CRANIOFACIAL AND DENTAL TISSUE - 3D Bioprinting and Nanotechnology in Tissue Engineering and Regenerative Medicine - page 187

9.2.1.1 Dental Disease
Statistics show that 100% of adults have dental caries, and it is estimated that 15-20% of adults
between the ages of 35-44 suffer from severe periodontal disease that will result in tooth loss. Dental
disease is cumulative with age, resulting in 30% of people aged 65-74 becoming fully edentulous. The
mandible and maxilla of the edentulous naturally atrophy with time, becoming much thinner and more
susceptible to fracture.
9.2.1.2 Trauma
The primary cause of death in people under 40 years of age is trauma. Approximately 25,000 people per
year require surgery to fix maxillofacial trauma in the United States. Maxillofacial trauma results from
assault, motor vehicle collisions, falls, and sporting accidents. The relative incidence of these causes
has been shifting. With increasing widespread use of airbags and seatbelts, the number and severity of
maxillofacial fractures from motor vehicle collisions has been decreasing. On the other hand, as the
population is aging and the elderly are seeking active lifestyles, the number of fractures from falls is
trending up ( Martinez et al., 2014 ).
9.2.1.3 Aging
As people age, the collagen framework loosens, the dermis thins, there is a cumulative solar elastosis,
and muscles and bones of the face thin and atrophy. These result in an inferomedial descent of the soft
tissue and the stigmata of aging including wrinkles, furrows, jowls, decreased dental show, the down-
ward tilt of the corners of the mouth, and sunken cheeks.
9.2.1.4 Cancer
In the United States more than 40,000 people are diagnosed with oral and pharyngeal cancers each year
(The Oral Cancer Foundation; http://oralcancerfoundation.org/facts/). An additional 3.5 million people
are diagnosed with a new skin cancer (basal cell, squamous cell, or melanoma). A majority of these
occur in the highly sun-exposed craniofacial region. The ablation of craniofacial malignancies often
requires resection of multiple surrounding tissue types (skin, subcutaneous fat, bone, and mucosa), en-
suring adequate margins but leaving the patient with exposed bone, vessels, and nerves and defects that
cannot be closed primarily. Radiation treatments further complicate wound healing by compromising
the local vasculature.
9.2.1.5 Congenital
In the U.S. approximately 38,000 infants undergo surgery each year for the treatment of congenital de-
fects. One in 1000-2000 infants are born with sporadic or inherited craniosynostosis (fusion of cranial
plates), which can lead to a malformed cranium, intracranial hypertension, and restricted brain growth.
An additional 1:1000 children are born with cleft lip and palate. Certain syndromes can result in hy-
poplasia of the maxilla (i.e., Apert's or Crouzon's) or mandible (i.e., Treacher Collins or Pierre Robin
Sequence) and airway compromise. Furthermore, many are born with microtia or contour irregularities
which they find aesthetically displeasing (CDC, 2008).
9.2.2 STANDARD-OF-CARE PROCEDURES
The standard of care for these craniofacial defects and deformities, with the exception of teeth, has his-
torically centered around manipulating and transplanting the patient's own tissues. Autogenous tissue
has the characteristics of an ideal biomaterial: biocompatible, nontoxic, nonallergenic, noninflammatory,