Hyaluronic acid (HA) has been reported to have a positive effect on periodontal wound healing following nonsurgical and surgical therapy. However, to date, a few basic in vitro studies have been reported to investigating the potential of HA on human periodontal ligament (PDL) cell regeneration. Therefore, the aim of this study was to investigate the effect of HA on PDL cell compatibility, proliferation, and differentiation in vitro. Either non-cross-linked (HA_ncl) or cross-linked (HA_cl) HA was investigated. Human PDL cells were seeded in 7 conditions as follows (1) Control tissue culture plastic (TCP) (2) dilution of HA_ncl (1:100), (3) dilution of HA_ncl (1:10), 4) HA_ncl directly coated onto TCP, (5) dilution of HA_cl (1:100), 6) dilution of HA_cl (1:10) and (7) HA_cl directly coated onto TCP. Samples were then investigated for cell viability using a live/dead assay, an inflammatory reaction using real-time PCR and ELISA for MMP2, IL-1 and cell proliferation via an MTS assay. Furthermore, the osteogenic potential of PDL cells was assessed by alkaline phosphatase(ALP) activity, collagen1(COL1) and osteocalcin(OCN) immunostaining, alizarin red staining, and real-time PCR for genes encoding Runx2, COL1, ALP, and OCN. Both HA_ncl and HA_cl showed high PDL cell viability (greater than 90%) irrespective of the culturing conditions. Furthermore, no significant difference in both mRNA and protein levels of proinflammatory cytokines, including MMP2 and IL-1 expression was observed. Both diluted HA_ncl and HA_cl significantly increased cell numbers compared to the controlled TCP samples at 3 and 5 days. HA_ncl and HA_cl in standard cell growth media significantly decreased ALP staining, COL1 immunostaining and down-regulated early osteogenic differentiation, including Runx2, COL1, and OCN mRNA levels when compared to control samples. When osteogenic differentiation medium (ODM) was added, interestingly, the expression of early osteogenic markers increased by demonstrating higher levels of COL1 and ALP expression; especially in HA 1:10 diluted condition. Late stage osteogenic markers remained inhibited. Both non-cross-linked and cross-linked HA maintained high PDL cell viability, increased proliferation, and early osteogenic differentiation. However, HA was consistently associated with a significant decrease in late osteogenic differentiation of primary human PDL cells. Future in vitro and animal research is necessary to further characterize the effect of HA on periodontal regeneration.

Nearly three decades have now passed since autologous platelet concentrates (APCs) were introduced into clinical practice. Harnessing the body's innate intrinsic capacity for healing, the concepts of platelet‐rich plasma (PRP) and platelet‐rich fibrin (PRF) emerged to concentrate growth factors and cells at supra‐physiological levels. Nearly three decades ago, Professor Robert Marx demonstrated that PRP—obtained via centrifugation of whole blood with anti‐coagulants—could accelerate healing across a wide range of indications in both dentistry and medicine. Subsequent research showed that eliminating anti‐coagulants, leading to the development of PRF, resulted in an even more natural and faster healing process. In dentistry, APCs have been consistently shown to accelerate healing of both soft and hard tissues, either as standalone treatments or in combination with other biomaterials. PRF, in particular, has demonstrated benefits within several dental applications, spanning from root coverage, periodontal regeneration of intra‐bony and furcation defects, ridge preservation, third molar extraction healing, sinus grafting, guided bone regeneration (GBR), and peri‐implant soft tissue healing. Beyond dentistry, PRF has also proven effective in various medical indications—improving outcomes in the treatment of diabetic ulcers, managing joint pain and cartilage degradation in sports medicine, and enhancing outcomes in esthetic medicine. This review highlights the evolution of APCs, with a focus on their clinical applications and recent technological advancements. These include horizontal centrifugation techniques for PRF and more refined protocols for producing concentrated PRF (C‐PRF). Lastly, the article introduces extended‐PRF (e‐PRF) membranes, created through heat‐induced albumin denaturation, which prolong membrane degradation from the typical 2–3 weeks to up to 4 months. These innovative e‐PRF membranes, composed of albumin gel and liquid PRF (Alb‐PRF), are now being used as alternatives to collagen membranes in routine dental procedures.

Carbonate apatite‐coated calcium carbonate (CO₃Ap/CaCO₃) was fabricated through a dissolution–precipitation reaction using CaCO₃ granules as a precursor to accelerate bone replacement based on superior osteoconductivity of the CO₃Ap shell, along with Ca²⁺ release from the CaCO₃ core and quicker resorption of the CaCO₃ core. In the present study, CaCO₃, 10% CO₃Ap/CaCO₃, 30% CO₃Ap/CaCO₃, and CO₃Ap granules were fabricated and examined histologically to evaluate their potential as bone substitutes. Larger contents of CaCO₃ in the granules resulted in higher Ca²⁺ release and promoted cell proliferation of murine preosteoblasts at 6 days compared with CO₃Ap. Interestingly, in a rabbit femur defect model, 10% CO₃Ap/CaCO₃ induced significantly higher new bone formation and higher material resorption compared with CO₃Ap at 8 weeks. Nevertheless, CO₃Ap showed a superior osteoconductive potential compared with 10% CO₃Ap/CaCO₃ at 8 weeks. All tested granules were most likely resorbed by cell mediation including multinucleated giant cell functions. Therefore, we conclude that CO₃Ap/CaCO₃ has a positive potential for bone tissue engineering based on well‐controlled calcium release, bone formation, and material resorption.

Objective: Bone substitute (BS) size might influence the clinical outcomes of guided bone regeneration (GBR) procedures. The aim of the present study was to investigate the influence of BS size on macrophage (Mφ) and osteoblast behaviors in vitro. Materials and methods: Two different granule sizes (S and M/L) were assessed for four different commercial BSs: deproteinized bovine bone mineral (DBBM), biphasic calcium phosphate type 1 (BCP1), BCP type 2 (BCP2), and carbonate apatite (CO₃Ap). The BSs were compared for their impacts on the cell viability and differentiation potential of THP-1-derived Mφs and human osteoblast-like Saos-2 cells. Results: The smaller granules showed higher material volumes and surface areas than the larger granules. Significantly higher viability of Mφs and Saos-2 cells was observed with the DBBM_L-size granules than with the DBBM_S-size granules. Gene expression experiments in Mφs revealed few differences between the two sizes of each BS, although higher CD206 mRNA levels were observed in the BCP1_L group and the CO₃Ap_M group than in the respective S-size groups on day 1. Only DBBM showed significantly higher mRNA levels of osteogenic markers, including Runx2 and osteocalcin, in Saos-2 cells in the S-size group than in the L-size group. Conclusions: The S-size and L-size DBBM granules exhibited clear differences in cell outcomes: cells cultured on the S-size granules exhibited lower cell viability, higher osteopromotive ability, and no noticeable Mφ polarization changes. Clinical relevance: A smaller granule size might be advantageous due to greater bone regeneration potential in the use of DBBM granules to treat defects.