11/7: Teeth Flashcards
What are teeth grossly divided into?
Root and crown
What is the portion of the tooth embedded in bone?
Tooth root
What is the pat of jaw that a tooth is embedded in?
Alveolar ridge
What is the tooth socket called?
Alveolus
What is the portion of tooth that projects into oral cavity?
Crown
What are teeth protected by?
A layer of highly mineralized enamel, covers crown
What is enamel?
a hard, translucent substance, containing < 1% organic material & 96-98% hydroxyapatite
What is enamel secreted by?
Tall, columnar ameloblasts of enamel organ
When do ameloblasts degenerate?
When the tooth erupts, after which enamel cannot be replaced by new synthesis
What do secretory ends of ameloblasts form?
Single, large process, Tome’s process (microtubules and secretory vesicles)
Explain enamel mineralization
Non-uniform, resulting in highly calcified enamel rods or prisms - roughly hexagonal
What is enamel separated by?
Interprismatic material
Where do enamel rods extend from?
Ameloblasts at enamel surface to dentino-enamel junction
What is the bulk of tooth composed of?
Less mineralized dentine
What is dentine secreted by?
Odontoblasts of dental papilla as non-mineralized pre-dentine
Explain the components of dentine?
Chemically similar to bone, but more mineralized; ~70-80% hydroxyapatite crystals
What plays a key role in mineralization of dentine matrix (like odontoblasts)?
Matrix vacuoles (Ca2+ and PO4-)
What else does dentine contain?
Type I collagen and GAG’s
How is dentine arranged?
In dentine tubules
What are dentine tubules?
Hollow, parallel tubes radiating from pulp cavity
What do dentine tubules contain?
Long, rod-like cytoplasmic process of odontoblasts (aka Tome’s fibers)
What does the central pulp cavity contain?
Support structures - sensory nerves and blood vessels
What is dentine innervated by?
Myelinated nerves
Describe dental pulps origin
Mesodermal in origin
What does dental pulp resemble?
Primitive mesenchyme
What does dental pulp contain?
Sellate 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?
Cementum
What is cementum manufactured by?
cementoblasts
What do cementoblasts mature into?
Cementocytes
What do cementocytes that lie against the surface of the periodontal ligament produce?
New cementum by appositional growth
What is similar to osteoblasts/cytes structurally and functionally?
Cementocytes
What is the region of the tooth between root and crown?
Neck of tooth
What is the neck of tooth protected by?
Masticatory oral mucosa called gingiva
What does the gingiva cover?
Upper portion of alveolar ridge
What is gingiva sometimes divided into/
Attached gingiba
What does attached gingiva cover?
Upper alveolar bone and free gingiva (forms cuff ~ neck of tooth)
What is the spave between free gingiva and crown called?
Gingival sulcus or crevice
What is the gingiva lined by?
Cervicular epithelium
What is crevicular epithelium easily breached by?
Bacteria -> periodontal disease, gingivitis
What is tissue that surround and support tooth referred to as?
Periodontium
What is included in periodontium?
Epithelium, cementum, peridontal ligament, and alveolar bone
How is cementum layer anchored to bone of alveolus?
With gibers of periodontal ligament or membrane
What is periodontal ligament composed of?
Dense, collagenous fibers, called Sharpey’s fibers