Yasmine Mendes Pupo

An innovative quaternary ammonium methacrylate polymer can provide improved antimicrobial properties for a dental adhesive system.

A quaternary ammonium methacrylate polymer (QAMP) with antimicrobial potential was synthesized. The resulting product (QAMP) was characterized by FTIR spectroscopy, NMR spectroscopy, visible spectrophotometry, XRPD and TGA. The in vitro susceptibility tests against Streptococcus mutans of QAMP were investigated prior and after incorporation into a commercial adhesive system (Clearfil™ SE Bond). The release of quaternary ammonium compounds from the experimental adhesive system (Clearfil™ SE Bond + 5% QAMP) was performed during 1, 7, 14, 21 and 30 days. Spectroscopic data confirmed that QAMP was successfully obtained. Thermogravimetric analysis indicated that QAMP was heat stable. Prior incorporation into the adhesive system, QAMP revealed an inhibition halo of 18.33 ± 0.6 mm. By agar disk diffusion test, Clearfil™ SE Bond containing 5% QAMP presented an inhibition halo (16.67 ± 1.5 mm) similar to Clearfil™ Protect Bond (positive control, 17.00 ± 1.7, p = 0.815) and significantly higher than Clearfil™ SE Bond (negative control, 11.00 ± 1.0, p = 0.006). The minimum inhibitory/bactericidal concentrations for Clearfil™ SE Bond containing 5% QAMP were 20 μL mL−1. The release of quaternary ammonium compounds from the experimental adhesive containing QAMP was very low (5.1%) when compared to Clearfil™ Protect Bond that released 47.2% of its quaternary ammonium monomer (MDPB) after 30 days. The QAMP can offer enhanced antimicrobial properties for self-etching adhesive systems.

Effect of a Novel Quaternary Ammonium Methacrylate Polymer (QAMP) on Adhesion and Antibacterial Properties of Dental Adhesives

This study investigated the resin–dentin bond strength (μTBS), degree of conversion (DC), and antibacterial potential of an innovative adhesive system containing a quaternary ammonium methacrylate polymer (QAMP) using in situ and in vitro assays. Forty-two human third molars were flattened until the dentin was exposed and were randomly distributed into three groups of self-etching adhesive systems: Clearfil™ SE Bond containing 5% QAMP (experimental group), Clearfil™ Protect Bond (positive control) and Clearfil™ SE Bond (negative control). After light curing, three 1 mm-increments of composite resin were bonded to each dentin surface. A total of thirty of these bonded teeth (10 teeth per group) was sectioned to obtain stick-shaped specimens and tested under tensile stress immediately, and after 6 and 12 months of storage in distilled water. Twelve bonded teeth (4 teeth per group) were longitudinally sectioned in a mesio-to-distal direction to obtain resin-bonded dentin slabs. In situ DC was evaluated by micro-Raman spectroscopy. In vitro DC of thin films of each adhesive system was measured using Fourier transform infrared spectroscopy. In vitro susceptibility tests of these three adhesive systems were performed by the minimum inhibitory/minimum bactericidal concentration (MIC/MBC) assays against Streptococcus mutans, Lactobacillus casei, and Actinomyces naeslundii. No statistically significant difference in μTBS was observed between Clearfil™ SE Bond containing 5% QAMP and Clearfil™ SE Bond (p > 0.05) immediately, and after 6 and 12 months of water storage. However Clearfil™ Protect Bond showed a significant reduction of μTBS after 12 months of storage (p = 0.039). In addition, QAMP provided no significant change in DC after incorporating into Clearfil™ SE Bond (p > 0.05). Clearfil™ SE Bond containing 5% QAMP demonstrated MIC/MBC values similar to the positive control against L. casei and A. naeslundii and higher than the negative control for all evaluated bacterial strains. The use of QAMP in an adhesive system demonstrated effective bond strength, a suitable degree of conversion, and adequate antibacterial effects against oral bacteria, and may be useful as a new approach to provide long-lasting results for dental adhesives.

Effect of the regional variability of dentinal substrate and modes of application of adhesive systems on the mechanical properties of the adhesive layer

Aim: This study assessed the effect of the dentin depth and the application mode on the hardness and elastic modulus of the adhesive layer. Materials and Methods: Occlusal surfaces of 48 caries-free human third molars were removed, at two levels: Superficial and deep dentin. For each type of surface, the test specimens were randomly divided into groups which underwent the application: A conventional two-step adhesive system (Adper™ Single Bond [SB]) and self-etch adhesives system (Adper™ SE Plus [SE] and AdheSE® [AD]). The adhesives applied were active or passive. Composite build-ups were constructed incrementally. The teeth were sectioned, embedded, and polished. The nanoindentation test was performed in the adhesive layer. The results were analyzed by ANOVA and Tukey tests. Results: In the adhesive layer, the higher hardness (0.307 ± 0.006 GPa) and elastic modulus (4.796 ± 0.165 GPa) of SE were obtained in superficial dentin in passive application. The elastic modulus of SE (4.115 ± 0.098 GPa) was lowest in active application in superficial dentin. The active application significantly increased the hardness of the SB in the deep dentin (0.011 ± 0.314 GPa) compared the superficial dentin (0.280 ± 0.010 GPa). For the AD, only the mode of application was statistically significant (P=0.0041) for the hardness, active application (0.289 ± 0.015 GPa) being higher than passive application (0.261 ± 0.013 GPa) (P=0.0042) in deep dentin. Conclusion: The experimental results reveal that the mechanical properties were influenced for the application mode of adhesive systems and dentin depth.

A Stability-Indicating HPLC-DAD Method for Determination of Ferulic Acid into Microparticles: Development, Validation, Forced Degradation, and Encapsulation Efficiency

A simple stability-indicating HPLC-DAD method was validated for the determination of ferulic acid (FA) in polymeric microparticles. Chromatographic conditions consisted of a RP C18 column (250 mm × 4.60 mm, 5 μm, 110 Å) using a mixture of methanol and water pH 3.0 (48 : 52 v/v) as mobile phase at a flow rate of 1.0 mL/min with UV detection at 320 nm. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of quantification, limit of detection, accuracy, precision, and robustness provided suitable results regarding all parameters investigated. The calibration curve was linear in the concentration range of 10.0–70.0 μg/mL with a correlation coefficient >0.999. Precision (intraday and interday) was demonstrated by a relative standard deviation lower than 2.0%. Accuracy was assessed by the recovery test of FA from polymeric microparticles (99.02% to 100.73%). Specificity showed no interference from the components of polymeric microparticles or from the degradation products derived from acidic, basic, and photolytic conditions. In conclusion, the method is suitable to be applied to assay FA as bulk drug and into polymeric microparticles and can be used for studying its stability and degradation kinetics.

Influence of different resin cements and surface treatments on microshear bond strength of zirconia-based ceramics

Aim: This study aims to evaluate the microshear bond strength of zirconia-based ceramics with different resin cement systems and surface treatments. Materials and Methods: Forty blocks of zirconia-based ceramic were prepared and embedded in polyvinyl chloride (PVC) tubes with acrylic resin. After polishing, the samples were washed in an ultrasonic bath and dried in an oven for 10 min. Half of the samples were subjected to sandblasting with aluminum oxide. Blocks were divided into four groups (n = 10) in which two resin cements were used as follows: (1) RelyX™ U100 with surface-polished zirconia; (2) RelyX™ U100 with surface-blasted zirconia; (3) Multilink with surface-polished zirconia; and 4) Multilink with surface-blasted zirconia. After performing these surface treatments, translucent tubes (n = 30 per group) were placed on the zirconia specimens, and resin cement was injected into them and light cured. The PVC tubes were adapted in a universal testing machine; a stiletto blade, which was bolted to the machine, was positioned on the cementation interface. The microshear test was performed at a speed of 0.5 mm/min. Failure mode was analyzed in an optical microscope and classified as adhesive, cohesive, or mixed. Results: The null hypothesis of this study was rejected because there was a difference found between the resin cement and the surface treatment. There was a statistical difference (P < 0.005) in RelyX™ U100 with surface-blasted zirconia, in relation to the other three groups. For Multilink groups, there was no statistical difference between them. Conclusion: Self-adhesive resin cement showed a more significant tendency toward bond strength in the ceramic-based zirconium oxide grit-blasted surfaces.

Cytotoxicity of Etch-and-Rinse, Self-Etch, and Universal Dental Adhesive Systems in Fibroblast Cell Line 3T3

The aim of this study was to evaluate in fibroblast cultures the direct cytotoxic effects of etch-and-rinse, self-etch, and universal adhesive systems. The sterile glass cover slips (n = 3) were then immersed in culture medium to obtain the eluates for the experimental groups: (1) Adper™ Single Bond 2; (2) Ambar; (3) Adper™ Scotchbond™ Multi-Purpose; (4) Scotchbond™ Universal; (5) Ambar Universal; and (6) OptiBond All-In-One. As a negative control, sterile glass cover slips were immersed in culture medium only. After 24 h, the eluate obtained was applied on fibroblast culture. Cell viability and cell morphology were evaluated by MTT assay and SEM, respectively. Data were analyzed by Kruskal–Wallis and Mann–Whitney tests (α = 0.05). All adhesive systems except universal reduced cell viability in 3T3 cells to between 26.04% and 56.57%, and Scotchbond Universal and Ambar Universal reduced cell viability to 2.13% and 3.57%, respectively, when compared to the negative control. Cytoplasmic membrane shrinkage and cell-free areas with residual membrane fragments from dead cells were observed. In conclusion, improvements in universal adhesive system formulations and their mechanisms of action are not accompanied by increased toxicity compared with those in other systems, warranting commitment to the use of these dentin-pulp complexes.

Effect on vascular permeability of a self-etching adhesive system containing an antimicrobial quaternary ammonium polymer QAMP into subcutaneous tissue of rats

OBJECTIVE This study investigated the effect of a self-etching adhesive system containing an antimicrobial quaternary ammonium methacrylate polymer (QAMP) on the vascular permeability using Evans blue and laser-Doppler flowmetric methods. DESIGN Forty rats were anesthetized and divided into groups: saline solution; Clearfil™ Protect Bond; Clearfil™ SE Bond; Clearfil™ SE Bond containing QAMP. Injections of Evans blue were administrated intravenously and the substances were injected intradermally. Immediately before injection and after 3 and 6h, was evaluated the blood flow. The animals were killed 3 and 6h after injection. The dorsal skin was dissected and experimental sites were obtained. The vascular permeability was evaluated by dye extravasation area, the dye was extracted and absorbance measured. RESULTS Concerning the Evans blue method, Clearfil™ SE Bond containing QAMP showed an extravasation area statistically similar to Clearfil™ SE Bond and lower than Clearfil™ Protect Bond. No statistical difference was verified among experimental groups for the amount of dye extracted. Clearfil™ SE Bond containing QAMP provided better laser-Doppler flowmetric parameters than Clearfil™ Protect Bond immediately and 3h after injection. CONCLUSION The QAMP had lower effect on the exudative phase of the inflammatory process.

Prevalence of degenerative joint disease of the temporomandibular joint: a systematic review

ObjectivesThe purpose of this systematic review was to evaluate evidence about the prevalence of degenerative joint disease (DJD) of the temporomandibular joints (TMJ).Materials and methodsWe performed search on electronic databases and gray literature from their inception to January 2018. Studies reporting prevalence data of DJD on TMJ were included. DJD was assessed through clinical and imaging diagnosis. Studies risk of bias was evaluated using the Critical Appraisal Checklist for Studies Reporting Prevalence Data.ResultsFrom 1082 studies, 32 were identified, and the sample size included 3435 subjects. They were clustered into two groups: the first comprised studies that reported prevalence of DJD in TMJ secondary to rheumatic systemic diseases like juvenile idiopathic arthritis (JIA) and rheumatoid arthritis (RA) and the second group comprised studies that reported prevalence of DJD on temporomandibular disorder patients. The prevalence of DJD on JIA patients ranged from 40.42% (n = 47) to 93.33% (n = 15) and on RA patients from 45.00% (n = 20) to 92.85% (n = 56). Among TMD patients, the prevalence of DJD reported according to patients ranged from 18.01% (n = 1038) to 84.74% (n = 118) and reported according to joints ranged from 17.97% (n = 178) to 77.23% (n = 224).ConclusionThis review attempts to high prevalence of DJD in patients with systemic rheumatic disease and a less prevalent, but still high, occurrence in patients with TMD without systemic involvement.Clinical relevanceSpecialist doctors and dentists should be alert to not underestimate and to correctly diagnose DJD of the TMJ early in patients with rheumatic disease and TMD.

Morphology of root canal surface: A reflection on the process of cementation of the composite relined glass fiber post

Background: The present study was conducted to evaluate the bond strength in the different root thirds (premolars and maxillary central incisors) of composite relined glass fiber posts compared to untreated glass fiber posts cemented with dual- or chemical-cure cements. Materials and Methods: Sixty human single-rooted premolars (flat canal) (n = 15) and 12 maxillary central incisors were used (round canal) (n = 3). The teeth were sectioned, and the roots received endodontic treatment. The standardized preparation of the canals was carried out, and the roots were randomly divided into four groups according to the cementation systems: G1: cemented posts (dual: Ambar/Allcem); G2: relined posts (dual: Ambar/Allcem); G3: cemented posts (chemical: Fusion Duralink/Cement Post); and G4: relined posts (chemical: Fusion Duralink/Cement Post). The roots were cut to give two slices of each third of the root canal per specimen. Push-out test was conducted at a speed of 0.5 mm/min. Data were analyzed by analysis of variance and Tukeys post hoc test (α = 0.05). Results: There was no statistically significant difference between groups for the premolars (flat canal) (P = 0.959). There was a significant difference in the central incisors between the middle and apical thirds in the cemented group when using the dual system (P = 0.04) and between the middle and apical thirds (P = 0.003) and cervical and apical thirds (P = 0.033) when using the chemical system. Conclusion: Due to the anatomy of the root canal, flat canal of the premolars does not require relining, but round canal of the maxillary central incisors demands it for more secure in the bond strength.

Avaliação da liberação de flúor e da capacidade de recarga em diferentes cimentos de ionômero de vidro

Objective To evaluated the ability to fluoride release and recharge in the different glass ionomer cements during simulation of cariogenic challenge. Material and method Twelve samples were made for each experimental group: conventional glass ionomer cements, Maxxion R (FGM), Ketac Molar EasyMix (3M ESPE); resin modified glass ionomer cement, Vitrebond (3M ESPE); and composite resin Filtek™ Z350XT (3M ESPE), negative control. The samples were immersed alternately in pH cycling method, remaining 6 hours in demineralization solution and 18 hours in remineralization solution and maintained at 37 °C. Fluoride release was measured 1, 2, 7, and 14 days before and after recharging with specific electrode coupled to the analyzer apparatus pH/fluoride, each measurement with calibrated solutions of sodium fluoride to 1 and 10 ppm, prepared with TISAB II. For reading was added 0.5 mL of sample to an equal volume of TISAB II. Recharging was made with neutral sodium fluoride to 2% for 4 minutes in the samples, washed and again immersed pH cycling solutions. Data were subjected to two-way ANOVA and Tukey’s post-hoc test (α = 0.05). Result The initial fluoride release (μgF/cm2) was 45.36 ; 37.49 and 26.35 for Maxxion R, Vitrebond and Ketac Molar EasyMix, respectively. Significant differences between the materials before and after recharging were observed (p=0.001). After topical application of fluoride, both showed ability to recharge. Conclusion The glass ionomer cements evaluated were capable of releasing fluoride in pH cycling solutions and may recharge through of a topical application.