TCDHA Histology Midterm Exam Questions and Answers 100% Accurate

Holocrine Glands entire cells are discharged as secretion (sebaceous glands)
Merocrine glands secrete product through free surface, no loss of cytoplasm/cell
Apocrine Glands secrete small amounts of cytoplasm/cell with secretory product (mammary glands)
unicellular goblet cells
Multicellular tubular, alveolar/acinus
Serous secretion clear, watery with protein
Mucous secretion cloudy, mucin (glycoproteins) with water
Compound tubularv alveolar merocrine glands
intercalated duct he duct which is attached to an acinus or terminal part of the gland
interlobar septa The connective tissue partitions between lobes are
interlobular septa he connective tissue partitions between lobules
Intercalated ducts hollow tube lined with simple cuboidal epithelium flat cells that do not produce secretion only serve as passageway for saliva
Striated ducts connected to intercalated duct lined with simple columnar epithelium cells which may have basal striation(mitochondria). Serves as passageway for saliva and modifies by resorbing and excreting electrolytes
Excretory/Secretory ducts starts as pseudostratified columnar epithelium and transforms to stratified cuboidal then ends as stratified squamous epithelium, passageway for saliva
hypoplasia pitting of enamel because of poor matrix formation (less than normal amount of enamel
Dental fluorosis mottled enamel, children exposed to more than 2ppm for 1st 8 years. Fluoride interferes with ameloblasts function
Abrasion abnormal wear cause by friction due to excessive tooth brushing or use of abrasive toothpastes.
Erosion tooth structure lost through chemical means such as acid from acid reflux, acidic foods/drinks or vomiting
Abfraction loss of tooth structure (wedge-shaped lesions) at the cervical neck area of teeth from transmission of forces during occlusion and mastication. Caused by compressive and tensile forces during tooth flexure.
What is acinus/acini? refers to any cluster of cells
What kind of epithelium surrounds the acinus? consists of a single layer of cuboidal epithelial cells
Salivary glands are Compound tubular-alveolar merocrine glands.
exocrine glands have a duct
simple duct one duct which does not branch
compound duct branching of a duct where the secretory unit empties into small ducts and these join to form larger ones.
Unicellular shape of Secretory Unit Single cell (Goblet)
Multicellular shape of Secretory Unit Tubular, Alveolar/Acinus
merocrine glands secrete product through free surface, no loss of cytoplasm/cell EX: salivary glands, pancreas
Apocrine glands secrete small amounts of cytoplasm/cell with secretory product EX: mammary glands
holocrine glands entire cells are discharged as secretion EX: sebaceous glands
intercalated ducts attached to acinus. passageway for saliva
striated ducts connected to intercalated ducts. cells resorb and excrete electrolytes.
excretory/secretory ducts start as pseudostratified columnar epithelium and changes into stratified caboidal and ends as stratified squamous epithelium.
major salivary glands carry secretion by main duct and secrete 90% of saliva. (parotid,submandibular,sublingual)
minor salivary glands empty their products by short ducts. (labial, buccal, palatine, lingual, von ebner’s)
The functional unit of the salivary gland is alveolus or acinus
palatine glands hard and soft palate
lingual glands posterior
von ebner’s salivary gland posterior dorsum tongue (circumvallate papillae)
how much saliva is produced daily? 640mls
Fordyce granules visible sebaceous glands that are present in most individuals. They appear on the genitals and/or on the face and in the mouth.
mucocele is a fluid-filled swelling that occurs on the lip or the mouth.
Sialolithiasis condition where a calcified mass or sialolith forms within a salivary gland, usually in the duct of the submandibular gland
Xerostomia dry mouth and dry mouth syndrome, is dryness in the mouth, which may be associated with a change in the composition of saliva, or reduced salivary flow, or have no identifiable cause.
Mums viral disease caused by the mumps virus. Initial signs and symptoms often include fever, muscle pain, headache, and feeling tired. This is then usually followed by painful swelling of one or both parotid salivary glands
ranula type of mucocele found on the floor of the mouth. Ranulas present as a swelling of connective tissue consisting of collected mucin from a ruptured salivary gland caused by local trauma
Sjogren’s Syndrome disorder of your immune system identified by its two most common symptoms dry eyes and a dry mouth. The condition often accompanies other immune system disorders, such as rheumatoid arthritis and lupus
Oral Mucosa of stratified squamous epithelium overlying a layer of connective tissue proper or lamina propria. There may be a deeper layer of submucosa present
basement membrane lies between the epithelium and lamina propria in the oral mucosa
Floor of the mouth non-keratinized, submandibular and sublingual salivary glands, Lamina Propria has extensive vascular supply, broad connective tissue papillae
Cheek/Buccal non-keratinized. lamina propria has extensive vascular supply. adipose tissue and minor salivary glands.
tongue body composed of? skeletal muscle
tongue root composed of? anchored to the hyoid bone and is covered with lingual tonsils.
What is the function of the lingual papillae? They are found on the upper surface of the tongue, scattered amongst the filiform papillae but are mostly present on the tip and sides of the tongue. They have taste buds on their upper surface which can distinguish the five tastes: sweet, sour, bitter, salty, and umami.
What connects tongue to floor of the mouth? median fold of mucous membrane, the frenulum
What is frenectomy and why is it done? ankyloglossia treatment
what are taste buds any of the clusters of bulbous nerve endings on the tongue and in the lining of the mouth that provide the sense of taste.
function of taste buds? contain the taste receptor cells, which are also known as gustatory cells. The taste receptors are located around the small structures known as papillae found on the upper surface of the tongue, soft palate, upper esophagus, the cheek and epiglottis
location of taste buds upper surface of the tongue, soft palate, upper esophagus, the cheek and epiglottis
Hyperkeratinization Tissue response to frictional or chemical trauma (chronic trauma).
Where is the enamel located? Tooth enamel is a hard substance found in the crown of each of your teeth and is the part of the tooth that’s visible when you look in your mouth
composition of enamel ? 96% inorganic (mineralized)
enamel is avascular and non vital (has no nerves)
Amelogenesis Process of enamel matrix formation and mineralization.
Enamel matrix is? ectodermal derived from inner enamel epithelium (IEE) of the enamel organ.
when does enamel matrix occur? appositional stage (formation of enamel/dentin matrix) of tooth development.
enamel matrix does not contain? collagen
where is the enamel first formed? cusp/tip
enamel matrix secreted by? Tomes process
enamel pearl condition of teeth where enamel is found in locations where enamel is not supposed to be, such as on a root surface. They are usually found in the area between roots, which is called a furcation, of molars
Enamel dysplasia defect of the teeth in which the enamel is hard but thin and deficient in amount, caused by defective enamel matrix formation. Usually the condition involves part of the tooth having a pit in it
What can be placed to seal off deep pits and fissures? Tooth sealants
what secretes enamel matrix? rough endoplasmic reticulum
How are rods aligned? perpendicular to the DEJ except in cervical regions of permanent teeth (towards root)
What pattern are rods aligned in? interlocking
Lines of RETZIUS concentric series of bands, on enamel rods, represent incremental growth lines that extend from DEJ
Neonatal Line pronounced line of retzius marked by stress/trauma experienced by ameloblasts during birth
Nasmyth’s membrane a delicate membrane covers the entire crown of the newly erupted tooth. Green or yellow is easily worn away
Hunter-Shreger Bands change the direction of rods from one prism to the next. Originate from DEJ and run perpendicular to lines of retzius. Altering zones have different mineral content, which allows for adaption of occlusal forces.
Perykimata external manifestation of lines off retzius. Areas on tooth where groups of ameloblasts stopped functioning in cervical 2/3 of crown, continuous around the tooth and parallel to CEJ.
Enamel Spindle sometimes odontoblastic processes (dentinal tubules)pass across DEJ into enamel and become trappend and are then termed enamel spindles. Noted beneath the cusps and incisal tips of the teeth.
Enamel Tufts small, dark brushes with bases that arise at or near right angles to the DEJ and extend a third of the way into the thickeness of the enamel. They represent areas of less mineralization
Enamel Lamella (lamellae) partially mineralized vertical sheets of enamel matrix. Transeverse cracks from occlusal surface of enamel to DEJ. Longer and narrower than enamel tufts
Hypoplasia pitting of enamel because of poor matrix formation (less than normal amount of enamel
Hypocalcification chalky areas because of incomplete or lack of maturation, deficiency of mineral content (Ca), enamel didn’t form properly.
Dental fluorosis mottled enamel, children exposed to more than 2ppm for 1st 8 years. Fluoride interferes with ameloblasts function
Decalcification chalky areas because it decalcified due to acids or poor oral hygiene. (white/brownish color)
Attrition wearing away of tooth structure from ordinary forces of occlusion. (tooth to tooth contact)
dentin avascular and vital (has nerves)
Mature dentin 70% inorganic – calcium hydroxyapatite. 20% organic
Crystals in dentin “””plate like”” and smaller than those in enamel”
Dentinogenesis process of dentin formation.
where does dentin form? forms from the dental papilla (mesenchymal) of the tooth germ
Predentin initial layer laid down by the odontoblasts
Apposition of dentin occurs throughout the life of a tooth
MANTLE DENTIN outermost layer, first predentin
CIRCUMPULPAL DENTIN surrounds the outer layer of the pulp, bulk of the dentin
Primary Dentin before completion of apical foramen
Secondary Dentin after completion the apical foramen
Tertiary Dentin reparative dentin
Mineralization occurs by budding
mantle dentin Small odontoblastic buds provide loci of crystallizations, which join and grow in 3 dimensional
Formation and calcification starts at? the cusp
Peritubular dentin dential matrix that immediately surrounds the dentianal tubule like a wall of tubules.
Intertubular dentin in between the tubules
DENTINAL TUBULES long tubes in the dentin that extend from the DEJ to the outer wall of the pulpv
what causes Dentin Hypersensitivity due to the exposure of dentin, the part of the tooth which covers the nerve, either through loss of the enamel layer or recession of the gums. Temperature changes and certain foods (acidic or sweet) can cause the tooth or teeth to be painful.
what is Hydrodynamic Theory of Dentinal Hypersensitivity? It is believed that DH is made as the result of movement of the fluid inside the dentinal tubules, which is further due to the thermal and physical changes, or as the result of formation of osmotic stimuli near the exposed dentine.
what is Incremental lines of Von Ebner? The lines of von Ebner represent cyclic activity of the odontoblasts during dentin formation.
what are Neonatal lines? pronounced line of retzius marked by stress/trauma experienced by ameloblasts during birth
what is Tome’s granular layer? ound in root area of tooth just below cementum. It is thin, hypomineralized spotted areas giving it a granular appearance. Cause=unknown
what is Dentinogenesis imperfecta? If dentin is poorly formed, enamel will chip off
what are Dead Tracts ? Empty tubules resulting from loss of the odontoblastic processes or odontoblast death
Sclerotic Dentin Transparent dentin, Tubules become completely calcified as a result of injury(caires) or normal aging. Odontoblastic processes die and leave dentinal tubules vacant.
what is Internal Resorption? process by which all or part of a tooth structure is lost due to activation of the body’s innate capacity to remove mineralized tissue, as mediated via cells such as osteoclasts. Types include external resorption and internal resorption. It can be due to trauma, infection, or hyperplasia
what are Dentinal Caries? scientific term for tooth decay or cavities. It is caused by specific types of bacteria. They produce acid that destroys the tooth’s enamel and the layer under it, the dentin. … They build up on the teeth in a sticky film called plaque.
what is pulp? Connective tissue. Mesenchymal, derived from the dental papilla (like dentin).
what is the Odontoblastic zone? Closest to the dentin layer which lines the outer pulpal wall Contains layer of the cell bodies of odontoblasts, Capable of forming secondary/tertiary dentin along the pulpal wall
what is the Cell free zone/ zone of weil? Subodontoblastic layer, nerve and capillary plexus located here, Contains fewer cells than odontoblastic zone
Cell rich layer Many cells but fewer than odontoblastic zone. Extensive vascular supply
Pulp core Major vessels and nerves, similar to cell rich layer
Blood supply Large cylindrical vessels. Nutrition obtained through the tubules and their connection to the odontoblasts.
nerve supply Cell bodies of afferent axons lie in the dentinal tubules. Changes in temperature, vibrations, and chemical changes are perceived only as PAIN.
What is pulpal mode of entry? Apex. Accessory canals.
What is pulpitis? inflammation of dental pulp tissue
What can happen to the pulp with age? CT fibers and pulp stones (denticles) increase.
True denticles (pulp stones) rare, close to apex similar to dentin because they exhibit dental tubules containing odontoblastic processes
False denticles (pulp stones) no dentinal tubules, concentric layers of calcified tissue with bundles of collagen fibers
free pulp stone surrounded by pulp tissue, lie free In pulp
attached pulp stone fused with dentin
embedded pulp stone surrounds by dentin
What is enamel? Hardest calcified/mineralized tissue in the human bodyCovers Anatomical crown
What is the blood supply of enamel? Avascular and non-vital (has no nerves)
What is the material makeup of enamel? 96% inorganic (mineralized) material – mainly calcium hydroxyapatite3% water1% organic – enamelin (protein component)
What color is enamel? It is grayish/bluish white but appears slightly yellow b/c its translucent and the underlying dentin is yellowish
What is amelogenesis Process of enamel matrix formation
Where is enamel matrix derived from? Enamel matrix is ectodermal and is derived from inner enamel epithelium (IEE) of enamel organ
What stage does amelogenesis occur in? During the appositional stage (formation of enamel/dentin matrix) of tooth development
What is enamel matrix composed of? At first is composed of proteins, carbohydrates and small amounts of calcium hydroxyapatite crystalsit DOES NOT contain proteins like dentin, cementum and alveolar bone
What must be present in amelogenesis? Dentin must be present
Where is enamel first formed? Enamel is first formed in the cusp/ tip area of a tooth
Ameloblasts Produce enamel matrix
Tomes process – secretes enamel matrix- 6 sided pyramidal shaped projection of ameloblast facing DEJ( guiding factor of laying down enamel)
Where is enamel present in? It is present on the anatomical crown area ONLY
Enamel pearl Small, spherical enamel projections on root surface
Enamel dysplasia Faulty development of enamel
Deepened pits and fissures Is common and occurs when ameloblasts back into one another during stage of apposition, cutting off their source of nutrition, which causes incomplete maturation of enamel matrix(These areas may become target areas for dental caries)
Sealants used in the prevention of caries
What is mineralization? (Complete/incomplete/immediate/not immediate) It is complete and immediate
What do ameloblasts actively pump? Ameloblasts actively pump calcium hydroxyapatite into the forming enamel matrix as it is secreted by tome’s process
What do ameloblasts become part of after enamel apposition? When ameloblasts are finished with enamel apposition and maturation, they become part of the Reduced Enamel Epithelium (REE)
What happens to ameloblasts after tooth erupts? Ameloblasts are then lost forver once tooth erupts, therefore prevent further apposition of enamel
How does a newly erupted tooth continue to mineralize? A newly erupted tooth will continue to mineralize post-eruption by taking up materials from saliva
Enamel rod Structural unit of enamel
What is enamel composed of? Enamel is composed of millions of enamel rods surrounded by interrod enamel (tail) and rod sheaths ) microscopic spaces between rods
What shape are enamel rods? Key hole shaped (head in between 2 adjacent tails)Interlocking patter adds strength and durabilityHead point occlusally (crown), tails point cervically (Root)
How are enamel rods aligned? Rods are aligned perpendicular to the dentinoenamel junction (DEJ), except in the vercial regions of permanent teeth
Where are enamel rods thickest and thinnest? Rods are thickest at the cusps and thinnest at CEJ
Lines of retzius (enamel) Seen with transmitted lightAre concentric series of bands, on the enamel rods, represent incremental growth lines that extend from DEJ
Neonatal line (enamel) A pronounced line of retzius marked by stress/trauma experienced by ameloblasts during birth
Nasmyth’s membrane (enamel) – Primary enamel cuticle- a delicate membrane covers the entire crown of the newly erupted teeth. It is green or yellow and is easily worn away
Hunter- schreger bands (enamel) – seen w/ reflected light – change in direction of rods from one prism to next- originate from DEJ and run PERPENDICULAR to lines of retzius- STRENGTH AGAINST FORCE
Perikymata (enamel) – external manifestation of lines of retzius- raised grooves om the enamel surface- areas on tooth where groups of ameloblasts stopped functioning in cervical 2/3 of crown, cotinous around the tooth and PARALLEL to CEJ – seen w/ naked eye, w age they flatten and disappear
Enamel spindles – Odontoblastic processes (dentinal tubules) that pass across DEJ into enamel and become trapped
Where are enamel spindles found? Found beneath the cusps and incisal tips of the teeth
Enamel tufts “- small dark “”brushes”” with bases that arise at or near to the DEJ at right angles, amd extend 1/3rd of the way into the thickness of the enamel- represent areas of lexx mineralization”
Enamel lamellae – partially mineralized vertical sheets of enamel matrix- transverse cracks from occlusal surface of enamel to DEJ- longer and narrower than enamel tufts
Hypoplasia Pitting of enamel b/c of poor matrix formation (less than the normal amount of enamel)
Hypocalcification Chaly areas due to incomplete or lack of maturation, deficiency of mineral content (Ca), enamel did not form properly
Decalcification Chalky areas b/c enamel decalcified due to acids or poor oral hygiene
Dental fluorosis – Mottled enamel, children exposed to more than 2ppm for first 8 years – fluoride interferes w ameloblasts function
Attrition WEARING AWAY of tooth structure from ORDINARY FORCES of occlusion (tooth-to-tooth contact)
Abrasion Abnormal WEAR caused by friction due to exessive tooth brushing or use of abrasive toothpastes
Erosion Tooth structure LOST through chemical means such as acids from acid reflux, acidic foods/ drinking or vomiting
Abraction LOSS of tooth structure (Wedge-shaped lesions) at the CERVICAL NECK AREA. Of teeth from transmission of forces during occlusion and mastication. Caused by compressive and tensile forces during tooth flexure
What does dentin constitute? Constitutes the bulk of the tooth
What is the blood supply of dentin? Avascular and vital (has nerves)
What is the material makeup of mature dentin – 70% inorganic – calcium hydroxyapatite (softer than enamel, more porous – implications for debridement/caries/staining)- 20% organic- 10% water
Dentinogenesis Proces of dentin formation
Where does dentin and pulp form from? Forms from dental papilla (mesenchymal) of tooth germ (odonblasts ome from dental papilla)
Predentin – initial dentin matrix Non- mineralized mesenchymal product containing collagen fibers
What is predentin laid down by? Odontoblasts (Cells that produce dentin)
What happens to odontoblasts in predentin? Odontoblasts do not become trapped in the dentin, but rather leave behind one long cytoplasmic extension (odontoblastic process) in the formed dentin
What happens in dentinogenesis as organix matrix forms? As organic matrix forms, odontoblasts move AWAY from the DEJ producing predentin in layers (apposition)
When does apposition of dentin occur? Apposition of dentin occurs throughout the life of a tooth because odontoblasts remain in tooth along the other pulpal wall
When does maturation of dentin (mineralization of predentin) occur? Occurs soon after apposition
Primary phase (maturation of dentin) Hydroxyapatite crystals form as globules in the collagen fibres of the predentin (primary dentin) which allow expansion and fusion
Secondary phase (maturation of dentin) – further mineralization (secondary dentin) will occur as globules form in partially mineralized areas- areas of crystal formation are layered on the initial crystals, but fuse incompletely
How does mineralization occur? Mineralization occurs by budding
What do small odontoblastic buds provide? They provide location for crystallizations that join and grow in a 3-dimensional process to form mantle dentin (1st formed dentin, different from circumpulpal dentin)
When do collagen fibers within predentin begin to calcify? Within 24 hours
Where does formation and calcifcation of dentin happen? Starts at the cusp and moves inward towards the pulp
Mantle dentin – (outermost layer) the first predentin that forms and matures within the tooth
Where is the mantle dentin deposited? It is deposited first along the DEJ and has higher levels of mineralization
What is the direction of mineralized collagen fibres in mantle dentin? Mineralized collagen fibres are PERPENDICULAR TO DEJ
Circumpulpal dentin Surrounds the other layer of the pulp (forms after mantle dentin)Makes up bulk of the dentin
What is the direction of mineralized collagen in circumpulpal dentin? Mineralized collagen fibres are PARALLEL to DEJ
Primary dentin – first dentin made, BEFORE completion of apical foramen of root- major component of crown and root- more irregularities, less tubules, less mineralization
Secondary dentin – made as the teeth erupt and AFTER the apical foramen is completed- continues to form throughout the life of the tooth- formed more slowly than primary dentin- same mineral content as primary dentin
Tertiary dentin/ reparative dentin – forms quickly in response to injury to protect pulp (caries, attrition, recession)- if the odontoblasts become injured, undifferentiated mesenchymal cells of the pulp move in and become odontoblasts
Dentinal tubules Long tubes in the dentin that extend from the DEJ in crown area, or dentinocemental junction (DCJ) in the root area, to the other wall of the pulp
Within each dentinal tubules what are there? – odontoblatic processes- dentinal fluid (tissue fluid from pulp)- afferent (Sensory) axon – pain
Peritibular dentin – walls of the tubules- dentinal matrix that immediately surrounds the dentinal tubule
Intertubular dentin In between the tubules (main body of dentin)
Dentinal hypersensitivity Dentinal tubules may become open due to caries, recession, attrition, cavity preparation
What can dentinal hypersensitivity be triggered by? – thermal ( cold water from a/w syringe)- mechanical (ultrasonic debridement)- dehydration (air)- chemical exposure (acidic foods, tooth whitening)
What is dentinal hypersensitivity pain due to? Pain is due to changes in the dentinal fluid associated with the odontoblastic processes(Evaporation and loss of dentinal fluid, movement of the fluid, and ionic changes in the fluid)
Desensitizing toothpastes (sensodyne/colgate) Sensodyne: interferes w/ nerve transmissionColgate pro relief: occluding agents (oxalates, stannous fluoride) that block open tubules- must wear daily or protective layer washes away and sensitivity returns
Fluroide varnishes “-5% sodium fluoride varnishes are sticky and “”plug up”” the tubules- provides relief for weeks to months and needs to be replaced as needed”
Incremental lines of von ebner (dentin) – all dentin is deposit incrementally- certain amount of matrix deposited daily, a hesitation of activity follows resulting in an alteration in the matrix run in rings or bands, perpendicular to dentinal tubules
Neonatal lines (dentin) Accenuated incremental line seen in dentin caused by changes occuring at birth
Where is the tomes granular layer found? Found in the root area of tooth just below cementum
Tomes granular layer (dentin) Thin, hypomineralized spotted areas giving it a granular appearance (Causes are unknown)
Dentinogenesis imperfecta – shiny opalescent dentin- hereditary- if dentin is poorly formed, enamel will chip off
Dead tracts Empty tubules resulting from loss of the odontoblastic processes or odontoblast death
Sclerotic dentin (transparent dentin) – form of tertiary dentin- often found in areas with chronic injury or caries- odontoblastic processess die and leave the dentinal tubules empty- tubules become completely calcified as a result of injury (caries) or normal aging
Pulp Inntermost tissue of tooth and is considered connective tissue
Where is pulp derived from? Mesenchymal, derived from the dental papilla (like dentin)
What does the pulp consist of? – intercellular substances- fibroblast – connective tissue- odontoblast- collagen and reticular ribers (no elastic fibres)- wbcs- vascular system and nerves
Odontoblastic zone – closest to dentin, lines outer pulpal wall- contains cell bodies of odontoblasts- capable of forming secondary/ tertiary dentin along pulpal wall
Cell free zone/ zone of weil – contain fewer cells than odontoblastic zone- nerve and capillary plexus located here
Cell rich layer – many cells but fewer than odontoblastic zone- extensive vascular supply
Pulp core – cebter of the pulp chamber- major vessels and nerves, similar to cell rich layer
blood supply to pulp – large cylindrical vessels thats connected w blood vessels of periodontal ligament
Where is nutrition supplied to dentin obtained from? It is obtained through the tubules and their connection to the odontoblast’s cell bodies that line the outer pulpal wall
Nerves in pulp – cell bodies associated w/ afferent (sensory) axons lie in the dentinal tubules, pass through apex and branch out – changes in temp, vibrations, and chemical changes can be perceived as painful stimuli (require local anaesthesia for pain control during most restorative procedures)
What sensation does the pulp feel? All sensations that the pulp fells are perceived as PAIN
Pulp mode of entry – apex- lateral/ accessory canal
Pulp inflammation/ pulpitis Injury to pulp from caries, cavity preparation or other trauma, may result in pulpal infection in the form of a periapical abscess which will require endodontic treatment
Pulp with age – vascularity and cells decrease- CT fibers and pulp stones (denticles) increase
True denticles (pulp stones) Rare, close to the apex similar to dentin b/c they exhibit dental tubules containing odontoblastic processes
False denticles (pulp stones) No dentinal tubules, concentric layers of calciied tissue with bundles of collagen fibers
3 types of Denticle/ pulp stone 1. Free- surrounded by pulp tissue, lie free in pulp2. Attached – fused w/ dentin3. Embedded – surrounded by dentin
Cementum Specialized connective tissue, can form throughout the life of the tooth
What does the cementum cover? Covers the entire root
Where is the cementum thinnest/thickest? Thickest at apex and interradicular areas (between roots)Thinnest at CEJ
Where is the cementum located? On top of the tomes granular layer in dentin
What is the blood supply of cementum? Avascular and non-vital (no nerve supply)
Where does cementum develop from? Dental sac
HERS (Hertwig’s epithelian root sheath) A portion of cervical loop that functions to shape the root(s) and induce root dentin formation
When does cementum form? Forms on the root shortly after the disintegration of HERS The disintergration of shealh allows for undifferentiated cells of the dental sac to contact the root dentin surface and influence these cells to become cementoblast
What does the disintegration of the seath allow for? Allows for undiffertated cells of the dental sac to contact the root dentin surface and influence the cells to become cementoblasts
Cementoid The organic matrix of cementum
Where do cementoblasts spread over during cementogenesis? Cementoblasts spread over the root dentin and undergo cementogenesis, laying down cementoid
Cementoi Young matrix
Cementocytes Cementoblasts that become trapped in the cementum
Where does each cementocyte lie in? In its lacuna, the lacunae have canaliculi which have cementocytic processess oriented towards the PDC that help diffuse nutrients from the vasculatrized PDL
What happens when the cmentoid reaches full thickeness? The cementoid surrounding the cementocytes become mineralized (or matured) and is then considered cementum
When do cementoids start to calcify? Once the cementoid is formed and reached its proper thickness
What happens to the cementoblasts that were not trapped in cementum? They line up along the outer surface of the cementum; these cementoblasts can form cementum in case of injury
The formation of cementum is.. Ongoing (continues throughout life like dentin)
What is cementum composed of? Mineralized fibrous matrix and cells65% inorganic – hhydroxyapitate crystals23% organic – collagen fibers and chondroitin 12% water
What is fibrous matrix consist of? Consist of both sharpey fibers and intrinsic non-periodontal fibers
Sharpey fibers Part of the collagen fibers from the PDL which are partially inserted into the cementum at one end and alveolar bone at the other end at a right angle
What do sharpey fibers function as? A ligament between the bone and cementum
What are the intrisic non-PDL fibers of the cementum? Collagen fibres made by the cementoblasts
What happens to the cementoblasts that do not become entrapped in cementum? They line up along the cemental surface and repair the tooth if its injured
Where is acellular (primary) cementum deposited and where does it extend? 1st layer is deposited at DCJ (dentinalcemento junction) Extends from CEJ to apex (thinnest at apex)
What are the incremental lines like in acellular cementum? Incremental lines are parallel to the root surface Width never changes
What does acellular contain? Contains no embedded cementocytes
Where is the location of cellular (secondary) cementum? On the surface of acellular cementum
Where is cellular cementum thickest? Thickest around apex and in between roots (contributes to lengthening of root)
How does the width of cellular cementum change? Width may change during the life of tooth from (trauma, demineralization) especially at apex
Where is acellular cementum layered? At least one layer over entire root with many layers near cervical one-third
Where is cellular cementum layered? Layered over acellular, mainly in apical one-third, especially in interradicular region
Hypercementosis Excessive production of cellular cementum, mainly at apices
What are the causes of hypercementosis? 1. Chronic periapical inflammation2. Occlusal trauma3. Compensatory mechanism in response to attrition to increase occlusal tooth height
What can hypercementosis result in? May result in pulpal necrosis by blocking blood supply via the apical formaen
Cementicles Mineralized, spherical bodies of cementum in PDL caused by apposition of cementum around cellular debris
What is the cause of cementicles? Is it cellular/cellular? Unknown cause, and is acellular
What are the types of cementicles? Free – in the ligamentAttached – to surface of cementumEmbedded – within the cementum
Periodontal ligament Fibrous connective tissue between the alveolar bone and the cementum that supports the teeth
What does the periodontal ligament occupy? Occupies periodontal space between lamina dura and cementum
What is the PDL composed of? Composed of fibers, cells, and intercellular substance, composed of collagen fiber bundles that attach the cementum to the alveolar bone
What does the PDL contain? Blood vessels that supply nutrition to the surrounding tissue and bone (alveolar process)Has nerves that allow us to feel even the most delicate forces applied to the teeth (proprioceptive mechanism)
What does the PDL transmit? Pain, touch, pressure and temperature changes
What does the PDL act as? Acts as a shock absorber to protect delicate soft tissue structure that surround the teeth
What does a PDL appear as on a radiograph? Appears as a radiolucent space 0.4-1.5mm between lamina dura and cementum
What are the 2 types of nerves in the PDL? 1. Afferent2. Autonomic
Afferent (sensory, myelinated) nerves PDL Transmits sensations that occur within PDL (pain, touch, pressure and temperature changes)
Autonomic (sympathetic) nerves PDL Regualtes blood vessels
Principle Groups of PDL fibers Gingival fiber – located around necks of teeth, supports only marginal gingivaalveolodental ligament- surrounds the roots of teeth (main principle fiber group)interdental ligament or reansseptal ligament – cervical surface of adjacent teeth, cementum to cementum
Dentinogingival (gingival fiber group) – most extensive- inserts into cementum, extends into lamina propria of marginal gingiva
Alveologingival (gingival fiber group) – radiates from alveolar crest (bone), extends coronally into lamina propria of marginal and attached gingiva
Dentinoperiosteal (gingival fiber group) From cementum across alveolar bone
Circular/ circumferential ( gingival fiber group) Continuous around the neck of tooth
Apical (alveolodental ligament) – from cementum around apex of root to alveolar bone proper, forming base of alveolus – resists extrusive and rotational forces
Oblique (alveolodental ligament) – apical 2/3 of root to adjacent alveolar bone proper- resists intrusive and rotations forces
Alveolar crest (alveolodental ligament) – cervical root to alveolar crest of alveolar bone proper- resists tilting, intrusive, extrusive, rotational forces
Horizontal (alveolodental ligament) – runs at right angle to long axis just apical to alveolar crest- resist tilting and rotational forces
Interradicular (alveolodental ligament) – found only between roots of multirooted teeth- from cementum to cementum only, no bony attachment- resist intrusive, extrusive, tilting, rotational forces
Interdental ligament/ transseptal ligament – cervical surface of adjacent teeth- from cementum to cementum, no bony attachment- resist rotational forces and hold the teeth in interprox contact
Alveolar bone/process/ridge Part of the maxilla and mandible that contains the roots of the teeth; it supports and protects the teeth
What is the alveolar bone composed of? Alveolar bone proper/ lamina duraAlveolar crestSupporting bone
Alveolar bone proper Thin layer of compact bone, continuation of the cortical plate, forms tooth socket
Alveolar socket (alveolus) Cavity within the alveolar process where the roots of the teeth are held by the PDL
Supporting bone Compact bone (cribform plate) and cancellous bone (spongy, trabecular bone)
Interdental septum Bone that divides one tooth socket from another
Interradicular septum Bone that divides the roots of the same tooth
What is the makeup of alveolar bone? 60% inorganic25% organic15% water
Lamina dura – alveolar bone proper on radiographs- lines the socket and composed of compact bone
Alveolar crest (alveolar bone) – highest point of alveolar ridge- joins facial and lingual cortical plates- is the coronal border of the alveolar process (1-1.5 mm below CEJ)
What is the cortical plate/bone composed of ? Composed of lingual and facial plates of compact bone of the alveolar process
What does the cortical plate/ bone provide? It is dense and provides strength and protection, acts as the attachment for skeletal muscles
Which is more dense? Max or mand cortical plate? The mandibular cortical plate is more dense than the max cortical plate The mand CP has fewer perforations for the passage of nerves and blood vessels
The cortical bone/plate is only visible on occlusal radiographs (T or F) True
Where is the supporting cancellous/ spongy/ trabecular bone located? Located between the alveolar bone proper and the plates of cortical bone
What is the supporting cancellous bone composed of? Composed of heavy trabecili or plates of bone with bone marrow spaces between them
What does bone marrow contain? Contains blood forming elements, osteogenic cells and adipose tissue
Where is the spongy bone found? Within the central portion of the alveolar process and is the less dense, cancellous bone
What does the trabecular bone look like on an xray? Has a web- like appearance on radiographs
Fenestration The area of bone loss where an apical root penetrates the cortical bone, opening through the bone Window-like defect
Dehiscence Bone loss in the coronal area of the root, bone splits open
Where is leeway space created? It is created in the arches by the replacement of larger (mesidodistally) primary molars by smaller permanent (mesiodistally) premolars)
What does stress on the alveolar bone process cause? The stresses cause activation of cells (osteoblast/osteoclasts) and changes in the vascular and neutral tissue along the bone and cemental surfaces that are mediated through the PDL
Induction Action of one group of cells on another
Proliferation Controlled cellular growth and accumulation of byproducts (interstitial growth/ appositional)
Differentiation Change in identical embyotic cells to become distinct (Structurally and functionally) to perform specialized functions – effect cells, tissue typesm organs and systems
Morphogenesis The process of development of specific tissue structure or shape. Complexity of structure and function of cells increases
Maturation Attainment of adult function and size of tissues and organs due to the processes of proliferation, differentiation and morphogenesis
When is the preimplantation period? 1st week after conception
During fertiilization where does the final stages of meiosis occur Occurs in the ovum
After fertilization, what does the zygote undergo? Mitosis
Morila A solid ball of cell that forms after initial cleavage
Blastocyte/ blastula What the morula becomes after continuing undergoing mitosis
Where do blastocytes travel? From the fallopian tube to the uterus
When does the embryonic period occur? Beginning of 2nd week to the end of the 8th week
What happens during the 2nd week of prenatal development? The implanted blastocyst grows by increased proliferation of the embryonic cells
Embryonic cell layers What is created by an increased number of embryonic cellEctoderm, mesoderm and endoderm
Bilaminar embryonic disk Developed from the blastocyst, appears as a 3d flattened, circular plate of bilayered cells
What does the bilaminar embryonic disk have? – superior epiblast layer- inferior hypoblast layer
What does the bilaminar embryonic disk develop into? It will layer develop into an embryo
When does the primitive streak form? During the beginning of the 3rd week within the bilaminar disc
Where do cells from the epiblast layer move in the area of primitive streak They will migrate towards the hypoblast layer in the area of primitive streak.
How do epiblast and hypoblast layers become mesoderm and endoderm? Migratory cells move to the middle between epiblast and hypoblast layers – becomining mesoderm and endoderm
Trilaminar embryonic disk With 3 layers being present after migratory cells move between epiblast layer, the bilaminar embryonic disk is now caled trilaminar embryonic disk (epiblast layer, migratory cells, hypoblast)
Primary embryonic layers or primary germ layers Ectoderm, mesoderm, endoderm
What can the endoderm layer become? – digestive system- liver- pancreas- lungs (inner layers)
What can the mesoderm layer become? – circulatory system- lungs (epithelial layers)- skeletal system- muscular system
What can the endoderm layer becomes? – hair- nails- skin- nervous system