Mechanical and optical properties of a borosilicate glass used to improve the finishing of 3Y-TZP restorations.

Borosilicate glass was developed to enhance the mechanical behavior and smoothness of dental zirconia as an alternative to conventional glaze. This study assessed the mechanical and optical properties of 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) coated with borosilicate glass or a commercial glaze fired for an extended period of time. Disc-shaped 3Y-TZP zirconia specimens (Zpex, Tosoh) were sintered at 1550°C for 2 hours. The specimens were divided into three groups: as-sintered (control, C); commercial glaze (G); and borosilicate glass (SL). The glaze and borosilicate glass were applied over the zirconia and fired for 20 minutes at 950°C and 1200°C, respectively. Biaxial flexural strength, fractography, X-ray diffraction (XRD), roughness (Ra and Rz), fracture toughness (Vickers indentation method), color difference (∆E00), and translucency (TP00) analyses were conducted. The t-test or the one-way ANOVA and Tukey's tests were used to analyze the data (α = 0.05). Flexural strength data were subjected to the Weibull analysis. The SL group exhibited the highest flexural strength (1025.8 MPa), whereas the C (859.41 MPa) and G (816.0 MPa) groups exhibited similar values. The SL group also had the highest characteristic strength. The fracture origin in all groups was on the zirconia surface. XRD analysis revealed that the specimens from the SL group contained tetragonal, cubic, and monoclinic phases. The SL group presented the lowest surface roughness. Fracture toughness in the SL group was lower than in the C group, but similar to that observed in the G group. The translucency and color differences observed in the G and SL groups were similar. Borosilicate glass enhanced the flexural strength of 3Y-TZP, promoted the smoothest surface, and exhibited optical properties similar to those of the glaze.

An investigation on the physical properties of cementitious pastes modified with low dosage of waste glass powder and silica fume.

Portland cement (PC) production is among the industrial activities that most emit harmful gases. Its replacement to green binders turns into a timely issue to face the global restrictions due to climate changes. In this study, some properties of cementitious pastes prepared with waste packing glass powder (GP) and silica fume (SF) were characterized in line with a prefixed alkaline equivalent limit. These materials were obtained in Northeastern Brazil. Grinding operations used to produce GP into four size ranges ([45-75] µm, < 45 µm; [25-45] µm, < 25 µm) were disclosed. X ray diffraction showed that GP and SF substitutions did not change the hydration products commonly observed in PC pastes. The portlandite content measured with thermogravimetry was affected by GP size in both unitary and binary substitutions. The compressive strength measured after 56 days of curing was dependent on portlandite and void index contents measured in hardened pastes. Scanning electron microscopy coupled to energy dispersive spectroscopy were useful to show the effect of the particle size on the pozzolanic activity. It was found that 5% of PC replacement for GP < 25 µm was enough to raise the compressive strength by ~5%. For binary substitution, the strength increasing was ~ 20 %. The collectors of solid residues are the main players of waste glass recycling in Brazil. It is expected that the results of this study contribute to take out these workers from the fringes of the citizenship.

Physicochemical characterization of experimental resin-based materials containing calcium orthophosphates or calcium silicate.

OBJECTIVE: To evaluate experimental dimethacrylate-based materials containing calcium orthophosphates or calcium silicate particles in terms of their optical, mechanical and Ca2+ release behaviour. METHODS: Dicalcium phosphate dihydrate (DCPD), hydroxyapatite (HAp), beta-tricalcium phosphate (ß-TCP) or calcium silicate (CaSi) particles were added to a photocurable BisGMA/TEGDMA resin (1:1 in mols) at a 30 vol% fraction. Materials containing silanized or non-silanized barium glass particles were used as controls. Degree of conversion (DC) at the top and base of 2-mm thick specimens was determined by ATR-FTIR spectroscopy (n = 5). Translucency parameter (TP) and transmittance (%T) were determined using a spectrophotometer (n = 3). Biaxial flexural strength (BFS) and flexural modulus (FM) were determined by biaxial flexural testing after 24 h storage in water (n = 10). Ca2+ release in water was determined during 28 days by inductively coupled plasma optical emission spectrometry (n = 3). Statistical analysis was performed using ANOVA/Tukey test (DC: two-way; TP, %T; BFS and FM: one-way; Ca2+ release: repeated measures two-way, α = 5 %). RESULTS: CaSi and ß-TCP particles drastically reduced DC at 2 mm, TP and %T (p < 0.001). Compared to both controls, all Ca2+-releasing materials presented lower BFS (p < 0.001) and only the material with DCPD showed significantly lower FM (p < 0.05). The material containing CaSi presented the highest Ca2+ release, while among materials formulated with calcium orthophosphates the use of DCPD resulted in the highest release (p < 0.001). SIGNIFICANCE: CaSi particles allowed the highest Ca2+ release. Notwithstanding, the use of DCPD resulted in a material with the best compromise between optical behaviour, DC, strength and Ca2+ release.

Development of PHBV electrospun fibers containing a borate bioactive glass doped with Co, Cu, and Zn for wound dressings.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanofibers embedded with borate glasses of 45B5 composition doped with Co2+, Cu2+, and Zn2 +(46.1 B2O326.9-X CaO24.4 Na2O2.6 P2O5, X CoO/CuO/ZnO mol % (X = 0-5)) were produced by electrospinning for wound healing applications. Prior to their addition, the glasses exhibited two broad halos typical of a vitreous borate network, which were mainly composed of ring-type metaborate structural units. The particle distribution in the PHBV nanofibers embedded with 45B5 borate bioactive glasses is present in isolated and agglomerated states, being partially coated by a polymeric layer-except for the cobalt-doped glass, which resulted in a successful encapsulation with 100% embedding efficiency. The incorporation of the glasses reduced the PHBV crystallinity degree and its decomposition temperature, as well as its mechanical properties, including Young's modulus, tensile strength, and elongation at break. The neat PHBV fibers and those containing the cobalt-doped glasses demonstrated great cytocompatibility with human keratinocytes (HaCat), as suggested by the high cell viability after 7 days of exposure. Further studies are needed to fully understand the wound healing potential of these fibers, but our results significantly contribute to the area.

Optimized Electrophoretic Deposition of Chitosan/Mesoporous Glass Nanoparticles with Gentamicin on Titanium Implants: Enhancing Hemocompatibility and Antibacterial Activity.

Titanium-based implants have long been studied and used for applications in bone tissue engineering, thanks to their outstanding mechanical properties and appropriate biocompatibility. However, many implants struggle with osseointegration and attachment and can be vulnerable to the development of infections. In this work, we have developed a composite coating via electrophoretic deposition, which is both bioactive and antibacterial. Mesoporous bioactive glass particles with gentamicin were electrophoretically deposited onto a titanium substrate. In order to validate the hypothesis that the quantity of particles in the coatings is sufficiently high and uniform in each deposition process, an easy-to-use image processing algorithm was designed to minimize human dependence and ensure reproducible results. The addition of loaded mesoporous particles did not affect the good adhesion of the coating to the substrate although roughness was clearly enhanced. After 7 days of immersion, the composite coatings were almost dissolved and released, but phosphate-related compounds started to nucleate at the surface. With a simple and low-cost technique like electrophoretic deposition, and optimized stir and suspension times, we were able to synthesize a hemocompatible coating that significantly improves the antibacterial activity when compared to the bare substrate for both Gram-positive and Gram-negative bacteria.

Intra-radicular retention with custom designed CAD-CAM fibRe-reinforced composite post-core: a dental technique.

A technique is outlined for utilising a polymeric composite reinforced with glass fibres in a three-dimensional mesh as a post-core in aesthetic cases. The clinical procedure involves obtaining an impression of the root canal space, scanning the definitive cast, and milling a fibre-reinforced composite post-core. Subsequently, the intra-radicular post-core is cemented using an adhesive resin cement. The use of custom-made computer-aided design-computer-aided manufacturing (CAD-CAM) fibre-reinforced composite post-core facilitates repairability, provides better adaptation to the root canal space, avoids uneven cement thickness, ensures chemical adhesion to resin cement, and promotes favourable aesthetics when combined with all-ceramic crowns.

The MATH test. A three-phase assay?

This study aimed to investigating the possible interference caused by glass test tubes on the quantification of bacterial adhesion to hydrocarbons by the MATH test. The adhesion of four bacteria to hexadecane and to glass test tubes was evaluated employing different suspending polar phases. The role of the ionic strength of the polar phase regarding adhesion to glassware was investigated. Within the conditions studied, Gram-positive bacteria adhered to both the test tube and the hydrocarbon regardless of the polar phase employed; meanwhile, Escherichia coli ATCC 25922 did not attach to either one. The capacity of the studied microorganisms to adhere to glassware was associated with their electron-donor properties. The ionic strength of the suspending media altered the patterns of adhesion to glass in a strain-specific manner by defining the magnitude of electrostatic repulsion observed between bacteria and the glass surface. This research demonstrated that glass test tubes may interact with suspended bacterial cells during the MATH test under specific conditions, which may lead to overestimating the percentage of adhesion to hydrocarbons and, thus, to erroneous values of cell surface hydrophobicity.

Ultrasonic activation of adhesive systems increases bond strength and intratubular penetration of resin cement in root dentin subjected to radiation therapy.

OBJECTIVE: This study aimed to evaluate the effect of ultrasonic activation of etch-and-rinse and self-etch adhesive systems on the bond strength of resin cement to irradiated root dentin. MATERIALS AND METHODS: Eighty human maxillary anterior teeth were distributed into 8 groups (n = 10), according to the type of adhesive system used (etch-and-rinse and self-etch), the ultrasonic activation of the adhesive systems, and the dentin condition (irradiated or non-irradiated - 70 Gy). Endodontic treatment was performed followed by fiberglass post-space preparation. After fiberglass posts' luting, the roots were transversely sectioned on dentin discs and submitted to the push-out bond strength test (0.5 mm/min). The fractured specimens were analyzed under a stereomicroscope and Scanning Electron Microscope (SEM) for failure mode classification. One of the dentin discs was analyzed under SEM to evaluate the characteristics of the adhesive interface. RESULTS: Irradiated specimens had lower bond strength than non-irradiated specimens (P < 0.0001). Ultrasonic activation of both adhesive systems increased the bond strength of the resin cement to irradiated dentin (P < 0.0001). Radiotherapy significantly affected the failure mode in the middle (P = 0.024) and apical thirds (P = 0.032) (adhesive failure). CONCLUSION: Non-irradiated specimens had a more homogeneous adhesive interface. When ultrasonically activated, both adhesive systems showed a greater number of resinous tags, regardless of the dentin condition. CLINICAL RELEVANCE: Ultrasonic activation of adhesive systems is a feasible strategy to enhance fiberglass posts retention in oncological patients.

Aspects of glass and hybridization protocols for bonding of fiber posts to root dentine.

This study evaluated bond strength of glass fiber posts to root dentin using push-out (PO) and diametral compression (DC), testing glycolic acid as a conditioner and varying dentin moisture. An additional aim was to test whether DC can be an alternative test to PO for bond strength assessment. Eighty bovine teeth were divided into eight groups (n = 10) defined by the use of either 37% glycolic acid or 37% phosphoric acid (PA) on moist or wet dentin before bonding with either Adapter SingleBond/RelyX ARC or One Step Plus/Duo-Link Bisco. Each tooth provided discs with an internal diameter of 2 mm, external diameter of 5 mm, and height of 2 mm, which underwent PO and DC. Finite element analysis (FEA) was carried out on 3D models. When analyzing PO results through linear regression, the highest values of bond strength were observed using glycolic acid on wet dentin in the cervical and middle thirds of the teeth. Analyzing DC results, the only statistical influence on values was the dental thirds. The scatterplot of the DC results and the PO bond strength values indicated no relationship between the results of the two tests (r = 0.03; p = 0.64). PO test detected more sensitive changes in bond strength values than DC.

Fatigue and failure mode analyses of glass infiltrated 5Y-PSZ bonded onto dentin analogues.

The purpose of this study was to evaluate the fatigue survival of 5Y-PSZ zirconia infiltrated with an experimental glass and bonded onto dentin analogues. Disc-shaped specimens of a 5Y-PSZ (Katana UTML Kuraray Noritake) were cemented onto dentin analogs (NEMA G10) and divided into four groups (n = 15): Zctrl Group (control, without infiltration); Zglz Group (Glaze, compression surface); Zinf-comp Group (Experimental Glass, compression surface); Zinf-tens Group (Experimental Glass, tension surface). Surface treatments were varied. Cyclic fatigue loading, oblique transillumination, stereomicroscope examination, and scanning electron microscopy were performed. Fatigue data were analyzed (failure load and number of cycles) using survival analysis (Kaplan-Meier and Log-Rank Mantel-Cox). There was no statistically significant difference in fatigue survival between the Zglz, Zctrl, and Zinf-comp groups. The Zinf-tens group presented a significantly higher failure load when compared to the other groups and exhibited a different failure mode. The experimental glass effectively infiltrated the zirconia, enhancing structural reliability, altering the failure mode, and improving load-bearing capacity over more cycles, particularly in the group where the glass was infiltrated into the tensile surface of the zirconia. Glass infiltration into 5Y-PSZ zirconia significantly enhanced structural reliability and the ability to withstand loads over an increased number of cycles. This approach has the potential to increase the durability of zirconia restorations, reducing the need for replacements and save time and resources, promoting efficiency in clinical practice.

Dental implant and abutment in PEEK: stress assessment in single crown retainers on anterior region.

OBJECTIVE: Stress distribution assessment by finite elements analysis in poly(etheretherketone) (PEEK) implant and abutment as retainers of single crowns in the anterior region. MATERIALS AND METHODS: Five 3D models were created, varying implant/abutment manufacturing materials: titanium (Ti), zirconia (Zr), pure PEEK (PEEKp), carbon fiber-reinforced PEEK (PEEKc), glass fiber-reinforced PEEK (PEEKg). A 50 N load was applied 30o off-axis at the incisal edge of the upper central incisor. The Von Mises stress (σvM) was evaluated on abutment, implant/screw, and minimum principal stress (σmin) and maximum shear stress (τmax) for cortical and cancellous bone. RESULTS: The abutment σvM lowest stress was observed in PEEKp group, being 70% lower than Ti and 74% than Zr. On the implant, PEEKp reduced 68% compared to Ti and a 71% to Zr. In the abutment screws, an increase of at least 33% was found in PEEKc compared to Ti, and of at least 81% to Zr. For cortical bone, the highest τmax values were in the PEEKp group, and a slight increase in stress was observed compared to all PEEK groups with Ti and Zr. For σmin, the highest stress was found in the PEEKc. Stress increased at least 7% in cancellous bone for all PEEK groups. CONCLUSION: Abutments and implants made by PEEKc concentrate less σvM stress, transmitting greater stress to the cortical and medullary bone. CLINICAL RELEVANCE: The best stress distribution in PEEKc components may contribute to decreased stress shielding; in vitro and in vivo research is recommended to investigate this.

A new method of adhesive system application improves the bond strength between fiber post and root dentin.

This study evaluated a new method of adhesive system application on the bond strength between fiber post and root dentin using two adhesive systems. The canals of sixty bovine incisors were prepared and obturated. The roots were divided into six groups (n=10) according to the adhesive system (Clearfil SE - CSE and Single Bond Universal - SBU) and the application strategy (microbrush - MB; rotary brush - RB; and ultrasonic tip - US). The glass fiber posts were cemented with resin cement (RelyX ARC). The roots were sectioned perpendicularly to their long axis, and three slices per root were obtained. Previously to the push-out test, confocal laser scanning microscopy (CLSM) was performed to illustrate the interfacial adaptation of the cement to the root canal walls. Failure patterns were analyzed with 40x magnification. Shapiro-Wilk indicated a normal distribution of the data. The bond strength values were compared using one-way ANOVA and Tukey's tests. Student's T test analyzed the differences between the adhesive systems within each third and protocol. A significance level of 5% was used. CSE with RB showed higher mean bond strength values compared to MB (conventional technique) (P < 0.05). US application resulted in intermediate bond strength values for CSE (P > 0.05). The application of SBU using RB generated higher mean bond strength values compared to MB and US (P < 0.05). Adhesive failures were predominant (65.5%). CSE and SBU application with the new rotary brush improved the bond strength of fiber posts to root dentin compared to the conventional strategy.

The influence of filler load in 3D printing resin-based composites.

OBJECTIVE: To evaluate the influence of the barium glass (BG) filler in 3D printing resin-based composites for restorative structures. METHODS: Experimental 3D printing resin-based composites were formulated with UDMA 70%wt, Bis-EMA 20%wt, and TEGDMA 10%wt. Photoinitiators TPO and DFI (2%wt) were used. BG was incorporated at 40%wt and 50%wt. 0%wt BG was used as negative control and the VarseoSmile Crownplus (Bego) was used as a commercial control. Specimens were printed using a 3D printer. Subsequently, specimens were washed and submitted to post-curing with 405 nm at 60ºC for 2 × 20 min at FormCure (FormLabs). 3D printing resin-based composites were evaluated by flexural strength, degree of conversion, softening in solvent, radiopacity, and cytotoxicity against gingival fibroblasts. Data were statistically analyzed using one-way ANOVA (α = 0.05). RESULTS: No significant differences in flexural strength were showed between BG40% (90.5 ± 5,4 MPa), BG50% (102.0 ± 11.7 MPa) and VA (105.2 ± 11.7 MPa). Addition of 40% and 50% of BG showed no influence in the degree of conversion compared to VA (p > 0.05). All groups showed softening in solvent after immersion in ethanol (p < 0.05). All groups showed more than 1mmAl of radiopacity. BG50% showed significantly higher radiopacity (2.8 ± 0.3 mmAl) than other groups (p < 0,05). Cytotoxicity evaluation showed gingival cell viability higher than 80% for all groups. SIGNIFICANCE: Addition of up to 50%wt of barium glass in experimental 3D printing resin-based composites showed promising results for long-term restorative structures.

Novel Organic-Inorganic Nanocomposite Hybrids Based on Bioactive Glass Nanoparticles and Their Enhanced Osteoinductive Properties.

Inorganic-organic hybrid biomaterials have been proposed for bone tissue repair, with improved mechanical flexibility compared with scaffolds fabricated from bioceramics. However, obtaining hybrids with osteoinductive properties equivalent to those of bioceramics is still a challenge. In this work, we present for the first time the synthesis of a class II hybrid modified with bioactive glass nanoparticles (nBGs) with osteoinductive properties. The nanocomposite hybrids were produced by incorporating nBGs in situ into a polytetrahydrofuran (PTHF) and silica (SiO2) hybrid synthesis mixture using a combined sol-gel and cationic polymerization method. nBGs ~80 nm in size were synthesized using the sol-gel technique. The structure, composition, morphology, and mechanical properties of the resulting materials were characterized using ATR-FTIR, 29Si MAS NMR, SEM-EDX, AFM, TGA, DSC, mechanical, and DMA testing. The in vitro bioactivity and degradability of the hybrids were assessed in simulated body fluid (SBF) and PBS, respectively. Cytocompatibility with mesenchymal stem cells was assessed using MTS and cell adhesion assays. Osteogenic differentiation was determined using the alkaline phosphatase activity (ALP), as well as the gene expression of Runx2 and Osterix markers. Hybrids loaded with 5, 10, and 15% of nBGs retained the mechanical flexibility of the PTHF-SiO2 matrix and improved its ability to promote the formation of bone-like apatite in SBF. The nBGs did not impair cell viability, increased the ALP activity, and upregulated the expression of Runx2 and Osterix. These results demonstrate that nBGs are an effective osteoinductive nanoadditive for the production of class II hybrid materials with enhanced properties for bone tissue regeneration.

Novel Fe3O4 Nanoparticles with Bioactive Glass-Naproxen Coating: Synthesis, Characterization, and In Vitro Evaluation of Bioactivity.

Immune response to biomaterials, which is intimately related to their surface properties, can produce chronic inflammation and fibrosis, leading to implant failure. This study investigated the development of magnetic nanoparticles coated with silica and incorporating the anti-inflammatory drug naproxen, aimed at multifunctional biomedical applications. The synthesized nanoparticles were characterized using various techniques that confirmed the presence of magnetite and the formation of a silica-rich bioactive glass (BG) layer. In vitro studies demonstrated that the nanoparticles exhibited bioactive properties, forming an apatite surface layer when immersed in simulated body fluid, and biocompatibility with bone cells, with good viability and alkaline phosphatase activity. Naproxen, either free or encapsulated, reduced nitric oxide production, an inflammatory marker, while the BG coating alone did not show anti-inflammatory effects in this study. Overall, the magnetic nanoparticles coated with BG and naproxen showed promise for biomedical applications, especially anti-inflammatory activity in macrophages and in the bone field, due to their biocompatibility, bioactivity, and osteogenic potential.

Development and characterization of ceramic-polymeric hybrid scaffolds for bone regeneration: incorporating of bioactive glass BG-58S into PDLLA matrix.

In recent years, there has been a notable surge of interest in hybrid materials within the biomedical field, particularly for applications in bone repair and regeneration. Ceramic-polymeric hybrid scaffolds have shown promising outcomes. This study aimed to synthesize bioactive glass (BG-58S) for integration into a bioresorbable polymeric matrix based on PDLLA, aiming to create a bioactive scaffold featuring stable pH levels. The synthesis involved a thermally induced phase separation process followed by lyophilization to ensure an appropriate porous structure. BG-58S characterization revealed vitreous, bioactive, and mesoporous structural properties. The scaffolds were analyzed for morphology, interconnectivity, chemical groups, porosity and pore size distribution, zeta potential, pH, in vitro degradation, as well as cell viability tests, total protein content and mineralization nodule production. The PDLLA scaffold displayed a homogeneous morphology with interconnected macropores, while the hybrid scaffold exhibited a heterogeneous morphology with smaller diameter pores due to BG-58S filling. The hybrid scaffold also demonstrated a pH buffering effect on the polymer surface. In addition to structural characteristics, degradation tests indicated that by incorporating BG-58S modified the acidic degradation of the polymer, allowing for increased total protein production and the formation of mineralization nodules, indicating a positive influence on cell culture.

Vidrios bioactivos en endodoncia. Revisión narrativa de sus propiedades biológicas / Bioactive glasess in endodontics. A narrative review about their biological properties

Los vidrios bioactivos (VBa) son materiales biocerámicos que tienen una extensa aplicación en medicina y odontología. A causa de su contenido de calcio y fosfato son muy simi- lares a la hidroxiapatita del tejido óseo. Su biocompatibili- dad y bioactividad los hacen materiales muy útiles para ser aplicados en diferentes áreas de la práctica dental, tales como periodoncia, cirugía, odontología restauradora y endodoncia. En endodoncia los VBa están indicados para realizar protec- ciones pulpares directas, pulpotomías, desinfecciones y obtu- raciones del sistema de conductos radiculares. El objetivo del presente trabajo fue realizar una revisión de las propiedades biológicas de los VBa en relación a sus aplicaciones en en- dodoncia (AU)

Bioactive glasses (BGs) are bioceramic materials with extensive clinical applications in medicine and dentistry. Be- cause of their phosphate and calcium contents, they are like the hydroxyapatiteof bone tissue. Their biocompatibility and bioactivity make them very useful biomaterials in different areas of dental practice, such as periodontics, oral surgery, restorative dentistry, and endodontics. In endodontics, bioac- tive glasses are indicated for direct pulp capping, pulpoto- mies, disinfections and fillings of the root canal system. The aim of this work was to carry out a review of the biological properties of BGs in relation to its application in endodontics (AU)

Comparative analysis of the biomechanical behavior of the maxillary central incisors restored with glass fiber post and cast metal post and core submitted to orthodontic forces: A study with finite elements.

INTRODUCTION: Different types of intraradicular restorations and their insertion have an impact on teeth biomechanics. This study aimed to analyze the biomechanical behavior of maxillary central incisors restored with glass fiber post (GFP) and cast metal post and core (CMP) subjected to buccolingual and mesiodistal orthodontic forces using the finite element method. METHODS: Two models of the maxillary central incisor with periodontal ligament, cortical bone, and trabecular bone were made. One of the models included intraradicular restoration with GFP, whereas, in the other, the incisor was restored with CMP. After creating the tridimensional mesh of finite elements, applying 2 orthodontic forces were simulated: 65 g of buccolingual force and 70 g of mesiodistal force. The forces were applied parallel to the palatal plane in the region of the bracket slot, located 4 mm to the incisal edge. RESULTS: The maximum stresses generated in the GFP-restored root were 3.642 × 10-1 MPa and 4.755 × 10-1 MPa from the buccolingual and mesiodistal forces, respectively. Likewise, the stresses in the CMP restored root were 2.777 × 10-1MPa and 3.826 × 10-1MPa. The radicular area with higher stress on both models was located in the cervical third: on the buccal surface when the buccolingual force was applied and on the mesial surface when the mesiodistal force was applied. The highest stress levels were found on the CMP structure. CONCLUSIONS: The incisor restored with cast metal post revealed lower stress values transferred to the root than the one restored with GFP. The stresses on the structure of the GFP were lower and more homogeneous than the ones found on the cast metal post. The difference among the stress values in the materials is within a safe margin for using both materials in relation to orthodontic forces.

Effects of glass-ceramic produced by the sol-gel route in macrophages recruitment and polarization into bone tissue regeneration.

Effective bone substitute biomaterials remain an important challenge in patients with large bone defects. Glass ceramics produced by different synthesis routes may result in changes in the material physicochemical properties and consequently affect the success or failure of the bone healing response. To investigate the differences in the orchestration of the inflammatory and healing process in bone grafting and repair using different glass-ceramic routes production. Thirty male Wistar rats underwent surgical unilateral parietal defects filled with silicate glass-ceramic produced by distinct routes: BS - particulate glass-ceramic produced via the fusion/solidification route, and BG - particulate glass-ceramic produced via the sol-gel route. After 7, 14, and 21 days from biomaterial grafting, parietal bones were removed to be analyzed under H&E and Massons' Trichome staining, and immunohistochemistry for CD206, iNOS, and TGF-ß. Our findings demonstrated that the density of lymphocytes and plasma cells was significantly higher in the BS group at 45, and 7 days compared to the BG group, respectively. Furthermore, a significant increase of foreign body giant cells (FBGCs) in the BG group at day 7, compared to BS was found, demonstrating early efficient recruitment of FBGCs against sol-gel-derived glass-ceramic particulate (BS group). According to macrophage profiles, CD206+ macrophages enhanced at the final periods of both groups, being significantly higher at 45 days of BS compared to the BG group. On the other hand, the density of transformation growth factor beta (TGF-ß) positive cells on 21 days were the highest in BG, and the lowest in the BS group, demonstrating a differential synergy among groups. Noteworthy, TGF-ß+ cells were significantly higher at 21 days of BG compared to the BS group. Glass-ceramic biomaterials can act differently in the biological process of bone remodeling due to their route production, being the sol-gel route more efficient to activate M2 macrophages and specific FBGCs compared to the traditional route. Altogether, these features lead to a better understanding of the effectiveness of inflammatory response for biomaterial degradation and provide new insights for further preclinical and clinical studies involved in bone healing.