Cementum, Alveolar Bone, PDL Flashcards
Attachment apparatus
cementum, PDL, bone
Cementum is thickest and thinnest where?
thickest: apex and interradicular
thinnest: CEJ
Where does cementum receive its nerve and nutrients?
from PDL
Does cementum form throughout the life of the tooth?
Yes
How does cementum develop?
from dental sac after disintegration of HERS
What is the cementum matrix?
Cementoid, laid down by cementoblasts created by undifferentiated cells of dental sac. Cemetoblasts may become trapped in matrix and become cementocytes
When does the cementum surround the cementocytes become fully mineralized?
when the matrix reaches full thickness
Sharpey’s fibers
terminal calcified ending of collagen fibers 90 degrees to cementum and bone
Canaliculi
in cementocytes; channels connecting to PDL that diffuse nutrients due to blood supply
Cementum interfaces
Overlay: 15%
Meet: 52%
Gap: 33%, more prone to caries and hypersensitivity
When does cementum repair?
only when trauma occurs
Resorption of cementum occurs through which cell?
odontoclast, NO cementoclast
causes reversal line
occurs during ortho, occlusal trauma, eruption of teeth
Acellular
aka primary; slower rate, no cementocytes, covers cervical 2/3, width does not changes
Cellular
aka secondary; after primary, faster w/ cementocytes, width changes during life, especially at apex, apical 1/3 and interradicular areas
Cementicles
mineralized bodies of cementum found in root surfaces or free in PDL
Cemental spurs
found near CEJ, symmetrical spheres attached to cementum caused by irregular deposition
Hypercementosis
excessive production of cellular cementum at apex of tooth, caused by occlusal trauma or pathological conditions (Paget’s disease, chronic periodical inflammation, compensation for occlusal height)
List tissues in order of most to least calcified
enamel, dentin, cementum, bone, pulp
Does alveolar bone remodel?
Yes; more easily than cementum
Alveolar bone/alveolar process/ridge
contains roots of tooth; if patient has anodontia, this bone is not present
Basal bone
apical to roots, form body of max/mand
Alveolar bone proper/cribriform plate
lining of tooth socket/alveolus, made of compact bone, contains Volkmann’s canals and connected to Haversian system
aka bundle bone due to insertion of fibers
On which side are Sharpey’s fibers thicker, bone or cementum?
thicker on bone side
Lamina dura
alveolar bone proper in radiographs, integrity important for pathology
Supporting alveolar bone
both cortical and trabecular/spongy bone
Interdental septum
bone between neighboring teeth; compact bone, alveolar bone proper, spongy bone
Interradicular septum
aka interradicular bone; alveolar bone proper and spongy bone
Development of the Jawbone
Branchial arch 1, maxilla forms intramembraneously (bone to bone), mandible holds Meckle’s cartilage
Pressure
compression of PDL, narrows and bone resorbs through osteoclasts
Tension
causes bone to be deposited and becomes wider
What can mesial drift cause?
loss of vertical dimension, facial lines, wrinkles
Dehiscence
loss of marginal bone
Fenestration
marginal bone still intact, open window affect
What is a word commonly used to describe bone?
plastic; constantly breaks down and remodels
PDL
attachment of tooth to bone and cementum, fibrous CT, serves as periosteum, develops from dental sac
Functions of PDL
formation, resorption, nutrition (blood vessels), sensory (nerves)
Where does the PDLs vascular, nerve, and lymphatic supply enter?
through the apical foramen
Afferent (sensory) nerves
away from body to brain
Automatic sympathetic
regulates blood vessels
Where are the fibers wider and narrower?
wider: apex and cervical area
narrower: cementum and bone
Interdental ligament
connects teeth in the arch and hold neighboring teeth together; involves muscle memory, also known as transeptal
What does trauma do the PDL?
traumatic forces widen PDL, does not initiate disease but can accelerate progression, increased mobility
Chronic periodontal disease and the PDL
PDL becomes disorganized, loss of Sharpey’s fibers
1st fibers to lose: alveolar crest
Interdental fibers: remain the longest
