Octacalcium phosphate (OCP), a precursor to hydroxyapatite (HA), has recently garnered significant interest from biomaterial researchers both domestically and internationally because OCP has been confirmed to possess the capacity to activate bone-related cells, such as osteoblasts and osteoclasts, and to exhibit high osteogenic potential and bioresorbability if implanted in bone defects. Since OCP contains a large amount of water molecules in its structure, it cannot be sintered as a single crystal phase. Therefore, efforts have been paid to develop molding OCP through combining polymer materials, such as collagen (Col). OCP/Col has been approved in Japan for clinical application as a bone substitute material for combination uses with dental implants in the oral and maxillofacial surgery fields. The aim of this review is to summarize the process leading to the OCP/Col fabrication, as well as the clinical application of OCP/Col, focusing on these materials from chemical, physical, and biological perspectives as biomaterials.

Synergistic role of chitosan and carboxymethyl chitosan in regulating phase maturation and crystallinity of biomimetic calcium phosphate: From precursors to apatite.

Osteosarcoma is a rare cancer affecting disease for children and young adults; complete healing from this condition is quite difficult. Recently, new regeneration materials have been preferred, including natural compound companied implants for affected bone repair, and it is effectively used to treat osteosarcoma disease. Hence, octa calcium phosphate (OCP) reinforced with poly (vinyl alcohol) (PVA) and oleic acid (OA) with naringenin (NRG) composite was prepared and studied to cure the sarcoma affected bone. The physicochemical nature of the prepared OCP, PVA/OA/OCP, and PVA/OA/OCP/NRG composite were characterized by Fourier transforms infrared spectroscopy, scanning electron microscopy, and x-ray diffraction techniques. Thein vitrorelease of the NRG from the PVA/OA/OCP/NRG composite was evaluated by UV-visible spectroscopy and the NRG release rate was observed at 98.0% over 24 h. Biocompatibility and cell viability of the prepared OCP, PVA/OA/OCP, and PVA/OA/OCP/NRG composite are investigated in adipose-derived stem cells on different days. Interestingly, the PVA/OCP/OA/NRG composite shows an increase of 74.0%-92.0% in cell survival, indicating that the composite is biocompatible. Similarly, the ability of NRG in the composite is to suppress cancer cells and it was determined in lung cancer (A549) cells. NRG-loaded PVA/OCP/OA/NRG shows good inhibition ability, nearly 43% at 72 h. From the results, the prepared composite materials can inhibit cancer cells and be viable in stem cell growth. Since the materials will serve as potential regenerative materials for sarcoma-affected bone recovery.

Octacalcium phosphate (OCP) is a bone grafting material known for its biocompatibility, osteoconductive, and osteogenic properties. Current treatments for extensive jaw defects often involve vascularized bone grafts or titanium mesh-based osteogenesis, which have limitations such as graft resorption, infections, and reoperation needs. In this study, a new bone regeneration therapy was explored, in which OCP combined with collagen (Col), treated with teriparatide (TPTD), was encased in a polylactic acid (PLA) cage to enhance structural stability and promote controlled bone formation. The therapeutic effects of this approach were evaluated using a rat model for calvarial regeneration, employing immunohistochemical staining. TPTD-treated OCP/Col composites were encased in cylindrical PLA cages, which were created using a 3D printer, and implanted into rat skulls. Three cage designs were tested: no holes, one large hole, and several small holes. Following implantation, the specimens underwent microcomputed tomography (micro-CT), histological, and immunohistochemical analyses to assess bone regeneration. In the micro-CT analysis, radiopacity at the OCP/Col graft site was higher in the "no hole" cage group than in the other groups from 4 to 12 weeks after implantation, particularly in the marginal area and region adjacent to the bone. Histological analysis revealed that, in all groups, new bone formation was observed along the surface of the skull 12 weeks postimplantation. In the "no hole" cage group, bone formation extended to the upper middle section, and bone matrix was present in areas where mature bone formation was lacking. In the other two groups, fibrous tissue filled the holes in the PLA cage, and no bone formation was observed directly beneath the holes. Immunohistochemical analysis revealed the expression of osteopontin, osteocalcin, runt-related transcription factor 2, vascular endothelial growth factor, and collagen I in all groups. The "no hole" cage group exhibited uniform and successful bone formation, with these cell markers consistently observed throughout all regions. These results suggest that using PLA cages to cover TPTD-treated OCP/Col discs effectively promotes bone regeneration. This approach provides a promising alternative to conventional bone grafting techniques and may help overcome the limitations associated with free or autologous bone grafts in oral and maxillofacial reconstruction.

Bone regeneration, tendon fiber formation, and angiogenesis are enhanced by the multifaceted effects of biodegradable octacalcium phosphate and gelatin scaffold materials

Actuality. Effective oral hygiene products with an anti-plaque effect can significantly reduce the risk of developing diseases. New active ingredients of oral hygiene products, such as octacalcium phosphate, nanohydroxyapatite, aminophthroid, as well as various plant extracts and probiotics, are becoming increasingly popular due to their unique properties that help not only in the fight against plaque, but also in maintaining the health of hard and soft tissues of the mouth. Material and methods. To study the preventive effect of "PRESIDENT® Profi Biomineral" toothpaste, a clinical trial was conducted with the participation of 60 people (34 women, 26 men). The study participants used the preventive toothpaste "PRESIDENT® Profi Biomineral" every day, morning and evening, for 28 days. An objective assessment of the condition of the hard tissues of the mouth was carried out every week in order to determine the anti-caries, remineralizing and desensitizing effects, as well as an assessment of the buffer capacity of saliva. Results. Based on the results of a study of the preventive effect of oral hygiene products based on octacalcium phosphate in the examined patients who used PRESIDENT® Profi Biomineral toothpaste for individual oral hygiene, it was determined that the anti-caries effectiveness increased from 2.03 ± 0.90% to 16.24 ± 4.34% in one month of using PRESIDENT® Profi Biomineral paste. The remineralizing efficacy in one month of using PRESIDENT® Profi Biomineral toothpaste was 24.76 ± 3.92%. The desensitive efficiency increased from 7.11 ± 1.23% to 19.72 ± 5.24% and increased by 12.61%. Conclusion. It was revealed that the toothpaste "PRESIDENT® Profi Biomineral" based on octacalcium phosphate, when used in individual hygiene measures, has a significant preventive effect, which was established as a result of its clinical testing.

The clinical success of calcium phosphate bone grafts (CPs) largely depends on the body’s immune response. However, traditional biocompatibility tests use healthy organisms and cannot predict effectiveness in patients with common chronic inflammatory diseases. This study examines how inflammation modulates the immune response, in vitro and in vivo, to low-temperature biomimetic CPs: dicalcium phosphate dihydrate (DCPD), octacalcium phosphate (OCP), and hydroxyapatite (HAp). In vitro studies involved human monocytes, macrophages, lymphocytes, and mesenchymal stromal cells (MSCs), with or without pro-inflammatory activation. In vivo biocompatibility was assessed via subcutaneous implantation in rats, with or without Complete Freund’s Adjuvant (CFA)-induced inflammation. Under normal conditions, all CP caused minimal immune reactivity. Inflammation-activated macrophages, however, triggered an acute reaction with significantly increased TNF-α and IL-1β secretion. Healthy and inflamed animals showed sharp contrasts. Although all materials exhibited thickened fibrous capsules during inflammation, biocompatibility varied markedly: DCPD performed best by promoting angiogenesis with minimal inflammation; HAp provoked the most severes response, including tissue necrosis and signs of rejection; OCP showed intermediate effects, with angiogenesis but notable fibrosis. Inflammatory processes critically influence CP biocompatibility; materials biocompatible in healthy organisms can induce fibrosis or rejection under inflammation. Disease-relevant, immune-challenged models are essential to predict clinical efficacy and safety.

This study reports the successful synthesis of octacalcium phosphate (OCP) with incorporated 1,4,5,8-naphthalenetetracarboxylate ions. This material achieves a new record for the maximum molecular weight of carboxylic acids that can be incorporated into OCP. Furthermore, we identified a new tetracarboxylic acid that can be incorporated into OCP.

The hierarchical architecture of bone, characterized at the nanoscale, is defined by mineralized collagen fibrils with a disordered, hydrated, carboxylate-rich mineral surface, presenting a complexity often absent in conventional hydroxyapatite (HA) models. Here, we report the design of biomimetic octacalcium phosphate (OCP)-collagen films that reproduce both the crystalline mineral core and the citrate-rich disordered surface of native bone. Phase-pure OCP and citrate-incorporated OCP (OCP-CIT) were synthesized via pH-regulated hydrolysis of α-tricalcium phosphate (α-TCP) under physiological conditions, with citrate inducing structural heterogeneity analogous to natural bone mineral. Electrophoretic deposition facilitated the integration of these minerals into collagen films, aided by hyaluronic acid (HyAc), which stabilized colloidal suspensions by adjusting the zeta potential from -5 to -25 mV and dialysis against DI water by lowering conductivity from ∼30 to 0.01 mS/cm. The resulting films exhibited a collagen-mineral composite composed predominantly of apatitic orthophosphates (74% by ³1P nuclear magnetic resonance (NMR) spectroscopy), with citrate-directed mineral nucleation and HyAc-promoted collagen mineralization. Solid-state NMR rotational-echo double resonance (REDOR) experiments highlighted the essential function of HyAc in establishing proximity between mineral and collagen, absent in citrate-only systems, thereby emulating bone's interfacial organization. The work establishes a scalable film-based strategy for creating physiologically relevant bone analogues, with implications for advancing bone graft materials and disease models.

Enhanced cortical bone formation ability and antibacterial properties of silica-substituted octacalcium phosphate blocks through silver loading

Aim: To reveal the applicability of lectin histochemistry methods for the evaluation of bone tissue injury recovery. Materials and Methods: The research was accomplished on 35 mature rabbits aged 6-7 months weighting 2.5-3 kg subdivided into three groups. Control group included 10 rabbits with post traumatic mandibular bone injury site healed under the blood cloth. First experimental group consisted of animals with damaged bone recovery supplemented with an osteotropic material based on native octacalcium phosphate (OCP-N). Second experimental group consisted of rabbits with bone defect filled with natural collagen cone (Col-C). Monitoring of the post-traumatic processing. was carried out for 84 days using panel of three lectins (WGA, LABA and CNFA) with different carbohydrate specificities. Results: The lectins demonstrated high variability of binding with constituents of posttraumatic bone tissue. In particular, it was revealed rather selective WGA reactivity with microvascular endothelium, LABA reactivity with macrophages and CNFA with fibroblaststs and osteogenic cells. Injured bone in control and both experimental groups demonstrated distinct rearrangement of lectin receptor sites with drift towards posttraumatic recovery being more prominent after aplication of OCP-N osteotropic material. Traumatic bone injury induced accumulation of macrophages in the site of inflammation, as well as redistribution of lectin receptors in microvascular endothelium. Conclusions: Lectins of different carbohydrate specificities can be recommended for monitoring bone tissue regeneration after posttraumatic injuries.

Bone defect reconstruction following benign bone tumor curettage remains challenging due to limitations of traditional grafts. Autologous bone provides excellent osteoconductivity and osteoinductivity, but it causes donor site morbidity. In contrast, allogeneic and xenogeneic grafts are limited by infection risk and restricted availability. Synthetic substitutes such as hydroxyapatite and β-tricalcium phosphate offer osteoconductivity but lack osteoinductive potential. Octacalcium phosphate (OCP), a precursor of biological apatite, possesses both osteoconductivity and intrinsic osteoinductivity and exhibits greater resorbability than conventional materials. The OCP/gelatin composite (OCP/Gel) was recently approved for clinical use in Japan.This prospective study investigated seven patients who underwent OCP/Gel implantation after curettage of benign bone tumors. No internal fixation was required, and no complications related to the material occurred. Radiographic follow-up demonstrated a gradual decrease in radiolucency at the graft site, and computed tomography at six months confirmed trabecular bone formation in all cases.These findings suggest that OCP/Gel is progressively replaced by new bone and can promote early bone regeneration after tumor curettage. Despite the small sample size, single-center design, and limited defect size, OCP/Gel appears to be a safe and effective bone substitute. Further multicenter studies are warranted to confirm its long-term efficacy and optimal clinical indications.

Octacalcium phosphate (OCP) is a biodegradable material with excellent biocompatibility and osteoinductive activity, showing great promise in bone repair applications. Although silk fibroin (SF) demonstrates osteogenic potential and SF-modified OCP has shown enhanced mineralization and osteogenesis in vitro, the underlying regulatory mechanism remains unclear. In this study, by combining cryo-transmission electron microscopy analysis and density functional theory (DFT) calculations, the SF-modified OCP is revealed that possesses a higher density of dislocations. The hydrophobic amino acid sequence of SF induced the formation of edge dislocations via an "adsorption-epitaxy-extrusion" mechanism, accompanied by changes in adsorption energy, which facilitated the transformation of OCP into hydroxyapatite (HAp) and enhanced osteoinduction. In vitro experiments further confirmed that SF-modified OCP enhanced cytocompatibility, promoted ALP and ARS activity, upregulated osteogenic gene expression, and strengthened osteogenic protein expression. This work proposed a novel strategy for modulating defect structures in bioceramics through organic molecules and demonstrated the potential of dislocation-engineered SF-OCP for bone defect repair.

Abstract This paper series considers the process of hydro-electrochemical saturation in nano-scale porous media. In Part I, we introduced a novel, synchronous, and integrated numerical model for hydro-electro-chemo-dynamics simulation and sensitivity analysis of nanoscale crystallization potential, and validated each of its components separately. In this Part II, we apply this methodology to perform the integrated simulations of complex 2D and 3D nanopore systems that exhibit electrochemical, hydrodynamic, and crystallization phenomena, in pair with sensitivity analysis. The phenomenon chosen for this analysis is the formation of octa-calcium phosphate in the calcium silicate hydrate. A reactive Navier–Stokes–Poisson–Nernst–Planck equation system for three ions types in the moving fluid and in the presence of a dynamic electric field is discretized using lattice Boltzmann methods. Using automatic differentiation, simplified two-dimensional models of open and blind pores as well as a three-dimensional $${\upmu }$$ CT scan of a porous rock are investigated with respect to the influences of electric surface potential, pore width and length, carrier fluid velocity and ion concentrations on octacalcium phosphate saturation. These simulations reveal new previously unknown insights into the crystallization process in nanopores—specifically, that narrow long blind pores with higher surface electric potential promote saturation probability. Moreover, large geometries with bigger pore systems accumulate more ions in their center locally in comparison to the smaller systems.

BackgroundThe term periodontium encompasses the supporting structures around a tooth, including gingival tissue, alveolar bone, cementum, and periodontal ligament. Periodontal disorders are highly prevalent, affecting approximately 95% of the Indian population. Restoring the missing attachment apparatus is the main goal of regenerative therapy in cases of periodontal disease. The reproduction or rebuilding of damaged or lost periodontal tissue to restore the structure and functionality of the periodontium is known as regeneration. This study investigates the effectiveness of autologous sticky bone (ASB), autologous platelet-rich fibrin (PRF), and octacalcium phosphate–coated deproteinized bovine bone material (OCP-DBBM). These materials are being evaluated for their potential to enhance bone regeneration in infrabony defects, which are a significant concern in periodontal therapy. Effective bone regeneration is critical for the successful treatment of periodontal defects, as it can lead to improved clinical outcomes, including better attachment levels and reduced probing depths. This study aims to provide insights into the most effective methods for achieving these goals.ObjectiveWe aim to assess the efficacy of ASB and autologous PRF in conjunction with OCP-DBBM in infrabony defects at 6 months after surgery with regard to radiographic bone fill, reduction in probing pocket depth, and increase in clinical attachment level.MethodsThis randomized controlled clinical trial will be performed on 20 defects in patients diagnosed with stage 2 and 3 grade B periodontitis. It will be a parallel-designed study where group 1 (n=10) will be treated with ASB and group 2 (n=10) will be treated with autologous PRF and OCP-DBBM. One sitting will be required to perform the treatment, and a follow-up checkup will be done at 6 months.ResultsRecruitment procedures started in June 2025. All data are anticipated to be collected by February 2026. Full trial results are anticipated to be analyzed and submitted for publication by March 2026. The study’s anticipated end date is March 2026.ConclusionsBoth treatment approaches are expected to lead to notable gains in periodontal health and bone regeneration. The primary outcome, radiographic bone fill, and the secondary outcomes, clinical attachment level gain and probing pocket depth reduction, are critical indicators of treatment success.Trial RegistrationClinical Trials Registry-India CTRI/2024/06/069603; https://www.ctri.nic.in/Clinicaltrials/pmaindet2.php?EncHid=MTAzODk0&Enc=&userName=International Registered Report Identifier (IRRID)PRR1-10.2196/69666

Polymethylmethacrylate (PMMA) maxillofacial prostheses are widely used in facial bone reconstruction, providing functional restoration, aesthetic rehabilitation, and improved quality of life. However, due to its bioinert nature, PMMA exhibits limited tissue integration. This study aimed to coat PMMA maxillofacial prostheses with hydroxyapatite (HA) to enhance the material’s bioactivity and interaction with biological tissues. Two porous configurations fabricated by additive manufacturing were tested: Prototype A, with ellipsoidal pores, and Prototype B, with a regular hexagonal architecture. Mechanical evaluation demonstrated average values of 33.01 MPa for tensile strength, 3.18 MPa for impact toughness, and 62.65 MPa for flexural strength, confirming structural stability under functional demands. Structural analysis revealed the formation of calcium phosphate phases with low crystallinity, predominantly hydroxyapatite and octacalcium phosphate, while surface examination showed a continuous granular coating with pseudo-spherical agglomerates. Bioactivity assays indicated that the HA-coated prostheses were capable of inducing apatite precipitation, in contrast to uncoated PMMA, which remained bioinert. Prototype A favored permeability and surface area for potential cell adhesion, whereas Prototype B ensured uniform porosity and predictable load distribution. The integration of controlled porous architecture with HA deposition resulted in composite prostheses that combined mechanical robustness with surface bioactivity, representing a promising approach for improved maxillofacial reconstruction.

Patient: Male, 18-year-oldFinal Diagnosis: Alveolar bone atrophySymptoms: MalocclusionClinical Procedure: —Specialty: Dentistry • SurgeryObjective: Unusual or unexpected effect of treatmentBackgroundExtensive bone augmentation using artificial bone substitutes is difficult because of their inferior bone regeneration ability compared with that of autologous bone. However, octacalcium phosphate (OCP) and OCP collagen composite (OCP/Col) are better bone substitutes than other materials. Herein, we report a case of extensive alveolar-bone augmentation using OCP/Col and a titanium mesh for restoration of the occlusion and aesthetics using dental implants.Case ReportAn 18-year-old man with maxillary anterior alveolar-bone deficiency due to a traffic accident was referred to our hospital for dental implant treatment. The bilateral maxillary central incisors were missing, and the labial alveolar-bone volume was insufficient. Radiographic examination and preoperative simulations revealed that the alveolar bone was insufficient for dental implant placement. Bone augmentation was performed using OCP/Col and a custom-made titanium mesh according to the ideal shape determined through simulation. The periosteum was incised to expand the mucosa, and the wound was then sutured. The patient was required to eat soft foods for several days, and movement around the upper lip was restricted using taping. Six months after bone augmentation, reconstruction of the ideal alveolar morphology was confirmed, and dental implants were placed. After the final prosthesis was inserted, the occlusion and esthetics were restored, and the patient’s quality of life significantly improved.ConclusionsIn this patient, an extensive alveolar-bone defect was reconstructed with an ideal alveolar shape using OCP/Col and a titanium mesh. This case report presents the first clinical application of OCP/Col combined with a custom titanium mesh for repairing large alveolar bone defects in the maxillary anterior teeth.

The discovery of solute precursors of crystalline materials,suchas biominerals, recently challenged the classical nucleation theory(CNT). One emerging method for investigating these early-stage intermediatesin solution is dissolution dynamic nuclear polarization (dDNP)-enhancednuclear magnetic resonance (NMR) spectroscopy. Recent applicationsof dDNP to calcium carbonate (CaC) and calcium phosphate (CaP) mineralizationhave demonstrated the feasibility of identifying and tracing veryearly-stage prenucleation clusters (PNCs). However, the structuraldetails remain difficult to resolve as dDNP is mainly limited to simpleone-dimensional NMR detection. To overcome this bottleneck, we hereinintegrate hyperpolarized NMR of PNC with molecular dynamics simulationsand quantum mechanical calculations to gain atomistic structural insightsinto CaP PNCs. By simulating the PNC structures, computing chemicalshift parameters, and comparing these to hyperpolarized NMR “fingerprint”spectra, we demonstrate how to derive models of solution-state structuralensembles of PNC, even when very short-lived. With this approach,we find that the Ca/Pi ratio inside PNC tends to stay closeto 1 independent of pH, while their sizes vary, leading to largerprecursors under more basic conditions. At the same time, phosphatespeciation within PNC was found to be independent of pH, as only monohydrogenphosphates participated in PNC formation. This latter feature alsoentailed a pH-independent local atomistic arrangement of phosphatescoordinating a Ca­(II) center, leading to constant Ca2+–Pi distances of ∼3 and ∼3.6 Å. These ion-to-iondistances agree with those found inside solid CaP phases such as brushite,octacalcium phosphate, or hydroxyapatitea feature hintingtoward the templating function of PNCs. Thus, our method (i) extendsthe methodological scope of hyperpolarized NMR by complementing one-dimensionalfingerprint spectra with full structural models and (ii) sheds lighton key intermediates that have been experimentally underexplored.

Calcium phosphate (CaP) materials are biocompatible and non-toxic to the body. However, they lack biointegration, exhibit a low resorption rate and can cause fibrous encapsulation throughout the implant material. A promising approach for dental or orthopedic regeneration is the use of dicalcium phosphate dihydrate (DCPD) and octacalcium phosphate (OCP), as they are well-suited to bone components. From a novel perspective, these apatites can be used as drug carriers for individuals with low tolerance to common excipients. In this study, the transformation of DCPD into different morphologies in DMEM was investigated using an induced dissolution and reprecipitation reaction solution. The DCPD transformation time was observed to be morphology-dependent and can occur between 48 and 168 h. In the interaction with simulated body fluid (SBF), simulated gastric fluid (SGF) and a combination of both (BFS/SGF), a higher mass loss was observed in SGF (~80%) than in the other fluids (~35%). The structural changes presented in DCPD and OCP before and after immersion in physiological fluids were analyzed by ATR-FTIR, SEM, XRD and EDS. The obtained OCP showed low stability in SGF compared to SBF and SBF/SGF, which indicates that it may be a suitable candidate for drug delivery in the digestive tract.

Formation of Octacalcium Phosphate Coating on the Surface of β-Tricalcium Phosphate Ceramics