Growth and development involves complex interactions between tissues originating from the three germ layers - ectoderm, endoderm, and mesoderm. Specific structures in the craniofacial complex are derived from unique combinations of these tissues. Growth patterns in the fetus and after birth follow cephalocaudal and proportional gradients. Tissue systems grow at different rates over the lifespan from early fetal development through maturity.
The document summarizes key aspects of oral mucosa development and structure. It describes that the oral mucosa lines the oral cavity and has different types (masticatory, lining, specialized) according to function. The mucosa develops from the primitive oral cavity and includes structures from branchial arches. It matures through specific stages in utero, developing characteristic features like papillae. The mucosa has stratified squamous epithelium and contains minor salivary glands. It has specialized junctions like desmosomes that maintain the epithelial barrier and allow cell renewal processes.
The document discusses the peridontium and its components, which include the gingiva, periodontal ligament, cementum, and alveolar bone. It focuses on cementum, describing it as a hard connective tissue that covers tooth roots and provides attachment for collagen fibers. Cementum begins forming at the cementoenamel junction and continues to the root apex. It contains cementoblasts and cementocytes that aid in its formation and structure. Cementum comes in cellular and acellular varieties and demonstrates incremental lines from its continuous deposition over time.
This document discusses the structure and properties of enamel. It begins by defining enamel as the outermost layer of tooth covering made of highly mineralized tissue. The structure of enamel is described including enamel rods, interrod substance, and rod sheaths. Physical properties like hardness, thickness and chemical composition consisting mainly of hydroxyapatite are covered. Incremental growth lines including cross striations, striae of Retzius and neonatal line are also summarized. Hypo-mineralized enamel structures such as enamel spindles, tufts and lamellae are defined. Finally, the surface structure of enamel including outer structureless enamel and perikymata grooves are described.
The development of teeth (odontogenesis) is a complex process where teeth form from embryonic cells and grow and erupt into the oral cavity. It begins around the 6th week of gestation with the formation of the primary epithelial band in the upper and lower jaws, from which the dental lamina develops and projects into the underlying mesenchyme to form tooth buds. These buds develop through the bud, cap, and bell stages to form the crown and root structures. Various cell types differentiate and interact to form enamel, dentin, cementum, and the periodontium. Root formation occurs after crown formation is complete, guided by Hertwig's epithelial root sheath which determines the root shape. Teeth continue developing and
The periodontal ligament is a dense fibrous tissue that connects teeth to the alveolar bone. It is composed primarily of collagen fibers arranged in bundles and a ground substance containing cells, blood vessels and nerves. The collagen fibers provide structural support and allow the teeth to withstand functional forces. Fibroblasts are the main cell type and are responsible for collagen synthesis and remodeling. Blood vessels supply the ligament with nutrients. The periodontal ligament functions to attach teeth to the alveolar bone and helps maintain the teeth in their proper functional positions.
Alveolar bone is the specialized bone that forms the sockets for teeth in the maxilla and mandible. It consists of alveolar bone proper surrounding the tooth root, supporting alveolar bone made of cortical plates and spongy bone, and bundle bone where periodontal ligament fibers insert. Osteoblasts build bone matrix while osteoclasts resorb it, allowing remodeling. With age, alveolar bone thins with wider marrow spaces and more fragile trabeculae, leading the alveolar crest to slope down distally as teeth tilt mesially.
This document provides information on cementum, including its definition, physical characteristics, chemical composition, formation (cementogenesis), classification, functions, anomalies, and clinical considerations. Cementum is the mineralized tissue covering tooth roots. It is softer than dentin and lacks enamel's luster. Cementum formation involves acellular and cellular stages. Cementum attaches the periodontal ligament fibers to the tooth root and allows for tooth repair. Abnormalities include hypercementosis, ankylosis, and cementomas. Cementum is an important part of the periodontium that aids in tooth attachment and repair.
The document summarizes key aspects of oral mucosa development and structure. It describes that the oral mucosa lines the oral cavity and has different types (masticatory, lining, specialized) according to function. The mucosa develops from the primitive oral cavity and includes structures from branchial arches. It matures through specific stages in utero, developing characteristic features like papillae. The mucosa has stratified squamous epithelium and contains minor salivary glands. It has specialized junctions like desmosomes that maintain the epithelial barrier and allow cell renewal processes.
The document discusses the peridontium and its components, which include the gingiva, periodontal ligament, cementum, and alveolar bone. It focuses on cementum, describing it as a hard connective tissue that covers tooth roots and provides attachment for collagen fibers. Cementum begins forming at the cementoenamel junction and continues to the root apex. It contains cementoblasts and cementocytes that aid in its formation and structure. Cementum comes in cellular and acellular varieties and demonstrates incremental lines from its continuous deposition over time.
This document discusses the structure and properties of enamel. It begins by defining enamel as the outermost layer of tooth covering made of highly mineralized tissue. The structure of enamel is described including enamel rods, interrod substance, and rod sheaths. Physical properties like hardness, thickness and chemical composition consisting mainly of hydroxyapatite are covered. Incremental growth lines including cross striations, striae of Retzius and neonatal line are also summarized. Hypo-mineralized enamel structures such as enamel spindles, tufts and lamellae are defined. Finally, the surface structure of enamel including outer structureless enamel and perikymata grooves are described.
The development of teeth (odontogenesis) is a complex process where teeth form from embryonic cells and grow and erupt into the oral cavity. It begins around the 6th week of gestation with the formation of the primary epithelial band in the upper and lower jaws, from which the dental lamina develops and projects into the underlying mesenchyme to form tooth buds. These buds develop through the bud, cap, and bell stages to form the crown and root structures. Various cell types differentiate and interact to form enamel, dentin, cementum, and the periodontium. Root formation occurs after crown formation is complete, guided by Hertwig's epithelial root sheath which determines the root shape. Teeth continue developing and
The periodontal ligament is a dense fibrous tissue that connects teeth to the alveolar bone. It is composed primarily of collagen fibers arranged in bundles and a ground substance containing cells, blood vessels and nerves. The collagen fibers provide structural support and allow the teeth to withstand functional forces. Fibroblasts are the main cell type and are responsible for collagen synthesis and remodeling. Blood vessels supply the ligament with nutrients. The periodontal ligament functions to attach teeth to the alveolar bone and helps maintain the teeth in their proper functional positions.
Alveolar bone is the specialized bone that forms the sockets for teeth in the maxilla and mandible. It consists of alveolar bone proper surrounding the tooth root, supporting alveolar bone made of cortical plates and spongy bone, and bundle bone where periodontal ligament fibers insert. Osteoblasts build bone matrix while osteoclasts resorb it, allowing remodeling. With age, alveolar bone thins with wider marrow spaces and more fragile trabeculae, leading the alveolar crest to slope down distally as teeth tilt mesially.
This document provides information on cementum, including its definition, physical characteristics, chemical composition, formation (cementogenesis), classification, functions, anomalies, and clinical considerations. Cementum is the mineralized tissue covering tooth roots. It is softer than dentin and lacks enamel's luster. Cementum formation involves acellular and cellular stages. Cementum attaches the periodontal ligament fibers to the tooth root and allows for tooth repair. Abnormalities include hypercementosis, ankylosis, and cementomas. Cementum is an important part of the periodontium that aids in tooth attachment and repair.
There are four types of dentin that form in teeth:
1) Mantle dentin is the first layer formed around the dental pulp, consisting of loosely arranged collagen fibers.
2) Primary dentin is laid down beneath the mantle dentin as odontoblasts increase in size and collagen is more tightly packed.
3) Secondary dentin forms more slowly throughout life after root formation is complete.
4) Tertiary dentin is deposited in response to stimuli like attrition or decay, forming reactionary or reparative dentin to protect the pulp.
The document discusses the anatomical features of the maxillary first and second premolars.
- The maxillary first premolar typically has two roots, a mesial marginal groove, and a hexagonal occlusal outline. In contrast, the maxillary second premolar usually has a single root, lacks a mesial groove, and has a more oval occlusal outline.
- Other distinguishing features include the lingual cusp being shorter than the buccal cusp in the first premolar but equal in height in the second premolar. The second premolar also exhibits more supplemental occlusal grooves.
The document summarizes the development and growth process of teeth. It begins with the formation of the primitive oral cavity and buccopharyngeal membrane. It then discusses the development of the primary epithelial band and dental lamina. The key stages of tooth development are described - the bud stage, cap stage, bell stage, and root formation stage. The roles of the enamel organ, dental papilla, dental sac, and Hertwig's epithelial root sheath in determining tooth shape and root development are also summarized.
Enamel is formed through the process of amelogenesis, which involves the life cycle of ameloblasts. Ameloblasts undergo morphological and physiological changes during the secretory, transitional, and maturative stages of amelogenesis. During the secretory stage, ameloblasts develop Tomes' processes which extend into the enamel matrix and help establish the rod and interrod structure of enamel. As enamel matures, ameloblasts transition to having microvilli and modulate between ruffled and smooth shapes to both remove organic material from the enamel and introduce inorganic minerals to fully mineralize the enamel.
Cementum is the mineralized tissue covering the roots of teeth that provides attachment for collagen fibers linking the tooth to surrounding bone. It begins at the cementoenamel junction and continues along the root to the apex. Cementum is avascular and less hard than dentin. It contains both inorganic minerals and organic materials including collagen. Cementoblast cells synthesize cementum by laying down an organic matrix that subsequently mineralizes. Cementum thickness varies along the root and increases with age. It provides for functional adaptation and resistance to resorption during orthodontic tooth movement.
The document summarizes key aspects of the periodontium, including its components of cementum, periodontal ligament, and alveolar bone. It describes in detail the types of cementum (acellular extrinsic fiber, cellular intrinsic fiber, acellular afibrillar), their formation processes, composition and roles in tooth attachment. Factors regulating cementogenesis like growth factors, collagens and signaling molecules are also discussed. The aging changes and clinical correlations of cementum are presented.
Dental anatomy introduction for BDS first year studentsmadhusudhan reddy
This document provides an introduction to dental terminology and anatomy. It defines important terms like midline, quadrants, occlusion, dentition and classifications of teeth. Key anatomical structures of teeth are described such as the crown, root, enamel, dentin, cementum, pulp and surrounding structures. Common terminology for surfaces, angles, depressions and elevations of teeth are introduced. The dental formulae and eruption patterns of primary and permanent teeth are outlined. Different tooth numbering systems are also explained.
This document discusses tooth shedding, or the process by which primary teeth are replaced by permanent teeth. It defines shedding as the physiological process by which deciduous teeth are resorbed and lost to make way for successor teeth. Key points covered include the factors affecting shedding like pressure from erupting permanent teeth and genetic factors; the histology of shedding involving resorption of dental hard and soft tissues; the typical pattern of shedding from anterior to posterior teeth; and potential abnormalities in shedding like retained, submerged, or residual primary teeth.
This document discusses the process of shedding deciduous teeth. It begins by defining shedding as the physiological process by which deciduous teeth are eliminated to allow for eruption of permanent successors. It then describes how deciduous teeth cannot withstand jaw growth or increased forces of mastication from muscles, requiring their replacement. The shedding process involves progressive root resorption by multinucleated cells called odontoclasts, similar to osteoclasts. As permanent teeth erupt, they apply pressure leading to bone and root resorption and degradation of the periodontal ligament until the deciduous tooth is shed.
Aging causes irreversible changes to the dental hard tissues over time. The three main tissues - enamel, dentin, and cementum - all undergo changes as part of the aging process. Enamel becomes less permeable and more discolored with age. Dentin develops more dead tracts and sclerotic dentin. Cementum may experience hypercementosis and the formation of cementicles. The alveolar bone also undergoes resorption, decreasing in height and width over time. These morphological and functional changes to the dental tissues are a natural part of the biological aging process.
1. Tooth development begins around the 6th week of gestation with the formation of the primary epithelial band, which divides into the dental lamina and vestibular lamina.
2. Teeth develop through a series of stages from bud to bell shaped to advanced bell stage when mineralization begins and root formation commences.
3. The dental lamina gives rise to the tooth buds and plays a role in shaping tooth development through later stages. The enamel organ and dental papilla are structures that form within the developing tooth bud.
The document summarizes the structure and composition of dentin. It discusses the different types of dentin - primary, secondary, tertiary - and their locations and functions. It also describes odontoblasts, the cells responsible for dentin formation, and dentinal tubules, the structures that span the thickness of dentin.
This document discusses the stages of amelogenesis, the formation of enamel. It describes 6 stages: 1) morphogenic, 2) differentiating, 3) secretory, 4) maturative, 5) protective, and 6) desmolytic. During the secretory stage, ameloblasts secrete enamel matrix proteins and form Tomes' processes to deposit the matrix along the developing enamel surface. In the maturative stage, ameloblasts engulf the matrix and facilitate its mineralization into mature enamel. The protective stage involves deposition of an enamel cuticle, while in the desmolytic stage, the reduced enamel epithelium aids in tooth eruption.
1. Tooth development involves interactions between the oral epithelium and underlying neural crest-derived ectomesenchyme. Molecules and signaling pathways initiate differentiation and morphogenesis of teeth.
2. Neural crest cells constitute much of the mesenchyme of the head and neck, including the connective tissues of dental structures. These ectomesenchymal cells instruct the overlying oral epithelium to begin tooth development.
3. Tooth development proceeds through bud, cap, and bell stages as the enamel organ invaginates and proliferates. Key events include formation of the enamel knot and cord which help pattern the crown, and differentiation of preameloblasts and odontoblasts which begin secre
This document provides information on cementum, which is the mineralized tissue covering the roots of teeth. It begins at the cemento-enamel junction and extends to the root apex. There are different types of cementum based on cellularity and the presence of fibers, including acellular, cellular, and intermediate cementum. Cementum is composed of collagen fibers, ground substance, and may contain cementocytes. It provides various functions such as attachment of periodontal ligament fibers and protection of the tooth root.
Histology of oral mucous membrane including gingiva/certified fixed orthodon...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The document summarizes the process of dentinogenesis or dentin formation. It involves differentiation of odontoblasts from dental papilla cells, secretion of an organic matrix, and mineralization of the matrix. Odontoblasts secrete collagen fibers and matrix vesicles that initiate mineralization. Dentin is formed in mantle dentin near enamel and circumpulpal dentin further inside via continuous mineralization. Root dentin formation begins after crown completion, guided by Hertwig's epithelial root sheath.
This document discusses the morphology and features of the maxillary second premolar tooth. It provides details on:
1. The maxillary second premolar's eruption timeline and root development stages.
2. The geometric outlines, outlines of cusps and ridges, contact areas, surface anatomy, cervical lines, and roots for the labial, lingual, mesial, distal, and occlusal aspects of the tooth.
3. A comparison of the features of the maxillary first and second premolars, highlighting differences in their outlines, cusps, contact areas, surface anatomy, roots, and occlusal depressions and elevations.
During the third to eighth week embryonic period (also called the period of organogenesis):
- Each of the three germ layers (ectoderm, mesoderm, endoderm) gives rise to specific tissues and organs.
- By the end of this period, the main organ systems have been established and the external body form is recognizable.
- The ectoderm gives rise to the central nervous system, peripheral nervous system, neural crest derivatives, sensory epithelium of ears/eyes, epidermis, and other structures. The mesoderm gives rise to supporting tissues, muscles, blood and lymph cells, kidneys, gonads, and other structures.
This document discusses embryology and the development of the musculoskeletal system. It covers the following key points:
1. Embryology is the study of developmental events during prenatal stages, specifically the embryonic and fetal periods. The embryonic period is the first 8 weeks when the basic body plan takes shape, and the fetal period is the remaining 30 weeks when structures continue growing.
2. Musculoskeletal development begins with the formation of somites from paraxial mesoderm, which give rise to bones, cartilage, and muscles. Bones develop through membranous or endochondral ossification. Long bones are examples of endochondral ossification, forming cartilage models that are later replaced with bone.
3. Lim
There are four types of dentin that form in teeth:
1) Mantle dentin is the first layer formed around the dental pulp, consisting of loosely arranged collagen fibers.
2) Primary dentin is laid down beneath the mantle dentin as odontoblasts increase in size and collagen is more tightly packed.
3) Secondary dentin forms more slowly throughout life after root formation is complete.
4) Tertiary dentin is deposited in response to stimuli like attrition or decay, forming reactionary or reparative dentin to protect the pulp.
The document discusses the anatomical features of the maxillary first and second premolars.
- The maxillary first premolar typically has two roots, a mesial marginal groove, and a hexagonal occlusal outline. In contrast, the maxillary second premolar usually has a single root, lacks a mesial groove, and has a more oval occlusal outline.
- Other distinguishing features include the lingual cusp being shorter than the buccal cusp in the first premolar but equal in height in the second premolar. The second premolar also exhibits more supplemental occlusal grooves.
The document summarizes the development and growth process of teeth. It begins with the formation of the primitive oral cavity and buccopharyngeal membrane. It then discusses the development of the primary epithelial band and dental lamina. The key stages of tooth development are described - the bud stage, cap stage, bell stage, and root formation stage. The roles of the enamel organ, dental papilla, dental sac, and Hertwig's epithelial root sheath in determining tooth shape and root development are also summarized.
Enamel is formed through the process of amelogenesis, which involves the life cycle of ameloblasts. Ameloblasts undergo morphological and physiological changes during the secretory, transitional, and maturative stages of amelogenesis. During the secretory stage, ameloblasts develop Tomes' processes which extend into the enamel matrix and help establish the rod and interrod structure of enamel. As enamel matures, ameloblasts transition to having microvilli and modulate between ruffled and smooth shapes to both remove organic material from the enamel and introduce inorganic minerals to fully mineralize the enamel.
Cementum is the mineralized tissue covering the roots of teeth that provides attachment for collagen fibers linking the tooth to surrounding bone. It begins at the cementoenamel junction and continues along the root to the apex. Cementum is avascular and less hard than dentin. It contains both inorganic minerals and organic materials including collagen. Cementoblast cells synthesize cementum by laying down an organic matrix that subsequently mineralizes. Cementum thickness varies along the root and increases with age. It provides for functional adaptation and resistance to resorption during orthodontic tooth movement.
The document summarizes key aspects of the periodontium, including its components of cementum, periodontal ligament, and alveolar bone. It describes in detail the types of cementum (acellular extrinsic fiber, cellular intrinsic fiber, acellular afibrillar), their formation processes, composition and roles in tooth attachment. Factors regulating cementogenesis like growth factors, collagens and signaling molecules are also discussed. The aging changes and clinical correlations of cementum are presented.
Dental anatomy introduction for BDS first year studentsmadhusudhan reddy
This document provides an introduction to dental terminology and anatomy. It defines important terms like midline, quadrants, occlusion, dentition and classifications of teeth. Key anatomical structures of teeth are described such as the crown, root, enamel, dentin, cementum, pulp and surrounding structures. Common terminology for surfaces, angles, depressions and elevations of teeth are introduced. The dental formulae and eruption patterns of primary and permanent teeth are outlined. Different tooth numbering systems are also explained.
This document discusses tooth shedding, or the process by which primary teeth are replaced by permanent teeth. It defines shedding as the physiological process by which deciduous teeth are resorbed and lost to make way for successor teeth. Key points covered include the factors affecting shedding like pressure from erupting permanent teeth and genetic factors; the histology of shedding involving resorption of dental hard and soft tissues; the typical pattern of shedding from anterior to posterior teeth; and potential abnormalities in shedding like retained, submerged, or residual primary teeth.
This document discusses the process of shedding deciduous teeth. It begins by defining shedding as the physiological process by which deciduous teeth are eliminated to allow for eruption of permanent successors. It then describes how deciduous teeth cannot withstand jaw growth or increased forces of mastication from muscles, requiring their replacement. The shedding process involves progressive root resorption by multinucleated cells called odontoclasts, similar to osteoclasts. As permanent teeth erupt, they apply pressure leading to bone and root resorption and degradation of the periodontal ligament until the deciduous tooth is shed.
Aging causes irreversible changes to the dental hard tissues over time. The three main tissues - enamel, dentin, and cementum - all undergo changes as part of the aging process. Enamel becomes less permeable and more discolored with age. Dentin develops more dead tracts and sclerotic dentin. Cementum may experience hypercementosis and the formation of cementicles. The alveolar bone also undergoes resorption, decreasing in height and width over time. These morphological and functional changes to the dental tissues are a natural part of the biological aging process.
1. Tooth development begins around the 6th week of gestation with the formation of the primary epithelial band, which divides into the dental lamina and vestibular lamina.
2. Teeth develop through a series of stages from bud to bell shaped to advanced bell stage when mineralization begins and root formation commences.
3. The dental lamina gives rise to the tooth buds and plays a role in shaping tooth development through later stages. The enamel organ and dental papilla are structures that form within the developing tooth bud.
The document summarizes the structure and composition of dentin. It discusses the different types of dentin - primary, secondary, tertiary - and their locations and functions. It also describes odontoblasts, the cells responsible for dentin formation, and dentinal tubules, the structures that span the thickness of dentin.
This document discusses the stages of amelogenesis, the formation of enamel. It describes 6 stages: 1) morphogenic, 2) differentiating, 3) secretory, 4) maturative, 5) protective, and 6) desmolytic. During the secretory stage, ameloblasts secrete enamel matrix proteins and form Tomes' processes to deposit the matrix along the developing enamel surface. In the maturative stage, ameloblasts engulf the matrix and facilitate its mineralization into mature enamel. The protective stage involves deposition of an enamel cuticle, while in the desmolytic stage, the reduced enamel epithelium aids in tooth eruption.
1. Tooth development involves interactions between the oral epithelium and underlying neural crest-derived ectomesenchyme. Molecules and signaling pathways initiate differentiation and morphogenesis of teeth.
2. Neural crest cells constitute much of the mesenchyme of the head and neck, including the connective tissues of dental structures. These ectomesenchymal cells instruct the overlying oral epithelium to begin tooth development.
3. Tooth development proceeds through bud, cap, and bell stages as the enamel organ invaginates and proliferates. Key events include formation of the enamel knot and cord which help pattern the crown, and differentiation of preameloblasts and odontoblasts which begin secre
This document provides information on cementum, which is the mineralized tissue covering the roots of teeth. It begins at the cemento-enamel junction and extends to the root apex. There are different types of cementum based on cellularity and the presence of fibers, including acellular, cellular, and intermediate cementum. Cementum is composed of collagen fibers, ground substance, and may contain cementocytes. It provides various functions such as attachment of periodontal ligament fibers and protection of the tooth root.
Histology of oral mucous membrane including gingiva/certified fixed orthodon...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The document summarizes the process of dentinogenesis or dentin formation. It involves differentiation of odontoblasts from dental papilla cells, secretion of an organic matrix, and mineralization of the matrix. Odontoblasts secrete collagen fibers and matrix vesicles that initiate mineralization. Dentin is formed in mantle dentin near enamel and circumpulpal dentin further inside via continuous mineralization. Root dentin formation begins after crown completion, guided by Hertwig's epithelial root sheath.
This document discusses the morphology and features of the maxillary second premolar tooth. It provides details on:
1. The maxillary second premolar's eruption timeline and root development stages.
2. The geometric outlines, outlines of cusps and ridges, contact areas, surface anatomy, cervical lines, and roots for the labial, lingual, mesial, distal, and occlusal aspects of the tooth.
3. A comparison of the features of the maxillary first and second premolars, highlighting differences in their outlines, cusps, contact areas, surface anatomy, roots, and occlusal depressions and elevations.
During the third to eighth week embryonic period (also called the period of organogenesis):
- Each of the three germ layers (ectoderm, mesoderm, endoderm) gives rise to specific tissues and organs.
- By the end of this period, the main organ systems have been established and the external body form is recognizable.
- The ectoderm gives rise to the central nervous system, peripheral nervous system, neural crest derivatives, sensory epithelium of ears/eyes, epidermis, and other structures. The mesoderm gives rise to supporting tissues, muscles, blood and lymph cells, kidneys, gonads, and other structures.
This document discusses embryology and the development of the musculoskeletal system. It covers the following key points:
1. Embryology is the study of developmental events during prenatal stages, specifically the embryonic and fetal periods. The embryonic period is the first 8 weeks when the basic body plan takes shape, and the fetal period is the remaining 30 weeks when structures continue growing.
2. Musculoskeletal development begins with the formation of somites from paraxial mesoderm, which give rise to bones, cartilage, and muscles. Bones develop through membranous or endochondral ossification. Long bones are examples of endochondral ossification, forming cartilage models that are later replaced with bone.
3. Lim
This document discusses the development of the face and oral cavity from early embryonic stages through postnatal growth. It covers topics like germ cell formation and fertilization, the formation of the three germ layers and neural tube, development of the branchial arches and pharyngeal pouches, shifts in blood supply to the face, development of muscles and cartilage, and prenatal and postnatal growth patterns. The development of the face and oral cavity involves complex interactions between ectoderm, mesoderm, endoderm, and neural crest cells during embryonic and fetal development.
This document provides an overview of general embryology, including:
- The formation of the blastocyst from the morula, containing an inner cell mass and outer cell layer.
- How the three germ layers (ectoderm, mesoderm, endoderm) form and give rise to different tissues and organs.
- How the neural crest cells develop and migrate to form craniofacial structures like bone and connective tissue.
- The formation and role of the branchial arches and pouches in developing orofacial structures from the first, second, and third arches.
1. The primitive streak forms in the blastula and establishes bilateral symmetry and the site of gastrulation. It initiates formation of the three germ layers - ectoderm, endoderm, and mesoderm.
2. The notochord induces neural plate formation and provides organizational signals for head development. It lies along the embryo's axis and gives rise to the vertebral column.
3. Neural crest cells migrate extensively and give rise to many tissues, including those that form the skeleton and connective tissues of the head.
The document discusses human craniofacial development from conception through fetal stages. It covers the origin of the human embryo from fertilization, the formation of germ layers, development of branchial arches and clefts, and the differentiation of tissues and structures from the germ layers and arches in the lower, middle, and upper thirds of the face. Key topics include mesenchymal condensations that form the mandibular arch and maxillary processes, ossification centers of the maxilla, and cartilage contributions to mandibular growth.
This document summarizes the phases of embryonic development from weeks 4-8. It discusses that this is the period of organogenesis where major organs develop. It describes the three phases of development - growth, morphogenesis, and differentiation. It explains how the embryo folds in the median plane (head and tail folding) and horizontal plane (lateral folding). It lists the derivatives of the three germ layers - ectoderm, mesoderm, and endoderm - which give rise to all tissues and organs. In summary, this provides an overview of the key developmental processes and structures that form during this critical period of early human development.
Prenatal development of skeletal systemAhmed Hammad
- During the first trimester, the embryo forms three germ layers including the mesoderm which begins forming the foundation for bones. By week 9, bones start developing in the arms and legs.
- In the second trimester, bone tissue develops around the head by week 13. By week 15, the skeleton rapidly develops and grows, with the skull becoming more prominent.
- In the third trimester, most bones are developed although growth continues until birth, with the skeleton becoming harder in preparation for birth.
The skeletal and muscular systems develop from paraxial mesoderm, lateral plate mesoderm, and neural crest cells. Mesoderm forms somites that differentiate into sclerotome and dermomyotome, with sclerotome cells becoming mesenchyme that migrates and forms cartilage models through endochondral ossification or membraneous bone, while dermomyotome forms myoblasts that fuse into muscle fibers. Limb buds develop from lateral plate mesoderm and rotate as cartilage and bone form through endochondral ossification while surrounding musculature develops from dermomyotome and surrounding nerves
During the 3rd week of development, gastrulation occurs which involves the formation of the three germ layers - ectoderm, mesoderm, and endoderm. This transforms the bilaminar embryo into a trilaminar embryo with distinct layers. Neurulation also occurs, forming the neural tube which will later become the central nervous system. By the end of the 3rd week, the foundation is laid for all major organ systems as each germ layer gives rise to specific tissues and organs.
Development of oral cavity and face .ppt by dr. samidha aroraSamidha Arora
The document summarizes the development of the oral cavity and face from the 4th week of embryonic development. It discusses how the frontonasal process, nasal placodes, maxillary processes, and mandibular processes give rise to different structures of the face. It also describes the development of the palate from palatal shelves growing from the maxillary processes that later fuse together.
The embryonic stage occurs from 3-8 weeks of development. During this stage, the three germ layers (ectoderm, mesoderm, endoderm) give rise to major organ systems. By the end of the embryonic period, the main organ systems are established. The ectoderm forms the central nervous system and skin/hair/nails. Neural crest cells migrate from the ectoderm to form many structures. The mesoderm forms muscles, bones, and the circulatory system. The endoderm forms the lining of the digestive tract and respiratory system. Neurulation occurs during the third week, forming the neural tube which will become the brain and spinal cord.
Development of the musculoskeletal systemSahar Hafeez
The document summarizes the development of the musculoskeletal system from early embryonic stages. It discusses how the skeletal and muscular systems originate from mesoderm and the processes of ossification and myogenesis. Key events include the formation of somites which differentiate into sclerotome and dermomyotome, the development of limb buds and their rotation, and the segmentation of axial musculature into epimere and hypomere. The document provides an overview of the embryonic development of the skeletal and muscular systems.
Development of the musculoskeletal systemSahar Hafeez
In this presentation development of the Musculoskeletal system which is one of the largest systems of human body has been described. The viewer would be able to learn about the concept of Intrauterine bone formation in general and the role of embryonic connective tissue. Also, the origin of the two muscle groups of the , Extensors & Flexors along with their motor innervation pattern has been described in this presentation.
This document discusses embryonic and fetal development from 3-8 weeks (embryonic period) and 9 weeks to birth (fetal period). During the embryonic period, the three germ layers give rise to specific tissues and organs as the main organ systems are established. Neurulation occurs as the neural tube forms from the neural plate. Neural crest cells migrate throughout the body. The mesoderm forms somites which differentiate into muscle, bone and skin tissues. Blood islands form and later hematopoietic stem cells arise. The endoderm forms the gastrointestinal tract. During the fetal period, organs mature and the fetus grows rapidly in the third, fourth and fifth months.
The document summarizes the development of the face, paranasal sinuses, and associated structures from early embryonic development through the fetal period. It describes how the germ layers form and give rise to the ectoderm, endoderm, and mesoderm. It then explains how the pharyngeal arches develop and contribute to structures of the face, nose, mouth, and neck. It provides details on the development of specific structures including the lips, cheeks, nose, eyes, ears, palate, and paranasal sinuses. It also briefly mentions anomalies that can arise from abnormalities during development of each structure.
The document summarizes the development of the musculoskeletal system from mesenchymal tissues. It describes how:
1. Somites differentiate into sclerotome which forms bones and dermomyotome which forms muscles and dermis.
2. The skull develops from both endochondral and intramembranous ossification, with parts originating from neural crest and paraxial mesoderm.
3. The vertebral column develops through endochondral ossification, forming cartilage models that are later replaced with bone.
4. Ribs develop from costal processes of vertebrae, while the sternum develops from sternal bars.
5. Muscles develop from dermomyotome splitting
The document summarizes the development of the face from the 4th week of embryonic development. It discusses how the frontonasal process, maxillary processes, and mandibular processes form the structures of the face, including the lips, nose, eyes, ears, and palate. It also describes the development of branchial arches and how they contribute to specific muscles, nerves, arteries, and bones. The formation and differentiation of the pharyngeal pouches and clefts that form parts of the ear, thyroid, parathyroid glands and thymus are also outlined.
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There is increasing confidence that cell therapies will soon play a role in the treatment of autoimmune disorders, but the extent of this impact remains to be seen. Early readouts on autologous CAR-Ts in lupus are encouraging, but manufacturing and cost limitations are likely to restrict access to highly refractory patients. Allogeneic CAR-Ts have the potential to broaden access to earlier lines of treatment due to their inherent cost benefits, however they will need to demonstrate comparable or improved efficacy to established modalities.
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1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar lead (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
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Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. Chapter 3, Cardiology Explained, https://www.ncbi.nlm.nih.gov/books/NBK2214/
7. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
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3. Definition
Fundamentals of growth & development
• Prenatal Growth
• Postnatal Growth
Methods for studying physical growth
Genetic influences on growth
Nature of skeletal growth
Sites and Types of Growth in Craniofacial
Complex
Theories of Growth Control
Clinical considerations
4. Stewart (1982) : Developmental increase in mass
Profitt (1986) : Increase in size or number
Moyer (1988) : Changes in amount of living
substance
Moss () : Change in any morphological
parameter which is measurable
5. Todd (1931) : Increase in size
JS Huxley : Self multiplication of living
substance
Stedman (1990) : Increase in a size of a living
being or any of its parts, occuring in the
process of development
Pinkham (1994) : Growth signifies an increase,
expansion of any given tissue
6. Todd (1931) : Increase in complexity
Moyers (1988) : Naturally occuring unidirectional changes
in the life of an individual from its existence as a single cell
to its elaboration as a multifunctional unit terminating in
death
Pinkham (1994) : Development addresses the progressive
development of tissue
Enlow () : A maturational process involving progressive
differentiation at the cellular & tissue levels
7. Growth is basically an anatomic phenomenon &
quantitative in nature
Development is basically a physiologic
phenomenon & qualitative in nature
8. Prenatal growth
1) Period of ovum: From time of fertilization till 1 week
2) Period of embryo: 2-8 week
3) Period of fetus: 9th week onwards till birth
Postnatal growth
Maturity
Old age
9. • After fertilization of ovum, a series of cell divisions give rise
to an egg cell mass – MORULA
• Outer cell layer (trophoblast)
• Inner cell mass (embryoblast):
Epiblast embryo Hypoblast placenta
10. • Anterior end of primitive
streak ENDODERM
(lower germ layer)
• Perspective mesodermal cells
migrate from epiblast through
primitive streak to form
MESODERM (middle germ
layer)
• Cells remaining in epiblast
form ECTODERM, completing
formation of 3 germ layers
Ps : primitive streak
Pp : prechodral plate
N : notochord
Op : olfactory placode
Ef : eye field
B : buccal plate
11. • Median strip of mesoderm cells (chordamesoderm)
extending throughout length of embryo induces
NEURAL PLATE formation within overlying ectoderm
• Chordamesoderm also responsible for developing
organizational plan of head
• Mesodermal portion somites myoblasts skeletal
& CT of head
12. • Unique population of cells
develop from ectoderm
along lateral margins of
neural plate – NEURAL
CREST CELLS
• Migrate in the trunk region
form mostly neural,
endocrine & pigment cells
• Migrate in head & neck
also contribute to skeletal
& connective tissues
(cartilage, bone, dentin,
dermis, etc)
13. (In the trunk all skeletal & connective tissues are formed
by mesoderm)
• Of the skeletal or CT of facial region, tooth enamel
(acellular skeletal tissue) is the only one not formed by
crest cells
• Enamel forming cells - derived from ectoderm lining oral
cavity
14. • Pharyngeal region is then
characterized by grooves
(clefts & pouches) in
lateral pharyngeal wall
endoderm & ectoderm
that approach each other,
appear to segment
mesoderm into a number
of bars that become
surrounded by crest
mesenchyme
• Trailing edge of crest cell
mass appears to attach
itself to neural tube at
locations where sensory
ganglia of 5th, 7th, 9th, 10th
cranial nerves will form
15. • Capillary endothelial cells derived from mesoderm cells
invade crest cell mesenchyme from which supporting cells
of developing blood vessels are derived
• Later additional crest cells differentiate into fibroblasts &
smooth muscle cells that will form vessel wall
• Developing blood vessels become interconnected to form
vascular networks
16. • All myoblasts that subsequently
fuse with each other to form
multinucleated striated muscle
fibres derived from -- mesoderm
• Myoblasts that form hypoglossal
muscles derived from ---- somites
located besides developing
hindbrain (Mesodermal portion
somites myoblasts skeletal & CT of
head)
• Myoblasts of extrinsic ocular
muscles originate from --
prechordal plate (pp)
17. • A number of other structures in facial region such as
epithelial components or glands & enamel organ of tooth
bud, are derived from epithelium that grows into
underlying mesenchyme
• CT components (fibroblasts, odontoblasts, cells of tooth
supporting tissues) derived from -- neural crest cells
18. Ectodermal cells
•Nervous system
•Epidermis & its
appendages (hair, nails,
sebaceous -sweat glands)
•Epithelium lining oral
cavity, nasal cavities &
sinuses
•Part of intraoral glands
•Enamel of teeth
Endodermal
cells
•Epithelial lining
of GIT & all
associated
organs
Mesodermal cells
•Muscles & all
structures derived
from connective tissue
(bone, cartilage, blood,
dentin, pulp,
cementum , PDL
19. • On the completion of initial crest cell migration &
vascularization of derived mesenchyme, a series of
outgrowths or swellings termed as facial prominences
initiates next stages of facial development
• Growth & fusion of upper facial prominences produce
primary & secondary palates
20. • After crest cells arrive in future
location of upper face &
midface – frontonasal region
• 1st structures to become evident
: olfactory placode
Thickenings of ectoderm that
appear to be derived atleast
partly from anterior rim of
neural plate
21. • Lateral edges of placodes
actively curl forward, which
enhance initial development of
lateral nasal prominence (LNP)
• High rates of cell proliferation
rapidly brings LNP forward so
that it catches up with medial
nasal prominence (MNP)
• Before that contact has made,
maxillary prominence (MxP)
has already grown forward
from its origin at the proximal
end of 1st visceral arch to merge
with LNP & MNP
22. • All these 3 prominences contribute to initial separation of
developing oral cavity & nasal pit, called as primary palate
• Primary palate forms roof of anterior portion of primitive oral
cavity, as well as forming initial separation between oral and
nasal cavities
• In later development derivatives of primary palate form
portions of upper lip, anterior maxilla & upper incisor teeth
23. • New outgrowths from medial
edges of maxillary prominences
form shelves of secondary palate
• At 9th gestational week, shelves
fuse each other above tongue
• Eventually, most of the hard
palate & all of the soft palate
form from secondary palate
24. • Pituitary gland develops as a
result of inductive interactions
between ventral forebrain & oral
ectoderm , derived in part from
both tissues
• Following initial crest cell
migration, these cells invade area
of developing pituitary gland &
are continuous with cells that will
later form maxillary prominences
• Eventually, crest cells form CT
components of gland
25. • In humans there are total of 6
visceral arches, of which 5th is
rudimentary Pharyngeal or
branchial arches
• Proximal portion of 1st
(mandibular) arch becomes
maxillary prominence
• As heart recedes caudally,
mandibular (1st) & hyoid (2nd)
arches develop further at their
distal portions to become
consolidated in ventral midline
26. • Mesoderm of mandibular (1st) & hyoid arches (2nd) 5th
(trigeminal) & 7th (facial) nerve musculature
• Mesoderm of less well developed 3rd & 4th arches 9th
(glassopharyngeal) & 10th (vagus) nerve musculature
• Myoblasts from 2nd arch, take branches of 7th cranial nerve
& migrate very extensively throughout head & neck to
form contractile components of muscles of facial
expression
27. • Myoblasts from 1st arch contribute mostly to
muscles of mastication, while those from 3rd &
4th arches contribute to pharyngeal & soft palate
musculature
Crest mesenchymal cells -
• skeletal components : temporary visceral arch
cartilages, middle ear cartilages & mandibular
bones
• Connective tissue components : dermis & CT of
tongue
28. • Anterior 2/3rd of tongue is covered by ectoderm, posterior
1/3rd by endoderm
• Thyroid gland forms by invagination of most anterior
endoderm (thyroglossal duct)
• Residual pit (foramen caecum) left in epithelium at site of
invagination marks junction between anterior 2/3rd &
posterior 1/3rd of tongue covered by ectodermal &
endodermal origin resp
• CT components -
• Anterior 2/3rd from 1st arch
• Posterior 1/3rd from 3rd arch
29. • Finally a lateral extension from inner groove
between 1st & 2nd arch gives rise to eustachian
tube which connects pharynx with ear
• External ear or pinna is formed atleast partially
from tissues of 1st & 2nd arches
30. Pattern
• Reflects proportionality
• Physical arrangement of
body at any one time is a
pattern of spatially
proportioned parts
• After 3rd month of fetal
life, proportion of total
body size contributed by
head & face steadily
declines
31. • 3rd month IU development, head - 50%of total body length
• Cranium is large relative to face , >half of total head
• In contrast, limbs are rudimentary & trunk is
underdeveloped
• By birth, trunk & limbs have grown faster than head and
face, so that proportion of the entire body devoted to the
head has decreased to about 30%
• Reflects “Cephalocaudal gradient of growth”
Axis of increased growth extending from head towards feet
32. • Not only within the body, but also within the face, it is
seen
• From that perspective, it is not surprising that mandible,
being farther away from brain tends to grow more &
later than the maxilla, which is closer
33. • Another aspect of normal growth pattern & reason for
gradients of growth is different tissue systems that grow
at different rates are concentrated in various parts of body
Scammon's curves for
growth, 4 major tissue
systems
• Neural tissues : 6 - 7 yrs
• General body tissues (muscle, bone, &
viscera) : S-shaped curve, with a definite
slowing of rate of growth during
childhood & an acceleration at puberty
• Lymphoid tissues : 200% of adult
amount in late childhood, then undergo
involution at the same time that growth
of the genital tissues accelerates rapidly
34. Second important concept in study of growth &
development is variability ( by evaluating a given child
relative to peers on a standard growth chart )
A final major concept in physical growth and
development is timing
• All children undergo a spurt of growth at adolescence,
which can be seen more clearly by plotting change in
height or weight, but growth spurt occurs at different
times in different individuals
35. - Defined as periods of sudden growth acceleration
- Sex-linked
Just before birth
1 year after birth
Infantile spurt – 3 years age
Mixed dentition growth spurt :
Females : 7-9 years, males : 8-11 years
Pre-pubertal growth spurt :
Females : 11-13 years, males : 14-16 years
• Surgical correction should be carried out only after cessation of growth
spurts
36. Measurement Approaches - Acquiring Measurement Data
Craniometry –
• Originally used to study Neanderthal & Cro-Magnon
people whose skulls were found in European caves in 18-
19th centuries
• Based on measurements of skull
37. • Anthropometry –
• Landmarks established in studies of dry skulls are
measured in living individuals simply by using soft tissue
points overlying these bony landmarks
• It is possible to measure length of cranium from a point at
the bridge of nose to a point at the greatest convexity of
rear of skull
Cephalometric Radiology –
• It allows a direct measurement of bony skeletal
dimensions, since bone can be seen through soft tissue
covering in a radiograph
Three-Dimensional Imaging –
• Computed axial tomography, Cone beam CT
38. Experimental Approaches - Vital Staining
• English anatomist John
Hunter in 18th century
• Alizarin (dye) reacts
strongly with Ca at sites
where bone calcification is
occurring
• Gamma-emitting isotope 99mTc can be used to detect areas
of rapid bone growth in humans, but these images are more
useful in diagnosis of localized growth problems than for
studies of growth patterns
39. Implant Radiography (Arne Björk)
• Inert metal pins are placed in bones anywhere in the skeleton,
including face & jaws
• These metal pins are well
tolerated by skeleton, become
permanently incorporated
into bone without causing any
problems & are easily
visualized on a cephalogram
• 6 maxillary & 5 mandibular
tantalum implants ->>>>>>
40. • Homeobox Msx genes - Establishment of body plan, pattern
formation & morphogenesis, expressed differentially in
growth of the mandible
• Msx1 - basal bone
• Msx2 - alveolar process
• Decrease in Hedgehog pathway activity causes
holoprosencephaly (failure of the nose to develop) &
hypotelorism
• Excessive activity causes hypertelorism & frontonasal
dysplasia
• It is estimated that about 2/3rd of 25,000 human genes play a
role in craniofacial development
41. • At the cellular level, there are only 3 possibilities for
growth
1. Increase in the size of individual cells – Hypertrophy
2. Increase in the number of the cells – Hyperplasia
3. Secretion of extracellular material - Contributing to an
increase in size independent of number or size of cells
themselves
42. Growth of soft tissues : Hyperplasia & hypertrophy
Interstitial growth
(characteristic of soft tissues & uncalcified cartilage)
Direct addition of new bone to surface of existing bone can
occur through the activity of cells in periosteum (soft
tissue membrane that covers bone)
Direct or Surface apposition of bone
43. • 3rd month IU - Cartilaginous skeletal development
occurs most rapidly
• A continuous plate of cartilage extends from nasal
capsule posteriorly to foramen magnum at the base of
skull
44. • 4th month IU, ingrowth of blood vascular elements into
various points of chondrocranium -- become centers of
ossification -- cartilage is transformed into bone
Endochondral ossification (mandible)
• Not all bones of the adult skeleton were represented in
embryonic cartilaginous model
• It is possible for bone to form by secretion of bone matrix
directly within connective tissues, without any intermediate
formation of cartilage
Intramembranous ossification
(cranial vault & both jaws)
45. • Development of mandible begins as a condensation of
mesenchyme just lateral to Meckel's cartilage proceeds
entirely by intramembranous bone formation
• Meckel's cartilage disintegrates & largely disappears as the
bony mandible develops
• Remnants -- conductive ossicles of middle ear
• Perichondrium -- sphenomandibular ligament
46. • Condylar cartilage - secondary cartilage, which is
separated by a considerable gap from the body of
mandible
• Early in fetal life, it fuses with developing mandibular
ramus
A) Separate areas of mesenchymal
condensation at 8 weeks
B) Fusion of cartilage with the
mandibular body at 4 months
C) Situation at birth
47. • Maxilla forms from center of mesenchymal condensation
in maxillary process, located on lateral surface of nasal
capsule
• Endochondral ossification does not contribute directly to
formation of maxillary bone
• An accessory cartilage, zygomatic or malar cartilage
totally replaced by bone well before birth, unlike
mandibular condylar cartilage, which persists
48. • Balance of apposition & resorption with new bone being
formed in some areas while old bone is removed in
others, is an essential component of the growth process
• Formation of new bone from a cartilaginous predecessor
or direct bone formation within mesenchyme often is
referred to as modeling
• Changes in shape of this new bone due to resorption &
replacement are referred to as remodeling
49. • Cranial vault (bones that cover upper & outer surface of
brain)
• Cranial base (bony floor under brain, which is dividing
line between cranium face
• Nasomaxillary complex (nose, maxilla & associated small
bones
• Mandible
50. Cranial Vault
• Intramembranous bone formation
• Remodeling & growth occur primarily at periosteum-lined
contact areas between adjacent skull bones i.e. cranial sutures
• At birth, flat bones of skull are widely separated by loose
connective tissues
• These open spaces, fontanelles, allow considerable amount
of deformation of skull at
birth -important in
allowing relatively large
head to pass through
birth canal
51. Cranial Base
• In contrast to cranial vault, bones of cranial base are
formed initially in cartilage -- bone by endochondral
ossification
• Centers of ossification appear early in embryonic life
• As ossification proceeds, bands of cartilage (synchondroses)
remain between centers of ossification
53. Maxilla (Nasomaxillary Complex)
• Postnatally entirely by intramembranous ossification
• Since there is no cartilage replacement, growth occurs
1) Apposition of bone at the sutures that connect maxilla to
cranium & cranial base
2) Surface remodeling
• Growth pattern of face requires that it grows “out from
under the cranium”
1) By a push from behind created by cranial base growth
2) By growth at sutures
54. • Upto about age 6, displacement from cranial base growth is
an important part of maxilla's forward growth
• Failure of cranial base to lengthen normally, as in
achondroplasia & several congenital syndromes midface
deficiency
• At about age 7, cranial base growth stops, then sutural
growth is the only mechanism for bringing maxilla forward
• The overall growth changes are result of both a downward
& forward translation of maxilla & simultaneous surface
remodeling
55. • As the maxilla is carried
downward- forward, its
anterior surface tends to resorb
• Resorption surfaces - dark
yellow
• Only a small area around
anterior nasal spine – exception
• Maxilla is like platform on
wheels, being rolled forward,
while at the same time its
surface (wall in cartoon) is
being reduced on its anterior
side and built up posteriorly,
moving in space opposite to the
direction of overall growth
56. Mandible
• In contrast to maxilla, both endochondral & periosteal activity
are important in growth of mandible
• Displacement created by cranial base growth that moves TMJ
-- negligible role
57. Overall pattern of growth of mandible :
1. If cranium is reference area-- chin moves downward-
forward
2. If data from vital staining experiments -- principal sites of
growth of mandible are the posterior surface of ramus
and condylar & coronoid processes
• There is little change along anterior part of the mandible
(correct)
58. • As a growth site, chin is almost
inactive
• It is translated downward-
forward, as the actual growth
occurs at mandibular condyle &
along the posterior surface of
ramus
• Body of mandible grows longer by
periosteal apposition of bone only
on its posterior surface
• Ramus grows higher by
endochondral replacement at the
condyle accompanied by surface
remodeling
• Conceptually, it is correct to view
mandible as being translated
downward- forward, same time
increasing in size by growing
upward-backward
• Translation occurs largely as the
bone moves downward- forward
along with the soft tissues in
which it is embedded
59. • In infancy, ramus is located at spot where primary first
molar will erupt
• Progressive posterior remodeling creates space for second
primary molar then for sequential eruption of permanent
molar teeth
• However, this growth ceases before enough space has
been created for eruption of third permanent molar,
which becomes impacted in ramus
60. Facial Soft Tissues
Growth of Lips :
• Lips trail behind growth of jaws prior to adolescence, then
undergo a growth spurt to catch up
• Lip height is relatively short -- mixed dentition years
• Lip separation at rest (lip incompetence) is maximal - childhood
Decreases during - adolescence
• Lip thickness reaches its maximum during - adolescence,
decreases—to the point in their 20s and 30s
61. Growth of Nose :
• Growth of nasal bone is complete at age 10
• Nose becomes more prominent at adolescence, especially in
boys
• The lips are framed by the nose above & chin below, both of
which become more prominent with adolescent &
postadolescent growth, while lips do not, so relative
prominence of lips decreases
• This can become an important point in determining how
much lip support should be provided by teeth at the time
orthodontic treatment typically ends in late adolescence
62. Genetic theory (Brodie):
• All growth is controlled by genetic influence & is
preplanned
Sutural theory (Sicher):
• Craniofacial growth occurs at the sutures
• Paired parallel sutures that attach facial areas to skull &
cranial base region push nasomaxillary complex
forwards to pace its growth that of mandible
63. Cartilagenous theory ( James Scott) :
• Intrinsic growth controlling factors are present in cartilage &
periosteum with sutures being only secondary
• Acc to scott, nasal septal cartilage is pacemaker for growth of
entire nasomaxillary complex
• Mandible is considered as diaphysis of long bone, bent into
horseshoe shape with epiphysis removed so that there is
cartilage constituting half an epiphyseal plate at the ends,
which are represented by condyles
64. Functional matrix concept (Melvin Moss) :
• Theorized that growth of face occurs as a response to
functional needs & neurotrophic influences, is mediated by
soft tissue in which jaws are embedded
• In this conceptual view, the soft tissues grow, and both
bone-cartilage react to this form of epigenetic control
• All tissues, organs & functioning spaces taken as a whole
comprise the functional matrix, while skeletal tissues
related to specific tissues related to this specific functional
matrix comprise the skeletal unit
65. • All skeletal tissues originate, grow & function completely
embedded in their several matrices
• Thus, changes in size, shape & spatial position of all
skeletal units including their very maintenance is due to
operational activity of their related functional matrices
66. Multifactorial theory (Von limborgh) :
• 5 factors –
• Intrinsic epigenetic F, genetic control of skeletal units
themselves
• Local epigenetic F : Bone growth determined by genetic
control originating from adjacent structures like brain,
eyes
• General epigenetic F determining growth from distant
structures. Eg. Sex hormones, growth hormone
67. • Local environmental F : non-genetic factors
from local external environment
Eg. Habits, muscle force
• General environmental F, general non-genetic
influences such as nutrition, oxygen
68. Enlow’s expanding V principle
• V shaped pattern of growth, result of differential
deposition & selective resorption of bone
• Bone deposition on inner side
• Bone resorption on outer surface
• Eg. Base of mandible, ends of long bones,
mandibular body, palate, etc
69. Enlow’s counterpart principle
• It states that growth of any given facial or cranial part relates
specifically to other structural & geometric counterparts in
face & cranium
Examples :
• Nasomaxillary complex relates to anterior cranial fossa
• Horizontal dimension of pharyngeal space relates to middle
cranial fossa
• Counterparts : Middle cranial fossa & breadth of ramus,
Maxillary tuberosity & lingual tuberosity
• Mutual counterparts : Maxillary & mandibular arches, Bony
maxilla & corpus of mandible
70. Neurotrophic process in oro-facial growth :
• Neurotrophism is a non-impulse transmitting neural function
that involves axoplasmic transport & provides for long term
interaction between neurons & innervated tissues that
homeostatically regulates morphological, compositional &
functional integrity of those tissues
Types :
• Neuro-epithelial trophism
• Neuro-visceral trophism
• Neuro-muscular trophism
71. Aberrations in embryonic facial development lead to
wide variety of defects. Defects of primary & secondary
palate development are most common
Facial celfts
• Increase in clefting rates associated with children born to
epileptic mothers undergoing phenytoin (dilantin)
therapy & to mothers who smoke cigarettes (due to
hypoxia)
72. Hemifacial microsomia :
• Underdevelopment & abnormalities of TMJ, external &
middle ear, also parotid gland & muscles of mastication
• 3rd most common group of major craniofacial
malformations
• Also found from use of acne drug retinoic acid (accutane)
in pregnant women, also who had taken drug
thalidomide
73. Treacher collin’s syndrome (mandibulofacial
dysostosis):
• Underdevelopment of tissues derived from maxillary,
mandibular, hyoid prominences
• External, middle, inner ear are often defective, clefts of
secondary palate found
• Excessive doses of retinoic acid (accutane)
Labial pits :
• Small pits may persist on either side of midline of lower lip
• Due to failure of embryonic labial pits to disappear
74. Lingual anomalies :
• Median rhomboid glossitis – result of persistance of
tuberculum impar
• Bifid tongue – due to lack of fusion between 2 lateral
lingual prominences
• Thyroid tissue present in the base of tongue
75. Developmental cysts :
• Branchial cleft (cervical) cysts or fistulas- from rests of
epithelium in visceral arch areas
• Thyroglossal duct cysts at or near midline along course of
duct
• Globulomaxillary cysts arise from epithelial rests after
fusion medial, maxillary, lateral nasal prominences
76. • Anterior palatine cysts from remnants of fusion of 2
processes (midline of maxillary alveolar prominence)
• Nasolabial cysts may be originating from epithelial
remnants in cleft lip line
• Malformations in head indicate defective malformation in
heart as spiral septum which divides cornus codis &
truncus arteriosus, is derived from neural crest cells
77. Contemporary orthodontics, Proffit 5th ed
Oral histology & embryology, Orban’s 12th ed
Orthodontics, Bhalajhi 4th ed
Textbook of pediatric dentistry, Nikhil Marwah
3rd ed