Dental Pulp Notes

Dental Pulp - Dental pulp makes a total volume of 0.38mL, although the pulp of the molars 4X larger than those of the incisors. Dental pulp is a loose CT which is kept in a pulp chamber with two root canals which have an opening to allow lymphatics, vessels, and nerves to enter. The purpose of pulp is to allow for sensation of sensitivity and pain as well as to carry vessels and lymphatics which nourish the tooth and protect the tooth from foreign infections. Anatomical Regions of Pulp - The coronal pulp occupies the crown and contains 6 surfaces: occlusal, mesial, distal, buccal, lingual, and floor. It contains pulp horns which correspond to the cusps of the crown. Often decreases in size with old age due to dentinogensis - The radicular pulp runs from the cervix to the apex via the root canal. Will also diminish with age due to dentinogenesis. Histological zones - Odontoblastic layer - Cell-free zone - Cell rich zone - Pulp core Cells in the Pulp - Odontoblasts in the odontoblastic layer; they make dentin - Fibroblasts which make the matrix, fibres, and ground substance of the pulp – found in the cellrich zone - Undifferentiated mesenchymal cells which may either turn into odontoblasts or fibroblasts. - T-Lymphocytes, macrophages, and dendritic antigen-presenting cells. Matrix - Made of Type I (60%) and Type III (reticular) collagen (40%). - Contains glycosaminoglycans: hyaluronic acid (60%), dermatan sulphate (20%), chondroitin sulphate (12%), and heparin sulphate (8%). - Contains proteoglycans and glycoproteins. Vascular Supply to the Tooth - Oxygenated blood supply of the arteries arises from the common carotid  external carotid  inferior and superior alveolar arteries  alveolar arteries  pulpal arterioles - 20mL-60mL/min to 100grams of teeth Innervation of the Teeth - Highly innervated by axons and nociceptors - The axons reach the odontoblasts or go to the cell-free zone Hydrodynamic Theory of Dentin Hypersensitivity The hydrodynamic theory of dentin hypersensitivity states that the change in dentinal fluid from pressure, heat, cold, and other stimuli will cause a depolarization of the neurons attached to the odontoblasts. When heat is detected by the fluid, it causes the dentinal tubules to expand thus causing the dentinal fluid to move down into the pulp. Cold causes the dentinal tubule to constrict thus causing the cold water to flow outwards. Age related changes to pulp - Pulp gets smaller with age due to creation of secondary dentin - Pulp becomes more fibrous - Pulp becomes less innervated with nerves and vessels - Pulp stones may occur. - “wear and tear”; as we age, the more our teeth have been through and the more trauma it has been affected with. Odontoblasts, thus, create a secondary dentin which projects the pulp and the roots of the tooth. Pulp Stones - Sites of calcification - They can be detected by radiographs; on the molars the bite-wings will aid in detecting pulp stones. - True denticles are pulp stones that are calcification of dentin with some tubules - False denticles are pulp stones of bone with some cells in it Clinical Considerations: - Dead pulp or necrosis to the pulp causes black or darkley shaded teeth - Progressiveness of the necrosis can affect the dentin which gives it that colour Dentin - - Dentin is located right under the crown It is pale yellow in colour and contributes to the color of teeth Contains parallel tubules known as dentinal tubules which contain dentinal fluid. Dentin, dentinal fluid, and the matrix of dentin are formed by the fixed cells known as odontoblasts. The odontoblasts on the inner aspect of dentin, right under the mineralised dentin. The dentinal tubules contains processes of odontoblasts. Dentin is stronger than bone and cementum, but softer than enamel. Dentin is not as hard or as stiff as enamel, but it does have greater compressive strength and can withstand something squishing against it; thus, dentin supports enam el because without dentin enamel would just be brittle and shatter. Dentin, by volume, is composed 70% of inorganic (calcium hydroxyapatite), 20% inorganic (collagen by 90% and proteoglycans), and 10% water Dentinal Tubules - Run parallel in a “sigmoidal” or curved way - As they reach the dentino-enamel, curvatures of the dentinal fluids become less pronounced - At the pulp-dentin junction, tubules are 2.5 micrometers wide, but at the dentino-enamel junction they become 1 micrometers wide. - Dentinal tubules can branch off, usually occurs profusely at the dentinoenamel junction - Between dentinal tubules are intertubular dentin (matrix) - In the dentinal tubules, peritubular dentin is laid down and begins to shrink the gap of the dentinal tubule. Peritubular dentin does not contain any collagen matrix and is more mineralised than intertbular dentin. - As we know, near the denitnoenamel junction, the intratubular dentin calcifies to make a much narrower tubule and the opposite for the pulp-dentin junction. If the intratubular dentin continues to calcify on both junctions the tubule will be very narrow and thus sensation of that tooth may be close to diminished. - Within the tubules are odontoblastic processes, afferent axons, and dentinal fluid. Different types of Dentin Primary dentin - Comprises the bulk of dentin o Mantle dentin which is slightly less mineralised and contains tubules; near the dentinoenamel junction o Circumpulpal dentin, as in the name, is dentin that surrounds the pulp chamber Secondary dentin - Develops after root formation is complete Tertiary dentin - Reparitive dentin; makes dentin after damage or trauma to cells. Dentinogenesis - In the pulp, specifically the cell-rich zone are undifferentiated mesenchymal cells - These cells go under mitotic activity and either become odontoblasts (make dentin) or ameloblasts (make enamel). - In early stages of dentinogensis, you will see von korff’s fibres which are type III collagen fibres that sit near the mantle dentin - Odontoblasts produce matrix vesicle which become foci for desposition of inorganic formation - Oral Mucosa - Lining of the mouth It is a wet, specialised area It protects the mouth from microorganisms and abrasions It secretes mucous and saliva by gland embedded in them It allows for sensation to temperature, pressure, taste, swallowing, gagging, and retching. Oral mucosa is an epithelium that contains an underlying connective tissue and lamina propria. Outer vestibule: Includes the cheeks and the lips Oral cavity proper: Gingiva, alveolar mucosa, tongue, roof which is comprised of the hard and soft palate and the floor which is comprised of the tongue and base of mouth. Types of Mucosa 1. Masticatory mucosa: 25%; gingiva, hard palate 2. Lining mucosa: 60%; comprises of alveolar mucosa, upper lip, buccal mucosa, labial mucosa, soft palate, ventral tongue. 3. Specialized mucosa: 15%; comprises of the dorsal tongue Components of Mucosa - Generally speaking, all mucosa has an epithelium layer of stratified squamous epithelium - They all contain a lamina propria within the connective tissue layer. The connective tissue layer in some mucosa may contain sebaceous glands with hair follicles; near the lip, cheeks, etc.. - Some mucosa contains a submucosal layer which contain minor salivary glands. Components of the gingival mucosa - Stratified squamous keratinising epithelium, including all masticatory mucosa - The lamina propria is directly attach to the alveolar bone: mucoperiosteum. All lining mucosa is stratified squamous non-keratinising epithelium. Within the epithelium you will find melanocytes which give mucosa their pink colour, Langerhans cells which are macrophages, and merkel cells which act as nerve cells. The Tongue - The tongue is a muscular organ in the mouth which contains many papillae on its dorsal surface. - These papillae contain many taste buds within them - There are 4 types of papillae: fungiform, circumvallate, foliate, and filiform. Filiform papillae - Do not contain any taste buds - Play a role in gripping food - Most abundant; found in the anterior 2/3 of the dorsal tongue. Fungiform papillae - Found within filiform - Found on the anterior aspect of dorsal tongue - May have taste buds Foliate papillae - Found on the lateral aspects of the tongue - Ususally not found in humans Circumvallate papillae - Contian taste buds - Larger - Found on the posterior aspect of the dorsal side of tongue Major Junctions of Oral Mucosa Dentinogingival Junction - Where the gingiva and the tooth meet - The gingiva that attaches to the tooth has some parts to it. The main part that is attached to the enamel/cementum of the tooth is called the junctional epithelium - This junctional epithelium contains the lamina propria and hemidesmosomes to attach itself to the basal lamina and to the tooth itself. - When a dentist is preforming an oral examination, they will usually use their probe to measure how deep your gingival sulcus is. In a healthy person, 0.5-3mm is a safe gingival sulcus depth; anything higher than these numbers is considered pathological and that is why it is so important to floss. - The dentinogingival junction serves a great purpose to hold the tooth in place and keep it from falling out of its’ socket. Mucogingival Junction - Junction between the alveolar mucosa and the gingiva. - The alveolar mucosa is non-keratinising while the gingiva is keratinising. - Clinically, the alveolar mucosa looks like a darker pink while the gingiva looks lighter pink. - Alveolar mucosa is made of loose connective tissue with lamina propria and many elstic fibres - Gingival mucosa contains lamina propria and coarse collagen fibres that attach to the periosteum of the alveolar bone. Mucocutaneous junction - Where oral mucosa meets with skin - May contain hair follicles and sebaceous glands - The vermillion are the lips; keratinising epithelium with thin layer of epithelium but many capillary loops in surface of connective tissue - Contains no salivary glands Salivary Glands - Exocrine glands - Secrete substances into the mouth via ducts - 3 major glands - Many minor salivary glands that contribute to 10% of salivary outflow Parotid Gland - Gland found near the muscles of the face by the ear - Duct is located in the alveolar mucosa above the second molar on the maxillary level. - Composed strictly of serous acinar glands - Secrete saliva with many enzymes such as hydrolase which aid with the breakdown of food - Surrounding connective tissue contains many plasma cells which secrete antibodies with the saliva to fight off foreign substances Submandibular salivary gland - Made of tubular-acinar glands with both serous and mucous cells - 90% is serous cells; 10% is mucousa cells with serous deminlunues - Serous cells secrete amylase. - Serous Demilune screte lysozyme that hydrolyses bacterial walls. Sublingual salivary gland - Made of tubular-acinar gland with both serous and mucosa cells - Predomintly mucous cells - Serous cells are strictly present as deminlunes Taste How we perceive smell - In infancy, we can interpret right away what taste good and what tastes bad - If something is sweet and nice, infants tend to smile or chap their lips - If something is bitter and bad, infants tend to frown or grimace - Taste and smell cells are known as chemoreceptors – they detect senses by chemicals that cause a change. - Taste is 75% smell Why do we taste? - Taste is something that allows us and our bodies to become conscious of what we are eating and if it is potentially dangerous to our bodies. - Usually eating something good means it is good for us and vise-versa, but this is not always the case - Some things that taste and smell good tend to be poisonous to our bodies Smell - Odours and gasses are inhaled by the nose or mouth and are collected by olfactory cells. - These olfactory cells call up memories in the brain, specifically the amygdala, and determine what is good and what is bad - Females have a keener sense of smell - Both nostrils can perceive slightly different smells – aids with precision - Loss of smell is known as anosmia Taste - Perceived by taste buds in our papillae on our tongue, except for filiform papillae - 75% smell is taste - 5 different senses of taste Types of senses for taste: - Sweet: Triggered by sugars such as fructose and glucose - Salty: Sensation to salts and foods with Na - Umami: Triggered by glutamate or monosodium glutamate. - Bitter: Triggered by alkaloids; our tastebuds are the most sensitive to bitter foods. - Sour: Triggered by accumulation of H+ ions; low pH Lingual Papillae - Majority of the taste buds are found within the lingual papillae. - Taste bud are also found on the palate, pharynx, and epiglotÝs. - Filiform papillae are papillae on the anterior 2/3 of the tongue. They do not contain any taste buds, rather play a role in gripping food - Fungiform papillae are the second most abundant papillae in the tongue and are found amongst the fungiform papillae. They contain taste buds on the superior aspect of it - Foliate papillae are found on the lateral aspects of the tongue. Taste buds are found on the lateral aspect of the papilla. - Circumvallate papillae are found on the posterior aspect of the dorsal tongue. They are the largest and most rounded. Taste buds are found on the lateral aspect of the papilla. Taste Buds and their Anatomy The taste bud is composed of epithelium and many cells within it. Type I cell are supporting cells; Type II are gustatory cells for sweet, umami, bitter and sometimes salty; Type III is for sour; Type IV are basal cells that replenish and change the gustatory cells every 2 weeks. Taste chemicals cause membrane changes to the gustatory cells which cause an action potential to sensory nerves: cranial nerves (7- facial; 9 – glossopharyngeal; 10 – vague nerve) Taste Transduction - Umami, sweet, and bitter taste intiate G-Couples protein - Molecules such as glutamate and monosodium glutamate will attach to the T1R1 and T1R3 recepots of an umami gustatory cell which will cause G-protein activation and increase of intracellular calcium ions to cause depolarization. - Molecules such as glucose will attach to T1R2 and T1R3 receptors and cause a membrane change which will activtate G-proteins and increase intracellular calcium to cause depolarization. - Molecules such as alkaloid metal will bind to TR2 proteins and cause a membrane change which will activtate G-proteins and increase intracellular calcium to cause depolarization. - Salty ions such as Na+ will enter via sodium ion channels to increase intracellular Ca2+. Neural Pathways for Taste - Anterior 2/3 is supplied by CNVII (facial nerve) - Posterior 1/3 is supplied by CNIX (glossopharyngeal nerve) - Pharynx, larynx, epiglotÝs, and palate are supplied by CNX (vagus nerve) - These nerves join together at the brain stem. As they move further along the brain they join with the nerves for smell to detect flavour and go towards the temporal lobe which is associated with memories; thus, smell and taste can bring up memories. Taste Disturbances – Clinical highlights - Chlorohexidine: Found in moth wash; persistent taste of bitterness; loss of salty taste - Sodium lauryl sulphate: detergent aspect of toothpaste; loss of sweet and salty taste - Doxycycline: Anosmia - Tetracycline: Metallic taste - Metronidazol: Taste disturbance. Tooth Morphology Every tooth has different characteristics that allow it to function properly and allow us to eat, shred, and tear food. Incisors The incisors play a role in shearing food, or breaking off food. Maxillary Central Incisor Looking at the picture, from the palatal view, you can see the mesial and distal marginal ridges surrounding the lingual fossa. Inferior to the fossa is the cingulum. From the labial view, the cutting edge is known as the labioincisal edge. You can also see that the on the mesial end of the labial incisal edge is much sharper than the distal, as this tooth is an example of an maxillary left central incisor. The tooth is convex on the labial surface and concave on the palatal surface. C MMR DMR LF LIE Maxillary Lateral Incisor Similar in looks to the maxillary central incisor. Rounded disto-incisal angle while the mesio-incisal edge is sharp, but it is not as evident as it is in the maxillary central incisor. This tooth’s root is much more longer and less proportionate to the size of the crown than the central incisor and the root curves towards the distal end. Mandibular Central Incisor Function: Cutting food Overall appearance: Small, sharp incisive edge. Lingual: Relatively smooth and has poorly developed cingulum and marginal ridges. Incisal: Newly erupted has 3 mamelons, but becomes sharp overtime. Mesial: Distal: Labial: Comvex Root: Same size root as maxillary central incisor, but apex is more blunt. Mesio-distal compression of the root Function: Cutting food Lingual: Undeveloped marginal ridges, but more developed than mandibular central incisor. Incisal: Newly erupted has 3 mamelons then becomes sharp; slightly longer incisive edge than mandibular central incsior. Sharper mesio-incisal edge than disto-incisal edge. Mesial: Mesial side of crown is slightly longer. Distal: Similar in shape to mesial, but mesial crown is slightly longer. Labial: Convex Root: 14mm root; longer than central mandibular incisor Canines Transitional teeth between the incisors and the pre-molars. Only tooth in the dentition with one cusp. Tearing food is their function. Maxillary Canine Palatal: Bulky, well developed cingulum Incisal: One sharply-pointed cusp. Mesial: Less deeper slope of cusp than distal Distal: Deeper slope of cusp Labial: Convex Root: Long root Mandibular Canine Lingual: Concave; less developed marginal ridges and cingulum in comparison to maxillary. Incisal: Single, pointed cusp; not as sharp as maxillary. Mesial: Flattened root with slight groove Distal: Flattened root with slight groove Labial: Convex Root: Long strong root; can be bifid in some cases. The crown of the mandibular canine is narrower which makes it look larger in proportion Premolars Play roles in tearing food. Bicuspid. First Maxillary Premolar Occlusal fissure which empahsies the cusps on the buccal and palatal ends. Contains 2 roots; buccal and palatal. The buccal cusp is larger than the palatal cusp. Second Maxillary Premolar Occlusal fissure which emphasies two cusps: palatal and buccal. Both cusps are similar in size. Contains one root. First Mandibular Premolar Contains a mesio-distal occlusal fissure. 2 cusps, the buccal one is larger. Single conical root. Second Mandibular Premolar Single conical root. Occlusal surface contains a mesiodistal fissure. Seperates the two cusps which are the buccal and lingual cusp. The buccal cusp is larger and the lingual cusp can be divided into 2 cusps: mesiolingual and distolingual cusps. First, second, and third maxillary molars - All 3 have 3 roots (2 buccal and 1 palatal) - On the first molar, the palatl is longer and stronger. - The 2 buccal roots are usually flattened mesiodistally. - St molar has 4 cusps: 60% of these molars have an accessory cusplet known as tubercle of carabelli. - 2nd molar has 3 roots as well, but tend to be shorter and less divergent - 3rd molar’s roots may be fused and is commonly missing cogentially. Mandibular Molars The first mandibular permanent molar contains 5 cusps and the fissure follows the dyropithecus. It also contains 2 cusps – mesial and distal cusp - The second mandibular molar contains 4 cusps with a crossshaped fissure. Contians a mesial and distal root as well. - Third molar can have 4 or 5 cusps with an irregular shaped fissure. Contains 2 roots, mesial and distal, that are fused together. Importance of: 1. Contact points: The mesial aspect of one tooth directly leans itself to the distal aspect of the tooth in front of it; this is due to the natural tendency of mesial drift. When someone even loses a tooth, the adjacent tooth behind it will naturally put itself in place of where that missing tooth is and will cause over-stress of the TMJ and bone loss problems. That is why it is important that missing teeth are always treated with either prosthetics, partial dentures, or implants. 2. Marginal ridges: Marginal ridges are slight elevations that keep food on the occlusal aspect of the tooth for chewing. Not resorting the marginal ridges may lead to food entering the gingival pickets and causing gingivitis. 3. Curvatures of cheek teeth?