Physical properties and enamel remineralization potential of arginine-fluoride varnishes.

OBJECTIVE: The study objectives were to examine the physical properties and enamel remineralization potential of fluoride (F) varnishes incorporated with arginine (Arg). METHODS: Four commercial F varnishes: 1) Duraphat®; 2) Flúor Protector®, 3) Fluor Protector S®, and 4) Fluorimax™ were supplemented with 2% w/v. Arg. The control/experimental varnishes underwent rheometric analysis to assess varnish density (δ), velocity (ν), and associated viscosity, both quantitatively (ν/δ) and qualitatively based on determined mass, volume, distance flow, and time under experimentation. The varnish wet/dry weights (at 2 h) were also analysed. Further, sound enamel specimens (T0) with artificial incipient caries-like lesions (T1) were treated with control/experimental varnishes and subjected to remineralization assay with artificial saliva for 6 h. Thereafter (T2), the specimens were characterized to estimate precipitated Ca and net enamel F uptake. Additionally, mineral density (MD) was assessed using micro-CT at T0, T1, and T2 to derive mineral gain (MG) and % remineralization for the treatment groups. RESULTS: When Arg is incorporated, the physical properties of the F-containing varnishes undergo a significant transformation, resulting in higher density, varnish weight, dry varnish weight, and viscosity compared to their respective control varnishes (p < 0.05). Incorporating Arg-in Duraphat®, Fluor Protector S®, and Fluorimax™ significantly improved both enamel Ca precipitation and F uptake compared to the respective controls (p < 0.05). Additionally, the enamel F uptake was significantly higher with all the tested varnishes when enriched with Arg (p < 0.05). The combined data for MD, MG, and % remineralization suggests that the remineralization potential of F-varnishes significantly increased when enriched with Arg (p < 0.05). CONCLUSION: Incorporating Arg in inorganic F varnishes improves their physical properties and enhances the enamel remineralization potential of the varnishes. CLINICAL SIGNIFICANCE: This study highlights the possibility of incorporating Arg in distinct F-source varnishes. The synergism between active components (Arg-F) aids in enhanced remineralization and superior varnish physical properties, demonstrating a promising approach for high caries-risk patients.

High-Resolution Characterization of Enamel Remineralization Using Time-of-Flight Secondary Ion Mass Spectrometry and Electron Microscopy.

INTRODUCTION: The aim of this in vitro study was to assess the suitability of high-resolution time-of-flight secondary ion mass spectrometry (ToF-SIMS) for visualizing cross-sectional changes in human enamel microstructure and chemical composition during treatment and remineralization cycling of artificially generated caries lesions underneath an artificial plaque. METHODS: Treatments consisted of exposure to twice daily toothpaste/water slurries prepared from 0, 1,100, and 5,000 µg/g fluoride (F) NaF/silica toothpastes. In addition, treatments with slurries prepared from 1,100 µg/g F SnF2/silica toothpastes were done using 44Ca in the remineralization solution to allow for differentiation of newly formed mineral and exploration of incorporated metal dopants using ToF-SIMS. Complementary microhardness, scanning electron microscopy, and high-resolution transmission electron microscopy (HR-TEM) investigations were performed on enamel cross sections. RESULTS: HR-TEM was used for the first time to determine the change in crystallinity during remineralization revealing distinct microstructural zones within one lesion. Chemical mapping using ToF-SIMS demonstrated that the distribution of F, while observed primarily in the new mineral phase, was widespread throughout the lesion with 44Ca substantially limited to the remineralizing mineral. Both penetrated the inter-rod spaces of the sound enamel illustrating how acid damage propagates into the native mineral as the caries lesion deepens. HR-TEM examination revealed different regions within the lesion characterized by distinct micro- and ultrastructures. Importantly, HR-TEM revealed a return of crystallinity following remineralization. F dose-response observations verified the ability of these high-resolution techniques to differentiate remineralization efficacy. CONCLUSION: The collective results provided new insights such as the visualization of F or calcium penetration pathways, as well as new tools to study the caries process.

Effects of Propolis-Based Herbal Toothpaste on Dentine Hypersensitivity.

INTRODUCTION: The objective of this in vitro study was to compare the effectiveness of a propolis-based herbal toothpaste with 5% sodium fluoride varnishin obstructing human dentinal tubules; Scanning electron microscopy was utilised to obtain quantitative and qulitative data on tubular obstruction. METHODS: Thirty-nine extracted human premolar teeth were collected. The cementum layer was removed using a water-cooled diamond bur and the smear layer using ethylenediaminetetraacetic acid (EDTA) 17%. Then, the samples were randomly divided into 3 groups (n = 13 each), as follows: group 1: dentin discs exposed to the propolis-based herbal toothpaste (Herbex); group 2: dentin discs exposed to 5% sodium fluoride varnish; and group 3: control. Then, all discs were observed and imaged in 4 non-overlapping fields by an electron microscope at 2000× magnification. The topography and number of open, closed, and semi-closed tubules were counted in all images. The data were analysed using Kruskal-Wallis test, Mann-Whitney U test, and Friedman test. The statistical analysis was performed with SPSS statistic 22.0 software, with a significance level of α = 0.05. RESULTS: In pairwise comparisons of the groups considering the percentage of open, closed, and semi-closed tubules, the difference was not statistically significant between the 5% sodium fluoride varnish and propolis groups in the closed and semi-closed tubules, but it was statistically significant with the control group. Additionally, the percentage of open tubules in the propolis-based herbal toothpaste group was significantly lower than in the 5% sodium fluoride varnish and control group. CONCLUSIONS: Both propolis-based herbal toothpaste and 5% sodium fluoride varnish is effective in blocking human dentin tubules to various extents.

The effect of different concentrations of fluoride in toothpastes with or without bioactive glass on artificial root caries.

OBJECTIVE: To investigate the effect of different toothpastes either containing 5,000ppm-F, 1,450ppm-F or bioactive glass (BG) with 540ppm-F on artificial root carious lesions (ARCLs). METHOD: The crowns of 23 extracted sound teeth were removed leaving their roots only. Subsequently, each root was divided into four parts. A total of 15 sound root dentine (SRD) was left untreated as baseline. The ARCLs were developed for the remaining roots using demineralisation solution (pH-4.8). 15-ARCLs samples were then left untreated. The rest of samples were divided into four groups (n = 15 each) and treated with Group-1(BG with 540ppm-F); Group-2(5000ppm-F); Group-3(1450ppm-F) and Group-4(deionised water). 13-day pH-cycling included using demineralisation solution for 6 h, then placing samples into remineralisation solution (pH-7) for 16 h. Each sample was brushed with the assigned toothpaste twice a day during pH-cycling. Fluoride concentrations at each time point were measured using F-ISE, whilst calcium (Ca2+) and phosphorus (P) ion release was determined using ICP-OES, KHN, XRD, 19F-MAS-NMR analyses. RESULTS: KHN showed significant surface changes for each group (p<0.001). The uptake of Ca2+ occurred at days 1-2, phosphorus ion loss was high when compared to the uptake in all groups. XRD showed presence of sharp diffraction lines evidencing apatite formation for Groups 1-3. 19F-MAS-NMR confirmed fluorapatite presence in Groups 1-3. CONCLUSION: All toothpastes were promising in fluorapatite formation. BG with 540ppm-F toothpaste released more ions (Ca2+and P) and reharden the artificial root carious lesions when compared to other groups. However, 1450ppm-F toothpaste showed more fluoride-substituted apatite formation whilst 5000ppm-F toothpaste had more fluorapatite formation. CLINICAL SIGNIFICANCE: Toothpaste containing BG with 540ppm-F, 5000ppm-F and 1450ppm-F toothpastes are likely to have a significant impact in reversing and arresting root caries. However, randomised controlled double-blinded clinical trials are required to translate these results into clinical practice.

Evaluation of caries arresting potential of silver diamine fluoride and sodium fluoride varnish in primary molars: A randomized controlled trial.

Background: Caries management in the modern era has shifted away from the traditional surgical method toward a medical paradigm, which often includes fluoride therapy. Fluoride used in various forms has been proven to be effective in dental caries prevention. Silver diamine fluoride (SDF) and sodium fluoride (NaF) varnish are effective in arresting caries in primary molars. Aim: This study aimed to evaluate the effectiveness of 38% SDF and 5% NaF varnish in arresting caries in primary molars. Settings and Design: This study was a split-mouth randomized controlled trial. Materials and Methods: The randomized controlled trial comprised 34 children aged 6-9 years with teeth having caries in both right and left primary molars without pulpal involvement. Teeth were randomly allocated into two groups. In Group 1 (n = 34), 38% SDF + potassium iodide was applied and in Group 2 (n = 34), 5% NaF varnish was applied. The second application was done after 6 months in both groups. Children were recalled at 6- and 12-month intervals and evaluated for caries arrest. Statistical Analysis: Chi-square test was used to analyze the data. Results: Caries arresting potential was found to be higher in the SDF group compared to the NaF varnish group at both 6-month (SDF - 82% and NaF varnish - 45%) and 12-month intervals (SDF - 77% and NaF varnish - 42%) and the difference was found to be statistically significant (P = 0.002 and 0.004, respectively). Conclusion: SDF was more effective in arresting dental caries in primary molars compared to 5% NaF varnish.

DNA-assisted upconversion nanoplatform for imaging-guided synergistic therapy and laser-switchable drug detoxification.

The side effects of chemotherapy bring significant physical and psychological suffering to patients. To solve this urgent medical problem, Yb3+ and Er3+ co-doped NaLuF4 upconversion nanoparticles (UCNPs) were constructed for upconversion luminescence (UCL)-labeled diagnosis under 980 nm laser irradiation. The UCNPs were then modified layer by layer with polypyrrole and a special programming DNA segment as photothermal conversion agents and controllable drug carriers, respectively. The nanoplatform was successfully used for imaging-guided synergistic therapy (photothermal therapy and chemotherapy) at a safe power density (300 mW cm-2), and DNA-assisted detoxification at lower temperature in cancer cells when the laser off. The synergistic therapy of the nanoplatform achieved a higher therapeutic index (∼85%) than chemotherapy only (∼44%) and photothermal therapy only (∼25%) in vitro. In vivo experiments also suggested that the nanoplatform had a higher therapeutic effect and lower side effects. The toxicity study was also evaluated, indicating the nanoplatform is low toxic to living system. This multifunctional upconversion nanoplatform provided an innovative method for imaging-guided photothermal-chemotherapy and laser-switchable drug detoxification.

Remineralizing Potential of a Low Fluoride Toothpaste with Sodium Trimetaphosphate: An in situ Study.

OBJECTIVE: To evaluate the effect of a low-fluoride (F) toothpaste supplemented with sodium trimetaphosphate (TMP) on enamel remineralization in situ. DESIGN: Bovine enamel blocks were selected on the basis of their surface hardness (SH) after caries-like lesions had been induced, and randomly divided into 4 treatment groups, according to the toothpastes used: without F or TMP (placebo); 500 ppm F; 500 ppm F plus 1% TMP; and 1,100 ppm F. The study design was blinded and crossover and performed in 4 phases of 3 days each. Eleven subjects used palatal appliances containing 4 bovine enamel blocks which were treated 3 times per day during 1 min each time, with natural slurries of saliva and toothpaste formed in the oral cavity during toothbrushing. After each phase, the percentages of surface (%SHR) and subsurface hardness recovery (%ΔKHNR) were calculated. F, calcium (Ca), and phosphorus (Pi) contents in enamel were also determined. Data were analyzed by 1-way, repeated-measures ANOVA, followed by the Student-Newman-Keuls test (p < 0.05). RESULTS: Toothpaste with 500 ppm F + TMP and 1,100 ppm F showed similar %SHR and %ΔKHNR as well as enamel F, Ca, and Pi concentrations. CONCLUSION: The addition of TMP to a low-fluoride toothpaste promoted a similar remineralizing capacity to that of a standard (1,100 ppm F) toothpaste in situ.

Fluoride varnish or fluoride mouth rinse? A comparative study of two school-based programs.

OBJECTIVE: In many Danish communities, school-based fluoride programs are offered to children with high caries risk in adjunct to tooth brushing. The purpose of this field trial was to compare the caries-preventive effectiveness of two different fluoride programs in 6-12 year olds. BASIC RESEARCH DESIGN: Clinical controlled trial. CLINICAL SETTING: The 2-year study was conducted in Public Dental Clinics in a multicultural low-socioeconomic suburban area of Odense, Denmark with an elevated prevalence of caries compared to the city average. PARTICIPANTS: 1,018 children (aged 6-12 years) from 9 different schools were enrolled after informed consent and their class unit was randomly allocated to one of two fluoride programs. INTERVENTIONS: One group received a semi-annual fluoride varnish applications (FV) and the other group continued with an existing program with fluoride mouth rinses once per week (FMR). All children received oral hygiene instructions and comprehensive dental care at the local Public Dental Clinics throughout the study period. MAIN OUTCOME MEASURES: Increment of caries lesions in permanent teeth at both cavitated and initial caries levels. RESULTS: The groups were balanced at baseline. After two years, 961 children (94.4%) were reexamined. The FV group showed a mean DMFS increment of 0.36 compared to 0.41 in the FMR group. The corresponding values for initial caries lesions were 0.83 and 0.91 respectively. CONCLUSION: There were no statistically significant differences in caries development over two years among children participating in a school-based fluoride varnish or mouth rinse program.

Comparing three toothpastes in controlling plaque and gingivitis: A 6-month clinical study.

PURPOSE: To investigate the clinical efficacy of three toothpastes in controlling established gingivitis and plaque over 6 months. METHODS: 135 subjects were enrolled in a single-center, double-blind, parallel group, randomized clinical study. Subjects were randomly assigned to one of three treatments: triclosan/copolymer/fluoride dentifrice containing 0.3% triclosan, 2.0% copolymer and 1,450 ppm F as sodium fluoride in a silica base; herbal/bicarbonate dentifrice containing herbal extract and 1,400 ppm F as sodium fluoride in a sodium bicarbonate base; or fluoride dentifrice containing 450 ppm F as sodium fluoride, and 1,000 ppm F as sodium monofluorophosphate. Subjects were instructed to brush their teeth twice daily for 1 minute for 6 months. RESULTS: After 6 months, subjects assigned to the triclosan/copolymer/fluoride group exhibited statistically significant reductions in gingival index scores and plaque index scores as compared to subjects assigned to the herbal/bicarbonate group by 35.4% and 48.9%, respectively. There were no statistically significant differences in gingival index and plaque index between subjects in the herbal/ bicarbonate group and those in the fluoride group. The triclosan/copolymer/fluoride dentifrice was statistically significantly more effective in reducing gingivitis and dental plaque than the herbal/bicarbonate dentifrice, and this difference in efficacy was clinically meaningful.

Effects of dentifrices on subsurface dentin tubule occlusion: an in situ study.

PURPOSE: To evaluate, in situ, the penetration of deposits formed within the subsurface of dentin samples treated with desensitizing dentifrices designed to occlude dentin tubules compared to two controls. MATERIALS AND METHODS: Twenty-eight healthy participants wore left and right intraoral appliances, each retaining four human dentin samples, for two periods of 4 days. Samples were power-brushed, outside the mouth, twice daily with test products (dentifrices containing 8% strontium or 8% arginine) or control (1,450 ppm NaF or water) and subjected to an agitated grapefruit juice acid challenge on days 3 and 4. Eighteen dentin samples were randomly selected from each treatment group and were dry fractured for scanning electron microscopy and energy-dispersive x-ray spectroscopy analysis. RESULTS: The proportion of cross-sectioned dentin tubules with subsurface occlusion (occluded to a mean of 5 ± 2 µm, range: 1 to 9 µm below the surface) for the 8% strontium group on days 1 and 2 (pre-acid) was 82% (SD: 9%, 95% confidence interval [CI] = 78% to 86%) and on days 3 and 4 (post-acid) was 88% (SD: 10%, CI = 83% to 93%). For 8% arginine on days 3 and 4 (post-acid), the proportion was 78% (SD: 8%, CI = 74% to 82%). These results were statistically significant compared to those for controls (P < .01). The 8% arginine on days 1 and 2 (pre-acid) and water and control paste on all days revealed no subsurface deposit. CONCLUSIONS: Within the limitations of this study, cross-sectional SEM analysis suggested strontium and arginine dentifrices occlude tubules subsurface in dentin compared to negative controls following acid challenge. The desensitizing dentifrices elicit subsurface changes that may potentiate their effects for the management of dentin hypersensitivity, particularly for patients who consume acidic beverages.

Changes in composition and enamel demineralization inhibition activities of gallic acid at different pH values.

BACKGROUND: Gallic acid (GA) has been shown to inhibit demineralization and enhance remineralization of enamel; however, GA solution is highly acidic. This study was to investigate the stability of GA solutions at various pH and to examine the resultant effects on enamel demineralization. METHODS: The stability of GA in H2O or in phosphate buffer at pH 5.5, pH 7.0 and pH 10.0 was evaluated qualitatively by ultraviolet absorption spectra and quantified by high performance liquid chromatography with diode array detection (HPLC-DAD). Then, bovine enamel blocks were subjected to a pH-cycling regime of 12 cycles. Each cycle included 5 min applications with one of the following treatments: 1 g/L NaF (positive control), 4 g/L GA in H2O or buffered at pH 5.5, pH 7.0 and pH 10.0 and buffers without GA at the same pH (negative control), followed by a 60 min application with pH 5.0 acidic buffers and a 5 min application with neutral buffers. The acidic buffers were analysed for dissolved calcium. RESULTS: GA was stable in pure water and acidic condition, but was unstable in neutral and alkaline conditions, in which ultraviolet spectra changed and HPLC-DAD analysis revealed that most of the GA was degraded. All the GA groups significantly inhibited demineralization (p < 0.05) and there was no significant difference of the inhibition efficacy among different GA groups (p > 0.05). CONCLUSIONS: GA could inhibit enamel demineralization and the inhibition effect is not influenced by pH. GA could be a useful source as an anti-cariogenic agent for broad practical application.

The influence of varnish and high fluoride on erosion and abrasion in a laboratory investigation.

BACKGROUND: The aim of this study was to investigate the potential of concentrated fluoride varnishes to reduce enamel loss from repeated cycles of citric acid erosion and toothbrush abrasion in vitro. METHODS: Polished human enamel samples were exposed to fluoride varnishes: Bifluorid10® (NaF&CaF2- 45,200 ppmF), Duraphat® (NaF 22,600 ppmF), Fluor-Protector® (difluorsilane 1000 ppmF) and a control coating of copal ether varnish (0 ppmF) group and a deionized water group. For each group of 16 samples, nine cycles of erosion and nine cycles of erosion-abrasion [1 cycle=erosion (0.3% citric acid, pH 3.2, 5 min)+artificial saliva (1 h, pH 7.0)+abrasion (120 linear strokes in artificial saliva from Oral B medium soft brushes 300 g loading]. The change in the enamel surface was evaluated using optical profilometry. RESULTS: Duraphat® and Bifluorid10® applications had a median (IQR) step height of 4.21 um (1.59) and 5.01 um (1.02). This was statistically significantly less than Fluor-Protector® 6.83 um (1.25), copal ether 7.22 um (1.97) and water 7.39 um (1.96) (p<0.001). For erosion-abrasion, both Duraphat® and Bifluorid® had statistically lower step heights than the other products (p<0.01). CONCLUSIONS: The action of fluoride in a range of single-application topical varnishes was effective in reducing enamel wear from erosion and erosion-abrasion in this laboratory study.

A Randomized Clinical Study Investigating the Stain-Removal Potential of Two Experimental Dentifrices.

OBJECTIVE: To evaluate the ability of two experimental desensitizing dentifrices, both containing a chemical cleaning agent, one with ultra-low abrasivity and one with low abrasivity, a standard fluoride dentifrice, and a daily-use whitening dentifrice to remove extrinsic tooth stain. METHODS: This was a single-center, examiner-blind, randomized, controlled, four-treatment, parallel-group study in healthy adults. Extrinsic stain was evaluated using the Macpherson modification of the Lobene Stain Index (MLSI). At baseline, eligible subjects with a total MLSI (area x intensity [A x I]) score of 15 for the facial surfaces of the 12 anterior teeth were stratified (based on total MLSI [A x I] score [< 45 = low; ≥ 45 = high] and smoking status) and randomized to treatment with one of four dentifrices: an experimental ultra-low abrasivity desensitizing dentifrice (relative dentin abrasion [RDA] -12); an experimental low abrasivity desensitizing dentifrice (RDA -40); a standard fluoride dentifrice with moderate abrasivity (RDA -80); and a whitening dentifrice with higher abrasivity (RDA -142). Both desensitizing dentifrices contained 5% potassium nitrate and 5% sodium tripolyphosphate (a chemical cleaning agent). Treatment effects were evaluated after four and eight weeks of twice-daily brushing. RESULTS: In total, 142 subjects were randomized and 133 subjects completed the study. All study dentifrices demonstrated statistically significant reductions in extrinsic tooth stain from baseline after four and eight weeks of twice-daily use (p < 0.01). There were no statistically significant between-treatment differences for the primary variable (mean MLSI [A x I] score across all assessed sites) at four or eight weeks, and no notable trends were observed. CONCLUSION: All study dentifrices reduced extrinsic tooth stain. The experimental ultra-low and low abrasivity desensitizing dentifrices containing 5% sodium tripolyphosphate performed similarly to both a moderate abrasivity standard fluoride dentifrice and a higher abrasivity whitening dentifrice.

Efficacy of tooth bleaching with the prior application of a desensitizing agent.

AIM: In the present study, we evaluated the efficacy of bleaching on enamel and opposite dentin surfaces using 35% hydrogen peroxide (HP) with the prior application of a desensitizing agent. METHODS: Thirty bovine dental fragments, with thicknesses of 1 mm enamel and 1.75 mm dentin, were stained in a solution of black tea. The fragments were randomly divided into three groups (n = 10) according to the following protocols: (a) 2% neutral fluoride + bleaching; (b) desensitizing agent + bleaching; and (c) without desensitizer + bleaching. The bleaching efficacy was evaluated four times: after staining with tea (baseline) and after each of the 3 weeks of bleaching, by means of the CIE Lab method using a reflectance spectrophotometer. The data coordinate L* was evaluated by an analysis of repeated measures with PROC MIXED and Tukey-Kramer's test. The ΔE values were subjected to anova and Tukey's test (α = 0.05). RESULTS: The 35% HP treatment showed greater efficacy on deep dentin after removal of the enamel stains, with increasing means during all times in all treatments. CONCLUSION: The use of a desensitizing agent prior to the bleaching session did not affect the mechanism of action of 35% HP with regard to tooth depth.

Effectiveness of varnish with CPP-ACP in prevention of caries lesions around orthodontic brackets: an OCT evaluation.

OBJECTIVE: To evaluate the in vitro efficiency of applying varnish containing casein phosphopeptide (CPP) and amorphous calcium phosphate (ACP) in prevention of caries lesions around orthodontic brackets. MATERIALS AND METHODS: For this purpose, brackets were bonded to the vestibular surface of bovine incisors, and eight groups were formed (n = 15) according to exposure of oral hygiene substances and enamel varnish: 1 (control) brushing only performed, 2 (control) brushing + use of mouth wash with fluoride, 3 Duraphat varnish application only (Colgate-Palmolive Ind. E Com. Ltda, São Paulo, SP, Brazil), 4 Duraphat + brushing, 5 Duraphat + brushing + mouth wash, 6 MI Varnish application (GC America, USA), 7 MI + brushing, and 8 MI + brushing + mouth wash. The experimental groups alternated between pH cycling and the procedures described and were kept in an oven at temperature of 37°C. Both brushing and immersion in solutions was performed in a time interval of 1 minute, followed by washing in deionized water three times a day for 28 days of experimentation. Afterwards, evaluation by optical coherence tomography (OCT) of the special type (Ganymede OCT/Thorlabs, Newton, USA) was performed. In each group, a scanning exam of the white spot lesion area (around the region where brackets were bonded) and depth measurement of caries lesions were performed. RESULTS: Groups 1 and 3 were shown to differ statistically from groups 5, 6, 7, and 8 (p = 0.000). MI Varnish was shown to be more effective in diminishing caries lesion depth, compared with Duraphat, irrespective of being associated with brushing and mouth wash, or not. LIMITATIONS: The major limitation of this study is that it is a study in which demineralization was obtained with the use of chemical products, and did not occur due to the presence of Streptococcus mutans and its acid byproducts. CONCLUSION: Application CPP-ACP-containing varnish irrespective of being associated with brushing and mouthwash, or not, reduced depth of caries lesions around orthodontic brackets.

The combined use of Er,Cr:YSGG laser and fluoride to prevent root dentin demineralization.

UNLABELLED: The use of erbium lasers to prevent caries in enamel has shown positive results. However, it is not known if Er,Cr:YSGG laser can also be used to increase acid resistance of root dentine, which is another dental tissue susceptible to the action of cariogenic bacteria. OBJECTIVE: To analyze the effects of the Er,Cr:YSGG laser (λ=2.78 µm, 20 Hz) irradiation associated with 2% neutral sodium fluoride (NaF) to prevent root dentin demineralization. MATERIAL AND METHODS: One hundred human root dentin samples were divided into 10 groups (G) and treated as follows: G1: no treatment; G2: NaF; G3: laser (4.64 J/cm2) with water cooling (WC=5.4 mL/min); G4: laser (4.64 J/cm2) without WC; G5: laser (8.92 J/cm2) with WC; G6: laser (8.92 J/cm2) without WC; G7: laser (4.64 J/cm2) with WC and NaF; G8: laser (4.64 J/cm2) without WC and NaF; G9: laser (8.92 J/cm2) with WC and NaF; G10: laser (8.92 J/cm2) without WC and NaF. The NaF gel was applied alone or after 4 min of irradiation. After 14 days of acid challenge, the samples were sectioned and the Knoop microhardness (KHN) test was done at different depths (30, 60, 90 and 120 µm) from the outer dentin surface. Data were analyzed by one-way ANOVA and Fisher's test (α=5%). RESULTS: The results showed that G8 and G10 presented higher KHN than the G1 for the depths of 30 and 60 µm, indicating an increase of the acid resistance of the dentin in up to 35% (p<0.05). CONCLUSIONS: The use of Er,Cr:YSGG laser irradiation at 4.64 J/ cm2 and 8.92 J/cm2 without water cooling and associated with 2% NaF can increase the acid resistance of human root dentin.

The combined use of Er, Cr: YSGG laser and fluoride to prevent root dentin demineralization

The use of erbium lasers to prevent caries in enamel has shown positive results. However, it is not known if Er,Cr:YSGG laser can also be used to increase acid resistance of root dentine, which is another dental tissue susceptible to the action of cariogenic bacteria. Objective: To analyze the effects of the Er,Cr:YSGG laser (λ=2.78 μm, 20 Hz) irradiation associated with 2% neutral sodium fluoride (NaF) to prevent root dentin demineralization. Material and Methods: One hundred human root dentin samples were divided into 10 groups (G) and treated as follows: G1: no treatment; G2: NaF; G3: laser (4.64 J/cm2) with water cooling (WC=5.4 mL/min); G4: laser (4.64 J/cm2) without WC; G5: laser (8.92 J/cm2) with WC; G6: laser (8.92 J/cm2) without WC; G7: laser (4.64 J/cm2) with WC and NaF; G8: laser (4.64 J/cm2) without WC and NaF; G9: laser (8.92 J/cm2) with WC and NaF; G10: laser (8.92 J/cm2) without WC and NaF. The NaF gel was applied alone or after 4 min of irradiation. After 14 days of acid challenge, the samples were sectioned and the Knoop microhardness (KHN) test was done at different depths (30, 60, 90 and 120 μm) from the outer dentin surface. Data were analyzed by one-way ANOVA and Fisher’s test (α=5%). Results: The results showed that G8 and G10 presented higher KHN than the G1 for the depths of 30 and 60 μm, indicating an increase of the acid resistance of the dentin in up to 35% (p<0.05). Conclusions: The use of Er,Cr:YSGG laser irradiation at 4.64 J/ cm2 and 8.92 J/cm2 without water cooling and associated with 2% NaF can increase the acid resistance of human root dentin. .

Effects of oil-based and oil-free enamel prophylactic agents on bracket failure--a prospective randomized clinical trial.

This study evaluates and compares the effects of enamel prophylaxis using either oil-free pumice or oil-containing prophylaxis paste on the incidence of bracket failure in orthodontic patients. Forty-six orthodontic patients participated in this prospective clinical trial. A cross-mouth method was used in each patient, in which two diagonal quadrants (i.e. upper right and lower left or vice versa) were randomly assigned to the pumice group and the contralateral diagonal quadrants to the Prophy Paste group. A total of 836 teeth were bonded using Transbond XT (3M Unitek) and monitored for an average of 23 months for bond failure. Chi-square analysis was used to compare the number of bracket failures between the groups. Overall, 26 bond failures occurred by the end of the trial. Fifteen bracket failures were observed in the Prophy Paste group (3.6%) and 11 in the pumice group (2.6%). The failure rates were fairly evenly distributed between the upper and lower jaws. There were no statistically significant differences between the groups (P = 0.43). This study showed that enamel prophylaxis using either pumice or Prophy Paste before orthodontic bonding works equally well in a clinical setting.

Anacardic acid from brazilian cashew nut trees reduces dentine erosion.

The aim of this study was to analyze the effect of solutions containing saturated anacardic acid (AA) on dentine erosion in vitro. AA was chemically isolated from natural cashew nutshell liquid obtained by continuous extraction in a Soxhlet extractor and was fully saturated by catalytic hydrogenation. Matrix metalloproteinase 2 (MMP-2) activity, when exposed to buffers containing 100 µmol/l AA, was analyzed using zymography. Bovine root samples were subjected to erosive demineralization (Sprite Zero™, 4 × 90 s/day) and remineralization with artificial saliva between the erosive cycles for 5 days. The samples were treated as follows, after the first and the last acid exposure (1 min; n = 12/group): (1) 100 µmol/l epigallocatechin-3-gallate (EGCG) (positive control); (2) 0.05% NaF; (3) 100 µmol/l saturated AA; (4) saturated AA and EGCG; (5) saturated AA, EGCG and NaF; (6) untreated (negative control). Dentine erosion was measured using a contact profilometer. Two dentine samples from each group were analyzed using scanning electron microscopy. Saturated AA reduced the activity of MMP-2. ANOVA and Tukey's test revealed that all treatments significantly reduced dentine loss compared to the negative control (6.03 ± 0.98 µm). Solutions containing saturated AA (1.97 ± 1.02 µm) showed the greatest reduction in dentine erosion compared to the NaF (3.93 ± 1.54 µm) and EGCG (3.79 ± 0.83 µm) solutions. Therefore, it may be concluded that AA significantly reduces dentine erosion in vitro, possibly by acting as an MMP-2 inhibitor.

Community-level assessment of dental plaque bacteria susceptibility to triclosan over 19 years.

BACKGROUND: Triclosan is a broad-spectrum antimicrobial agent used in toothpaste to reduce dental plaque, gingivitis and oral malodor. This community-level assessment evaluated the susceptibility of dental plaque bacteria to triclosan in samples collected over 19 years. METHODS: A total of 155 dental plaque samples were collected at eleven different times over 19 years from 58 adults using 0.3% triclosan, 2% copolymer, 0.243% sodium fluoride toothpaste and from 97 adults using toothpaste without triclosan. These included samples from 21 subjects who used triclosan toothpaste for at least five years and samples from 20 control subjects. The samples were cultured on media containing 0, 7.5 or 25 µg/ml triclosan. Descriptive statistics and p values were computed and a linear regression model and the runs test were used to examine susceptibility over time. RESULTS: Growth inhibition averaged 99.451% (91.209 - 99.830%) on media containing 7.5 µg/ml triclosan and 99.989% (99.670 - 100%) on media containing 25 µg/ml triclosan. There was no change in microbial susceptibility to triclosan over time discernible by regression analysis or the runs test in plaque samples taken over 19 years including samples from subjects using a triclosan-containing dentifrice for at least five years. CONCLUSIONS: This community-level assessment of microbial susceptibility to triclosan among supragingival plaque bacteria is consistent with the long-term safety of a 0.3% triclosan, 2% copolymer, 0.243% sodium fluoride dentifrice.