CRANIOFACIAL AND DENTAL TISSUE - 3D Bioprinting and Nanotechnology in Tissue Engineering and Regenerative Medicine - page 196

9.4 BONE TISSUE ENGINEERING STRATEGIES
Tissue engineering strategies have the potential to augment traditional restorative approaches that uti-
lize transplanted tissues and bone substitute materials. Some key considerations in the development of
tissue-engineered strategies for craniofacial/dental tissue are as follows: (1) are there any stem cells
that can be used; (2) can aesthetic demands be met; (3) can tissue-engineered constructs be used as part
of a composite strategy; (4) can adequate vascularization demands be met; and (5) can the high risk of
infection in the oral and nasal cavities be managed ( Moioli et al., 2007 ). These aspects have also been
discussed in detail by Mikos et al., (2006) ( Table 9.3 ). Craniofacial tissue-engineered strategies are
likely to be required to regenerate more than one tissue phenotype at the same time ( Moioli et al., 2007 ;
Rahaman and Mao, 2005 ).
Bone tissue engineering-based strategies for craniofacial/dental tissue regeneration can be divided
broadly into three main categories based on the scaffold, cellular, or growth factor component that plays
the major role in the expected regeneration phenomenon. Bioreactor preculture or surface functionalization
of these implants may also be used to limit the attachment of cells to a specific type and to help those cells
commit to play a role after implantation by having a functioning tissue type (e.g., by producing extracel-
lular matrix) or by prevascularizing the tissue via coculture with endothelial cells ( Temple et al., 2013 ).

Table 9.3 The key aspects to be considered during the development of tissue engineering
strategies for oral and craniofacial tissues
Permission pending from ( Mikos et al., 2006 )

Tissue engineering aspect Challenge

Wound healing environment Regeneration of lost tissues in essentially “contaminated” conditions.

Scaffold design requirements • Injectability.

• Abilitytoencapsulatecells.
• Abilitytohardentoastatewhichmimicsthemechanicalpropertiesofbone.
• Degradationataratefastenoughtoallowtheingrowthofsurroundingtissue.

Cell-surface interactions Ability to selectively promote the adhesion of specific cell populations while

excluding the invasion of others.

Growth-factor delivery • Increasedeficiencybyloadingphysiologicalamountsofgrowthfactorsinto

a scaffold allowing for improved cost-effectiveness.
• Spatialandtemporalcontroloverthereleaseofmultiplegrowthfactorsusing
multiple kinetic rates.

Assessment Development of clinically relevant animal models for in vivo qualitative and

quantitative assessment of implanted materials.

Scale-up • Abilitytousetissue-engineeredconstructsinlargedefectswherediffusional

limitations may limit the viability of encapsulated cells.
• Abilitytodeterminethetranslatabilityofresultsseenwith in vivo animal
models in the clinical setting.

Specific clinical issues which
remain unaddressed

• Controloverthemorphologyofregeneratedbone.
• Periodontalligamentanchorageandeffectivegingivalsealaroundtitanium
dental implants.
• Regenerationofentireteethwithsupportingstructuresinextractionsockets.