Acidulated Phosphate Fluoride Gel Research Articles

Influence of fluoride characteristics on tooth surface protection in an erosive condition: A multifaceted characterization approach.

To evaluate the effect of fluoride consistency and composition to protect enamel and dentin against the dental erosion. Bovine enamel and dentin specimens were treated with artificial saliva, neutral fluoride gel (NFG), acidulated phosphate fluoride gel (AFG), neutral fluoride foam (NFF), and acidulated phosphate fluoride foam. The samples were subjected to cycling. Micro energy-dispersive X-ray fluorescence spectrometry, surface roughness (Ra), contact angle (CA), and scanning electron microscopy (SEM) were performed. Composition, CA and Ra data were analyzed by ANOVA and multiple comparison test (p < 0.05). The dentin protected had a significantly higher mineral content than in the control. Eroded unprotected enamel had higher Ra values than normal surfaces. Fluoride treatments increased the Ra in dentin samples. AFG increased the CA in enamel. Fluoride foams increased CA in dentin with reduced mineral loss. SEM analysis found a deposited layer on enamel treated with AFG and remnants of deposits on dentin treated with NFG and NFF. Regardless of the form of application, fluoride provided protection against erosion, however with different levels. Applying the adequate fluoride form is relevant since the formulations have different effects on both enamel and dentin.

CO2 laser irradiation combined with fluoridated dentifrice improved its protective effect on caries lesion progression regardless of the acidulated phosphate fluoride gel application: An in situ study.

This in situ study aimed to investigate the efficacy of CO2 laser at a 10.6-µm wavelength combined with 1.23% acidulated phosphate fluoride (APF) and fluoridated dentifrice with 1100µg F/g (FD) to control enamel caries progression. Sixteen volunteers wore palatal appliances containing eight demineralized enamel specimens for four 14-day phases under sucrose exposure. These specimens were submitted to CO2 laser irradiation and APF alone or combined with FD. Treatment groups were non-fluoridated dentifrice-NFD, NFD + CO2 laser, NFD + APF, NFD + CO2 laser + APF, FD, FD + CO2 laser, FD + APF, and FD + CO2 laser + APF. Mineral loss, calcium fluoride (CaF2), fluorapatite (FAp), and fluoride in the biofilm were analyzed by analysis of variance followed by the Student-Newman-Keuls test, p < 0.05. The highest mineral loss inhibition was noted when FD and CO2 laser irradiation were combined, which did not significantly differ from the FD + CO2 laser + APF group. The CaF2, FAp, and F in the biofilm were more pronounced when the FD and APF were combined. The CO2 laser irradiation promoted a slightly higher concentration of CaF2 in the enamel and F in the biofilm. Although APF promotes the high formation of CaF2 and FAp, the combined use of FD with CO2 laser overcomes the APF effect in inhibiting the progression of artificial caries-like lesions in situ. Under the in situ design of this study, remineralization of white spot lesions was achieved through CO2 laser irradiation and daily use of fluoridated dentifrice. Future clinical trials are encouraged to substantiate this finding.

Effectiveness of MI Varnish™ and PreviDent® Varnish in Noncavitated Interproximal Lesions: A Randomized Clinical Trial.

Evaluating the remineralization efficacy of noncavitated proximal incipient lesions with Colgate® PreviDent® and MI™ varnishes in comparison to the industry standard (1.23%) acidulated phosphate fluoride (APF) gel. Parallel randomized controlled, multicenter, single-blinded trial. By flipping a coin, 18 patients with 91 lesions were divided into three groups. The Colgate® PreviDent (n = 33), MI varnish (n = 30), and control (APF gel) groups (n = 28) were identified as the three arms. We conducted an initial assessment and therapy as well as follow-ups at 3 and 6 months to evaluate the course of the caries lesion. Caries progression was significantly reduced on treated surfaces across both groups. Nine surfaces in the Colgate® PreviDent® group with white spots and dryness did not change, one surface turned into a white patch without dryness, and another surface changed to a sound surface; only two surfaces were discontinued from treatment (restored) due to a misdiagnosis by the operator (n = 2). Nine of the surfaces in the MI™ group maintained their white patches with dryness, whereas one developed a new white patch that was not dry. Only MI varnish™-treated teeth exhibited dramatic radiographic improvement. Caries on the outside enamel were either unchanged or restored to healthy levels. Caries on the inner surface of the enamel also did not change. Remineralizing noncavitated early-stage lesions may be done with both MI™ and Colgate® PreviDent® varnishes. Despite this, radiographic results did not vary significantly across the three groups. In situations of rather advanced incipient caries seen on radiographs, the MI varnish™ might be recommended. Helal N, Azzahrani GS, Azzouz LZ. Effectiveness of MI VarnishTM and PreviDent® Varnish in Noncavitated Interproximal Lesions: A Randomized Clinical Trial. Int J Clin Pediatr Dent 2023;16(5):751-757.

In Vitro Effect Of Fluoride Prophylactic Agents On Titanium Molybdenum Alloy And Stainless Steel Orthodontic Wires – Scanning Electron Microscope Study

Background: TMA (Titanium-molybdenum) and SS (Stainless steel) wires are most commonly availed for orthodontic treatment. Meanwhile, patients are encouraged to employ mouthwashes containing fluoride to maintain their oral hygiene. Objective: To assess the effect of different fluoride prophylactic agents on TMA and SS wires for specific time periods namely 10 minutes, 1 hour, 24 hours. Material and Methods: The sample comprised TMA and SS wires immersed in agents such as Artificial saliva (pH = 6.8), Acidulated phosphate fluoride gel 1.23% and Stannous fluoride 0.4% to evaluate surface changes incorporated. 180 cut wires were used in this study; out of which half were SS and the other half were TMA wires. These wires were immersed for 10 minutes, 1 hour and 24 hours in each agent. Scanning electron microscope was also utilized to analyze the surface alterations. Results: The roughness of these wires increased after immersing in prophylactic agents. An increase in the surface roughness was found with SS wires in stannous fluoridesolution and APF gel on immersion at 10 minutes, 1 hour, and 24 hours’ time intervals with p-value being significant at 24 hour time in stannous fluoride. Conclusion: Orthodontists must avoid the contact of orthodontic wires containing titanium protective coating with prophylactic agents. Bangladesh Journal of Medical Science Vol.22 (Special Issue) 2023 p.47-51

Preventive effect of combined Er, Cr: YSGG and fluoride gel on acid resistance of the permanent tooth enamel: An in vitro study.

Increasing the resistance of enamel to acids may prevent dental erosion and diminish microhardness alterations in the enamel. This study aimed to evaluate the preventive effect of erbium, chromium: yttrium, scandium, gallium, and garnet laser combined with 1.23% acidulated phosphate fluoride gel on enamel resistance to demineralization. Thirty-four human maxillary first premolars were randomly assigned to three groups. Group I (control group), group II were treated with fluoride gel for 4-minutes and group III received ten seconds of laser treatment; then fluoride has applied. Each sample was immersed in a soft drink for 2 minutes, then washed and kept in deionized water. Four consecutive cycles were carried out at 6 hours intervals. The effects were studied utilizing the Vickers microhardness test and scanning electron microscopy. Data analyses were performed by Levene test and General Linear Model Repeated Measure Factorial ANOVA with Bonferonni post hoc test, the accepted level of significance was 0.05. Microhardness was increased statistically in groups II and III after treatment, with the highest value for group III. After demineralization, the control group had the lowest microhardness score, followed by group II and group III, which showed the least reduction in microhardness with a statistical significance (p<0.05). There was a correlation between the morphological alterations in enamel surfaces and the increased enamel resistance. Both fluoride and the combined laser fluoride treatment had an advantage in protecting the enamel and increasing enamel resistance to acids, with a more significant benefit for the combined laser fluoride group. Key words:Prevention, Er, Cr: YSGG, enamel demineralization, fluoride, microhardness.

Comparative Evaluation of Antimicrobial Efficacy of Fluoride-Based and Self-Assembling Peptide P11-4-based Tooth Remineralization Agents on Streptococcus mutans: A Microbiological Study.

Dental caries is a biofilm-related oral disease that continues to afflict the majority of the world's population. The disease results from an interaction between specific bacteria and dietary constituents within a biofilm known as dental plaque. Among the cariogenic microorganisms, Streptococcus mutans (S. mutans) plays pivotal role in caries-inducing processes. Evaluate and compare the antimicrobial efficacy of self-assembling peptide P11-4-based tooth remineralization agents on S. mutans. An in vitro microbiological study. The antibacterial efficacy of self-assembling peptide P11-4 gel (Group 1), fluoride enhanced hydroxyapatite gel (Group 2), acidulated phosphate fluoride gel (Group 3), chlorhexidine gluconate gel 1.0% w/w (Group 4; positive control), and normal saline (Group 5; negative control) was performed using time-kill assay over a period of 24 h and the number of S. mutans colony-forming units (CFUs) were calculated. Statistical analysis was done using Kruskal-Wallis test and Mann-Whitney post hoc Test. The level of significance was set at P < 0.05. Group 1 showed mean CFUs (× 103) of 841.33 ± 3.51, Group 2 showed 10035.33 ± 60.68, Group 3 showed 1058.00 ± 56.96, Group 4 showed 0.00 ± 0.00, and Group 5 showed mean CFUs with 15226.67 ± 96.67. The difference in the mean CFUs (× 103) between different groups was statistically significant at P < 0.001. The self-assembling peptide P11-4-based tooth remineralization agent exhibited an inhibitory influence on S. mutans and hence formation of cariogenic bacteria dominant biofilm can thus be affected by its application.

Is professionally applied fluoride effective in preventing or arresting caries in older adults?

Design Systematic review of clinical trials.Case selection Clinical trials with adults 60 years of age or older who professionally received fluoride therapy for caries prevention or arrest. Controls were adults of the same age group who received another professionally applied fluoride agent, placebo, or nothing.Data analysis The expected outcomes were the mean difference in the number of new caries, caries prevented fraction and caries arrest rate. Independently, two researchers assessed the risk of bias in the included studies.Results Seven studies met the selection criteria where 5% sodium fluoride varnish, 38% sodium diamine fluoride solution and 1.23% acidulated phosphate fluoride gel were used with root caries and coronal caries. Given the nature of the studies, the three agents were effective in preventing root caries in older adults. None of the agents were particularly superior to the others.Conclusions Professionally applied fluoride is effective in preventing dental caries in older adults.

Estimation of wettability of topical fluoride gel on anterior and posterior teeth: An in vitro study.

The surface area determination has a vital role in measuring the properties of liquid and solid substances. Fluoride is a potent remineralizing agent of the teeth. The surface area is measured using a goniometer. The main aim of this study is to estimate the wettability of topical fluoride gel on the anterior and posterior teeth surfaces. Topical acidulated phosphate fluoride (APF) gel was taken in small quantities. Anterior and posterior teeth were collected, and their superficial unaltered enamel sections were used as the surface where the contact angle (CA) is determined. The surface wettability is determined using Ossila goniometer to measure CA. Each stage was mounted on a mechanical stage of the goniometer. A calibrated microsyringe was used to dispense drops of the APF gel over the surface of the specimen Group A (anterior tooth cut section) and Group B (posterior tooth cut section). This procedure is repeated for all specimen samples. The mean of CAs of the anterior teeth (88.41°) was greater when compared with the mean of posterior teeth (80.36°) CA. P value found using the paired t-test of SPSS software is found to be 0.271 (>0.05), hence statistically not significant. The greater the CA, the lower is the degree of wettability on the teeth surfaces. The mean CA of the topical fluoride APF gel on the anterior tooth surface is greater when compared to the posterior tooth surface. This signifies that greater wettability is seen on posterior tooth surfaces.

&lt;strong&gt;The effect of acidulated phosphate fluoride (APF) gel against erosion on enamel microstructure of primary teeth which soaked with Citrus aurantifolia &lt;/strong&gt;

ABSTRACTIntroduction: Erosion is a common dental problem that is especially prevalent in children due to the increasing consumption of acidic food and beverages. APF gel is believed to be effective in reducing the demineralization effect of the teeth as well as escalating the remineralization process. This research aims to determine and evaluate the effectiveness of 1.23% APF gel as a preventive agent for the erosion of tooth enamel, specifically in deciduous teeth. Methods: This type of research is true experimental research. The population of this research would be primary teeth extracted from children, using a purposive sampling technique with inclusive and exclusive criteria. A total amount of 5 maxillary primary central incisors were extracted and cleaned. APF gel was applied repetitively on the left side of the teeth for 4 minutes every hour, whereas the right side was left as it is. Samples were then analyzed using a scanning electron microscope (SEM). A qualitative and subjective analysis regarding the micromorphological features of the erosion can be done. Result: The side of teeth without APF gel application has a greater erosion rate compared with teeth with APF gel application. The tooth which is demineralized shows a honeycomb structure of the interprismatic enamel. As for the dentinal tubules, teeth without APF gel application have a bigger opening of dentinal tubules, going up to 7.868 micrometers in size compared to teeth with APF gel application (1-2 micrometers). Conclusion: The application of professional acidulated phosphate fluoride (APF) gel on deciduous teeth even when soaked in Citrus aurantifolia, is proven to be effective in preventing dental erosion.Keywords: acidulated phosphate fluoride (APF) gel; citrus aurantifolia; dental erosion; primary tooth

Gels containing statherin-derived peptide protect against enamel and dentin erosive tooth wear in vitro

The effect of gels containing a statherin-derived peptide (Stn) on the protection against enamel and dentin erosive tooth wear (ETW) in vitro was evaluated. Bovine enamel and dentin specimens were divided into 2 groups (n = 15 and 18/group for enamel and dentin, respectively) that were treated with Chitosan or Carboxymethylcellulose (CMC) gels containing Stn15pSpS at 1.88 × 10-5 M or 3.76 × 10-5 M. Chitosan or CMC gels without active ingredients served as negative controls, while chitosan gel containing 1.23% F (as NaF) and acidulated phosphate fluoride gel (1.23% F) served as positive controls. The gels were applied on the specimens for 4 min. Stimulated saliva was collected from 3 donors and used to form a 2-h acquired pellicle on the specimens. Then, the specimens were submitted to an erosive pH cycling protocol 4 times/day for 7 days (0.01 M HCl pH 2.0/45 s, artificial saliva/2 h, and artificial saliva overnight). The gels were applied again during pH cycling, 2 times/day for 4 min after the first and last erosive challenges. Enamel and dentin loss (μm) were assessed by contact profilometry. Scanning electron microscopy (SEM) was analyzed using a cold field emission. Data were analyzed by two-way ANOVA (for chitosan and CMC gels, separately) and Tukey's multiple comparison test. SEM images showed changes to enamel topography after application oft the gels containing Stn or F. Regarding CMC-based gels, for enamel, none of the treatments significantly reduced ETW in comparison with placebo; for dentin, however, gels containing Stn, regardless the concentration, significantly reduced the ETW. Moreover, Chitosan-based gels, regardless the Stn concentration, were able to protect enamel and dentin against ETW. Gels containing Stn might be a new approach to protect against ETW.

Development of a sodium fluoride and stannous chloride-containing gel for treatment of dental erosion

This study synthesized and tested experimental gels containing fluoride (F-) and stannous (Sn2+) ions for the control of dental erosion. Enamel and dentin polished specimens were eroded (1% citric acid solution, 10 min) and randomly allocated into 5 groups (n=10): Placebo - Hydroxypropyl Methylcellulose (HMC) gel; F+Sn+HMC - 7,500 ppm F- / 15,000 ppm Sn2+; F+HMC - 7,500 ppm F-; Commercial acidulated phosphate fluoride gel (12,300 ppm F-); and Control - no treatment. After treatment (applied for 60 s), specimens underwent an erosion-remineralization cycling (5 min in 0.3% citric acid solution, 60 min in artificial saliva, 4×/day, 20 days). Surface loss (SL, in µm) was determined after the 5th, 10th and 20th days of cycling (α=0.05). For enamel, after 5 and 10 days, F+Sn+HMC presented the lowest SL, which did not differ from the commercial gel. After 20 days, no differences were found between commercial, F+HMC, and F+Sn+HMC groups. Placebo did not differ from the control at any time points, and both groups presented the highest SL when compared to the other groups. For dentin, on the 5th day, F+Sn+HMC, F+HMC and commercial did not differ significantly, showing lower SL than the control and the placebo. On the 10th day, F+Sn+HMC and commercial presented the lowest SL compared to control and placebo. After 20 days, only the commercial gel showed lower SL than the control and placebo. Thus, the experimental F+Sn+HMC gel was able to control the progression of tooth erosion.

Influence of the Type of Topical Fluoride Delivery at Various Restoration Time Points on the Micro-Shear Bond Strength of a Resin-Based Composite on Bleached Tooth Enamel.

BackgroundThis study aimed to evaluate the micro-shear bond strength (mSBS) of an adhesive applied to bleached enamel to determine the effects of fluoride supply and restoration time on the mSBS.MethodologyIn this study, we bleached 130 samples of enamel and split them into the following three groups of 40 each: group MI: McInnes bleaching solution; group MIF: McInnes bleaching solution + topical acidulated phosphate fluoride gel; group FMI: 2% fluoridated McInnes bleaching solution. Non-bleaching or fluoridation was performed on a group of 10. Subgroups were created for each group (except for the control) to be restored for seven, 14, or 21 days. The mSBS test was performed on a universal testing machine after Tygon tubes were filled with composite resin and put on enamel surfaces. Tukey’s post-hoc test (p = 0.05) and two-way analysis of variance were employed to analyze the data.ResultsThe mSBS values obtained for all groups immediately and after seven days were lower, while at 14 and 21 days were similar to the control group. According to the data, group FMI had greater mSBS levels than groups MI and MIF, both immediately and seven days later.ConclusionsWhen in-office bleaching was employed, only the fluoride McInnes solution was successful in quickly correcting the adverse effects of low mSBS.

Caries inhibition of simulated active caries lesions with CO2 laser irradiation and fluoride.

It has been well established that CO2 laser irradiation can be used to transform the mineral phase of dental enamel to make it more resistant to acid dissolution. The purpose of this study was to investigate if carbon dioxide laser irradiation and topical fluoride can be used to treat incipient caries lesions to inhibit further progression, i.e. treat active lesion surfaces as opposed to sound surfaces prior to subjecting them to an acid challenge. Simulated active caries lesions were produced on twenty eight bovine enamel samples using a pH cycling model and those surfaces were irradiated by a 9.4 μm CO2 laser and treated with topical fluoride. Changes in the surface morphology, acid resistance, and permeability were measured using digital microscopy, optical coherence tomography (OCT), and SWIR reflectance surface dehydration rate measurements at 1950 nm after exposure to a further acid challenge. There was a significant reduction (P < 0.05) of further lesion progression for lesion windows treated with CO2 laser irradiation followed by the application of an acidulated phosphate fluoride gel compared to the untreated lesion windows on each sample. Treatment by laser irradiation alone was not effective. The degree of lesion inhibition was not as high as has been previously observed for laser irradiated sound enamel surfaces exposed to an acid challenge.

Effectiveness of Nanoparticle-Based Acidulated Phosphate Fluoride (APF) Gel on Surface Enamel Fluoride Uptake: an Interventional Study.

Statement of the Problem: Despite topical fluoride being used for over 50 years in caries prevention, its complete potential in terms of formation of fluorapatite enamel and prolonged surface retention has not been harnessed.Purpose: This study aimed to assess the effectiveness of nanoparticle based acidulated phosphate fluoride (APF) gel on surface enamel fluoride uptake through split mouth design over a period of six months, on patients undergoing orthodontic treatment and indicated for bilateral extraction of premolars on at least one of the arch.Materials and Method: A split mouth non randomized clinical trial was performed. Each of the 30 participants received one application of 4 minutes duration of both the intervention: Right half of the mouth received nanoparticle based APF gel, and left half of the mouth received conventional APF gel (16 Oz Pascal Corp.; strawberry flavor). Bilateral acid etch biopsy of enamel surface was take at 3 intervals- baseline,24 hours and 30 days. Using 1ml of 0.5M perchloric acid, acid etch enamel biopsy was taken for all the study subjects at 3 intervals of time (baseline, 24 hours and 30 days), bilaterally on the buccal and palatal/lingual surface of maxillary or mandibular premolars indicated for extraction, using 1 (l of 0.5M perchloric acid. After the premolars were extracted, scanning electron microscope (SEM) analysis was done to determine the surface characteristics of enamel in both groups.Results: Overall, both fluoride uptake and depth of biopsy remained significant even after controlling for the covariates (time, group) individually and simultaneously (p< 0.05). Further analysis showed that fluoride uptake was significantly increased and biopsy depth significantly decreased in the nanoparticle based APF gel group at 24 hour and 30 day evaluation respectively.Conclusion: By reducing the size of sodium fluoride to increase the surface enamel uptake, our results support the use of this top down approach as a promising strategy for effective delivery of topical fluorides. This highlights that the top down approach of nanoscience to reduce the size active compound sodium fluoride has increased the uptake and retention of surface enamel fluoride.

Fluoride Formed on Enamel by Fluoride Varnish or Gel Application: A Randomized Controlled Clinical Trial

Although fluoride varnish (FV) and acidulated phosphate fluoride gel (APF-gel) are considered clinically effective to reduce caries, in vitro studies have shown that FV reacts slowly with enamel because most NaF present in the formulation is not solubilized in the FV. Therefore, we conducted a clinical study to evaluate if the time that FV remains on dental surfaces could overcome its slower chemical reactivity when compared with APF-gel. Sixty-eight volunteers were randomly allocated into 4 groups: negative control (Control, no treatment), APF-gel application (1.23% F applied for 4 min), and FV application (Duraphat®, 2.26% F) for 4 h (FV-4h) or 24 h (FV-24 h). To evaluate fluoride formed and retained on enamel, acid biopsies were made on the buccal surfaces of the maxillary central incisors before, at the end of the application of fluoride products (immediately after gel application, or after 4 or 24 h of varnish application), and after 7 and 28 days. Fluoride concentration in dental biofilm was also analyzed before and up to 28 days after initial application. The data were analyzed by 2-way ANOVA, considering treatment and time as factors. The APF-gel and FV-24h groups formed greater fluoride concentration on enamel than the FV-4h and the control group at the end of application (p = 0.0001), with no difference from each other (p = 0.99). The groups did not differ regarding fluoride in biofilm fluid (p = 0.73) and solids (p = 0.40). In conclusion, FV needs to remain in contact with the teeth for prolonged times (>4 h) to reach the same reactivity obtained by a 4-min application of APF-gel.

Biomineralization induced by chitosan and collagen-based materials with fluoride for dentin coverage: Chemical and morphological analysis.

The prevention and treatment of erosive tooth wear are becoming increasingly important due to its increasing prevalence. The use of natural solutions to modify dental surfaces has become an area of research. Organic materials such as chitosan and hydrolyzed collagen may be a promising option to treat dentin. This in vitro study aimed to evaluate the influence of chitosan or hydrolyzed collagen, alone or combined with acidulated phosphate fluoride (APF) gel, on the composition and morphology of dentin after erosion. Bovine dentin samples were prepared (n= 84) and treated with artificial saliva (AS, negative control); APF gel (F, positive control); chitosan solution (Chi); hydrolyzed collagen solution (Col); fluoride/chitosan composition (F_Chi); and fluoride/hydrolyzed collagen composition (F_Col). Erosive cycles (six cycles of immersion in orange juice for 1min, followed by immersion in AS for 1 hr) were performed. The materials were characterized by their morphology, composition, and particle size distribution. Micro-energy dispersive X-ray fluorescence spectroscopy and scanning electron were used to evaluate the dentin's inorganic chemical composition and morphology. The F_Col and F groups had a reduction in calcium loss by 17 and 26%, respectively (p<.001). Both of these groups still had a covering layer of agglomerates at the dentin surface after the erosive cycles. The fluoridated chitosan or collagen solutions improved the dentin resistance to erosion as a novel hybrid-fluoride-based material approach to provide surface protection from erosion.

Effect of Er:YAG Laser Irradiation and Acidulated Phosphate Fluoride Therapy on Re-Mineralization of White Spot Lesions.

Statement of the Problem: Studies on the efficacy of erbium laser for enhancement of enamel resistance to acid attacks and its effects on fluoride uptake by the enamel are limited.Purpose: This study sought to assess and compare the effects of erbium-doped yttrium aluminum garnet (Er:YAG) laser irradiation and application of acidulated phosphate fluoride (APF) gel (alone and in combination) on remineralization of artificial white spot lesions (WSLs).Materials and Method: This in vitro, experimental study evaluated 90 buccal and lingual slabs of extracted human premolars. The specimens underwent pH cycling to induce WSLs. They were then randomly divided into 6 groups of caries-free positive control (c+), negative control with WSLs (ws), 1.23% APF gel applied on the enamel (F), Er:YAG laser irradiation (80 mJ, 10 Hz, and 8 J/cm2) of enamel (L), APF gel application followed by laser irradiation (FL), and laser irradiation followed by fluoride gel application (LF). The fluoride ion content of specimens was measured before and after the intervention using a potentiometer. Data were analyzed by ANOVA (p< 0.05).Results: APF gel application before/after laser irradiation maximally increased the fluoride uptake by the enamel (p= 0.000). Application of APF gel in group F and laser irradiation in group L increased fluoride uptake by the enamel, compared with groups 1 and 2 (p= 0.000). Laser- treated (L) and APF-treated (F) groups had no significant difference in this respect (p= 0.945). Maximum fluoride concentration was noted in combined laser and fluoride groups (FL=332.07ppm and LF=341.27ppm) with no significant difference between the two (p= 1.000).Conclusion: Er:YAG laser irradiation changes the chemical composition of enamel and probably promote its remineralization, especially when combined with APF gel application, which highlights its cariostatic potential.

Cytotoxicity, genotoxicity, and cellular metal accumulation caused by professionally applied fluoride products in patients with fixed orthodontic appliances: A randomized clinical trial

Corrosion of metal orthodontic appliances caused by professional fluoride products has been recently concerned. Therefore, the objective of this study was to evaluate the cytotoxic and genotoxic effect of these products on buccal mucosal cells from patients wearing fixed orthodontic appliances. A total of 44 patients, aged 12 to 35 years, who began orthodontic treatment with fixed appliances were included in this single-center, prospective, randomized clinical trial. Patients were randomly allocated into 4 parallel groups according to the type of professional fluoride treatment applied after placing the appliances: acidulated phosphate fluoride gel (APF); neutral fluoride gel (NGel); fluoride varnish (FVa); and without fluoride treatment (control). Buccal cells were collected before treatment (T1) and 3 months after appliance placement (T2). The cells were assayed for cell viability and underwent Papanicolaou staining. Cells with micronuclei and degenerative nuclear alterations were scored using a light microscope. Cell metal content was quantified by inductively coupled plasma-mass spectrometry. The data were analyzed with the Kruskal-Wallis test. The intracellular nickel content in the APF group significantly increased (P < 0.05), whereas that of the control, NGel, and FVa groups did not. The changes in chromium concentration in all groups were not significantly different compared with control. Use of APF resulted in a significantly higher decrease in cell viability and increase in morphologic signs of cell death compared with control (P < 0.05). The change in frequency of micronucleated cells was not significantly different from that in the control group. Applying APF gel on fixed orthodontic appliances increased the cell metal content and decreased cell viability; however, genotoxic effects were absent. FVa and NGel are suggested as the products of choice to use during orthodontic treatment.

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

ObjectiveThis 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.Methods120 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%).ResultsThe 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.ConclusionNd: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.

Exposure to the oral environment enhances the corrosion of metal orthodontic appliances caused by fluoride-containing products: Cytotoxicity, metal ion release, and surface roughness

This study aimed to evaluate the metal ion release, cytotoxicity, and surface roughness of clinically used metal orthodontic appliances after immersion in different fluoride product solutions compared with those of new appliances. Used fixed appliances were debonded from 36 patients after their treatment was done. New appliances were as-received. Each used and new group comprised 36 sets of 20 brackets and 4 tubes that were divided into 3 groups by archwire type; stainless steel, nickel-titanium, and beta-titanium. The samples in each group were divided into 3 subgroups and immersed in solutions of fluoride toothpaste, 1.23% acidulated phosphate fluoride, or artificial saliva without fluoride as a control group. The immersion times were estimated from the recommended time for using each fluoride product for 3months. The samples were then immersed in Dulbecco's Modified Eagle's Medium for 7days. The cytotoxicity test was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay using primary gingival fibroblasts. Chromium, nickel, and iron ion release were detected using inductively coupled plasma mass spectroscopy. The surface roughness of the brackets and wires was measured by a scanning electron microscope and a noncontact optical 3-dimensional surface characterization and roughness measuring device. The data were analyzed using the paired t test and 2-way analysis of variance. Used brackets demonstrated a significantly higher ion release, surface roughness, and cytotoxicity than the new brackets. Acidulated phosphate fluoride significantly increased the ion release and surface roughness; however, it significantly decreased cell viability, especially in the titanium molybdenum subgroup. Used brackets were significantly prone to further corrosion. Acidulated phosphate fluoride gel should not be used in orthodontic patients with fixed metal appliances.