Embryology Definitions

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Name the 3 periods of pre-natal development.: Pre-implantation
Embryonic
Fetal
When does pre-implantation occur?: 1st week
When is the embryonic period and what happens?: 2nd week to the end of 8th week. Major development of body structure, cells change into tissues and organs (differentiate), and cells form systems (integrate)
What are the 3 embryonic layers and when are they formed?: Ectoderm
Mesoderm
Endoderm
Explain ectoderm: Outer layer that forms the brain, spinal cord, skin and appendages, enamel, and lining of oral cavity
Explain mesoderm.: Middle layer that forms bones, muscles, circ. system, kidneys, ducts, reproductive system, abdominal lining, dentin, pulp, cementum
Explain endoderm.: Inner layer that forms the digestive system lining, lining of lungs, parts of the urogenital system.
When does the 1st pair of brachial arches get formed?: week 4
What is the 1st brachial arch comprised of?: bones, muscles, nerves, lower lip, masticatory process, anterior of alveolar process
What is another name for the 2nd brachial arch?: Hyoid
What is the 2nd brachial arch, or hyoid, comprised of?: stapes of ear, styloid process (forms base of temporal), side and front of neck, muscles of facial expression (MOBZ)
The palate forms in 3 stages, what are they?: Primary palate
Secondary palate
Fusion
When is the hard and soft palate differentiated?: week 5 to 8 (primary dentin has begun, number of teeth, and arrangement)
When is the fetal period and what happens?: week 9 to 38. Systems continue growth, fetus is less vulnerable to malformation
What is odontogenesis?: The life cycle of a tooth.
What are the 3 stages of odontogenesis?: 1. Grow
2. Calcification
3. Eruption
Explain the bud stage of tooth growth.: -Tooth pattern is formed
-dental lamina makes curves in each arch for the buds of primary teeth
-by week 17 all 20 primary teeth are formed
Explain the cap stage of tooth growth.: Cells increase and grow to different steps and sizes depending on the tooth
Explain the bell stage of tooth growth.: Epithelial cells become ameoblasts
Peripheral cells become ________________.: odontoblasts
Inner cells of the dental sac become _______________.: cementoblasts
What is morphodifferentiation?: the process where the basic shape and size of each tooth is established.
What is calcification?: The hardening of material.
A _____ is the point where 2 developmental grooves cross over.: Pit
A _________ is the incomplete joining of the lobes during development.: Fissure
What is eruption?: The movement of teeth into the functional position in the oral cavity.
All teeth (primary and permanent) erupt, but only the primary teeth ___________.: Exfoliate
What teeth erupt at about 6 to 10 months?: Upper and lower centrals.
What teeth erupt at 7 to 10 months?: Lower laterals
What teeth erupt at 9 to 12 months?: Upper laterals
What teeth erupt at 12 to 18 months?: Upper and lower 1st molars.
What teeth erupt at 16 to 22 months?: Upper and lower canines.
What teeth erupt at 20 to 32 months?: Lower 2nd molars.
What teeth erupt at 24 to 32 months?: Upper 2nd molars.
What teeth exfoliate at 6 to 7 years?: Upper and lower centrals.
What teeth exfoliate at 7 to 8 years?: Upper and lower laterals.
What teeth exfoliate at 9 to 11 years?: Upper and lower 1st molars.
What teeth exfoliate at 9 to 12 years?: Lower canines.
What teeth exfoliate at 10 to 12 years?: Upper canines and upper and lower 2nd molars.
What teeth erupt at 6 to 7 years?: Upper and lower 1st molars and lower centrals.
What teeth erupt at 7 to 8 years?: Upper centrals and lower laterals.
What teeth erupt at 8 to 9 years?: Upper laterals.
What teeth erupt at 9 to 10 years?: Lower canines.
What teeth erupt at 10 to 12 years?: Upper and lower 1st and 2nd pre-molars.
What teeth erupts at 12 to 13 years?: Upper and lower 2nd molars and upper canines.
What teeth erupt at 17 to 21 years?: Upper and lower 3rd molars. (wisdom teeth)
What are succedaneous teeth?: Permanent teeth that replace the primary teeth.
What are the non-succedaneous teeth?: 1st, 2nd, and 3rd upper and lower molars.
What is micrognathia?: An abnormally small jaw. (usually results in a Class 2 occlusion)
What is macrognathia?: An abnormally large jaw. (usually results in a Class 3 occlusion)
What is microdontia?: Abnormally small teeth.
What is macrodontia?: Abnormally large teeth.
What are supernumary teeth?: Teeth in excess of 32.
What is dens in dente?: "Tooth within a tooth" (a cluster of enamel and dentin in the pulp)
What are pegged-shaped associated with?: Also known as Hutchinson's Incisors. Associated with maternal syphillis.
What is fusion?: When the dentin and enamel of one tooth are joined with 2 or more = reduced number of teeth in the arch.
What is gemination?: When a tooth bud tries to divide and when it fails, the result is an incisal notch.
What is amelogenesis imperfecta?: Defects in the enamel formation formation (hereditary)
Define hypocalcification.: Incomplete hardering of the enamel.
Define attrition.: The normal wearing away of tooth structure. The first sign of attrition is the wearing of mamelons.
Define abrasion.: Abnormal wearing of teeth.
Define impaction.: Tooth remains unerupted.
Causes:
-premature loss of baby teeth
-developing tooth shifts horizontally
-teeth shifts because of other tooth in space or lack of jaw space or large crowns.
Define bruxism.: Involuntary grinding or clenching of teeth.
What is erosion?: Wearing of lingual surfaces caused from stomach acids; usually seen in those with bulimia.
What can various head/neck infections be caused by?: Orofacial piercings.
Define exostoses.: Also known as tori or torus.
In plate - torus palatinus
Lower lingual - torus mandibularis (near the premolar/molar area)
Both are benign bony overgrowths.
Describe cleft lip.: When the maxillary and medial nasal processes do not fuse.
Describe cleft palate.: When the palatal shelves do not fuse with the primary plate (incisive papilla area)
Describe cleft uvula.: Covered with mucous membrane and looks like a bony projection in the center or middle of the hard palate.
Define ankylglossia.: "tongue-tie" A short lingual frenum is extended to the tip (apex) of the tongue.
Define glossitis.: General term for inflammation of the tongue.
Describe pernicious anemia.: The body is not able to absorb vitamin B12 (ie seafood, meats, milk)
S&S: anemia, pallor, fatigue, nausea, diahhrea, abdominal pain, loss of appetite.
Define fissured tongue.: Tongue appears to have deep grooves on dorsum. May be caused from vitamin deficiency or chronic trauma.
What is a geographic tongue?: Loss of filiform papillae. Results in smooth patches. More common in women.
Define black hairy tongue.: After antibiotics, papillae are elongated (due to oral flora imbalance)and become stained with food, tobacco, etc.
What is atrophic candidias?: After broad spectrum of antibiotics, mouth feels like its been burned; antifungal therapy should clear it in 14 days.
Define candidias (of soft tissue): Most common oral-fungal infection. Initial clinical manifestation in pts with AIDS.
What is morphology?: The study of the shape and form of teeth.
Which tooth has the longest root?: Cuspids (also known as canines)
Name the 5 tooth surfaces.: Occlusal (incisal)vestibular, labial, facial), lingual, mesial, distal
Where is the greater palatine foramen?: On either side of the soft palate.
Where is the incisive foramen?: Under the incisive papilla.
What is histology?: The study of the structure and function of the teeth and oral tissue.
Describe the crown of the tooth.: Dentin and pulp covered by enamel.
Describe the root.: Has dentin and pulp covered by cementum.
What is the anatomic crown?: Part of the tooth that is covered by enamel.
What is the clinical crown?: Part of the tooth that is visible.
The root is usually embedded in the _________ ___________.: alveolar process
What is bifurcation and trifurcation?: Bifurcation is the division into 2 roots. Trifurcation is the division into 3 roots.
Define apex.: The tapered end of each root.
Where is the apical foramen?: At the opening of each root apex.
Define the periapical area.: Consists of anything surrounding the apex.
Name the tissues of the tooth.: Enamel, dentin, pulp, cementum
Describe enamel.: -makes up the anatomic crown
-hardest material in the body
-crushing strength of 100,000 psi.
-formed by ameloblasts
-96-99% inorganic, 1-4% organic
-composed of prisms (enamel rods)
Describe dentin.: -makes up bulk of tooth
-covered by enamel on the crown and cementum on the root.
-supports the enamel
-formed by odontoblasts
-contain dental tubules
-capable of continued growth and repair
What are the types of dentin?: Primary-formed before eruption
Secondary-formed after eruption and continues slowly
Tertiary-reparative, formed in response to irritation
Describe pulp.: -inner portion of the tooth pulp chamber
Define coronal pulp.: Pulp that is in the crown.
Define radicular pulp.: Pulp in the root portion. Made up of nerves and blood vessels.
What are fibroblasts?: Cells that form the pulpal tissue
Describe cementum.: -rigid (bone-like) connective tissue
-covers the root
-NOT shiny
-formed by cementoblasts
What is the difference between osteoclasts and osteoblasts?: Clasts resorb bone and blasts build bone.
What is the periodontium divided into?: Attached apparatus (cementum, alveolar process, and periodontal ligaments)
Gingival unit (lining mucosa, masticatory mucosa, and specialized mucosa)

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