trial, 100 participants were randomly divided into two groups. The two groups received fluoride foam and placebo foam, respectively, every two months during the treatment. The examinations before bonding and after debonding were performed by one examiner and included the presence and severity of WSLs on incisors, canines, and premolars. RESULTS: The incidence of WSLs was approximately 13 percent in the fluoride foam group and 51 percent in the placebo group (P<.001). The mean increment of WSLs score was significantly lower in the fluoride foam group (0.71 ± 2.80) than in the placebo group (4.36 ± 5.41; P<.001). The preventive fraction was approximately 76 percent, and the number needed to treat was calculated as 2.6. CONCLUSIONS: Professional application of 1.23 percent fluoride foam during orthodontic treatment effectively reduced the development of white spot lesions. A prophylactic regimen based on the routine use of fluoride foam during orthodontic treatment is recommended.

Efficacy of 1.23% APF gel applications on incipient carious lesions: a double-blind randomized clinical trial

The aim of this double-blind randomized clinical trial was to evaluate the efficacy of 1.23% APF gel application on the arrest of active incipient carious lesions in children. Sixty 7- to 12-year-old children, with active incipient lesions were included in the study. Children were divided randomly into 2 groups: 1.23% APF gel and placebo gel applications. Each group received 8 weekly applications of treatment. The lesions were re-evaluated at the 4th and 8th appointments. Poisson regression analysis was used to estimate relative risks of the presence of active white spot lesions. Groups showed similar results (PR = 1.67; CI 95% 0.69–3.98). The persistence of at least 1 active lesion was associated with a higher number of lesions in the baseline (PR = 2.67; CI 95% 1.19–6.03), but not with sugar intake (PR = 1.06; CI 95% 0.56–2.86) and previous exposure to fluoride dentifrice (PR = 1.26; CI 95% 0.49–2.29). The trial demonstrates the equivalence of the treatments. The use of the APF gel showed no additional benefits in this sample of children exposed to fluoridated water and dentifrice. The professional dental plaque removal in both groups may also account for the resulting equivalence of the treatments.

Salivary retention after application of fluoride gel using toothbrush or tray: a crossover trial

Currently, there are no studies in the literature evaluating salivary fluoride retention after small amounts of fluoride gel are applied to children's teeth. Therefore, the objective of the present study was to compare salivary retention after gel application using a toothbrush or by traditional application with trays. In this crossover study, children with active caries (n = 10) were randomized into one of the following treatment groups: a) application of fluoride gel using a tray (control), or b) application of fluoride gel with a toothbrush (treatment). After a 7-day washout period, the treatments were inverted. Unstimulated saliva samples were collected at baseline and 0.5, 5, 15, 30, 60 and 120 minutes after acidulated phosphate fluoride (APF) gel application in order to analyze fluoride retention in saliva. The area under the curve (AUC) was also calculated. There were no differences in fluoride retention after application of small amounts of APF with a toothbrush compared to traditional gel application using trays at all time points studied, and no differences in AUC were observed (Student t-test, p > 0.05). These results suggest that application of fluoride gel in children using a toothbrush can be utilized as an option rather than traditional trays, since the same salivary retention of fluoride is obtained using a lower dose.

Salivary retention after application of fluoride gel using toothbrush or tray: a crossover trial.

Currently, there are no studies in the literature evaluating salivary fluoride retention after small amounts of fluoride gel are applied to children's teeth. Therefore, the objective of the present study was to compare salivary retention after gel application using a toothbrush or by traditional application with trays. In this crossover study, children with active caries (n = 10) were randomized into one of the following treatment groups: a) application of fluoride gel using a tray (control), or b) application of fluoride gel with a toothbrush (treatment). After a 7-day washout period, the treatments were inverted. Unstimulated saliva samples were collected at baseline and 0.5, 5, 15, 30, 60 and 120 minutes after acidulated phosphate fluoride (APF) gel application in order to analyze fluoride retention in saliva. The area under the curve (AUC) was also calculated. There were no differences in fluoride retention after application of small amounts of APF with a toothbrush compared to traditional gel application using trays at all time points studied, and no differences in AUC were observed (Student t-test, p > 0.05). These results suggest that application of fluoride gel in children using a toothbrush can be utilized as an option rather than traditional trays, since the same salivary retention of fluoride is obtained using a lower dose.

Microhardness recovery of demineralized enamel after treatment with fluoride gel or CPP-ACP paste applied topically or with dielectrophoresis.

PURPOSE: To evaluate the microhardness of demineralized enamel remineralized in saliva after applying 1.23% APF gel or CCP-ACP paste with dielectrophoresis (DEP) or diffusion for 3 minutes. METHODS: In this laboratory study, 25 enamel blocks of bovine incisors were soaked in demineralizing solution (10 mM HCl pH 2.5) for 10 minutes and remineralized in saliva for 1 hour, after applying 1.23% APF gel or CPP-ACP paste without fluoride with dielectrophoresis or conventional topical application for 3 minutes. The mean and percentage changes of surface microhardness in pre-demineralization, post-demineralization and remineralization stages were measured in the five groups. The results of all five groups during the three stages were compared by ANOVA and paired t-tests (P = 0.05). RESULTS: The average surface microhardness recovery of APF gel (12,300 ppm fluoride) applied with DEP was higher than APF gel applied topically, or CPP-ACP paste applied with DEP or topically, and water control (P < 0.05). The percentage of surface microhardness recovery for APF+DEP, APF+Diffusion, CPP-ACP+DEP, CPP-ACP+Diffusion, and water control were 88.17%, 13.62%, 7.14%, 5.45%, and 4.02%, respectively. Demineralization treatment decreased the surface microhardness of enamel in all groups and the surface microhardness recovery in the APF+DEP group was significant (P < 0.001). The only significant paired difference was between APF+DEP and all other groups. No other paired difference approached significance. Surface microhardness recovery of enamel with APF+DEP was 12 times or 1,200% greater than APF gel applied topically, and CPP-ACP paste either applied topically or with DEP in one 3-minute application.

Dielectrophoresis: a model to transport drugs directly into teeth.

The article describes an innovative delivery system based on the principles of dielectrophoresis to transport drugs directly into site-specific intraoral targets. The hypothesis that a drug can be driven into tooth enamel during the application of an applied electrical potential difference was tested by the authors in in vitro studies comparing dielectrophoresis to diffusion to transport carbamide peroxide and fluoride. The studies showed that these agents can be transported directly into teeth using an alternating current (AC) electric field more effectively than diffusion. It was found that a 20-min bleaching treatment on human teeth with dielectrophoresis increased carbamide peroxide absorption by 104% and, on average, improved the change in shade guide unit 14 times from 0.6 SGU to 9 SGU. After applying a 1.23% acidulated phosphate fluoride gel to bovine incisors for 20 min by dielectrophoresis or diffusion, analysis with wavelength dispersive spectrometry determined that dielectrophoresis doubled fluoride uptake in the superficial layers compared to diffusion, and drove the fluoride significantly deeper into enamel with an uptake 600% higher than diffusion at 50 µm depth. Finally, dielectrophoresis promises to be a viable model that can potentially be used clinically to deliver other targeted drugs of variable molecular weight and structure.

Effect of acidulated phosphate fluoride gel application time on enamel demineralization of deciduous and permanent teeth.

Although the effect of acidulated phosphate fluoride gel (APF gel) on caries reduction in permanent teeth is based on evidence, the relevance of the clinical application time is still under debate. Also, the effect of 4- versus 1-min application has not been evaluated in deciduous enamel. In a blind, crossover, in situ study of 14 days, 16 adult volunteers wore palatal appliances containing slabs of human permanent and deciduous enamel. At the beginning of each phase, the slabs were submitted to one of the following treatments: no APF application (negative control); APF gel (1.23% F) application for 1 or 4 min. Biofilm accumulation on the slab surface was allowed and the slabs were subjected eight times a day to 20% sucrose, simulating a high cariogenic challenge condition. On the 15th day of each phase, fluoride retained as CaF(2) and fluorapatite (FAp) was determined on the enamel of the slabs and demineralization was assessed by cross-sectional microhardness. Fluoride as CaF(2) and FAp, formed by APF gel application on the enamel slabs not subjected to the cariogenic challenge, was also determined. APF gel reduced demineralization in both enamel types (p < 0.05), but the difference between 1 and 4 min was not statistically significant (p > 0.05). CaF(2) and FAp formed and retained on deciduous and permanent enamel was significantly higher in APF gel groups (p < 0.05), but no significant difference was found between 1 and 4 min (p > 0.05). The findings suggest that 1 min of APF gel application provides a similar effect on inhibition of demineralization as 4 min, for both permanent and deciduous enamel.

Effect of fluoride gels on occlusal fissures in primary molars: an in vitro study.

AIM: To assess the effect of the application of fluoride gels on the acid resistance of occlusal enamel in primary molars. STUDY DESIGN: Forty-five primary second molars were randomly assigned to three groups: a) control (pH-cycling); b) 2% NaF gel/pH-cycling; and c) 1.23% APF gel/pH-cycling. METHODS: Specimens were longitudinally sectioned in the buccal-lingual direction and used for cross-sectional microhardness testing. Knoop hardness values were converted into vol.% mineral and mineral loss (ΔZ) was then calculated. STATISTICS: The response variables were vol.% mineral and ΔZ. Data were tested using parametric tests at a significance level of 5%. RESULTS: No statistically significant differences were found between groups regarding vol.% mineral or ΔZ. CONCLUSIONS: A single application of a high concentration fluoride compound does not promote greater resistance to demineralisation in enamel pits and fissures, regardless of the product used.

Effects of periodic fluoride treatment on fluoride ion release from fresh orthodontic adhesives.

OBJECTIVE: Periodic fluoride treatment may contribute to the ability of fresh orthodontic adhesives to provide long-term F(-) release. The effects of periodic fluoride treatment on the amount of F(-) release from fresh orthodontic adhesives was investigated. METHODS: F(-) release was measured from a nonfluoride-releasing composite, a fluoride-releasing composite, a polyacid-modified composite (compomer), and two resin-modified glass-ionomer cements (RMGICs) at 1, 2, and 5 days after one of the following treatments: 225 ppm F(-) solution, 900 ppm F(-) solution, acidulated phosphate fluoride gel (APF), fluoridated dentifrice, and deionised water (control). F(-) release was measured in a 5-day cycle, which was repeated 9 consecutive times. The amount of F(-) release for each group was analysed using the repeated measures analysis of variance. Statistical significance was set at a level of α=0.05. RESULTS: Periodic fluoride treatment temporarily increased F(-) release in fresh fluoride-releasing orthodontic adhesives, but not in fresh nonfluoride-releasing composite. The order of effective fluoride-release was RMGICs>compomer>fluoride-releasing composite>nonfluoride-releasing composite. The application of APF or 900 ppm F(-) solution was the most effective way to maintain F(-) release from fresh orthodontic adhesives. However, the amount of F(-) release gradually decreased with increasing specimen age. CONCLUSION: Given the difficulty of routine use of APF at home, the results of this study show that a combination of RMGICs and high-dose fluoride mouth rinse is the most effective protocol to maintain F(-) release from fresh orthodontic adhesives. CLINICAL SIGNIFICANCE: Most studies have investigated fluoride-uptake abilities using aged materials in which fluoride had been lost for at least 1 month. This study has found that periodic fluoride treatment altered the conventional F(-) release pattern of fresh fluoride-releasing materials and type of fluoride-containing medium plays a more critical role in fluoride recharging of the materials than fluoride concentration. This study will help clinicians to find the most effective fluoride treatment protocol of fresh materials.

Feasibility of including APF gel application in a school oral health promotion program as a caries-preventive agent: a community intervention trial.

A community intervention trial was conducted to assess the feasibility of APF gel as a caries-preventive agent in a high-risk group of school children in Bangalore City. The study was conducted in two schools, randomly selected from a list of schools catering to underprivileged children. These schools were randomly allocated into experimental and control groups. Children aged 9-16 years having three or more incipient or cavitated primary or secondary carious lesions were enrolled in the study. In the experimental group, APF gel was applied and oral health education was provided to both groups at baseline and 6 months. Follow-up examination was performed at 6 and 12 months and the caries status was recorded by an investigator who was blinded to the allocation of intervention. There was no statistically significant difference in DMFT and DMFS values, but a significant difference was seen in incipient carious lesions between the experimental and control groups at 6 and 12 months. These results suggest that biannual APF gel application is an effective preventive measure in reversing incipient carious lesions.

APF and dentifrice effect on root dentin demineralization and biofilm.

Because dentin is more caries-susceptible than enamel, its demineralization may be more influenced by additional fluoride (F). We hypothesized that a combination of professional F, applied as acidulated phosphate F (APF), and use of 1100-ppm-F dentifrice would provide additional protection for dentin compared with 1100-ppm-F alone. Twelve adult volunteers wore palatal appliances containing root dentin slabs, which were subjected, during 4 experimental phases of 7 days each, to biofilm accumulation and sucrose exposure 8x/day. The volunteers were randomly assigned to the following treatments: placebo dentifrice (PD), 1100-ppm-F dentifrice (FD), APF + PD, and APF+FD. APF gel (1.23% F) was applied to the slabs once at the beginning of the experimental phase, and the dentifrices were used 3x/day. APF and FD increased F concentration in biofilm fluid and reduced root dentin demineralization, presenting an additive effect. Analysis of the data suggests that the combination of APF gel application and daily regular use of 1100-ppm-F dentifrice may provide additional protection against root caries compared with the dentifrice alone.

Effect of rinsing with water immediately after neutral gel and foam fluoride topical application on enamel remineralization: An in situ study.

OBJECTIVE: The aim of this study was to evaluate, in situ, the effect of rinsing with water immediately after neutral fluoride foam application (Foam) or fluoride gel application (Gel). DESIGN: Ten volunteers wore acrylic palatal appliances containing 4 enamel blocks selected by surface hardness with artificial caries. Five experimental regimes of 3 days each were set according to treatment: placebo; Gel and Foam followed by no rinsing or consuming of liquids or solids for the next 30min; Gel and Foam followed by immediately washing with water jet. After each phase, surface hardness was again measured for analysis of mineral gain, evaluated through percentage of surface hardness recovery (%SHR) and integrated loss of subsurface hardness (ΔKHN). The concentration of loosely bound fluoride (CaF2) and firmly bound fluoride (FA-like) formed and retained were also determined. RESULTS: Fluoride treatments produced greater remineralization (%SHR and ΔKHN) compared to placebo group (p<0.05). There was no difference in the ability to promote remineralization and in the concentration of fluoride formed and retained, in each analysis, between Gel and Foam (p>0.05). CONCLUSION: The data suggest that rinsing with water immediately after topical application does not seem to have an influence on the ability of fluoride to promote remineralization.

Effect of fluoride varnish and gel on dental erosion in primary and permanent teeth.

OBJECTIVE: To assess the effect of a fluoride varnish and gel on the erosive wear of primary and permanent teeth. DESIGN: Sixty human primary (n=30) and permanent (n=30) enamel specimens were randomly assigned to one of the following groups: APF gel (1.23% F), NaF varnish (2.26% F), and control (no treatment). Fluoride gel was applied for 4 min and fluoride varnish for 24 h. Six daily demineralisation-remineralization cycles of 5 min of immersion in a cola drink (pH 2.3) and 30 min in artificial saliva were conducted during 7 days. All specimens were stored in artificial saliva between and after cycles. Surface Knoop microhardness (%SMHC) readings were performed at baseline, 48 h and 7 days. Data were tested using ANOVA and Tukey's tests (p<0.05). RESULTS: For primary enamel, the mean %SMHC (+/-SD) after 48 h and 7 days was, respectively: gel (31.0+/-14.4 and 36.9+/-7.5), varnish (26.7+/-9.5 and 38.3+/-8.7), and control (35.8+/-8.6 and 45.0+/-8.6). For permanent enamel, such values were: gel (37.5+/-7.7 and 27.8+/-7.5), varnish (31.7+/-9.6 and 27.4+/-11.1) and control (48.6+/-6.4 and 43.1+/-6.4). In primary enamel, erosion inhibition by fluoride was not significant at 48 h (p=0.203) and 7 days (p=0.082). In permanent specimens, both products showed a significant effect (p<0.001). CONCLUSIONS: Both fluoride varnish and gel were able to inhibit erosive enamel loss but mainly in the permanent experimental groups. Primary and permanent enamel substrates reacted differently to both demineralization by a cola drink and remineralization by fluoridated compounds.