 Hello everyone, welcome back to another session on dentistry and more today's topic is alveolar bone. So alveolar bone is one of the component of pyridontism. So pyridontism consists of two soft tissues and two heart tissues. So junjewa and pyridontal ligament are the soft tissues whereas the cement and alveolar bone are the heart tissues. So we finished junjewa, pyridontal ligament, cement and now we are moving on to alveolar bone. So I hope you understood all the three concepts junjewa, cement and pyridontal ligament. So understanding pyridontium and its component requires a thorough knowledge of tooth formation and its stages. So bud stage, cap stage, bell stage, thorough knowledge would help you to understand all the other chapters and other concepts so easily. If you have a proper knowledge about the basic concepts, it will be very difficult for you to understand the further topics because all are interconnected because the tooth formation happens altogether in amyl dentine, pulp, root, pyridontal ligament, cement and junjewa. So all are forming as a unit. So you just cannot skip one unit and learn the other units. So you have to learn everything altogether. For that you need to have a very good knowledge about the beginning of tooth, bud, bell and cap stages and all the layers and the other components. So it will be very easy to understand all the remaining topics in oral cavity. So let's see the details of alveolar bone. So this session is about its composition, its classification and development. Alveolar bone is by definition part of the portion of maxillan mandible that forms and supports the tooth socket. So entire maxillan mandible we need to think about a portion which supports and forms the tooth socket which supports the tooth roots or tooth so that a smaller part or comparatively smaller part of maxillan mandible that supports the root is alveolar bone. So it has a role in rapid remodeling like during the tooth eruption and functional demands it continuously remodeled and it acts as an attachment apparatus for cement and pyridontal membranes and alveolar bone. So it has got various functions, functions it provides attachment to the pyridontal ligament, it absorbs the occlusal pressure, it gives attachment to muscles, it provides framework for the marrow, it is a reservoir for ions especially calcium and it house the roots of tooth which is achieved by the insertion of sharpies fibres into alveolar bone proper. So there are various functions, now we are seeing about the composition of alveolar bone. So alveolar bone is composed of inorganic and organic matter and two third of total is inorganic matter and the remaining one third is organic matter. So inorganic matter includes hydroxyapatite crystals and minerals such as calcium, phosphorus, carbonate, citrate, hydroxyl ions, magnesium, sodium, potassium, fluoride and very smaller quantity. Whereas inorganic matter it consists of both collagen and non-collagenous proteins. Percentage is non-collagenous protein such as osteocalcin, osteonectin, silo protein, phosphor protein and proteoglycans. So that is about composition of alveolar bone. And now we move on to the most critical part that is development. So alveolar process consists of bone which is formed both by cells from dental follicle that is alveolar bone proper and cells which are independent of tooth development that is brachial or mandibular arch because maxilla and mandible develops from first brachial arch or which is also known as mandibular arch. The maxilla forms within the maxillary process and mandible forms within the fused mandibular process of mandibular arch. And both jaw bones start as small centers of intramembranous ossification around stromodium. So it is formed both by cells from the dental follicle, from dental follicle what forms alveolar bone proper and maxilla and mandible forms from the cells which is independent of tooth development that is first brachial or mandibular arch. Now let's see step by step process of alveolar bone formation. First what happens maxilla and mandible develops intramembranously and at 8 week of utero what happens alveolar process develops from the dental follicle during tooth eruption. So maxilla and mandible already is forming intramembranously and around 8 week in utero what happens the alveolar process develops from dental follicle. This is intramembranous development and dental follicle give rise to alveolar process that happens during the tooth eruption. So next in bell stage the developing bone becomes closely related and the size of alveolar is dependent on the size of the growing tooth germ. So it is always closely related the size of tooth germ and the alveolar bone. An alveolar bone it develops in a resorption deposition fashion it resorps at the inner wall and it gets deposited on the outer wall so it grows. So these developing teeth which lie in a trough of bone which is known as tooth crypt. So after that what happens these teeth which separated from each other by the development of interdental septa. So interdental septa forms and these teeth are separated. And then with the onset of root formation the interradicular bone develops in multi-rooter teeth. So we have seen interdental septum then there will be interradicular bone formation as root formation happens between the two roots of multi-rooter teeth. So whereas in case of deciduous teeth when a deciduous tooth shed its alveolar bone is automatically resorbs. So after that the alveolar process gradually getting incorporated into maxilla or mandibular body. Though it has separate origin finally it will be a one single bone. So permanent tooth moves into place developing its own alveolar bone from its own follicle. So the dental follicle give rise to pedodontal ligament, cementum and alveolar bone. So that's about development. So maxilla mandible forms through intramembraneous ossification in 8th week of utero alveolar process develops from dental follicle and it becomes closely related in bell stage. So it depends on the tooth germ size and resorption happens in a wall deposition on outer wall and it grows. And these tooth lie in a trough of bone which is known as tooth crypt and these tooth separated by interdental septum and interradicular bone which separates the different roots of multi-rooter tooth and the deciduous tooth alveolar bone automatically resorbs and it slowly getting incorporated into the body of maxilla and mandible and will be a single bone. Now let's move on to the classification. We have many classification in alveolar bone. The one is based on the functional adaptation. So according to functional adaptation it can be classified as alveolar bone proper and supporting alveolar bone. So alveolar bone proper is just adjacent to the tooth root and the remaining part is supporting alveolar bone. And another classification is based on the histological characteristics. It can be divided into mature and immature bone. Mature again into compact bone and canceless bone. Immature is woven bone. This is very important. Histological classification mature and immature. Mature into compact and canceless bone and immature into woven bone. Compact means it is very densely compacted. Cancelous is not very densely compacted. Waven is a immature bone. And ultimately we can classify it is based on the gross morphology. So gross morphology we have basically only two types. One is basal bone and alveolar process. So alveolar process again it will be classified as alveolar bone proper, inner and outer cortical plates, trabecular bone, interdental septum and interradicular septum. So alveolar bone proper, inner and outer cortical plates, trabecular bone, interdental septum and interradicular septum. The alveolar bone proper which is again divided into bundle bone and lamellar bone. This is based on the gross morphology. This is based on the histology. This is functional adaptation. So let's see one by one. So first one is alveolar bone proper. So alveolar bone proper is a thin layer of compact bone. So before that we need to study what is compact bone and what is cancelous bone. And this is a alveolar bone. This part up to the root tip arbitrarily we can say that it is alveolar process and the remaining bone is a basal bone. So up to the root tip. There is an arbitrary point alveolar process and basal bone. So when we take a longitudinal section we get two layers of bone. The outer compact bone which is in pink color and the inner cancelous or spongy bone. Now we will start with alveolar bone proper. So alveolar bone proper is a thin layer of compact bone. So this is a compact bone, the pink shaded and this black inner covering of the compact bone is known as alveolar bone proper. So it is continuous with the cortical plates and it forms the tooth socket. So it forms the tooth socket. So it is continuous with cortical plates and it forms the tooth socket. So it will be like this. So that is alveolar bone proper. It surrounds the root of the teeth and gives attachment to the principal fibres of periodontal ligament. So there will be principal fibres of periodontal ligament attached to the inner layer of cortical bone. So this is vascular canals and it is a double fibreler orientation. So this is very important in radiography because cribriform plate is anatomical landmark and lamina dura which we seen in radiograph which is covering the root is a radiographical term and we also call it as bundle bone. So bundle bone is a part of alveolar bone proper and it has lamellar portion also. So it is known as cribriform plate, lamina dura, bundle bone and alveolar bone proper. Lamina dura is a radiographic term, cribriform plate is anatomical term and bundle bone is a morphological and alveolar bone also morphological term. So it is around the teeth actually. Now we have inner and outer cortical plates. So alveolar process is continuous with the basal bone of maxilla and mandible. So this is the basal bone. So alveolar process is continuous with the basal bone. So arbitrarily as I mentioned the root tip keeps the alveolar process away from basal bone but it is a continuous we can keep an arbitrary point and we can divide the entire one into alveolar process and basal bone and alveolar bone proper is known as bundle bone as numerous bundles of sharpies fibers pass into it from the periodontal ligament okay. So that is why it is known as bundle bone lamina dura is because of its appearance it is a radio opaque area and cribriform plate because it has numerous sieve like appearance the vascular channels. So the alveolar bone proper has bundle bone lamina dura and cribriform plate synonyms. So it appears as a radio opaque or white line radiograph which breaks in continuity and if it is break in continuity of lamina dura at proximal aspect of crust of inter dental septum this is a inter dental septum and at the crust of inter dental septum if the breakages of lamina dura is visible then it is considered as the earliest radiographic change in periodontitis. So if the inter dental septum if the covering that is a lamina dura is not continuous then we can say that that part of bone is associated with some of the inflammatory process and which is indicating of periodontal disease at the earlier stage. Now we will see the cancerless bone okay. Cancerless bone is also known as spongy bone which is anatomic nerve, trabecular bone which is a radiographic nerve and cancerless bone is a historical name okay. So spongy bone, cancerless bone and trabecular bone are same. Cribriform plate, lamina dura, bundle bone and alveolar bone are same. So spongy bone or cancerless bone or trabecular bone which is a presence of trabeculae including irregular marrow spaces lined with a layer of thin flattened endosteal cells. This metric consists of irregularly arranged lamellae separated by incremental and resorption lines. So this is a lamellar part okay. So the alveolar bone proper has bundle bone and lamellar bone. So matrix consists of irregular arranged lamellae and it is got basically two types type 1 and type 2. Type 1 the inter dental and inter radicular trabeculae are regular and horizontal in a ladder like arrangement whereas a type 2 shows irregular arranged delicate inter dental and inter radicular pattern. So inter dental septa or inter dental bone is between the roots of two teeth whereas inter radicular is between the roots of multi-rooted teeth okay. This is inter dental between the teeth this is inter radicular between the roots. So the cortical bone and spongy bone. So this is the cortical bone which is compact bone and the spongy bone inside okay. So cortical bone is another name of compact bone. So cortical bone is around see 85 percentage. The spongy bone is 15 percentage. Cortical bone is having less turnover than spongy. This is having high turnover and remodeling is around 3 percentage in cortical or compact bone and this is remodeled at 25 percentage and spongy bone is mainly of metabolic function. This is of mechanical and protective role. So the layer of compact bone or cortical plate as known as alveolar bone okay and then inside this is spongy bone. This is alveolar process and this part is basal bone. Now we have inter dental septum. Inter dental septum is a bony partition that separates the adjacent alveoli. Coronally septa is thin and consists of only fused inner cortical plates. Coronally it will be thin and mesodistral angulation of mesodistral angulation of inter dental septum is parallel to the line drawn between CEJ and approximating teeth and if inter dental septum is narrow the septum may consist only cribriform plate. If the roots are too close together an irregular window can appear in the bone between the adjacent tooth. So it is a alveolar bone which is present between the teeth that is inter dental septum and the shape of inter dental bone is a function of tooth form and embrasure width. The more taper the tooth the more pyramidal in the bony form. The wider the embrasure more flattened the inter dental bone will be. Alveolar crest is a tip of inter dental bone where the inner and outer cortical plate meets the margin will be thin and knife edged in vestibular surfaces of anterior and rounded posterior teeth. Most prominent border of inter dental septum. Okay so this is a crest of alveolar outer and outer and inner cortical plates. This is a crest of inter dental septum in one way. Inter radical septum is a bone between the roots of multi-rooted teeth. So basal bone, basal bone it is the auspicious tissue of the mandible and maxilla except the alveolar process. Okay so alveolar process is up to the root and it is a auspicious tissue that mandible and maxilla without alveolar process. So part of mandible and maxilla without alveolar process is basal bone. So this is a alveolar bone. This is a basal bone. Okay and anatomically we cannot say that there is a distinct boundary that exists between maxilla mandible alveolar process and basal bone. This is just an arbitrary line. So we have covered our classification and the formation of bone, the process of alveolar bone formation and classification in detail and about composition. Now the second part of alveolar bone will be covering the histology that is various cells and matrix components. So I'll come up with the second part the cells of alveolar bone basically the histology.