Maxillofacial Bone Regeneration Using Tissue Engineering Concepts - Engineered Bone: Tissue Engineering Intelligence Unit - page 183

C HAPTER 13

Maxillofacial Bone Regeneration Using
Tissue Engineering Concepts

Minoru Ueda

Introduction

The bone defect in the maxillofacial region generally can be categorized to three types

according to the size of defects. The first category is the cavitary bone defect which is
less than 3 cm in length and need from 5 to 10 ml of bone tissue for reconstruction. For
such defects, the particular cancellous bone marrow grafting harvested from iliac crest is per-
formed. The second category is the segmental bone defect which is from 3 cms to 6 cms in
length and the bone tissue is from 10 to 15 ml. Such defects are often caused by the resection
of mandible due to the benign tumor. The interpositional grafting of iliac bone is performed.
The third category is the largest bone defect with a free end which is more than 6 cm in length.
It needs approximately 20 ml of bone tissue for reconstruction. Such large bone defect is usu-
ally caused by the hemimandibulectomy due to the oral cancer. The free vascularized
osteocutaneous flap is commonly applied for the reconstruction (Fig. 1).
Autogenous bone grafting is a well established and reliable procedure for reconstruction of
the maxillofacial bone. However, it is associated with substantial morbidity in the donor site
that includes infection, malformation, pain, and loss of function. 1 The complications resulting
from graft harvest have inspired the development of alternative strategies for the repair of
clinically significant bone defects. A previous approach to this problem focused on the devel-
opment of various synthetic materials that might be developed instead of the autogenous bone.
However, most of these synthetic materials were not osteogenic or osteoinductive. Therefore
they can not replace the entire function of living bone. On the other hand, allogenic and
heterogenic materials has been used but they have a risk of disease transmission.
The limitations of previous graft materials have led to the development of tissue engineer-
ing which is, defined as the interdisciplinary field that applies the principles of engineering and
the life sciences toward the development of biological substitutes that restore, maintain, and
improve the function of damaged tissue and organs. 2 Recently these tissue engineering concept
has been developed by using the following factors such as signaling molecule, stem cell and
scaffold (Fig. 2).
In this article, the strategy for maxillofacial bone regeneration using tissue engineering con-
cept is introduced.

Signaling Molecule
The first approach for bone regeneration is to deliver specific signaling molecules. If a safe,
recombinant growth factor could be applied to a biocompatible, resorble carrier and the cor-
rect shape of bone implant could be implanted directly out of a package, all of the previously
stated shortcomings of autogenerate bone grafting would be overcome. The host would gener-
ate its own bone in response to the growth factor.