Enamel Dentin Pulp Flashcards
What type of material is mature enamel?
Mature enamel is a crystalline material and the hardest mineralized tissue in the human body.
What is notable about enamel in its mature state?
It is noted for its almost total absence of softer organic matrix.
How can healthy enamel be removed?
It can only be removed by rotary cutting instruments or rough files.
What is one of the primary goals of dental professionals?
Preservation of the enamel is one of their primary goals.
Is enamel a renewable tissue?
No, enamel is not a renewable tissue.
What is the vascular nature of enamel?
Enamel is avascular.
Does enamel have a nerve supply?
No, enamel does not have a nerve supply.
Can enamel regenerate?
No, enamel is not a renewable tissue.
Is enamel a static tissue?
No, enamel is not static and can undergo mineralization changes.
What is the composition of mature enamel?
Mature enamel is composed of 96% inorganic material, 1% organic material, and 3% water.
What is the main crystalline component of enamel?
The main crystalline component is calcium hydroxyapatite, with the chemical formula Ca₁₀(PO₄)₆(OH)₂.
How does enamel appear on radiographs?
Enamel appears more radiopaque than dentin, pulp, and surrounding periodontium.
What part of the tooth is typically visible in a healthy mouth?
Enamel is typically the only visible part of a tooth.
What does enamel cover?
Enamel covers the anatomic crown.
Where is enamel thinner and thicker?
Enamel is thinner in the cervical region and thicker on chewing surfaces.
What aesthetic property does enamel provide?
Enamel gives teeth their esthetic white color.
How does enamel on primary teeth differ from enamel on permanent teeth?
Enamel on primary teeth is more opaque and appears whiter than on permanent teeth.
What happens to permanent molars over time in terms of wear?
The permanent first molars wear more than the second molars, and the second molars wear more than the third molars.
What is the wear rate of enamel from normal factors?
The wear rate of enamel is approximately 8 micrometers per year from normal factors.
How can habits like bruxism affect tooth enamel?
Habits like bruxism (grinding) can remove larger amounts of tooth material.
What is a wear facet?
A wear facet is a flat, polished area, usually found on the occlusal or incisal surfaces of the teeth.
How is a wear facet created?
It is created by repeated contact and friction between opposing teeth during chewing or parafunctional habits like grinding (bruxism).
What is abrasion?
Abrasion is the loss of enamel caused by friction, such as from excessive toothbrushing or abrasive toothpaste.
What is erosion?
Erosion is the process by which acids dissolve the hard tissues of teeth, leading to tooth structure loss.
In which patients is erosion particularly apparent?
Erosion is particularly apparent in patients with the eating disorder bulimia.
What other conditions can cause erosion?
Erosion can also occur due to acid reflux or hyperemesis during pregnancy.
What is ‘Meth Mouth’?
‘Meth Mouth’ is an informal name for advanced tooth decay attributed to heavy methamphetamine use.
Is methamphetamine directly acidic or corrosive to teeth?
No, methamphetamine is not directly acidic or corrosive, nor is contamination from its manufacture the primary cause of ‘Meth Mouth’.
Can ‘Meth Mouth’ occur in users of pharmaceutical-grade methamphetamine?
Yes, it has been observed in people who abuse pharmaceutical-grade methamphetamine as well.
What causes ‘Meth Mouth’ according to the American Dental Association?
It is likely caused by a combination of drug-induced psychological and physiological changes leading to hyposalivation and xerostomia (dry mouth).
What other factors contribute to ‘Meth Mouth’?
Extended periods of poor oral hygiene, frequent consumption of high-calorie carbonated beverages or sugary foods, and teeth clenching and grinding (bruxism) contribute to ‘Meth Mouth’.
What do caries do to enamel and other hard tooth tissue?
Enamel and other hard tooth tissue can be lost due to caries.
What is another name for caries?
Caries is also known as decay or cavities.
How are caries formed?
Caries is a process in which a cavity is created by demineralization or the loss of minerals.
What type of disease is caries?
Caries is a chronic infectious disease caused by bacteria in the mouth producing acid that dissolves enamel.
How does bacteria in the mouth contribute to caries?
Bacteria feed on sugars and refined carbohydrates, producing acid that attacks enamel.
What role does saliva play in the prevention of caries?
Saliva helps repair enamel, but if it cannot keep up with the acid production, bacteria can penetrate the tooth and cause a cavity.
What are risk factors for caries?
Risk factors include a diet high in sugars, poor oral hygiene, reduced salivary flow, and being a child or older adult.
What is a white spot lesion?
A white spot lesion is an early sign of decay where minerals have been lost from the enamel.
What can untreated tooth decay lead to?
Untreated tooth decay can cause pain, infection, and tooth loss.
What is a non-cavitated lesion?
A non-cavitated lesion refers to initial caries lesion development before cavitation occurs.
How can a balance between demineralization and remineralization impact caries?
Reestablishing this balance may stop the caries process but may leave a visible sign of past disease.
How are non-cavitated lesions characterized?
They are characterized by changes in color, glossiness, or surface structure due to demineralization before there is a macroscopic breakdown in the tooth’s surface.
What do carious lesions represent?
Carious lesions represent areas with net mineral loss caused by an imbalance between demineralization and remineralization.
What is remineralization?
Remineralization is the deposition of minerals into mature enamel from salivary minerals, fluoride, or other therapies.
How can the caries disease process be stopped?
Reestablishing a balance between demineralization and remineralization may stop the caries disease process.
Can remineralization leave visible signs of past disease?
Yes, remineralization may still leave a visible clinical sign of past disease.
What is abfraction?
Abfraction is the loss of enamel thought to be caused by tensile and compressive forces during tooth flexure.
When does abfraction likely occur?
It possibly occurs during parafunctional habits with occlusal loading.
What happens to the enamel during abfraction?
The enamel ‘pops off’ from the dentin layers, starting at the cervical region.
What risks are associated with lesions caused by abfraction?
These lesions may lead to further wear, dentinal hypersensitivity, or caries.
What is the process of enamel matrix formation called?
The process is called amelogenesis.
During which stage of tooth development does enamel matrix formation occur?
It occurs during the apposition stage of tooth development.
Which cells produce the enamel matrix?
The enamel matrix is produced by ameloblasts during their secretory phase.
What is the approximate size of ameloblasts?
Ameloblasts are approximately 4 micrometers in diameter and 40 micrometers in length.
How is enamel matrix secreted by ameloblasts?
Each ameloblast secretes enamel matrix from its Tomes process, a projection at the basal end facing the dentinoenamel junction (DEJ).
How much enamel matrix do ameloblasts produce daily?
Ameloblasts produce approximately 4 micrometers of enamel matrix daily.
What is the mineralization level of the initial enamel matrix?
The initial enamel matrix is approximately 30% mineralized.
What are the components of the initial enamel matrix?
The enamel matrix is composed of proteins, carbohydrates, and a small amount of calcium hydroxyapatite crystals.
Where does enamel matrix formation begin?
It begins in the incisal or occlusal part of the future crown near the DEJ.
What is the ‘first wave’ of enamel appositional growth?
The first wave occurs on the masticatory surface, later extending to the non-masticatory surface.
What is the ‘second wave’ of enamel appositional growth?
It overlaps the first wave and moves cervically toward the cementoenamel junction (CEJ).
What is the initial mineralization level of the enamel matrix?
The initial enamel matrix is approximately 30% mineralized.
What is the enamel matrix composed of?
The enamel matrix is composed of proteins, carbohydrates, and a small amount of calcium hydroxyapatite crystals.
Where is the enamel matrix first formed?
The enamel matrix is first formed in the incisal or occlusal part of the future crown, nearer to the forming dentinoenamel junction (DEJ).
What is the ‘first wave’ of enamel appositional growth?
The ‘first wave’ occurs on the masticatory surface, which later moves to the non-masticatory surface.
What is the ‘second wave’ of enamel appositional growth?
The ‘second wave’ overlaps the first wave, with the entire process moving cervically to the cementoenamel junction (CEJ).
What happens during the maturation process of enamel matrix?
The enamel matrix progresses from less mineralized to more mineralized, achieving its final structure.
During which stage of tooth development does the enamel matrix complete its mineralization?
The enamel matrix completes its mineralization during the maturation stage of tooth development.
To what level does the enamel matrix mineralize during maturation?
The enamel matrix mineralizes to its full level of 96%.
What stages of tooth development are involved in the mineralization of the enamel matrix?
The mineralization of the enamel matrix involves two stages: the apposition stage and the maturation stage.
Does enamel mineralization continue after the tooth erupts?
Yes, enamel mineralization continues after the eruption of the tooth.
What is posteruptive maturation?
Posteruptive maturation is the deposition of minerals, such as fluoride and calcium, from saliva into hypomineralized areas of enamel.
How can fluoride enter the enamel systemically?
Fluoride can enter the enamel systemically through the blood supply of developing teeth by ingestion of fluoride in drops, tablets, or treated water.
What are preeruptive methods of fluoride delivery?
Preeruptive methods involve systemic intake of fluoride, where fluoride ions are incorporated into the hydroxyapatite (HAp) structure by substituting for hydroxide or carbonate ions, creating fluoride-enriched HAp.
How can fluoride enter the enamel topically?
Fluoride can enter the enamel topically through direct contact with exposed tooth surfaces, such as with professional applications or over-the-counter products like rinses, gels, foams, chewable tablets, and fluoridated toothpaste.
What are posteruptive methods of fluoride delivery?
Posteruptive methods involve topical applications that strengthen enamel after the teeth have erupted.
Which type of fluoride use is more important in caries prevention, topical or systemic?
Topical fluoride use has a more important role in caries prevention than systemic use.
How does topical fluoride help prevent caries?
Topical fluoride increases remineralization of demineralized enamel regions, restores enamel with minerals, and inhibits microbial acid production, reducing potential enamel destruction.
What is remineralization in the context of fluoride?
Remineralization is the deposition of minerals into enamel in a way that resembles the original enamel structure, with larger and more acid-resistant crystals being deposited.
How does fluoride reduce enamel destruction?
Fluoride interferes with the microbial acid production of bacteria, reducing the potential for enamel destruction.
How is fluoride exposure reinforced for all age groups?
Fluoride exposure is reinforced through a combination of fluoride therapies, including both systemic and topical methods.
What is Silver Diamine Fluoride (SDF) used for?
SDF is used to arrest and prevent dental caries and relieve dentinal hypersensitivity.
In which cases is SDF particularly useful?
SDF is useful for cases of chronic severe xerostomia, multiple carious lesions, behavioral management patients, and anatomic niches (e.g., furcations, restoration margins, and partially erupted molars).
What is a notable effect of SDF on oxidizable surfaces?
SDF will stain most oxidizable surfaces, such as demineralized dentin and enamel, black.
Why might esthetics not be a primary concern when using SDF?
Esthetics are not the main concern in high-risk caries cases where SDF is typically used.
What further discussion is planned for SDF?
SDF will be discussed more in the Dental Materials course during the summer.
What is the purpose of enamel sealants?
Enamel sealants protect against enamel caries by covering the deepened pit and groove patterns on teeth.
Can sealants be placed on non-cavitated lesions?
Yes, sealants may be placed on non-cavitated (incipient) lesions to arrest caries.
When should sealants be applied to teeth?
Sealants should be applied as soon as these teeth appear in the mouth, before they have a chance to decay.
How do sealants stop decay when placed on top of incipient caries?
Sealants stop decay by sealing off the supply of nutrients that cavity-causing bacteria need.
Where will sealants be discussed in greater detail?
Sealants will be discussed in greater detail in the Dental Materials course this summer.
What is the crystalline structural unit (not the compound) of enamel called?
It is called the enamel rod or enamel prism.
How many enamel rods are present in enamel?
Enamel is composed of millions of enamel rods.
How do the crystals in the enamel rod change during maturation?
They start off thin and become thicker as enamel matures through mineralization.
How are enamel rods organized within the tooth?
Enamel rods are found in rows along the tooth, with their long axes generally perpendicular to the underlying dentin and dentinoenamel junction (DEJ).
What is the orientation of enamel rods near the cusp tips?
Near the cusp tips, enamel rods run more vertically.
What is the orientation of enamel rods in the cervical enamel?
In the cervical enamel, rods run mostly horizontally.
How do enamel rods near the cementoenamel junction (CEJ) differ in permanent dentition?
In permanent dentition, enamel rods near the CEJ tilt slightly toward the root of the tooth.
How does the interlocking structure of enamel rods help to prevent fractures?
The interlocking structure of enamel rods provides supportto enamel, preventing fractures.
What are Hunter-Schreger bands?
Hunter-Schreger bands are alternating light and dark bands visible on a cross-section of tooth enamel under reflected light.
What causes the appearance of Hunter-Schreger bands?
They are caused by the sinusoidal bending of enamel crystals in rod groups at slightly different angles
What is the function of Hunter-Schreger bands?
They act as a reinforcing structure, increasing enamel’s resistance to fracture and wear.
What type of phenomenon are Hunter-Schreger bands considered?
They are considered an optical phenomenon caused by the way light interacts with differently oriented enamel prisms.
How do most enamel rods extend in the tooth?
Most rods extend all the way from the dentinoenamel junction (DEJ) to the outer enamel surface.
How is enamel structured near cusp tips?
Enamel rods interdigitate to form a complex structure known as gnarled enamel near the cusp tips.
What is the function of gnarled enamel?
Gnarled enamel reduces occlusal stress on enamel, especially at pronounced cusp tips of posterior teeth.
What would happen to enamel without the structure of gnarled enamel in high-use areas?
Without gnarled enamel, the enamel would shatter under occlusal stress.
How do rods in other areas of the crown contribute to enamel strength?
The interlocking rods in other areas of the crown contribute to the stiffness and hardness of enamel.
What surrounds the outer part of enamel rods?
The interrod enamel
What are the Lines of Retzius?
The Lines of Retzius are incremental lines (or striae) visible in a microscopic section of mature enamel.
What do the Lines of Retzius represent?
They represent periods of enamel formation during tooth development, marking pauses or changes in the rate of enamel deposition by ameloblasts.
How do the Lines of Retzius appear under a microscope?
They appear as dark bands under a microscope.
How do the Lines of Retzius run within the enamel structure?
They run obliquely from the dentinoenamel junction (DEJ) toward the enamel surface.
What enamel surface features are associated with the Lines of Retzius?
The lines often culminate in surface elevations called perikymata, with grooves known as imbrication lines and raised lines as perikymata.
What is the neonatal line?
The neonatal line is a pronounced line of Retzius corresponding to the birth of an individual.
What does the neonatal line demarcate?
It demarcates enamel formed prenatally and after birth.
What causes the neonatal line to form?
It forms due to trauma experienced by ameloblasts during birth, showing their sensitivity while forming enamel matrix.
What areas of enamel contain the neonatal line?
It is found in all the crown enamel of primary dentition and the larger cusps of permanent first molars.
What are the structural characteristics of enamel near the neonatal line?
Enamel crystals in this area have irregular structures with disordered arrangements.
What other conditions can produce accentuated incremental lines in enamel?
Systemic disturbances, such as fevers, can affect amelogenesis and produce accentuated incremental lines.
What are enamel spindles?
Enamel spindles are short dentinal tubules located near the dentinoenamel junction (DEJ).
Where are enamel spindles most commonly found?
They are most commonly found beneath the cusps and incisal ridges or tips of teeth.
How do enamel spindles form?
They form when odontoblasts cross the basement membrane before it mineralizes into the DEJ, leaving trapped dentinal tubules.
What are enamel tufts?
Enamel tufts are small, dark hypomineralized ribbon-like structures running longitudinally to the tooth axis.
Where can enamel tufts be observed?
They are best seen in transverse sections of enamel in the inner one-third of enamel.
Do enamel tufts have clinical significance?
They are considered anomalies of crystallization with no known clinical significance at this time.
What are enamel lamellae?
Enamel lamellae are partially mineralized vertical sheets of enamel matrix.
Where do enamel lamellae extend?
They extend from the DEJ near the tooth’s cervix to the outer occlusal surface.
What is mature dentin?
Mature dentin is a crystalline material that is less hard than enamel but slightly harder than bone.
What is the composition of mature dentin?
Mature dentin is 70% inorganic or mineralized material, 20% organic material, and 10% water.
What is the shape and size of crystals in dentin?
Crystals in dentin are platelike in shape and 30% smaller in size than those in enamel.
What is the primary crystalline component of mature dentin?
The primary crystalline component of mature dentin is calcium hydroxyapatite.
What is the chemical formula for calcium hydroxyapatite?
The chemical formula for calcium hydroxyapatite is Ca₁₀(PO₄)₆(OH)₂.
What is dentin covered by in the crown and the root of the tooth?
In the crown, dentin is covered by enamel, and in the root, it is covered by cementum.
What does the innermost part of dentin surround?
The innermost part of dentin surrounds the pulp tissue.
How does dentin appear in a radiograph compared to enamel and pulp?
Dentin appears more radiolucent than enamel but more radiopaque than pulp.
What does dentin make up in the tooth?
Dentin makes up the bulk of the tooth.
What color does dentin give to the tooth?
Dentin gives the tooth a yellowish-white color.
How does dentin differ from enamel in terms of organic content?
Dentin has a higher organic content than enamel.
What does the higher organic content of dentin allow it to do?
The higher organic content makes dentin softer than enamel but allows it to provide flexibility and support to the tooth.
What happens to the crown when the outer layers of enamel are lost?
When the outer layers of enamel are lost, newly exposed dentin on the crown appears yellow-white and has a rougher surface texture than enamel.
How does the lower mineralized content of dentin affect wear?
The lower mineralized content of dentin makes it wear more rapidly than enamel when subjected to attrition.
What does gingival recession and cementum loss expose?
Gingival recession exposes root dentin when the thin layer of cementum is lost.
How does root dentin differ from enamel in terms of sensitivity?
Root dentin is more sensitive than enamel due to its lower mineralized content.
What stimuli can cause pain in exposed root dentin?
Exposed root dentin transmits pain to the pulp in response to thermal changes, mechanical irritation, or osmotic changes.
Why is root dentin more susceptible to staining compared to enamel?
Root dentin is more susceptible to staining because it is more porous than enamel.
What can contribute to the stained appearance of exposed dentin?
Exposed dentin can accumulate stains from dietary sources such as coffee, tea, wine, or tobacco.
How does gingival recession increase the risk of root caries?
The increased risk of root caries arises due to biofilm accumulation, frequent exposure to dietary carbohydrates, and the absence of protective enamel covering.
Why does root dentin wear faster than enamel?
Root dentin wears faster because it has a lower mineral content and a softer composition compared to enamel.
What are some treatments for exposed root dentin?
Treatments include fluoride varnish application, desensitizing agents, and restorations to protect the exposed areas.
How can the progression of gingival recession be prevented?
Prevention involves addressing contributing factors such as periodontal disease, improper brushing techniques, and avoiding abrasive toothpaste.
What is dentinogenesis?
Dentinogenesis is the process of dentin matrix (predentin) formation that occurs during the apposition stage of tooth development.
How does the formation of dentin matrix differ from cartilage, bone, and cementum?
Unlike cartilage, bone, and cementum, the odontoblast’s cell body does not become entrapped in the product.
What is left behind by odontoblasts during dentin formation?
A long cytoplasmic attached extension remains behind in the formed dentin, creating a dentinal tubule.
How much predentin do odontoblasts form daily during tooth development?
Odontoblasts form approximately 4 micrometers of predentin daily during tooth development.
When does dentin maturation occur?
Dentin maturation occurs soon after its appositional growth.
What are the two phases of dentin maturation?
The two phases are the primary mineralization phase and the secondary mineralization phase.
What happens during the primary mineralization phase?
Calcium hydroxyapatite crystals form as globules in the collagen fibers of predentin, allowing for expansion and fusion.
What occurs during the secondary mineralization phase?
New areas of mineralization occur as additional globules form in partially mineralized predentin, layering on the initial crystals.
What results from incomplete fusion during the secondary mineralization phase?
Incomplete fusion creates differences in the microscopic appearance of crystalline dentin.
What is globular dentin?
A zone of dentin that appears as lighter, rounded areas in stained sections of teeth and is characterized by complete crystalline fusion.
What is interglobular dentin?
Interglobular dentin appears as darker, arc-like areas in a microscope where only primary mineralization has occurred, and the globules do not fuse completely.
What are dentinal tubules?
Dentinal tubules are long tubes in the dentin that extend from the dentinoenamel junction (DEJ) in the crown area, or the dentinocemental junction (DCJ) in the root area.
What happens to odontoblasts after the appositional growth of predentin and its maturation into dentin?
After appositional growth and maturation, the cell bodies of the odontoblasts remain in the pulp, along its outer wall, inside the tooth.
Is dentin vascular or avascular?
Dentin is avascular.
How do odontoblasts within the dentin receive nutrition?
Odontoblasts receive nutrition via tissue fluid in the dentinal tubules, which originates from blood vessels located in the adjacent pulp.
What does dentinal fluid in the tubules include?
Dentinal fluid presumably includes tissue fluid surrounding the cell membrane of the odontoblast, which is continuous with the cell body in the pulp.
What is the odontoblastic process?
The odontoblastic process is a long cellular extension located within the dentinal tubule that is still attached to the odontoblast’s cell body in the pulp.
What is the role of the odontoblastic process in dentin?
The odontoblastic process secretes hydroxyapatite crystals to mineralize the matrix and helps with dentin repair in mature teeth. It also participates in mechanosensation.
Does dentin have a uniform structure throughout the tooth?
No, dentin is not a uniform tissue within the tooth but differs from region to region.
How are certain types of dentin organized?
Certain types of dentin are designated by their relationship to the dentinal tubules. Other types of dentin are designated by their relationship to the enamel and pulp. Dentin can also be categorized according to the time that it was formed within the tooth.
What are the types of dentin related to dentinal tubules?
The types of dentin related to dentinal tubules are peritubular dentin and intertubular dentin.
What are the types of dentin related to the enamel and pulp?
The types of dentin related to the enamel and pulp are mantle dentin and circumpulpal dentin.
What are the categories of dentin based on the time of formation?
The categories of dentin based on the time of formation are primary dentin, secondary dentin, and tertiary dentin.
Where is peritubular dentin located?
Peritubular dentin is located in the walls of dentinal tubules and is highly mineralized.
Where is intertubular dentin found?
Intertubular dentin is located between the tubules and is less mineralized.
Where is mantle dentin located?
Mantle dentin is located at the outermost layer near the dentinoenamel junction.
What is circumpulpal dentin?
Circumpulpal dentin forms the layer around the outer pulp and is formed after mantle dentin.
What is primary dentin, and when is it formed?
Primary dentin is formed before the completion of the apical foramen and is more regular than secondary dentin.
When is secondary dentin formed?
Secondary dentin is formed after the completion of the apical foramen.
What is tertiary dentin, and when is it formed?
Tertiary dentin is formed as a result of local injury to exposed dentin and is irregular in structure.
Which predentin is the first to form and mature?
Mantle dentin
Does primary dentin regular or irregular pattern of tubules?
Primary dentin is characterized by its regular pattern of tubules.
When is most of the dentin in a tooth formed?
Most of the dentin in a tooth is formed during the primary dentin formation period.
What is secondary dentin?
Secondary dentin is formed after the completion of the apical foramen(s) and continues to form throughout the life of the tooth.
How does secondary dentin differ microscopically from primary dentin?
Microscopically, a dark line shows the junction between primary and secondary dentin.
How does secondary dentin contribute to the tooth’s structure over time?
Secondary dentin continues to form throughout the life of the tooth, adding to the overall dentin structure.
How does mantle dentin differ in its collagen fiber orientation?
Mantle dentin shows a difference in the direction of mineralized collagen fibers, which are perpendicular to the DEJ compared to the rest of the dentin.
What type of collagen fibers are associated with mantle dentin?
Large-diameter collagen fibers called von Korff fibers are associated with mantle dentin.
How does mantle dentin compare to inner dentin in mineralization?
Mantle dentin has more peritubular dentin than later-formed inner dentin, giving it higher levels of mineralization.
makes up the bulk of the dentin in a tooth.
Circumpulpal dentin
When does circumpulpal dentin form compared to mantle dentin?
Circumpulpal dentin forms and matures after mantle dentin.
How do the collagen fibers of circumpulpal dentin differ from mantle dentin?
The collagen fibers of circumpulpal dentin are mostly parallel to the DEJ, compared to the perpendicular arrangement in mantle dentin.
What is another name for tertiary dentin?
It is also called reparative dentin or reactive dentin.
How is tertiary dentin formed?
It is formed quickly in local regions in response to a localized injury to the exposed dentin.
What types of injuries can cause the formation of tertiary dentin?
The dentinal injury could be due to caries, cavity preparation, attrition, or gingival recession.
Where does tertiary dentin form?
It forms underneath the exposed dentinal tubules along the outer pulpal wall, trying to seal off the injured area.
What is sclerotic dentin?
It is a certain type of tertiary dentin.
Where is sclerotic dentin found?
It is found in association with the chronic injury of caries and is noted in increased amounts as the tooth ages.
What happens in the formation of sclerotic dentin?
In this type of dentin, the odontoblastic processes die and leave the dentinal tubules vacant.
What fills the tubules in sclerotic dentin?
The tubules are filled with peritubular dentin.
What happens to dentin during the shedding of primary teeth?
Dentin is resorbed during the shedding of primary teeth, and the dentin formed is mostly stable during the life of the tooth.
Can dentin become resorbed in permanent teeth?
Rarely, dentin can become resorbed in permanent teeth.
What is the cause of dentin resorption in permanent teeth?
The cause is unknown (idiopathic) and can involve either an internal or external resorption process.
How can dentin resorption be identified?
It can be noted radiographically, but it is hard to discern between internal and external resorption processes.
What is a pink tooth, and what does it signify?
A pink tooth is an early sign of internal tooth resorption.
What causes the pink tooth condition?
It occurs when the dentin or cementum of a tooth is absorbed into the tooth canal.
How can dentin become exposed and lost?
Another way dentin can become exposed and then lost is through dentinal caries.
What causes the demineralization in dentinal caries?
Demineralization results from cariogenic bacteria.
At what pH level does dentin begin to demineralize?
Dentin demineralizes when the pH is less than 6.8.
What conditions can lead to exposed dentin?
Exposed dentin can result from caries, cavity preparation, gingival recession, or attrition.
What symptoms can exposed dentinal tubules cause?
Open dentinal tubules may be painful for the patient, causing dentinal hypersensitivity.
What are the imbrication lines of von Ebner?
They are incremental lines or bands in a microscopic section of dentin.
What do the imbrication lines of von Ebner demonstrate?
They show the incremental nature of dentin during the apposition stage of tooth development.
How are the imbrication lines in the dentin oriented?
They run at 90° to the dentinal tubules.
What are the contour lines of Owen?
They are a number of adjoining parallel imbrication lines visible in a microscopic section of dentin.
What do the contour lines of Owen indicate?
These lines demonstrate a disturbance in body metabolism that affects the odontoblasts by altering their formation efforts, appearing as a series of dark bands.
What is the most pronounced contour line of Owen?
The most pronounced contour line is the neonatal line, which occurs due to the trauma of birth.
What happens to the diameter of the dentinal tubule with aging?
The diameter of the dentinal tubule narrows.
What causes the narrowing of dentinal tubules with age?
It is due to the deposition of peritubular dentin.
How does aging affect the pulp’s ability to react to stimuli?
With age, the pulp has a decreased ability to react to various stimuli.
What happens to the passageways of the tubules with age?
The passageways of the tubules to the pulp are not as wide open as they are at a younger age.
How is stimulus transmission affected by aging?
Stimuli are not transmitted as rapidly and in as large amounts as they were previously.
What changes occur in odontoblasts with age?
Odontoblasts undergo cytoplasmic changes, including a reduction in organelle content with age.
What can cause dentin to become more exposed with age?
Dentin becomes more exposed as a result of both attrition and gingival recession.
Does exposed dentin always lead to hypersensitivity?
Exposed dentin may or may not lead to dentinal hypersensitivity.
What is the pulp of a tooth?
The pulp is the innermost tissue of the tooth.
What type of tissue is the pulp?
The pulp is a connective tissue with all the components of such a tissue.
What are the components of pulp tissue?
The components include:
• Intercellular substance
• Tissue fluid
• Cells
• Lymphatics
• Vascular system
• Nerves
• Fibers
How does pulp appear on a radiograph?
Radiographically, pulp appears radiolucent (dark).
Why does the pulp appear radiolucent on a radiograph?
Pulp appears radiolucent because it is less dense than the radiopaque (or lighter) hard tissues of the tooth.
What role does the pulp play for the dentin?
The pulp is involved in the support, maintenance, and continued formation of dentin.
Where are the cell bodies of odontoblasts located?
The cell bodies of the odontoblasts remain along the outer pulpal wall.
What are the functions of the pulp?
The functions of the pulp include:
• Sensory: Detecting extremes in temperature, pressure, or trauma to the dentin or pulp, which are perceived as pain.
• Nutritive: Supplying moisture and nutrients to the organic components of the surrounding mineralized tissue.
• Protective: Forming reparative or secondary dentin (by the odontoblasts).
What is the apical foramen?
It is the opening from the pulp into the surrounding periodontal ligament (PDL) near the apex of the tooth.
What structures surround the apical foramen?
It is surrounded by layers of cementum and allows arteries, veins, lymphatics, and nerves to enter and exit the pulp from the PDL.
What happens if more than one foramen is present at the tooth apex?
The largest one is designated as the apical foramen, and the rest are considered accessory foramina.
What are accessory canals?
They are extra openings from the pulp to the periodontal ligament and may also be associated with the pulp.
What is another name for accessory canals?
They are also called lateral canals.
Where are accessory canals usually located?
They are typically found on the lateral surfaces of the roots of some teeth.
How are accessory canals formed?
They form when Hertwig epithelial root sheath encounters a blood vessel during root formation. The root structure then forms around the vessel, creating the accessory canal.
Do all teeth have accessory canals?
Not all teeth have accessory canals, and they are present in differing amounts in various tooth types.
Why is pulp considered a connective tissue?
Pulp is a connective tissue because it contains intercellular substance, tissue fluid, certain cells, lymphatics, vascular system, nerves, and fibers.
What is the largest group of cells in the pulp?
Fibroblasts are the largest group of cells in the pulp.
What is the second largest group of cells in the pulp?
Odontoblasts are the second largest group of cells.
Where are odontoblasts located in the pulp?
Odontoblasts are located only along the outer pulpal wall.
What type of stem cells are present in the pulp?
The pulp contains dental pulp stem cells (DPSCs), which are an undifferentiated mesenchymal type of stem cell.
What can DPSCs transform into?
DPSCs can transform into fibroblasts or odontoblasts if the cell population is reduced after injury.
What are the two types of nerves associated with the pulp?
Myelinated nerves and unmyelinated nerves.
What type of sensory function do most of the pulp nerves perform?
They are mostly nociceptors that relay the sensation of pain.
What are myelinated nerves, and where are they located?
Myelinated nerves are the axons of sensory or afferent neurons located in the dentinal tubules in dentin.
Where are the associated nerve cell bodies of myelinated nerves located?
These are located between the odontoblasts’ cell bodies in the odontoblastic layer of the pulp.
What are unmyelinated nerves associated with?
Unmyelinated nerves are associated with blood vessels.
Where do the nerve fibers for unmyelinated nerves in teeth originate from?
They originate from the mandibular and maxillary branches of the trigeminal nerve, with cell bodies located in the trigeminal ganglion.
How many zones are visible in the pulp under a microscope?
Four zones are evident microscopically.
What are the four zones of the pulp?
• Odontoblastic layer
• Cell-free zone
• Cell-rich zone
• Pulpal core
What does the organization of the pulp zones reflect?
The pulp cavity exhibits these four zones as you progress from the dentin-pulp junction toward the center of the pulp cavity.
What happens to the pulp horns with age?
The pulp horns recede with age.
What decreases in the pulp as it ages?
The pulp undergoes a decrease in intercellular substance, water, and cells, while the amount of collagen fibers increases.
What is a noticeable cellular change in aging pulp?
There is a reduction in the number of undifferentiated mesenchymal cells. Aka less stem cells
How does aging affect the pulp’s regenerative capacity?
Aging makes the pulp more fibrotic, leading to reduced regenerative capacity due to cell loss.
What changes occur in the overall pulp cavity with age?
The pulp cavity may shrink due to secondary or tertiary dentin deposition, causing pulp recession.
Why is there a lack of sensitivity in older teeth?
This is due to receded pulp horns, pulp fibrosis, dentin deposition, or other age-related changes.
What restorative treatment consideration is common for aging teeth?
Restorative treatment can often be performed without local anesthesia on mature dentitions in many cases.
What are pulp stones?
Pulp stones (or denticles) are mineralized masses of dentin sometimes present in the pulp.
What are the two structural types of pulp stones?
• True pulp stones: Mineralized masses of dentin with dentinal tubules and odontoblastic processes.
• False pulp stones: Amorphous in structure.
Where can pulp stones be located?
• They can be free or unattached to the outer pulpal wall.
• They can also be attached to dentin at the dentin-pulp interface.
When are pulp stones formed?
They are formed during tooth development and as the pulp ages, often due to microtrauma.
How common are pulp stones, and how are they detected?
They are quite common, filling most of the pulp chamber, and are detected as radiopaque masses on radiographs.
Are pulp stones problematic?
They are usually not an issue but can complicate endodontic therapy.
What is pulpitis?
Pulpitis is the inflammation of pulp tissue.
What are the three diagnostic categories of pulpitis?
• Reversible pulpitis: Quick, sharp hypersensitive response to thermal stimulus, non-lingering.
• Irreversible pulpitis: Lingering pain (lasting more than 10 seconds), spontaneous or elicited by a stimulus, with irreversible pulp damage.
• Necrotic pulp: Nerve becomes non-responsive, and the tooth may be asymptomatic or experience percussive pain.
How does pulp necrosis progress?
After pulp exposure by caries, necrosis and infection progress slowly in an apical direction, leading to apical periodontitis.
What is root canal therapy?
It is a procedure where necrotic pulp is surgically removed, and the pulp chamber is filled with an inert material (gutta-percha).
What happens to the tooth after the pulp is removed?
The tooth becomes non-vital as it no longer has a nutritional source from vascular pulpal tissue.
What complications arise in endodontically treated teeth?
They may darken, become brittle, and break during mastication.
What is used to protect a tooth after endodontic treatment?
A full-coverage restorative crown is placed to protect the tooth, improve retention.
What is done to the necrotic pulp?
The necrotic pulp is surgically removed, and the pulp chamber is filled with an inert material (gutta-percha).
What is used to protect a tooth after endodontic treatment?
A full-coverage restorative crown is placed to protect the tooth, improve retention, and enhance appearance if tooth-colored.
