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Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
Tooth development  and eruption   /certified fixed orthodontic courses by Indian   dental academy
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Tooth development and eruption /certified fixed orthodontic courses by Indian dental academy

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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.

Indian dental academy provides dental crown &

Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit

www.indiandentalacademy.com ,or call
0091-9248678078

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  • 8 weeks :BUD stage ,10 weeks :CAP stage ,4months BELL stage
  • Trichome stain for dental lamina
  • Transcript

    • 1. GOOD MORNING INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
    • 2. Poet OGDEN NASH must have known the suffering when he penned the words , ”..some tortures are physical and some are mental , But the one that is both is DENTAL…!!! ” www.indiandentalacademy.com
    • 3. EVOLUTION . . . www.indiandentalacademy.com
    • 4. Evolutionary Concept During evolution several significant changes took place in the jaws and teeth. When the reptilian evolve to mammalian , the dentition went from “polyphydont ” (many set of teeth) to “diphydont ” (only two sets of teeth) and then to “homodent ” (all of same teeth) to “heterodent”(different types of teeth like incisors, canines , premolars and molars) . There also arose the necessity for the teeth and bones to develop somewhat synchronously in order that the function of occlusion could be facilitated. www.indiandentalacademy.com
    • 5. Stages of tooth evolution Graphically there are four stages of tooth development:  The reptilian stage (HAPLODONT)  Early mammalian stage (TRICONODONT)  Triangular stage (TRITUBERCULAR MOLAR)  QUADRITUBERCULAR MOLAR www.indiandentalacademy.com
    • 6. …move towards future…the MAN. The REPTILIAN stage There is no occlusion. prehension both jaws single Teeth mainly byconfined to simple or combat and  Dentition includes for Jaw movement simplest form of tooth , the that limits Represented used many teeth in hinge movement. procurement of jaw movement. food. cone. www.indiandentalacademy.com
    • 7. Early mammalian (triconodont) Not seen now except a few breeds of dogs and other carnivores. Exhibits three cusps in line in the posterior teeth. www.indiandentalacademy.com
    • 8. Largest cusp is in middle,with smaller cusp anteriorly and posteriorly.  www.indiandentalacademy.com
    • 9. Occlusion absent tiger Tritubercular (triangular)stage   According to some theories the triconodont line of three changed to a three cornered shape , with the teeth still bypassing each other more or less when the jaw opened or closed. Usually seen in dogs and carnivores. cheetah www.indiandentalacademy.com
    • 10. HELLLO…..frens !!! meet other members of my FAMILY….. Quadritubercular stage During next stage of accommodation to the changes inon It is thethe time as andevelopment created aof humans are the The animals with dentition similar to that projection triangularform and anatomy , the articulationantagonist of the the tooth form that finally occluded with the of the jaws anthropoid apes. opposing accordingly. changed jaw. www.indiandentalacademy.com
    • 11. Hi..myself GIBBON www.indiandentalacademy.com
    • 12. HA…HA…HAAA !!! we are… GORILLAS’ www.indiandentalacademy.com
    • 13. HELLO….myself MONKEY www.indiandentalacademy.com
    • 14. DON’T run..I am ORANGUTAN www.indiandentalacademy.com
    • 15. The shapes of individual teeth in these animals are very close to their counterparts in HUMAN MOUTH. NOTE the TEETH in OCCLUSION SKULL of CHIMPANZEE www.indiandentalacademy.com
    • 16. Characteristics of DENTITION The teeth of the vertebrates are characterized depending upon : MODE OF ATTACHMENT ACRODONT : teeth attached to the jaw by a connective tissue. PLEURODONT THECODONT socket. : teeth are set inside the jaw. : teeth are inserted in the bony www.indiandentalacademy.com
    • 17. Depending on the NUMBER OF SUCCESSIVE SET POLYPHYODONT : teeth replaced throughout life . ex: SHARK TEETH SHARK …so better TAKE CARE www.indiandentalacademy.com
    • 18. Depending on the NUMBER OF SUCCESSIVE SET DIPHYODONT : two sets of teeth. Ex: HUMAN BEING PRIMARY DENTITION Step further towards CIVILIZATION… www.indiandentalacademy.com
    • 19. so care for your TEETH….. and SMILE …..or BETTER choose yourself PERMANENT DENTITION www.indiandentalacademy.com
    • 20. Depending on the NUMBER OF SUCCESSIVE SET MONOPHYODONT : one set of teeth . SHEEP and GOAT Ex. GOAT SHEEP www.indiandentalacademy.com
    • 21. TYPE or SHAPE OF TEETH HOMODONT : a single type of teeth HETRODONT : having various type of teeth . Ex. Human being www.indiandentalacademy.com
    • 22. ORIGIN OF TEETH  THEORY OF CONCRESCENCE   THEORY OF TRITUBERCULY    The mammalian dentition was produced by the fusion of two or more primitive conical teeth and each tubercle with its corresponding root originated as a single tooth. Each of the mammalian teeth was derived from a single reptilian tooth by secondary differentiation of tubercles and roots. This theory is widely ACCEPTED. THEORY OF MULTITUBERCULY  The mammalian dentition is a result of reduction and condensation of primitive tuberculate teeth. www.indiandentalacademy.com
    • 23. Development of TOOTH Dr. Raj Kumar Jaiswal www.indiandentalacademy.com
    • 24. CONTENTS           PRIMARY EPITHELIAL BAND VESTIBULAR LAMINA DENTAL LAMINA BUD STAGE CAP STAGE Enamel Knot Enamel Cord Enamel Niche BELL STAGE Histodifferentiation and Morphodifferentiation Structure of TOOTH GERM DENTAL PAPILLA BREAK UP of Dental Lamina CROWN PATTERN Determination Formation of PERMANENT DENTITION Hard tissue formation / CROWN STAGE ROOT FORMATION FORMATION OF SUPPORTING TISSUE www.indiandentalacademy.com
    • 25.    Development of TOOTH involves many BIOLOGICAL PROCESS including EPITHELIAL MESENCHYMAL relationship Morphogenesis Fibrillogenesis Mineralization www.indiandentalacademy.com
    • 26. WHAT IS ECTOMESENCHYME?  When the histology of primitive Oral cavity is Examined ,it can be seen to be lined by primitive 2-3 layered epithelium covering an Embryonic Connective Tissue which because of its origin from Neural Crest is termed ECTOMESENCHYME. www.indiandentalacademy.com
    • 27. Primary Epithelial Band    After 37th day of development, continuous band of epithelium forms around the mouth from the fusion of separate plates of thickened epithelium. Roughly ‘Horse Shoe’ shaped. Gives rise to Vestibular lamina. Dental lamina. www.indiandentalacademy.com
    • 28. Primary Epithelial Band Vestibular Lamina www.indiandentalacademy.com Dental Lamina
    • 29. Vestibular Lamina   Vestibule forms as a result of proliferation of vestibular lamina into the ectomesenchyme. Its cells rapidly enlarge and then degenerate to form CLEFT which becomes the vestibule between the cheek and tooth bearing area. www.indiandentalacademy.com
    • 30. Dental Lamina  Within the Lamina itself continued and localized proliferative activity leads to formation of series of Epithelial Ingrowths into the Ectomesenchyme at sites corresponding to position of future DECIDUOUS TEETH. From THIS POINT development proceeds in three stages :  BUD stage  CAP stage  BELL stage www.indiandentalacademy.com
    • 31. Bud Stage    First epithelial incursion into the ectomesenchyme of jaw. Simultaneous with the differentiation of each dental lamina round and ovoid swelling arise from basement membrane at ten different point, corresponding to future deciduous teeth. These are primordia of enamel organ ‘the tooth bud’ . www.indiandentalacademy.com
    • 32. BUD STAGE TOOTH BUD and DENTAL LAMINA EIGHT WEEK www.indiandentalacademy.com
    • 33. CAP STAGE ENAMEL ORGAN TENTH WEEK www.indiandentalacademy.com
    • 34. BELL STAGE ENAMEL ORGAN of DECIDUOUS TEETH PRIMORDUM of PERMANENT TOOTH About 4 MONTHS PRIMORDIUM of FIRST PERMANENT MOLAR www.indiandentalacademy.com
    • 35.     Enamel organ (dental organ) Consists of:  Peripherally located low columnar cells.  Centrally located polygonal cells. Functions of Dental organ  Determining shape of crown  Initiating dentin formation  Establishing dentinogingival junction  Forming enamel As a result of increased mitotic activity (of cells of tooth bud and surrounding mesenchyme)and migration of neural crest cell into the area. The ectomesenchymal cells surrounding tooth bud condense. www.indiandentalacademy.com
    • 36. Enamel Organ(dental organ) www.indiandentalacademy.com
    • 37. Condensed Ectomesenchyme  Immediately subjacent to enamel organ known as DENTAL PAPILLA    That surrounds tooth bud and dental papilla known as DENTAL SAC    Tooth pulp Dentin Cementum Periodontal ligament Dental organ,Dental Papilla and Dental follicle constitute TOOTH GERM www.indiandentalacademy.com
    • 38. Tooth Germ www.indiandentalacademy.com
    • 39. Cap stage(proliferation)    Tooth bud continues to proliferate BUT not expand uniformly. Unequal growth in different parts of tooth bud lead to cap stage. Outer enamel epithelium   Peripheral cells covering convexity are CUBOIDAL Inner enamel epithelium  Peripheral cells covering concavity are COLUMNAR www.indiandentalacademy.com
    • 40.  Stellate reticulum (Enamel pulp)    Polygonal cells in center of epithelial enamel organ between inner enamel epithelium and outer enamel epithelium separate as intercellular fluid accumulate. Cells assume branched reticular network. Mucoid fluid rich in albumin.  Gives cushion like consistency may support and protect Enamel forming cells www.indiandentalacademy.com
    • 41. CAP STAGE Oral Epithelium Dental Lamina Tongue Tooth Germ Meckel’s Cartilage Lip www.indiandentalacademy.com
    • 42. ENAMEL CORD DENTAL LAMINA PERMANENT TOOTH BUD ENAMEL CORD or SEPTUM DENTAL PAPILLA www.indiandentalacademy.com
    • 43. ENAMEL NICHE www.indiandentalacademy.com
    • 44. ENAMEL KNOT The cells in the center of the ENAMEL ORGAN are densely packed and form ENAMEL KNOT. ENAMEL CORD A vertical extension of ENAMEL KNOT that arises in Increasing enamel organ. The FUNCTION of both may be to act as a reservoir of dividing cells for growing ENAMEL www.indiandentalacademy.com
    • 45. Bell stage(Histodifferentiation & Morphodifferentiation)  As the invagination of epithelium deepens & the margin continues to grow the enamel organ assumes a bell shape.  Inner Enamel Epithelium  Consists of single layer of cell that differentiate prior to Amelogenesis into tall columnar cells called Ameloblasts. www.indiandentalacademy.com
    • 46.  AMELOBLASTS  Attached to one another by JUNCTIONAL COMPLEX.  Attached to cells of stratum intermedium by DESMOSOME.  These exhert organizing influence on the underlying mesenchymal cells in dental papilla which later differentiate into ODONTOBLASTS.  High glycogen content. www.indiandentalacademy.com
    • 47.  Stratum intermedium     Between the Inner Enamel Epithelium & newly differentiated stellete reticulum the epithelial cells differentiate into a layer of flattened(squamous) cells called stratum intermedium. High degree of metabolic activity. Absent in part of tooth germ that outlines the root portion of tooth but does not form enamel. Along the inner enamel epithelium both layer considered as single functional unit responsible for formation of enamel. www.indiandentalacademy.com
    • 48.  Stellate reticulum    Expand further due to accumulation of intercellular fluid. Before enamel formation begins , stellate reticulum collapses reducing the distance between centrally located ameloblast and nutrient capillaries near outer enamel epithelium. Change begins at the height of the cusp or incisal edge and progress cervically. www.indiandentalacademy.com
    • 49. Stellate Reticulum Accumulation of intercellular fluid www.indiandentalacademy.com Collapsed
    • 50.  Outer enamel epithelium    Cells flatten to low cuboidal form. At the end of bell stage and preparatory to formation of enamel the formerly smooth surface is laid in folds. Between these folds the mesenchyme of dental sac forms papillae and thus provide rich nutritional supply for the intense metabolic activity of avascular enamel organ. www.indiandentalacademy.com
    • 51.  Dental lamina  In all teeth except permanent molars the dental lamina proliferates at its deep end to give rise to enamel organ of permanent teeth. Distal extension www.indiandentalacademy.com
    • 52.  Dental papilla     Enclosed in invaginated portion of enamel organ. Before inner enamel epithelium produce enamel the peripheral cells of mesenchymal dental papilla differentiate into odontoblasts under organizing influence of epithelium. First assume cuboidal form and later columnar and acquire specific potential to produce dentin. ‘Membrana preformativa’ – basement membrane that separates the enamel organ and dental papilla just prior to dentin formation. www.indiandentalacademy.com
    • 53.  Dental sac   Before formation of dental tissue begins, dental sac shows circular arrangement of its fibers and resembles capsular structure. With development of root, fibers of dental sac differentiate into periodontal ligament fibers that become embedded in developing cementum and alveolar bone. www.indiandentalacademy.com
    • 54. BELL STAGE Gland of Serres Oral Epithelium Dental Lamina Stellate Reticulum Bud for Permanent Tooth External Enamel Epithelium Dental Papilla Inner Enamel Epithelium www.indiandentalacademy.com
    • 55. INITIAL A B D DP DF E EO O N HS BELL STAGES STAGE ADVANCE STAGES AMELOBLAST BONE DENTINE - DENTAL PAPILLA - DENTAL FOLLICLE ENAMEL - ENAMEL ORGAN ODONTOBLAST NECK OF TOOTH – HERTWIG ROOT SHEATH www.indiandentalacademy.com
    • 56. Advanced Bell Stage  The boundary between the inner enamel epithelium and odontoblasts outlines future dentino-enamel junction and cervical portion of enamel organ give rise to epithelial root sheath of Hertwig. www.indiandentalacademy.com
    • 57. ADVANCED BELL STAGE Oral Epithelium Inner Enamel Epithelium Enamel and Dentin formation starting at Cusp tip Dental Papilla Cervical Loop Alveolar Bone Nerve Bundle www.indiandentalacademy.com
    • 58. …magnified view showing HARD TISSUE FORMATION AMELOBLASTS ENAMEL STRATUM INTERMEDIUM STELLATE RETICULUM PRE DENTIN DENTIN ODONTOBLASTS PULP www.indiandentalacademy.com
    • 59. COLUMNAR AMELOBLASTS ENAMEL MATRIX MINERALIZING DENTINE PREDENTINE ODONTOBLASTS FIBROBLASTS OF PULP HERTWIG’s ROOT SHEATH VERTICAL SECTION through NECK of TOOTH www.indiandentalacademy.com
    • 60. Hertwig’s Epithelial Root Sheath and Root Formation Root development begins after enamel and dentin formation has reached future cementoenamel junction. HERS is formed from enamel organ.  Molds the shape of root  Initiates dentin formation.  Consists of outer and inner enamel epithelium only. www.indiandentalacademy.com
    • 61. EPITHELIAL DIAPHRAGM AND PROLIFERATION ZONE OF PUL www.indiandentalacademy.com
    • 62. ELONGATION of HERS CORONAL to EPITHELIAL DIAPHRAGM ROOT SHEATH BROKEN www.indiandentalacademy.com
    • 63.  Prior to beginning of root formation , root sheath forms EPITHELIAL DIAPHRAGM     The outer and inner enamel epithelium bend at future CEJ into a horizontal plane narrowing the wide cervical opening of the tooth germ. The proliferation of cells of epithelial diaphragm is accompanied by proliferation of cells of connective tissue of pulp which occurs in area adjacent to the diaphragm. The free end of the diaphragm does not grow into connective tissue but the epithelium proliferates coronal to the epithelial diaphragm. The differentiation of Odontoblast & formation of Dentin follow the lengthening of root sheath. www.indiandentalacademy.com
    • 64. ROOT FORMATION INITIAL STAGES CERVICAL LOOP MIDWAY FINAL STAGE APICAL FORAMEN www.indiandentalacademy.com
    • 65. At the same time the connective tissue of Dental sac surrounding the root sheath proliferates and invades continuous Double epithelial layer dividing it into network of epithelial strands.  Epithelium is moved away from the surface of dentin so that the connective tissue cells come into contact with the outer surface of the dentin and differentiate into cementoblast that deposit a layer of cementum onto the surface of dentin.  In last stages of root development the proliferation of the epithelium in the diaphragm lags behind that of the pulpal connective tissue. Wide apical foramen is reduced first to width of diaphragmatic opening itself and later is further narrowed by apposition of dentin and cementum to the apex of the root. www.indiandentalacademy.com
    • 66.  In multi-rooted teeth:       Differential growth of epithelial diaphragm causes division of the root trunk in 2/3 roots. During the general growth of enamel organ the expansion of its cervical opening occurs in such a way that long tongue-like extension of horizontal diaphragm develops. Two extension in lower molars and three in upper. Before division of the root trunk occurs the free end of these horizontal epithelial flaps grow towards each other and fuse. The single coronal opening of the coronal enamel organ is than divided into two-three openings. On the pulpal surface of dividing epithelial bridges dentin formation starts and on the periphery of each opening root development follows in the same way as for singlewww.indiandentalacademy.com rooted teeth.
    • 67. During of growth of TOOTH GERM… EPITHELIAL DIAPHRAGM HORIZONTAL EPITHELIAL FLAPS PROLIFERAT and UNITE EXPAND ECCENTRICALLY E www.indiandentalacademy.com
    • 68. FORMATION IN PROGRESS as a result BEGINNING OF ROOT ELONGATION OCCURS DENTIN FORMATION AT BIFURCATION MESIAL DISTAL DEVELOPMENT OF TWO ROOTED TOOTH www.indiandentalacademy.com
    • 69. Initiation Specific cell of dental lamina have potential to form enamel (dental) organ. Different teeth at different time/definite time. Initiation induction requires ECTOMESENCHYMAL-EPITHELIAL interaction. www.indiandentalacademy.com
    • 70. LACK of INITIATION results in: ABSENCE of either SINGLE TOOTH or MULTIPLE TEETH LEADING TO CROSS BITE DECIDUOUS DENTITION PERMANENT DENTITION FLATTENING of ARCH MISSING LATERAL INCISORS PARTIAL ANODONTIA www.indiandentalacademy.com
    • 71. SUBMERGING LOWER 2 nd MOLAR Due to CONGENITAL ABSENCE PERMANENT 2 nd PREMOLARS www.indiandentalacademy.com
    • 72. OLIGODONTIA IMPEDES THE DEVELOPMENT OF ARCH Missing teeth www.indiandentalacademy.com
    • 73. ABNORMAL INITIATION results in : Development of SINGLE or MULTIPLE SUPERNUMERARY teeth CLIEDOCRANIAL DYSPLASIA MESIODENS www.indiandentalacademy.com
    • 74. Proliferation Enhanced proliferative activity ensues at point of initiation and results in the BUD,CAP, and BELL stages of development. Proliferative growth causes regular changes in the size and proportions of the growing tooth germ. www.indiandentalacademy.com
    • 75. Histodifferentiation The cells become restricted in their functions. They differentiate and give up their capacity to multiply as they assume their new function ; this law governs all differentiating cells. This phase reaches its highest development in the BELL stage , just preceding the beginning of formation and apposition of DENTIN and ENAMEL. www.indiandentalacademy.com
    • 76. DISTURBANCES during this stage may lead to… AMELOGENESIS IMPERFECTA : Hypoplastic type AMELOGENESIS IMPERFECTA : Hypomineralized type DENTOGENESIS IMPERFECTA AMELOGENESIS IMPERFECTA :Hypomature type SHORT Amber coloured tooth MARKED Attrition www.indiandentalacademy.com
    • 77. Morphodifferentiation The morphologic pattern,or basic form and relative size of the future tooth,is established by morphodifferentiation,that is,by DIFFERENTIAL GROWTH. Morphodifferentiation therefore is IMPOSSIBLE without proliferation. The ADVANCED BELL stage marks not only active histodiferentiation but also an important stage of morphodifferentiation in the crown,outlining the future DENTINOENAMEL JUNCTION. The DENTINOENAMEL and CEMENTOENAMEL junctions which are different and characteristic for each type of tooth,act as BLUE-PRINT pattern. www.indiandentalacademy.com
    • 78. Disturbances may effect the FORM and SIZE of the tooth WITHOUT impairing the function of ameloblasts and odontoblasts. MICRODONTIA MACRODONTIA of entire dentition in relation to basal bone MICRODONTIA Oversized LATERAL INCISORS MACRODONTIA of UPPER teeth in relation to basal bone PEG shaped LATERAL CONCRESCENCE: FUSION :union of the dentin GEMINATION :incomplete union of cellular TWINNING:complete division of two teeth,from two tooth division of of twotooth bud Cementum bud of one toothsingleto teeth,from buds. create two teeth two buds. www.indiandentalacademy.com
    • 79. Apposition Apposition is the deposition of the MATRIX of the hard dental structures. Appositional growth of enamel and dentin is characterized by regular and rhythmic deposition of an extracellular matrix. It is the fulfillment of the plans outlined at the stages of Histodifferentiation and Morphodifferentiation. Both HYPOPLASIA and HYPOCALCIFICATION can occur as a result of an insult to this phase. www.indiandentalacademy.com
    • 80. Factors affecting DEVELOPMENT  Systemic factors  ACCELERATING EFFECT :on the whole very rare but reported to be due to  Hyper thyroidism  Hyper pitutarism  Turner’s syndrome www.indiandentalacademy.com
    • 81.  RETARDING AFFECT : more common in permanent dentition due to  Hypo thyroidism  Hypo pitutarism  Cleidocranial dysostosis  Down’s syndrome  Achondroplasia  Hypovitaminoses ( A and D)  Osteopetrosis www.indiandentalacademy.com
    • 82. Eruption of Tooth and Theories of eruption Dr. Raj Kumar Jaiswal www.indiandentalacademy.com
    • 83. Eruption   Latin – ‘erumpere’ – to break out. Properly refers/understood to mean the axial or occlusal movement of the tooth from its developmental position within the jaw to its functional position in the occlusal position. www.indiandentalacademy.com
    • 84. Theories of Eruption Tooth eruption is an essential process for the survival of many different species and although the movement of teeth into function has been the subject of extensive research there is no consensus as to the mechanisms involved Mechanism that brings about tooth movement is still debatable and is likely to be a combination of number of factors. www.indiandentalacademy.com
    • 85. Most talked about theories are:  Root formation(elongation)theory  Bone remodeling theory  Vascular pressure theory  Periodontal ligament traction theory  Pulp theory  Genetic input theory www.indiandentalacademy.com
    • 86. Root formation theory In 1978 HUNTER attributed to mechanism of root elongation  Root formation follows crown formation and involves cellular proliferation of new tissue that must be accommodated by either movement of the crown of tooth or resorption of bone at the base of its socket. It is the former that actually happens , but if occlusal movement is prevented resorption of bone at the base of socket occurs. If root formation is to result in an eruptive force the apical growth of root needs to be translated into occlusal movement and requires the presence of a fixed base. www.indiandentalacademy.com
    • 87. BUT…. www.indiandentalacademy.com
    • 88. Bone at the base of socket cannot act as a fixed base because pressure on bone results in its resorption. Some teeth move a distance greater than the length of their roots. Eruption movement can occur after completion of root formation. Experimental resection preventing further root formation does not stop eruptive tooth movement. All indicating root formation CANNOT be responsible for eruptive tooth movement. www.indiandentalacademy.com
    • 89. STOPPED BONE TOOTH GERM BONE OCCLUSAL MOVEMENT OF CROWN www.indiandentalacademy.com BONE RESORPTION
    • 90. Advocates of root formation theory like a postulated existence of “Cushion Hammock Ligament”straddling the base of the socket from one bony wall to the other sling. Its function was to provide fixed base for growing root to react against… BUT …the structure described as cushion hammock ligament is Pulp delineating membrane that runs across apex of the tooth and has no bony insertion,it CANNOT act as FIXED BASE. www.indiandentalacademy.com
    • 91. Bone remodeling theory Is important to permit tooth movement. In animals that exhibit genetic deficiency of OSTEOBLAST ,tooth eruption is prevented . If tooth germ is removed experimentally and dental follicle left intact an eruptive pathway is forms in overlying bone. Marks and Cahill have confirmed that tooth has no active role in the process , since metal or silicone replicas of calcified crowns , placed within follicle ,also erupts. www.indiandentalacademy.com
    • 92. These experiment establish ABSOLUTE requirement for DENTAL FOLLICLE to achieve: Bony remodelling and tooth eruption. Provides the source for new bone forming cells and conduit for osteoclast derived from Monocyte through its vascular supply. RECENT STUDIES show that resorptive process may be regulated by local growth factors such as Transforming growth factor Beta-1(TGF-ß1)and Epidermal growth factor (EGF) produced within or around Dental follicle. www.indiandentalacademy.com
    • 93. These growth factors seem to Chemoattaract monocytes from the peripheral bood vessels around the dental follicle. Resorptive process begins with the formation of osteoclasts from coalescence of the monocyte. www.indiandentalacademy.com
    • 94. Factors influencing tooth to erupt Intraosseously:  Density of bone.  Rate of bone resorption.  The overlying tissue Bone  Primary tooth root  Gingiva Must resorb to provide an eruptive path.  Force must be generated to move the tooth vertically. Resorption over tooth seems to be dependent only on the presence of coronal portion of the dental follicle .  www.indiandentalacademy.com
    • 95. Vascular pressure theory CONSTANT suggested that blood pressure provided the eruptive force but there has been evidence for and against the theory. FOR:  Teeth develop in a vascular site and direct relationship between conglomerates of beneath the developing crown and number of cusps and roots.  Periodontal ligament has a rich vascular supply.  Oscillatory movement of erupted teeth occurs in synchrony with the pulse.  Vasculature is under physiological control throughout life. www.indiandentalacademy.com
    • 96. Could the VASCULATURE be source of ERUPTIVE FORCE…??? www.indiandentalacademy.com
    • 97. There is close relationship between Osmotic tissue fluid pressure and Blood pressure.  NESS and SMALE suggested that the pressures derived from the vasculature would be exerted by the tissue fluid.  While tissue fluid osmolarity can reasonably be anticipated to change Apical pressure… Hypotensive rats show no changes in unimpeded eruption rates. www.indiandentalacademy.com
    • 98.   The Pulsatile nature of blood flow within the follicle and periodontal ligament and its significance for tooth eruption has been noted. Cyclic intermittent forces –impulses have been shown to enhance cellular activity during bone remodelling and gene expression within the endothelium therefore their affects on bone and the tooth. www.indiandentalacademy.com
    • 99. Tooth develop,erupt and function in a vascular site constantly exposed to PULSATIVE forces arising from blood flow. Repetative impulses acting on the calcified crown similar to the action of a hammer on a nail,are the likely the eruptive force. www.indiandentalacademy.com
    • 100. BUT….. Even the resection of root and thus the vasculature CANNOT prevent the eruption of tooth. www.indiandentalacademy.com
    • 101. Periodontal ligament traction theory The eruptive movement could be brought about a combination of events envolving a force initiated by the periodontal ligament fibroblasts. This force is transmitted to the extracellular compartment via FIBRONEXUS and to collagen fibre bundle which align in an appropiate inclination brought about by root formation bring about tooth movement. These fibre bundles have the ability to remodel for eruption to continue and interferance with this ability effects the process. www.indiandentalacademy.com
    • 102. The removal of bone to create eruptive pathway is also dictated by the tissues surrounding the tooth. Evidence to support this view:  Experiments delineating the role of follicle (from which periodontal ligament forms)  Experiments on continuously erupting Rodent incisor designed to eliminate the effects of root growth and vascular supply show that as long as periodontal ligament tissue is available tooth movement occurs. www.indiandentalacademy.com
    • 103.   Drugs that interrupt proper collagen formation in ligament also interfere with eruption. Tissue culture experiment have shown that ligament fibroblast are able to contract a collagen gel which in turn brings about movement of disk of root tissue attached to that gel. www.indiandentalacademy.com
    • 104. PERIODONTAL LIGAMENT Before CONTRACTION ORAL MUCOSA After CONTRACTION BONE www.indiandentalacademy.com
    • 105. Pulp theory This theory suggests that a propulsive force is generated by extrusion of pulp through THREE mechanisms.    Growth of DENTINE Interstitial PULP growth Hydraulic effects within VASCULATURE www.indiandentalacademy.com
    • 106. Here in first stage , There is growth of dentine. This causes interstitial growth of the pulp tissue VASCULAR SYSTEM DEVELOPS Hydraulic effects within the vasculature causes eruption of teeth www.indiandentalacademy.com
    • 107. BUT…… HERZBERG and SCHOUR removed the PULP of RODENTS incisors and found that its eruption rates were UNAFFECTED. www.indiandentalacademy.com
    • 108. Genetic input theory If tooth eruption is to be explained at the cellular and molecular level ,a degree of genetic control is highly likely. In normal development of the occlusion,incisors develop before premolars and this process of eruption is disturbed in a number of Genetic Disorders. www.indiandentalacademy.com
    • 109. A classification of these relationships has been represented by SANK.  Inherited defects : amelogenesis imperfecta  Disorders with supernumerary teeth or crowding of teeth  Growth retardation syndromes  Miscellaneous disorders    Hypophostasia Juvenile periodontitis Papillion lefevre syndrome www.indiandentalacademy.com
    • 110. Although variety of theories have attempted to identify the eruptive force , none been fully supported by experimental evidence. Specific changes in the cellular activity of bone surrounding the erupting tooth provide indirect information about the mechanics of the process that need to be accounted for in ANY theory of eruption. www.indiandentalacademy.com
    • 111. Mechanics of eruption When a tooth starts to erupt there is change in its momentum , therefore a force MUST be present.  The spherical bony crypt prior to calcification of crown exists because forces are present in the follicle that resists bone apposition. Eventhough the magnitude and direction of the individual forces cannot be determined,a summation of their distribution can be represented as series of RADIAL force vector extending to the surface of a sphere. www.indiandentalacademy.com
    • 112. Calcification the crown provides a new mass against which the force within the follicle can act. Although the action force is such that the tooth will move occulusally , the bone resorption initially occurs in the opposite direction along the axis of force.  Bone remodeling around the erupting tooth results from the action of many forces within the follicle.In order for a tooth to move the action of eruptive force must be greater than the sum of forces resisting its movement.  As the tooth erupts the dynamic relationships between the surrounding alveolar bone , the eruptive force and the erupting tooth influence the rate of eruption.  www.indiandentalacademy.com
    • 113. In order for a tooth to the tooth erupts the dynamic relationships between move the action of the surrounding alveolar bone , eruptive force must be greater than the sum of the eruptive force and the forces resisting its erupting tooth influence the Calcification of the movement. RATE OF ERUPTION. crown provides a NEW MASS against which the force within the follicle can SERIES OF RADIAL FORCE act. VECTOR EXTENDING TO THE SURFACE OF A SPHERE. As www.indiandentalacademy.com
    • 114. On emergence the resistance is greatly reduced resulting in accelerated rate of eruption until a new equilibrium of forces is established. However eruption is only part of total pattern of physiologic tooth movement , because teeth also undergoes complex movement related to maintaining their position in the growing jaws and compensating for masticatory wear. www.indiandentalacademy.com
    • 115. Shedding of deciduous teeth The physiologic process resulting in elimination of the deciduous dentition is called SHEDDING or EXFOLIATION. www.indiandentalacademy.com
    • 116. Physiologic tooth movement Is described as :  Pre-eruptive tooth movement  Eruptive tooth movement  Post eruptive tooth movement www.indiandentalacademy.com
    • 117. Pre-eruptive tooth movement When deciduous tooth germ first differentiate they are extremely small and there is a good deal of space for them in the developing jaw. Because the tooth germs grow rapidly, however they become crowded together particularly in the anterior of jaw. www.indiandentalacademy.com
    • 118.  This crowding is gradually alleviated by the lengthening of the jaws , which permits the 2nd deciduous molar tooth germ to move backwards and anterior tooth germ move forward.  At the same time the tooth germs are also moving bodily outward and upward , or downward as the case may be , as the jaws increases in length as well as in width and height.  Successional tooth germs develop on the lingual aspect of their deciduous predecessor in the same bony crypt. From this position the tooth germ shift considerably as the jaw develop. www.indiandentalacademy.com
    • 119. INCISOR and CANINE  Eventually come to occupy a position in their own bony crypt on lingual surface of their deciduous. PREMOLARS  Also in their own bony crypt finally position between the divergent roots of the deciduous molars. www.indiandentalacademy.com
    • 120. ERUPTING INCISOR DECIDUOUS INCISOR BONE BETWEEN DECIDUOUS TOOTH AND SUCCESSOR ENAMEL OF PERMANENT INCISOR DENTIN www.indiandentalacademy.com
    • 121. ERUPTING INCISOR ENAMEL DISSOLVED AWAY DENTIN GINGIVA PULP FOLLICLE ENAMEL SPACE REDUCED ENAMEL EPITHELIUM ALVEOLAR BONE ROOT OF DECIDUOUS TOOTH AREA OF RESORPTION PERMANENT TOOTH www.indiandentalacademy.com
    • 122. ERUPTING CANINE DECIDUOUS CANINE RESORPTION RESORPTION OF ROOT RERSORPTION OF BONE PERMANENT CANINE www.indiandentalacademy.com
    • 123. ERUPTING PREMOLAR DECIDUOUS FIRST MOLAR ROOT RESORPTION PERMANENT TOOTH GERM www.indiandentalacademy.com
    • 124. PERMANENT MOLAR tooth germ  No predecessors , develop from backward extension of the dental lamina as there is little space to accommodate these tooth germ.  In MAXILLA : MOLAR tooth germ first develop with their occlusal surface facing DISTALLY,and can swing into position when maxilla has grown sufficiently.  In MANDIBLE : permanent MOLAR develop with their axis showing MESIAL inclination , vertical later. www.indiandentalacademy.com
    • 125. OCCLUSAL surface facing DISTALLY,and can swing into position MAXILLA www.indiandentalacademy.com
    • 126. PERMANENT MOLAR develop with their axis showing MESIAL inclination , VERTICAL later. MANDIBLE www.indiandentalacademy.com
    • 127. ERUPTION OF MOLAR At 6 to 7 years At 4 years 6 months Perm.FIRST MOLAR at 3 years www.indiandentalacademy.com
    • 128. EXFOLIATED DECIDUOUS CANINE DECIDUOUS MOLAR www.indiandentalacademy.com
    • 129. Pre eruptive movements of both deciduous and permanent tooth germs are best thought of as the movement required to place the teeth within the jaw in a position for eruptive tooth movement. Pre eruptive tooth movements are combination of two factors:  Total bodily movement of the tooth germ  Growth , in which one part of the tooth germ remains fixed while rest continues to grow , leading to change in the center of tooth germ. Ex: deciduous incisor maintain their position relative to oral mucosa as jaw increase in height. www.indiandentalacademy.com
    • 130. Histology As pre eruptive tooth movements occurs in a intraosseous location , such movement is reflected in the patterns of bone remodeling within the crypt wall. Ex: bodily MESIAL movement –bone resorption occurs on mesial surface of crypt (OSTEOCLASTIC activity) and bone deposition on distal surface / wall as a “Filling in process” Whether bony remodeling to position bony crypt is important as a mechanism or whether its merely an adaptive e response is DEBATABLE. www.indiandentalacademy.com
    • 131. Eruptive tooth movement During this phase the tooth movement from its position within the bone of the jaw to the functional position in occlusion and the principal direction of the movement is occlusal or axial. www.indiandentalacademy.com
    • 132. HISTOLOGY Significant developmental event associated with the eruptive tooth movement are:  Formation of roots  Periodontal ligament  Dentogingival junction The periodontal ligament develops only after root formation has been initiated and once established it must be remodeled to permit continued tooth movement. www.indiandentalacademy.com
    • 133. The architecture of tissue in advance of erupting successional teeth from that found in advance of deciduous teeth. The fibrocellular follicle surrounding a successional tooth retains its connection with the lamina propria of oral mucous membrane by means of a strand of fibrous tissue containing remnants of the dental lamina known as GUBERNACULAR CORD. www.indiandentalacademy.com
    • 134. GUBERNACULAR CORD www.indiandentalacademy.com
    • 135. “in dried skull holes can be identified in jaw on the lingual surface of the deciduous teeth” These holes which once contained the gubernacular cord is known as GUBERNACULAR CANAL. As the successional tooth erupts its gubernacular canal is rapidly widened by local osteoclastic activity , delineating the eruptive pathway for the tooth. www.indiandentalacademy.com
    • 136. GUBERNACULAR CANALS www.indiandentalacademy.com
    • 137.  Once erupting tooth appears in the oral cavity its subjected to environmental factor that help to determine its position in dental arch.  Factors:Muscle forces -tongue -cheek -lips  Forces of contact of erupting teeth with other erupting tooth or with other erupted tooth.  Once erupted it continues to erupt at the same rate of 1mm every 3 month, only slowing as it meets its antagonist in opposing arch. www.indiandentalacademy.com
    • 138. Post eruptive tooth movement These are those movements made by the tooth after it has reached its functional position in the occlusal plane. Divided into 3 categories:  Movements made to accommodate growing jaws  Compensation for occlusal wear  Accommodation for interproximal wear www.indiandentalacademy.com
    • 139. Movement made to accommodate the Growing Jaws  These are completed toward the end of 2nd decade when jaw growth ceases.  Recent studies have shown that readjustment occurs between 14 and 18 years. www.indiandentalacademy.com
    • 140.    Seen histologically as readjustment of the position of the tooth socket achieved by formation of new bone at alveolar crest and on the socket floor to keep pace with height of jaws. Apices of teeth move away 2-3mm away from inferior dental canal (regarded as fixed reference point) Seen relatively earlier in girls than boys and is related to burst of condylar growth that separates jaws and teeth , permitting further eruptive movement . www.indiandentalacademy.com
    • 141. Compensation for OCCLUSAL wear   Is often stated that it is achieved by continued cementum deposition around apex of the tooth , but deposition of cementum occurs only after tooth has moved . No evidence as such is present that forces causing tooth eruption are still available to bring about sufficient axial movement to compensate axial wear. www.indiandentalacademy.com
    • 142. OCCLUSAL PLANE DEPOSITION of CEMENTUM ALVEOLAR BONE ATTRITION COMPENSATION OF OCCLUSAL WEAR www.indiandentalacademy.com
    • 143. Accommodation for INTERPROXIMAL wear Wear also occurs at the contact points between teeth and their proximal surfaces. This interproximal wear is compensated by process known as MESIAL or APPROXIMAL DRIFT. Factors which bring about drift:  Anterior component of occlusal force  Contraction of transseptal ligament  Soft tissue pressure www.indiandentalacademy.com
    • 144. APPOSITION RESORPTION MESIAL DRIFT www.indiandentalacademy.com
    • 145. Anterior component of force : When teeth are brought in contact ,ex:when jaws are clenched , a forwardly force is generated . This force is a result of  Mesial inclination of most teeth.  Summation of intercuspal plane producing a forwardly directed force. In case of incisor which are inclined labially , it is expected that they move in same direction BUT infact they move MESIALLY explained by “BILLIARD BALL ANALOGY” www.indiandentalacademy.com
    • 146. Billiard ball analogy “…if the two touching balls are in line with the pocket , no matter how the first ball is struck second enters the pocket as it travels at right angle to the common tangent between the two balls…” Following this example the CANINES and INCISORS move in direction at right angles to the common tangent drawn through contact points. This leads to IMBRICATION often found in older dentition. www.indiandentalacademy.com
    • 147. BILLIARD BALL ANALOGY www.indiandentalacademy.com
    • 148. Cuspal inclination is a significant factor which can be demonstrated by selectively grinding cusp in such a way as to either enhance or even reverse the direction of occlusal force.  When opposing teeth are removed , thereby eliminating the biting force the mesial migration of teeth is slowed BUT not halted indicating the presence of some other force. Here the TRANSSEPTAL fibres of periodontal ligament have been implicated.  www.indiandentalacademy.com
    • 149. Contraction of Transseptal ligament The periodontal ligament are important in maintaining tooth position. It is suggested that transseptal fibre running between adjacent teeth across the alveolar process draw neighbouring teeth together and maintain them in contact . Evidence to support this:  Relapse of orthodontically moved teeth is much reduced if gingivectomy removing transseptal ligament is performed.  Demonstrated experimentally that in bisected tooth the two halves separates from each other , if however the transseptal ligament are previously cut this separation does not occur. www.indiandentalacademy.com
    • 150. OCCLUSAL PLANE TRANSSEPTAL FIBRES ACTION of FIBRES TRANSSEPTAL www.indiandentalacademy.com
    • 151.  The approximal contacts are disked , teeth move to reestablish contact ,however if the teeth is also ground out of occlusion and approximate surfaces disked the rate of drift is slowed. So until the contrary is demonstrated it must be assumed that the Mesial Drift is achieved by contractile mechanism associated with transseptal ligament fibres and enhanced by occlusal forces. www.indiandentalacademy.com
    • 152. Soft tissue pressure The pressure generated by cheeks and tongue may push teeth mesially. However if such pressure from soft tissue is eliminated by constructing acrylic dome over teeth mesial drift still occurs. Suggesting soft tissue pressure does not have a major role , however it does influence tooth position even if it does NOT cause tooth movement. www.indiandentalacademy.com
    • 153. TYPES OF ERUPTION Three distinct type of teeth are differentiated by their eruption pattern :  CONTINUOUSLY GROWING  Tooth formation and eruption occurs throughout the life. RODENT  Dental tissue are formed from a proliferative base.  Anatomic crown and root very similar morphologically.  Teeth have extensive wear.  Eruption velocity relatively rapid , increases whenever the velocity of wear increases or antagonist tooth is removed.  Ex. Incisor of rodents and lyomorphs. www.indiandentalacademy.com
    • 154. CONTINUOUSLY EXTRUDING Teeth stop forming once root formation is SHEEP CATTLE complete.  Well defined crown and root.  Moderate occlusal wear.  Height of clinical crown is maintained by eruption and apical migration of epithelial attachment without simultaneous deposition of alveolar bone.  As occlusal wear progress tooth eventually loosens and exfoliates completely.  Ex. Cheek teeth of cattle and sheep.  www.indiandentalacademy.com
    • 155. CONTINUOUSLY INVESTED TEETH Human teeth belong to this type of eruption.  Teeth stop forming after predictable amount of root development has occurred.  Distinct anatomic crown and root structure.  Alveolar bone remodels in response to eruption.  The clinical crown shortens(in absence of periodontal disease) as the tooth erupts to maintain vertical height and occlusal function and brings about alveolar bone with it.  www.indiandentalacademy.com
    • 156. ERUPTION RHYTHM The circadian rhythm in eruption is potentially significant in clinical practice.  The teeth intrude transiently in conjunction with masticatory activity and then erupts significantly overnight. The mean daily eruption velocity was seen to be 71um/day. www.indiandentalacademy.com
    • 157. CLINICAL SIGNIFICANCE  Timing of eruption  Controlling intervention  Excessive eruption of posterior teeth is a major cause of the long face , and control of eruption during growth seems to be key to successful treatment.  The amount of force , its direction and the total hours of wear of appliance are often considered the most important factor that affect treatment outcome. www.indiandentalacademy.com
    • 158.  Teeth erupt primarily during night with little or no net eruption during the day , it is quite possible that wearing the appliance is affective during the night and early morning period when the eruption is most active. www.indiandentalacademy.com
    • 159.  Daily rhythm in skeletal growth  Skeletal growth requires an adequate levels of HGH which increases in the night.  The rhythm in tooth eruption also reflects this soon after the child goes to sleep.  The clinician should be aware that there is a rhythm in skeletal growth and modification of treatment may be therefore be more effective during night than during the day. www.indiandentalacademy.com
    • 160. TEETHING Teething is a term limited by common usage to eruption of primary dentition which ususally begins in fifth or sixth month of a child’s life. In most cases eruption of teeth causes no distress to the child but sometimes causes local irritation , which is usually minor but may be fewer enough to disturb child’s sleep. www.indiandentalacademy.com
    • 161. Clinical features of TEETHING  LOCAL SIGNS  Hypermia or swelling of the mucosa overlying the erupting teeth.  Patches of erythema on the cheeks.  Flushing may also occur in the skin of adjacent cheek. www.indiandentalacademy.com
    • 162. TEETHING www.indiandentalacademy.com
    • 163.  SYSTEMIC SIGNS        General irritability and crying. loss of appetite. Sleeplessness , restlessness Increased salivation and drooling Increased thirst Circumoral rash Cough www.indiandentalacademy.com
    • 164. Associated problems  SYSTEMIC    Fever Diarrhea Vomiting LOCAL Eruption hematoma Eruption sequestrum Ectopic eruption Transposition www.indiandentalacademy.com
    • 165. REMNANTS OF ROOTS OF FIRST MOLAR www.indiandentalacademy.com
    • 166. PERMANENT CANINE Causing resorption of DECIDUOUS LATERAL INCISO and CANINE MISSING PERMANENT LATERL INCISOR www.indiandentalacademy.com
    • 167. IMPACTED CANINE www.indiandentalacademy.com
    • 168. Deciduous INCISORS Perm. CANINE TRANSPOSITION www.indiandentalacademy.com
    • 169. LOCAL FACTORS             Aberrant tooth position Lack of space in arch Very early loss of predecessor Ectopic eruption Congenital absence of teeth Ankylosis of predecessor Retained tooth or persisting deciduous root remnants Arrested tooth formation (trauma) Supernumerary tooth Tumor Cyst Abnormal habit exerting muscular forces www.indiandentalacademy.com
    • 170. …lastly the books  ORAL HISTOLOGY      Tencate Orban Dental Anatomy,Physiology and Occlusion -Wheeler’s Text book of PEDODONTICS -Shoba Tandon Kardos TB:The mechanics of tooth eruption,Br Dent J 181:91,1996 www.indiandentalacademy.com
    • 171. THANK YOU… www.indiandentalacademy.com

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