Ten cates oral histology ed 8th and some Flashcards
3 most common types of apatite crystal in enamel:
carbonated hydroxyapatite (CAP) hydroxyapatite (HAP)
fluorohydroxyapatite (FHAP)
what is the radiological density of dentin, enamel and cementum
The radiological density of cementum is approximately 1200 - 1500 Hounsfield “units” (H).
density of dentin is 1600 - 1800 H.
Enamel is 96 – 98 % inorganic material, with a density of 2400 - 2600 H
How many dentin tubules are there per root
There are 30,000-75,000 dentin tubules/mm2 root
Lingual tumors are an uncommon occurrence in the dog, accounting for only ?% of oral tumors.
Lingual tumors are an uncommon occurrence in the dog, accounting for only 2-4% of oral tumors.
of lingual tumors, malignant tumors comprised ?% of reported neoplasms with ? and ? being the most frequent.
of lingual tumors, malignant tumors comprised 64% of reported neoplasms with malignant melanoma and squamous cell carcinoma being the most frequent.
Dental fractures in domestic dogs are common. The prevalence is reported to be as high as ?%.
Dental fractures in domestic dogs are common. The prevalence is reported to be as high as 27%.
When does bone lysis between radiographically evident
Bone lysis becomes radiographically evident when
more than 40 % of the compact bone has been already demineralized;
Acellular cementum is derived from what component of the tooth germ
Dental follicle also called dental sac
What is passive eruption
Passive eruption refers to the uncovering of the anatomic crown because of apical recession of the surrounding tissues (junctional epithelium and alveolar bone), rather than bodily movement.
Who classified the stages of passive eruption
Gottlieb and Orban
Who many stages are there of passive tooth eruption
4
How many types of altered passive eruptions are there
Type Ia, Type Ib, Type 2a, Type 2b (Coslet)
What tooth germ layer does the Junctional epithelium come from
The reduced outer enamel epithelium layer from the enamel/dental organ of the ectoderm.
Who developed the Periodontal Index (PI)
Russell
Who developed the Periodontal Disease Index (PDI)
Ramfjord
Tooth eruption is the result of what two types of eruption
Active and passive eruption.
Name the three zones of the caries lesion
1) translucent zone (demineralisation zone)
2) Dark zone (mixed de/re-mineralization zone)
3) body of the lesion zone
Name the four types of nerve endings to the TMJ
1) Ruffini’s corpuscles (to the capsule, Proprioceptin)
2) Pacini’s corpuscles (to the capsule, mechanoreception)
3) Golgi tendon organ
4) Free nerve endings (most abundant, nociception)
name the major immunoglobulin of saliva
ImmunoglobulinIgA
name the two main secretory cells of the saliva glands
- Mucous
2. Serous
What does serous saliva glands produce
- proteins
2. glycoproteins
is saliva hypotonic, isotonic or hypertonic?j
Hypotonic
Name the principal cells of the PDL
Fibroblast
Name the nerve supply to the salivary glands
They are innervated by postganglionic nerve fiber of the sympathetic and parasympathetic autonomic nervous system
name the parasympathetic cranial nerves that innervate the salivary glands
Via the superior or inferior salivary nuclei in the brainstem via CN VII (facial) through the lingual nerve - submandibular gland
-“- CN IX (glossopharyngeal) through the auriculotemporal nerve - Parotid
Descrbe the path of the sympathetic nerves that innervate the salivary glands
preganglionic symphatetic nerve via Thoracic spinal cord to the postganglionic neurons in th superior cervical ganglion - with the arterial blood supply to the gland
Name the non-principal cells of the PDL
1) Epithelial cells (remnants of HERS) - known as epithelial cell rests of Malassez
2) Undifferentiated mesenchymal cells
3) Stem cells (differentiate into adipogenic, cementogenic, osteogenic and chrondrogenic cells)
Name the fiber groups of the PDL
1) Alveolar crest
2) horizontal
3) oblique (most abundant)
4) Apical
5) interradicular
Name the three types of elastic fibers in the periodontium
Elastin
Oxytalan (only one found within the PDL)
Elaunin (found within the fibers of the gingival ligaments .
Name the different tooth movements, during eruption
1) Preeruptive movement
2) Eruptive movement
3) Posteruptive
What is the gubernacular cord?
It is the fibrocellular follicle surrounding a successional tooth, that retains its connection with the mucosal membrane by means of a strand of fibrous tissue containing remnants of the dental lamina
what are the gubernaculum canals?
Are canals were the gubernaculum cords use to sit in the bone. They delineate the eruptive pathways for the permanent teeth.
what is released just prior to eruption of a tooth that cause the redness of the gum
Enamel matrix proteins are released just prior to and during
mucosal penetration, resulting in a local hypersensitivity
reaction and clinical signs including erythema
Name the theories of the eruption mechanism
1) Root elongation
2) Alveolar bone remodeling
3) PDL force formation
4) Dental follicle force (hydrostatic force)
5) Gubernaculum contraction
name the 3 phase of tooth eruption
pre-eruptive phase where
the dental germ moves
pre-functional phase once the crown
has formed and root formation begins. intraosseus and
a supraossesus phase.
functional phase
that begins once the tooth comes into occlusion,
Are there any changes in the cementum at orthodontic tooth movement?
no - theoretically, but some damage will likely happen due to the forces applied.
Describe the orthodontic tooth movement over time
1) Initial compression phase
2) Hyalinization phase (10-20 days) - ligaments that undergo this process (Lag phase)
3) further tooth movement (Postlag phase
what is the Nasmyth membrane
During enamel
production, the enamel organ is compressed and the ameloblasts
form a protective layer known as the primary enamel cuticle , or
Nasmyth’s membrane . The primary enamel cuticle (also known as
reduced enamel epithelium) acts as a protective layer for erupting
When does clinical demonstrable resorption of teeth occur with orthodontic movement?
Only after application of heavy forces and the movement of teeth for more than 30 days.
Types of Cementum
- Acellular cementum - contains no cementocyte within the mineralized tissue. Covers the cervical 1/3-1/2 of the tooth
- Cellular cementum - contains cementocytes within its mineralized tissue. Covers the apical half of the root.
Salivary Ductal System consists of?
- smallest ducts in contact with acini, larger as they empty into collcting duct until oral cavity
- has secretory portion within acinar cells, and excretory portion in connective tissue
- secretory portion substances enter and leave by ion exchange with blood vessels, excretory is just a saliva collecting tubule
- acinar cells drain directly into intercalated ducts that open into striated ducts (both intralobular), then into interlobluar ducts
What are the 5 major proteins of enamel?
- Amelogenin
- Ameloblastin
- Enamelin
- Kallikrin 4
- Mmp-20
Major matrix protein of Enamel
Amelogenin (several isoforms)
Major matrix protein of Dentin
Collagen (type 1)
Noncollagenous matrix proteins of dentin are?
- Dentin sialophosphoprotein
- Dentin glycoprotein
- Dentin phosphoprotein
- Dentin sialoprotein
- Dentin Matrix protein 1
- Bone sialoprotein
- Osteopontin
- Osteocalcin
- Osteonectin
Nonamelogenins matrix proteins in enamel are?
- Ameloblastin
- Enamelin
- Sulfated protein
Inheritance of Dentinogenesis imperfecta
results from an inherited structural deficiency in collagen formation
- Since dentin and bone is supported by a collagen framework, dentin affected by this disease is structurally defective
- Several types of the condition are recognized, most are Type II . while Type I is coupled with osteogenesis imperfecta
This cartilage is in the first branchial arch.
Meckel’s cartilage
2nd branchial arch -Cartilage
Reichert’s cartilage:
- Stapes
- Styloid process
- Stylohyoid ligament
- lesser horn hyloid
Innervation and vascularization of Pharyngeal Arches
- First arch: Trigeminal nerve V
- Second arch: Facial nerve VII
- Third arch: Glossopharyngeal IX
- Fourth arch: Vagus X
secondary palate formation
- Nasal septum growns downward form the frontonasal process.
- the bilateral maxillary processes give rise to two palatal shelves (lateral palatine processes). Grow inferiorly and deep on the inside of the stomodeum in a vertical direction along side of the developing tongue. The tongue is forming at the same time.
- Shelf-elevating forces the the palatal shelves to flip superior within a few hours.
- The palatal shelves elongate and move medially toward each other to form the secondary palate.
- Will give rise to the posterior two thirds of the hard palate and contain the maxillary canines and posterior teeth, the uvula, and soft palate, the median palatine raphe, and under the median palatine suture on the adult bone.
Describe the formation of the tongue
First pharyngeal arch develops tuberculum impar protuberance.
Two lateral lingual swellings develop, fuse at median sulcus-> Anterior 2/3 of tongue
Large midline swelling (copula) develops from the 2nd, 3rd and 4th arches give hypobranchial eminence, which develops into posterior 1/3
Centers of ossification in mandible. How many?
two- anteriorly separated by the symphysis - that grow backwards
Secondary (Growth) Cartilages in Mandible are?
- occupies most of ramus, quickly ossified
- thin remnant remains into teens, important for mandible growth
1) Condylar Cartilage: ossification center for ramus - endochondral ossification
2) Coronoid Cartilage: appears at 4 months then disappears immediately
3) Symphysial Cartilage: develops at ends of Meckel’s cartilage
Development of maxilla is it similar to the mandible?
There are no arch cartilage or primary cartilage but the center of ossification is closely associated with the cartilage of the 1) nasal capsule and the 2) zygomatic or malar cartilage
Name the three structural elements of the cytoskeleton
- microtubules (25 nm in dia)
- microfilaments (6-8nm in dia.)
-intermediate filaments (10 nm in dia)
What is the primary epithelial band?
A continuous horseshoe-band of thickened epithelium in the location of upper and lower jaws
The primary epithelial band divides into
Dental lamina
Vestibular lamina
dental placodes
mark the sites of tooth development
Three stages of tooth development are?
Bud
Cap
Bell
what controls the position and number of tooth germs along the oral surface?
- signals appear to originate from oral epithelium
- Fgf-8 plays role in oral-aboral axis and seems to play role in determining positions where tooth germs will form
- Pax-9 gene (one of earliest mesenchymal genes) - define localization of tooth germs
- Pax-9 is induced by Fgf-8 and is repressed by bone morphogenic proteins (BMP-2 and 4).
- Fgf-8, BMP-2 and 4, expressed in non overlapping areas (Pax=9 expressed at sites where Fgf-8 is but not Bmp)
- Shh also implicated in tooth initiation
Name and describe 2 hypothetical models proposed to explain how different tooth shapes developed
- field model - proposes that factors responsible for tooth shape reside within ectomesenchyme in distinct graded and overlapping fields for each tooth family
- clone model - proposes each tooth class is derived from a clone of ectomesenchymal cells programmed by epithelium to produce teeth of given pattern
Describe the first stage of tooth development
Bud stage: First epithelial incursion into the ectomesenchyme of the jaw. The epithelial bud continues to proliferate into the ectomesenchyme, cellular density increases. The process is referred to as the <i>Condensation </i>of the ectomesenchyme
- What does the transition from bud to cap mark?
- Onset of morphologic differences between tooth germs that give rise to different types of teeth.
- Msx-1 is expressed with Bmp-4 in mesenchymal cells that condense around tooth buds
- Multiple other factors and gene are expressed, such as Pax-9, Activin-betaA
What happens during the cap stage of tooth development?
Formation of tooth germ as <i>enamel organ</i> forms into a cap shape that surrounds inside mass of <i>dental papilla </i>(ball of condos ectomesenchymal cells), with an outside mass of <i>dental follicle (sac)</i> <i>Proliferation</i>, differentiation and morphogenisis
Dental Papilla?
- Arises from ectomesenchyme
- a condensed zone of cells beneath the enamel organ, separated by basement membrane
- it will from dentin and pulp
dental follicle?
less condensed than dental papilla
-surrounding ectomesenchymal cells give rise to cememntum and periodontal ligament
Dental Organ?
aka “Tooth Germ”
- Enamel Organ
- Dental Papilla
- Dental Follicle