PEDO pt 1 Flashcards
initiation (bud stage) of primary teeth occurs in week ___ of embryonic life
6
which teeth arise from the dental lamina? where do the other teeth arise from?
- all primary teeth and permanent molars
- all permanent incisors, canines, and premolars arise from their primary predecessor
failure of what stage of development results in congenitally missing teeth?
- initiation (bud stage)
- alternatively, excessive budding results in supernumerary teeth
what are the stages, in order, of tooth development?
- initiation (bud stage)
- proliferation (cap stage)
- histodifferentiation and morphodifferentiation (bell stage)
- apposition
- calcification
during the proliferation (cap) stage, peripheral cells of the cap form the ___ and ___
inner and outer enamel epithlium
failure in the proliferation results in ___
congenitally missing teeth
excessive proliferation results in ___
a cyst, odontoma, or supernumerary tooth, depending on the amount of cell differentiation
during the histodifferentiation and morphodifferentiation (bell) stage, cells of the dental papilla differentiate into ___, and cells of the inner enamel epithelium differentiate into ___
- odontoblasts
- ameloblasts
failure in histodifferentiation results in ___, and failure in morphodifferentiation results in ___
- structural abnormalities of the enamel and dentin (amelogenesis imperfecta, dentinogenesis imperfecta)
- size and shape abnormalities, such as peg lateral incisors and macrodontia
what happens during the apposition stage?
ameloblasts and odontoblasts deposit a layerlike matrix
disturbances in apposition result in ___
- incomplete tissue formation
- for example, an intrusive injury to a primary incisor may disrupt enamel apposition and result in an area of enamel hypoplasia
enamel is composed of ___% inorganic material and ___% organic material and water
96%, 4%
where does calcification begin?
begins at cusp tips and incisal edges and proceeds cervically
what can cause hypocalcification?
localized infection, trauma, and excessive systemic fluoride ingestion
what are the approximate calcification times for primary teeth?
- central incisor 14 weeks in utero
- first molar 15 weeks in utero
- lateral incisor 16 weeks in utero
- canine 17 weeks in utero
- second molar 18 weeks in utero
what are the approximate maxillary eruption times for primary teeth?
- central incisor 10 months
- lateral incisor 11 months
- first molar 16 months
- canine 19 months
- second molar 29 months
- a 6 month variation in eruption time is considered normal
what are the approximate mandibular eruption times for primary teeth?
- central incisor 8 months
- lateral incisor 13 months
- first molar 16 months
- canine 20 months
- second molar 27 months
- a 6 month variation in eruption time is considered normal
what are the approximate calcification times for permanent maxillary teeth (excluding 3rd molars)?
- first molar birth
- central incisor 3-4 months
- canine 4-5 months
- lateral incisor 10-12 months
- first premolar 1.5 years
- second premolar 2 years
- second molar 2.5 years
what are the approximate calcification times for permanent mandibular teeth (excluding 3rd molars)?
- first molar birth
- central incisor 3-4 months
- lateral incisor 3-4 months
- canine 4-5 months
- first premolar 1.75 years
- second premolar 2.25 years
- second molar 2.75 years
what are the average eruption times for maxillary permanent teeth?
phone number: 781-0062
what are the average eruption times for mandibular permanent teeth?
phone number: 679-0161
eruption of a tooth begins when the crown has completed ___
calcification
typically, it takes ___ years for most crowns to complete formation except for first molars and cuspids, which take how long?
- 4-5 years
- first molars take 3 years
- cuspids take 6 years
it takes approximately ___ years from start of calcification to root completion, except for canines, which take how long?
- 10 years
- canines take 13 years
teeth typically erupt through the bone with how much root formation? they typically erupt through gingiva with how much root formation
- 2/3 root formation for bone
- 3/4 root formation for gingiva
the interval between crown calcification and full interdigitation is about ___ years
5
eruption to root completion takes approximately ___ years
3
what are the most common eruption sequences for maxillary and mandibular teeth?
- maxilla: first molar, central, lateral, first premolar, second premolar, canine, second molar
- mandible: first molar, central, lateral, canine, first premolar, second premolar, second molar
supernumerary teeth affect which gender more, and what percent of the population is affected?
- M:F 2:1
- 3%
what are the most common supernumerary teeth?
mesiodens, most of which are palatal
what are the two classifications of supernumerary teeth?
- supplemental (has typical anatomy)
- rudimentary (conical, tuberculate, or molar-shaped)
excluding 3rd molars, what is the incidence of hypodontia (congenital absence)?
1.5-10%
what are the most common congenitally missing teeth in order, excluding 3rd molars?
- mandibular second premolar
- lateral incisor
- maxillary second premolar
microdontia is seen in what developmental defects?
- ectodermal dysplasia
- chondroectodermal dysplasia
- hemifacial microsomia
- down syndrome
- another example of microdontia is a peg lateral
macrodontia is seen in what developmental defects?
facial hemihypertrophy and otodental syndrome
___ is the union of two primary or permanent teeth (which is it more common in?)
fusion, more common in primary teeth, almost always in anterior teeth
describe the pulp chambers/canals of fused teeth
they have two pulp chambers and two pulp canals
between tooth fusion and tooth gemination, which one has a normal number of teeth, and which has one less than normal?
- gemination has a normal amount
- fusion has one less
___ is the division of a single tooth bud, resulting in a bifid crown, and is more common in ___ teeth
- gemination (have a single pulp chamber)
- primary
___ is an anomaly of tooth shape and results in an extra cusp
- dens evaginatus
- aka talon cusps in incisors
why should care be taken with any operative procedure on a tooth with dens evaginatus?
the anomaly has enamel, dentin, and pulp
dens invaginatus (also called ___) is caused by ___ and has been termed “tooth within a tooth”
- dens in dente
- invagination of the inner enamel epithelium
dens invaginatus most commonly occurs in what teeth?
permanent maxillary lateral incisors
what is the ideal treatment for dens invaginatus?
preventive treatment; small restoration or sealant
___ is characterized by vertically long pulp chambers and short roots
taurodontism
when is taurodontism clinically significant?
if pulp therapy is required or during the exfolation process
a dilacerated tooth usually occurs as the result of ___
- an intrusive or displacement injury to a primary incisor
- it is also a consistent finding in congenital ichthyosis
enamel hypoplasia may be due to what two main factors?
environmental or genetic
what are the environmental factors that may be responsible for enamel hypoplasia?
- systemic diseases, especially fevers
- fluorosis
- nutritional deficiencies, especially vitamins A, C, D, calcium and phosphorus
- neurologic defects (sturge-weber syndrome and cerebral palsy)
- cleft lip and palate, radiotherapy and chemo, nephrotic syndrome, lead poisoning, rubella embryopathy
- local infection, trauma
what are the genetic factors that may contribute to enamel hypoplasia?
amelogenesis imperfecta
___ refers to quantity deficiencies of enamel, whereas ___ refers to quality deficiencies of enamel
- hypoplasia
- hypocalcification
what are the environmental and genetic factors that contribute to enamel hypocalcification?
- environmental are the same as for hypoplasia
- genetic amelogenesis imperfecta, hypocalcified type (normal thickness of enamel but is poorly calcified and fractures easily)
what is the incidence of amelogenesis imperfecta?
1/14,000
amelogenesis imperfecta is related to the enamel only and is dependent on ___
the developmental stage of enamel
what is the pulp and root morphology in amelogenesis imperfecta?
normal