J Periodontal Implant Sci.  2013 Dec;43(6):251-261.

Advances in the design of macroporous polymer scaffolds for potential applications in dentistry

• Bencherif
• Braschler
• Renaud P

Abstract

A paradigm shift is taking place in medicine and dentistry from using synthetic implants and tissue grafts to a tissue engineering approach that uses degradable porous three-dimensional (3D) material hydrogels integrated with cells and bioactive factors to regenerate tissues such as dental bone and other oral tissues. Hydrogels have been established as a biomaterial of choice for many years, as they offer diverse properties that make them ideal in regenerative medicine, including dental applications. Being highly biocompatible and similar to native extracellular matrix, hydrogels have emerged as ideal candidates in the design of 3D scaffolds for tissue regeneration and drug delivery applications. However, precise control over hydrogel properties, such as porosity, pore size, and pore interconnectivity, remains a challenge. Traditional techniques for creating conventional crosslinked polymers have demonstrated limited success in the formation of hydrogels with large pore size, thus limiting cellular infiltration, tissue ingrowth, vascularization, and matrix mineralization (in the case of bone) of tissue-engineered constructs. Emerging technologies have demonstrated the ability to control microarchitectural features in hydrogels such as the creation of large pore size, porosity, and pore interconnectivity, thus allowing the creation of engineered hydrogel scaffolds with a structure and function closely mimicking native tissues. In this review, we explore the various technologies available for the preparation of macroporous scaffolds and their potential applications.

Keyword

Hydrogels; Polymers; Tissue engineering

MeSH Terms

Dentistry*
Extracellular Matrix
Hydrogel
Hydrogels
Polymers*
Porosity
Regeneration
Regenerative Medicine
Tissue Engineering
Transplants
Hydrogel
Hydrogels
Polymers

Figure

• 

  Figure 1 Illustration of the fabrication steps of macroporous hydrogel scaffolds using sacrificial porogens. (A) Degradable particles are collected and dispersed in a crosslinkable prepolymer solution. (B) After mixing, the porogen-containing suspension (here, the porogen consists in microspheres) is poured into mold prior to solidification. (C) Gelation occurs during the polymerization while encapsulating leachable porogens. (D) Porogen removal via controlled degradation gives rise to a three-dimensional porous network with interconnected macropores and macrochannels.

• 

  Figure 2 Tissue engineering is a promising therapeutic strategy that combines cells, biomaterials, and microenvironmental factors to induce differentiation signals into transplantable formats and promote tissue repair and/or functional restoration. One major approach to tooth regeneration is based on tissue engineering, which consists of seeding isolated tooth cells on macroporous scaffolding materials in vitro along with biologic therapeutics (e.g., growth factors, genes) and subsequently implanting them into the host site. Dental regeneration includes the repair of the entire tooth structure (enamel, dentin, and pulp), periodontal tissue (cementum and ligament), alveolar bone, blood vessels, and nerves.

• 

  Figure 3 General steps in the preparation of three-dimensionally ordered macroporous (3D-OM) scaffolds by colloidal particle templating. The concept of preparing 3D-OM materials is simple: close-packed colloidal particle are infiltrated with a solution or vapor-phase chemical precursors (A), followed by polymerization and removal of templates by thermal processing, solvent extraction, or chemical etching (B).

• 

  Figure 4 Cryogelation process: monomers and/or polymers are mixed in an aqueous solvent and then the whole system is incubated at subzero temperatures for cryopolymerization and/or gelation, along with ice crystal formation; the ice crystals function then as a porogen during polymerization. After complete gelation, and when incubated at room temperature and washed with water to remove unreacted monomers or polymeric precursors, the ice crystals melt and leave behind large interconnected macropores.

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