Carriers in Bone Graft Putty: Collagen, CMC, Hyaluronate, Gelatin, and Alginate — What the Literature Reports

A bone graft carrier is the non-mineral phase of a moldable or injectable bone substitute: a hydrogel, protein, or polymer that binds particulate graft material into a putty, paste, or plug so that the particles are handled and placed as one mass rather than as loose granules. The particles remain the osteoconductive component; the carrier governs how the material behaves from package to flap closure and for some period afterward. In dental products sold in the United States that phase is collagen, carboxymethylcellulose (CMC), sodium hyaluronate, porcine gelatin, polyethylene glycol with glycerin, or a setting calcium sulfate cement. Alginate has a large tissue engineering literature and no dental bone graft product on the US market.

Key takeaways

• PubMed title/abstract searches (September 2026) return 319 records for “carrier matrix”, three for “bone graft binder”, and none for “bone graft carrier”.
• The case for a carrier rests on two of the four PASS principles of Wang and Boyapati (2006): space maintenance and stability.
• Calder et al. (2025) report that collagen, glycerol, poloxamer, and hyaluronic acid carriers resorb within days, with structural collapse of the implanted mass; CMC persists but forms no three-dimensional structure.
• “Alginate hydrogel” has more than 2,100 records, yet no human clinical study as a dental bone graft carrier was identified, and the one large-animal putty-versus-granules comparison (Coathup et al., 2016) favored granules.
• In dental search, “alginate” usually means impression material (217 records) and “encapsulated” usually means fibrous encapsulation (376 records), an adverse outcome.

How the literature names the carrier

The literature has no settled noun for this component. “Carrier matrix” appears in 319 title/abstract records (42 with “bone”), “hydrogel carrier” in 37 with “bone”, “injectable bone substitute” in 101; “bone graft carrier” returns zero and “bone graft binder” three (PubMed, September 2026). D’Este and Eglin (Acta Biomater 2013, PMID 23201020) asked in their title, Sticky excipients or advanced 3-D carriers?, describing hydrogels in calcium phosphate composites as binders for the inorganic phase. Calder et al. (Adv Healthc Mater 2025, PMID 39840481) write “universal carrier matrix”. Labeling uses “carrier” (Citagenix, MTF Biologics, ZimVie) or “binder” (NovaBone). This article uses “carrier”.

Why a carrier: handling, space, stability

Wang and Boyapati (Implant Dent 2006, PMID 16569956) set out four principles for predictable bone regeneration: primary wound closure, angiogenesis, space maintenance, and stability. Two of the four are what a carrier is asked to supply; the vocabulary is established: “handling properties” (758 title/abstract records), “space maintenance” (381), “graft stability” (277), “volume stability” (247).

The problem is documented independently of any product. Zuercher et al., in a five-year randomized trial of block versus particulate bovine bone mineral (Clin Oral Implants Res 2026, PMC13542762), write that “a key limitation of particulate grafts is their susceptibility to displacement” under flap pressure at closure. Wang et al. (Front Bioeng Biotechnol 2023, PMC10282947) add that particulate, powder, and block substitutes have shown poor handling and space maintenance in clinical practice.

Whether a carrier changes the biological outcome is a separate question. In a seven-patient split-mouth sinus floor augmentation study, Knabe et al. (J Funct Biomater 2017, PMC5618282) compared a tricalcium phosphate putty in a hyaluronic acid hydrogel with the same ceramic as granules: both supported bone adequate for implants; six-month volume loss was 14.5 ± 10.3% against 28.4 ± 16.1% (p = 0.39).

Carrier classes in US dental products

Product statements are the manufacturers’ own; the literature column refers to the carrier class, not the named product.

Carrier	US product examples (manufacturer statements)	Origin	What the literature reports
Collagen, 10–20%	Bio-Oss Collagen: 90/10 bovine bone mineral and porcine collagen. MinerOss X Plug: 80/20 bovine particulate and bovine type I collagen. Zcore Form: 90/10 porcine particulate and porcine collagen. RegenerOss Bone Graft Plug: 80/20 carbonate apatite and bovine type I collagen. Three of the four makers say the collagen keeps particles in the defect.	Animal (porcine or bovine)	Degrades within a few days (Calder 2025).
Carboxymethylcellulose (CMC)	C-Graft Putty: demineralized bone matrix in a CMC hydrogel from cotton linters.	Plant (cotton linters)	With calcium sulfate and demineralized bone in rat calvaria, 33.7 ± 12.9% new bone at 28 days against 31.7 ± 9.5% without CMC (Reynolds 2007); forms no three-dimensional structure (Calder 2025).
Sodium hyaluronate	DBX Putty, Inject, Paste, Mix, Strip: cortical demineralized bone in sodium hyaluronate (Putty 31% bone by weight), designed to resist movement under irrigation. In Europe, botiss’s cerabone plus hydrates with hyaluronate into “sticky bone”; GUDID lists only cerabone and Jason membrane under botiss (2026-09-11).	Microbial fermentation (per manufacturer)	Degrades in about five days (Calder 2025); a hyaluronic acid TCP putty performed comparably to granules in human sinus augmentation (Knabe 2017).
Gelatin	RegenaVate DBM Putty: demineralized bone and cortical cancellous chips in porcine gelatin, formable at 45 °C, solid at body temperature.	Animal (porcine)	Methacrylated gelatin used experimentally to stabilize Bio-Oss particles (Wang 2023); no dental clinical comparison identified.
Polyethylene glycol and glycerin	NovaBone Dental Putty: 70% calcium phosphosilicate particles in a binder absorbed within 24–72 hours.	Synthetic	Glycerol resorbs within days (Calder 2025).
Poloxamer	DynaBlast, DynaGraft-D (poloxamer reverse-phase medium); manufacturer documentation not examined in this article.	Synthetic block copolymer	Resorbs within days and may occupy inter-particle space (Calder 2025).
Calcium sulfate cement	Bond Apatite, 3D Bond+: biphasic calcium sulfate cement in a dual-chamber syringe, said to set in the presence of blood and saliva; membrane contraindicated, per manufacturer.	Synthetic mineral	Widely used binder and expander; with demineralized bone, 31.7 ± 9.5% new bone at 28 days in rat calvaria (Reynolds 2007).
Alginate	None: no 510(k) or GUDID record carries “alginate” under dental codes LYC, NPM, NUN, orthopedic codes MQV, MBP, or barrier codes NPL, NPK (openFDA, 2026-09-11).	Plant (brown seaweed)	In vitro, rat, rabbit, and sheep studies only; in sheep, 16.69 ± 2.7% new bone at twelve weeks against 33.56 ± 3.53% for granules, p = 0.043 (Coathup 2016).

What the literature reports as limitations

The most direct account is Calder et al. (2025). The authors list collagen, glycerol, CMC, poloxamer, and sodium hyaluronate as the carriers used commercially in putty products; they state that collagen, glycerol, poloxamer, and hyaluronic acid resorb or degrade within a few days, that such rapid loss leads to structural collapse of the implanted product and uneven distribution of particles, and that CMC lacks three-dimensional structural properties. Their alternative, a synthetic thermoresponsive hydrogel, was tested in mice (n = 24), rabbits (n = 9), and an 11-participant pilot randomized trial of ridge preservation; several authors are employees of the developer, as the paper discloses. NovaBone’s 24-to-72-hour binder agrees on the timescale. D’Este and Eglin (2013) framed the same distinction: a hydrogel that only sticks particles together is an excipient, not a carrier.

The counterweight: rapid carrier loss has not been shown to reduce bone formation in the comparisons available; Reynolds et al. found comparable new bone with and without CMC in rats, and Knabe et al. found no penalty for the hyaluronic acid putty in humans. Carriers change handling and early stability; bone formation falls in the same range as without them.

Alginate: what is known, what is scarce, and the counter-result

Alginate is an anionic polysaccharide from brown seaweed that gels on contact with divalent cations such as calcium, which underlies its use as an injectable hydrogel (Lee and Mooney, Prog Polym Sci 2012, PMC3223967; Hernández-González et al., Carbohydr Polym 2020, PMID 31826429). “Alginate hydrogel” appears in more than 2,100 title/abstract records, alginate with “bone tissue engineering” in 516, and dozens of reviews cover alginate in bone regeneration, among them Chen et al., Int J Mol Sci 2024. The same reviews are explicit about limitations: mammals lack alginase, so the polymer is not enzymatically degraded; ionically crosslinked gels lose stability in physiological fluids as calcium exchanges for monovalent ions; unmodified alginate lacks cell-adhesive ligands and is biologically inert unless modified with peptides such as RGD or blended with gelatin or collagen; its stiffness is low. Chen et al. add disintegration in physiological environments and low biological activity.

The dental literature is thin. Alginate with “guided bone regeneration” returns 33 records, with “periodontal regeneration” 29, with “sinus augmentation” or “ridge augmentation” 3, with “socket preservation” none; alginate with “bone graft” or “bone grafting” plus a dental, oral, alveolar, periodontal, or maxillofacial term returns 17. No systematic review and no human clinical study of alginate as a dental bone graft carrier were identified. What exists is in vitro (BDJ Open 2020, PMC7419530), in rats (Front Bioeng Biotechnol 2020, PMC7047753), and in rabbits (J Maxillofac Oral Surg 2024, PMC11607265).

The one direct putty-versus-granules comparison in a large animal points the other way. Coathup et al. (J Biomed Mater Res B 2016, PMID 26118665) implanted porous hydroxyapatite granules, the same hydroxyapatite in an alginate polysaccharide fiber gel putty, or that putty with bone marrow aspirate into 36 critical-size defects in sheep femoral condyles. At six weeks bone apposition was significantly lower with the putty than with granules (p = 0.014); at twelve weeks new bone occupied 33.56 ± 3.53% of granule defects and 16.69 ± 2.7% of putty defects (p = 0.043). The authors concluded that the alginate carrier delayed bone formation and that its degradation rate needed optimizing before injectable use. The model is orthopedic and the formulation one of many, but it remains the clearest datum on record. One naming trap: Algipore, AlgOss, and C Graft are phycogenic hydroxyapatite from calcareous marine algae (Gopal et al., Oral Maxillofac Surg 2025, PMID 41075015), not alginate.

Two words that mislead in dental search

“Encapsulated” is not neutral in implantology. “Encapsulated bone graft” returns two title/abstract records; “fibrous encapsulation” returns 376, and the phenomenon is an adverse outcome. Nowzari et al., describing seven patients with migrating bovine xenograft particles, list encapsulation alongside migration and displacement among the complications (J Indian Soc Periodontol 2022, PMC8936023). A surgeon reading “encapsulated graft” is likely to picture a fibrous capsule around a failed graft.

“Alginate” has the mirror-image problem. In dentistry the word denotes the hydrocolloid impression material: 217 title/abstract records pair alginate with “impression material” against 54 that pair it with “bone graft”, of which 7 also carry a dental, alveolar, periodontal or implant term (PubMed search, September 11, 2026). The FDA record agrees: of 85 510(k) records with alginate in the device name, 31 are dental impression materials (product code ELW), and most of the rest are wound dressings and liquid bandages.

Why we wrote this

This site is published by Meddent Innovative Concepts, which is developing ALGINAGRAFT™, a bone graft concept with an alginate-based carrier. The author is the inventor and patent holder of that technology and the founder of the company, and has a financial interest in how alginate carriers are perceived. ALGINAGRAFT™ has not been cleared or approved by the U.S. Food and Drug Administration or any other regulatory authority, has not been evaluated in bench, preclinical, or clinical testing, and is not available for sale or clinical use; no data on its properties exist and none are claimed here. The brand is named in this paragraph only. Alginate is discussed above solely as the published literature describes it, including the results that count against it.