Effect of occlusal adjustment and subsequent repolishing on the surface roughness and volumetric wear of different types of glazed monolithic zirconia after chewing simulation.

The objective was to evaluate the effect of material (four monolithic zirconia) and surface condition [glazed (G) versus polished after simulation of occlusal adjustment (GAP)] on roughness and volumetric wear (VW) of dental zirconia after chewing simulation (CS). Zirconia specimens (ZS) were fabricated with an approximate diameter of 12.0 mm and a thickness of 1.0 mm. The four types of monolithic zirconia utilized were Prettau 4 Anterior (PA), Lava Plus (LP), Cercon hT (hT), and Cercon xT (xT). All specimens were coated with a thin and uniform layer of Prettau Plus glaze. Additionally, half of the ZS underwent a simulation of occlusal adjustment followed by clinical polishing. The sliding wear test was performed using a chewing simulator set at 30 N, 2 Hz, and 500,000 cycles, employing steatite specimens (SS) to simulate opposing dentition. ZS and SS underwent topographic analysis through optical profilometry to assess volumetric wear (VW) and surface roughness. The average roughness values (µm) of the zirconia ranged from 0.38h (PA-G before CS) to 2.55a (PA-GAP after CS), while for the antagonist the values ranged from 1.3b (LP-G before CS) to 2.6a (PA-GAP after CS). The VW values (mm3) of the ZS ranged from 0.7b (LP-G) to 2.5a (LP-GAP), while for the antagonist the values ranged from 0.17a (xT-GAP) to 0.33a (LP-G). The CS increased the roughness of all materials tested, regardless of the surface condition. The glazed condition showed lower roughness than the glazed/occlusal adjustment/polishing condition before the CS for three zirconia (PA, LP and xT) and after the CS for all materials. The surface condition did not significantly influence volumetric wear (VW) for three materials (PA, hT, and xT); however, for the Lava Plus (LP) group, the glazed condition resulted in reduced VW. The VW of the SS was unaffected by the material type or surface condition. In summary, zirconia specimens that underwent occlusal adjustment followed by repolishing demonstrated increased surface roughness compared to the glazed ones, while their wear behavior varied depending on the type of zirconia used.

Biomimetic bilayer scaffold from Bombyx mori silk materials for small diameter vascular applications in tissue engineering.

Enhancing the biocompatibility and mechanical stability of small diameter vascular scaffolds remain significant challenges. To address this challenge, small-diameter tubular structures were electrospun from silk fibroin (SF) from silk textile industry discarded materials to generate bilayer scaffolds that mimic native blood vessels, but derived from a sustainable natural material resource. The inner layer was obtained by directly dissolving SF in formic acid, while the middle layer (SF-M) was achieved through aqueous concentration of the protein. Structural and biological properties of each layer as well as the bilayer were evaluated. The inner layer exhibited nano-scale fiber diameters and 57.9% crystallinity, and degradation rates comparable with the SF-M layer. The middle layer displayed micrometer-scale fibers diameters with an ultimate extension of about 274%. Both layers presented contact angles suitable for cell growth and cytocompatibility, while the bilayer material displayed an intermediate mechanical response and a reduced enzymatic degradation rate when compared to each individual layer. The bilayer material emulates many of the characteristics of native small-diameter vessels, thereby suggesting further studies towards in vivo opportunities.

Nanomechanical and bending properties of nickel-titanium orthodontics archwires by depth-sensing indentation.

INTRODUCTION: This study aimed to identify the link between alloy microstructures and the nanomechanical properties of different orthodontic archwires containing nickel-titanium (NiTi) by sensing sliced areas. Previous studies have focused on analyzing and contrasting physical properties such as microhardness, elasticity modulus, and resistance; therefore, the trend is to consider microstructural characteristics in detail. METHODS: Thirty archwire samples from 3 different commercial brands, American Orthodontics (AO), 3M Unitek (3M), and Borgatta, were analyzed through scanning electron microscopy and energy-dispersive x-ray spectroscopy, transmission electron microscopy, atomic force microscopy, Berkovich nanoindentation, and microtensile microscopy to determine their chemical-crystallographic characteristics and nanomechanical and bending characteristics. RESULTS: The identified formulations of AO and 3M had averages of 20 wt%, for Ni and 15.4 wt% for Ti, with lower concentrations for Borgatta. Alloys of Ni and Ti were distributed in different concentrates in the matrix of the archwires. The nanomechanical properties showed high values of the elastic modulus (82.8 ± 3.6 GPa) and hardness (6.4 ± 1.2 GPa) and a minor deformation degree of 0.38% for the AO wires, although the bending strength exhibited the highest values for 3M. No corrosion was observed with a prolonged hydrolytic attack on the surface of any of the wires (0.0-0.5 National Bureau of Standards units). CONCLUSIONS: The highest nanomechanical properties and bending characteristics were observed for wires with higher NiTi precipitate contents, which were distributed differently in the alloy overall in the matrix. The nanoindentations sensed in different areas evidenced different mechanical properties for NiTi depending on its concentrations of Ti and enucleations.

Ability of a novel primer to enhance the polymerization of a self-cured resin composite.

OBJECTIVE: This study evaluated the degree of conversion (DC), polymerization kinetics, and temperature of a new self-cure bulk-fill resin-based composite (Stela Automix, SDI). METHODS: The study was divided into seven groups: (1) Stela Primer, (2) Stela Automix, (3) Stela Automix exposed to light for 20 s after 100 s, (4) Stela Primer with Stela Automix, (5) Stela Primer with Stela Automix and exposed to light for 20 s after 100 s, (6) Scotchbond Universal with Stela Automix, and (7) Scotchbond Universal with Stela Automix and exposed to light for 20 s after 100 s. The real-time reaction rates and DC at the bottom of 2 mm thick specimens at ∼32 °C were measured at 720 s after insertion using a spectrometer with an Attenuated Total Reflectance detector. The temperature of Stela, Stela exposed to light, Stela Primer with Stela, and Stela Primer with Stela exposed to light were measured by an infrared thermal camera in human molar teeth with Class I cavities. The temperature was recorded in real-time every 0.03 s for 720 s. The results were compared with ANOVA and Tukey's multiple comparison test (α = 0.05). RESULTS: The highest degree of conversion (DC) at the 2 mm depth was achieved when Stela Primer was combined with Stela (72.4 ± 3.5 % at 720 s). Stela could self-cure independently, but not as rapidly or effectively as when used with its Primer. The greatest temperature increase was for the light-cured Stela, followed by Stela Primer with Stela RBC exposed to light for 20 s. The Scotchbond Universal bonding system did not significantly increase the DC compared to Stela alone, except when exposed to light for 20 s, which slightly increased the final DC. Exposing Stela to light for 20 s did not improve the final DC of Stela as much as using the Stela Primer, but it did increase the temperature and prolonged the time taken to return to 37 °C. SIGNIFICANCE: The Stela primer accelerates the degree of conversion of Stela. The reaction occurred rapidly and achieved a higher DC at the bottom of the specimens where the Stela was in contact with the Stela primer. Exposing Stela to light for 20 s is not recommended. Instead, Stela should be used with Stela Primer.

Effect of radiotherapy, immediate dentin sealing and irrigation simulating single- or two-visits endodontic treatment on the bond strength to pulp chamber dentin: an in vitro study.

This study aimed to evaluate the influence of radiotherapy and different endodontic treatment protocols on the bond strength to pulp chamber dentin. Eighty mandibular molars were randomly divided into two groups (n = 40): non-irradiated and irradiated (60 Gy). The pulp chambers were sectioned, and each group was subdivided (n = 8), according to the endodontic treatment protocol: no treatment (Control); Single-visit; Two-visits; Immediate dentin sealing (IDS) + single-visit; and IDS + two-visits. Each endodontic treatment visit was simulated through irrigation with 2.5% NaOCl, 17% EDTA and distilled water. IDS was performed by actively applying two coats of a universal adhesive to the lateral walls of the pulp chamber. After, the pulp chambers were restored with resin composite and four sticks were obtained for microtensile test. In addition, the dentin of the pulp chamber roof was assessed for surface roughness, chemical composition, and topography after each treatment protocol. Two-way ANOVA, Tukey's post hoc, Mann-Whitney, Kruskal-Wallis and Dunn's post hoc were performed (α = 5%). The treatment protocol affected bond strength (p < 0.05), while the irradiation did not (p > 0.05). The control group presented the highest values (p < 0.05). The single-visit group demonstrated better performance compared to the other groups (p < 0.05), which did not differ from each other (p > 0.05) The use of IDS changed the surface roughness (p < 0.05), chemical composition (p < 0.05) and topography of the dentin. In conclusion, the treatment protocol influenced dentin adhesion, while irradiation did not.

Effect of multi-layer applications of self-etch universal bonding agents on the adhesion of resin composite to enamel.

To evaluate the effect of adhesive coats application on the enamel microtensile bond strength (µTBS) of universal adhesives, morphological etching pattern and their chemical interaction with hydroxyapatite (HA). Two universal adhesives were investigated: Scotchbond Universal (SBU, 3 M) and Prime&Bond Universal (PBU, Dentsply). The adhesives were applied in self-etching mode on bovine enamel (n = 8) in one (1L), two (2L) or three coats (3L) and light-cured as per manufacturers' instructions. As controls adhesives were applied to etched enamel (H3PO4-37% phosphoric acid). Bonded specimens were cut into sticks that were stored in deionized water for 24 h or 6 months prior to µTBS testing. Two-way ANOVA and Tukey's test were used for statistical analysis of bond strength with α = 5%. For morphological SEM analysis, enamel surfaces were treated as aforementioned and immediately rinsed with acetone. The intensity of monomer-calcium salt formation from each treatment was measured via infrared spectroscopy (ATR-FTIR). All treatments presented no significant reduction on µTBS after aging (p > 0.05). However, SBU attained highest µTBS when applied in 3L. PBU showed higher µTBS when applied to H3PO4 etched enamel than 1L or 2L. Etching pattern was enhanced by 3L application, particularly with PBU. Chemical interaction was notably higher for SBU than PBU, with no relevant differences with more layers or prior H3PO4-etching. The application of three adhesive coats of universal adhesives in self-etch mode using may enhance the bonding performance and etching pattern to enamel, surpassing the H3PO4-etched enamel bond for SBU. The chemical interaction with calcium from enamel is not affected by number of coats or prior phosphoric acid etching.

Microstructural characterization, mechanical and microbiological properties of acrylic resins added with reduced graphene oxide.

To evaluate the microstructural characterization, mechanical properties and antimicrobial activity of acrylic resins incorporated with different concentrations of reduced graphene oxide (rGO). Specimens were made of self-cured and heat-cured acrylic resins for the control group and concentrations of 0.5%, 1%, and 3%. The microstructural characterization was evaluated by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDS). For mechanical testing, flexural strength, and Knoop hardness tests were performed. Microbiological evaluations were performed by colony forming units (CFU) analysis, tetrazolium salt reduction (XTT), and SEM images. The modified acrylic resins showed increased mechanical properties at low concentrations (p < 0.05) and with reduced S. mutans (p < 0.05). Reduced graphene oxide interfered with the mechanical performance and microbiological properties of acrylic resins depending on the concentration of rGO, and type of polymerization and microorganism evaluated. The incorporation of graphene compounds into acrylic resins is an alternative to improve the antimicrobial efficacy and performance of the material.

Exploring the effectiveness of doxycycline in restorative dentistry: a systematic review of in vitro studies.

This systematic review evaluated the efficacy of doxycycline in MMP inhibition, its antibacterial action, and other properties relevant to dental materials testing. The study protocol was registered at the Open Science Framework ( https://doi.org/10.17605/OSF.IO/ZVK2T ). Reporting was based on PRISMA statement. The search was carried out in the databases: PubMed, Scopus, Web of Science, Embase, Lilacs, and Google Scholar. Articles were restricted to Portuguese, English, and Spanish, with no date limit. In vitro studies were selected based on the following outcomes: DOX antibacterial and anti-metalloproteinase activity and its influence in physico-chemical properties. Two researchers independently selected the articles and collected the data. Of 1507 documents, 82 were fully evaluated and 21 were included. Different forms of doxycycline incorporation were found, both as free form and incorporated into carrier agents. The drug was tested as primers, incorporated in adhesive or glass ionomer cement. No studies were found that evaluated its incorporation in resin composite or resin cement. The results confirmed the therapeutic properties of the medication, with more significant results when incorporated in an adhesive. However, although promising, the use of this substance requires standardization in application methods and adopted concentrations, allowing for more direct comparisons between studies. Furthermore, long-term studies are interesting to conduct, ensuring biocompatibility and complete understanding of long-term effects on dental materials.

Efficiency of cavitary varnishes containing experimental bioglass particles in the occlusion of dentinal tubules.

This research aims to evaluate the efficiency of cavitary varnishes containing experimental bioglasses in the occlusion of dentinal tubules. One hundred and sixty-eight cervical buccal dentin samples were obtained from bovine teeth. Samples were randomized into the following groups: I. Distilled Water (DW); II. Cavity Varnish (CV); III. Colgate® Sensitive Pro-Relief™ (CS); IV. 45S5 Bioglass (45S5); V. KSr Bioglass strontium potassium (KSr); VI. P Bioglass phosphorus (P); and VII. PSi Bioglass phosphorus silica (PSi). The treatments were applied to the surfaces of the samples, which were then subjected to simulated brushing. The samples were analyzed for a) characterization of bioactive glasses; b) surface roughness; c) descriptive analysis of the dentin surface; d) total versus occluded number of dentinal tubules; e) diameter of the dentinal tubules; f) chemical composition of the dentin surfaces, and g) dentin permeability. All groups treated with biomaterials without the brushing challenge showed an increase in roughness and (total or partial) occlusion of the dentinal tubules. The PSi group had the best values for occlusion, while the KSr group had the highest calcium and phosphorus concentrations. After the brushing challenge the roughness was controlled by the presence of biomaterials; 45S5, KSr, and PSi showed occlusion of the dentin tubules. All bioactive glasses showed reduced tooth permeability compared to distilled water. The PSi group had the smallest tubule diameter and highest phosphorus concentration. KSr and PSi bioglasses are promising materials for dentin occlusion and remineralization and are promising new biomaterials for the treatment of dentin hypersensitivity.

Adaptation and Biomechanical Performance of Custom-Fit Mouthguards Produced Using Conventional and Digital Workflows: A Comparative In Vitro Strain Analysis.

BACKGROUND/OBJECTIVES: The use of different models for the fabrication of custom-fit mouthguards (MTGs) can affect their final thickness, adaptation, and shock-absorption properties. This study aimed to evaluate the adaptation, thickness, and shock absorption of ethylene-vinyl acetate (EVA) thermoplastic MTGs produced using conventional plaster or three-dimensional (3D) printed models. MATERIALS AND METHODS: A typical model with simulated soft gum tissue was used as the reference model to produce MTGs with the following two different protocols: plast-MTG using a conventional impression and plaster model (n = 10) and 3DPr-MTG using a digital scanning and 3D printed model (n = 10). A custom-fit MTG was fabricated using EVA sheets (Bioart) plasticized over different models. The MTG thickness (mm), internal adaptation (mm) to the typodontic model, and voids in the area (mm2) between the two EVA layers were measured using cone-beam computed tomography images and Mimics software (Materialize). The shock absorption of the MTG was measured using a strain-gauge test with a pendulum impact at 30° with a steel ball over the typodont model with and without MTGs. Data were analyzed using one-way analysis of variance with repeated measurements, followed by Tukey's post hoc tests. RESULTS: The 3DPr-MTG showed better adaptation than that of the Plast-MTG at the incisal/occlusal and lingual tooth surfaces (p < 0.001). The 3DPr-MTG showed a thickness similar to that of the Plast-MTG, irrespective of the measured location. MTGs produced using both model types significantly reduced the strain values during horizontal impact (3DPr-MTG 86.2% and Plast-MTG 87.0%) compared with the control group without MTG (p < 0.001). CONCLUSION: The MTGs showed the required standards regarding thickness, adaptation, and biomechanical performance, suggesting that the number and volume of voids had no significant impact on their functionality. Three-dimensional printed models are a viable alternative for MTG production, providing better adaptation than the Plast-MTG at the incisal/occlusal and lingual tooth surfaces and similar performance as the MTG produced with the conventional protocol.

Casting Skin Dressing Containing Extractions of the Organic Part of Marine Sponges for Wound Healing.

Skin wounds are extremely frequent injuries related to many etiologies. They are a burden on healthcare systems worldwide. Skin dressings are the most popular therapy, and collagen is the most commonly used biomaterial, although new sources of collagen have been studied, especially spongin-like from marine sponges (SPG), as a promising source due to a similar composition to vertebrates and the ability to function as a cell-matrix adhesion framework. Despite evidence showing the positive effects of SPG for tissue healing, the effects of skin dressings manufactured are still limited. In this context, this study aimed at investigating the effects of collagen skin dressings in an experimental model of skin wounds in rats. For this purpose, SEM, FTIR, cell viability, morphological and morphometric aspects, collagen deposition, and immunostaining of TGF-ß and FGF were evaluated. The results demonstrated micro- and macropores on the rough surface, peak characteristics of collagen, and no cytotoxicity for the skin dressing. Also, the control group (CG) after 5 and 10 days exhibited an intense inflammatory process and the presence of granulation tissue, while the treated group (TG) exhibited re-epithelialization after 10 days. The evaluation of granulation tissue and neoepithelial length had an intragroup statistical difference (p = 0.0216) and no intergroup difference. Birefringence demonstrated an organized mesh arranged in a network pattern, presenting type I and type III collagen fibers in all groups. Moreover, in the morphometric evaluation, there were no statistical differences in intergroups or time points for the different types of collagen evaluated. In conclusion, these findings may indicate that the dressing has not exacerbated the inflammatory process and may allow faster healing. However, further studies using a critical wound healing injury model should be used, associated with longer experimental periods of evaluation, to further investigate the effects of these promising therapeutic approaches throughout the skin repair process.

Cotton cellulose nanofiber/chitosan scaffolds for skin tissue engineering and wound healing applications.

Chitosan (CS) is a promising polymeric biomaterial for use in scaffolds forin vitroskin models and wound dressings, owing to its non-antigenic and antimicrobial properties. However, CS often exhibits insufficient physicochemical properties, mechanical strength, and bioactivity, limiting its efficacy in demanding applications. To address these challenges, cotton cellulose nanofibers (CNFs) represent a promising nanomaterial for enhancing CS-based scaffolds in tissue engineering. CNF offers superior stiffness, and mechanical properties that enhance cellular adhesion and proliferation, both crucial for effective tissue regeneration and healing. This study aimed to develop and characterize a scaffold combining cotton CNF and CS, focusing on its cytocompatibility with human fibroblasts and keratinocytes. The cotton CNF/CS scaffold was fabricated using the casting technique, and its physicochemical properties and cellular compatibility were assessedin vitro. The results demonstrated that incorporating cotton CNF significantly enhanced the stability of the CS matrix. The CS scaffold with 1000 µg ml-1of cotton CNF exhibited increased roughness and reduced rupture strain compared to the pure CS scaffold. The cotton CNF/CS scaffold effectively promoted the adhesion, viability, proliferation, migration, and collagen synthesis of skin cells. Notably, increased cell viability was observed in human fibroblasts cultured on scaffolds with higher concentrations of cotton CNF (100 and 1000 µg ml-1). Based on the findings, the cotton CNF/CS scaffold demonstrates enhanced physicochemical properties and bioactivity, making it a promising candidate for the development ofin vitrohuman skin models and wound healing dressings.

Valorization of piassava fiber by its incorporation in adobe bricks.

This study investigates valorization of piassava fiber through its incorporation in adobe bricks. The objective was to analyze the properties of adobe bricks reinforced with varying weight fractions of piassava fiber. The fibers were characterized for their chemical and physical characteristics, while the sand and clay were characterized for granulometry, XRD patterns, and EDX. Initial bricks were prepared with a constant piassava fiber weight fraction of 3% and varying sand:clay weight ratios. The mechanical properties of the adobe bricks were evaluated, and subsequent investigations involved variable fiber weight fractions of 0.5%, 1%, and 3%. Characterization included compressive characterization, apparent density, three-point bending, resistance to water erosion, and cracking behavior. The results showed that the physical and chemical characteristics of the fibers were consistent with the existing literature. The adobe bricks exhibited a range of apparent density values and compressive strength, with the S40C60P3 brick demonstrating higher strength and reduced crack visibility. The bricks with 3% fiber content outperformed others in terms of bending strength and displacement before fracture. Erosion tests revealed that higher fiber contents resulted in lower levels of mass loss and erosion depth. These findings highlight the potential of piassava fiber incorporation in adobe bricks for enhancing their properties.

Resin infiltrant with antibacterial activity: effects of incorporation of DMAHDM monomer and NACP on physical and antimicrobial properties.

OBJECTIVES: Considering the fact that resin infiltrants lack antibacterial activity, this study assessed the influence of the quaternary ammonium monomer dimethylaminohexadecyl methacrylate (DMAHDM) and amorphous calcium phosphate nanoparticles (NACP) on the physical and antibacterial properties of an experimental resin infiltrant (ERI). METHODOLOGY: The following groups were established: ERI (75/25 wt.% TEGDMA/BISEMA), ERI + 2.5% DMAHDM (2.5DM), ERI + 5% DMAHDM (5DM), ERI + 2% NACP (NACP), ERI + 2.5% DMAHDM + 2% NACP (2.5DM_NACP), ERI + 5% DMAHDM + 2% NACP (5DM_NACP), and Icon® (IC), a commercial resin infiltrant. Degree of conversion (DC; n=4), sorption and solubility (SO/SOL; n=8), and contact angle (CA; n=10) tests were conducted. Biofilm biomass (BB; n=6) and bacterial metabolism (BM; n=8) were evaluated after Streptococcus mutans (UA159) cultivation for 48 h on material samples. Data were evaluated by one-way ANOVA and Tukey or Games-Howell post hoc tests (α=0.05). RESULTS: IC exhibited the highest DC, with no difference from 2.5DM and 5DM. IC showed the lowest CA. IC had the lowest SO, followed by ERI, which had the lowest SOL, with no difference from IC. 5DM_NACP showed the lowest biofilm biomass, similar to 2.5DM and 5DM. Resin infiltrants containing DMAHDM showed reduced bacterial metabolism. CONCLUSIONS: DMAHDM, with or without NACP, demonstrated significant antibacterial activity, while NACP impaired DC. Both DMAHDM and NACP increased the contact angle, sorption, and solubility of the resin infiltrant, which may affect the material's clinical performance.

Effect of argon plasma and dentin rehydration on bond strength of dental adhesives to etched dentin.

This study investigated the effects of nonthermal atmospheric pressure plasma (NAPP) application and dentin rehydration with water (REHY) on bond strength (BS) of adhesives. Three etch-and-rinse adhesives were tested: Scotchbond Multi-Purpose (SBM / water-based primer + adhesive resin), Gluma Bond Universal (GBU / single-bottle containing acetone as organic solvent) and Prime&Bond Universal (PBU / single-bottle containing propanol as organic solvent). Adhesives were applied: 1- to phosphoric acid-etched dentin (Control), 2- after NAPP application for 45 seconds to etched dentin or 3- after REHY with water (10 seconds) of plasma-treated etched dentin. BS was performed using human molars and microtensile test, in which specimens were tested after 24 hours or one year (n=6). BS data were analyzed by three-way mixed ANOVA and Bonferroni's test (α=0.05). The morphology of etched dentin (n=3) and the dentin-adhesive interfaces (n=3) were evaluated using SEM. NAPP and REHY did not increase the BS of GBU and PBU. The BS of SBM to etched dentin not treated with NAPP (Control) reduced significantly after one year. The PBU adhesive showed the highest bond strength to dentin when the adhesives tested were applied after REHY. Phosphoric acid demineralized dentin to a depth of 5 mm that allowed the adhesive penetration into the dentinal tubules, forming the resin tags. Interfacial structures were maintained after one year. Argon plasma treatment was not beneficial in increasing the dentin bond strength of adhesives to etched-dentin at 24 hours. However, rehydration after plasma application prevented the bond strength reduction for three-step adhesive after one year.

Biological Properties of Bioceramic Sealers on Osteoblastic Cells: A Comparative Study.

This study aimed to assess the biological properties of two ready-to-use bioceramic sealers (EndoSequence BC Sealer - EBCS; Bio-C Sealer - BCS) on osteoblastic lineage cells. MC3T3 osteoblast-like cells were exposed to extracts of bioceramic materials. Cytotoxicity was evaluated using the MTT method, genotoxicity was assessed by the micronucleus test and the expression of BMP1, BMP2 and ALP was measured by RT-qPCR, after 1, 3 and 7 days. Wound healing was monitored at 1, 2 and 3-day intervals using the scratch test. Statistical analysis involved a two-factor ANOVA, followed by the Tukey Test for multiple comparisons (α=0.05). Cytotoxicity assessment revealed no significant differences between the materials and the control group at any of the time points, indicating that neither material exhibited cytotoxic effects. However, both cements induced greater micronuclei formation compared to the control on days 1 and 7 (p<0.05) when evaluating genotoxicity. No significant differences between the groups were observed in wound healing at any of the time intervals. Both biomaterials upregulated the expression of BMP1, BMP2 and ALP. The two bioceramic sealers exhibited comparable biological properties, including cytocompatibility, promotion of wound healing, and upregulation of bone formation-related genes in osteoblast-like cells. While these results suggest the potential for safe clinical application, the observed genotoxicity warrants caution. Therefore, while the null hypothesis-that the two bioceramic sealers exhibit analogous properties-was accepted in terms of cytocompatibility and gene expression, further investigation is essential to fully ensure their safety and efficacy in bone-related procedures.

Evaluation of the bonding strength of conventional, anatomized, adjustable, and CAD/CAM milled fiberglass posts in weakened endodontically treated roots.

This study evaluated the bond strength (BS) of conventional, anatomized, adjustable, and CAD/CAM fiberglass post systems. Forty maxillary canine roots were weakened, endodontically treated, and divided into four groups (n=10). A slice from each of the three sections (cervical, middle, apical) of the root canal was subjected to the push-out test and the failure pattern was subsequently analyzed. The most apical slice was subjected to analysis of the cementation line thickness by scanning electron microscopy (SEM). Data regarding the BS and cementation line thickness were subjected to the Shapiro-Wilk normality test followed by the variance and Tukey tests. Data failure patterns were expressed as a percentage and submitted to the chi-square test. Conventional fiberglass posts had the lowest BD compared to the other fiberglass posts (p<0.05). All fiberglass posts exhibited a higher percentage of adhesive failures to dentin. The SEM demonstrated a thicker cementation line for the conventional post compared to the other groups (p<0.05), as well as gaps and voids in the cementing material. The anatomized, adjustable, and CAD/CAM milled fiberglass post systems demonstrated a superior BS and adaptation to the root dentin compared to the conventional fiberglass post.

A comprehensive study on MDP effects: Microshear bond strength and fatigue resistance in 4YSZ ceramics.

The aim of this study is to assess the presence of MDP at various stages of the bonding procedure, enhance the adhesive and mechanical behavior of cemented zirconia ceramics. Fifty ceramic slices (15 × 15 × 2 mm) and 48 discs (Ø= 10 mm, 1 mm thickness) were prepared, sintered, air-abraded with aluminum oxide, and allocated considering: 1) microshear bond strength (µSBS) between ceramic slices and luting agent cylinders (height= 1 mm, Ø= 1.2 mm); 2) fatigue behavior, ceramic discs paired and bonded onto fiber-epoxy resin discs (Ø= 10 mm, 2.5 mm thickness), and then mechanically tested (cyclic loading, starting at 400N, with increments of 100N, until failure). Four experimental groups were defined: Universal Primer (MDP primer+non-MDP resin cement - RC), Universal Adhesive (MDP adhesive+non-MDP RC), Cement (no primer+MDP RC), and Primer+Cement (MDP primer + MDP RC). For both outcomes, half of the specimens were tested after 24 hours, and half after aging. Bond strength data was analyzed via two-way ANOVA and Tukey post-hoc tests, while fatigue data went through Kaplan-Meier and Mantel-Cox post hoc tests. Regarding µSBS, aging impaired adhesion only for the Primer+Cement group (p<0.001). Universal Primer and Universal Adhesive showed the highest bond strength (p<0.05). Despite that, fatigue data indicates no significant differences (p>0.05). In conclusion, systems with MDP-containing components associated with non-MDP resin cement demonstrated enhanced adhesive capability for zirconia restorations. Nevertheless, no differences in terms of mechanical reinforcement were observed.

Optical properties and color stability of a translucent zirconia: effects of finishing after grinding.

This study evaluated the effect of grinding and finishing treatments (polishing or glaze) on the color stability, translucency and opalescence of a translucent zirconia (3Y-TZP) after immersion in red wine. Discs (Ø= 12 mm; thickness 0.8 mm) of 3Y-TZP (Zenostar T, Ivoclar AG) were randomly allocated (n= 8) according to the surface treatment factor: Ctrl - as-sintered; Gr - grinding with diamond bur #4219; Gr + Pol - grinding followed by polishing; Gr + Gl - grinding followed by glaze. Surface roughness and scanning electron microscopy were carried out. All specimens were subjected to daily immersions in red wine for 30 minutes during 18 days. The color differences (ΔE00) were measured prior, after 9 and 18 days of immersion through the CIEDE2000 formula, as same as translucency (TP00) and opalescence (OP) parameters. Kruskal Wallis, repeated measures ANOVA/Tukey, and Spearman's correlation tests were performed to evaluate the roughness, optical and correlation data, respectively. The Gr + Gl depicted the lowest ΔE00 value after 9 days. The Gr group showed the greatest ΔE00 values in all immersion times, whereas the other groups presented similar behavior after 18 days. The Gr and Gr + Pol groups had the highest Ra and Rz values. The correlation between roughness and color change was moderate and significant (p= 0.02, r= 0.42). No differences were observed for TP00 and OP. The surface treatments affected the roughness and color stability of zirconia, being glaze application more effective to reduce color alterations after the immersion protocol.

Fatigue behavior of sintered, glazed and glass-infiltrated surfaces of 5Y-PSZ bonded plates.

This study evaluated the effect of different occlusal surface finishes (glaze and silica glass infiltration) on surface characteristics and fatigue behavior of partially stabilized zirconia (PSZ) plates adhesively bonded onto epoxy resin discs. PSZ disc specimens (n = 15; Katana blocks STML, Kuraray Noritake Dental) were produced (Ø = 10 mm; thickness = 1.2 mm) and allocated into 3 groups: As sintered (S), silica glass infiltration (SGI), and glaze application (G). The PSZ intaglio surface was air-abraded with 50-µm alumina powder followed by bonding agent application. All produced PSZ were adhesively cemented onto dentin analogue discs made of epoxy resin material (Ø = 10 mm; thickness = 2 mm). Step stress fatigue test was performed (load ranging from 200 to 1800 N; step size 100 N and 10,000 cycles; 20 Hz). The topographic, microstructural, and fractographic analyses were performed by scanning electron microscopy. Results: No statistically significant difference in fatigue behavior was detected among the groups. All failures started at the bonding surface. Silica glass-infiltration and glaze layer application provided a smoothing effect, while the sintered group had a surface with grooves. The occlusal surface finishing method (silica glass infiltration or glazing) had no deleterious effect on fatigue behavior of adhesively bonded PSZ plates.