Hydroxyapatite (HA) has been a focal point of research since the 1980s because of its chemical resemblance to bone minerals, notable biological activity, and osteoconductivity (Dunaev et al., 2014; Lei et al., 2017). Stoichiometric HA features a dense crystalline network of PO₄ tetrahedra, each centered around a P⁵⁺ ion coordinated by four oxygen atoms. These tetrahedra form interconnected columns, resulting in two distinct types of unconnected channels within the lattice. HA is commonly synthesized via methods such as solution–precipitation and sol–gel (Ben-Arfa et al., 2017; Mirzaee et al., 2016). These characteristics render HA a preferred bioceramic for periodontal bone tissue repair. Porous chitosan (CS) membranes were fabricated with or without HA using the simple freeze gelation (FG) technique with two different solvent systems: acetic acid (ACa) and ascorbic acid (ASa). Fourier-transform infrared (FT-IR) spectroscopy confirmed the presence of hydroxyapatite and its interactions with chitosan. All the membranes supported cell proliferation, and long-term matrix deposition was supported by the HA-incorporated membranes. These CS and HA composite membranes have potential for use in GTR for periodontal lesions (Qasim et al., 2015). Small intestinal submucosa (SIS) was coated with hydroxyapatite (SIS-HA) and gelatin methacrylate hydroxyapatite (SIS-Gel-HA) using biomineralization and chemical crosslinking. SIS was found to upregulate M2 marker expression, and both SIS-HA and SIS-Gel-HA enhanced the osteogenic differentiation of PDLSCs through the bone morphogenetic protein (BMP)-2/Smad signaling pathway, demonstrating superior in vitro osteogenic activity. In vivo, SIS-HA and SIS-Gel-HA yielded denser and more mature bone, with the highest BMP-2 and Smad expression. SIS-HA and SIS-Gel-HA demonstrated enhanced immunosteogenesis coupling, representing a promising periodontal tissue regeneration approach (Cheng et al., 2024). HA bioceramics with micro-nano-hybrid surfaces (mnHA [a hybrid of nanorods and microrods]) can promote cell adhesion, proliferation, alkaline phosphatase (ALP) activity, and expression of osteogenic/cementogenic-related markers, including Runx2, ALP, osteocalcin (OCN), cementum attachment protein (CAP), and cementum protein (CEMP). Various strategies have been employed to fabricate scaffolds with differing pore parameters (Carotenuto et al., 2022).

The TIPS technique, supported by the salt-leaching process, was employed to investigate the influence of HA content in PLLA/HA scaffolds on various properties, including pore structure, density, porosity, mechanical characteristics, and osteoblast proliferation (Zeinali et al., 2021). It was found that an increased HA content within the scaffold (up to 75 wt%) correlated with enhanced roughness of the pore wall surfaces, elevated porosity (96%–98%), and a higher proliferation rate of osteoblast cells. A more recent study conducted by the same research group demonstrated that apatite whiskers (HAP) completely covered the pore wall surfaces of PCL/HAP scaffolds, resulting in significantly increased surface roughness (Petersen et al., 2018). These scaffolds exhibited high porosity (approximately 90%) along with heterogeneous pores characterized by two distinct size ranges: larger pores with diameters of up to 600 µm and smaller pores located within micropore walls measuring up to 50 µm. Moreover, L-lysine modification of hydroxyapatite enhances the bioactivity of PCL/HAP scaffolds by promoting osteoblast proliferation and differentiation while simultaneously improving mechanical properties and increasing surface roughness of the wall pores. Compared to smooth surfaces, it is suggested that a rough topography may more effectively mimic the mineralized interface encountered by cells adhered to the native bone ECM. These results suggest that HA bioceramics containing mnHA are promising grafts for periodontal tissue regeneration (Mao et al., 2015).

TCP, a well-studied calcium phosphate, exists in three polymorphs: α, β, and α′, each stable at different temperatures and notable for their bioactivity and degradability (Li et al., 2017). Calcium phosphates are favored as bone substitutes because of their biocompatibility and osteointegration (Stavropoulos et al., 2010). Although sintered hydroxyapatite is widely used in bone-tissue engineering, it is minimally resorbed. In contrast, β-TCP offers superior resorbability in both animal and human studies (Kon et al., 2000). Its three-dimensional structure enhances cell attachment, proliferation, and osteogenic differentiation (Nade et al., 1983; Zambonin et al., 2000). In a recent study, porous β-tricalcium phosphate (β-TCP) scaffolds were fabricated by integrating digital light processing (DLP) printing techniques with an in situ crystal growth process. These bioceramic scaffolds, featuring both macro- and micropores, were produced through DLP printing. Subsequently, an in situ crystal growth process was employed to generate micro-/nano-scale surface topographies. The resulting micro-/nanostructured scaffold enhanced the proliferation and differentiation of rat bone mesenchymal stem cells (rBMSCs), demonstrating significant capacity for skull bone regeneration in a rat model (Di Luca et al., 2016). Native bone tissue exhibits a structural gradient that can be observed radially in long bones and axially in flat bones due to variations in bone density and pore parameters from cancellous to cortical bone. Drawing inspiration from this natural architecture, Di Luca et al. developed three-dimensional polycaprolactone (PCL) scaffolds that feature an axial gradient in pore size and overall porosity using the “fused deposition modeling” (FDM) method. This scaffold notably enhanced osteogenic differentiation of human mesenchymal stem cells (hMSCs), particularly benefiting those residing within larger pores (Diloksumpan et al., 2020). Additionally, three-dimensional printing technology was utilized to create two types of 3D bioceramic scaffolds with distinct internal architectures—either exhibiting a designed porosity gradient or maintaining a uniform pore distribution. Nery and Lynch (1978) first reported the use of TCP-based bone grafts for periodontal defects in 1978. Owing to its high biodegradability, osteoconductivity, and osteoinductivity, β-TCP is a promising scaffold material for bone tissue engineering and is frequently used as an alternative to autologous bone grafts (Zhang J. et al., 2014). β-TCP microspheres with different diameters were fabricated via a solid-in-oil-in-water (S/O/W) emulsion method. BMSCs were co-cultured in vitro with β-TCP microspheres, and SEM and confocal microscope analyses were performed to discover that β-TCP microspheres efficiently promoted BMSC attachment and bone-related gene expression. The co-cultured BMSCs and microspheres were successfully implanted subcutaneously into nude mice for 8 weeks, and abundant new bone-like structures had formed between the β-TCP microspheres, implying that β-TCP microspheres can be used as a cell carrier and bone graft substitute material (Li et al., 2017).

The extensive application of β-TCP in bone tissue regeneration demonstrates its promising potential for periodontal tissue regeneration. The β-TCP scaffold seeded with bone marrow mononuclear cells (BM-MNCs) from C57BL/6J mice, when transplanted into the thigh muscle of syngeneic mice, demonstrated accelerated bone formation and enhanced periodontal tissue regeneration (Uchikawa et al., 2021). Owing to its excellent physical and chemical properties, β-TCP can be integrated with various biomimetic materials to enhance periodontal tissue regeneration. Different concentrations of β-TCP-loaded chitosan hydrogels (0%, 2%, 4%, or 6% β-TCP, 10% β-glycerol phosphate, and 1.5% chitosan) with cells can promote periodontal tissue regeneration (Tan et al., 2023). In the periodontal defect model of beagle dogs, the application of Retro mineral trioxide aggregate (MTA) or a combination of Retro MTA + β-TCP covered with a collagen membrane led to the regeneration of periodontal tissues (Fakheran et al., 2019).

Bioactive glass (BG), a class of synthetic alloplastic materials with a silicate base, possesses the distinctive capability to bond with mineralized hard tissues, such as bone, in physiological environments. Developed by Hench et al. in 1969, BG marked a significant advancement in dental applications during the mid-1980s when Clark et al. successfully utilized it in a clinical trial for alveolar ridge preservation in edentulous patients (Välimäki and Aro, 2006). It was not until the 1990s, however, that BG was first used for the treatment of periodontal lesions (Zamet et al., 1997). Recent research has identified BG as an osteoinductive agent capable of inducing osteoprogenitor cell migration into graft structures and promoting cell differentiation by influencing the gene expression of undifferentiated cells (Kargozar et al., 2018; Kargozar et al., 2017). It demonstrated bioactivity along with a relatively high mechanical strength that exhibited only a gradual decline, even under load-bearing conditions within the body (Shue et al., 2012). Schepers and Ducheyne (1997) introduced the term “osseostimulation” to describe the bone-formation process facilitated by BG (Schepers and Ducheyne, 1997). The most extensively used BG over the past 50 years is 45S5 glass, which is characterized by a low SiO₂ content and high Na₂O and CaO contents, along with a high CaO/P₂O₅ ratio, enhancing its reactivity with biological fluids (Vitale-Brovarone et al., 2009). In dental applications, 45S5 glass particulate, commercially known as PerioGlas® (NovaBone Products LLC, Alachua, FL, United States), has been demonstrated to inhibit epithelial cell down-growth and promote alveolar bone regeneration (Mengel et al., 2003; Subbaiah and Thomas, 2011). A multi-functional and sustained-release drug delivery system (MB/BG@LG) was developed by encapsulating methylene blue (MB) and BG into a lipid gel (LG) precursor using Macrosol technology. In addition, in vitro and in vivo experiments showed that MB/BG@LG can effectively promote periodontal tissue regeneration by reducing the inflammatory response and promoting cell proliferation and osteogenic differentiation (Chen et al., 2023). The incorporation of nano-BG glass-ceramic particles into alginate composite scaffolds enhances the ALP activity of human periodontal ligament fibroblast cells cultured on these scaffolds. Mesoporous bioactive glass (MBG) is extensively utilized in bone tissue repair and drug delivery applications. However, the occurrence of burst release of drugs and poor compatibility with other materials has limited its broader application. Modifying MBG with a polymer brush presents an effective strategy to enhance its properties. In this study, an alginate (ALG)-modified MBG was synthesized, and the effects of ALG on the characteristics of MBG were systematically investigated. The results demonstrate that ALG significantly improves drug loading efficiency, prolongs drug release duration, and facilitates the orderly deposition of apatite on the surface of MBG (Yao et al., 2022). These results suggest that biocompatible composite scaffolds are promising for periodontal tissue regeneration (Srinivasan et al., 2012).

Calcium sulfate (CaS), commonly referred to as “plaster of Paris,” was first introduced as a synthetic bone graft material by Van Meekeren in 1892. This compound exists in three forms differentiated by the number of water molecules within its crystalline structure: anhydrates, dihydrates, and hemihydrates. The hemihydrate form, which dissolves rapidly, is predominantly utilized in medical-grade products and is available in two variants, α and β. Upon complete degradation in biological fluids, calcium sulfate leaves calcium phosphate deposits that promote bone growth (Shaffer and App, 1971; Zhao et al., 2021). Currently, calcium sulfate and its composites are primarily employed in dentistry and maxillofacial surgery as injectable bone fillers for sinus augmentation and alveolar bone regeneration in small periodontal defects (Thomas and Puleo, 2009).

Because of their predominant biocompatibility, bioactivity, and sealing ability, calcium silicate (CSi)-based bioceramics have been widely used in endodontic treatment, including MTA, Biodentine, BioAggregate, and iRoot BP Plus (Parirokh et al., 2018). MTA is characterized by low or no toxicity and excellent biocompatibility. It stimulates repair by allowing cellular adhesion, growth, and proliferation on its surface. MTA possesses good antibacterial properties, but it does not exhibit significant cytotoxic effects on host cells. They possess a large specific surface area and a nanoporous or hollow structure, which contribute to their elevated drug-loading capacity. Additionally, these materials demonstrate pH-responsive drug release behavior and favorable drug release characteristics. Consequently, they hold significant promise for applications in drug delivery. The calcium silicate-based drug delivery systems are characterized by prolonged drug-release times, which can considerably extend the therapeutic effects of administered drugs. Another notable advantage of these systems is their pH-responsive nature regarding drug release; this feature renders them an ideal platform for targeted drug delivery (Zhu et al., 2017). Additionally, it induces cementogenesis while regenerating the periodontal ligament, leading to bone formation.

In recent years, several CSi-based cements have been proven to be potential bioactive materials for bone-substitute applications, and some of them exhibit excellent in vitro and in vivo osteogenesis and odontogenesis (Chen Y. W. et al., 2016). CSi is a common material with excellent mechanical strength (Zhang W. et al., 2021). In addition, CSi cement not only exhibits a good osteoconduction effect but also reduces inflammatory markers in primary human dental pulp stem cells (hDPSCs). CSi-based cements can also stimulate the osteogenic differentiation of various stem cells, such as bone marrow stromal cells, adipose-derived stem cells, human dental pulp cells, and periodontal ligament cells. CSi and β-TCP composite collagen membrane (Retro MTA + β-TCP) has been shown to effectively promote periodontal tissue regeneration in the periodontal defect model of beagle dogs, demonstrating significant potential for periodontal bone regeneration (Fakheran et al., 2019). A fast-setting and controllable degradation of magnesium–calcium silicate (Mg–CSi) cement should be developed via the sol–gel method, and a mechanism should be established to stimulate hPDLSCs using Mg ions. The proliferation, alkaline phosphatase, odontogenesis-related gene (DSPP and DMP-1), and angiogenesis-related protein (vWF and ang-1) secretion of hPDLSCs significantly increased when the Mg content of the specimen was increased. The results of this study suggest that Mg–CSi materials with this modified composition could stimulate hPDLSC behavior and serve as effective bioceramics for bone substitutes and hard tissue regeneration applications, as they stimulate odontogenesis/angiogenesis (Chen et al., 2015; Chen Y. W. et al., 2016).

CS, a linear polysaccharide derived from chitin, exhibits notable properties, such as biodegradability, biocompatibility, antimicrobial effects, low antigenicity, hygroscopicity, and moisturizing properties (Bee and Hamid, 2025). Typically sourced from crustacean exoskeletons, chitosan comprises randomly dispersed β-(1,4)-glucosamine and N-acetyl-D-glucosamine units. The deacetylation process of chitin, first identified by Rouget in 1859 and later termed “chitosan” by Hoppe-Seyler in 1894, has demonstrated significant biomedical applications (Duymaz et al., 2025). In recent years, CS has been advocated for GTR/GBR applications because of its exceptional properties, including biocompatibility, biodegradability, anti-inflammatory and antibacterial properties, hydrophilicity, mucoadhesive characteristics, membrane-forming ability, flexibility, and cost-effectiveness. CS has been demonstrated to facilitate cellular adaptation and proliferation of various essential cell types involved in regenerating periodontal tissue, such as osteoprogenitor cells, osteoblasts, periodontal ligament fibroblasts, and gingival fibroblasts. Seol et al. (2004) demonstrated that CS sponges enhance the proliferation and differentiation of osteoblasts. Similarly, Klokkevold et al. (1996) verified that CS promotes the differentiation of osteoprogenitor cells, specifically MSCs, and potentially aids osteogenesis and bone formation. CS nanogels showed no cytotoxicity toward hGF cells at concentrations of 10–80 μL/mL (M et al., 2023).

In a separate study, CS promoted hPDL cell proliferation at concentrations of 2,000, 1,000, 100, and 50 μg/mL compared to the control group. The morphology of hPDL cells cultured with CS indicated no apoptosis, highlighting its non-toxic properties. Additionally, CS supported initial osteoblast attachment and spreading over fibroblasts, which could be advantageous in GBR procedures for bone regeneration by promoting osteoblast attachment and proliferation. In patients with periodontitis, chitosan implantation has been shown to reduce gingival inflammation due to its antimicrobial characteristics (Xu C. et al., 2012). Yeo et al. (2005) illustrated that a nonwoven chitosan membrane effectively enhances bone and cementum regeneration in surgically induced one-wall intrabony defects in beagle dogs, underscoring its potential in GTR and GBR. Furthermore, a CS/MW/Mel scaffold, a blend of chitosan and mesoporous wollastonite loaded with melatonin, was investigated for biomedical applications (Wang et al., 2025). The mHA/CS scaffold demonstrated enhanced osteoblast differentiation at both the cellular and molecular levels, as evidenced by the increased expression of key osteogenic markers, such as Runx2, Type I collagen, and osteocalcin. CS possesses certain inherent disadvantages, including a high degradation rate and low mechanical strength. When hydroxyapatite is combined with chitosan to form a composite scaffold, the resulting material retains the advantageous properties of enhanced biocompatibility and improved mechanical strength (Rodríguez-Vázquez et al., 2015). Additionally, the scaffold exhibited proangiogenic properties, facilitating vascularization, which is essential for tissue regeneration. This study further revealed the inhibitory effects of the mHA/CS scaffold on the growth of periodontal pathogens. When loaded with 20 μg/mL of recombinant human amelogenin (rhAm), the composite scaffold significantly boosted ALP activity and upregulated the expression of Runx2, OPN, and DLX-5 genes and proteins in vitro (p < 0.05). The GdPO₄/Fe₃O₄/chitosan hybrid scaffold facilitated tumor ablation by enabling rapid heating under near-infrared laser irradiation. The mesoporous structure exhibited a diameter of 7 nm, and its specific surface area measured 33.95 m²/g (Liao et al., 2020). Their large pores and directional structure promoted cell migration and attachment, thereby enhancing bone tissue regeneration via the BMP-2/Smad/runt-related transcription factor 2 pathway (Merkel et al., 2023; Zhao et al., 2020). Furthermore, the scaffold effectively stimulated the formation of cementum-like tissues in vivo (Liao et al., 2020). These findings suggest that the mHA/CS scaffold loaded with 20 μg/mL rhAm has the potential to inhibit the growth of periodontal pathogens while promoting the formation of bone and cementum-like tissues (Table 4).

Natural polymers, particularly chitosan, serve as a diverse range of drug carriers due to their degradation capabilities. Non-toxicity and high biocompatibility are additional specific properties that make chitosan an ideal candidate for drug delivery systems. Chitosan can be modified into various formulations tailored to specific functions and modes of administration. Furthermore, the protonated amino groups present on D-glucosamine in the chitosan structure enable it to adhere to negatively charged mucus layers through electrostatic interactions, allowing penetration into deeper epithelial layers (Aguilar et al., 2019; Bakshi et al., 2020; Qin and Li, 2020). Due to its mucoadhesive properties, chitosan has been utilized as a vehicle for administering drugs via nasal, ocular, buccal, and pulmonary routes (Bernkop-Schnürch and Dünnhaupt, 2012; Khutoryanskiy, 2011; Singh et al., 2023). However, the insolubility of chitosan in physiological environments poses a challenge for effective drug delivery; this limitation can be addressed through chemical modifications such as carboxymethylation, acetylation, thiolation, and quaternization (Chen K. et al., 2017; Wang W. et al., 2020).

Polylactic acid (PLA) serves as an ideal polymer scaffold for dental, oral, and craniofacial tissue engineering owing to its hydrolytic degradation into lactic acid, a natural human metabolite (Diaz-Gomez et al., 2020). To enhance the scaffold performance, PLA can be combined with durable polymers, such as PEEK, via selective laser sintering to improve bioactivity, biocompatibility, and cytocompatibility (Feng et al., 2018). Additionally, blending PLA with PCL through 3D electrospinning enhances mechanical properties and promotes bioactivity and osteogenic differentiation (Yao et al., 2017). PLA scaffolds with stromal-derived factor-1 offer sustained release and promote endothelial cell proliferation and neovascularization, thus underscoring the potential of 3D-printed PLA constructs for bone regeneration (Singhvi et al., 2019). A novel biomimetic strategy employs Janus-structured porous PLA membranes (PLAMs) created via unidirectional evaporation-induced pore formation and self-assembled bioactive metal-phenolic network (MPN) nanointerfaces. Through the use of PLGA microspheres loaded with IL-4 (IL-4-PLGA), the composite hydrogel scaffold facilitated the transition of macrophages from the M1 phenotype to the M2 phenotype during the early induction phase. Additionally, it demonstrated a sustained anti-inflammatory effect mediated by PLGA microspheres containing kartogenin (KGN-PLGA) (Cheng et al., 2022). PLA serves as a carrier for doxycycline (Doxy) and nano-hydroxyapatite (nano-HAP), facilitating the gradual release of these substances through its resorption process. Consequently, it is anticipated that PLA will exhibit limited antibacterial properties. The enhanced antibacterial effect observed in the tested nanofibers, which were loaded with half the concentration of Doxy (5.04 µg) compared to the Doxy micro-compresses (10 µg), was evidenced by the larger diameters of the inhibition zones (Andrei et al., 2022). In vitro, MPN modification significantly reduced pro-inflammatory macrophage polarization in murine bone marrow-derived macrophages, stimulated angiogenesis in human umbilical vein endothelial cells, and enhanced the adhesion, migration, and osteogenic differentiation of human periodontal ligament stem cells. In vivo, PLAM-MPN implantation significantly accelerates bone repair in rat periodontal defects (Zhang Y. et al., 2023). This bioactive nanointerface within a Janus porous membrane has diverse capabilities to control cell physiology and promote bone regeneration, showing promise as a membrane for clinical applications in GTR and GBR.

Poly (lactic-co-glycolic acid) (PLGA), a copolymer of lactic and glycolic acids, is widely used as a synthetic biomaterial for drug and growth factor delivery and as a barrier in GTR/GBR. Its degradation rate can be adjusted by varying the lactic-to-glycolic acid ratio, owing to the differing hydrophilicities of the monomers (Washington et al., 2017). In vitro tissue engineering studies have compared various PGA-based polymers, such as PGA–PLA, PGA–PCL, and PGA–poly-4-hydroxybutyrate (P4HB). Among these, the PGA–PLA and PGA–P4HB scaffolds showed superior tissue formation compared to PGA–PCL, likely due to an optimal balance between scaffold degradation and tissue formation, thereby preserving mechanical integrity (Generali et al., 2017). PLGA’s excellent biocompatibility and tunable degradation properties make it versatile for periodontal regeneration applications, including barrier membranes, bone grafts, and delivery systems (Sun et al., 2017). Tetracycline, a widely utilized antibacterial agent, was effectively incorporated into PLGA membranes (Owen et al., 2010). The release profiles demonstrated an initial burst phase during the first week, followed by a sustained drug release over a duration of 14 days. This pattern is advantageous for achieving high antibiotic concentrations in the early stages while ensuring an adequate dose throughout the entire healing process. Notably, the incorporation of tetracycline did not alter the morphology of PDLSCs seeded onto the membranes. Kim et al. (2007) investigated the in vivo release profile of tetracycline-loaded PLGA membranes. The results indicated that sustained tetracycline release occurred with elevated concentrations during the initial 7 days; additionally, a greater extent of tissue attachment was observed compared to PLGA membranes alone. Azithromycin (AZM) was encapsulated in PLGA microspheres (AZM@PLGA) using single emulsion solvent evaporation and then coated with silk fibroin (SF) via electrostatic adsorption to mitigate AZM’s initial burst release (Ouyang et al., 2025). AZM@PLGA-SF microspheres significantly reduced periodontal inflammation and restored periodontal tissue health in vivo. The mechanically formulated microspheres modulated the inflammatory microenvironment in periodontal tissues by reducing pro-inflammatory cytokines (tumor necrosis factor-α, IL-6, interferon-γ, IL-2, and IL-17A) in gingival crevicular fluid while increasing anti-inflammatory cytokines (IL-4 and IL-10). In a rat model of periodontal defects, the superparamagnetic iron oxide nanoparticle (SPION)/PLGA scaffold enhanced IL-10 production and decreased NLRP3 and IL-1β release following Porphyromonas gingivalis infection, resulting in superior periodontal regeneration compared to the PLGA scaffold alone. This antibacterial SPION/PLGA scaffold exhibited anti-inflammatory and anti-adhesive properties, aiding in infection control and promoting periodontal tissue regeneration through immune modulation (Washington et al., 2017).

Alginate, a polysaccharide derived from brown algae, is used as a hydrogel in 3D bioprinting and tissue engineering because of its cost-effectiveness, wide compatibility, and similarity to proteins in the ECM. Alginate polymerization is rapid and typically occurs within seconds to minutes of exposure to divalent cations, allowing for various ion-doping options. The introduction of methacrylate groups enables hydrogel production through light-induced radical polymerization. However, the inherent structure of alginate lacks peptide-binding sites for cellular interactions, such as arginine–glycine–aspartate (RGD) and YIGSR peptides (Tolmacheva et al., 2024). Therefore, alginate is commonly combined with other cell-adhesive polymers, such as collagen, and functional polymers, such as agarose or hyaluronic acid, by incorporating an ECM-based protein or RGD peptide sequence to enhance cell adhesion and proliferation. The loading of the drug (spermidine) via dynamic bonding presents a promising avenue, offering a straightforward, cost-effective, and efficient strategy for the sustained release of pharmaceuticals while enhancing the viscoelastic properties of hydrogels (Zhang S. et al., 2023). The drug-loadable calcium alginate hydrogel system is a potential bone defect repair material for clinical dental applications (Chen L. et al., 2017). Bovine serum albumin (BSA) can be directly stored within the 3D pore network structure of hydrogels. However, the positively charged functional groups in BSA can interact with the carboxyl groups present in alginate, leading to the formation of BSA/alginate complexes. Consequently, the release of BSA from these hydrogels is sustained as hydrogel degradation progresses (Zhao et al., 2009). Calcium alginate hydrogels, thus, possess the ability to combine with drugs or proteins through various mechanisms, rendering them highly suitable for drug delivery applications. Collagen provides additional benefits, including low immunogenicity and the promotion of bone regeneration. The use of collagen matrices has been shown to influence osteoblast behavior in various hydrogels (Tharakan et al., 2022). To expedite gelation, post-bioprinting self-healing, and subsequent stabilization via secondary crosslinking, alginate was subjected to methacrylation and oxidation, followed by ionic crosslinking using an eggshell model (Jeon et al., 2022). To enhance alginate hydrogels for bone tissue engineering, inorganic particles, such as bioglass and kaolin, or organic materials, such as cells, drugs, and human allograft tissue, can be integrated (Bhattacharyya et al., 2024; Bhattacharyya et al., 2023; Gharacheh and Guvendiren, 2022). The CS/alginate hydrogel exhibits certain unavoidable limitations, including a high degradation rate and low mechanical strength (Hu et al., 2019; Zupančič et al., 2019). Furthermore, research indicates that the incorporation of carbon nanotubes (CNTs) into the composite scaffold enhances its mechanical properties, potentially making it suitable for periodontal tissue regeneration (Carletti et al., 2011). Consequently, compared to bare hydrogel CS/AL composites, CNT/CS/AL demonstrates superior mechanical and antibacterial properties. Studies have indicated that an RGD-coupled alginate scaffold promotes the differentiation of oral MSCs toward an osteoblast lineage both in vitro and in vivo, as evidenced by the expression of the osteogenic markers Runx2, ALP, and osteocalcin. In summary, these findings represent the first evidence that MSCs from the orofacial tissue, when encapsulated in RGD-modified alginate scaffolds, have the potential for craniofacial bone regeneration (Gharacheh and Guvendiren, 2022). The use of an hPDLSC-based medium enhanced the osteogenic differentiation of hPDLSCs in the Alg + Fib + hPL construct, offering a promising xeno-free strategy for delivering hPDLSCs to boost dental, craniofacial, and orthopedic regenerations (Qiu et al., 2022).

Gelatin methacryloyl (GelMA), akin to the native ECM, features multiple RGD sequences for cell adhesion and MMP-degradable motifs for cell remodeling (Klotz et al., 2016). As a photo-crosslinked hydrogel, GelMA undergoes radical polymerization initiated by light, eliminating the need for potentially harmful chemical cross-linkers (Klotz et al., 2016). Despite its remarkable characteristics, it is primarily constrained by its limited mechanical strength, as certain tissue types inherently exhibit high mechanical stiffness. Although the application of elevated GelMA concentrations can enhance mechanical strength, this improvement comes at the expense of porosity, degradability, and three-dimensional (3D) cell attachment (Sakr et al., 2022). The tunable mechanical properties and favorable biological traits of GelMA make it a versatile scaffold for diverse biomedical applications (Sakr et al., 2022). Studies have shown that GelMA-based scaffolds enhance cell viability and promote osteogenic/odontogenic differentiation of dental stem cells, including dental pulp stem cells (DPSCs), PDLSCs, and stem cells from the apical papilla (SCAPs) (Zhu et al., 2023). In addition to serving as a cell delivery carrier in bioprinting, GelMA facilitates drug and growth factor delivery owing to its degradability. FT-IR spectroscopy confirmed the successful incorporation of irradiated chlorpromazine (CPZ) into the hydrogel matrix. The release profiles of chlorpromazine demonstrated sustained release exclusively in hydrogels containing 1 mg/mL of CPZ. Furthermore, the hydrogel exhibited significant antimicrobial activity against MRSA bacteria compared to penicillin. These findings underscore the potential of CPZ loaded during the photopolymerization process within hydrogels as an effective antimicrobial agent with sustained release properties, rendering it suitable for combating resistant bacterial strains (Tozar et al., 2024). Park et al. (2020) developed a bioink by conjugating BMP peptides to GelMA and found that the BMP-mimicking peptide remained in the bioprinted structure for over 3 weeks and significantly increased odontogenic gene expression in hDPSCs. Pan et al. (2020) evaluated a GelMA hydrogel containing human PDLSCs both in vitro and in vivo, noting enhanced PDLSC proliferation and differentiation within the hydrogel, along with new bone formation in rat alveolar defects treated with hydrogels. GelMA hydrogels have also been improved by using nano-hydroxyapatite (Chen X. et al., 2016). Human PDLSC constructs significantly enhanced osteogenic differentiation, resulting in increased mineralized tissue formation in vivo in a mouse model. GelMA has been combined with materials, such as polyethylene glycol diacrylate (Ma et al., 2017). In diabetic mice, GelMA hydrogels with VH-EVs (Gel-VH-EVs) effectively promoted wound healing by enhancing local blood supply and angiogenesis, potentially by activating the HIF-1α/vascular endothelial growth factor (VEGF)A signaling pathway (Wang Y. et al., 2022). Additionally, GelMA/CuSNP hydrogels accelerate alveolar osteogenesis and vascular genesis, successfully treating periodontitis within 4 weeks in a rat model (Yang et al., 2025).

Polysaccharide hydrogels have emerged as pivotal in bone tissue engineering and regenerative medicine primarily because of their efficacy in enhancing bone repair via cellular and drug delivery. They provide a hydrophilic 3D matrix that enhances osteocyte viability and promotes new bone formation. These hydrogels are extensively used in tissue engineering and wound healing owing to their superior biocompatibility, controlled degradation, and versatile structure (Gonzalez-Fernandez et al., 2022). Their porous polymeric frameworks and high hydration levels emulate the native ECM, supporting cellular proliferation, differentiation, and tissue repair. Furthermore, their biodegradable nature, customizable chemistry, low toxicity, and minimal immune response render them ideal candidates for sustained drug release. In scaffold-based applications, polysaccharide hydrogels induce a foreign body response similar to that of soft tissues, closely mimicking the natural ECM (Taghipour et al., 2020).

Polysaccharide hydrogel scaffolds leverage several key mechanisms to facilitate bone regeneration. First, the hydrogel exhibits low immunogenicity and contains multiple functional groups in its backbone that serve as attachment sites, preventing the displacement of bone cells and therapeutics by blood flow, thereby enabling bone cell proliferation at the fracture site (Koons et al., 2021). Second, the scaffold incorporates MSCs and various osteoinductive proteins, including BMP-2, transforming growth factor-β (TGF-β), and VEGF (Aravamudhan et al., 2013; Gugliandolo et al., 2021; Xu X. et al., 2012). Third, the polysaccharide hydrogel surface is highly microporous, which enhances vascularization and stimulates innate osteogenic processes (Gonzalez-Fernandez et al., 2022). Scaffold-based polysaccharide hydrogels possess porous structures that promote bone regeneration. Studies have demonstrated the remarkable mechanical properties and bone-regenerative capacity of polysaccharide hydrogels. Kolk et al. (2012) integrated regenerated cellulose nanofibers into a chitosan-based polysaccharide hydrogel that enhanced the proliferation and differentiation of osteoblasts. Polysaccharide-based hydrogels were doubly integrated with hydroxyapatite (HAp) nanoparticles and calcium carbonate microspheres (CMs) under physiological conditions. Furthermore, the composite gel scaffolds exhibited favorable sustained drug release and antibacterial properties, as confirmed by calculations of drug release and evaluations of antibacterial activity (Ren et al., 2018). Overall, microporous polysaccharide hydrogels offer excellent biocompatibility, biodegradability, self-repair capabilities, and injectability, making them promising candidates for bone tissue engineering applications.

Decellularized extracellular matrix (dECM) hydrogels are increasingly used in tissue engineering, particularly for in vitro organoid development. This intricate macromolecular framework plays a vital role in modulating cellular adhesion, movement, specialization, and functional activity, thereby influencing tissue growth and maintenance (Zhang H. et al., 2021). Among commercial ECM products, Matrigel®—derived from murine tumor secretions—remains widely used due to its rich composition of basement membrane components, including laminin, type IV collagen, entactin, and heparan sulfate. Various tissue sources, such as human, porcine, bovine, and murine tissues, have been processed to yield dECM using mechanical, chemical, or enzymatic decellularization methods (Crapo et al., 2011). The resulting dECM can be gelled by temperature modulation, ionic strength adjustment, pH variation, or chemical crosslinking. As biomimetic materials, dECM-based constructs offer a tissue-specific microenvironment that promotes specialized cell functions and enhances natural regeneration (Gattazzo et al., 2014). Decellularization effectively eliminates cellular material and immunogenic components while retaining key structural proteins (e.g., collagen, elastin, and fibronectin) and macromolecules (e.g., proteoglycans and glycosaminoglycans) (Keane et al., 2015).

The dECM is extensively utilized in regenerative medicine as a scaffold material, owing to its exceptional biological activity and excellent biocompatibility. Advanced manufacturing techniques, such as 3D printing and electrospinning, have been employed to produce materials/scaffolds based on dECM that can replicate the distinct characteristics of periodontal tissues (Schmidt-Schultz and Schultz, 2005). Multiple strategies have been developed to enhance the mechanical strength of the dECM (Jiang et al., 2021). These include functionalized scaffolds embedded with cells that facilitate the harvesting of scaffold-supported dECM through a process of decellularization and crosslinked soluble dECM that can be utilized to form injectable hydrogels for periodontal tissue repair (Liang et al., 2023). This expansion of dECM applications has facilitated the clinical translation of dECM-based materials for periodontal regeneration. Consequently, the dECM serves as a crucial source of bioactive material to initiate the repair of periodontal tissue and regeneration of the periodontium (Papadimitropoulos et al., 2015). For instance, bone dECM serves as a reservoir of pro-inflammatory cytokines, growth factors from the TGF-β family, various bone morphogenetic proteins (BMPs), and angiogenic growth factors, such as VEGF, thereby inducing osteoinduction by controlling different stages of bone regeneration (Wang S. et al., 2022). The immunomodulatory activity of dECM is robust, leading to a reduction in the secretion of pro-inflammatory factors by M1 macrophages and a decrease in local inflammation in Sprague–Dawley rats. In a critical-size model of periodontal defects, the bioprinted module significantly boosted the regeneration of hybrid periodontal tissues in beagles, particularly the anchoring structures of the bone–ligament interface, well-aligned periodontal fibers, and highly mineralized alveolar bone (Yang et al., 2023).

The urinary bladder matrix and SIS are dECM biomimetic materials endorsed by the FDA to create regenerative biomimetic materials for damaged skin, muscle, and gastrointestinal tissues (Brown-Etris et al., 2019). SIS, a commonly used decellularized tissue, shows promise for soft tissue repair but requires enhancement for bone tissue regeneration. Gou et al. (2019) utilized pig SIS as a collagen membrane to guide tissue regeneration. In a rat cranial defect model, SIS dECM facilitated bone tissue regeneration, resulting in an increased bone volume fraction and tissue regeneration, suggesting the potential for bone regeneration in periodontal defects.

Decellularized bone powder, a common periodontal tissue engineering material, is clinically used in the form of dECM granules (Figure 5). These granules are often combined with hydrogels and a guiding tissue regeneration membrane to enhance periodontal regeneration (Suzuki et al., 2023). Datta et al. (2021) used decellularized bone granules within a chitosan-based hydrogel containing human amniotic mesenchymal stem cells (hAMSCs) to stimulate bone regeneration. Intrinsic growth factors present in decellularized bone granules promote robust cellular viability, proliferation, and osteogenic differentiation of human amnion-derived stem cells (Datta et al., 2021). This biomaterial shows promise for application in periodontal tissue engineering because of its ability to effectively preserve the intricate ECM components found in native tissue, offering optimal cues for the regeneration and repair of damaged periodontal tissue. Son et al. (2019) treated tooth slices from human molars with sodium dodecyl sulfate and Triton X-100, effectively removing nuclear components while preserving the structure and composition (Son et al., 2019). The T-dECMs supported PDLSC regeneration near the cementum by expressing cementum- and PDL-related genes. These findings demonstrate that dentin dECM enhances MSC proliferation and differentiation and show promise for periodontal regeneration in tissue engineering. Dental-derived dECM has been used successfully to promote dental tissue repair (Jeon et al., 2022; Liang J. et al., 2020). The development of soluble dECM, 3D printing, and other advanced fabrication techniques has helped improve the fidelity and strength of dECM-based 3D scaffolds (Park, 2019), focusing on the spatial management in the defect area (Kim et al., 2020; Varoni et al., 2018; Yang et al., 2023). Meanwhile, due to the abundance of certain functional groups in dECM materials—such as hydroxyl, acyl, peptide bonds, and hydrogen bonds—these materials facilitate drug loading through crosslinking reactions (Ding et al., 2023). Notably, this includes amide crosslinking and interactions between aldehyde groups and the amine groups of lysine or hydroxylysine (Gou et al., 2019).

The treated dentin matrix (TDM) exhibits strong odontogenic/osteogenic potential and has been demonstrated to regenerate periodontal ligament-like tissues, including perforating fiber-like tissues, in a beagle canine alveolar socket orthotopic transplantation model. Meanwhile, TDM has the ability to provide sustained drug release, and xenogeneic TDM equipped with the immunomodulatory drug rosiglitazone can achieve a periodontal tissue regeneration effect comparable to that of homogeneous TDM (Lan et al., 2021). Surprisingly, TDM could be ground into TDM particles and combined with PCL, which could be used to fabricate personalized biological roots using low-temperature deposition manufacturing 3D printing technology and regenerate periodontal ligament-like tissue in a beagle canine alveolar socket orthotopic transplantation model. Owing to the superior personalized matching capability of 3D-printed scaffolds, the TDM-PCL scaffold enables the replication of the “immediate implantation” process in the in situ transplantation experiment of the alveolar socket. Therefore, TDM is a type of dECM that plays an important role in periodontal tissue regeneration (Huang et al., 2023) (Table 6).