Quality Resource Guide –

Periodontal Regeneration 3rd Edition

www.metdental.com

Page 4

capable of differentiating into osteoblasts and other

cell types required for periodontal regeneration.

Nevertheless, multiple clinical considerations,

such as donor site morbidity, have limited the

use of autogenous grafts. Numerous particulate

bone

grafting

materials

are

commercially

available, such as allogeneic bone, xenogeneic

bone, calcium phosphate ceramics, bioactive

glass, coralline calcium carbonate, among others.

Currently, bone allografts are the most widely

used grafting materials in periodontal regeneration

in the United States. Demineralized freeze-dried

bone allograft (DFDBA), or demineralized bone

matrix, is allogeneic bone that has undergone

extensive decalcification and mineral removal.

DFDBA exhibits the capacity to induce bone

formation

(osteoinductive)

nonorthotopic

sites, such as muscle, presumably due to the

exposure of bone morphogenetic proteins.

DFDBA has been shown on a histologic level to

support periodontal regeneration in humans.

14,15

Bone grafts function as structural scaffolds and

matrices for attachment and proliferation of

anchorage-dependent osteogenic cells at the

recipient site. A primary determinant of regenerative

capacity

the

mobilization

pluripotent

mesenchymal stem cells, which have the capacity

to differentiate into a variety of cell types, including

osteoblasts and periodontal ligament fibroblasts,

depending on the recipient site and the type of signals

available.

Recent advances in tissue banking make

it possible to preserve mesenchymal stem cells

and osteoporogenitor cells as part of an allogenic

cellular bone matrix. Allogeneic bone grafts that

have undergone selective depletion of immunogenic

cells while preserving mesenchymal stem and

osteoprogenitor cells may offer the potential to

achieve more predictable and robust regenerative

outcomes, while minimizing risk of allogeneic

rejection.

Current technologies allow for the

selective retention of high numbers of mesenchymal

stem and osteoprogenitor cells. Osteocel® (Ace

Surgical Supply, Inc., Brockton, MA), for example,

is a cryropreserved cellular bone matrix allograft

that is processed to contain a minimum of 50,000

cells/cc with a cell viability of 70% or greater of the

enzymatically released cells.

The bone matrix is

stored on dry ice or at -80°C and must be thawed

prior to clinical application

(Figure 4)

The success of regenerative therapy is influenced

by multiple factors related to the patient, periodontal

defect, and surgical management.

7,19

With the

exception of autogenous bone/bone marrow grafts,

allogeneic cellular bone matrix, and allogeneic

demineralized bone matrix, most bone replacement

grafts are considered passive scaffolds providing

space maintenance and a framework for cellular

migration and tissue formation. Recent attention

has focused on the potential for protein and

peptide-based products (biological mediators) to

improve wound healing and enhance the clinical

benefits of bone replacement grafts. There are

two commercially available dental bone grafts with

biologic components - PepGen P-15™ (Dentsply

Friadent, Mannheim, Germany) and GEM 21S™

(Osteohealth/Luitpold

Pharmaceuticals,

Inc.,

Shirley, NY). PepGen P-15™ is bovine-derived

hydroxylapatite (anorganic bone) that contains a

short polypeptide chain of 15 amino acids, which is

a biomimetic cell binding region of type I collagen.

GEM 21S® is a completely synthetic grafting

system composed of a purified recombinant human

platelet-derived growth factor-BB (rhPDGF-BB) and

ß-tricalcium phosphate (ß-TCP) scaffold. GEM 21S®

is the first dental bone grafting material approved

by the FDA with a recombinant growth factor.

GEM

21S® contains over 1000 times the concentration of

platelet-derived growth factor obtainable in current

platelet rich plasma preparations.

Unlike the particulate bone grafts, Emdogain®

(Straumann USA LLC, Andover, MA) is an enamel-

matrix derivative comprised of porcine proteins

(amelogenins) delivered in a resorbable material

(propylene glycol alginate). Emdogain® is classified

by U.S. FDA as a device (biological material,

dental) and regulated as a bone grafting material.

It is approved for the topical application to root

surfaces as an adjunct to surgery.

The combination

of enamel-matrix derivative and bone grafts may

result in additional clinical improvements compared

with those obtained with enamel-matrix derivative

alone.

Finally, bone grafts can be combined with growth

factors obtained from the serum of a patient. Platelet-

rich preparations (PRP), such as platelet-rich plasma

and platelet-rich fibrin, collected from centrifugation

of serum, provides a source of highly concentrated

autogenous platelets containing growth factors, such

Figure 4

Cellular bone matrix allograft contains mesenchy-

mal stem cells capable of differentiating into cells,

such as osteoblasts, necessary for periodontal

regeneration. Blood from the surgical field is visible

on the instrument (not the bone matrix).

Figure 5

(a)

Platelet-rich plasma provides a source of

autogenous growth factors, which can be admixed

with the bone graft.

(b)

Adhesive properties of

platelet-rich plasma can facilitate graft placement

and containment.

Courtesy of Dr. James Kassolis, Baltimore MD

as platelet-derived growth factor and transforming

growth factor-ß, which are critical for normal

healing.

When admixed with a bone graft, PRP

facilitate graft placement and containment and may

provide beneficial effects in the treatment of intra-

bony defects.

22,23

(Figure 5)