Dentin erosive wear is reduced by fluoride varnishes containing nanosized sodium trimetaphosphate in vitro.

This study evaluated the effect of fluoride varnishes containing micrometric or nanosized sodium trimetaphosphate (TMP) on dentin erosive wear in vitro. Bovine root dentin blocks were selected by surface hardness and randomly divided into five experimental groups/varnishes (n = 20/group): placebo, 5% sodium fluoride (NaF); 5% NaF+5% micrometric TMP; 5% NaF+2.5% nanosized TMP; and 5% NaF+5% nanosized TMP. Half of the surface of all blocks received a single application of the assigned varnish, with subsequent immersion in artificial saliva for 6 h. Varnishes were then removed and the blocks were immersed in citric acid (90 s, 4×/day, 5 days). After each erosive cycle, ten blocks of each group were immersed in a placebo dentifrice for 15 s (ERO), while the other ten blocks were subjected to abrasion by brushing (ERO+ABR). Dentin erosive wear was assessed by profilometry. Data were submitted to 2-way ANOVA and to the Holm-Sidak test (p<0.05). Dentin erosive wear was significantly higher for ERO+ABR than for ERO for all varnishes. TMP-containing varnishes promoted superior effects against dentin erosive wear compared with 5% NaF alone; and 5% nanosized TMP led to the lowest wear among all varnishes. In conclusion, the addition of TMP to conventional fluoride varnish (i.e., varnish containing only NaF) enhanced its protective effects against bovine root dentin erosion and erosion+abrasion. Additionally, the use of 5% nanosized TMP led to superior effects in comparison to 5% micrometric TMP, both for erosion and erosion+abrasion in vitro.

Marginal integrity of prototype bioactive glass-doped resin composites in class II cavities.

OBJECTIVES: This in vitro study examined the marginal integrity of experimental composite materials doped with bioactive glass (BG). MATERIALS AND METHODS: Class-II MOD cavities were prepared and restored with one of the following composite materials: a commercial composite material as a reference (Filtek Supreme XTE), an experimental composite doped with BG 45S5 (C-20), and an experimental composite doped with a fluoride-containing BG (F-20). Six experimental groups (n = 8) were used, as each of the three composites was applied with (+) or without (-) a universal adhesive (Adper Scotchbond Multipurpose). All specimens were subjected to thermocycling (10,000 x, 5-55 °C) and then additionally stored in artificial saliva for eight weeks. Scanning electron micrographs of the mesial and the distal box were taken at three time points (initial, after thermocycling, and after eight weeks of storage in artificial saliva). The margins were classified as "continuous" and "non-continuous" and the percentage of continuous margins (PCM) was statistically analyzed (α = 0.05). RESULTS: In most experimental groups, thermocycling led to a significant decrease in PCM, while the additional 8-week aging had no significant effect. F-20 + performed significantly better (p = 0.005) after 8 weeks storage in artificial saliva than the reference material with adhesive, while no statistically significant differences were observed at the other two time points. C-20 + exhibited significantly better PCM than the reference material with adhesive after thermocycling (p = 0.026) and after 8 weeks (p = 0.003). CONCLUSIONS: Overall, the experimental composites with BG showed at least as good marginal adaptation as the commercial reference, with an indication of possible re-sealing of marginal gaps. CLINICAL RELEVANCE: Maintaining or improving the marginal integrity of composite restorations is important to prevent microleakage and its likely consequences such as pulp irritation and secondary caries.

Evaluation of Surface Roughness and Microhardness of Bulk-fill and Nanohybrid Composite after Exposure to Different Beverages at Various Time Intervals - An In vitro Study.

AIM: The aim of the study was to compare the surface roughness and microhardness of bulk-fill composite and nanohybrid composite resin after exposure to three different beverages at different time intervals. METHODOLOGY: In this study, 60 composite discs each for bulk fill and nanohybrid, of dimensions 10 mm × 2 mm were made. Both composites were randomly divided into four subgroups, i.e., 15 samples each for artificial saliva, tea, coffee, and soft drinks which were further subdivided into five samples for three time intervals. Composite resin discs were immersed in beverages for 4 min in 24 h for 7, 15, and 30 days. All samples were evaluated for surface roughness and microhardness before and after immersion. RESULTS: Both the composites showed a significant increase in surface roughness in all the beverages with maximum change in surface roughness observed in nanohybrid composite resin immersed in soft drinks. Furthermore, the microhardness of both the composites was decreased significantly in all beverages with maximum change in microhardness observed in nanohybrid composite resin immersed in soft drinks. CONCLUSIONS: Bulk-fill composite resin has better resistance to surface roughness and higher microhardness as compared to nanohybrid. Furthermore, acidic beverages highly affect the physical properties of both composite resins for longer periods.

Résumé Objectif:Comparer la rugosité de surface et la microdureté du composite Bulk-Fill et de la résine composite nanohybride après exposition à trois boissons différentes à différents intervalles de temps.Matériels et Méthodes:Dans cette étude, 60 disques composites chacun pour remplissage en vrac et nanohybride, de dimensions 10 mm X 2 mm ont été fabriqués. Les deux composites ont été divisés au hasard en quatre sous-groupes, soit 15 échantillons chacun pour la salive artificielle, le thé, le café et les boissons gazeuses, qui ont ensuite été subdivisés en 5 échantillons pendant 3 intervalles de temps. Des disques de résine composite ont été immergés dans des boissons pendant 4 minutes en 24 heures pendant 7, 15 et 30 jours. Tous les échantillons ont été évalués pour la rugosité de surface et la microdureté avant et après immersion.Résultats:Les deux composites ont montré une augmentation significative de la rugosité de surface dans toutes les boissons, un changement maximal de rugosité de surface ayant été observé dans la résine composite nanohybride immergée dans une boisson gazeuse. De plus, la microdureté des deux composites a diminué de manière significative dans toutes les boissons, un changement maximal de microdureté ayant été observé dans la résine composite nanohybride immergée dans une boisson gazeuse.Conclusions:La résine composite de remplissage en vrac a une meilleure résistance à la rugosité de surface et une microdureté plus élevée que la nanohybride. De plus, les boissons acides affectent fortement les propriétés physiques des deux résines composites sur des périodes plus longues.

Effects of Water Sorption and Solubility on Degradation of Silorane and Methacrylate-Based Dental Composites.

INTRODUCTION: Wet oral environment may have deleterious effects on performance of the composites due to influences of water sorption and solubility. The study evaluated the hydrolytic degradation caused because of water sorption and solubility of silorane and methacrylate-based dental composites. METHODS: Ten disc samples (2 mm × 10 mm) were prepared. Samples were analyzed for water solubility and sorption according to ISO 4049:2000 regulations and tested for mass gain or loss following immersion in water or in artificial saliva at 1 day, 15 days, and 30 days period. Student's 't' test, repeated measures analysis of variance (ANOVA), and Tukey's post-hoc tests determined statistical significance of the experimental results with global significance set at P = 0.05. RESULTS: Considerable sorption and solubility was observed with time in both materials on immersion. Silorane composites showed lower water sorption and solubility than methacrylate-based composite (MBC). Artificial saliva demonstrated higher sorption and solubility compared to distilled water. CONCLUSION: Silorane composites display enhanced hydrolytic stability even after a month of immersion in contrast to conventional methacrylate-based composites (MBCs), making it a better alternative to MBC resins clinically.

Evaluation of wear resistance and surface properties of additively manufactured restorative dental materials.

OBJECTIVES: To evaluate the wear resistance of three additively manufactured dental crown materials (NextDent C&B MFH, Saremco print CROWNTEC and Bego VarseoSmile Crown) under two environmental conditions (dry and artificial saliva), two loads (49 N and 70 N) and two surface treatments (polished and glazed). METHODS: A total of 120 specimens were divided into 24 groups and tested for wear under two loads (49 N and 70 N), surface treatment (polished or glazed), and environment (dry or submerged in artificial saliva). All samples underwent reciprocating wear testing at 1 Hz using a wear simulator, replicating 48 months of In Vivo conditions with a stainless-steel ball as the antagonist. The coefficient of friction (CoF), surface roughness, volumetric and vertical wear loss were measured and statistically analysed. Confocal microscopy assessed the surface properties of crown materials and the antagonists. RESULTS: The NextDent material demonstrated the most homogenous wear, with relatively low vertical and volumetric loss across all groups (p < 0.004). NextDent and Bego materials performed similarly in artificial saliva regardless of the load type (p > 1.000). The CoF remained below 0.3 for all groups. All groups exhibited significant increases in surface roughness after testing, however, this did not correlate with an increase in the CoF. Confocal analysis revealed material deformities due to load and notable scratch marks on the stainless-steel antagonists. CONCLUSION: It was found that all investigated addtively manufactured materials can be suggested for provisional use. Both vertical loss and volumetric loss results should be included for material evaluation. CoF and surface roughness should be implemented into wear evaluation. CLINICAL SIGNIFICANCE: This study highlights the practical value of additively manufactured dental crown materials, particularly for provisional restorations. However, their extended use requires careful consideration of individual patient needs, emphasising the need for judicious clinical application evaluation.

Evaluation of baghdadite (Ca3ZrSi2O9) cements for the application as novel endodontic filling materials.

OBJECTIVES: Baghdadite (Ca3ZrSi2O9) cements of various composition have been investigated in this study regarding an application as endodontic filling materials. METHODS: Cements were either obtained by mixing mechanically activated baghdadite powder with water (maBag) or by subsequently substituting the ß-tricalcium phosphate (ß-TCP) component in a brushite forming calcium phosphate cement. The cements were analyzed for their mechanical performance, injectability, radiopacity, phase composition and antimicrobial properties. RESULTS: The cements demonstrated sufficient mechanical performance with a compressive strength of ∼1 MPa (maBag) and 2.3 - 17.4 MPa (substituted calcium phosphate cement), good injectability > 80 % depending on the powder to liquid ratio and an intrinsic radiopacity of 1.13 - 2.05 mm aluminum equivalent. Immersion in artificial saliva proved their bioactivity by the formation of calcium phosphate and calcium silicate precipitates on the cement surface. The bacterial activity of Staphylococcus aureus cultured on the surface of the cements was found to be similar compared to clinical standard ProRoot MTA cement or even reduced by a factor of 3 for Streptococcus mutans. SIGNIFICANCE: In combination with their antibacterial properties, baghdadite cements are thought to have the potential to fulfil the clinical requirements for endodontic filling materials.

On the rheological and sensory properties of a novel natural salivary substitute.

The prevalence of xerostomia, the sensation of dry mouth, is estimated at 20 % in the general population and up to 50 % in older adults. Saliva plays different roles during bolus formation: lubrication, mixing, coating, hydration, dissolution, and comminution of food particles. This study proposes and tests artificial saliva formulations mimicking human saliva rheological and sensory perceptions. Shear and extensional rheology were assessed to select the type of formulation closest to saliva rheological characteristics. After evaluating three alternative sources, an extract simulating saliva rheology was produced from flax seeds. Friction coefficient and rheological properties, such as flow curves, relaxation times, and Trouton ratios, were compared favorably with human saliva. The sensory evaluation demonstrated that flaxseed extracts induce perceived mouth hydration, slipperiness, and adhesion exceeding that of human saliva. The flaxseed extract proposed in this can i) be used to study in vitro food oral processing and ii) pave the way to novel natural salivary substitutes to alleviate the symptoms of xerostomia.

The in vitro assessment of rheological properties and dentin remineralization of saliva substitutes containing propolis and aloe vera extracts.

Saliva substitutes with enhanced dentin remineralization properties were expected to help manage caries progression in patients with xerostomia. This in vitro study examined the rheological properties and remineralization action of experimental saliva substitutes containing propolis extract and aloe vera extract on demineralized dentin. Four experimental saliva substitutes were formulated with varying concentrations of propolis extract (P) and aloe vera extract (A) were prepared. A commercial saliva substitute (Biotene Oral Rinse) was used as a commercial comparison. The rheological properties and viscosity of these materials were measured using a strain-controlled rheometer (n = 3). The remineralizing actions of saliva substitutes on demineralized dentin after 2 weeks were determined using ATR-FTIR and SEM-EDX (n = 8). The results were expressed as a percentage increase in the mineral-to-matrix ratio. Biotene demonstrated a significantly higher viscosity (13.5 mPa·s) than experimental saliva substitutes (p<0.05). The addition of extracts increased the viscosity of the saliva substitutes from 4.7 mPa·s to 5.2 mPa·s. All formulations showed minimal shear thinning behavior, which was the viscoelastic properties of natural saliva. The formulation containing 5 wt% of propolis exhibited the highest increase in the median mineral-to-matrix ratio (25.48%). The SEM-EDX analysis revealed substantial mineral precipitation in demineralized dentin, especially in formulations with 5 wt% or 2.5 wt% of propolis. The effect of the aloe vera extract was minimal. The addition of propolis and aloe vera extracts increased the viscosity of saliva substitutes. the addition of propolis for 2.5 or 5 wt% to saliva substitutes increased mineral apatite precipitation and tubule occlusion. To conclude, the saliva substitute containing propolis extract demonstrated superior remineralizing actions compared with those containing only aloe vera extract.

An investigation of the corrosion behavior of zinc-coated stainless steel orthodontic wires: the effect of physical vapor deposition method.

BACKGROUND: Releasing of metal ions might implicate in allergic reaction as a negative subsequent of the corrosion of Stainless Steel (SS304) orthodontic wires. The aim of this study was to evaluate the corrosion resistance of zinc-coated (Zn-coated) SS orthodontic wires. METHODS: Zinc coating was applied on SS wires by PVD method. Electrochemical impedance spectroscopy (EIS), Potentiodynamic polarization tests and Tafel analysis methods were used to predict the corrosion behavior of Zn-coated and uncoated SS wires in both neutral and acidic environments. RESULTS: The values of Ecorr ,icorr and Rct ,which were the electrochemical corrosion characteristics, reported better corrosion behavior of Zn-coated SS wires against uncoated ones in both artificial saliva and fluoride-containing environments. Experimental results of the Tafel plot analyses were consistent with that of electrochemical impedance spectroscopy analyses for both biological solutions. CONCLUSION: Applying Zn coating on bare SS orthodontic wire by PVD method might increase the corrosion resistance of the underlying stainless-steel substrate.

Salivary, acidic and enzymatic degradation of resin composite subjected to different finishing and polishing systems.

PURPOSE: To evaluate the effect of different finishing and polishing systems on the surface roughness of a resin composite subjected to simulated saliva-, acid-, and enzyme-induced degradation. METHODS: 160 specimens (n= 40) were fabricated with Filtek Z350 XT nanofilled composite and analyzed for average surface roughness (Ra). The specimens were finished and polished using: AD - Al2O3-impreginated rubberized discs (medium, fine, and superfine grit, Sof-Lex); SD - silicon carbide and Al2O3-impregnated rubberized discs (coarse, medium and fine grit, Jiffy,); MB - 12- and 30-multiblade burs. The control group (CT) (n= 40) comprised specimens with a Mylar-strip-created surface. Specimens from each group were immersed in 1 mL of one of the degradation methods (n= 10): artificial saliva (ArS: pH 6.75), cariogenic challenge (CaC: pH 4.3), erosive challenge (ErC: 0.05M citric acid, pH 2.3) or enzymatic challenge (EzC: artificial saliva with 700 µg/mL of albumin, pH 6.75). The immersion period simulated a time frame of 180 days. Ra measurements were also performed at the post-polishing and post-degradation time points. The data were evaluated by three-way ANOVA for repeated measures and the Tukey tests. RESULTS: There was significant interaction between the finishing/polishing system and the degradation method (P= 0.001). AD presented the greatest smoothness, followed by SD. After degradation, CT, AD and SD groups became significantly rougher, but not the MB group, which presented no difference in roughness before or after degradation. CT and AD groups showed greater roughness in CaC, ErC and EzC than in ArS. The SD group showed no difference in roughness when the specimens were polished with CaC, EzC or ArS, but those treated with ErC had greater roughness. In the MB group, the lower roughness values were found after using CaC and EzC, while the higher values were found using ErC or ArS. CLINICAL SIGNIFICANCE: As far as degradation resistance of nanofilled composite to hydrolysis, bacterial and dietary acids and enzymatic reactions is concerned, restorations that had been finished and polished with Al2O3-impregnated discs had the smoothest surfaces.

The effect of fluoride varnish application on colour change due to paediatric drug usage in polyacid-modified composite resin: an in vitro study.

OBJECTIVE: Colour stability is important in the long-term aesthetic success of restorative materials and is affected by both internal and external factors. Internal discolourations are due to the properties of the restorative materials. External discolourations can be associated with frequent consumption of food and beverages and the use of suspensions or syrups containing colourants/additives. Fluoride varnish application has an important place in preventive dentistry. The purpose of the research was to examine the protective effect of fluoride varnish application on the colour change on polyacid-modified composite resin restorative materials caused by the use of various paediatric drugs. METHODS: Two hundred ten discs were prepared from polyacid-modified composite resin material and divided into two groups: flouride varnish was applied to one group and flouride varnish was not applied to the other group. The groups were further divided into seven subgroups and the samples were kept in artificial saliva, amoxicillin + clavulanic acid, cefuroxime axetil, clarithromycin, paracetamol, ibuprofen, and iron supplement drug solutions. The colour change values of the discs were measured using a spectrophotometer device before immersion in the drug solutions and on the 7th, 14th, 21st, and 28th days after the immersion. The obtained data were calculated and statistically evaluated using IBM SPSS V23 software. RESULTS: It was found that the application of fluoride varnish in the iron supplement drug group prevented the colour change of the polyacid-modified composite resins for 28 days. In the amoxicillin + clavulanic acid, cefuroxime axetil, and paracetamol groups, the fluoride varnish did not prevent colour change in the polyacid-modified composite resin restorative materials at the end of the 14th day. CONCLUSION: It is thought that fluoride varnish application may be beneficial as a preservative in the colour change of polyacid-modified composite resins due to the use of various paediatric drugs, and this protective feature may be effective for a specific period of time.

Analysis of Key Factors for Evaluating Mucosal Adhesion Using Swine Buccal Tissue.

The assessment of the mucoadhesive properties peak mucoadhesive force (Fmax) and work of mucoadhesion (Wmuc) with texture analyzers is a common in vitro method for analyzing formulation capabilities. Challenges arise in selecting and standardizing experimental conditions due to various variables influencing mucoadhesion. This complexity hampers direct product performance comparisons. In our study, we explored factors (contact force and time, probe speed and mucin in artificial saliva) impacting a model formulation's mucoadhesive capacity. Using Omcilon-A®Orabase on porcine buccal mucosa, we systematically varied experimental conditions, employing a statistical approach (Central Composite Design - CCD). Three variables (contact force, contact time, probe speed) and their interactions were assessed for their impact on Fmax and Wmuc. Results showed that contact time and force positively affected Fmax, while only contact time influenced Wmuc. In the mucin artificial saliva test, a force of 0.5 N, time of 600 s, and speed of 1 mm/s yielded optimal Fmax (0.587 N) and Wmuc (0.468 N.s). These conditions serve as a reference for comparing mucoadhesive properties of formulations for topical oral use.

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.

The effect of salbutamol sulphate inhalation (an anti-asthmatic medication) on the surfaces of orthodontic Archwires.

OBJECTIVES: This study aimed to compare the surface roughness and friction of different orthodontic archwires after exposure to salbutamol sulphate inhalation, an anti-asthmatic medication. METHODS: Orthodontic archwires (stainless-steel [StSt], nickel-titanium [NiTi], beta-titanium [ß-Ti], and copper-NiTi [Cu-NiTi]) were equally divided into two groups. The exposed groups were subjected to 20 mg salbutamol sulphate for 21 days and kept in artificial saliva. The control groups were only kept in artificial saliva. Surface changes were visualized using scanning electron microscopy (SEM). The average surface roughness (Ra) was evaluated using atomic force microscopy (AFM), and friction resistance forces were assessed using a universal testing machine. Statistical analyses were performed using t-tests and ANOVA followed by post hoc tests. RESULTS: Salbutamol sulphate did not change the surface roughness of StSt and NiTi archwires (p > .05). However, the change in the surfaces of ß-Ti and Cu-NiTi archwires was significant (p < .001). The frictional forces of exposed StSt, NiTi, and Cu-NiTi archwires did not change (p > .05). However, the frictional forces of ß-Ti archwires increased significantly after exposure to salbutamol sulphate (p = .021). Brushing with fluoride after exposure to salbutamol sulphate increased the frictional forces of ß-Ti only (p = .002). CONCLUSIONS: Salbutamol sulphate inhalation significantly affected the surface texture of ß-Ti and Cu-NiTi orthodontic archwires and increased the friction of ß-Ti archwires. These deteriorating effects were not detected on the surface of StSt and NiTi archwires. Therefore, we suggest that ß-Ti and copper titanium archwires should be used cautiously in individuals under salbutamol sulphate inhalation treatment.

Evaluation of Struthio camelus eggshell as an in vitro alternative to extracted human teeth in preliminary screening studies on dental erosion.

OBJECTIVES: This in vitro work investigates the potential of ostrich eggshell as a substitute for extracted human teeth in preliminary screening studies on dental erosion. Additionally, it aims to demonstrate the potential of ostrich eggshell compared to human enamel in evaluating the efficacy of a preventive agent in protecting against dental erosion, using an artificial mouth model. METHODS: The experiment utilized 96 erosion testing specimens from each substrate, human enamel, and ostrich eggshell. The specimens were subjected to six different experimental regimens of increasing erosive challenge, simulating the consumption of an acidic drink. The acidic drink was delivered at a consistent volume and duration range. Both artificially stimulated and unstimulated saliva flowed throughout the experimental regimens. Surface hardness was measured using a Through-Indenter Viewing hardness tester with a Vickers diamond, while surface profiling was done using a surface contacting profilometer with a diamond stylus. An automated chemistry analyzer system was used to detect calcium and phosphate ions. RESULTS: The study found that ostrich eggshell specimens demonstrated predictable surface loss, hardness drop, and ion loss due to the acidic challenge. Meanwhile, enamel appeared to fall short in terms of surface hardness predictability. The transient hardness loss phase, which manifests as an overlooked decrease in surface hardness despite significant ion and structural loss, may explain this phenomenon. CONCLUSIONS: The experiment showed that assessing surface loss is essential in addition to hardness testing, particularly as certain experimental conditions may produce a false perception of tissue recovery despite the actual surface loss. By analyzing the response of ostrich eggshell specimens to erosive challenges, researchers were able to identify an "overlooked" reduction in hardness in enamel specimens. The differences in the structure, chemical composition, and biological response to erosion in the presence of artificial saliva between enamel and ostrich eggshell could explain their distinct behaviors.

Micro-Raman spectroscopy analysis of dentin remineralization using eggshell derived nanohydroxyapatite combined with phytosphingosine.

The aim of this study was to assess the remineralization efficacy of chicken eggshell-derived nano-hydroxyapatite (CEnHAp) combined with phytosphingosine (PHS) on artificially induced dentinal lesions. PHS was commercially procured whereas CEnHAp was synthesized using microwave-irradiation method and characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), high-resolution scanning electron microscopy-energy-dispersive X-ray spectroscopy (HRSEM-EDX), and transmission electron microscopy (TEM). A total of 75 pre-demineralized coronal dentin specimens were randomly treated with one of the following test agents (n = 15 each): artificial saliva (AS), casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), CEnHAp, PHS, and CEnHAp-PHS under pH cycling for 7, 14, and 28 days. Vickers microhardness indenter, HRSEM-EDX, and micro-Raman spectroscopy methods were used to assess the mineral changes in the treated dentin samples. Data were submitted to Kruskal-Wallis and Friedman's two-way analyses of variance (p < 0.05). HRSEM and TEM analysis depicted irregular spherical structure of the prepared CEnHAp with a particle size of 20-50 nm. The EDX analysis confirmed the presence of Ca, P, Na and Mg ions. The XRD pattern showed the characteristic crystalline peaks for hydroxyapatite and calcium carbonate that are present in the prepared CEnHAp. Dentin treated with CEnHAp-PHS revealed highest microhardness values along with complete tubular occlusion compared to other groups at all test time intervals (p < 0.05). Specimens treated with CEnHAp showed increased remineralization than those treated with CPP-ACP followed by PHS and AS groups. The intensity of mineral peaks, as observed in the EDX and micro-Raman spectra, confirmed these findings. Further, the molecular conformation of the collagen's polypeptide chains, and amide-I and CH2 peaks attained peak intensities in dentin treated with CEnHAp-PHS and PHS whereas other groups revealed poor stability of collagen bands. Microhardness, surface topography, and micro-Raman spectroscopy analyses revealed that dentin treated with CEnHAp-PHS have an improved collagen structure and stability as well as highest mineralization and crystallinity.

A novel microfluidic compact disc to investigate electrochemical property changes between artificial and real salivary samples mixed with mouthwashes using electrical impedance analysis.

Diagnosing oral diseases at an early stage may lead to better preventive treatments, thus reducing treatment burden and costs. This paper introduces a systematic design of a microfluidic compact disc (CD) consisting of six unique chambers that run simultaneously from sample loading, holding, mixing and analysis. In this study, the electrochemical property changes between real saliva and artificial saliva mixed with three different types of mouthwashes (i.e. chlorhexidine-, fluoride- and essential oil (Listerine)-based mouthwashes) were investigated using electrical impedance analysis. Given the diversity and complexity of patient's salivary samples, we investigated the electrochemical impedance property of healthy real saliva mixed with different types of mouthwashes to understand the different electrochemical property which could be a foundation for diagnosis and monitoring of oral diseases. On the other hand, electrochemical impedance property of artificial saliva, a commonly used moisturizing agent and lubricant for the treatment of xerostomia or dry mouth syndrome was also studied. The findings indicate that artificial saliva and fluoride-based mouthwash showed higher conductance values compared to real saliva and two other different types of mouthwashes. The ability of our new microfluidic CD platform to perform multiplex processes and detection of electrochemical property of different types of saliva and mouthwashes is a fundamental concept for future research on salivary theranostics using point-of-care microfluidic CD platform.

An in vitro examination of fluoride ions release from selected materials - resin-modified glass-ionomer cement (Vitremer) and nanohybrid composite material (Tetric EvoCeram).

The aim of this study was to examine a short-term fluoride ions release from selected materials - resin-modified glass ionomer -Vitremer (3M ESPE) and nanohybrid universal composite - Tetric EvoCeram (IvoclarVivadent). Release of fluoride ions [µg/mm2 /h] from Tetric EvoCeram and Vitremer into nine environments (artificial saliva - AS, deionized water and 0.9% NaCl) differing in composition of the solution and pH was determined. Six samples were prepared for each solution. In the short-term study, the measurements were taken after 1, 3, 24, 48, 72 and 168 hours. The cumulative values as well as levels of fluoride ions released at concrete time intervals were compared. Within 7 days (168 hours), both materials showed variable levels of fluoride ions release. The highest value of fluoride ions release from nanohybrid Tetric EvoCeram material was reported in deionized water (8) after 24 hours (1.550 ± 0.014 [µg/mm2/h]) and the lowest value was read in the artificial saliva AS pH 7.5 (5) after 1 hour (0.022 ± 0.001 [µg/mm2/h]). What's more, the highest value of F- release from Vitremer was found in deionized water (8) after 168 hours of immersion (24.021 ± 2.280 [µg/mm2/h]) and the lowest value was in the artificial saliva AS (without Ca2+) pH 4.5 (6) (0.303 ± 0.249 [µg/mm2/h]) after 168 hours. Cumulated release of F- after 7 days was notably higher from resin- modified glass ionomer material - Vitremer in all artificial saliva solutions (1-7) which imitated the environment of oral cavity. Therefore, we can assume that Vitremer has better remineralization potential and it may constitute a more effective method of tooth decay prevention.

Chemical-physical characteristics of artificial saliva substitutes: rheological evaluation.

OBJECTIVE: We aimed at evaluating some chemical-physical properties of artificial saliva substitutes easily available on the E.U. market, such as viscosity, pH, buffering capacity, superficial tension, density and spinnbarkeit and to compare the results with human natural saliva bibliographic data. MATERIALS AND METHODS: Based on the easy availability on the market, twelve artificial saliva solutions in liquid formulation were analyzed. Kinematic viscosity (cSt) was determined using a micro-Ubbelohde model capillary viscosimeter (ViscoClock, SCHOOT-GERATE Mainz, Germany). Dynamic viscosity (mPas) was determined, through a simple multiplication between density (g/cm3) and kinematic viscosity of each solution. pH analyses were carried out at room temperature using a pH-meter (Mettler Toledo®- Five Easy, Columbus, OH, USA). Spinnbarkeit analysis was performed by a self-owned instrument built for the purpose. RESULTS: The median density value, obtained from the cohort of artificial saliva substitutes, was 1.036 g/cm3. The median value of the kinematic viscosity was 8.984 cSt. The median spinnbarkeit value was 3.2 mm and the median pH value was 6.29. In this study we found an almost linear correlation between the kinematic viscosity and spinnbarkeit values of the artificial saliva substitutes evaluated. CONCLUSIONS: Saliva substitutes should be as faithful as possible to the characteristics of human saliva, in order to completely replace its functions in the oral cavity. Nevertheless, despite several R&D efforts, it is difficult to reproduce all the different features that belongs to natural saliva in one device. Therefore, it would be desirable to create more products reproducing saliva with various rheological characteristics in respect of the main salivary functions such as: chewing, speaking and tissue coating.

Adsorption of Candida albicans on Ti-6Al-4V surface and its corrosion effects in artificial saliva.

In this study, the corrosion behavior and mechanism of Ti-6Al-4V in artificial saliva with Candida albicans were investigated using electrochemical and surface analysis techniques. Fluorescence microscopy (FM) and confocal laser scanning microscopy (CLSM) showed that C. albicans could easily adsorb on the surface of Ti-6Al-4V alloy to form non-dense biofilm. The non-compact biofilm provided necessary conditions for pitting corrosion on Ti-6Al-4V alloys by scanning electron microscopy (SEM) observation. The potentiodynamic polarization (PDP) curves and electrochemical impedance spectroscopy (EIS) revealed that C. albicans significantly reduced the corrosion resistance of Ti-6Al-4V alloys. The cyclic voltammetry (CV) and differential pulse voltammetry (DPV) results indicated that C. albicans biofilm promoted electron transfer from the anodic sites to cathodic depolarizer during the corrosion process, showing that the role of oral fungi must be considered when evaluating the performance of oral materials. This study may provide a new clue for evaluating the corrosion resistance of dental implant materials in the oral environment.