Online Questions Flashcards
What stage of tooth formation involves the beginning of invagination of the developing tooth structure?
Cap stage
What is the bell-shaped structure that develops from the tooth bud?
Enamel organ
- It is ectodermal in origin
- Will be responsible for amelogenesis.
From what are odontoblasts derived?
Neural crest cells (Ectomesenchyme)
From where is differentiation of the odontoblasts controlled?
Inner enamel epithelium
- The differentiation of odontoblasts from undifferentiated ectomesenchymal cells is initiated and controlled by the ectodermal cells of the inner dental epithelium of the enamel organ.
From where does the signal initiating enamel formation originate?
Odontoblasts
- Once dentin formation has begun, the cells of the inner dental epithelium begin to respond to a signal from the odontoblasts and begin to deposit enamel.
When does the dental papilla become the dental pulp?
Late bell stage
- Odontoblasts begin to lay down dentin in the late bell stage. From this point on, the tissue within the invagination is known as the dental pulp.
What is the first thin layer of dentin that is formed?
Mantle dentin
- The first thin layer of dentin formed is called mantle dentin. The direction and size of the collagen fibers in mantle dentin differ from those in the subsequently formed circumpulpal dentin.
Epithelial cell rests of Malassez are remnants of what?
The Epithelial Rooth Sheath
- Epithelial cell rests of Malassez are cell remnants of the epithelial root sheath that persist in the periodontium in close proximity to the root after root development has been completed. They are normally functionless, but in the presence of inflammation, they can proliferate and under certain conditions may give rise to a radicular cyst.
Which cells secrete the hyaline layer of Hopewell-Smith?
Inner cells of Hertwig’s epithelial root sheath
- After the first dentin in the root has formed, the basement membrane beneath Hertwig’s sheath breaks up, and the innermost root sheath cells secrete a hyaline material over the newly formed dentin. After mineralization has occurred, this becomes the hyaline layer of Hopewell-Smith, which helps bind the soon to be formed cementum to dentin
What morphologic changes occur over time due to the dental pulp?
The overall size of the pulp chamber is reduced
The apical foramen is:
Variable in size and location
The apical constriction is:
The ideal end point of root canal cleansing
What does the dental pulp form as a defensive response?
Tertiary dentin
Approximately how many odontoblasts are present in the crown of a newly erupted tooth?
45,000 to 65,000/mm^2
- In the coronal part of the pulp space, the odontoblasts are numerous, relatively large, and columnar in shape
Which of the following cell types is an antigen-recognition cell in the dental pulp?
Odontoblasts
- Toll-like receptors (TLR2 and TLR4), when activated by components of gram-positive bacteria (lipoteichoic acid), cause the odontoblasts to release proinflammatory cytokines
What is the most prominent antigen-presenting cell in the dental pulp?
Dendritic cell
- These are antigen-presenting cells present most densely in the odontoblast layer and around blood vessels.
What type of collagen is most prominent in the dental pulp?
Type I
Which of the following is not a type of pulp stone?
- free
- attached
- embedded
- floating
Floating
What would be a typical level for interstitial pressure in a dental pulp?
+6 mmHg
What would be a typical level for interstitial pressure in an area of inflammation in a dental pulp?
+20 mmHg
Which type of nerves can be recruited to the pain system of the dental pulp in inflammation?
Aβ
- Their role in the pulp is uncertain, but it is now known from other tissues that in inflammation, these Aβ fibers can be recruited to the pain system.
What is a “pulp cap”?
Capping of exposed vital pulp tissue by placing a layer of mineral trioxide aggregate (MTA)
What is the effect on blood flow to the pulp when anesthetics with vasoconstrictors are used during restorative procedures?
It is reduced to less than half of its normal rate
- When most local anesthetics containing vasoconstrictors are used in restorative dentistry, the blood flow to the pulp is reduced to less than half of its normal rate. In the case of lidocaine with epinephrine, this effect is entirely due to the vasoconstrictor.
What is dentin “blushing”?
Vascular injury (hemorrhage) of pulp tissue, often during crown preparation - Thought to be due to frictional heat resulting in vascular injury (hemorrhage) in the pulp.
Why are deeper carious lesions more injurious to the dental pulp?
Increased dentin permeability in deeper areas and greater cellular injury to odontoblasts
- Dentin permeability increases exponentially with increasing cavity depth, as both the diameter and density of dentinal tubules increase with cavity depth (Fig. 2.5). Thus the deeper the cavity, the greater the tubular surface area into which potentially toxic substances can penetrate and diffuse to the pulp.
Why does a blast of compressed air directed at freshly exposed dentin create a sensation of pain?
It causes a rapid outward movement of fluid in patent dentinal tubules
What is the most important characteristic of any restorative material in determining its effect on the pulp tissue?
Ability to form a marginal seal
- That prevents the leakage of bacteria and their products onto dentin and then into the pulp.
What effect does orthodontic tooth movement have on the dental pulp?
It produces no clinically significant changes
What is the primary reason for placement of a liner between biocompatible restorative materials and the dentin?
To eliminate microleakage
Vital pulp therapies have variable rates of success. What is the most significant determinant of the success of vital pulp therapy?
Pulp status before the procedure