Strontium-containing mineralized phospholipid coatings improve osseointegration in osteoporotic rats.

Surface treatments play an important role in enhancing the osseointegration of Titanium (Ti) and its alloys. This study introduces a method employing biomimetic hydroxyapatite (Hap) deposition guided by molecularly organized phospholipids, affixed to the metal implant surface. Using the Langmuir-Blodgett technique, phospholipids were deposited onto Ti-screws by using CaCl2 or CaCl2/SrCl2 aqueous solution in the subphase of a Langmuir trough in the target proportion (i.e. 10 and 90 mol% of Sr2+ in relation of Ca2+) followed by immersion in phosphate buffer and in supersaturated simulated body fluid. Coating composition and morphology were evaluated using infrared spectroscopy and scanning electron microscopy, respectively, while contact angle measurements assessed coating wettability and surface energy. Randomized screws were then implanted into the tibias of healthy and osteoporotic female rats (G1: Control-Machined, G2: Hap, G3: HapSr10, G4: HapSr90). Osseointegration, assessed 60 days post-implantation, included reverse torque, fluorochrome area, bone tissue-screw contact area, and linear extent of bone-screw contact. Results, grouped by surface treatment (Machined, Hap, HapSr10, HapSr90), revealed that the deposition of Hap, HapSr10, and HapSr90 resulted in thin and rough coatings composed of hydroxyapatite (Hap) on the screw surface with nanoscale pores. The coatings resulted in increased wettability and surface energy of Ti surfaces. The minerals are chemically similar to natural bone apatite as revealed by FTIR analysis. In vivo analyses indicated higher torque values for strontium-containing surfaces in the osteoporotic group (p = 0.02) and, in the control group superior torque for screw removal on the Hap surface (p = 0.023). Hydroxyapatite-treated surfaces enhance morphology, composition, and reactivity, promoting screw osseointegration in healthy and osteoporotic female rats. The incorporation of strontium into the mineral phase has been proposed to not only stimulate osteoblast activity but also reduce osteoclastic resorption, which may explain the improved outcomes observed here in experimental osteoporotic conditions.

Bone Tissue Engineering With Chitosan, Carbon Nanotubes, and Hydroxyapatite Biomaterials Enriched With Mesenchymal Stem Cells: A Radiographic and Histological Evaluation in a Sheep Model Undergoing Ostectomy (Bone Tissue Engineering in a Sheep Model).

Comminuted fractures associated with tissue loss can adversely affect bone regeneration. Biomaterials enriched with mesenchymal stem cells (MSCs) employed for supporting osteosynthesis and potentiating osteoconduction are necessary to fill these bone defects. Natural compound biomaterials, similar to bone tissue, have been extensively tested in animal models for clinical use. Bone tissue engineering studies have used critical-size defects in ovine tibia monitored by imaging and histological examinations to evaluate the regenerative process. This study aimed to monitor the regenerative process in ovine tibial defects with or without chitosan, carbon nanotubes, or hydroxyapatite biomaterials, enriched or not enriched with MSCs. A 3-cm ostectomy was performed in 18 female Suffolk sheep. A 10-hole 4.5 mm narrow locking compression plate was used for osteosynthesis. The animals were randomly divided into three groups (n = 6): control (CON); defects filled with chitosan, carbon nanotubes, and hydroxyapatite biomaterial (BIO); and the same biomaterial enriched with bone marrow MSCs (BIO + CELL). The animals were evaluated monthly using radiographic examinations until 90 postoperative days, when they were euthanized. The limbs were subjected to micro-computed tomography (micro-CT), and bone specimens were subjected to histological evaluations. The radiographic examinations revealed construction stability without plate deviation, fracture, or bone lysis. Micro-CT evaluation demonstrated a difference in bone microarchitecture between the CON and biomaterial treatment groups (BIO and BIO + CELL). In the histological evaluations, the CON group did not demonstrate bone formation, and in the treatment groups (BIO and BIO + CELL), biocompatibility with sheep tissue was noted, and bone formation with trabeculae interspersed with remnants of the biomaterial was observed, with no differences between the groups. In conclusion, biomaterials present osteoconduction with beneficial characteristics for filling bone-lost fractures, and MSCs did not interfere with bone formation.

Biological interaction of bioactive polymeric membranes in induced bone defects in rabbit tibias.

The study aimed to evaluate bone repair using three osteoinductive polymers in bone defects created in rabbit tibias. Forty-eight adult rabbits were assessed at various time points: three, seven, fourteen, and thirty days. The groups included a control group (without biomaterial), M1 (Poly L Lactide co Polycaprolactone/Polyethylene Glycol), M2 (Poly L Lactide co Polycaprolactone/Polyethylene Glycol/ß-Tricalcium Phosphate), and M3 (Poly L Lactide co Polycaprolactone/Polyethylene Glycol/nano hydroxyapatite). Histomorphometric analysis was conducted to evaluate new bone formation within and around the bone defect. At 14 (p<0.05) and 30 days (p<0.05), the callus area in the membrane groups, particularly in M3, was also significantly larger than in the control group, indicating the osteoinductive potential of these biomaterials. The callus consisted of both bone and cartilaginous matrix, suggesting a robust activation of endochondral ossification. The number of osteoclast was higher in the membrane groups, especially at 14 days in the M3 group, indicating increased bone remodeling activity. The membranes were not fully absorbed by 30 days, creating a space between the defect and the periosteum. In conclusion, all three membranes showed significant chondro and osteoinductive potential, with the membrane containing nano-hydroxyapatite demonstrating the most pronounced potential.

Bone regeneration by a bone substitute biomaterial containing hydroxyapatite, chitosan, xanthan and graphene oxide supplemented with conditioned medium from mesenchymal stem cells.

This study analyzed a recently developed bone substitute biomaterial made of chitosan-xanthanhydroxyapatite-graphene oxide (CXHAG). The CXHAG particles underwent in vitro structural and morphological characterization, and in vivo testing with or without osteogenic conditioned medium from mesenchymal stem cells. Aim: The aim of this study was to determine whether the CXHAG novel biomaterial, supplemented with conditioned medium from mesenchymal stem cells, could be useful for bone regeneration. Materials and Method: For the in vitro study, cells were incubated with 20mg of CXHAG granules for 24 hours and a MTT assay was performed to tests for cytotoxicity. For the in vivo study, critical size calvarial bone defects were created in twenty-five rats. One animal had the defect unfilled (Control Group-CG) and was euthanized after 42 days. Twelve rats received the CXHAG particles (Group 1-G1) and the other twelve received the CXHAG particles supplemented with the conditioned medium (Group 2-G2). All G1/G2 grafts were covered with a CXHAG membrane. G1/G2 animals were euthanized after 14 days (T1) or 42 days (T2). The specimens were processed and histologically evaluated. Results: SEM analysis of the CXHAG particles showed granules of 300-400µm, with a rough irregular surface. They were not cytotoxic to dental pulp stem cells in vitro. The CG specimen showed loose immature connective tissue and no bone formation at the center of the defect. G1 and G2 presented remnant biomaterial particles at both time points, but only G2 had bone formation at the enter of the defect. Conclusions: The conditioned medium had a positive effect on bone regeneration in rat calvarial critical size defects when associated with the novel bone substitute biomaterial.

Este estudo analisou um biomaterial substituto ósseo recentemente desenvolvido feito de óxido de quitosana-xantana-hidroxiapatita-grafeno (CXHAG). As partículas CXHAG observaram caracterização estrutural e morfológica in vitro. Foi testado in vivo, com ou sem meio condicionado osteogênico de células-tronco mesenquimais. Objetivo: O objetivo deste estudo foi determinar se o novo biomaterial CXHAG, suplementado com meio condicionado de células-tronco mesenquimais, poderia ser útil para a regeneração óssea. Materiais e Método: Para o estudo in vitro, as células foram incubadas com 20mg de grânulos de CXHAG por 24 horas e foi realizado ensaio de MTT para verificar a citotoxicidade. Para o estudo in vivo, foram criados defeitos ósseos de tamanho crítico na calvária em vinte e cinco ratos. Um animal teve o defeito não preenchido (Grupo Controle ­ GC) e foi eutanasiado após 42 dias. Doze ratos receberam as partículas CXHAG (Grupo 1 ­ G1) e os outros doze receberam as partículas CXHAG suplementadas com o meio condicionado (Grupo 2 ­ G2). Todos os enxertos G1/G2 foram cobertos com membrana CXHAG. Os animais do G1/G2 foram eutanasiados após 14 dias (T1) ou 42 dias (T2). Os espécimes foram processados e avaliados histologicamente. Resultados: A análise SEM das partículas CXHAG mostrou grânulos de 300-400µm, com superfície áspera e irregular. Eles não foram citotóxicos para células-tronco da polpa dentária in vitro. As amostras CG mostraram tecido conjuntivo imaturo frouxo e nenhuma formação óssea no centro do defeito. G1 e G2 apresentaram partículas remanescentes de biomateriais em ambos os momentos, mas apenas G2 apresentou formação óssea no centro do defeito. Conclusões: O meio condicionado teve repercussões positivas na regeneração óssea em defeitos críticos de calvária de ratos quando associado ao novo biomaterial substituto ósseo.

Magnesium-Doped Hydroxyapatite Nanofibers for Medicine Applications: Characterization, Antimicrobial Activity, and Cytotoxicity Study.

Magnesium-doped hydroxyapatite (HAp-Mg) nanofibers show promise for medical applications due to their structural similarity to bone minerals and enhanced biological properties, such as improved biocompatibility and antimicrobial activity. This study synthesized HAp-Mg nanofibers using a microwave-assisted hydrothermal method (MAHM) to evaluate their cytotoxicity, biocompatibility, and antimicrobial efficacy compared to commercial hydroxyapatite (HAp). Characterization through X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR) confirmed the successful incorporation of magnesium, producing high-purity, crystalline nanofibers with hexagonal morphology. Rietveld refinement showed slight lattice parameter shortening, indicating Mg2+ ion integration. Cell viability assays (MTT and AlamarBlue) revealed a significant increase in fibroblast proliferation with 2% and 5% HAp-Mg concentrations compared to controls (p < 0.05), demonstrating non-cytotoxicity and enhanced biocompatibility. Antimicrobial tests (disk diffusion method, 100 µg/mL) showed that HAp-Mg had strong antibacterial effects against Gram-positive and Gram-negative bacteria and moderate antifungal activity against Candida albicans. In contrast, commercial HAp showed no antimicrobial effects. These results suggest HAp-Mg nanofibers have significant advantages as biomaterials for medical applications, particularly in preventing implant-related infections and supporting further clinical development.

Effect of laser photobiomodulation combined with hydroxyapatite nanoparticles on the osteogenic differentiation of mesenchymal stem cells using artificial intelligence: An in vitro study.

AIM: To evaluate in vitro the effect of laser photobiomodulation (PBM) combined or not with 30-nm hydroxyapatite nanoparticles (HANp), on the osteogenic differentiation of human umbilical cord mesenchymal stem cells (hUC-MSCs) by morphometric analysis using artificial intelligence programs (TensorFlow and ArcGIS). METHODS: UC-MSCs were isolated and cultured until 80% confluence was reached. The cells were then plated according to the following experimental groups: G1 -control (DMEM), G2 -BMP-2, G3 -BMP-7, G4 -PBM (660 nm, 10 mW, 2.5 J/cm2, spot size of 0.08 cm2), G5 -HANp, G6 -HANp + PBM, G7 -BMP-2 + PBM, and G8 -BMP-7 + PBM. The MTT assay was used to analyze cell viability at 24, 48 and 72 h. Osteogenic differentiation was assessed by Alizarin Red staining after 7, 14 and 21 days. For morphometric analysis, areas of osteogenic differentiation (pixel2) were delimited by machine learning using the TensorFlow and ArcGIS 10.8 programs. RESULTS: The results of the MTT assay showed high rates of cell viability and proliferation in all groups when compared to control. Morphometric analysis revealed a greater area of osteogenic differentiation in G5 (HANp = 142709,33±36573,39) and G6 (HANp + PBM = 125452,00±24226,95) at all time points evaluated. CONCLUSION: It is suggested that HANp, whether combined with PBM or not, may be a promising alternative to enhance the cellular viability and osteogenic differentiation of hUC-MSCs.

Effect of an experimental desensitizer with a hydroxyapatite-capsaicin composite applied before in-office dental bleaching on hydrogen peroxide diffusion, color and surface changes.

OBJECTIVE: To evaluate a prior application of an experimental desensitizer containing a hydroxyapatite-capsaicin composite (HAp-CAP) in different concentrations on hydrogen peroxide (HP) diffusion into the pulp chamber, bleaching efficacy (BE) and on physical and chemical alterations of the enamel surface after in-office bleaching. MATERIALS AND METHODS: Forty sound premolars were randomized in five groups according to each experimental condition (n = 8): no bleaching (negative control), only bleaching (positive control), 0.1%, 1% and 5% of HAp-CAP. Four groups were submitted to in-office bleaching (HP 35%) post-desensitizer application. The HP concentration (µg/mL) on the pulp chamber was measured by UV-Vis spectrophotometer. The BE was measured by digital spectrophotometer (ΔEab, ΔE00 and ΔWID) before and after 7 days bleaching. Enamel tooth fragments obtained from twenty molars were submitted to the same experimental conditions and analyzed using FE-SEM and EDS, Vickers microhardness (VHN), Raman spectroscopy, and nanoroughness (Ra) by AFM to evaluate morphologic and chemical changes on enamel surface. All data were submitted to statistical analysis (α = 0.05). RESULTS: The groups treated with HAp-CAP exhibited a lower concentration of HP in the pulp chamber compared to only bleaching group (p < 0.05). There were no significant differences observed in BE between HAp-CAP groups and only bleaching group (p > 0.05). Only HAp-CAP 5% showed no significant differences in VHN values when compared to no bleaching group (p > 0.05). There were no significant differences among any group in Ra values (p > 0.05). The groups submitted to HAp-CAP showed a higher mineral concentration when compared to only bleaching group (p < 0.05). CONCLUSION: Desensitizers containing HAp-CAP up to 5% effectively reduce HP diffusion into the pulp chamber after in-office bleaching, without interfering to BE and Ra, as well as prevent enamel demineralization. CLINICAL RELEVANCE: The use of desensitizers containing HAp-CAP during in-office bleaching treatments offers a promising approach to reduce the risk of pulp irritation caused by hydrogen peroxide diffusion, without compromising the bleaching effectiveness or causing surface roughness.

Extraction of bio-hydroxyapatite from devilfish (Loricariidae) for the fluoride and cadmium adsorption from water and its feasible photocatalytic properties.

In this study, the adsorption capacity of bio-hydroxyapatite (Bio-HAp) from devilfish for the removal of F- and Cd(II) from aqueous solutions was investigated. This material was synthesized according to a 2FI factorial experimental design by varying the extraction conditions for Bio-HAp, including the type of pretreatment (alkaline and peroxide), the calcination temperature from 550 to 850 °C, and the sonication process. The maximum adsorption capacities were 8.48 and 83.56 mg g-1 for F- and Cd(II), respectively. Statistical analysis showed the importance of the type of pretreatment, temperature, and sonication for adsorption. The predicted optimal conditions were Bio-HAp extracted from bone with peroxide pretreatment, calcination at 550 °C and sonication. The surface of the Bio-HAp was found to be mesoporous and basic in character. TGA, FT-IR and SEM-EDS characterizations confirmed the presence of F- and Cd(II) on the Bio-HAp surface and confirmed the adsorption mechanisms by electrostatic forces, ion exchange, and chemisorption. The Praunitz-Rake model of adsorption isotherm showed better agreement with the equilibrium adsorption data of F- and Cd(II) at pH 7. Furthermore, photodegradation experiments showed 100% degradation methylene blue (MB) under natural sunlight. This study indicates an effective photodegradation process, suggesting high adsorption capacity of the samples. The use of devilfish as an adsorbent promises to be a viable and sustainable option for the removal of fluoride and cadmium from water, and for use in photodegradation experiments.

Tomographic and Electron Microscopy Description of Two Bone-Substitute Xenografts for the Preservation of Dental Alveoli.

After tooth extraction, bone levels in the alveoli decrease. Using a bone substitute can help minimize this bone loss. The substitute can be sourced from a human or animal donor or synthetically prepared. In this study, we aimed to address the following PICOS question: In patients needing dental alveolar preservation for implant placement, how does alveolar preservation using a bovine hydroxyapatite bone xenograft with collagen compare to a xenograft without collagen in terms of changes in alveolar height and width, bone density, and the characteristics of the bone tissue observed in biopsies taken at 6 months? We evaluated two xenograft-type bone substitutes for preserving post-extraction dental sockets using tomography and microscopy to answer that question. A total of 18 dental alveoli were studied: 11 preserved with a xenograft composed of apatite (InterOss) and 7 with a xenograft composed of apatite-collagen (InterOss Collagen). Tomographic controls were performed at 1 and 6 months, and microscopic studies were performed on 13 samples. The biopsies were examined with scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). A Multivariate Analysis of Variance (MANOVA) was conducted in the statistical analysis, revealing a significant increase in bone density over time (p = 0.04). Specifically, bone density increased from an average of 526.14 HU at 30 days to 721.96 HU at 60 days in collagen-free samples. However, no statistically significant differences in height or width were found between groups. The MANOVA results indicated that the overall model had a low predictive ability for height, width, and density variables (R-squared values were low), likely due to sample size limitations and the complexity of bone tissue dynamics. On the other hand, FTIR analysis revealed the presence of phosphate groups, carbonates, and amides I, II, and III, indicative of inorganic (hydroxyapatite) and organic (type I collagen) materials in the xenografts. TGA and DSC showed high thermal stability, with minimal mass loss below 150 °C. Finally, both xenografts were influential in alveolar bone regeneration after extraction without significant differences. The trend of increasing collagen density suggests an effect that requires further investigation. However, it is recommended that the sample size be increased to enhance the validity of the results.

Implications of Histological and Ultrastructural Characteristics on the Chemical and Mechanical Properties of Hypomineralised Enamel and Clinical Consequences.

Molar incisor hypomineralisation (MIH) is a qualitative type of enamel defect, which occurs due to a failure in the biomineralisation process of the enamel organic matrix during amelogenesis. The tooth enamel affected by MIH shows changes in its chemical, structural, and mechanical properties, leading to different clinical repercussions. The color of MIH opacities varies from opaque white to yellow/brown, and elemental analyses of these lesions show a lower calcium and phosphate content, minerals that are more abundant in sound enamel. Furthermore, the incorporation of other molecules occurs, such as carbonate, a component that provides a greater degree of solubility, thus making hypomineralised enamel more susceptible to posteruptive fractures. At a structural level, the layer of hydroxyapatite crystals appears to be disorganized, with morphological changes, implying a greater degree of porosity in the structure. The increase in porosity of the structure may be associated with dental hypersensitivity, a common clinical repercussion among patients with MIH. Among the mechanical properties, a decrease in hardness and modulus of elasticity occurs, and this also makes the enamel more fragile. Deficiency in biomineralisation can be caused by changes in the function of ameloblasts or by failures at the intercellular junction that result in lower activity of proteases such as MMP-20 and KLK4. The increase in proteins in the organic matrix of enamel impairs the growth and incorporation of minerals into the hydroxyapatite crystals, so that the enamel becomes hypomineralised and has larger organic content, thus having an impact on its properties. These changes present in the enamel with MIH help to explain the clinical repercussions caused by this condition.

Extraction and Physicochemical Characterization of Hydroxyapatites From Horse Humerus Bones of Different Ages (1, 3, 6, and 8 Years old) Calcined at Low Temperature.

The aim of this work is to investigate the changes in the physicochemical properties of hydroxyapatite (HAp) extracted from horse humerus bones of different ages (1, 3, 6, and 8 years) subjected to low temperature calcination (600°C). Thermal analysis revealed significant mass loss due to water, collagen, organic compounds, carbonates, and age-related magnesium out-diffusion. Higher fat content in older bones contributed to increased mass loss. Phosphorus content remained constant across age groups, while calcium and sodium showed age-related fluctuations. Magnesium levels decreased with age, emphasizing its importance for early bone development. The Ca/P ratio deviated from the stoichiometric values due to additional ions from biogenic sources. Infrared spectroscopy identified functional groups in carbonated HAp, with changes observed before and after calcination. The full width at half maximum (FWHM) of the 961 cm-1 band decreased with age, indicating improved crystalline quality. The molar absorption coefficients provided information on the changes in molecular concentration and emphasized the differences between the age groups. X-ray analysis revealed nanocrystalline HAp in all samples, with crystallite size increasing with age. Rietveld analysis showed that the lattice parameters were affected by the presence of organic material, but the lattice constants remained stable, confirming high crystallinity independent of age. TEM analysis confirmed nanocrystalline structures, with crystallite size increasing with age. SEM images showed the characteristic porosity of calcined HAp, with particle size correlating positively with age. Calcination at 600°C preserved the nanoscale properties and microcrystal formation. Raman spectroscopy confirmed the identity of HAp, with FWHM variations indicating age-related changes in crystalline quality. EHAp1 showed increased FWHM, indicating lower crystalline quality and increased trace element content.

Synthetic Bone Blocks Produced by Additive Manufacturing in the Repair of Critical Bone Defects.

This study evaluated the efficacy of synthetic bone blocks, composed of hydroxyapatite (HA) or ß-tricalcium phosphate (B-TCP), which were produced by additive manufacturing and used for the repair of critical size bone defects (CSDs) in rat calvaria. Sixty rats were divided into five groups (n = 12): blood clot (CONTROL), 3D-printed HA (HA), 3D-printed ß-TCP (B-TCP), 3D-printed HA + autologous micrograft (HA+RIG), and 3D-printed ß-TCP + autologous micrograft (B-TCP+RIG). CSDs were surgically created in the parietal bone and treated with the respective biomaterials. The animals were euthanized at 30 and 60 days postsurgery for microcomputed tomography (micro-CT) histomorphometric, and immunohistochemical analysis to assess new bone formation. Micro-CT analysis showed that both biomaterials were incorporated into the animals' calvaria. The HA+RIG group, especially at 60 days, exhibited a significant increase in bone formation compared with the control. The use of 3D-printed bioceramics resulted in thinner trabeculae but a higher number of trabeculae compared with the control. Histomorphometric analysis showed bone islands in close contact with the B-TCP and HA blocks at 30 days. The HA blocks (HA and HA+RIG groups) showed statistically higher new bone formation values with further improvement when autologous micrografts were included. Immunohistochemical analysis showed the expression of bone repair proteins. At 30 days, the HA+RIG group had moderate Osteopontin (OPN) staining, indicating that the repair process had started, whereas other groups showed no staining. At 60 days, the HA+RIG group showed slight staining, similar to that of the control. Osteocalcin (OCN) staining, indicating osteoblastic activity, showed moderate expression in the HA and HA+RIG groups at 30 days, with slight expression in the B-TCP and B-TCP+RIG groups. The combination of HA blocks with autologous micrografts significantly enhanced bone repair, suggesting that the presence of progenitor cells and growth factors in the micrografts contributed to the improved outcomes. It was concluded that 3D-printed bone substitute blocks, associated with autologous micrografts, are highly effective in promoting bone repair in CSDs in rat calvaria.

Synthesis and characterization of different nano-hydroxyapatites and their impact on dental enamel following topical application for dental bleaching.

OBJECTIVE: This study aims to synthesize, characterize, and assess the penetration of hydrogen peroxide (HP), color change (CC), and surface morphology changes after the application of two distinct nano-hydroxyapatite (nano-HAp). METHODS: Two nano-HAp were previously synthesized by co-precipitation: one with rod-shaped particles (RS) and the other with spherical-shaped particles (SS). The surface charge of the nano-HAp particles was determined at varying pH levels and characterized by X-ray diffraction patterns and Fourier transform infrared spectroscopy. The morphology of the samples was assessed using scanning electron microscopy (SEM). The nano-HAp particles were applied before the dental bleaching procedure. Forty teeth were divided into four groups (n = 10) according to the bleaching treatment: no treatment, bleaching with 35 % HP only, RS application and bleaching with 35 % HP, and SS application and bleaching with 35 % HP. HP concentration (µg mL-1) was measured using UV-Vis, while CC was evaluated with a digital spectrophotometer (ΔEab, ΔE00 and WID). Additionally, four teeth from each group were selected for SEM analysis. Statistical analysis encompassed one-way ANOVA, Tukey's, and Dunnet's tests. RESULTS: RS and SS were successfully synthesized by coprecipitation, primarily differing in pH during synthesis. Both variations of nano-HAp morphology significantly reduced HP diffusion into the pulp chamber (p < 0.001). Regarding enamel morphology, groups analyzed post dental bleaching exhibited greater HAp deposition on the enamel surface. Notably, this deposition did not impede CC. SIGNIFICANCE: The utilization of different nano-HAp morphologies prior to dental bleaching appears to be a promising strategy for mitigating adverse effects associated with dental bleaching procedures.

Are we approaching the development of a novel calcium phosphate-based bioceramic dental material?

OBJECTIVES: Develop a sustainable bovine hydroxyapatite dental ceramic with the addition of titanium dioxide (TiO2) nanoparticles (5 % and 8 % by weight), analyzing the outcome of this addition to the microstructure, as well as its mechanical and chemical properties, in order to evaluate whether they satisfy the International Organization for Standardization (ISO) 6872:2015 for dental ceramics or not. METHODS: Disks were obtained through uniaxial followed by isostatic pressing from bovine hydroxyapatite powder and TiO2 nanoparticles and sintered at 1300ºC for 2 h. Three experimental groups were developed (HA, HA+5 %TiO2 and HA+8 %TiO2) and subjected to X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), indentation fracture (IF), biaxial flexural strength (BFS) and chemical solubility test. RESULTS: XRD revealed, for HA group, the appearance of a peak corresponding to b-tricalcium phosphate (ß-TCP). For HA+ 5 %TiO2 and HA+ 8 %TiO2, the entire composition was converted into ß-TCP and calcium titanate (CaTiO3). The SEM images showed a dense ceramic matrix and a uniform distribution of another phase in groups with TiO2 nanoparticles. HA+ 5 %TiO2 (1.40 ± 0.18 MPa.m1/2) and HA+ 8 %TiO2 (1.32 ± 0.18 MPa.m1/2) showed significantly higher fracture toughness values than HA (0.67 ± 0.09 MPa.m1/2). HA showed significantly higher characteristic stress (295.8 MPa) in comparison to groups with 5 % (235.1 MPa) and 8 % (214.4 MPa) TiO2 nanoparticles. Differences were not observed between the Weibull modulus values. The solubility results indicated that all experimental ceramics were above the 2000 ug/cm2 limit set by the ISO 6872:2015. SIGNIFICANCE: This study proposed the development and characterization of a new ceramic for dental prosthesis made from HA extracted from bovine bones, with the intention of reusing these solids waste and transforming them into a sustainable and low-cost material. Although the experimental calcium phosphate ceramic with additions of 5 % and 8 % of TiO2 achieved desirable mechanical properties, the chemical solubility values were very high.

Osteoconductive composite membranes produced by rotary jet spinning bioresorbable PLGA for bone regeneration.

Bone defects and injuries are common, and better solutions are needed for improved regeneration and osseointegration. Bioresorbable membranes hold great potential in bone tissue engineering due to their high surface area and versatility. In this context, polymers such as poly(lactic-co-glycolic acid) (PLGA) can be combined with osteoconductive materials like hydroxyapatite (HA) nanoparticles (NPs) to create membranes with enhanced bioactivity and bone regeneration. Rotary Jet spinning (RJS) is a powerful technique to produce these composite membranes. This study presents an innovative and efficient method to obtain PLGA-HA(NPs) membranes with continuous fibers containing homogeneous HA(NPs) distribution. The membranes demonstrated stable thermal degradation, allowing HA(NPs) quantification. In addition, the PLGA-HA(NPs) presented osteoconductivity, were not cytotoxic, and had high cell adhesion when cultured with pre-osteoblastic cells. These findings demonstrate the potential of RJS to produce PLGA-HA(NPs) membranes for easy and effective application in bone regeneration.

Supraperiosteal technique protocol for forehead filling with a mixture of calcium hydroxyapatite and hyaluronic acid: Double-blind, randomized controlled clinical trial.

OBJECTIVE: The current study aims to investigate the safety and efficacy of using calcium hydroxyapatite (CaHA) versus CaHA associated with hyaluronic acid (HA) for forehead volume replacement and contour restoration without forehead irregularities. METHODS: This interventional study involved 132 participants in a two-arm, parallel, double-blind trial for forehead treatment using the supraperiosteal technique. Group A received CaHA, and Group B received a combination of CaHA and HA as filler materials. Follow-up assessments occurred at 30 and 180 days, incorporating the 5-point Global Aesthetic Improvement Scale (GAIS) and photographic analysis for forehead volume replacement, contour restoration, and without forehead irregularities. Safety assessments included monitoring adverse events, particularly nodules. RESULTS: The study included all 132 enrolled patients who completed the trial. Applying CaHA in combination with HA resulted in a statistically significant improvement in both GAIS scale scores and the reduction of forehead irregularities. The total incidence of nodules was 3.7%. Group A had four times more occurrences of nodules than Group B. Furthermore, Group B exhibited lower rates of forehead irregularities following the treatment compared to Group A. CONCLUSION: The supraperiosteal application of CaHA and HA for forehead treatment demonstrates superior efficacy in addressing signs of aging compared to the isolated use of CaHA.

Design and simulation of scaffolds with lattice microstructures for bioprinting bone tissue.

BACKGROUND: Tissue engineering seeks to improve, maintain, or replace the biological functions of damaged organs or tissues with biological substitutes such as the development of scaffolds. In the case of bone tissue, they must have excellent mechanical properties like native bone. OBJECTIVE: In this work, three geometric models were designed for scaffolds with different structure lattices and porosity that could be biomechanically suitable and support cell growth for trabecular bone replacement applications in tissue engineering and regenerative medicine to the proximal femur area. METHODS: Geometries were designed using computer-aided design (CAD) software and evaluated using finite element analysis in compression tests. Three loads were considered according to the daily activity: 1177 N for slow walking, 2060 N for fast walking, and 245.25 N for a person in a bipedal position. All these loads for an adult weight of 75 kg. For each of them, three biomaterials were assigned: two polymers (poly-glycolic acid (PGA) and poly-lactic acid (PLA)) and one mineral (hydroxyapatite (HA)). 54 tests were performed: 27 for each of the tests. RESULTS: The results showed Young's modulus (E) between 1 and 4 GPa. CONCLUSION: If the resultant E is in the range of 0.1 to 5 GPa, the biomaterial is considered an appropriate alternative for the trabecular bone which is the main component of the proximal bone. However, for the models applied in this study, the best option is the poly-lactic acid which will allow absorbing the acting loads.

Effect of pH on hydroxyapatite coatings obtained by spray pyrolysis and their use as matrices for antibiotic adsorption by spin coating and release properties.

Calcium phosphate materials, particularly hydroxyapatite (HA), are extensively used in biomedical applications because of their prominence as primary inorganic constituents of human hard tissues. This study investigates the synthesis of HA coatings via spray pyrolysis using various precursors, including HA derived from bovine bone. The effects of pH on the formation and properties of HA coatings were systematically examined. Samples exposed to acidic conditions or left without pH adjustment led to the formation of HA, contrasting with the outcomes observed through dissolution methods. Different characterization techniques, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD), were employed to evaluate the quality and crystallinity of the coatings. Among the samples, those exhibiting superior crystallinity and nanostructured features, including bovine HA, were selected for further surface functionalization with the antibiotic enrofloxacin using spin coating. As expected, the antibiotic loading on each material's surface depended on the amount of HA deposited on the substrate. However, the desorption results indicated that, in all cases, desorption persisted beyond 38 h, implying that HA-loaded matrices could be effective systems for controlled and prolonged drug release, which could be useful in dental or orthopedic implants for inhibiting the growth of bacterial biofilms.

Comparison of the physical properties of glass ionomer modified with silver phosphate/hydroxyapatite or titanium dioxide nanoparticles: in vitro study.

Glass ionomer cements (GICs) are the common materials employed in pediatric dentistry because of their specific applications in class I restorations and atraumatic restoration treatments (ART) of deciduous teeth in populations at high risk of caries. Studies show a limited clinical durability of these materials. Attempts have thus been made to incorporate nanoparticles (NPs) into the glass ionomer for improving resistance and make it like the tooth structure. An in vitro experimental study was conducted using the required samples dimensions and prepared based on the test being carried out on the three groups with or without the modification of light-cured glass ionomer. Samples were grouped as follows: control group (G1_C), 2% silver phosphate/hydroxyapatite NPs group (G2_SPH), and 2% titanium dioxide NPs group (G3_TiO2). The physical tests regarding flexural strength (n = 10 per group), solubility (n = 10 per group), and radiopacity (n = 3 per group) were performed. The data were analyzed by Shapiro Wilks test, and one-way analysis of variance (one-way ANOVA), and multiple comparisons by post hoc Tukey's test. The p-value of < 0.05 was considered significant. No statistically significant difference was observed between the control group (G1_C) and (G2_SPH) (p = 0.704) in the flexural strength test, however differences were found between G2_SPH and G3_TiO2 groups, ANOVA (p = 0.006); post hoc Tukey's test (p = 0.014). Pertaining to the solubility, G2_SPH obtained the lowest among the three groups, ANOVA (p = 0.010); post hoc Tukey's test (p = 0.009). The three study groups obtained an adequate radiopacity of >1 mm Al, respectively. The resin-modified glass ionomer cement (RMGIC) was further modified with 2% silver phosphate/hydroxyapatite NPs to improve the physical properties such as enhancing the solubility and sorption without compromising the flexural strength and radiopacity behavior of modified RMGIC. The incorporation of 2% titanium dioxide NPs did not improve the properties studied.

Biological evaluation of critical bone defect regeneration using hydroxyapatite/ alginate composite granules.

PURPOSE: to evaluate biocompatibility and osteogenic potential of hydroxyapatite/alginate composite after its implantation on rat calvarian critical bone defect. METHODS: thirty adults male Wistar rats were randomly distributed into two groups: GHA - critical bone defect filled with hydroxyapatite/alginate composite granules (HA/Alg) and CG - critical bone defect without biomaterial; evaluated at biological points of 15, 45 and 120 days. RESULTS: the histomorphometrically analyses for GHA showed osteoid matrix deposition (OM) among the granules and towards the center of the defect in centripetal direction throughout the study, with evident new bone formation at 120 days, resulting in filling 4/5 of the initial bone defect. For CG, this finding was restricted to the edges of the bone margins and formation of connective tissue on the residual area was found in all biological points. Inflammatory response on GHA was chronic granulomatous type, discrete and regressive for all biological points. Throughout the study, the CG presented mononuclear inflammatory infiltrate diffuse and regressive. Histomorphometry analyses showed that OM percentage was evident for GHA group when compared to CG group in all analyzed periods (p > 0.05). CONCLUSIONS: the biomaterial evaluated at this study showed to be biocompatible, bioactive, osteoconductive and biodegradable synchronously with bone formation.