 Hello everyone, welcome back to another session in Dentistry and what today's topic is Dental Pulp. So we finished our majority of the topics that is enamel, dentine and the pyridontium which includes cementum, alveolar bond, pyridontal ligament and ginjeba. So the last topic is Dental Pulp in the tooth related structures. So let's get into details of dental pulp which is a mesenchymal connective tissue. So as I mentioned it is a soft mesenchymal connective tissue which occupies the pulp cavity in the central part of the tooth and it is a special organ because of the unique environment and which is surrounded by a rigid wall that is dentine which is unable to expand in response to injury as a part of inflammatory process. That is why we are having severe pain when we are having caries or when there is an infection and the pulp or the caries are invading pulp. So the pulp tissue is susceptible to change in pressure which affects the pain threshold and pulp is a simple connective tissue. It is peripherally laid by ordentive blast because it is outlined as dentine. Secondary dentine deposited gradually that is a aging process which reduces the blood supply and making the tooth resistant to trauma and infection because it has defensive cell. On an oral cavity we have 52 pulp organs that is 32 of permanent teeth and 20 of primary teeth and total volume will be 0.38cc and the mean volume is 0.02. So each of these organs which takes the tooth which is occurring within. So if it is a central incisor it will be of the shape of central incisor if it is smaller it will be of molars. So it takes the shape of the tooth which is present within. So the development we have discussed in detail in our tooth bud formation to bud cap bulb stage formation. So it starts from dental papilla at 8th week of intra uterine life. So there will be a condensation of mason game under the enamel organ which is known as dental papilla. So this enamel organ enlarge and enclose the dental papilla in the central region. So dental papilla which controls morphology and type of tooth to be formed. So there will be high vascularity and high proliferation of dental papilla which later develops into pulp. So basically we have two types of pulp that is coronal pulp which is present in the crown portion and radical pulp which is in the root portion. So coronal pulp is located within the crown of the tooth and radical pulp is located within the root. The coronal pulp it is occupying the pulp chamber of the crown of tooth. In young teeth it resembles the shape of outer dentine. So it has six regions like occlusion, mesial, distal, buccal and lingual and there will be a floor of the pulp. So pulp horns are projected into cusp. So there will be a pulp horns which is projected into the cusp. So this pulp constricts at the cervical region where it continues as radical pulp. So at this border where the coronal and radical pulp meets there will be a constriction and it continues as radical pulp. So whereas a radical pulp which occupies the pulp canals and root of the tooth in the anterior tooth it is single and in posterior tooth it is multiple because it has multiple roots. So the radical portion of the pulp is continuous with the periapical tissues with the apical foramen. So there will be apical foramen here. So it will be continuous to the periapical tissues through apical foramen. So apical foramen will be here. So it will be continuous with the periapical tissues. So any infection is there which will be spread to periapical region. So as age advances width of the radical pulp will be reduced and so the apical foramen. The apical foramen which is the pulp cavity terminates at root apex at a small opening which is known as apical foramen. So radical pulp continues with connected tissue of peridontia with this foramen and diameter is 0.4 in maxilla and 0.3 mm in mandible. So wide opening during development of root which will be constricted once the dentain and cement in the position happens. So this opening sometimes will be found on the lateral side of apex. So sometimes it will be here lateral side. So there may be two or three foramina split by cementum which is known as apical delta. So if you have more than one apical foramen split by cementum and dentain which is known as apical delta. So accessory canals. So it is from the lateral side of radical pulp into peridontal tissues not just the root tip. So they are numerous in the apical third. So it will be numerous in the apical third and formed due to the premature loss of hard wicks epithelial root sheath. So you remember what is hard wicks epithelial root sheath which is a condensation of outer and inner enamel epithelium which helps in formation of fruit and which will be fragmented and it will become epithelial rest of molasses. So that is accessory canals. So now let us move on to the important part that is the zones of pulp. So histologically it has four zones that is autentoblast, cell free zone which is also known as wheel zone, cell rich zone and pulp proper. So autentoblast layer which is this is autentoblast layer which is near to the dentine or exactly we can say it is near to pre-dentine which is a first form dentine and the cell bodies in the pulp and cell process in the dentinal tubules. The cell body is in the pulp and the process in the dentine whereas a cell free zone which is very important which is also known as wheel zone which is 40 micron wide and relatively free of cell. You cannot see any cells here. We have cells which is on a cell rich zone. So cell free zone which is traversed by you can see the blood vessels, nerves and cytoplasmic process are going. So there will be nerves, blood vessels and cytoplasmic process but there will not be any cells. So as you can see this zone is below the autentoblast layer. Now we have the cell rich zone which is present in the sub-autentoblast layer. So the cell rich zone which has got more proportions of fibroblast and undifferentiated mesenchymal cells which has macrophages, dendritic cells, lymphocytes which is formed due to the migration of cells from pulp proper. So pulp proper is here and mitosis is seen when dead autentoblasts are replaced and also contain young collagen fibres during early dentinogenesis. There is a pulp core which is the central region of pulp which contains major blood vessel and the nerves of pulp which has pulp cells and fibroblast. So the various cells of pulp are autentoblast, fibroblast and differentiated cells and different cells. The autentoblasts are peripheral areas which is seen in the peripheral areas of pulp where the autentoblast reside which is termed as autentogenic zone where it is producing dentin. So that is autentoblast which has large process extending into dentin. The number of autentoblasts corresponds to the number of dentinal tubules and the autentoblast in the crown region will be larger than the root areas and the shape of autentoblast also reflects the functional activity of the cell. So there will be active phase and non-active phase, active phase cells show increase in etoplasmic reticulum, Golgi apparatus and secretory vesicles whereas a non-active phase it will be condensed. So it has a condensed cytoplasm with a decreased number of entoplasmic reticulum. And we have next is functions of autentoblasts which is nothing but synthesis of organic matrix, collagenous substance like sila protein, phosphor protein and intracellular accumulation of calcium, degradation of organic matter. So next one is fibroblast which is in greater number in the pulp which is to form, maintain the matrix that consists of collagen fibers and ground substances which is a stellate shaped which is having extensive processes. And the next one is undifferentiated mesenchyme cells. These makes mesenchyme cells which are distributed throughout the pulp, so frequently around the peri vascular area. So they are polyhydral shape with peripheral process, we cannot differentiate from fibroblast. So they differentiate into odentoblast, fibroblast or macrophages. And the last one is defensels, we know the defensels which are macrophages, mast cell, plasma cell, lymphocyte, neutrophils, isnofil and macrophages, all these defensels we have learned in pathology regarding the macrophage, mast cell, its appearance, plasma cell, lymphocyte and isnofil. So extracellular matrix we have connected tissue which has collagen elastin and fibronectin, ground substances are proteoglycan, glycosaminoglycans and other membranes. So collagen fibers are the extracellular structural proteins which consists major part of connected tissue which is, these collagen fibers do not contribute to dentine matrix formation. So after root completion and pulp matures the bundles of collagen fibers increase in number. So the few types like type 1, type 3, type 4, type 6 and type 5. Elastic fibers are which has ability to expand and elastic fibers, ability to expand and contract like a rubber band that is why this name it got, it got this elastic fibers are first formed in bundles of thin micro filaments called oxytalin fibers. So all these we have covered in pedodontal ligament. Let us apply to pulp is very vital which has many arteries running in our head and in our neck region like external carotid to superior inferior alveolar arteries. So major arteries we know the arteries are dental branches, mental branches, insulci branches, intraorbital artery, posterior superior alveolar artery and also lymphatic drainage we have submaxillary gland, submental gland and other cervical lymph nodes which are drains into superficial and deep cervical nodes. Nerve supply are like basically trigeminal nerves supply the head and neck region. The maxillary nerve and mandibular nerve it has anterior superior alveolar nerve, intraorbital nerve, posterior superior alveolar nerve and lingual nerve and inferior alveolar nerve. And in nerve fibers we have a peculiar appearance that is now plexus of Resco which is now enters through the apical foramen as myelinated nerve fibers and they branch to form subordentoblastic nerve plexus of Resco which is separated from the ordentoblast by a cell free zone of wheel. So here it is having the nerve plexus of Resco which is entering through the apical foramen and it is branches out and it is present in the subordentoblastic region between cell free zone and ordentoblastic. So next is we have age changes. Age changes are the size of pulp, apical foramen, cellular elements, blood vessels which will be decreased as age goes and we have very important session which is pulp calcification. So we have localized calcification and diffuse calcification. Localized is known as pulp stone which could be true dendicle and false dendicle and also we can have diffuse calcification. The true dendicle that is a localized pulp stone which is rare and small in size which is found near the apical foramen which consists of irregular dentin and traces of dentin altibules and few ordentoblast and remnants of epithelial root sheath which invade the pulp tissue causing the pulp to form irregular type of dentin which is becoming pulp stone. So it is a part of dentin. So dentin is present within the pulp is known as true dendicle which is irregular dentin and formed by the epithelial root sheath. Whereas a false dentin, denticles which are evidence of distrofic calcification of pulp tissue which does not contain any dentin altibules only true denticles has dentin altibules. So these false denticles are formed of degenerated cells or areas of hemorrhage which act as a central focus of this calcification and our doses of vitamin D may favor the formation of these pulp stones. So pulp stones are classified according to their location like free attached and embedded so free is it is free in the pulp attached is attached to the dentin and embedded is which is embedded within the dentinal walls and close proximity of pulp stone to blood vessels may cause atrophy of it and the second type is diffuse pulp calcification which is commonly occurs on the top of hyaline degeneration in the root canal and not common in pulp chamber they are irregular calcification deposition in the pulp tissue following the course of blood vessels and advancing age favors their development diffuse calcification. And the perisites it is a very important short note perisite which are actually capillary associated fibroblast which is suggested as progenitor cells for replacement of odentoblast so perisites are progenitor cells for replacement of odentoblast which are capillary associated fibroblast so perisites which are around the endothelial lining and which is basically involved in the production of odentoblast. The last part is functions of pulp there are lots of function because it is a a blade rich area which has nerves which has undifferentiated cells which is having different cells so there are lots of function for pulp one is in so an inductive function so dental papilla induces enamel organ formation and also determines the morphology of tooth the second one is formative function pulp organ produces dentin odentoblast develops organic matrix and function so that is a formative function reparative means the formation of highly mineralized reparative dentin at the site of injury so we have learned the types of dentin how the reparative dentin is formed so it is the cells are coming from the pulp issues. So, defensive would has defensive cell we have seen the defensive cells of pulp macrophages histiocytes plasma cells all are involved in defensive action and protective any environmental irritant stimuli always elicit pain as a response that is a protective function and nutritive the pulp vasculature it is giving an nourishment to the odentoblast continuously and also to the secondary dentin so that's all about pulp so dental pulp is a small chapter compared to our enamel dentin and other pedontial ligament so we finished enamel dentin pulp and pedodontium pedodontium is having four sections that is two heart tissues which is cementum and alveolar bone and two soft tissues which is genjeva and pedodontal ligament so next we have another topic in dental histology which we will be dealing about the salivary glands so to make sure that you learn the basics first then you go to the other chapters so the tooth formation should be very thorough when you are trying to learn the concept of other structures such as enamel dentin pulp so because formation and the other parts are interconnected so it is very easy when you learn the basics in detail so I will come up with a new session and end this demo thank you