4-META/MMA-TBB resin containing nano hydroxyapatite induces the healing of periodontal tissue repair in perforations at the pulp chamber floor.

We aimed to evaluate the materials based on 4-methacryloxyethyl trimellitate anhydride/methyl methacrylate tri-n-butylborane (Super-bond [SB]) and nano hydroxyapatite (naHAp) for the repair of perforation at pulp chamber floor (PPF) in vitro and in vivo models. SB and naHAp were mixed in the mass ratio of 10% or 30% to produce naHAp/SB. Human periodontal ligament stem cells (HPDLSCs) were cultured on resin discs of SB or naHAp/SB to analyze the effects of naHAp/SB on cell adhesion, proliferation, and cementoblastic differentiation. A rat PPF model was treated with SB or naHAp/SB to examine the effects of naHAp/SB on the healing of defected cementum and periodontal ligament (PDL) at the site of PPF. HPDLSCs were spindle-shaped and adhered to all resin discs. Changing the resin from SB to naHAp/SB did not significantly alter cell proliferation. Both 10% and 30% naHAp/SB were more effective than SB in promoting cementoblastic differentiation of HPDLSCs. In the rat PPF model, 30% naHAp/SB was more effective than SB in promoting the formation Sharpey's fiber-like structures with expression of the PDL-related marker and cementum-like structures with expression of cementum-related markers. In conclusion, 30% naHAp/SB can be the new restorative material for PPF because it exhibited the abilities of adhering to dentin and healing of defected periodontal tissue.

Effect of air-abrasion pretreatment with three desensitizing agents on efficacy of in-office tooth bleaching.

OBJECTIVE: To evaluate the influence of air-abrasion of enamel with three different desensitizing powders on the whitening effect of a bleaching gel containing 40% H2O2, which was used for in-office tooth bleaching. MATERIALS AND METHODS: Forty human incisors, extracted and prepared, were acquired for this study and subsequently randomized into four groups (n = 10). The control group specimens underwent no pretreatment prior to the bleaching procedure, whereas the remaining three groups underwent air abrasion using distinct desensitizing powders; (a) Sylc, which contains bioglass 45S5; (b) BioMinF, which contains calcium phospho-fluoro-silicate glass; and (c) MI Pearls, which contains nano-hydroxyapatite, 1 h preceding the Opalescence Boost PF 40% bleaching procedure. Color measurements were conducted using a double-beam UV-Vis spectrophotometer at four distinct time points (prior to bleaching, 24 h, 15 days, and 30 days post-bleaching). RESULTS: Tooth color change outcomes revealed that there were no statistically significant results with respect to the interaction of the two criteria (treatments and time) (p = 0.990). Additionally, there were no statistically significant results with respect to the main effects of treatments (p = 0.385), while there were statistically significant effects with respect to the time criterion (p = 0.013). CONCLUSIONS: The use of the tested desensitizing powders prior the bleaching procedure did not affect the tooth color change induced by the tested bleaching agent. CLINICAL SIGNIFICANCE: Tooth color change and whiteness are not affected by air-abrasion desensitizing treatments when applied prior to in-office bleaching procedures.

Deciphering the role of micro/nano-hydroxyapatite in aerobic granular sludge system: Effects on treatment performance and enhancement mechanism.

Hydroxyapatite (HAP), a mineral nucleus identified within aerobic granular sludge (AGS), plays a vital role in enhancing the AGS systems. However, the microscopic mechanism underlying their roles remains largely unexplored. Herein, a systematic investigation was carried out to elucidate the impact and enhanced mechanisms associated with HAP of different sizes, i.e. micro-HAP (mHAP) and nano-HAP (nHAP), on the aerobic granulation, nutrient removal and microbial diversity of AGS. Results showed that the presence of nHAP and mHAP significantly shortened the granulation process to 15 and 20 days, respectively. This might be ascribed to the fact that the large specific surface area of nHAP aggregates was conducive to microbial adhesion, biomass accumulation and sludge granulation. Compared with mHAP, the granules with nHAP showed better settlement performance, mechanical strength and larger diameter. The X-ray diffraction (XRD) and Raman spectrometer analysis confirmed the presence of HAP within the granules, which was found to stimulate the secretion of extracellular polymeric substance, improve the compactness of granule structure and suppress the growth of filamentous bacteria, thereby contributing to a stable AGS system. The presence of HAP, especially nHAP, effectively enriched the functional microorganisms, such as nitrifying and denitrifying bacteria (e.g. Candidatus_Competibacter) and phosphorus accumulating organisms (e.g. Flavobacterium), leading to the improved nutrient removal efficiencies (COD > 96%, TN > 76%, and TP > 74%). Further analysis revealed the up-regulation of functional enzymes (e.g. nitrite oxidoreductase and polyphosphate kinase) involved in nutrient metabolism, underlying the inherent mechanisms for the excellent nutrient removal. This study deepens the understanding of granulation mechanisms from the perspective of mineral cores, and proposes an economically feasible strategy for rapid initiation and stabilization of AGS reactors.

On the osteogenic differentiation of dental pulp stem cells by a fabricated porous nano-hydroxyapatite substrate loaded with sodium fluoride.

In the present study, nano-hydroxyapatite (n-HA) powder was extracted from carp bone waste to fabricate porous n-HA substrates by a molding and sintering process. Subsequently, the substrates were loaded with different amounts of sodium fluoride (NaF) through immersion in NaF suspensions for 10, 7.5, and 5 min. The NaF-loaded n-HA substrates were then examined for their structural and physical properties, chemical bonds, loading and release profile, pH changes, cytotoxicity, and osteogenic effect on dental pulp stem cells (DPSCs) at the level of RNA and protein expression. The results showed that the n-HA substrates were porous (> 40% porosity) and had rough surfaces. The NaF could be successfully loaded on the substrates, which was 6.43, 4.50, and 1.47 mg, respectively for n-HA substrates with immersion times of 10, 7.5, and 5 min in the NaF suspensions. It was observed that the NaF release rate was rather fast during the first 24 h in all groups (39.06%, 36.43%, and 39.57% for 10, 7.5, and 5 min, respectively), and decreased dramatically after that, indicating a slow detachment of NaF. Furthermore, the pH of the medium related to all materials was changed during the first 4 days of immersion (from 7.38 to pH of about 7.85, 7.84, 7.63, and 7.66 for C0, C5, C7.5, and C10, respectively). The pH of media associated with the C7.5, and C10 increased up to 4 days and remained relatively constant until day 14 (pH = 7.6). The results of the cytotoxicity assay rejected any toxicity of the fabricated NaF-loaded n-HA substrates on DPSCs, and the cells could adhere to their surfaces with enlarged morphology. The results showed no effect on the osteogenic differentiation at the protein level. Nevertheless, this effect was observed at the gene level.

Printing tissue-engineered scaffolds made of polycaprolactone and nano-hydroxyapatite with mechanical properties appropriate for trabecular bone substitutes.

BACKGROUND: Bone tissue engineering, based on three-dimensional (3D) printing technology, has emerged as a promising approach to treat bone defects using scaffolds. The objective of this study was to investigate the influence of porosity and internal structure on the mechanical properties of scaffolds. METHODS: We fabricated composite scaffolds (which aimed to replicate trabecular bone) from polycaprolactone (PCL) reinforced with 30% (wt.) nano-hydroxyapatite (nHAp) by extrusion printing. Scaffolds with various porosities were designed and fabricated with and without an interlayer offset, termed as staggered and lattice structure, respectively. Mechanical compressive testing was performed to determine scaffold elastic modulus and yield strength. Linear regression was used to evaluate mechanical properties as a function of scaffold porosity. RESULTS: Different relationships between mechanical properties and porosities were noted for the staggered and lattice structures. For elastic moduli, the two relationships intersected (porosity = 55%) such that the lattice structure exhibited higher moduli with porosity values greater than the intersection point; vice versa for the staggered structure. The lattice structure exhibited higher yield strength at all porosities. Mechanical testing results also indicated elastic moduli and yield strength properties comparable to trabecular bone (elastic moduli: 14-165 MPa; yield strength: 0.9-10 MPa). CONCLUSIONS: Taken together, this study demonstrates that scaffolds printed from PCL/30% (wt.) nHAp with lattice and staggered structure offer promise for treating trabecular bone defects. This study identified the effect of porosity and internal structure on scaffold mechanical properties and provided suggestions for developing scaffolds with mechanical properties for substituting trabecular bone.

Application of nano-hydroxyapatite matrix graft in inter-vertebral fusion therapy: a meta-analysis.

OBJECTIVE: Nano-hydroxyapatite and its composites(nHA) have been widely used as grafts in inter-vertebral fusion. However, the safety and efficacy of the graft in inter-vertebral fusion is controversial. This meta-analysis aimed at evaluating the safety and efficacy of nHA and non-hydroxyapatite grafts (noHA) (autologous bone, etc.) in inter-body fusion. MATERIALS AND METHODS: A comprehensive search was performed in electronic database as follows: PubMed, EMBASE, the Cochrane Library, Web of Science, and China National Knowledge Internet (CNKI) from inception until October 2022. Clinical studies on the effect of nHA and noHA in spinal fusion were collected. Analysis of outcome indicators using RevMan 5.4 statistical software. RESULTS: The meta-analysis showed that the operation time of patients who underwent inter-body fusion with nHA grafts was less than that of patients who underwent noHA (p < 0.05). Compared with the noHA group, the nHA group can achieve similar clinical effects in the fusion rate(OR = 1.29,95%CI: 0.88 to 1.88,p = 0.19),Subsidence rate(OR = 1.2,95%CI:0.44 to 3.28,p = 0.72), inter-vertebral space height(SMD = 0.04,95%CI:-0.08 to 0.15,p = 0.54),Cobb angle(SMD = 0.21,95%CI: 0.18 to 0.6,p = 0.21),Blood loss(SMD = -36.58,95%CI: -81.45 to 8.29,p = 0.11),operative time in 12 months(SMD = -5.82,95%CI: -9.98 to -1.67,p = 0.006) and in the final follow-up(SMD = -0.38,95%CI: -0.51 to -0.26,p < 0.00001),ODI(SMD = 0.68,95%CI: -0.84 to 2.19,p = 0.38), VAS(SMD = 0.17,95%CI: -0.13 to 0.48,p = 0.27) and adverse events(OR = 0.98,95%CI: 0.66 to 1.45,p = 0.92), and the differences are not statistically significant. CONCLUSION: This meta-analysis suggests that nHA matrix grafts are similar to noHA grafts in the safety and efficacy of spinal reconstruction, and are an ideal material for inter-vertebral bone grafting.

Characterization of nano-hydroxyapatite incorporated carboxymethyl chitosan composite on human dental pulp stem cells.

AIM: To compare the odontogenic differentiation potential of a composite scaffold (CSHA) comprising of nano-hydroxyapatite (nHAp) and carboxymethyl chitosan (CMC) with Biodentine on human dental pulp stem cells (hDPSCs). METHODOLOGY: A CSHA scaffold was prepared through an ultrasonication route by adding nHAp and CMC (1:5 w/w) in water medium followed by freeze-drying. Physicochemical characterization was achieved using scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy. In-vitro bioactivity and pH assessments were done by soaking in simulated body fluid (SBF) for 28 days. The angiogenic and odontogenic differentiation abilities were assessed by expression of vascular endothelial growth factor (VEGF) and Dentine sialophosphoprotein (DSPP) markers on cultured hDPSCs by flow cytometry and RT-qPCR at 7, 14 and 21 days. Cell viability/proliferation and biomineralization abilities of CSHA were compared with Biodentine by MTT assay, alkaline phosphatase (ALP) activity, Alizarin Red Staining (ARS) and osteopontin (OPN) expression on hDPSCs following 7 and 14 days. Data were statistically analysed with Kruskal Wallis and Friedman tests as well as one way anova followed by appropriate post hoc tests (p < .05). RESULTS: Characterization experiments revealed a porous microstructure of CSHA with pore diameter ranging between 60 and 200 µm and 1.67 Ca/P molar ratio along with the characteristic functional groups of both HAp and CMC. CSHA displayed bioactivity in SBF by forming apatite-like crystals and maintained a consistent pH value of 7.70 during 28 days' in vitro studies. CSHA significantly upregulated VEGF and DSPP levels on hDPSCs on day 21 compared with day 7 (p < .05). Further, CSHA supported cell viability/proliferation over 14 days like Biodentine with no statistical differences (p > .05). However, CSHA exhibited increased ALP and ARS activity with an intense OPN staining compared with Biodentine after 14 days (p < .05). CONCLUSION: The results highlighted the odontogenic differentiation and biomineralization abilities of CSHA on hDPSCs with significant VEGF and DSPP gene upregulations. Further, CSHA exhibited enhanced mineralization activity than Biodentine, as evidenced by increased ALP, ARS and OPN activity on day 14. The nHAp-CMC scaffold has the potential to act as an effective pulp capping agent; however, this needs to be further validated through in-vivo animal studies.

In vitro release of silver ions and expression of osteogenic genes by MC3T3-E1 cell line cultured on nano-hydroxyapatite and silver/strontium-coated titanium plates.

Attempts are ongoing to improve the surface properties of dental implants by application of different coatings, aiming to enhance osseointegration, and decrease the adverse effects of titanium and its alloys used in dental implants. Coating of implant surface with hydroxyapatite (HA) is one suggested strategy for this purpose due to its high biocompatibility and similar structure to the adjacent bone. This study aimed to quantify the release of silver ions and expression of osteogenic genes by MC3T3-E1 cells cultured on nano-HA and silver/strontium (Ag/Sr)-coated titanium plates via the electrochemical deposition method. Plates measuring 10 × 10 × 0.9 mm were fabricated from Ti-6Al-4 V alloy, and polished with silicon carbide abrasive papers before electrochemical deposition to create a smooth, mirror-like surface. After applying homogenous nano-HA coatings with/without silver/strontium on the surface of the plates, the composition of coatings was confirmed by energy-dispersive X-ray spectroscopy (EDS), and their morphological properties were analyzed by scanning electron microscopy (SEM). The coated specimens were then immersed in simulated body fluid (SBF), and the concentration of released sliver ions was quantified by spectroscopy at 7-14 days. The MC3T3-E1 osteoblastic cell line was cultured in osteogenic medium for 7-14 days, and after RNA extraction and cDNA synthesis, the expression of runt-related transcription factor 2 (RUNX2), osteocalcin (OCN), and osteopontin (OPN); osteogenic genes was quantified by polymerase chain reaction (PCR) using SYBR Green Master Mix kit. The expression of genes and the released amount of silver ions were compared between the two groups using the Mann-Whitney U test. The two groups were not significantly different regarding silver ion release at 14 days (P > 0.05). However, silver ion release was significantly higher from nano-HA coatings with silver/strontium at 7 days (P = 0.03). The difference in expression of RUNX2 (P = 0.04), OPN (P = 0.04), and OCN (P = 0.03) genes was also significant between nano-HA coating groups with and without silver/strontium at 7 days, and the expressions were higher in nano-HA with silver/strontium group, but this difference was not significant at 14 days. Addition of silver and strontium to specimens coated with nano-HA increased the release of silver ions within the non-toxic range, and enhanced the expression of osteogenic genes particularly after 7 days.

Nano-Hydroxyapatite Composite Scaffolds Loaded with Bioactive Factors and Drugs for Bone Tissue Engineering.

Nano-hydroxyapatite (n-HAp) is similar to human bone mineral in structure and biochemistry and is, therefore, widely used as bone biomaterial and a drug carrier. Further, n-HAp composite scaffolds have a great potential role in bone regeneration. Loading bioactive factors and drugs onto n-HAp composites has emerged as a promising strategy for bone defect repair in bone tissue engineering. With local delivery of bioactive agents and drugs, biological materials may be provided with the biological activity they lack to improve bone regeneration. This review summarizes classification of n-HAp composites, application of n-HAp composite scaffolds loaded with bioactive factors and drugs in bone tissue engineering and the drug loading methods of n-HAp composite scaffolds, and the research direction of n-HAp composite scaffolds in the future is prospected.

Self-Prepared Hyaluronic Acid/Alkaline Gelatin Composite with Nano-Hydroxyapatite and Bone Morphogenetic Protein for Cranial Bone Formation.

New bone-forming substitute materials are highly useful in dental implantology. The purpose of this study was to prepare cross-linked hyaluronic acid (cHLA)/cross-linked alkaline gelatin (cAG)/nano-hydroxyapatite (nHAp)/bone morphogenic protein (BMP) constructs; and evaluate their bone-forming capabilities in rat cranial bone defects. The cHLA and cAG liquids processed with an epoxy cross-linker were blended with a 3:1 volume ratio, followed by freeze-drying. The dry composites were further infiltrated with water containing nHAp only (BMP (−)) or with water containing nHAp and BMP (BMP (+)). Prepared wet constructs (BMP (−) and BMP (+)) were implanted in rat cranial bone defects, while defects only were also made, and animals were fed for 8 weeks, followed by subsequent soft X-ray measurements and histological observations. The X-ray results showed that BMP (+) constructs disappeared, though caused inward extension of peripherical bone from defect edges with an increase in length of approximately 24%, larger than those of BMP (−) constructs and defect only with approximately 17% and 8% increments, respectively (p < 0.05). Histological observations of BMP (+) construct samples clearly indicated active bone extension consisting of an array of island-like bones. It was concluded that cHLA/cAG/nHAp/BMP could be used as novel bone-substitute materials.

Surface topography and spectrophotometric assessment of white spot lesions restored with nano-hydroxyapatite-containing universal adhesive resin: an in-vitro study.

BACKGROUND: White spot lesion (WSL) is a main shortcoming accompanied by orthodontic treatment. It impairs the esthetic, surface hardness, and surface texture of enamel. So, this study was conducted to analyze the surface characteristics and color change of white spot lesions treated with nano-hydroxyapatite (nHA)-enriched universal adhesive resin. MATERIALS AND METHODS: Eighty sound human permanent molars crowns were sectioned into two halves, producing 160 specimens. 16 specimens were left untreated, and 144 specimens were artificially-demineralized to generate WSLs. The specimens were classified according to the treatment approach applied as follows: I; Sound enamel, Group II; artificially-created WSLs, Group III; ICON resin-restored WSLs, Group IV; Universal adhesive resin-restored WSLs, Group V; 0.5 wt% nHA-containing universal adhesive resin-restored WSLs, Group VI; 1 wt% nHA-containing universal adhesive resin- restored WSLs, and Group VII; 3 wt% nHA-containing universal adhesive resin-restored WSLs, Group VIII; 5 wt% nHA-containing universal adhesive resin-restored WSLs, Group IX; 7 wt% nHA-containing universal adhesive resin-restored WSLs, and Group X; 10 wt% nHA-containing universal adhesive resin-restored WSLs. Some surface characteristics and color changes were assessed. Data was collected and analyzed statistically using ANOVA and the Tukey test at p < 0.05. RESULTS: Surface microhardness of WSLs was significantly improved with all investigated ratios of nHA-containing universal adhesive (p < 0.0001), with the highest mean belonging to 10 wt% nHA-containing universal adhesive resin treated WSLs. All ratios of nHA-containing universal adhesive resin significantly reduced the surface roughness of WSLs (p < 0.0001). The investigated ratios of 1, 3, 5, 7, and 10 wt% nHA-containing universal adhesive resin treatment approach could mask the WSLs significantly (p < 0.0001). CONCLUSIONS: Nano-hydroxyapatite-containing universal adhesive is a promising contemporary approach for the management of WSLs, coupled both the remineralizing concept and the minimally invasive resin infiltration.

Evaluation of osteogenic potential of demineralized dentin matrix hydrogel for bone formation.

OBJECTIVES: Dentin, the bulk material of the tooth, resemble the bone's chemical composition and is considered a valuable bone substitute. In the current study, we assessed the cytotoxicity and osteogenic potential of demineralized dentin matrix (DDM) in comparison to HA nanoparticles (n-HA) on bone marrow mesenchymal stem cells (BMMSCs) using a hydrogel formulation. MATERIALS AND METHODS: Human extracted teeth were minced into particles and treated via chemical demineralization using ethylene diamine tetra-acetic acid solution (EDTA) to produce DDM particles. DDM and n-HA particles were added to the sodium alginate then, the combination was dripped into a 5% (w/v) calcium chloride solution to obtain DDM hydrogel (DDMH) or nano-hydroxyapatite hydrogel (NHH). The particles were evaluated by dynamic light scattering (DLS) and the hydrogels were evaluated via scanning electron microscope (SEM). BMMSCs were treated with different hydrogel concentrations (25%, 50%, 75% and neat/100%) and cell viability was evaluated using MTT assay after 72 h of culture. Collagen-I (COL-I) gene expression was studied with real-time quantitative polymerase chain reaction (RT-qPCR) after 3 weeks of culture and alkaline phosphatase (ALP) activity was assessed using enzyme-linked immune sorbent assay (ELISA) over 7th, 10th, 14th and 21st days of culture. BMMSCs seeded in a complete culture medium were used as controls. One-way ANOVA was utilized to measure the significant differences in the tested groups. RESULTS: DLS measurements revealed that DDM and n-HA particles had negative values of zeta potential. SEM micrographs showed a porous microstructure of the tested hydrogels. The viability results revealed that 100% concentrations of either DDMH or NHH were cytotoxic to BMMSCs after 72 h of culture. However, the cytotoxicity of 25% and 50% concentrations of DDMH were not statistically significant compared to the control group. RT-qPCR showed that COL-I gene expression was significantly upregulated in BMMSCs cultured with 50% DDMH compared to all other treated or control groups (P < 0.01). ELISA analysis revealed that ALP level was significantly increased in the groups treated with 50% DDMH compared to 50% NHH after 21 days in culture (P < 0.001). CONCLUSION: The injectable hydrogel containing demineralized dentin matrix was successfully formulated. DDMH has a porous structure and has been shown to provide a supporting matrix for the viability and differentiation of BMMSCs. A 50% concentration of DDMH was revealed to be not cytotoxic to BMMSCs and may have a great potential to promote bone formation ability.

Acceptance and awareness of southeastern and western private practice pediatric dentists of fluoride-free toothpastes: a survey study.

The American Academy of Pediatric Dentistry (AAPD) affirms that the use of fluoride, as an adjunct in the prevention of caries, is safe and effective. The AAPD encourages dentists, other healthcare providers, and parents to optimize fluoride exposures to reduce the risk of caries and to enhance the remineralization of affected teeth. However, there is resistance amongst patients towards fluoride overexposure and despite there being research on other effective remineralizing agents, most pediatric dentists primarily cater their practice to fluoride-based products. The objective of the study is to survey pediatric dentists' acceptance and awareness of fluoride-free remineralizing agents. A listserv of the southeastern and western private practice pediatric dentists was obtained from the AAPD consisting of 6490 email addresses. A questionnaire consisting of 15 questions was sent to each address using Qualtrics. Different trends in fluoride-free acceptance and awareness were seen based on region of practice, region of training and age of practitioner. Region of practice, residency training and age can be contributing factors toward fluoride-free remineralizing agent opinion. The data gathered trends towards western-trained pediatric dentists are more likely to recommend a fluoride-free toothpaste than a southeastern-trained dentist.

3D printed polylactic acid/gelatin-nano-hydroxyapatite/platelet-rich plasma scaffold for critical-sized skull defect regeneration.

BACKGROUND: Three-dimensional (3D) printing is a capable approach for the fabrication of bone tissue scaffolds. Nevertheless, a purely made scaffold such as polylactic acid (PLA) may suffer from shortcomings and be restricted due to its biological behavior. Gelatin, hydroxyapatite and platelet-rich plasma (PRP) have been revealed to be of potential to enhance the osteogenic effect. In this study, it was tried to improve the properties of 3D-printed PLA scaffolds by infilling them with gelatin-nano-hydroxyapatite (PLA/G-nHA) and subsequent coating with PRP. For comparison, bare PLA and PLA/G-nHA scaffolds were also fabricated. The printing accuracy, the scaffold structural characterizations, mechanical properties, degradability behavior, cell adhesion, mineralization, systemic effect of the scaffolds on the liver enzymes, osteocalcin level in blood serum and in vivo bone regeneration capability in rat critical-sized calvaria defect were evaluated. RESULTS: High printing accuracy (printing error of < 11%) was obtained for all measured parameters including strut thickness, pore width, scaffold density and porosity%. The highest mean ultimate compression strength (UCS) was associated with PLA/G-nHA/PRP scaffolds, which was 10.95 MPa. A slow degradation rate was observed for all scaffolds. The PLA/G-nHA/PRP had slightly higher degradation rate, possibly due to PRP release, with burst release occurred at week 4. The MTT results showed that PLA/G-nHA/PRP provided the highest cell proliferation at all time points, and the serum biochemistry (ALT and AST level) results indicated no abnormal/toxic influence caused by scaffold biomaterials. Superior cell adhesion and mineralization were obtained for PLA/G-nHA/PRP. Furthermore, all the developed scaffolds showed bone repair capability. The PLA/G-nHA/PRP scaffolds could better support bone regeneration than bare PLA and PLA/G-nHA scaffolds. CONCLUSION: The PLA/G-nHA/PRP scaffolds can be considered as potential for hard tissue repair.

Nano-hydroxyapatite modified biochar: Insights into the dynamic adsorption and performance of lead (II) removal from aqueous solution.

Adsorption of lead as Pb(II) using biochar is an environmentally sustainable approach to remediate this kind of pollution affecting wastewater. In this study, rice straw biochar (BC) was modified by combination with nano-hydroxy-apatite (HAP), resulting in a material designated as BC@nHAP, with enhanced adsorption performance. Based on Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses, it was evidenced that, after modification, HAP greatly enhanced surface functional groups (i.e., -COOH and/or -OH) of raw biochar's surface. Batch tests showed that the maximum sorption capacity of BC (63.03 mg g-1) was improved due to the modification, reaching 335.88 mg g-1 in BC@nHAP. Pseudo-second order (PSO) kinetics fitted well the adsorption data (R2 = 0.99), as well as the Langmuir isotherm model (showing an adsorption value of 335.88 mg g-1 for qe). The results of thermodynamic calculations showed that the adsorption was primarily governed by chemisorption process. FTIR spectroscopy and XPS spectrum after adsorption further confirmed that the adsorption mechanisms were ion exchange with Pb2+ and surface complexation by -OH and -COOH. In addition, BC@nHAP revealed a brilliant regeneration capability. The maximum adsorption capacity by BC@nHAP was higher than that of raw biochar or other previously reported adsorbents. Therefore, BC@nHAP could be seen as a new sorbent material with high potential for real-scale heavy metal removal from wastewater, and specifically as a capable candidate new sorbent for Pb(II) removal from wastewater, which has clear implications as regard preservation of environmental quality and public health.

Synthesis of nano hydroxyapatite from Hypopthalmichthys molitrix (silver carp) bone waste by two different methods: a comparative biophysical and in vitro evaluation on osteoblast MG63 cell lines.

More than a thousand tonnes of fish bone wastes can be transformed into biomedical products annually. Alkaline hydrolysis and thermal calcification were used to create nanosized hydroxyapatite (HAp) crystals from Silver carp bone wastes. Biophysical tests were used to determine the nano size and chemical composition of synthesised hydroxyapatite. Alkaline hydrolysis hydroxyapatite (AH-HAp) was 58.3 nm, while Thermal calcination hydroxyapatite (TC-HAp) was 64.3 nm in size, confirmed by Atomic Force Microscopy. Energy Dispersive X-ray Analysis studies showed Ca/P (Calcium phosphate) ratio of AH-HAp to be 1.65, whereas TC-HAp as 1.45, confirming AH-HAp to be organically rich along with a similar Ca/P ratio as natural HAp. Fourier Transform Infrared Spectroscopy spectra indicated HAp formation from both procedures, however AH-HAp had superior crystallinity than TC-HAp confirmed from X-Ray Diffraction spectra. MG63 osteoblast cell lines showed 91% cell viability in cytotoxicity studies and 70.1% proliferation efficiency in Alkaline Phosphatase assay, which was higher than TC-HAp. The present study shows that HAp produced via alkaline hydrolysis has better biocompatibility which enhances its applicability as a biomaterial, than HAp synthesized through thermal calcination, which tends to incinerate organic moieties.

Eggshell derived nano-hydroxyapatite incorporated carboxymethyl chitosan scaffold for dentine regeneration: A laboratory investigation.

AIM: To assess odontogenic differentiation abilities of porous biomineralizable composite scaffolds comprising eggshell derived nano-hydroxyapatite (HAnp) and carboxymethyl chitosan (CMC) on cultured human dental pulp stem cells (hDPSCs). METHODOLOGY: Nano-hydroxyapatite was derived from eggshells using a simple combustion method and CMC was prepared from chitosan through a chemical route. Several compositions of HAnp-CMC (0:5, 5:0, 1:5, 2:5, 3:5, 4:5 and 1:1 w/w%) scaffolds were prepared by magnetic stirring and freeze-drying methods. HAnp-CMC scaffolds were characterized using high-resolution scanning electron microscopy combined with energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction methods. In vitro bioactivity was determined following the interaction in simulated body fluid for 21 days. The optimized composite was then loaded onto hDPSCs to assess cell viability/proliferation, dentine sialophosphoprotein (DSPP) and vascular endothelial growth factor (VEGF) expressions using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, real-time quantitative polymerase chain reaction and flow cytometry methods, respectively, following 7, 14 and 21 days. For intergroup and intragroup comparisons, Kruskal-Wallis and Friedman tests were employed, respectively, followed by appropriate post hoc test (Dunn). Significant levels were set at *p < .05 and *p < .01. RESULTS: Synthesized hydroxyapatite (HAp) comprised crystals ranging from 20 to 50 nm (HAnp) with spherulite morphology and calcium/phosphorus (Ca/P) molar ratio of 1.67. The ultrastructure of all the scaffolds revealed a highly interconnected porous microstructure, whilst the chemical characterization displayed specific functional groups of both HAnp and CMC. In vitro bioactivity assessment confirmed the biomineralization potential of all scaffolds with an apatite-like crystal formation on the surface. The 1:5 HAnp-CMC revealed a favourable pore size (60-180 µm) that was suitable for cell seeding and was chosen for further experiments. Cell viability/proliferation rates of hDPSCs loaded 1:5 HAnp-CMC at 21st day was significantly greater than that at 7th day (p < .05). The mean relative quantification of DSPP expression by the scaffold was significantly higher (p < .05) on day 21 (3.16) than on day 7 (1.67). Mean fluorescence intensity of the VEGF expression at day 21 (32.5) was also significantly higher (p < .01) than at day 7 (12.54). CONCLUSION: hDPSCs on 1:5 HAnp-CMC scaffolds displayed increased cell viability/proliferation and enhanced DSPP as well as VEGF expressions. The 1:5 HAnp-CMC composite has the potential to serve as a promising scaffold for dentine regeneration.

Nano-hydroxyapatite-induced remineralization of artificial white spot lesions after bleaching treatment with 10% carbamide peroxide.

OBJECTIVE: To assessed in vitro the effect of nanohydroxyapatite (n-HA) to improve the aesthetic appearance and microhardness of white spot lesions (WSL) when associated with a low-concentration bleaching agent (carbamide peroxide-CP10%). MATERIAL AND METHODS: Enamel/dentin specimens (n = 60) of 5 × 5 × 2.2 mm were prepared, of these, 48 were submitted to pH-cycling to create artificial WSL. Subsequently, these were allocated into five groups (n = 12): n-HA; n-HA + CP10%; CP10%; WSL control (WSLC ); sound control (Sound). The color was assessed at baseline, pre-treatment, and post-treatment using a spectrophotometer, and the color (ΔE/ΔE00 ) and whiteness index (ΔWID) alterations were determined. The enamel cross-sectional microhardness (CSMH) was evaluated (post-treatment) with a Knoop indenter, 25gf/5 s, 20-200 µm. The data was analyzed through generalized linear models (α = 5%). RESULTS: ΔE and ΔE00 were significantly higher for the bleached groups (n-HA + CP10% and CP10%), and the n-HA was higher than the WSLC group (p < 0.05). ΔWID was significantly higher for the bleached groups (p < 0.05). The CSMH values were significantly higher in the sound group than in the n-HA, CP10%, and WSLC groups (p < 0.05). The WSLC had lower microhardness than the n-HA + CP10% and sound groups (p < 0.05). CONCLUSION: n-HA is suitable to remineralize and recover the color of the WSL. However, its association with CP10% maintains the esthetical outcome while increasing its in-depth remineralizing effect. CLINICAL SIGNIFICANCE: Considering the aesthetic and functional repercussions of the WSL persistence, treatments that tend to improve its physical appearance and reinforce its weakened substructure in a non-invasive way are ideal. For this associating low-concentration, bleaching agents to the remineralizing treatments is promising to treat this type of lesions.

The osteogenic differentiation of human dental pulp stem cells in alginate-gelatin/Nano-hydroxyapatite microcapsules.

BACKGROUND: Microcapsule is considered as a promising 3D microenvironment for Bone Tissue Engineering (BTE) applications. Microencapsulation of cells in an appropriate scaffold not only protected the cells against excess stress but also promoted cell proliferation and differentiation. Through the current study, we aimed to microcapsulate the human Dental Pulp Stem Cells (hDPSCs) and evaluated the proliferation and osteogenic differentiation of those cells by using MTT assay, qRT-PCR, Alkaline phosphatase, and Alizarine Red S. RESULTS: The SEM results revealed that Alg/Gel microcapsules containing nHA showed a rough and more compact surface morphology in comparison with the Alg/Gel microcapsules. Moreover, the microencapsulation by Alg/Gel/nHA could improve cell proliferation and induce osteogenic differentiation. The cells cultured in the Alg/Gel and Alg/Gel/nHA microcapsules showed 1.4-fold and 1.7-fold activity of BMP-2 gene expression more in comparison with the control group after 21 days. The mentioned amounts for the BMP-2 gene were 2.5-fold and 4-fold more expression for the Alg/Gel and Alg/Gel/nHA microcapsules after 28 days. The nHA, addition to hDPSCs-laden Alg/Gel microcapsule, could up-regulate the bone-related gene expressions of osteocalcin, osteonectin, and RUNX-2 during the 21 and 28 days through the culturing period, too. Calcium deposition and ALP activities of the cells were observed in accordance with the proliferation results as well as the gene expression analysis. CONCLUSION: The present study demonstrated that microencapsulation of the hDPSCs inside the Alg/Gel/nHA hydrogel could be a potential approach for regenerative dentistry in the near future.

Fabrication and Characterization of Nanocomposite Hydrogel Based on Alginate/Nano-Hydroxyapatite Loaded with Linum usitatissimum Extract as a Bone Tissue Engineering Scaffold.

In the current paper, we fabricated, characterized, and applied nanocomposite hydrogel based on alginate (Alg) and nano-hydroxyapatite (nHA) loaded with phenolic purified extracts from the aerial part of Linum usitatissimum (LOH) as the bone tissue engineering scaffold. nHA was synthesized based on the wet chemical technique/precipitation reaction and incorporated into Alg hydrogel as the filler via physical cross-linking. The characterizations (SEM, DLS, and Zeta potential) revealed that the synthesized nHA possess a plate-like shape with nanometric dimensions. The fabricated nanocomposite has a porous architecture with interconnected pores. The average pore size was in the range of 100-200 µm and the porosity range of 80-90%. The LOH release measurement showed that about 90% of the loaded drug was released within 12 h followed by a sustained release over 48 h. The in vitro assessments showed that the nanocomposite possesses significant antioxidant activity promoting bone regeneration. The hemolysis induction measurement showed that the nanocomposites were hemocompatible with negligible hemolysis induction. The cell viability/proliferation confirmed the biocompatibility of the nanocomposites, which induced proliferative effects in a dose-dependent manner. This study revealed the fabricated nanocomposites are bioactive and osteoactive applicable for bone tissue engineering applications.