succedaneous tooth moves into the vacated area,new alveolar bone deposited around the erupting succedaneous tooth
The role of underlying connective tissue in maintaining these phenotypes is important. JE can reappear despite its complete excision during periodontal surgery indicates that factors other than a tissue's embryonal genesis are important for its appearance
relative lack of proliferation of the epithelial cell rests of Mallassez.
Development of periodontium. periodontics
Dr. Guru Ram Tej. K (P.G.)
Dept. of Periodontics & Implantology
Mamata Dental College
Overview of tooth development.
Neural crest development.
Development of cementum.
Development of periodontal ligament.
Development of alveolar bone.
Development of gingiva.
Development is the progressive
evolution of a tissue and usually refers to an
increase in its complexity and specialization
Complex biologic processes
Epithelial mesenchymal interactions
Neural crest development
Dental structures (dentin and cementum,) and their
supporting tissues (periodontal ligament and alveolar
bone) are produced by cells originating in the neural
crest. Enamel from the ectodermal cells.
By about 8 days
By 27th day
During the first 3 weeks
By the third week
Neural crest development
During the next few weeks, the ectoderm thickens and
forms raised margins- neural folds
The neural tube
Neural crest cells
Primary epithelial band
After 37 days
Continuous band of thickened epithelium
During the 6th week of
development begins with a
thickening of the oral
epithelium lining the future
dental arches to form the
Although tooth development
is a continuous process, the developmental
history includes several morphologic stages
The bud stage of tooth
development is the stage
at which portions of the
epithelium in the dental
lamina first begin to
aggregate and form an
At 8th week
Proliferate forming a
parabolic- cap like structure
9th -10th week.
Ectomesenchymal cells begin
to proliferate under the dental
papilla (ultimately give rise to
the dentin and dental pulp)
Bell-shaped appearance at 12th week.
The outer enamel epithelium
The inner enamel epithelium
The stratum intermedium
The stellate reticulum
Hertwig's epithelial root sheath
Separates the cells comprising the dental
papilla and dental follicle.
Cells of the inner enamel epithelium induce
adjacent cells in the dental papilla to
differentiate into odontoblasts and
subsequently deposit the root dentin.
Pre functional development
Development of cementum
cells at site of development
Disruption of HERS
Cell-cell: Cell-matrix interactions:
growth factors/ cytokines
Reorganization of cells
Initial cementum formation
The first increment of
against the root
Epithelial cell rests of
of the rootsheath)
can be seen within
the follicular tissue.
Cementum Forming Cells
The cells responsible for cementum
formation may be
Fibroblasts -located within the periodontal
ligament- origin in the dental follicle.
Fiber insertion occurs along the lining of
the bony socket wall.
Root surface-derived and bone-derived
fibers ultimately coalesce in the middle
third of the ligament space to form the
Schematic representation of the
sequential organization of the
periodontal ligament fibers in
developing marmoset teeth. G,free
gingival fibers; A, alveolar crest fibers;
H, horizontal fibers;0, oblique fibers.
(From: Levy BM, Bernick )
Development of oxytalan
fibres and the ground
Fullmer et al.
The alveolar bone
Formed during root
Development is independent of
other portions of the alveolar
Succedaneous tooth germs are located within the same
osseous cavity as their deciduous precursors
During the eruption of a succedaneous tooth: resorption
the walls of the bony crypt,
the roots of the superficial primary tooth,
and the alveolar bone housing the primary tooth.
With the loss of the primary tooth
With the emergence of succedaneous teeth
complete deposition of new alveolar bone
significant remodeling of the whole alveolar process
Development of Gingiva
Composed of a superficial epithelium of
ectodermal origin and an underlying connective
tissue of mesodermal origin. (Listgarten 1972;
Formation of Gingival Sulcus
Begins to form as the
A separation occurs
between the attached
epithelium and the tooth
Epithelial cells derived
from stratum intermedium
also begin to form into
cells with the appearance
of junctional epithelium.
Modalities of tooth-tissue
Gingival tissues (both epithelial and
connective tissue) associate with the tooth
via separate mechanisms.
via an epithelial attachment called the
in health, is usually located at, or coronal
to, the CEJ
attach to the root surface at or below the CE]
via fiber insertion into the cementum of the root
Role of Epithelial-Mesenchymal Tissue
Interactions in Maintaining Tissue Phenotype
Junctional epithelium is initially derived from the
reduced enamel epithelium,
Gingival epithelium originates from the ectodermal
tissues covering the maxillary and mandibular
Two tissues considered to have
distinct origins, phenotypes, and function.
Controlling Influence Of Connective
Tissue Substrate On Epithelial
Connective tissues are considered to play in
important role in regulating the adjacent
If components of palatal and buccal mucosa
are cross-grafted, the pattern of epithelial
differentiation is controlled by the underlying
connective tissue (Ten Cate 1994).
connective tissue of the gingival tissues
does permit epithelial growth and proliferation
ligament connective tissue
suggested to be non permissive for epithelial
growth and differentiation (Mackenzie
explains the inability of junctional epithelium to extend
apically beyond its periodontal connective tissue interface
with the tooth,
Knowledge about the development of these
tissues is important since it will help us understand
better the mechanisms required for inducing repair
and regeneration of damaged tissues.
Carranza, Newman, Takei, Klokkevold:
carranza’s clinical periodontology, 10th Ed. Pg53, Elsevier
Inderbir Singh: Human embryology: 6th Ed.
A R Tencate. Oral HistologyDevelopment, structure and function. 3rd Ed.
Connective tissues of the periodontium:
periodontology 2000; Vol 24: 2000
Regeneration of periodontal tissues:
cementogenesis revisited: periodontol 2000.
Mark Bartold, Sampath Narayanan: Biology
of periodontal tissues: pg 151-161