Effect of Graphene Oxide Nanoparticles Incorporation on the Mechanical Properties of a Resin-Modified Glass Ionomer Cement.

The objective of this study was to evaluate the effect of incorporating different concentrations of graphene oxide (GO) nanoparticles on the mechanical properties of a resin-modified glass ionomer cement (RMGIC). A commercial RMGIC (Resiglass R, Biodinâmica) was modified by incorporating 0.1% and 0.5% (by weight) of GO into the powder's material. An unmodified RMGIC was used as a control group. Powder samples were characterized using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). Specimens were fabricated and subjected to flexural strength (n = 15), modulus of elasticity (n = 15), Vicker's microhardness (n = 10), and surface roughness tests (n = 10). Data were analyzed using one-way ANOVA and Tukey's post hoc test (α = 5%). Experimental groups' powder demonstrated a homogeneous dispersion of GO. No statistically significant difference was observed in flexural strength (p = 0.067) and modulus of elasticity (p = 0.143) tests. The groups containing 0.1% and 0.5% GO showed significantly higher microhardness and lower surface roughness values (p < 0.001) compared to the control group. The incorporation of GO nanoparticles at concentrations of 0.1% and 0.5% improved the microhardness and surface roughness without negatively affecting the flexural strength and modulus of elasticity of an RMGIC.

Glass ionomer cement particles pre-reacted with chlorhexidine: Physical/chemical properties and antimicrobial activity.

OBJECTIVE: Analyze the effects of the functionalization of pre-functionalized GIC particles with chlorhexidine on the physicochemical properties and antimicrobial activity. MATERIALS AND METHODS: Four groups were prepared: (1) GIC (Bioglass R - Biodinamica) - control group; (2) GIC-CHX 1%: Group containing 1% pre-reacted CHX particles; (3) GIC-CHX 2.5%: Group containing 2.5% pre-reacted CHX particles; (4) GIC-CHX 5%: Group containing 5% pre-reacted CHX particles. Hourglass-shaped specimens (10 mm × 2 mm x 1 mm) were fabricated for mechanical tests including cohesive strength (n = 12), modulus of elasticity (n = 12) and microhardness (n = 10). Discs (10 mm × 2 mm) were prepared for the analysis of Ca+2, PO4- and F- ions release (n = 3), and roughness (n = 12). To evaluate the setting time, a Gilmore needle was used according to ISO 9917-1:2016. Disk-shaped specimens (5 × 1mm) were manufactured and subjected to bacterial activity (n = 9) (Streptococcus mutans ATCC 159). RESULTS: Modulus, roughness, setting time and ions release (Ca+2, PO4-, and F-) there were no statistically significant differences among the groups (p > 0.05). The setting time did not change with the incorporation of CHX. The GIC-CHX 2.5% and GIC-CHX 5% groups exhibited superior antibacterial activity compared to the control group and GIC-CHX 1% (p < 0.001). The GIC-CHX 5% group showed the highest microhardness values (p < 0.041), cohesive strength (p < 0.009) when compared to the control group. CONCLUSION: The pre-reacted CHX in GICs was able to confer antimicrobial activity, improve cohesive strength, microhardness, and did not impair ion release, setting time, and roughness.

Root Canal Dentin Microhardness after Contact with Antibiotic Medications: An In Vitro Study.

Background: Antibiotic pastes used as intracanal medication in cases of revascularization therapy might cause negative effects on tooth properties, such as a reduction in dentin microhardness. This in vitro study investigated dentin microhardness in three different locations distancing from the canal lumen after 20 days of treatment with a tri-antibiotic paste (ciprofloxacin, metronidazole, and minocycline), and with a double-antibiotic paste (ciprofloxacin and metronidazole), with calcium hydroxide [Ca(OH)2] UltracalTM XS-treated dentin as comparison. Material and Methods: Human mandibular premolars (n = 48) had the root canals cleaned and shaped and were used to produce dentin slices. Dentin slices remained immersed in the medications for 20 days. The Knoop microhardness (KHN) test was performed before (baseline/Day-0) and after treatment (Day-20) with the medications. Indentations were made at 25 µm, 50 µm, and 100 µm distances from the root canal lumen. The KHN was compared intra-group using Wilcoxon's test. Independent groups were compared using Mann-Whitney's and Kruskal-Wallis' tests, at α = 5%. Results: The microhardness in all the tested groups was reduced at Day-20 in comparison with Day-0 (p < 0.001) (intra-group comparison/same distances). The Day-0 values were similar, and the Day-20 values were higher for the Ca(OH)2 group (p < 0.05) (comparison between groups/same distances). Conclusions: Calcium hydroxide for 20 days would be preferred rather than antibiotic pastes to minimize the expected reduction in dentin microhardness during regenerative procedures.

Filling Material Bond Strength to Dentin Is Positively Influenced by the Agitation of Endodontic Final Irrigating Solutions.

Introduction: The final step of irrigation has been considered to of increase the bonding strength of filling material to dentin. This study investigated the impact of three final-step irrigation methods on the endodontic sealer bond strength to dentin by using a micro push-out test. Materials and Methods: Palatal roots of human maxillary molars were cleaned and shaped and randomly divided in six groups (n=15) according to the final-step irrigation method and the type of root canal sealer used. The solutions used for the final-step irrigation were 17% ethylenediaminetetraacetic acid and 2.5% sodium hypochlorite, which underwent three methods: 1) syringe-needle irrigation/conventional, 2) passive ultrasonic irrigation, and 3) XP-endo Finisher agitation. The root canal sealers used were: EndoSequence BC Sealer, and AH-Plus sealer. Roots were obturated with the single cone technique and then, cross-sectioned in 2-mm-thick slices (3 slices from each root). Push-out test was performed on the sliced specimens (cervical, middle, and apical thirds) with a universal testing machine. Bond strength values were recorded in megapascal (MPa). Subsequently, each specimen was longitudinally split to verify the type of failure. Data analysis was performed using Johnson transformation, three-way analysis of variance, Tukey's post-hoc tests, and the partial Eta squared test. Results: There were significant differences in bond strength between the sealers [AH: 4.46±2.24 and BC: 3.47±2.19 MPa (P<0.001)]; between final-step irrigation methods [passive ultrasonic irrigation: 4.52±2.25, XP-endo Finisher: 3.93±3.93 and syringe-needle irrigation/conventional: 3.37±2.51 MPa (P<0.001)], and between the root canal thirds represented by the sliced specimens [cervical: 5.45±2.39, middle: 4.14±1.99 and apical: 2.30±1.30 MPa (P<0.001)]. The interaction between the variables had no significance (P>0.05). Conclusion: Agitation of the final irrigating solution may improve the bonding of the sealer to canal walls. AH-Plus sealer had the highest bond strength. The bond strength reduced significantly towards the apical third.

Physicochemical and histological analysis of an experimental endodontic repair material containing 45S5 bioactive glass.

This study aimed to evaluate the maximum compressive strength, the modulus of elasticity, pH variation, ionic release, radiopacity and biological response of an experimental endodontic repair cement based on 45S5 Bioglass®. An in vitro and in vivo study with an experimental endodontic repair cement containing 45S5 bioactive glass was conducted. There were three endodontic repair cement groups: 45S5 bioactive glass-based (BioG), zinc oxide-based (ZnO), and mineral trioxide aggregate (MTA). In vitro tests were used to evaluate their physicochemical properties: compressive strength, modulus of elasticity, radiopacity, pH variation, and the ionic release of Ca+ and PO4. An animal model was used to evaluate the bone tissue response to endodontic repair cement. Statistical analysis included the unpaired t-test, one-way ANOVA and Tukey's test. BioG showed the lowest compressive strength and ZnO showed the highest radiopacity among the groups, respectively (p < 0.05). There were no significant differences in the modulus of elasticity among the groups. BioG and MTA maintained an alkaline pH during the 7 days of evaluation, both at pH 4 and in a pH 7 buffered solutions. PO4 was elevated in BioG, peaking at 7 days (p < 0.05). Histological analysis showed less intense inflammatory reactions and new bone formation in MTA. BioG showed inflammatory reactions that decreased over time. These findings suggest that the BioG experimental cement had good physicochemical characteristics and biocompatibility required for bioactive endodontic repair cement.

Apical Sealing and Bioactivity of an Experimental Gutta-Percha Containing Niobium Phosphate Bioglass.

This study evaluated the apical sealing ability and bioactivity of an experimental gutta-percha containing niobium phosphate bioglass. Thirty-six human premolars were endodontically prepared and divided into three groups: GPC-filling with conventional gutta-percha; GBC-filling with bioceramic gutta-percha (EndoSequence BC); GNB-filling with experimental gutta-percha containing niobophosphate. Teeth were stored in tubes containing 2 mL of simulated body fluid (SBF) solution in an oven for 30 days. Then, the samples were immersed in lanthanum nitrate solution and analyzed for apical nanoleakage (NI) with a scanning electron microscope (SEM/EDS) and transmission electron microscope (TEM). Gutta-percha specimens were immersed for 28 days (SBF) and analyzed in SEM/EDS and X-ray diffraction (XRD) to assess bioactivity. NI data originated from the SEM/EDS were analyzed using the Kruskal-Wallis test (α = 5%). NI data originated from TEM and bioactivity were descriptively reported. Statistical analysis did not detect a significant difference between groups (p = 0.13) for NI. In the bioactivity analysis, an abundant layer of hydroxyapatite was identified only in the surface of the GNB group samples. The gutta-percha containing niobophosphate bioglass promoted an apical sealing similar to EndoSequence BC, in addition to demonstrating bioactivity through the deposition of hydroxyapatite on the surface of the material after immersion in SBF.

Effect of Bioactive Filler Addition on the Mechanical and Biological Properties of Resin-Modified Glass Ionomer.

The maintenance of affected dentin can promote the greater conservation of tooth structure. The development of materials that have properties capable of reducing the demineralizing potential and/or even helping in dental remineralization is important for conservative dentistry. This study aimed to evaluate, in vitro, the alkalizing potential, fluoride as well as calcium ion release ability, antimicrobial activity, and dentin remineralization properties of resin-modified glass ionomer cement (RMGIC) incorporated with a bioactive filler (niobium phosphate (NbG) and bioglass (45S5)). The study samples were grouped into RMGIC, NbG, and 45S5. The materials' alkalizing potential, ability to release calcium as well as fluoride ions, and antimicrobial properties concerning Streptococcus mutans UA159 biofilms were analyzed. The remineralization potential was evaluated using the Knoop microhardness test, which was performed at different depths. The alkalizing and fluoride release potential was higher for the 45S5 group (p < 0.001) over time. An increase in the microhardness of demineralized dentin was observed in the 45S5 and NbG groups (p < 0.001). No differences in biofilm formation were observed between the bioactive materials, although 45S5 exhibited lower biofilm acidogenicity at different time points (p < 0.001) and greater calcium ion release in the microbial environment. A resin-modified glass ionomer cement enriched with bioactive glasses, particularly 45S5, is a promising alternative for the treatment of demineralized dentin.

Effect of preheating on the physicochemical properties and bond strength of composite resins utilized as dental cements: An in vitro study.

STATEMENT OF PROBLEM: Little is known regarding the use of preheated composite resins to bond indirect restorations and its impact on mechanical properties when compared with resin cements. PURPOSE: The purpose of this in vitro study was to compare the chemical and physical properties and bond strength to enamel and ceramics of preheated composite resins and resin cements. MATERIAL AND METHODS: Two composite resins, the microhybrid Filtek Z250XT and the nanoparticulate Z350XT were tested, and 2 commercially available resin cements, the dual-polymerized Rely-X ARC and the light-polymerized Rely-X Veneer were used as controls. A device (HotSet) was used to preheat the composite resins to 69 °C before light-polymerization. The following properties were tested: flexural strength, modulus of elasticity, fracture toughness, microshear bond strength to enamel and ceramics, degree of conversion, flow, sorption and solubility, and color stability. Statistical analysis was done with ANOVA and Holm-Sidak for multiple comparisons (α=.05). RESULTS: Preheating had no significant effect on the degree of conversion, flexural strength, fracture toughness, solubility, or microshear bond strength to the enamel of the tested composite resins (P>.05). However, preheating increased the sorption and reduced the microshear bond strength to the ceramic (P<.05). The flowability of the composite resins increased with heating but showed lower values when compared with both resin cements (P<.05). Color stability was more affected in the preheated composite resins than in the resin cements. CONCLUSIONS: The preheating process resulted in little to no benefit in the evaluated properties for the composite resins. Resin cements appear to be the best option for cementing indirect restorations.

Resin-modified glass ionomer enriched with BIOGLASS: Ion-release, bioactivity and antibacterial effect.

Developing dental materials for the prevention of remineralization or demineralization is important for high-risk caries patients. This study aimed to evaluate the physicochemical and microbiological effects of adding 45S5 bioglass to resin-modified glass ionomer cement (RMGIC). Samples belonged to the following groups: GIC: conventional glass ionomer cement (Vitro Fil), RMGIC: resin-modified GIC (Vitro Fil LC), and RMGIC/45S5: RMGIC with 10% (wt %) of 45S5. Changes in pH and release of fluoride, calcium, and phosphorus ions under acidic (pH 4) and neutral (pH 7) pH conditions were evaluated. Antibacterial activity was verified based on colony-forming units. Material sorption and solubility were analyzed after bacterial exposure. After 28 days, the bioactivity of the materials was evaluated using scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Analysis of variance, post hoc Scheffe, and Tukey (α = 0.05) tests were employed for statistical analysis. RMGIC/45S5 showed higher alkalization activity, calcium release at pH 4 and 7, and sorption than GIC and RMGIC (p < .05). Release of phosphorus and fluoride at pH 4 and 7 was higher for GIC than that for RMGIC and RMGIC/45S5 (p < .05). RMGIC/45S5 showed higher values than RMGIC (p < .05). However, antibacterial activity did not differ among the groups. Precipitates of calcium and phosphorus were visualized in RMGIC/45S5 samples via SEM/EDS. These results indicate that the RMGIC/45S5 promotes alkalization and increases the release of calcium, phosphorus, and fluoride ions, resulting in precipitate deposition rich in calcium and phosphorus, thereby being a promising option to improve the bioactivity of RMGIC.

Physicochemical, Mechanical, and Esthetic Properties of the Composite Resin Manipulated with Glove Powder and Adhesive as a Modeling Liquid.

Composite resins with low flowability are usually handled and manipulated before insertion into the tooth preparation with gloved hands and/or using an instrument covered with a little amount of adhesive to facilitate modeling. We investigated if the modeling techniques (combined or not) affected physicochemical and esthetic properties of a composite resin. Specimens were fabricated and divided into groups according to the handling/modeling technique: Gloved-hands (composite was hand-manipulated with powdered latex gloves); Adhesive (adhesive was used in between the composite layers); Gloved-hands + Adhesive; Control (no adhesive and no touch with gloved-hands). The highest values for flexural strength (MPa), modulus of elasticity (GPa), and fracture toughness (MPa.m0.5) were obtained for Adhesive and Gloved-hands + Adhesive (p < 0.05); the lowest values were obtained for Control and Gloved-hands (p < 0.05). The Control group had the highest sorption. The Gloved-hands (p < 0.05) group had the highest solubility. Adhesive and Gloved-hands + Adhesive had a similar solubility (p > 0.05). The Control group (p < 0.05) had the lowest solubility. There was no statistical interaction between translucency vs. handling/modeling techniques and color stability vs. handling/modeling techniques. Adhesive as a modeling liquid protected the composite against sorption and solubility (if powdered gloves were used) and improved its physical/mechanical properties. Translucency and color stability were not correlated with modeling techniques.

Does the Application of Additional Hydrophobic Resin to Universal Adhesives Increase Bonding Longevity of Eroded Dentin?

This paper evaluates the effect of an additional hydrophobic resin coat (extra HL) associated with universal adhesives on sound and eroded dentin and evaluated immediately or after 2 years of water storage to improve the microtensile bond strength (µTBS) and nanoleakage (NL) when compared to the use of universal adhesives only. Sixty-four molars were assigned to eight groups using the following combinations: 1. dentin substrate, including sound and eroded dentin; 2. treatment, including the control and extra HL and storage time (immediately and after two-years of storage). Two universal adhesives (Prime & Bond Active or Scotchbond Universal) were evaluated. Before restoration, half of the teeth were subjected to soft-drink erosion. Composite buildups were bonded; specimens were stored (37 °C/24 h), sectioned into resin−dentin bonded sticks and tested for microtensile bond strength and nanoleakage using SEM (immediately and after two-years of storage). Three-way ANOVA and Tukey's test (α = 0.05%) were used. In the immediate testing, the application of extra HL did not increase microtensile bond strength values compared with the control group in either substrate (p > 0.05). However, extra HL significantly decreased nanoleakage values when applied to eroded and sound dentin (p = 0.0001). After two years, the application of extra HL produced significantly higher microtensile bond strength and lower nanoleakage values than the control group for both adhesives (p = 0.0001). In all cases, sound dentin showed higher microtensile bond strength and lower nanoleakage values than eroded dentin (p = 0.000001). An extra HL increased the bond strength and reduced nanoleakage in eroded dentin after two-years of storage.

Postoperative Pain Following Root Canal Instrumentation Using ProTaper Next or Reciproc in Asymptomatic Molars: A Randomized Controlled Single-Blind Clinical Trial.

Aim: The development of postoperative pain following root canal instrumentation may impair patient's comfort and undermine their trust in the dentist. This study assessed the effect of root canal instrumentation techniques (rotary (PTN; ProTaper Next®) and reciprocating (R; Reciproc®)) on the postoperative pain intensity (primary outcome) and tenderness on biting (secondary outcome) of patients' asymptomatic molars. Methodology: This study protocol was registered with ReBec-WHO (U1111-1182-2800). From a pool of 112 patients evaluated for eligibility (healthy adults (≤18 years old)), with a single asymptomatic molar (maxillary or mandibular) indicated for root canal treatment, diagnosed with asymptomatic irreversible pulpitis (including chronic hyperplastic pulpitis), 75 were randomly allocated in similar proportions to receive the intervention (two-appointment root canal therapy) in either the PTN or R group. The allocated procedures were performed using standardized protocols. Participants (blinded to the instrumentation technique) rated their pain intensity at 6, 12 and 24 h and from day 2 to day 7 following the root canal instrumentation appointment using a VAS and an NRS; the ibuprofen tablets taken and the presence of tenderness on biting were recorded. The instrumentation time was registered. Univariate and multivariate statistics measured the effect of independent variables on the outcomes. Results: From the 75 patients allocated, 8 patients (4 from each group) were lost; in total, 33 patients were analyzed in the PTN group and 34 in the R group. The frequencies of postoperative pain (p > 0.05) and tenderness on biting (p > 0.05) were similar between groups. The medication intake (mean of 1.31 tablets) and the time of instrumentation (approximately 11 min) were similar between groups. Conclusion: ProTaper Next and Reciproc® caused a slight risk of tenderness on biting and contributed to similar self-reported postoperative pain (low intensity) up to 7 days following root canal shaping.

Experimental pastes containing niobophosphate and 45S5 bioactive glasses for treatment of dentin hypersensitivity: dentin permeability and tubule obliteration.

OBJECTIVES: This study tested the ability of bioactive pastes containing niobophosphate and 45S5 glasses to reduce dentin permeability and to obliterate dentinal tubules, as a mean of reducing human dentin hypersensitivity. MATERIALS AND METHODS: Experimental pastes with concentrations of 10, 20, and 30 wt% of two bioactive glasses (45S5 or niobophosphate [NbG]) were formulated. A paste without bioactive glass (placebo) and a commercial paste (Nano P, FGM) were used as controls. Forty dentin disc specimens were obtained from caries-free extracted third human molars and divided in 8 groups (n = 5). Percentage of permeability (%Lp) was assessed in a dental permeability machine considering hydraulic conductance, immediately after pastes application and at day 7, day 14, and day 21. The precipitates formed on the surface of the dentin discs (and dentinal tubules) were analyzed by SEM/EDS and micro-Raman spectra. Data of dentin permeability (%) 2-way repeated-measures (ANOVA) and Holm-Sidak post-tests (α = 0.05). Dentinal tubule obliteration was visually (and elemental) evaluated and descriptively reported. RESULTS: The experimental bioactive glass pastes containing NbG and 45S5, regardless of the concentration, reduced dentin permeability in comparison with pastes without bioactive glasses (P < 0.05). The formulated placebo and commercial paste did not reduce permeability over time (P < 0.05). SEM/EDS and micro-Raman analyses showed that both type of bioactive pastes (NbG or 45S5-based) presented mineral precipitates obliterating the dentinal tubules at day 21. NbG seems to offer a better initial effect than 45S5, while at 21 days there is no difference between both glasses. CONCLUSION: Experimental bioactive pastes containing NbG and 45S5 (at concentrations of 10%, 20%, or 30%) have potential to reduce dentin permeability (over time) in comparison with pastes without bioactive glasses; and this occurs on behalf of obliteration of dentinal tubules by microparticle and precipitate formation. CLINICAL RELEVANCE: Bioactive pastes containing NbG and 45S5 may benefit patients presenting dentin hypersensitivity, because these pastes can start acting fast after application and maintain their action up to 21 days.

Effect of an enamel matrix derivative (Emdogain) on the microhardness and chemical composition of human root dentin: an in vitro study.

The advantage of using an Enamel matrix derivative EMD Emdogain as an intracanal medication could be a manner to strength the tooth structure, improving the physical and chemical properties of dentin. We tested, in vitro, the effect of Emdogain on the surface microhardness and chemical composition of root dentin. Ten human teeth were used to produce dentin specimens originated from the canal walls (n = 30) that remained in contact to Emdogain gel for 90 days. Baseline and 90-days after Emdogain treatment measurements were performed using Fourier Transform Infrared Spectroscopy (ATR/FTIR), Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS) and Knoop indenters. The use of EMD (Emdogain) for 90 days in contact with human root canal dentin specimens did not alter the microhardness and morphology of dentin. The elemental structure of dentin was altered because there was a reduction in carbonate content.

Impact of Immersion Media on Physical Properties and Bioactivity of Epoxy Resin-Based and Bioceramic Endodontic Sealers.

This study assessed the effects of immersion media [distilled water (dw), phosphate buffered saline (pbs) and simulated body fluid (sbf)] in the physical properties [fluid uptake/sorption/solubility and alkalinization activity (pH)] and bioactivity of a bioceramic sealer: the BioRoot RCS (BioRoot) (Septodont). The epoxy-resin sealer AH Plus (Dentsply) was used as comparison. Sealers were immersed in dw, pbs and sbf to evaluate the fluid uptake/sorption/solubility and pH's media. Bioactivity was assessed with SEM/EDS, FTIR-ATR and XRD. BioRoot solubility was as follows: sbf > pbs = dw. BioRoot had alkaline pH, and AH Plus had neutral pH, regardless of the medium. BioRoot presented mineral precipitates and peaks indicating hydroxyapatite-precursors in pbs and sbf. AH Plus physical properties were not affected by immersion media and it had no bioactivity. pbs and sbf should be preferred to investigate bioceramic sealers over distilled water, because they were able to highlight the sealer properties. BioRoot maintained the alkaline environment and favored hard tissue deposition.

Synthesis and characterization of experimental endodontic sealers containing bioactive glasses particles of NbG or 45S5.

OBJECTIVE: This study evaluated the influence of adding bioactive glasses particles [Niobophosphate (NbG) or bioglass (45S5)] into endodontic cements in relation to physical, chemical and biological properties. METHODS: The following commercial cements were used as comparison: AH Plus (Dentsply), Endofill (Dentsply), MTA Fillapex (Angelus) and EndoSequence (BC Sealer, Brasseler). Setting time, radiopacity, flow rate, weight loss/variation, alkaline capacity (pH) at different time-intervals (24h/48h/7d/14d/28d), bioactivity (assessed under SEM/EDS, FTIR/ATR and XDR) and cell viability were measured. Data were analyzed by One-way ANOVA/Holm-Sidak post-test (α = 5%) (normal distribution) and Kruskal-Wallis/Students-Newman-Keuls post-test (α = 5%) (non-normal distribution). RESULTS: Bioactive endodontic experimental cements (containing NbG or 45S5) had high alkalinization capacity. The experimental cements presented high weight loss/variation (p < 0.001). 45S5 experimental cement did not present radiopacity (p < 0.001). AH Plus had the lowest cell cytotoxicity when compared to the other tested cements (p < 0.001). Regarding bioactivity, SEM/EDS analyses showed precipitates with high concentrations of Ca/P for 45S5 and NbG, as well as for MTA Fillapex and BC Sealer. AH plus and Endofill did not present bioactive precipitates. FTIR/ATR and XDR analyses found hydroxyapatite precursors for NbG, 45S5, MTA Fillapex and BC Sealer. SIGNIFICANCE: The incorporation of bioactive particles (NbG or 45S5) into endodontic cements had potential to neutralize acidic environments and induced formation of hydroxyapatite precursors. Clinically, these would produce a cement that is bactericidal and have the potential to improve tissue healing. The improved radiopacity and flowability would facilitate the visualization of the material in the radiograph and the filling of anatomical complexities during root canal obturation. As drawbacks, the excessive weight loss and post-setting cytotoxicity could result in clinical degradation of the cement and adjacent tissue irritation for the patient.

Development and characterization of experimental ZnO cement containing niobophosphate bioactive glass as filling temporary material.

AIMS: The aim of this study was to develop and characterize a temporary restorative material based on a zinc oxide matrix containing niobophosphate bioactive glass (NbG) for the caries-affected dentin treatment. MATERIAL AND METHODS: NbG was added to a ZnO2 matrix in different concentrations (wt%). EDS-SEM, ATR-FTIR and XRD analyses were performed to characterize the cement. Calcium release was evaluated in TRIS solution after 1, 7 and 14 days by colorimetric method (A650). Compressive strengths and setting times were performed to analyze mechanical properties. RESULTS: EDS spectra confirmed the presence of Ca, P and Nb in the groups containing NbG. EDS mapping exhibit the ZnO2 homogeneous distribution, and NbG immersed in this matrix. Peaks suggesting interaction between matrix and NbG were not detected in Ftir spectra. Calcium releasing showed to be time-dependent for experimental groups containing 10, 20, 30 and 40%. The NbG incorporation progressively increased the compressive strength values in the experimental groups. NbG incorporation seemed to influence the ZnO2 matrix early setting reaction. No statistical difference was observed in the final setting time. CONCLUSION: The addition of NbG particles into zinc oxide matrix could work as a mechanical reinforcement. It is suggested that the calcium released by the cement containing at least 10% NbG could induce apatite formation.

Bioactive toothpastes in dentin hypersensitivity treatment: A systematic review.

The use of bioactive materials is a recent proposal in the treatment of dentin hypersensitivity (DH) due to the ability to stimulate the neoformation of a barrier on dentin surface. Questions have arisen about the effectiveness of the materials to reduce DH when compared to the control groups (placebo or non-bioactive substance). Thus, the aim of this systematic review was to evaluate the randomized controlled trials in adult patients for DH treatment with a dentifrice containing bioactive glass, applied either at-home or in-office. Methods: The study was registered in PROSPERO and followed PRISMA guidelines. Searches were carried out in four databases (Pubmed/Medline, CENTRAL, Wbb of Science, LILACS) spanning from February 2020 to March 2020, with no language or publication date restrictions. A supplementary hand-search was performed by checking the list of references. The so-called gray literature of the national and international databases for theses and dissertations, as well as unfinished, in progress and unpublished studies were also searched. Results: After reading the titles and abstracts, articles that were duplicated (74 records) or unrelated to the systematic review (76 records) were excluded. Fifteen studies were evaluated considering seven at low risk of bias, four at high risk and four at moderate risk. Conclusion: The bioactive compounds at low concentrations (2.5-7.5%) can be used as treatment of DH both at-home and in-office.

Shear Strength of Brackets Bonded with Universal Adhesive Containing 10-MDP after 20,000 Thermal Cycles.

OBJECTIVES: The aim of this study was to evaluate the shear bond strength of metal brackets bonded with different universal adhesive systems containing 10-MDP and Transbond Plus Self Etching Primer after 20,000 thermal cycles. Materials and Methods. A total of 130 sound bovine teeth were used, which are divided into 5 groups (n = 26) according to the adhesive system used: All-Bond Universal (Bisco), Ambar Universal (FGM), Clearfil Universal Bond (Kuraray), Single Bond Universal (3M/ESPE), and Transbond Plus SEP (3M/ESPE) as control. The adhesives were applied for 20 seconds and bonded with a resin Transbond XT (3M/ESPE). After this, the teeth were submitted to 20,000 cycles at 5°C and 55°C. Afterwards, the shear bond strength test was performed in a universal test machine (Instron 3342). The adhesive remnant index (ARI) was evaluated under a stereomicroscope at 10x magnification and scanning electronic microscopy (SEM, Hitachi 3030). The shear bond strength data were submitted to One-Way ANOVA (α = 0.05) and the ARI to the Kruskal-Wallis test (α = 0.05) and the ARI to the Kruskal-Wallis test (. RESULTS: Statistical analysis showed that the universal adhesive systems presented mean shear bond strength values similar to Transbond Plus SEP (p < 0.05). The universal adhesive presented similar ARI values among them but differed from those of Transbond Plus SEP (p < 0.05). The universal adhesive presented similar ARI values among them but differed from those of Transbond Plus SEP (. CONCLUSIONS: The results show that universal adhesive systems may be used for bonding metal brackets if the orthodontist wants to maintain dental enamel health.

Effect of bioactive glasses and neodymium:yttrium-aluminum-garnet laser on dentin permeability.

CONTEXT: Dental hypersensitivity and loss of dental tissues are commonly observed in patients, and most of the problems are caused due to total or partial exposure of dentinal tubules. AIMS: The purpose of this study is to evaluate the performance of 45S5 bioactive glass and niobophosphate (NbG) associated with neodymium: yttrium-aluminum-garnet (Nd:YAG) laser for the reduction of dentin permeability. MATERIALS AND METHODS: Fifty bovine dentin discs were made and distributed randomly into five groups (n = 10). The Nd:YAG laser was applied with the bioactive glasses using the energy parameters (60 and 80 mJ), forming the groups; NbG_60: NbG + Nd:YAG (60 mJ); NbG_80: NbG + Nd:YAG (80 mJ), 45S5_60: 45S5 + Nd:YAG (60 mJ); 45S5_80: 45S5 + Nd:YAG (80 mJ) and C: control (untreated dentin). The permeability was measured with a split chamber device. The samples were subjected to the erosive challenge and a new permeability measurement was done. Furthermore, the dentin was analyzed by scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS). STATISTICAL ANALYSIS USED: The data were analyzed using Kruskal-Wallis and Dunn's tests (α = 0.05). RESULTS: Greater reduction in dentinal permeability was observed for 45S5 bioactive glasses (45S5_60 and 45S5_80) followed by NbG_80 and NbG_60 (P < 0.05). The SEM/EDS analysis showed the formation of a barrier after the dentin treatment. CONCLUSIONS: Bioactive glasses with Nd:YAG laser on the dentin surface may be a promising alternative for the reduction of dentin permeability.