Lecture 1 Flashcards
what are the other names of periodontium?
attachment apparatus
supporting tissues of the tooth
what are the functions of the periodontium?
attach the tooth to bony tissue of the jaw
maintain integrity of masticatory mucosa
when does the periodontium development occur?
early in the embryonic phase
occurs along with tooth development
where do the cells of periodontium originate from?
neural crest (neural tube)
what happens to the cells of the periodontium?
cells from the neural crest migrate into the first branchial arch
what do the cells of periodontium form?
ectomesenchyme beneath stomadeal epithelium
what does the stomadeal epithelium do?
releases factors which initiate epithelial ectomesenchymal interactions
what do the dental lamina form?
bud stage, cap stage, bell stage
what happens to the ectomesenchyme?
ectomesenchyme condenses around dental organ and forms the dental papilla and dental follicle
what does the dental papilla do?
give rise to dentin and pulp
determines the shape and form of tooth
what does the dental follicle do?
gives rise to periodontium
what forms first in embryogenesis?
crown forms first
what does the outer and inner enamel epithelium proliferate apically and form?
Hertwig’s epithelial root sheath
what forms dentin?
odontoblast
what does the inner cells of root sheath secrete?
enamel related proteins (amelogenins)
what happens to the root sheath?
fenestrates
what contacts the root surface?
ectomesenchymal cells of folicle
what happens to the ectomesenchymal cells of follicle?
amelogin induces differentiation into cementoblast and cementoid forms
what does the fibers of cementoid intermingle with?
immature dentinal fibers
what are the periodontal ligaments formed by?
fibroblast
where do the fibroblast differentiate from?
dental follicle lateral to the cementum
where do the osteoblasts differentiate from?
dental follicle ectomesenchymal cells
what happens to the ectomesenchymal cells?**
remain in mature periodontium and participate in turnover
what is the definition of gingiva?
part of the masticatory mucosa which covers the alveolar process and surrounds the cervical portion of the teeth
what are the three parts of the gingiva?
free gingiva, attached gingiva and interdental papilla
what are synonyms for free gingiva?
gingival sulcus, marginal gingiva, sulcus depth
what are the margins of free gingiva?
extends from free gingival margin and free gingival groove
what is the free gingiva made of?
keratinized epithelium
what s the free gingival margin?
coronal end of gingiva- located 1.5-2mm coronal to CEJ
what is the free gingival groove?
junction between free and attached gingiva
corresponds to CEJ- only found in 30-40% of adults
what are the components of gingival epithelium?
oral epithelium
oral sulcular epithelium
junctional epithelium
where is the oral epithelium?
faces oral cavity
where is the oral sulcular epithelium?
faces tooth surface without contacting it
where is the junctional epithelium? **
provides contact between gingiva and the tooth
what is the macroscopic limit of the free gingiva?
extends from free gingival margin to free gingiva groove
what is the microscopic limit of free gingiva?
extends from free gingival margin to junctional epithelium
what are the characteristics of attached gingiva?
firm texture, coral pink, immobile, keratinized
how does the attached gingiva width vary?
increases with age (passive eruption)
widest in incisors, narrowest in premolars
mandibular lingual- lowest in incisors, widest in molars
what is stippling?
small depressions on the attached gingiva
40% of adults present stippling
what is the mucogingival junction?
junction between attached gingiva and alveolar mucosa
where does the mucogingival junction not exist?
not in the palate
what does the shape of interdental papilla depend on?
the contact relationships between adjacent teeth
width of approximal tooth surfaces
course of CEJ
what is the col?
concavity seen in contact areas of premolar/ molar region
non-keratinized epithelium (similar to junctional epithelium)
what is the oral epithelium?
keratinized, stratified, squamous epithelium (keratinocytes)
what are the layers of the oral epithelium?
basal layer
prickle cell layer
granular cell layer
keratinized cell layer
what is orthokeratinized?
no nucleus
what is parakeratinized
nuclear remnants
what happens from the basal layer to the granular layer?
cytoplasmic tonofilaments and number of desmosomes increase
number of organelles increase
what are the cells of the oral epithelium?
keratinocytes (90%)
clear cells
what are clear cells?
melanocytes, langerhans cells, merkel’s cells
what do melanocytes do?
synthesize melanin pigment
what do langerhans cells do?
defense cells
what do merkel cells do?
sensory
what is the basement membrane?
present between basal layer of oral epithelium and CT
1-2 um wide
rich in glycoproteins
contains protein-polysaccharide complexes
what are the 2 layers of basement membrane seen microscopically?
lamina lucida- adjacent to basal cells
lamina densa- adjacent to connective tissue
what does the lamina densa project?
anchoring fibers project into connective tissue
what are hemidesmosomes?
dense plaques that attach epithelium to the basement membrane
what are desmosomes?
pairs of hemidesmosomes
how does stippling form?
in the boundary between oral epithelium and underlying connective tissue, connective tissue projects into epithelium connetic tissue papillea with epithelial ridges or rete pegs intervening. when rete pegs fuse- stippling
where are rete pegs missing from
junctional epithelium site
