Oral Cavity and Tooth development -Part 2 Flashcards
what are teeth grossly divided into
root and crown
what is the tooth root
portion of tooth embedded in bone
where is the tooth root located
in part of the jaw called alveolar ridge, in the tooth socket called the alveolus
what is the crown
the portion of the tooth that projects into oral cavity
what is the enamel
a highly mineralized layer that protects the crown
describe enamel
hard, translucent substance, containing less than 1% organic material and 96-98% hydroxyapatite
what does enamel derive from embryologically
ectoderm
what is enamel secreted by
tall, columnar ameloblasts of enamel organ
what are tome’s processes
apical, secretory end of ameloblast
what is the formation of enamel rods due to
enamel mineralization not being uniform
what are enamel rods separated by
interprismatic material
where do enamel rods extend from
ameloblasts at enamel surface to dentino-enamel junction
what is dentin embryologically derived from
mesoderm
what is the bulk of the tooth composed of
dentin
what secretes dentin
odontoblasts of dental papilla as non-mineralized pre-dentin
what is dentin chemically similar to
bone but more mineralized ~70% hydroxyapatite crystals
what does dentin contain
type 1 collagen and GAGs
what is dentin arranged in
dentin tubules
what do dentin tubules radiate from
pulp cavity
what do dentine tubules contain
long rod-like cytoplasmic processes of odontoblasts (Tome’s processes)
what does the pulp cavity contain
support structures such as sensory nerves and blood vessels
what is dentin innervated by
myelinated nerves
what is dental pulp embryologically derived from
mesoderm
what does dental pulp resemble
primitive mesenchyme
what does dental pulp contain
stellate fibroblasts, reticular fibers, collagen and ground substance
what is dental pulp supplied by
capillaries from arterioles running with periodontal ligament
what is the tooth root covered by
a thin layer of cementum
what is cementum embryologically derived from
mesoderm
what is cementum
amorphous, collagen-based, calcified tissue ~45-50% hydroxyapatite, similar to bone
what makes cementum
cementoblasts that mature into cementocytes
what are cementoblasts/cementocytes similar to
osteoblasts/osteocytes
what anchors the cementum layer to bone of alveolus
fibers of periodontal ligament or membrane
what is the periodontal ligament composed of
dense, collagenous fibers called sharpeys fibers
what do sharpeys fibers do
run at an oblique angle to support tooth in socket and allow slight movement of tooth during mastication
what are epithelial rests of Malassez
occasional clusters of epithelial cells within periodontal ligament
what is the neck of the tooth
the region of tooth between root and crown
what protects the gingiva
masticatory oral mucosa
what does the gingiva cover
upper portion of alveolar ridge
what does attached gingiva cover
upper alveolar bone