Massachusetts Institute of Technology
Harvard Medical School
Brigham and Women’s/Massachusetts General Hosp.
VA Boston Healthcare System
2.79J/3.96J/BE.441/HST522J
DENTAL TISSUE REPLACEMENT
AND REGENERATION
M. Spector, Ph.D. and I.V. Yannas, Ph.D.
Image source: OCW
Dental Implant Designs
and Materials
Sapphire
Alumina
Titanium
Carbon
Images removed due to copyright considerations.
Alumina
Alumina
Carbon
Blade Implant
Images removed due to copyright considerations.
“Commercially pure”
Titanium
Two-Stage Design;
to shield the artificial
root from loading
during the initial
stage of healing
Images removed due to copyright considerations.
Dental Implant Designs
and Materials
Hydroxyapatite-
Coated Implants
Images removed due to copyright considerations.
Secondary
dentin
Dental
Caries
Osteodentin
Calcium
hydroxide
liner
Secondary
dentin
Tissue Engineering
Enamel Regeneration
Dentin Regeneration
Pulp Regeneration
Restorative Materials
Ceramics: porcelain
Metals: amalgam, Implants
Polymer: composite, gutta percha
ELEMENTS FOR TISSUE
REGENERATION/ENGINEERING
CELLS Autologous, Adult
(pulp and bone marrow
stromal stem cell)
MATRIX Collagen-GAG
CYTOKINES Regulation of phenotype
Matrix biosynthesis
Tissue Engineering of Complex Tooth Structures
on Biodegradable Polymer Scaffolds
? Cells dissociated from porcine third molar tooth
buds.
? Cells seeded onto PLA fiber mesh and implanted in
rats for 20 to 30 wks.
? Resulting tooth structures contained dentin
(odontoblasts), a well-defined pulp chamber, putative
cementoblasts, and a morphologically correct enamel.
? Results suggest the presence of epithelial and
mesenchymal dental stem cells in porcine third molar
tissues.
C.S. Young, et al. J Dent Res 81(10): 695-700, 2002
Growth of Porcine Enamel-, Dentin-, and
Cementum-Derived Cells in Collagen-GAG
Matrices In Vitro
Unerupted Porcine Premolars and Molars
? Lower mandibles from 6-month old pigs.
? In aseptic environment, mandibles were split
in half, soft tissue removed, and overlying
bone from lingual side chiseled away.
? Exposed teeth were excised and gingiva
removed.
Marty-Roix R, et al., Tiss. Engr. (In press)
MATERIALS AND METHODS
Cell Isolation
Dentin - from developing cusp tips. Mineralized
enamel removed and pulp cut away.
Enamel - Mineralized enamel removed from cusp
tips and chiseled into small pieces.
Cementum - from erupted 2nd molars and
unerupted premolars. Chiseled away from tooth
and into smaller pieces. Pulp removed with
sterile gauze.
Pulp - from base of teeth and cut into small pieces
with scalpel.
MATERIALS AND METHODS
Methods of Cell Culture
? Cell Isolation from Digested Tissue
– Tissue digested for 12 hours in collagenase.
– Suspension filtered, and cells plated into tissue
culture dishes.
? Explants/Cell Outgrowth
– Small pieces of tissue plated onto tissue culture
dishes.
COLLAGEN-GAG MATRICES
? Type I (bovine tendon)
? Type II (porcine)
? Chondroitin 6-sulfate
Image removed due to copyright considerations.
Image removed due to copyright considerations.
1mm
? Freeze-dried
? Dehydrothermally cross-linked
500μm
IV Yannas, et al. PNAS, 1989
Cell Cultures at Confluence; Digested Tissue
Ameloblasts Pulp Cells
Images removed due to copyright considerations.
Odontoblasts
Cementoblasts
DENTAL TISSUES
Tissue-Specific Matrix Molecules
? Enamel Amelogenin
? Dentin Dentin Matrix Protein-1
? Cementum ?
? Pulp Cells ?
Amelogenin Immunohistochemistry
Amelogenin
Negative ControlPre-ameloblasts
Images removed due to copyright considerations.
Dentin
Odontoblasts
Amelogenin Immunohistochemistry; Passage 1
Ameloblasts; Digested Tissue
Ameloblasts;
Outgrowth from Explants
Images removed due to copyright considerations.
Neg. Control
Neg. Control
1 day
Amelogenin
Immunohistochemistry of
Ameloblast-Seeded
Collagen-GAG Matrices
Images removed due to copyright considerations.
7 days
Images removed due to copyright considerations.
1 day
DMP-1 Immunohistochemistry
of Odontoblast-Seeded
Collagen-GAG Matrices
7 days
28 days
SUMMARY
? Cells can be isolated from digested tissue and
grown from explants: enamel, dentin ,
cementum, and pulp.
? Cells display distinctive characteristics.
? Ameloblasts expanded in monolayer and grown
in collagen-GAG matrices express amelogenin.
? Odontoblasts in collagen-GAG matrices express
DMP-1