The periodontium develops from neural crest cells that migrate to form dental tissues. The dental lamina forms and invaginates, leading to tooth bud development through the bud, cap, and bell stages. Mesenchymal cells aggregate to form the dental papilla and follicle. The follicle gives rise to cementum, periodontal ligament, and alveolar bone. Cementum forms on the root surface in two stages - primary acellular cementum deposited before eruption, and secondary cellular cementum deposited after eruption. The periodontal ligament develops prior to eruption from the dental follicle.
This document discusses the development of the periodontium, which includes the cementum, periodontal ligament, alveolar bone, and gingiva. It describes how the tooth germ develops from the enamel organ and dental papilla through stages of growth. Root formation is induced by Hertwig's epithelial root sheath, which regulates the development of cementum, periodontal ligament, and alveolar bone through cellular differentiation and protein signaling. The periodontium develops through reciprocal interactions between the enamel organ and dental follicle mesenchyme.
This document provides information about pain and its relation to periodontics. It begins with definitions of pain, including the International Association for the Study of Pain's definition. It then discusses the historical understanding of pain, classifications of pain, and theories of pain mechanisms. The document outlines the nervous system components involved in pain perception and pathways. It discusses assessment of pain and specific types of periodontal and gingival pain, including their characteristics and diagnostic criteria. Overall, the document provides a comprehensive overview of the physiology and experience of pain as it relates to periodontal conditions and treatments.
The document summarizes the development of the periodontium. It discusses how the dental follicle derived from neural crest cells gives rise to cementum, periodontal ligament fibroblasts, and alveolar bone. It also describes the development of the individual tissues - how cementum and periodontal ligament fibers form along the developing root surface, how the gingiva and junctional epithelium develop during tooth eruption, and how alveolar bone develops from the dental follicle to support the tooth socket. The periodontium develops as an integrated unit with interactions between tissues to provide structural support for teeth.
Blood supply,nerve supply and lymphatic drainage of the periodontium finalDr. Neha Pritam
The document discusses the blood supply, nerve supply, and lymphatic drainage of the periodontium. It states that the periodontium receives its blood supply from branches of the internal maxillary artery and its lymphatic drainage involves drainage to local lymph nodes. It also describes the rich nerve supply to the periodontium derived from the trigeminal nerve and its branches. Changes in microcirculation and lymphangiogenesis occur in the periodontium during periodontal disease.
This document summarizes a presentation on the periodontal ligament given by Dr. Abhishek Gakhar. It discusses the structure, development, constituents including cells, fibers and blood/nerve supply of the periodontal ligament. The functions of the periodontal ligament and its clinical correlations are also reviewed. Diagrams illustrate the fiber groups and cells found in the periodontal ligament.
Wound healing [including healing after periodontal therapy]Jignesh Patel
The document discusses wound healing and periodontal wound healing in particular. It describes the processes of regeneration and repair. Regeneration involves renewal of tissues through growth of same tissue type, while repair involves replacement of tissues through scar formation. The molecular biology of wound healing is explained, including roles of fibrin clot, growth factors, matrix degradation and connective tissue formation. Healing by primary and secondary intention is also defined. Healing processes following various periodontal procedures like scaling, root planing, flap surgery and implant placement are outlined. Factors influencing wound healing and potential complications are briefly mentioned.
alveolar bone in health with microscopic features and details about bone formation, resorption also includes bone remodelling and changes after extraction
This document discusses the development of the periodontium, which includes the cementum, periodontal ligament, alveolar bone, and gingiva. It describes how the tooth germ develops from the enamel organ and dental papilla through stages of growth. Root formation is induced by Hertwig's epithelial root sheath, which regulates the development of cementum, periodontal ligament, and alveolar bone through cellular differentiation and protein signaling. The periodontium develops through reciprocal interactions between the enamel organ and dental follicle mesenchyme.
This document provides information about pain and its relation to periodontics. It begins with definitions of pain, including the International Association for the Study of Pain's definition. It then discusses the historical understanding of pain, classifications of pain, and theories of pain mechanisms. The document outlines the nervous system components involved in pain perception and pathways. It discusses assessment of pain and specific types of periodontal and gingival pain, including their characteristics and diagnostic criteria. Overall, the document provides a comprehensive overview of the physiology and experience of pain as it relates to periodontal conditions and treatments.
The document summarizes the development of the periodontium. It discusses how the dental follicle derived from neural crest cells gives rise to cementum, periodontal ligament fibroblasts, and alveolar bone. It also describes the development of the individual tissues - how cementum and periodontal ligament fibers form along the developing root surface, how the gingiva and junctional epithelium develop during tooth eruption, and how alveolar bone develops from the dental follicle to support the tooth socket. The periodontium develops as an integrated unit with interactions between tissues to provide structural support for teeth.
Blood supply,nerve supply and lymphatic drainage of the periodontium finalDr. Neha Pritam
The document discusses the blood supply, nerve supply, and lymphatic drainage of the periodontium. It states that the periodontium receives its blood supply from branches of the internal maxillary artery and its lymphatic drainage involves drainage to local lymph nodes. It also describes the rich nerve supply to the periodontium derived from the trigeminal nerve and its branches. Changes in microcirculation and lymphangiogenesis occur in the periodontium during periodontal disease.
This document summarizes a presentation on the periodontal ligament given by Dr. Abhishek Gakhar. It discusses the structure, development, constituents including cells, fibers and blood/nerve supply of the periodontal ligament. The functions of the periodontal ligament and its clinical correlations are also reviewed. Diagrams illustrate the fiber groups and cells found in the periodontal ligament.
Wound healing [including healing after periodontal therapy]Jignesh Patel
The document discusses wound healing and periodontal wound healing in particular. It describes the processes of regeneration and repair. Regeneration involves renewal of tissues through growth of same tissue type, while repair involves replacement of tissues through scar formation. The molecular biology of wound healing is explained, including roles of fibrin clot, growth factors, matrix degradation and connective tissue formation. Healing by primary and secondary intention is also defined. Healing processes following various periodontal procedures like scaling, root planing, flap surgery and implant placement are outlined. Factors influencing wound healing and potential complications are briefly mentioned.
alveolar bone in health with microscopic features and details about bone formation, resorption also includes bone remodelling and changes after extraction
The document summarizes key information about alveolar bone:
1) Alveolar bone develops from the dental follicle and forms the sockets that hold teeth. It is composed of cortical plates and spongy bone between the plates.
2) The alveolar bone provides protection, attachment, and support for teeth. It also helps absorb forces placed on teeth.
3) Key structures of alveolar bone include the lamina dura lining sockets, interdental septa separating sockets, and Sharpey's fibers that attach the bone to ligaments. Periodontal disease can affect the bone and other supporting tissues.
The document discusses the ultrastructure of gingiva including its microscopic and macroscopic features. It defines gingiva and describes its various parts like the marginal, attached, and interdental gingiva. Microscopically, it consists of stratified squamous epithelium and underlying connective tissue. The epithelium undergoes keratinization and consists of basal, spinous, granular and corneal layers. It protects the underlying tissues and allows selective permeability with the oral environment.
Electrosurgery uses high frequency electrical current to cut, coagulate, and destroy soft tissue. It has several advantages over scalpels for dental procedures, allowing for precise sculpting of tissue without pressure and inherent concurrent hemostasis. Potential disadvantages include unpleasant odor, risk of damaging bone or teeth if contact is made. Proper technique involves using different electrode types and currents depending on the procedure, with rapid movements to prevent tissue burning. Healing occurs via clot formation, inflammation, and growth of new connective and epithelial tissue over several days.
This document discusses the periodontal ligament (PDL), which connects tooth roots to jaw bones. It describes the cells and extracellular matrix of PDL, as well as how they are remodeled through collagen synthesis and degradation. During inflammation or injury, fibroblasts and immune cells can disrupt the collagen through enzymes like matrix metalloproteinases and reactive oxygen species. Cytokines released also influence PDL cell behavior and fibrosis. Bacterial pathogens may further invade PDL and induce host responses through Toll-like receptors. The document outlines how PDL adapts to functional forces on teeth and can develop hyalinization or other changes with excessive forces.
This document provides an overview of bone histology and development. It discusses that bone is a specialized mineralized connective tissue that can be divided into compact and cancellous bone microscopically. Bone develops through either endochondral or intramembranous ossification. The key cells involved are osteoblasts, which form new bone, and osteoclasts, which resorb bone. Bone is remodeled throughout life by the balanced actions of these cells.
Periodontitis is a chronic infectious inflammatory disease caused by microbes; however the presence of microbes is not enough for the cause of its complex nature of disease. Inflammation is the prime cause of periodontal disease. It commences with the aggregation of pathogenic microbes that induce the host to stimulate a cascade of inflammatory response reactions which in-turn leads to the destruction of the host tissues itself. There is a complex interplay of innate and adaptive immune responses which fights against the pathogens by direct interaction or by release of certain molecules including cytokines.
Cytokines are cell signalling molecules that aid cell to cell communication in immune responses and stimulate the movement of cells towards sites of inflammation, infection and trauma. Cytokine biology reveals that there are some subsets of cytokines which are pro-inflammatory cytokines which stimulate the inflammatory responses and cause tissue destruction.
A periodontist is expected to have a sound basis of the cytokine profile to understand the pathogenesis of periodontitis and also to discover the new treatment modality of anti-cytokine therapy.
Alveolar bone forms tooth sockets and provides attachment for the periodontal ligament. It is composed of outer cortical and inner cancellous bone. Osteoblasts form bone matrix containing collagen fibers and hydroxyapatite crystals. Osteoclasts resorb bone. Bone is remodeled through the balanced actions of osteoblasts and osteoclasts, regulated by hormones and growth factors.
This document discusses the anatomy, measurement, and clinical significance of the attached gingiva. It notes that the attached gingiva extends from the base of the gingival sulcus to the mucogingival junction. The normal width is 3-4.5mm in the maxillary anterior region but narrower in other areas. Inadequate width can facilitate subgingival plaque formation. Methods to measure width and increase width through surgery are described. The importance of keratinized, attached tissue for resisting mechanical irritation and stabilizing the gingival margin is emphasized.
This document provides an overview of the anatomy, histology, development and clinical implications of alveolar bone. It describes the components and cellular makeup of bone, including osteoblasts, osteocytes and osteoclasts. It explains that the alveolar process develops with tooth eruption and is resorbed after tooth loss. Factors that regulate bone formation and resorption are discussed. The document also outlines how alveolar bone is affected by tooth loss, orthodontic forces and non-functioning teeth.
This document provides an overview of cementum, the calcified tissue that forms the outer covering of tooth roots. It discusses the development, composition, histology, classification, and functions of cementum. Cementum begins forming at the cementoenamel junction and extends to the root apex. It is made up of inorganic hydroxyapatite and organic collagen fibers. Cementum provides a medium for periodontal ligament attachment and protects underlying dentin, helping to maintain tooth integrity under forces. It is capable of continuous deposition to repair damage or resorption on root surfaces.
The document discusses aging changes that occur in the periodontium. Key points:
- With aging, the gingival epithelium thickens due to acanthosis. Connective tissue ridges become more prevalent in young individuals while papillae predominate in old individuals.
- The periodontal ligament has greater elastic fibers, decreased vascularity and cellular elements, and altered collagen with aging. Alveolar bone shows increased osteoporosis and irregular surfaces facing the ligament.
- Subgingival plaque in older adults contains more enteric rods and pseudomonads, and increased pathogens like P. gingivalis. Periodontitis is associated with increased risk of conditions like diabetes, coronary
Coronal advanced flap in combination with a connective tissue graft. Is the t...MD Abdul Haleem
Coronal advanced flap in combination with a connective tissue graft. Is the thickness of the flap a predictor for root coverage? - A prospective clinical study.
Department of Periodontology and Oral Implantology.
"A Journal Club Presentation"
The periodontium develops from the dental follicle, which gives rise to the cementum, periodontal ligament, and alveolar bone. Cementum is deposited on the root surface by cementoblasts derived from the follicle. The periodontal ligament develops as collagen fibers remodel between the cementum and bone. The dental follicle also forms the bony crypt and gives rise to osteoblasts that deposit alveolar bone. Remnants of the epithelial root sheath become the epithelial cell rests of Malassez. The gingiva develops as the reduced enamel epithelium transforms into the junctional epithelium during tooth eruption.
This document discusses the effects of various hormones from the endocrine system on the periodontium. It begins with an introduction to periodontitis and the role of the endocrine system. It then discusses the central endocrine glands of the hypothalamus and pituitary, as well as peripheral glands including the thyroid, parathyroid, pancreas, and adrenal glands. For each gland, it summarizes the hormones secreted and their effects on the periodontium, such as accelerated bone loss from hyperthyroidism, increased tooth loss with hyperparathyroidism, increased risk of periodontitis in diabetes, and reduced immune response from glucocorticoids. Sex steroid hormones from the ovaries and test
Classification Systems of Periodontal Diseases Manu Bhaskaran
This document discusses the history and development of classification systems for periodontal diseases. It begins with early classification attempts in the late 19th century based primarily on clinical features. In the 1920-1970 period, classifications were dominated by the "classical pathology" paradigm focusing on non-inflammatory degenerative forms of periodontitis. Starting in the 1970s, the "infection/host response" paradigm emerged as the dominant view, recognizing periodontitis as inflammatory diseases caused by bacterial infection. The document reviews several influential classification systems developed under this new paradigm from the 1970s to present day.
The periodontium develops from neural crest cells that migrate into the developing dental arches. The dental lamina forms and invaginates into the underlying mesenchyme, forming the tooth bud. The bud develops through the cap and bell stages as the enamel organ and dental papilla form. The dental follicle gives rise to the periodontal ligament, cementum and alveolar bone. Cementoblasts deposit cementum on the root surface. Periodontal ligament fibers develop from the dental follicle and insert into the cementum and bone. The gingiva develops as the tooth erupts, with the reduced enamel epithelium transforming into junctional epithelium and sulcular epithelium.
This document discusses genetics in relation to periodontitis. It provides background on genetic study designs like segregation analysis, twin studies, and linkage/association studies that are used to identify genes associated with periodontal diseases. Specific genes linked to aggressive periodontitis are mentioned, including mutations in the alkaline phosphatase, cathepsin C, and CD18/CD11 genes. Studies finding autosomal dominant and recessive inheritance of aggressive periodontitis in different populations are summarized. The role of HLA antigens and IL-1 gene polymorphisms in periodontitis susceptibility is also briefly covered.
Microscopic features of Gingiva by DR SUHANI GOELdr suhani goel
The document summarizes the microscopic features of gingiva. It describes the different layers of the oral epithelium including the stratum basale, stratum spinosum, stratum granulosum, and stratum corneum. It also discusses the sulcular epithelium and junctional epithelium. The connective tissue of the gingiva contains collagen, reticulin and elastic fibers as well as fibroblasts, macrophages and mast cells. Blood supply to the gingiva is provided by suprapapillary arterioles and arteries from the crest of the interdental septa. Lymphatic drainage occurs through vessels that accompany the blood vessels.
This document summarizes the development of the periodontium, which consists of the gingiva, periodontal ligament, cementum and alveolar bone. It describes how the dental lamina forms and then divides into the inner and outer processes. Tooth development occurs through the bud, cap and bell stages as the enamel organ forms. Hertwig's epithelial root sheath induces root formation and cementum development. The periodontal ligament then develops from the dental follicle, with principle fibers forming between the cementum and alveolar bone.
development of root, Root formation and periodontal ligamentAkram bhuiyan
The document describes the development of the dental pulp and root formation. It discusses how the dental pulp develops from mesenchymal cells that differentiate into odontoblasts. During the bell stage, the dental papilla forms and the cells within differentiate into odontoblasts and fibroblasts. The dental follicle surrounds the developing tooth structures. Root formation is guided by the Hertwig's epithelial root sheath, which determines the root morphology. Blood vessels and nerves enter the developing pulp. Cementum formation begins with primary acellular cementum laid down by cementoblasts. Secondary cellular cementum is later formed and incorporates cells.
The document summarizes key information about alveolar bone:
1) Alveolar bone develops from the dental follicle and forms the sockets that hold teeth. It is composed of cortical plates and spongy bone between the plates.
2) The alveolar bone provides protection, attachment, and support for teeth. It also helps absorb forces placed on teeth.
3) Key structures of alveolar bone include the lamina dura lining sockets, interdental septa separating sockets, and Sharpey's fibers that attach the bone to ligaments. Periodontal disease can affect the bone and other supporting tissues.
The document discusses the ultrastructure of gingiva including its microscopic and macroscopic features. It defines gingiva and describes its various parts like the marginal, attached, and interdental gingiva. Microscopically, it consists of stratified squamous epithelium and underlying connective tissue. The epithelium undergoes keratinization and consists of basal, spinous, granular and corneal layers. It protects the underlying tissues and allows selective permeability with the oral environment.
Electrosurgery uses high frequency electrical current to cut, coagulate, and destroy soft tissue. It has several advantages over scalpels for dental procedures, allowing for precise sculpting of tissue without pressure and inherent concurrent hemostasis. Potential disadvantages include unpleasant odor, risk of damaging bone or teeth if contact is made. Proper technique involves using different electrode types and currents depending on the procedure, with rapid movements to prevent tissue burning. Healing occurs via clot formation, inflammation, and growth of new connective and epithelial tissue over several days.
This document discusses the periodontal ligament (PDL), which connects tooth roots to jaw bones. It describes the cells and extracellular matrix of PDL, as well as how they are remodeled through collagen synthesis and degradation. During inflammation or injury, fibroblasts and immune cells can disrupt the collagen through enzymes like matrix metalloproteinases and reactive oxygen species. Cytokines released also influence PDL cell behavior and fibrosis. Bacterial pathogens may further invade PDL and induce host responses through Toll-like receptors. The document outlines how PDL adapts to functional forces on teeth and can develop hyalinization or other changes with excessive forces.
This document provides an overview of bone histology and development. It discusses that bone is a specialized mineralized connective tissue that can be divided into compact and cancellous bone microscopically. Bone develops through either endochondral or intramembranous ossification. The key cells involved are osteoblasts, which form new bone, and osteoclasts, which resorb bone. Bone is remodeled throughout life by the balanced actions of these cells.
Periodontitis is a chronic infectious inflammatory disease caused by microbes; however the presence of microbes is not enough for the cause of its complex nature of disease. Inflammation is the prime cause of periodontal disease. It commences with the aggregation of pathogenic microbes that induce the host to stimulate a cascade of inflammatory response reactions which in-turn leads to the destruction of the host tissues itself. There is a complex interplay of innate and adaptive immune responses which fights against the pathogens by direct interaction or by release of certain molecules including cytokines.
Cytokines are cell signalling molecules that aid cell to cell communication in immune responses and stimulate the movement of cells towards sites of inflammation, infection and trauma. Cytokine biology reveals that there are some subsets of cytokines which are pro-inflammatory cytokines which stimulate the inflammatory responses and cause tissue destruction.
A periodontist is expected to have a sound basis of the cytokine profile to understand the pathogenesis of periodontitis and also to discover the new treatment modality of anti-cytokine therapy.
Alveolar bone forms tooth sockets and provides attachment for the periodontal ligament. It is composed of outer cortical and inner cancellous bone. Osteoblasts form bone matrix containing collagen fibers and hydroxyapatite crystals. Osteoclasts resorb bone. Bone is remodeled through the balanced actions of osteoblasts and osteoclasts, regulated by hormones and growth factors.
This document discusses the anatomy, measurement, and clinical significance of the attached gingiva. It notes that the attached gingiva extends from the base of the gingival sulcus to the mucogingival junction. The normal width is 3-4.5mm in the maxillary anterior region but narrower in other areas. Inadequate width can facilitate subgingival plaque formation. Methods to measure width and increase width through surgery are described. The importance of keratinized, attached tissue for resisting mechanical irritation and stabilizing the gingival margin is emphasized.
This document provides an overview of the anatomy, histology, development and clinical implications of alveolar bone. It describes the components and cellular makeup of bone, including osteoblasts, osteocytes and osteoclasts. It explains that the alveolar process develops with tooth eruption and is resorbed after tooth loss. Factors that regulate bone formation and resorption are discussed. The document also outlines how alveolar bone is affected by tooth loss, orthodontic forces and non-functioning teeth.
This document provides an overview of cementum, the calcified tissue that forms the outer covering of tooth roots. It discusses the development, composition, histology, classification, and functions of cementum. Cementum begins forming at the cementoenamel junction and extends to the root apex. It is made up of inorganic hydroxyapatite and organic collagen fibers. Cementum provides a medium for periodontal ligament attachment and protects underlying dentin, helping to maintain tooth integrity under forces. It is capable of continuous deposition to repair damage or resorption on root surfaces.
The document discusses aging changes that occur in the periodontium. Key points:
- With aging, the gingival epithelium thickens due to acanthosis. Connective tissue ridges become more prevalent in young individuals while papillae predominate in old individuals.
- The periodontal ligament has greater elastic fibers, decreased vascularity and cellular elements, and altered collagen with aging. Alveolar bone shows increased osteoporosis and irregular surfaces facing the ligament.
- Subgingival plaque in older adults contains more enteric rods and pseudomonads, and increased pathogens like P. gingivalis. Periodontitis is associated with increased risk of conditions like diabetes, coronary
Coronal advanced flap in combination with a connective tissue graft. Is the t...MD Abdul Haleem
Coronal advanced flap in combination with a connective tissue graft. Is the thickness of the flap a predictor for root coverage? - A prospective clinical study.
Department of Periodontology and Oral Implantology.
"A Journal Club Presentation"
The periodontium develops from the dental follicle, which gives rise to the cementum, periodontal ligament, and alveolar bone. Cementum is deposited on the root surface by cementoblasts derived from the follicle. The periodontal ligament develops as collagen fibers remodel between the cementum and bone. The dental follicle also forms the bony crypt and gives rise to osteoblasts that deposit alveolar bone. Remnants of the epithelial root sheath become the epithelial cell rests of Malassez. The gingiva develops as the reduced enamel epithelium transforms into the junctional epithelium during tooth eruption.
This document discusses the effects of various hormones from the endocrine system on the periodontium. It begins with an introduction to periodontitis and the role of the endocrine system. It then discusses the central endocrine glands of the hypothalamus and pituitary, as well as peripheral glands including the thyroid, parathyroid, pancreas, and adrenal glands. For each gland, it summarizes the hormones secreted and their effects on the periodontium, such as accelerated bone loss from hyperthyroidism, increased tooth loss with hyperparathyroidism, increased risk of periodontitis in diabetes, and reduced immune response from glucocorticoids. Sex steroid hormones from the ovaries and test
Classification Systems of Periodontal Diseases Manu Bhaskaran
This document discusses the history and development of classification systems for periodontal diseases. It begins with early classification attempts in the late 19th century based primarily on clinical features. In the 1920-1970 period, classifications were dominated by the "classical pathology" paradigm focusing on non-inflammatory degenerative forms of periodontitis. Starting in the 1970s, the "infection/host response" paradigm emerged as the dominant view, recognizing periodontitis as inflammatory diseases caused by bacterial infection. The document reviews several influential classification systems developed under this new paradigm from the 1970s to present day.
The periodontium develops from neural crest cells that migrate into the developing dental arches. The dental lamina forms and invaginates into the underlying mesenchyme, forming the tooth bud. The bud develops through the cap and bell stages as the enamel organ and dental papilla form. The dental follicle gives rise to the periodontal ligament, cementum and alveolar bone. Cementoblasts deposit cementum on the root surface. Periodontal ligament fibers develop from the dental follicle and insert into the cementum and bone. The gingiva develops as the tooth erupts, with the reduced enamel epithelium transforming into junctional epithelium and sulcular epithelium.
This document discusses genetics in relation to periodontitis. It provides background on genetic study designs like segregation analysis, twin studies, and linkage/association studies that are used to identify genes associated with periodontal diseases. Specific genes linked to aggressive periodontitis are mentioned, including mutations in the alkaline phosphatase, cathepsin C, and CD18/CD11 genes. Studies finding autosomal dominant and recessive inheritance of aggressive periodontitis in different populations are summarized. The role of HLA antigens and IL-1 gene polymorphisms in periodontitis susceptibility is also briefly covered.
Microscopic features of Gingiva by DR SUHANI GOELdr suhani goel
The document summarizes the microscopic features of gingiva. It describes the different layers of the oral epithelium including the stratum basale, stratum spinosum, stratum granulosum, and stratum corneum. It also discusses the sulcular epithelium and junctional epithelium. The connective tissue of the gingiva contains collagen, reticulin and elastic fibers as well as fibroblasts, macrophages and mast cells. Blood supply to the gingiva is provided by suprapapillary arterioles and arteries from the crest of the interdental septa. Lymphatic drainage occurs through vessels that accompany the blood vessels.
This document summarizes the development of the periodontium, which consists of the gingiva, periodontal ligament, cementum and alveolar bone. It describes how the dental lamina forms and then divides into the inner and outer processes. Tooth development occurs through the bud, cap and bell stages as the enamel organ forms. Hertwig's epithelial root sheath induces root formation and cementum development. The periodontal ligament then develops from the dental follicle, with principle fibers forming between the cementum and alveolar bone.
development of root, Root formation and periodontal ligamentAkram bhuiyan
The document describes the development of the dental pulp and root formation. It discusses how the dental pulp develops from mesenchymal cells that differentiate into odontoblasts. During the bell stage, the dental papilla forms and the cells within differentiate into odontoblasts and fibroblasts. The dental follicle surrounds the developing tooth structures. Root formation is guided by the Hertwig's epithelial root sheath, which determines the root morphology. Blood vessels and nerves enter the developing pulp. Cementum formation begins with primary acellular cementum laid down by cementoblasts. Secondary cellular cementum is later formed and incorporates cells.
The document describes the development of the dental pulp and root formation. It discusses:
- How the dental pulp develops from mesenchymal cells that differentiate into odontoblasts and fibroblasts.
- How the dental papilla and follicle form during the bud and cap stages and their roles in tooth development.
- How odontoblasts and cementoblasts differentiate during the bell stage to lay down dentin and cementum.
- The development of blood vessels and nerves that enter the dental pulp.
- How root formation is directed by the Hertwig's epithelial root sheath and how this determines root morphology.
- The formation of acellular cementum on root surfaces by
Development of periodontium. periodonticsGururam MDS
This document provides an overview of tooth and periodontal tissue development. It discusses how neural crest cells give rise to dental and periodontal structures. Tooth development progresses through bud, cap, and bell stages as the enamel organ and dental papilla interact. Cementum, periodontal ligament, and alveolar bone develop during root formation guided by Hertwig's epithelial root sheath. The gingiva develops from both epithelial and connective tissue precursors. Epithelial-mesenchymal interactions are important for maintaining tissue phenotypes and regulating epithelial growth.
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1. The primitive oral cavity is lined by a 2-3 cell thick layered epithelium covering embryonic connective tissue formed from neural crest cells.
2. Tooth development involves three overlapping phases: initiation, morphogenesis, and histogenesis, during which dental tissues differentiate.
3. The first sign of tooth development is the formation of a continuous epithelial band around the primitive oral cavity, which divides into vestibular and dental lamina. The dental lamina then invaginates and forms 20 buds for the primary teeth.
This document provides an overview of the development of dental and periodontal tissues. It discusses how neural crest cells give rise to dental tissues like cementum, periodontal ligament, and alveolar bone. Tooth development progresses from the bud stage to the bell stage to root formation directed by Hertwig's epithelial root sheath. Cementum develops through cellular cementoblasts on the root surface. The periodontal ligament develops from the dental follicle with fibers inserting into cementum and bone. Alveolar bone forms during root development through osteoblasts. The gingiva develops from the oral epithelium and underlying connective tissue, with the gingival sulcus forming as teeth erupt. Epithelial and
The initiation of tooth development begins at 37 days of development
with formation of a continuous horseshoe-band of thickened epithelium
in the location of upper and lower jaws – Primary Epithelial Band
Dental lamina appears as a thickening
of the oral epithelium adjacent to
condensation of ectomesenchyme
20 areas of enlargement or knobs
appear, which will form tooth buds
for the 20 primary teeth
Not all will appear at the same time.
The first to develop are those of the
anterior mandible region
At this early stage the tooth buds
have already determined their crown morphology
Successional lamina: lamina from
which permanent teeth develop
The dental lamina begins to function
at 6th prenatal week and continues to
15th year of birth (3rd molar)
Tooth development is a continuous process, however can be
divided into 3 stages:
1. Bud Stage
2. Cap Stage
3. Bell Stage
4. Hertwigs epithelial root sheath and root formation
The bud stage is represented by the first epithelial incursion into the ectomesenchyme of the jaw.
The epithelial cells show little if any change in shape or function.
The supporting ectomesenchymal cells are packed closely beneath and around the epithelial bud. As the epithelial bud continues to proliferate into the ectomesenchyme, cellular density increases immediately adjacent to the epithelial outgrowth.
This process is classically referred to as a condensation of the ectomesenchyme.
The epithelium of the dental lamina separated from the underlying ectomesenchyme by basement membrane.
Bud stage is characterized by rounded, localized growth of
epithelium surrounded by proliferating mesenchymal cells,which are packed closely beneath and around the epithelial buds
The transition from bud to cap marks the onset of morphologic differences between tooth germs that give rise to different types of teeth.
Differential cellular division in the epithelial bud initiates a change in shape so that now the epithelial outgrowth assumes a more complex outline with a flattened internal portion along which the mesenchymal condensation densifies.
As the tooth bud grows larger, it drags along with it part of the dental lamina; thus from that point on, the developing tooth is tethered to the dental lamina by an extension called the lateral lamina.
At this early stage of tooth development, identifying the formative elements of the tooth and its supporting tissues is already possible.
The epithelial outgrowth, which superficially resembles a cap sitting on a ball of condensed ectomesenchyme , is still referred to widely as the dental organ but actually should be called the enamel organ, because it eventually will form the enamel of the tooth. Henceforth, the term enamel organ is used.
Condensation of the ectomesenchyme immediately subjacent to the tooth bud caused by lack of extracellular matrix secretion by the cells thus preventing separation.
This document provides an overview of dental cementum, including its development, structure, composition and functions. It discusses the different types of cementum (acellular afibrillar, acellular extrinsic fiber, cellular intrinsic fiber, cellular mixed stratified), how they form and where they are located on tooth roots. It also describes the organic and mineral components of cementum and how it mineralizes. In summary, cementum is a mineralized tissue covering tooth roots, it develops over many years both before and after tooth eruption, and has different types and structures tailored to its roles in anchoring teeth and repairing root surfaces.
The early development of tooth from six week of prenatal life. Description of different stages- bud,cap and bell stage and amelogenesis, dentinogenesis. Description of root development.
DENTAL_PULP_AND_PERIRADICULAR_TISSUE (8).pptx, INFLAMMATION, N DISEASESaishwaryakhare5
The document summarizes the development of teeth from the initial formation of the dental lamina through the development of the crown and roots. It describes how the dental pulp develops from the dental papilla and how the interaction between the inner enamel epithelium and ectomesenchyme leads to the formation of dentin, enamel, and cementum. Key stages of tooth development discussed include the bud, cap, and bell stages of the crown as well as the role of Hertwig's epithelial root sheath in root formation.
Chronology of dental development and development of occlusionshilpathaklotra
The document summarizes key stages of dental development and changes in dental arches:
- Tooth development begins with thickening of oral epithelium, forming the primary epithelial band that invades underlying mesenchyme. This forms the dental lamina which serves as the primordium for deciduous teeth.
- Teeth develop through bud, cap, bell, and advanced bell stages. During these stages, the enamel organ and dental papilla form and cells differentiate into ameloblasts and odontoblasts. Enamel knots organize cuspal morphogenesis.
- Root formation begins after crown formation is complete, guided by Hertwig's epithelial root sheath which induces dentin formation and shapes
Hertwig's epithelial root sheath is broken up and separated from the root, allowing differentiation of cementoblasts and formation of cementum. This marks the transition from root formation to development of the periodontium, including the periodontal ligament, cementum, and alveolar bone. Mesenchymal cells in the dental follicle and perifollicular region develop into fibroblasts that synthesize collagen fibers and other proteins to form the principal fiber groups of the periodontal ligament. Homeostasis of the periodontium is maintained by regulators that prevent mineralization and allow proliferation and remodeling of tissues in response to forces.
The document discusses the complex process of tooth development from initiation to eruption. It begins with the formation of the primary epithelial bands and dental lamina between 6-7 weeks in utero, which give rise to the tooth buds. The buds progress through stages of proliferation, histodifferentiation, and morphodifferentiation to form the crown and root structures. Hertwig's epithelial root sheath is responsible for root formation and shape before teeth erupt into the oral cavity.
Dentin is the mineralized hard tissue that forms the bulk of the tooth beneath enamel and cementum. It has two main properties that distinguish it from enamel: it is sensitive and forms throughout life at the expense of the dental pulp. Dentinogenesis, or dentin formation, begins when the tooth germ reaches the bell stage. Odontoblasts differentiate from ectomesenchymal cells of the dental papilla and secrete dentin matrix, which then undergoes mineralization to form the bulk of dentin, including mantle dentin and circumpulpal dentin. This process of matrix formation and mineralization by odontoblasts is ongoing throughout life.
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Development Of Dentition & Occlusionjinishnath
The document discusses the development of dentition and occlusion from pre-natal development through post-natal development in humans. It covers:
- Pre-natal development of teeth including formation of the dental lamina and enamel organs.
- Stages of tooth development including bud, cap, and bell stages.
- Formation of the root and root sheath.
- Theories of tooth eruption.
- Post-natal development from birth through completion of primary dentition and the transitional periods involving eruption of permanent teeth.
The document discusses tooth development from the intrauterine life stage through the bell stage. It describes the key stages and structures involved, including the dental lamina, bud stage, cap stage, and early bell stage. During these stages, the enamel organ, dental papilla, and dental sac develop and differentiate. Structures like the enamel knot, enamel cord, and cervical loop form transiently to guide tooth morphogenesis. By the early bell stage, the inner dental epithelium induces the underlying mesenchyme to form odontoblasts, marking the beginning of dentin formation.
For first year dental student, i got this from the internet.. Hope this can help u guys understand more about the tooth development.. Btw, good luck for minitest OB tomorrow.. No sacrifice, no victory!
The document discusses basic concepts of occlusion including terminology, the masticatory system, types of occlusion, forces of occlusion, bruxism, pathological tooth migration, and trauma from occlusion. It defines key terms, classifies different types of occlusion, and explores the etiology and clinical signs of conditions like bruxism and trauma from occlusion.
advanced diagnostic aids in periodonticsMehul Shinde
Advanced diagnostic aids provide more precise tools and technologies for diagnosis. New probes allow for controlled pressure and automated measurement. Digital radiography provides advantages like reduced radiation dose and immediate imaging. Techniques like digital subtraction radiography and cone-beam computed tomography improve detection of bone changes over time. Overall, advances in clinical, radiographic, microbiological and host-response assessments enhance diagnosis of disease presence, type and progression.
This document discusses host modulation therapies for the treatment of periodontal disease. It first introduces concepts of host modulation and describes how therapies aim to downregulate destructive aspects of the host inflammatory response. A major focus is on matrix metalloproteinases (MMPs), which degrade connective tissue during periodontal disease. The document outlines various stages of MMP inhibition that could be targeted therapeutically, including inhibiting MMP induction, activation of latent MMPs, and upregulating natural MMP inhibitors. It provides extensive details on the mechanisms and clinical studies of sub-antimicrobial doses of doxycycline, one of the few approved host modulation drugs for treating periodontitis.
This document discusses the relationship between smoking and periodontal disease. It begins by introducing tobacco smoking as a detrimental habit and risk factor for systemic diseases. It then explores the constituents of tobacco smoke and the mechanisms by which smoking can increase toxicity and periodontal disease risk. Subsequent sections examine the effects of smoking on plaque, periodontal tissues, immunology/host response, and how smoking may impact periodontal therapy and systemic health. The document concludes by emphasizing the long-term chronic negative effects of smoking on the periodontium.
This document provides an overview of viruses and their role in periodontal disease. It begins with definitions of viruses and their classification. It then discusses the structure and life cycle of viruses, how the host responds to viral infections, and specific viruses implicated in periodontal disease like herpes viruses and HIV. The document proposes a model where herpes virus activation in the gingiva can enhance the pathogenic potential of bacteria and contribute to periodontal tissue destruction over time, especially in immunosuppressed individuals. It reviews evidence that herpes viral DNA is detected more frequently in gingival tissue and crevicular fluid from periodontally diseased sites compared to healthy sites.
This document discusses different types of gingival enlargement, including classifications based on etiology and location. Inflammatory enlargements can be acute or chronic, with chronic enlargement resulting from plaque accumulation. Systemic diseases like leukemia and granulomatous diseases can also cause enlargement. Neoplastic enlargements include benign tumors like fibromas and papillomas, as well as malignant tumors like squamous cell carcinoma. Drug-induced enlargement is a common side effect of medications like anticonvulsants, immunosuppressants, and calcium channel blockers. The document also covers indices used to grade the severity of enlargement.
This document discusses the classification, pathogenesis, histopathology, and progression of periodontal pockets. Periodontal pockets are classified as suprabony or intrabony based on their location relative to the alveolar bone. Theories on the pathogenesis suggest pockets form due to bacterial invasion, inflammation, or proliferation of the junctional epithelium leading to destruction of connective tissue and loss of attachment. Histopathology shows the soft tissue wall undergoes degenerative changes while the root surface develops structural and chemical alterations. Pockets progress in an episodic manner with periods of exacerbation and quiescence. Understanding the etiology and progression of pockets is important for providing successful treatment and monitoring response to therapy.
Periodontal diseases are highly prevalent globally and their distribution is influenced by factors like age, gender, geography, and oral hygiene habits. Gingivitis is the most common form of periodontal disease and prevalence surveys show that it affects a large portion of all populations. The prevalence of periodontitis increases with age, from 35% in 35-40 year olds to 85% in 80-90 year olds. Risk factors for periodontal diseases include tobacco use, diabetes, poor oral hygiene leading to dental plaque and calculus buildup, and specific pathogenic bacteria. Epidemiological studies are important to understand the distribution and determinants of periodontal diseases in populations in order to guide prevention and control efforts.
Collagenases, elastase, cathepsins, dipeptidylpeptidases, and tryptase are proteolytic enzymes that can be biomarkers for periodontal diseases. Studies have found increased levels of these enzymes in gingival tissue, saliva, and gingival crevicular fluid of patients with periodontal diseases compared to healthy patients. Other potential biomarkers discussed include hydrolytic enzymes like beta-glucuronidase and cytosolic enzymes like aspartate aminotransferase. Markers of connective tissue degradation like hydroxyproline and glycosaminoglycans have also been studied but techniques for isolation and detection are too complex for clinical use. Overall, certain proteolytic enzymes show potential as
This document provides an overview of aggressive periodontitis, including:
- A brief history of terminology used and key publications.
- Classification into localized and generalized forms based on extent of disease.
- Epidemiology showing prevalence under 1% and higher rates in some populations.
- Clinical features of each form including patterns of bone and attachment loss.
- Role of microbes like Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis in etiology.
- Importance of genetic and immunological factors in disease pathogenesis and progression.
- Diagnosis involving clinical exams, microbiological testing, and evaluation of host defenses.
- Treatment aimed
This document provides an overview of chronic periodontitis. It discusses the introduction, history, prevalence, etiology, pathogenesis, clinical features, models of disease progression, microbiological and immunological considerations, and risk factors of chronic periodontitis. Chronic periodontitis is a complex polymicrobial infection that results from an imbalance between pathogenic bacteria in plaque and the host immune response. It begins as plaque-induced gingivitis and progresses to the destruction of connective tissue and alveolar bone through periods of activity and remission, leading to pocket formation and potential tooth loss over time if left untreated. Systemic and environmental risk factors like smoking can increase the risk and rate of disease progression.
This document provides an overview of desquamative gingivitis, a group of immune-mediated disorders that cause inflammation and sloughing of the gingival epithelium. It discusses the classification, associated disorders like lichen planus and pemphigoid, clinical presentation, histopathology, diagnosis and treatment. Desquamative gingivitis can be caused by conditions like mucous membrane pemphigoid, lichen planus, and pemphigus vulgaris. It is characterized by red, swollen gingiva with areas of denudation and vesicles. Diagnosis involves clinical evaluation, histopathology, and immunopathology testing. Management depends on the underlying disorder but may include top
This document discusses HIV and its oral manifestations, with a focus on periodontal diseases. It covers the epidemiology and pathogenesis of HIV, describing how it depletes CD4 cells and impacts the immune system. Various oral conditions associated with HIV are described, including oral candidiasis, oral hairy leukoplakia, Kaposi's sarcoma, and necrotizing periodontal diseases. The pathogenesis of HIV-associated periodontal diseases is explained. Treatment protocols for different oral conditions in HIV patients emphasize the importance of infection control and the patient's overall health status.
This document discusses the potential linkages between periodontal disease and systemic diseases like coronary heart disease and stroke. It suggests that periodontal disease may influence these conditions through three main mechanisms: shared risk factors, the periodontium acting as a reservoir for bacteria and inflammatory mediators, and transient bacteremias from periodontal infections potentially causing endothelial dysfunction. The document reviews evidence on specific inflammatory markers and pathogens that may provide biological pathways for this periodontal-systemic connection. It proposes models to explain potential direct and indirect impacts of periodontal infection on atheroma formation and thrombus development that can lead to heart disease and stroke.
Influence of laser lok surface on immediate functional loading - implant jcMehul Shinde
This study compared the clinical outcomes of immediate loading of dental implants with a Laser-Lok surface vs a non-Laser-Lok surface for single tooth replacements over 3 years. It found that the Laser-Lok implants showed less marginal bone loss, better papilla fill, and higher pink esthetic scores compared to non-Laser-Lok implants. The Laser-Lok surface's microgrooves were found to better orient fibroblast growth and provide more soft tissue support, resulting in reduced epithelial downgrowth and greater clinical success for immediate loading in the esthetic zone.
This document provides an overview of blood, including its composition, functions, and various components and properties. Key points include:
- Blood is a specialized connective tissue composed of plasma, red blood cells, white blood cells, and platelets suspended in plasma.
- Hemoglobin is the protein in red blood cells that carries oxygen throughout the body. Different types of hemoglobin can cause conditions like sickle cell anemia.
- Blood grouping refers to the presence or absence of antigens on red blood cells, which determines blood type and compatibility for transfusions. Incompatible blood can cause transfusion reactions.
- Various blood-related conditions are discussed like anemias, polycythemia, and hemoglobinopathies
This document provides an overview of the mandible, including its development, anatomy, age-related changes, and clinical applications. It discusses how the mandible develops from the first pharyngeal arch and ossifies through both intramembranous and endochondral bone formation. The anatomy of the mandible is described in detail, including its various parts and structures. Age-related changes to the mandible from birth through adulthood and old age are also reviewed. Finally, the document discusses some applied clinical aspects of the mandible relating to dislocations, fractures, and considerations for surgery.
systemic anti-microbials in periodontal therapyMehul Shinde
This document discusses the use of systemic antimicrobials in periodontal therapy. It provides an overview of the rationale for using antibiotics to treat periodontal diseases, commonly prescribed antibiotics like amoxicillin, metronidazole, tetracyclines, and their mechanisms of action, side effects, and clinical usage. Guidelines for antibiotic use recommend they be used as an adjunct to scaling and root planing based on microbial analysis and not as monotherapy. The ideal antibiotic would be pathogen-specific, non-toxic, substantive, and inexpensive.
The temporomandibular joint (TMJ) is a complex joint that connects the mandible to the temporal bone. It has three parts: the condyle of the mandible, the articular disc, and the glenoid fossa-articular eminence of the temporal bone. The TMJ is a synovial joint that allows hinge-like and gliding motions to facilitate functions like chewing and speaking. It continues developing postnatally, with the condyle and articular eminence growing in size and complexity through childhood and adolescence. The articular disc divides the joint cavity and aids in load distribution and lubrication during jaw movements.
This document provides information on various vitamins. It begins with an introduction that defines vitamins and their classification. It then discusses individual vitamins - Vitamins A, D, E, K, B, and C. For each vitamin, it describes chemistry, biochemical functions, deficiency symptoms, recommended dietary allowances, and implications for dental and periodontal health. The document concludes with references. It serves as a comprehensive yet concise review of the essential roles and impacts of different vitamins.
Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
Leveraging Generative AI to Drive Nonprofit InnovationTechSoup
In this webinar, participants learned how to utilize Generative AI to streamline operations and elevate member engagement. Amazon Web Service experts provided a customer specific use cases and dived into low/no-code tools that are quick and easy to deploy through Amazon Web Service (AWS.)
Strategies for Effective Upskilling is a presentation by Chinwendu Peace in a Your Skill Boost Masterclass organisation by the Excellence Foundation for South Sudan on 08th and 09th June 2024 from 1 PM to 3 PM on each day.
Walmart Business+ and Spark Good for Nonprofits.pdfTechSoup
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Walmart Business + (https://business.walmart.com/plus) is a new shopping experience for nonprofits, schools, and local business customers that connects an exclusive online shopping experience to stores. Benefits include free delivery and shipping, a 'Spend Analytics” feature, special discounts, deals and tax-exempt shopping.
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Spark Good (walmart.com/sparkgood) is a charitable platform that enables nonprofits to receive donations directly from customers and associates.
Answers about how you can do more with Walmart!"
বাংলাদেশের অর্থনৈতিক সমীক্ষা ২০২৪ [Bangladesh Economic Review 2024 Bangla.pdf] কম্পিউটার , ট্যাব ও স্মার্ট ফোন ভার্সন সহ সম্পূর্ণ বাংলা ই-বুক বা pdf বই " সুচিপত্র ...বুকমার্ক মেনু 🔖 ও হাইপার লিংক মেনু 📝👆 যুক্ত ..
আমাদের সবার জন্য খুব খুব গুরুত্বপূর্ণ একটি বই ..বিসিএস, ব্যাংক, ইউনিভার্সিটি ভর্তি ও যে কোন প্রতিযোগিতা মূলক পরীক্ষার জন্য এর খুব ইম্পরট্যান্ট একটি বিষয় ...তাছাড়া বাংলাদেশের সাম্প্রতিক যে কোন ডাটা বা তথ্য এই বইতে পাবেন ...
তাই একজন নাগরিক হিসাবে এই তথ্য গুলো আপনার জানা প্রয়োজন ...।
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1. DEVELOPMENT OF PERIODONTIUM
“You never know where you are going unless you know where you came from”
DR. T.MADHAVI
PERIO PG
The periodontium is defined as those tissues supporting & investing the tooth,
comprising of
1. Cementum
2. Periodontal ligament
3. Bone lining the alveolus (socket)
4. That part of the gingiva facing the tooth
Following the development of the neural tube, the neural crest cells (NCC) migrate
from the dorsal midline region of the neural tube to invade the developing branchial
arches. Dye injected tracings have shown that neural crest cells from the posterior
midbrain, and to a lesser extent from the anterior hindbrain, form dental
ectomesenchyme. Subsets of cranial neural crest cells give rise to chondrocytes,
osteoblasts, periodontal ligament fibroblasts, cementoblasts and odontoblasts.
The failure of the normal migration of neural crest ectomesenchymal cells to
appropriate sites during craniofacial development leads to serious developmental
defects.
Dental lamina
Two or three weeks after the rupture of the buccopharyngeal membrane, when the
embryo is 6 weeks old, certain areas of basal cells of the oral ectoderm proliferate
2. more rapidly. This leads to formation of the dental lamina. It is a band of epithelium
that has invaded the underlying ectomesenchyme along each of the horseshoe- shaped
future dental arches. The dental laminae serve as the primordium for the ectodermal
portion of the deciduous teeth.
Tooth Development
The developmental history of a tooth is divided into several morphogenetic “stages”.
They are named after the shape of the epithelial part of the tooth germ and are called
Bud stage
Cap stage
Bell stage
Bud stage: Portions of epithelium in dental lamina, first begin to aggregate and
invaginate into underlying connective tissue
Cap stage: the enamel organ is in its earliest stage of development. The dental papilla
and dental follicle are formed by concentration of neural crest ectomesenchyme cells.
The interaction b/w cell surface syndecan and tenascin (extra cellular matrix adhesion
molecule) reduces migration and promotes aggregation of the ectomesenchymal cells
to form papilla & follicle.
3. Immediately underneath the epithelial cap, mesenchymal cells begin to proliferate and
form dental papilla. These cells further proliferate and encapsulate the enamel organ
to form dental sac.
(The syndecans: In the early 1990s a group of scientists discovered that a number of
components of the extra-cellular microenvironment had a high affinity for binding
with heparin. These extra-cellular components included growth factor peptides,
proteases, antiproteases and ECM molecules which, by binding to a cell, could
produce changes in cell shape, motility, adhesion, proliferation and differentiation.
They discovered that there is a family of integral membrane proteoglycans made up of
heparan and chondroitin sulphate, both structural analogues of heparin, which can
also bind to a wide variety of structural proteins and growth factors in the internal
and external cellular environment. They named these molecules the syndecans, from
the Greek ‘syndein’ which means ‘to bind together’. It has since been shown that by
binding to extra-cellular ligands, syndecans can mediate the activity of the ligands
and enable the cells to become more or less responsive to their microenvironment.
They are also involved in the maintenance of cell morphology. For example, if
syndecans are not expressed in epithelial cells, then the cells become rounded in
shape.
At present, four members of this family have been identified.
Syndecan-1, the most prevalent of the group, is expressed predominantly in epithelial
tissues.
Syndecan-2 predominates in tissues rich in endothelial cells.
4. Syndecan-3 is found primarily in neural tissues.
Syndecan-4 mainly in the liver and kidney.)
Bell Stage: enamel organ continues to enlarge and takes on a bell shaped appearance.
Four different types of cells can be distinguished on light microscopic examination.
Inner enamel epithelium – it consists of a single layer of cells that differentiate into
tall columnar ameloblasts. The cells of IEE exert an organizing influence on the
underlying mesenchymal cells in the dental papilla, which later differentiate into
odontoblasts.
Outer enamel epithelium – the cells are low cuboidal. During the formation of enamel,
the OEE is laid in folds. Between the folds, the adjacent mesenchyme of the dental sac
forms papillae that contain capillary loops and thus provide a rich nutritional supply
for the avascular enamel organ.
Stratum intermedium – a few layers of squamous cells between IEE and stellate
reticulum. Essential for enamel formation.
Stellate reticulum – the cells are star shaped with long processes and intercellular
fluid. The layer collapses before enamel formation to reduce the distance between
ameloblasts and the nutrient capillaries near OEE.
Advanced bell stage: formation of future DEJ – the boundary between the IEE and the
odontoblasts – membrana preformativa. The cervical loop of enamel organ gives rise
to HERS.
5. Development of periodontium
Mesenchyme deriving periodontium has two compartments:
1. Alveolar clade: fibroblasts, osteoblasts
2. Cement clade: fibroblasts, cementoblasts
Dental follicle (dental sac) gives rise to cementum, periodontal ligament and the
alveolar bone.
Dental follicle anatomically consists of dental follicle proper, perifollicular
mesenchyme.
6. Dental follicle proper: well defined band of cells juxtaposed to the dental papilla and
the convex outer surface
CEMENTUM
The cementum is a specialized mineralized tissue covering the root surfaces. After
enamel & dentin formation has reached the future CEJ, enamel organ forms the
Hertwig’s epithelial root sheath (HERS). HERS consists of the outer and inner enamel
epithelia. The structural continuity of HERS is lost once there is differentiation of
radicular cells into odontoblasts & first layer of root dentin is laid. The remnants of
HERS persist as cell rests of Malassez which are found in the periodontal ligament of
erupted teeth.
The intact epithelial sheath is located between the dental papilla and the dental follicle
proper. Cells of the dental follicle proper project cytoplasmic processes from their
leading edge towards and into the intercellular space between the root sheath cells.
These cells are identified as precementoblasts. The unidirectional migration of
precementoblasts towards the predentin surface appears to contribute to the breakup of
the root sheath and the formation of Sharpey’s fibres. Upon contact with the predentin
surface, the elongated precementoblasts become cuboidal in shape and differentiate
into cementoblasts.
Following a brief period of cementogenesis, the cementoblasts appear to detach from
the newly formed cementum surface and join the fibroblast population in the
periodontal ligament.
Primary cementum formation
Once differentiated, the cementoblasts deposit collagen fibrils at right angles to the
root surface so that the root has a series of fine collagen fibrils attached to it. The
7. cementoblasts then migrate away but continue to deposit collagen so that the fine fiber
bundles not only lengthen to maintain a fibrous fringe on the root surface, but also
thicken to form the fibrous matrix of acellular cementum. Cementoblasts also secrete
non collagenous proteins such as bone sialoprotein and osteocalcin.
This first formed cementum is acellular, as the cells that form it remain on its surface;
develops relatively slowly as the tooth is erupting; and covers atleast the coronal two
thirds of the root. First formed cementum thus consists of a mineralized layer with a
fibrous fringe attached to it. This continues until the forming periodontal ligament
fiber bundles become attached to the fibrous fringe. No surface layer of unmineralized
matrix is associated with acellular cementum.
Secondary cementum formation
Once the tooth is in occlusion, a more rapidly formed and less mineralized form of
cementum is deposited around the apical third of the root. Cementoblasts become
trapped in the matrix they are forming to occupy lacunae, and the cells become
cementocytes.
Five major types of cementum – Schroeder 1992
1. Acellular intrinsic fiber cementum
2. Acellular extrinsic fiber cementum
3. Cellular intrinsic fiber cementum
4. Cellular mixed fiber cementum
5. Acellular afibrillar cementum
8. Acellular intrinsic fiber cementum
First formed cementum as a result of cementoblastic activity and is elaborated before
the periodontal ligament forms, therefore the collagen is intrinsic. During
cementogenesis, osteopontin is prominent in intrinsic fiber cementum.
Acellular extrinsic fiber cementum
Once the PDL fiber bundles are formed and get connected to fibrous fringe bundles of
the acellular intrinsic fiber cementum, further deposition of mineral about and within
the bundles results in the formation of acellular extrinsic fiber cementum. It is made
up of a particular class of fibroblasts that are alkaline phosphatase positive.
Cellular intrinsic fiber cementum
The cells forming this cementum resemble the bone-forming cells. When first
deposited, the periodontal ligament is unorganized, the cementoblasts deposit the
organic matrix directly onto the root surface. No evidence of insertion of the sharpey’s
fibers. It is commonly associated with the healing of root fractures and repair of
resorptive defects.
Cellular mixed fiber cementum
It consists of intrinsic collagen fibers produced by the cementoblasts and some
extrinsic sharpey’s fibers.
Acellular afibrillar cementum
It is limited to the enamel surface and appears as cemental spurs or cemental islands
on the crowns of erupted teeth. It represents aberration where, a part of REE
disaggregates and the cells of dental follicle interact with the exposed enamel matrix,
leading to cementum deposition.
9. PERIODONTAL LIGAMENT
The development of periodontal ligament begins with root formation prior to tooth
eruption.
The mesenchymal cells of perifollicular region attain polarity, increased cellular
volume and synthetic activity. They become elongated. There is an increase in RER,
mitochondria and active golgi complex which synthesize collagen fibrils and
glycoprotein.
Principal fibers
The development of the major collagen bundles, the principle fibers of the periodontal
ligament, is closely related to root formation.
Fiber bundles originate at the surface of the newly formed root dentin in close relation
to elongated and highly polarized fibroblasts. The fringe fibers are tightly packed by
the action of cementoblasts. As the periodontal ligament matures, the fringe fibers
merge across the width of the ligament to form the principle fiber bundles. During the
development of the fringe fibers, fibroblasts exhibit cytoplasmic polarity towards the
root and alveolar bone surfaces. A specific cementum attachment protein favours the
PDL fibroblast attachment to the cementum surface.
10. With continued development of the root, the principle fibres are established as
continuous structures embedded as Sharpey’s fibers in bone and cementum.
The figure illustrating the development of principle fibres of periodontal ligament.
Bone Cementum
m
1. First, small, fine, brush- like fibrils --- root cementum
projecting into periodontal ligament space. From the
surface of the bone: small number of radiating, thin
collagen fibrils project into the periodontal ligament
space.
2 & 3. The number and thickness of the fibers entering the
bone increase. The fibers entering the bone are also longer
while those entering the cementum are still short.
4. The fibers entering the cementum increase in length and
thickness and fuse with fibres originating from the alveolar
bone in the periodontal ligament space.
(intermediate zone)
Bone Cementum
m
11. Oxytalan fibers: These are demonstrated in connective tissues destined to become
PDL when about 2mm of dentin is formed in the developing root.
They increase in size and rearrange themselves with further root development
Cells: The cells of the periodontal ligament are fibroblasts, osteoblasts, cementoblasts,
cementoclasts, and epithelial cells.
Viable cells are required for tooth movement.
1. Fibroblasts: These are the principle cells and most abundant cells in the
periodontal ligament and metabolize the extra cellular matrix components.
Fibroblasts help in remodelling: both synthesize & degrade collagen.
Subpopulation of osteoblast- like fibroblasts: these form bone cells &
cementoblasts, and are rich in alkaline phosphatase. They help in the
production of Acellular extrinsic fiber cementum.
2. Epithelial cells: Remnants of HERS, close to the cemental surface. These are
the Rests of Malassez.
3. The developing periodontal ligament consists of undifferentiated mesenchymal
cells or progenitor cells that retain the ability to differentiate into osteoblasts,
cementoblasts and fibroblasts.
4. Bone and cementum cells: Although technically situated in the PDL, bone and
cementum cells are properly associated with the hard tissues they form.
Development of neurovascular elements
In the early bell stage: rich innervation associated with small blood vessels is found in
the inner investing layer of dental follicle. As the root formation continues and the
tooth erupts, nerves grow into periodontal ligament. Vasculature is derived from the
networks associated with enamel organ & alveolar mucosa, vessels spread apically to
supply PDL.
12. GINGIVA
It is that part of the oral mucosa that covers the alveolar process of the jaws and
surrounds the necks of the teeth.
It comprises gingival epithelial and connective tissue. The epithelial component shows
regional morphological variations that include oral gingival epithelium, oral sulcular
epithelium and junctional epithelium.
The gingiva evolves as the crown enters the oral cavity by breaking through the oral
epithelium.
Development
The crown of the tooth is covered by a double layer of epithelial cells at the time it
begins its eruptive movements.
1. Those cells in contact with the enamel are the ameloblasts, which, having
completed their formative function, become firmly attached to the enamel
surface.
2. The outer layer consists of more flattened cells, the remnants of all the
remaining layers of the dental organ.
The above two layers of cells, together are called the reduced enamel epithelium.
Between the REE and the overlying oral epithelium is connective tissue that supports
both the REE and the oral epithelium.
When tooth eruption begins, this connective tissue breaks down. In response to the
degenerative changes occurring in the connective tissue, the cells of the outer layer of
the reduced enamel epithelium and the basal cells of the oral epithelium proliferate
and migrate into the degenerating connective tissue and eventually fuse to establish a
mass of epithelial cells over the erupting tooth. Cell death at the middle of this
RE
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13. epithelial plug leads to the formation of an epithelium- lined canal through which the
tooth erupts without hemorrhage.
From this mass of epithelium, the epithelial cuff, together with the remaining REE, the
epithelial component of the dentogingival junction is established. Once the tip of the
cusp of the erupting tooth emerges into the oral cavity, oral epithelial cells begin to
migrate partially over the REE in an apical direction. The attachment of the gingival
epithelium to tooth is maintained through the reduced ameloblasts and their hemi
desmosomes and basal lamina adjacent to the enamel surface. This is the primary
epithelial attachment.
The REE transforms gradually to become Junctional epithelium. The reduced
ameloblasts change their morphology and are transformed into squamous epithelial
cells that retain their attachment to the enamel surface. The cells of the outer layer of
the REE retain their ability to divide continuously to become and function as basal
cells of the forming Junctional epithelium. The transformed ameloblasts are
eventually displaced by the mitotic activity of these basal cells.
Meanwhile, the cells of the epithelial cuff stratify separating the cells of transformed
dental epithelium from the nutritive supply, resulting in the degenerating of latter cells
creating a gingival sulcus. The final conversion of the REE to JE may not occur until
3- 4 years after the tooth has erupted. Thus the epithelial component of the
dentogingival junction is formed, the JE from REE and the sulcular epithelium from
epithelial cuff. The JE derived from dental epithelium is eventually replaced by JE
formed from oral epithelial cells.
Development of gingival connective tissue
Gingival connective tissue fibroblasts originate from perifollicular mesenchyme.
During normal development, gingival fibroblasts do not come into contact with the
tooth surface. Gingival collagen turns over more rapidly than that of skin and bone,
but slower than that of periodontal ligament. The collagen matrix of gingival
connective tissue is well organized into fiber bundles.
14. ALVEOLAR BONE
Alveolar bone proper
• Late bell stage: bony septa, bony bridges- clearly outlined bony compartments
around tooth germs.
• Bony compartments + tooth germ: bodily movements to adjust to growing jaws
– minor bone remodeling
• Major changes: root development & eruption
• Cells of dental follicle– osteoblasts – alveolar bone proper
• Size and shape of individual tooth roots determine overall structure
• Insertion of sharpey’s fibers
• Rest of the bony structures: periosteal bone formation
Remodeling
• At root formation: Alveolar process is over the occlusal plane of tooth.
• Tooth eruption: remodeling
• Gubernacular canal
• New bone at base of bony crypt
15. EPITHELIAL MESENCHYMAL TISSUE INTERACTIONS
General features
Tissue morphology and phenotype are controlled by a complex interplay between
tissues of ectodermal and mesodermal origin. The interactions are controlled through
secreted products released from cells residing within both of these tissues and are
regulated via the genetic code of these cells.
Spemann (1938) demonstrated that for organogenesis to proceed, some form of
communication between the epithelial and mesenchymal tissues was required. This
interaction was called secondary embryonic induction and was shown to regulate
morphogenesis and cell differentiation.
The following are some examples that provide useful insight into the development of
teeth.
1. If epithelium from a developing tooth bud site is placed onto mesenchyme
distant from the dental arch, no tooth formation results.
2. If epithelium from a site that normally does not produce teeth is layered over
mesenchyme from the dental arch, then normal tooth bud formation occurs.
3. If epithelium from a developing tooth bud site is placed over the connective
tissue derived from the neural crest, then tooth development progresses.
These findings indicate that in undifferentiated tissues (such as neural crest cells)
the epithelium has an instructive component leading to the development of the
ectomesenchyme. Once this differentiation process has been initiated, the
ectomesenchyme adopts the dominant role in epithelial- mesenchymal interactions.
16. Once the enamel organ has formed during tooth development, the cells of the inner
enamel epithelium induce the adjacent cells in the dental papilla to differentiate
into odontoblasts: epithelium influencing mesenchyme.
Genetic features
The pathway of initiation, morphogenesis, and differentiation involves the production
of molecular signals via the initiation of gene expression.
Genetic codes for signaling mechanisms—instruct cells leading to organ development
E.g. transcription factors: these are nuclear proteins that bind to DNA and control the
expression of other genes.
Homeobox (Hox) genes: specify spatial location of future tooth germs.
Dlx-1 & 2 is noted in areas of epithelial thickening.
Molecular features
Following gene expression, locally secreted molecules control cell differentiation &
organ development.
Growth factors, cell surface glycoproteins, components of extracellular matrix appear
to be prime candidates for governing developmental processes. These exert their
influence on cells via specific cell surface receptors
During odontogenesis, BMPs, TGF- ß, FGF (fibroblast growth factor) have been
found to be differentially expressed according to the stage of development,
morphogenesis and cell differentiation.
Other growth factors including PDGF, EGF and growth hormone have been
associated with different stages of tooth development.
TGF- ß1 is first seen in the epithelial thickenings that dictate sites of developing teeth.
Shortly after this it is expressed in the underlying mesenchyme.
17. BMP-2, BMP-4 -- Budding epithelium....Mesenchyme.
FGF-3
FGF-4
Extracellular matrix
Components of extracellular matrix and cell surface--- instructional effect on cells
18. Initiated from mesenchymal cells---- influence ectodermal tissues
Tenascin : condensing mesenchyme of dental papilla
Tenascin, fibronectin --- bell stage --- odontoblast differentiation.
Syndecan – 1 --- early bud stage through cap stage --- condensing mesenchyme of
dental papilla
Decreases during transition from cap to bell
EGF – high in epithelium in bud stage, shifts to mesenchyme in bell stage.
Summary
The development of periodontal tissues involves both ectodermal and mesenchymal
tissues.
A good understanding of the principles of formation of periodontal structures is
essential for unraveling the mechanisms associated with tissue regeneration.
The clinical ramifications lie in the regulatory mechanisms governing the correct
expression of epithelial & connective tissue components during regeneration and r.
repair.