Tooth development and anomalies of teeth (odontogenic tumors) Flashcards
Tissues of the tooth
dentin, enamel, cementum, pulp
periodontum structures
gingiva, PL, cementum, aveolar bone
stages of tooth development
initiation>bud>cap>bell>apposition>maturation
basic events of tooth developmental stages
Initiation: Cellular Induction
Bud Stage: Cellular Proliferation
Cap Stage: Proliferation, Differentiation
and Morphogenesis
Bell Stage: Proliferation, Differentiation
and Morphogenesis
Apposition: Induction and Proliferation, growth of mineralized tissues
Maturation: Maturation
ectoderm/mesenchyme (neural crest cells) interactions of tooth development, when?
Epithelium (ectoderm) plays an “instructional”role
during the pre-tooth bud stage of tooth formation.
At this early stage, the fate of the neural crest cells
(mesenchyme) has yet to be fully determined.
Epithelium specifies the “dental nature”of
the mesenchyme, and the mesenchyme, in turn,
specifies the tooth type (incisor vs. molar) and
nature of the product produced by the epithelium
(i.e., enamel matrix).
tooth development flow chart from the bilaminar germ disc
induction stage of tooth development, when?
structures involved?
weeks 6-7 ► Oral Ectoderm ► Neural Crest Cells ► Dental Lamina • Oral ectoderm (epithelium) invaginates into the mesenchyme, and is now called the dental lamina. • The lamina is separated from the surrounding mesenchyme by a basement membrane
bud stage
approx. 7th week
vestibule begins to form via apoptosis of mesenchymal cells, makes room for oral ectoderm invagination> dental lamina still forming (prolif of oral ectoderm)
early cap stage, time? what forms?
weeks 9-10
apoptosis will form the buccal vestibule
dental lamina forms outer dental/enamel epithelium and early stellate reticulum
cap stage, when? events? what is formed?
week 11
enamel organ formed from the dental lamina, opposite side the BM, the dental papilla begins to form but is undif at this stage.
enamel organ layers: outer/ inner enamel epithelium, and the stellate reticulum formed
dental follicle will begin to surround the entire structure
bell stage, weeks? what can be seen?
14-18 weeks
all layers of enamel organ can be seen: inner/outer epithelium, strantum intermedium, stellate reticulum
dental lamina, papilla and follicle all present
function of the external enamel epithelium, cell shape
protective barrier, cuboidal
function of internal enamel epithelium, cell shape
dif into ameloblasts, cuboidal
function of stellate reticulum, cell shape
supportive func in enamel production, star shaped cellular network in enamel organ
strantum intermedium function, cell shape
supportive of enamel production: produce alkaline phosphatase for mineralization, compressed cuboidal cells
dental sac function (what kind of fiber, gives rise to?)
collagen fibers around enamel organ, becomes PDL/cementum/bone
dental papilla, gives rise to?
cells nearest to IEE, spereated by BM, outer cells will dif into odontoblasts/. inner cells become pulp
cervical loop, site of what in adult?
Junction of the outer & inner enamel epithelia Site of cemento-enamel junction (CEJ) in the adult tooth (a.k.a., cervix)
hertwig’s epithelial root sheath, determines? when is it removed?
Fusion and apical extension of the outer and inner enamel epithelia. Determines the outline of the root dentin and the number of roots a tooth will have (epithelial diaphragm). It is removed before the cementum is laid down
modification to hertwig’s (normal development not mutation)
The epithelial
diaphragm is the modification of Hertwig’s Sheath creating “septa”
that divide the pupal tissue and create mutiple roots.
termination point of enamel formation, dentin growth pushes tooth?
Enamel formation stops at the termination of the enamel organ. Dentin
formation continues, and pushes the tooth occlusally.
root development completion time, events within root
Root length is not complete until 1 to 4 years after the tooth has emerged into the oral cavity.
The pulp chamber narrows, and the
apical opening constricts.
appostional growth
ameloblasts and odontoblasts interaction
cuboidal IEE cells grow to columnar and become ameloblasts with receptors to attract preodontoblasts (fibronectin)> line up opposite of one another> odonotblast dif> secrete mantle dentin> detected by ameloblasts, secrete enamel
as ameloblasts secrete enamel they grow away from the BM
odontoblast remain attached to the BM via processes as they secrete dentin, porcesses= dentin tubules, used to mineralize the predentin
mantle dentin, when? kinds of fibers? stimulates?
formed in appostional stage, first dentin formed
usually thin layer
collagen I and III perpindicular to DEJ
presence will stim ameolblasts to secrete enamel
migration of ameloblasts and odontoblasts paths
Migration of ameloblasts peripherally
Migration of odontoblasts inward (centrally)
active vs. non active ameloblasts
Actively secreting ameloblasts are tall columnar cells Inactive (a.k.a. reduced) ameloblasts are short columnar or elongated cuboidal cells
primary cuticle
At the final stage of mineralization, the reduced ameloblasts with the remaining cells of the outer enamel epithelium, stellate reticulum, and stratum intermedium form a membrane on the surface of the enamel. This is termed the primary cuticle (a.k.a. Nasmyth’s membrane).
anodontia
Refers to the total lack of tooth
development (no teeth)> due to dental lamina or enamel organ not forming, some cases of ectodermal dysplasia
hypodontia, most commonly affects which teeth?
Denotes the lack of development
of one or more teeth.
also due to dental lamina/enamel organ not forming
most commonly 3rd molar missing followed by max LI
oligodontia
Indicates the lack of formation of
six or more teeth (a subdivision
of hypodontia).
hyperdontia
The development of an increased number of teeth (the additional teeth are termed supernumerary). many possible kinds formation of additonal dental lamina/enamel organs
supernumerary teeth, originates at what stage?
Defect that
originates during the Initiation Stage that
results in the development of one or more extra
teeth (additional enamel organ/dental lamina).
mesodens, common?
The most common manifestation of
supernumerary tooth formation.
addtional tooth btwn the max CI
4th molars
possible supernumerary tooth form
odontoma, origin at what stage? kinds? treatment? can lead to?
originates during the Initiation Stage
and results in multiple small fragments of tooth
structure consisting of dentin, enamel,
cementum or any combination.
complex: do not resemble teeth
compound: resemble teeth
must be removed=they are invasive and can thin jaw bone leading to pathological fractures
complex odontoma
Comprised of a conglomerate
mass of enamel and dentin that bears no anatomic
resemblance to a tooth.
compound odontoma
Comprised of multiple,
small tooth-like structures.
abnormal root development cause
issues with epithelial diaphragm in hertwig’s root sheath> can lead to additional roots
taurodontism, cause?
An enlargement of the body and pulp
chamber of multirooted teeth with apical displacement
of the bifurcation, i.e., an exceptionally long root trunk
with very short roots.
caused by issue with Hertwig’s/epithelial diaphragms
dilacerations, cause?
defined as an abnormal angulation
or bend in the root.
due to hertiwgs/epthelail root sheath deviation
Lack of root formation?
possible, only enamel organ products produced
no hertwig’s root formation
IEE and OEE join at cerival loop and stop
shortened roots cause (not from development)
not always hertwigs but can also be cause by accelerated orthodontics causing root resorbtion
gemination, origin point?
Defect that originates during Cap
Stage of development that results in large single-
rooted tooth with one pulp cavity and exhibits
“twinning”in crown area.
tooth count is normal
fusion, origin point?
cap stage Refers to a double tooth in which the tooth count reveals a missing tooth when the double tooth is counted as one. tooth count will be one less
concresence, origin point? extraction complication?
Defect occurring during Apposition, hypercementosis
and Maturation stages that results in union of root
structure of two or more teeth by cementum
extraction leads to large perio defects
extra cusp formation, origin? what is defective?
Tubercle Formation: Defect occurring during Cap
Stage of development that results in an extra cusp
due to effects on enamel organ.
dentigerous cyst, origin point? incidence?
Originates by separation of the dental follicle (dental sac) from
the crown of an unerupted tooth but stays attached at CEJ. The cyst is attached at the CEJ. This cyst type comprises 20% of all jaw
cysts.
Keratocystic Odontogenic Tumor, origin, % of all odontogenic cysts , age range, common location, effect on bone, often present as, treatment/recurrence?
Arises from the cells rests of the dental lamina if stimed in right way (also called rests of Serres).
The OKC constitutes 3% to 11% of all odontogenic cysts.
60% of all cases are diagnosed in patients between the
ages of 10 and 40 yrs.
65% of all cases are located in the mandible.
OKCs are bone expanding cysts=invasive
OKCs located in the posterior mandible often present as
multilocular lesions.
Surgical removal is the treatment of choice. However,
there is a recurrence rate of approximately 30%.
common location of odontogenic keratocyst
most common in posterior mandible
odontogeinc cyst structure
Cyst wall consists of a 6-8 cell layer of stratified
squamous epithelium with parakeratosis (nuclei throughout the epithelial layer) at the luminal surface. The lumen is often filled with keratin.
The presence of inflammation will generally
cause epithelial proliferation and palisading of the
basal cell layer.
swirls of keratin present in the section
macro/microdontia, micro seen with? example?
enlarged teeth or small teeth
microdontia can be seen with cleft lips or palates, Ehler’s-Danlos, hypopititary, ectoderm disorders
Peg max LI
ameloblastoma, commonly found? epithelial components?
abnormal prolif of the enamel organ components, results in odontogenic tumor
commonly in mandible
mainly epithelial components resemble preameloblasts
multilocular
