Embryology of Dental Structures
Embryonic Stages
 Ovum: 1st week/fertilization
 Embryo: 2-8 weeks
o Stomodeum (Primitive Mouth): develops in 3rd week
o Buccopharyngeal membrane ruptures: 4th week
o Primary Dentition Initiated: 6-8 weeks
 Fetus: 9-36 weeks
o Permanent Dentition Initiated: 20th week in utero till 10th month after
birth
 Fertilization » morula » blastocyst » trophoblast » embroyblast
Embryo
 Ectoderm: nasal cavity, enamel, nervous system, appendage of skin, hait
and nails and glands
 Mesoderm: skeletal system, muscles, tongue, blood and lymph cells,
kidney, dentin, cementum, pulp
 Endoderm: pharynx, stomach, intestines, bladder, vagina
Brachial Arches
 1st (Mandibular): mandible, lower lip, muscles mastication, anterior portion
of the tongue, maxillary process
 2nd (Hyoid) Facial muscles, posterior portion of the tongue, sides and front
of the neck, portion of the hyoid bone, portion of the muddle ear
 3rd.: posterior portion of the tongue, portion of the hyoid bone
Odontogenesis
Tooth Development (occurs over 2 yrs): bud, cap, bell, detinogensis,
amelogenesis, apposition of dentin and enamel, eruption, function
Ectoderm
 oral epithelium » enamel organ » enamel
 dental lamina
Mesenchyme Cells
 dental papilla » dentin and pulp
 dental sac » cementum and periodontal ligaments
Tooth Germ
 enamel organ, dental papilla dental sac
Epithelial Components (4 distinct cell layers)
 OEE



IEE
STI
STR
Layers of Dentin
 Primary- mantle and circumpupal dentin
 Secondary- starts after tooth the formation of the apical foramen, which
occurs once tooth is in occlusion
 Tertiary- reparative dentin
Structural Components of Dentin
 Dentin tubule
 Peritublular (intratubular) dentin
 Intertubular dentin
-Tome’s Granular Layer: layer of dentin that underlies cementum, covers the
root
Principle Cells of the Pulp
 Odontoblasts
 Fibroblasts
 Undifferentiated mesenchymal cells
 Macrophages
 Lymphocytes
Functions of the Pulp
 Inductive
 Formative
 Protective
 Nutritive
 Reparative
Five Funtional Stage of Ameloblasts
 Morophogenesis
 Organization and differentiation
 Secretion
 Maturation
 Protection
-Hypoplastic Enamel: strong but pitted, yellow to grey in color, thin enamel
-Hypocalcified Enamel: weak, white/yellowing spotting, insufficient number of
crystals deposited in enamel
-Chemical Composition of Enamel: 96% inorganic, 4% organic
-Chemical Composition of Cementum: 65% inorganic, 23& organic, 12% water