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Tooth eruption

Introduction.
History
Stages of tooth eruption.
Histology of tooth movement.
Stages of physiologic tooth eruption
1.Pre-Eruptive tooth movement
Pre-Eruptive tooth movement
2.Eruptive tooth movement.
3.Post-Eruptive tooth movement
Theories of tooth eruption.
COMPENSATION FOR OCCLUSAL WEAR
active pasive eruption
demerits of theories of eruption
Clinical consideration



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Tooth eruption

  1. 1. Presented by Dr.Vedangi Mohite I MDS Dept.of Paedodontics & Preventive Dentistry. Tooth Eruption Part –I
  2. 2.  Introduction.  Stages of tooth eruption.  Histology of tooth movement.  Theories of tooth eruption.  Clinical consideration contents
  3. 3. Introdution  Tooth eruption is defined as , “The movement of a tooth from its site of development within the jaws to its position of function within the oral cavity .” -According to Massler and Schour, 1941.  Eruption is only a part of the total pattern of physiologic tooth movement, because teeth also undergoes various complex movements. Erumpere (Latin)
  4. 4.  Brodie (1934) described the movement of the crypt toward the gingival crest and then the crypt would rupture as the tooth emerged from the gingiva.  Carlson (1944) separated the eruption of a tooth into three phases. 1. The formation of the crown of the tooth. 2. The period of rapid eruption 3. The phase in which the occlusal plane is moving as a unit. Authors dated back in history attempted to study eruption. Hoelscher, Benjamin Charles. "Passive eruption patterns in first molars." MS (Master of Science) thesis, University of Iowa, 2011.
  5. 5.  Weinmann (1941) broke the process up into three phases. 1. The pre-emergence as the tooth makes its way and just pierces through the gingiva. 2. The emergence through the tissue to contact with the opposing tooth. 3. The post occlusal contact phase in which the tooth would continue to erupt over time as attrition occurrs Authors dated back in history attempted to study eruption. Hoelscher, Benjamin Charles. "Passive eruption patterns in first molars." MS (Master of Science) thesis, University of Iowa, 2011.
  6. 6.  Darling and Levers (1975) expanded on Carlson’s theory.  They began with an observation that the dental follicle grows in a concentric fashion.  This is the first phase of eruption as the tooth is growing and enlarging equally towards the occlusal plane and the lower border of the mandible.  Once the root begins to form, the tooth begins to move towards the occlusal plane. This is the beginning of active eruption. Authors dated back in history attempted to study eruption. Hoelscher, Benjamin Charles. "Passive eruption patterns in first molars." MS (Master of Science) thesis, University of Iowa, 2011.
  7. 7.  The second phase of active eruption begins during the adolescent growth spurt and will continue for a period of years.  The third phase begins When the tooth comes into contact with its opposing tooth and it stops erupting  Around 18 years of age, the teeth settle into an equilibrium phase in which the occlusal relationship is set. Authors dated back in history attempted to study eruption. Hoelscher, Benjamin Charles. "Passive eruption patterns in first molars." MS (Master of Science) thesis, University of Iowa, 2011.
  8. 8.  Steedle and Proffit (1985), through a histological study, agreed with the centred growth of the dental follicle.  Bjork and Skieller (1955, 1972) used implanted metallic markers to study eruption. Authors dated back in history attempted to study eruption. Hoelscher, Benjamin Charles. "Passive eruption patterns in first molars." MS (Master of Science) thesis, University of Iowa, 2011.
  9. 9.  The jaws of an infant are smaller in size and can accommodate only a few small teeth.  However, the larger jaws of an adult can accommodate more number and bigger sized teeth.  This accommodation is accomplished with two sets of dentitions. Intoduction Tencate’s Textbook of Oral histology(8th Edition)
  10. 10.  The development of teeth takes place within the tissues of the jaw.  Considerable movement is required to bring the teeth into a functional position.  The movements of teeth are complex and may be described in 3 stages. Introduction Tencate’s Textbook of Oral histology(8th Edition)
  11. 11.  1.Pre-Eruptive tooth movement  2.Eruptive tooth movement.  3.Post-Eruptive tooth movement Stages of physiologic tooth eruption Tencate’s Textbook of Oral histology(8th Edition)
  12. 12.  The movement made by the deciduous and the permanent tooth germs within tissues of the jaw before they begin to erupt. Pre eruptive tooth movement Tencate’s Textbook of Oral histology(8th Edition)
  13. 13.  When the deciduous tooth germs first differentiate, they are extremely small, and a good deal of space is available for them in the developing jaw.  Due to their rapid growth, crowding results.  This crowding is then relieved by growth of the jaws in length, which permits drifting of the tooth germs. Pre eruptive tooth movement Tencate’s Textbook of Oral histology(8th Edition)
  14. 14.  The deciduous second molar tooth germs moves backwards and the anterior germs move forward to , alleviate this crowding.  At the same time the tooth germs are moving bodily outward and upward with the increasing length ,width and height of the jaws. Pre eruptive tooth movement (deciduous) Tencate’s Textbook of Oral histology(8th Edition)
  15. 15.  Tooth movement in the permanent teeth with their deciduous predecessors occurs before they reach the position from which they will erupt.  The permanent tooth germs develop from the lingual aspect of their deciduous predecessors, in the same bony crypt.  From this position they shift considerably as the jaws develop. Pre eruptive tooth movement (Permanent) Tencate’s Textbook of Oral histology(8th Edition)
  16. 16. Pre eruptive tooth movement (Permanent teeth with deciduous predecessor) New born 9 months3 months 2 years Orban’s Textbook of oral histology and embryology (13th edition).
  17. 17. Pre eruptive tooth movement (Permanent teeth with deciduous predecessor) 4 ½ years 6 years 9 years Orban’s Textbook of oral histology and embryology (13th edition).
  18. 18.  The permanent molar tooth germs, which have no predecessors, develop from the backward extension of the dental lamina Pre eruptive tooth movement (Permanent teeth without deciduous predecessor) Tencate’s Textbook of Oral histology(8th Edition)
  19. 19.  In the upper jaw , the molar tooth germs develop first, with their occlusal surfaces facing distally.  Then they swing into position only when the maxilla has grown sufficiently to provide room for such movement Pre eruptive tooth movement (Permanent maxillary molars) Orban’s Textbook of oral histology and embryology (13th edition).
  20. 20.  In the mandible the permanent molars develop with their axes showing a mesial inclination, which becomes vertical as the jaw growth increases. Pre eruptive tooth movement (Permanent mandibular molars) Orban’s Textbook of oral histology and embryology (13th edition).
  21. 21.  The pre eruptive movements of teeth are a combination of two factors:  (1) Total bodily movement of the tooth germ  (2) growth in which one part of the tooth germ remains fixed while the rest continues to grow .  This growth explains, how the deciduous incisors maintain their position relative to the oral mucosa as the jaws increase in height.
  22. 22.  During eccentric growth, only bony resorption occurs, thus altering the shape of the crypt to accommodate the altering shape of the tooth germ.  During bodily movement in a mesial direction, bone resorption occurs on the mesial surface of the crypt wall, and bone deposition occurs on the distal wall. Bony remodelling within the crypt wall. Orban’s Textbook of oral histology and embryology (13th edition).
  23. 23. The movement of the tooth after its appearance in the oral cavity till it attains the functional position. Prefunctional eruptive tooth movement – Orban’s Textbook of oral histology and embryology (13th edition).
  24. 24.  It is the movement of tooth from its developmental position within the jaw to its final functional position in the occlusal plane.  The principal direction of movement is axial to keep pace with the increase in height of the jaws.  It involves both the tooth and its socket and ceases when jaw growth is completed. Eruptive tooth movement
  25. 25.  Movements made by the tooth after it has reached its functional position in the occlusal plane.  They are divided into three categories- . Post Eruptive tooth movement Accomodation for growth Compensation for occlusal wear Accomodation for interproximal wear
  26. 26.  ACCOMMODATION FOR GROWTH –  Mostly occurs between 14 and 18 years by formation of new bone at the alveolar crest and base of socket to keep pace with increasing height of jaws. Post Eruptive tooth movement
  27. 27.  COMPENSATION FOR OCCLUSAL WEAR –  Compensation primarily occurs by continuous deposition of cementum around the apex of the tooth.  However, this deposition occurs only after the tooth moves. Post Eruptive tooth movement
  28. 28.  The axial post eruptive movements are made when the apices of the permanent lower molars and second premolar are formed fully which indicates again that root growth is not the factor responsible for axial eruptive tooth movement and further emphasizes the role of the PDL. COMPENSATION FOR OCCLUSAL WEAR –
  29. 29.  ACCOMMODATION FOR INTERPROXIMAL WEAR -  Compensated by mesial or approximal drift.  Proximal wear can decrease the arch length by as much as 7 mm.  The mesial drift involves the contraction of trans septal ligament and an anteriorly directed force Post Eruptive tooth movement
  30. 30.  The forces causing mesial drift are multifactorial and include  an anterior component of occlusal force  contraction of the trans septal ligament between teeth  soft tissue pressure. Accommodation for interproximal wear - Tencate’s Textbook of Oral histology(8th Edition)
  31. 31. When teeth are brought into contact an anteriorly directed force is generated. This anterior force is the result of the mesial inclination of most teeth and the summation of intercuspal planes (producing a forward-directed force) In the case of incisors, which are inclined labially, any anterior component of force would be expected to move them in the same direction. Anterior Component of Occlusal Force Tencate’s Textbook of Oral histology(8th Edition)
  32. 32. The incisors move mesially, this can be explained by the billiard ball analogy
  33. 33.  When cusps are selectively ground, the direction of occlusal force can be enhanced or reversed.  When opposing teeth were removed, the mesial migration of teeth was slowed but not halted, indicating the presence of some other force.  Thus the transseptal fibers of the PDL have been implicated. Anterior Component of Occlusal Force Tencate’s Textbook of Oral histology(8th Edition)
  34. 34.  The PDL plays an important role in maintaining tooth position.  The transseptal fibers (running between adjacent teeth across the alveolar process) draw neighboring teeth together and maintain them in contact. Contraction of the trans septal ligament between teeth Orban’s Textbook of oral histology and embryology (13th edition).
  35. 35.  If a tooth is bisected, the two halves moved away from each other, but if the trans-septal ligament is previously removed, this separation does not occur.  By disking away the proximal contacts, room is made to permit mesial drift, and the teeth begin to move to re establish contact.  If teeth are ground out of occlusal contact, the rate of drift is slowed but not stopped.  The conclusion must be that mesial drift is achieved by contraction of tran sseptal fibers and enhanced by occlusal forces. Orban’s Textbook of oral histology and embryology (13th edition).
  36. 36.  The pressures generated by the cheeks and tongue may push teeth mesially.  When such pressures are eliminated, by constructing an acrylic dome over the teeth, mesial drift still occurs, which suggests that soft tissue pressure does not play a major role in creating mesial drift.  Nevertheless, soft tissue pressure does influence tooth position, even if it does not cause tooth movement. Soft Tissue Pressures
  37. 37.  In 1927 Gottlieb wrote on the gingival margin that in reference to the eruption of teeth,  Newman (1979), studied 190 skulls and found that as attrition occurs so does eruption  He determined that the rates of eruption and attrition were similar. Active Tooth Eruption “Just for how long it continues we have been so far unable to discover (but) I would say that it is a fact that the teeth erupt continuously.” Hoelscher, Benjamin Charles. "Passive eruption patterns in first molars." MS (Master of Science) thesis, University of Iowa, 2011.
  38. 38.  It is the movement of the teeth in the direction of the occlusal plane.  Apposition of bone accompanies active eruption.  The distance between the apical end of the junctional epithelium and the crest of the alveolus remains constant throughout continuous eruption.(1.07mm) Active Tooth Eruption Carranza’s Textbook of Periodontology.11th Edition(2011)
  39. 39.  Gottlieb (1927) laid out the theory of “passive eruption” to theorize the connection of the gingival margin to the tooth was a dynamic association.  Despite the observations and claims, there was little quantitative evidence to support his theories.  However,in 1933, Orban and Gottlieb defined the term “passive as the movement towards the apex of the tooth. Passive Eruption Hoelscher, Benjamin Charles. "Passive eruption patterns in first molars." MS (Master of Science) thesis, University of Iowa, 2011.
  40. 40.  Passive eruption is defined as, "The exposure of teeth by apical migration of gingiva.” Passive Eruption Carranza’s Textbook of Periodontology.11th Edition(2011)
  41. 41. Stages of passive eruption Carranza’s Textbook of Periodontology.11th Edition(2011)
  42. 42.  According to Goldman and Cohen,1968 it is defined as, “The failure of the tissue to adequately recede to a level apical to the cervical convexity of the crown.” Altered passive eruption Alpiste-Illueca F. Altered passive eruption (APE): A little -known clinical situation. Med Oral Patol Oral Cir Bucal. 2011 Jan 1;16 (1)
  43. 43. Stages of altered passive eruption
  44. 44. Noyes, F.B, Schour, I, Noyes, H.J. Dental Histology and Embryology. Lea & Febiger , Philadelphia; 1938.
  45. 45. Histologic features 1.Pre eruptive phase 2. Eruptive phase 3. Post eruptive phase
  46. 46.  This phase involves growth of the tooth germ and demands remodelling of the bony wall of the crypt.  It is also indicated that normal skeletal morphogenesis might be involved in determining tooth position.  The intraosseous phase of tooth eruption can be considered as a process of bone remodeling. Pre eruptive phase Orban’s Textbook of oral histology and embryology (13th edition).
  47. 47. Eruptive phase Root formation Periodontal Ligament Dentogingival junction Tencate’s Textbook of Oral histology(8th Edition)
  48. 48. Root formation initiated by growth of HERs, which initiates the differentiation of odontoblasts from the dental papilla The odontoblasts then form root dentin, bringing about an overall increase in length of the tooth Shortly after the onset of root formation cementum, periodontal ligament, and the bone lining the crypt wall are formed
  49. 49. Formation of Periodontal ligament  The periodontal ligament (PDL) develops only after root formation has been initiated.  When established, the PDL must be remodelled to accommodate continued eruptive tooth movement.  The remodelling of PDL fiber bundles is achieved by the fibroblasts, which simultaneously synthesize and degrade the collagen fibrils as required across the entire extent of the ligament
  50. 50. (A) Phagocytosis of collagen fibril. (C) Degradation continues in phagolysosomes (B) lysosomal activity Three electron micrographs illustrating the fibroblast remodeling and turnover. Orban’s Textbook of oral histology and embryology 13th edition.
  51. 51.  The fibro cellular follicle surrounding a successional tooth retains its connection with the lamina propria of the oral mucous membrane by means of a strand of fibrous tissue containing remnants of the dental lamina, known as the gubernacular cord.  They can be identified in the jaws on the lingual aspects of the deciduous teeth. Gubernacular cord. Tencate’s Textbook of Oral histology(8th Edition)
  52. 52.  After removal of any overlying bone there is loss of CT between the REE covering the crown of the tooth and the overlying oral epithelium.  The epithelium begins to proliferate and migrate into the disorganized connective tissue.  The central cells degenerate and form an form an epithelium- lined canal through which the tooth erupts without erupts without any hemorrhage.  This epithelial cell mass is also involved in the formation of the dentogingival junction . Formation of dentogingival junction Orban’s Textbook of oral histology and embryology 13th edition.
  53. 53.  This rate persists until the tooth reaches the occlusal plane, indicating that soft connective tissue provides little resistance to tooth movement Rate of eruption
  54. 54.  In this phase the tooth makes movements primarily to accommodate the growth of the jaws.  It occurs most actively between the ages of 14 and 18 and is associated with condylar growth,  Bone deposition occurs at the alveolar crest and on the socket floor .  The same forces responsible for eruptive tooth movement achieve axial post eruptive movement, with bone deposition occurring later. Post eruptive Phase Orban’s Textbook of oral histology and embryology 13th edition.
  55. 55. 6. Dental follicle theory (MARKS & CAHILL 1984) 7. Vascular pressure theory (Sutton & Graze 1985) 8. Pressure from muscular action 9. Resorption of alveolar crest 10. Hormonal theory 1. Cellular proliferation theory(eidmann 1923) 2. Bone remodelling theory (BRASH 1928) 3. Root elongation theory(hammock ligament theory (HUNTER 1929) 4. Pulp constriction theory (V.KORFF 1935) 5. Periodontal ligament contraction theory (THOMAS 1967) Theories of tooth eruption
  56. 56.  Noyes pointed out that osmotic pressure & forces resulting from cellular proliferation in pulp & surrounding tissues may account for eruption of teeth  The cellular proliferation in the marrow spaces surrounding the tooth causes a tension that in turn causes the eruption.  However, the amount of cellular proliferation found in these spaces can hardly account for the relatively tremendous force of eruption. Cellular proliferation theory(eidmann 1923) Masseler M,Schour I .Studies in tooth development: theorles of eruption:Original article1941,From the Department of Histology, College of Dentistry,University of Illinois.
  57. 57.  This theory fails to explain 1. The eruption of teeth long after the proliferation of Her twig's epithelial sheath is completed and its cells are disintegrated. 2. The eruption of the rat incisor after Hertwig’s epithelial sheath is removed surgically Evidence against the theory Masseler M,Schour I .Studies in tooth development: theorles of eruption:Original article1941,From the Department of Histology, College of Dentistry,University of Illinois.
  58. 58.  The inherent growth pattern of the mandible or maxilla supposedly moves teeth by the selective deposition and resorption of bone in the immediate neighbourhood of the tooth. Bone remodelling theory (BRASH 1928) Tencate’s Textbook of Oral histology(8th Edition)
  59. 59.  According to Hermann and Nessel (1928) the growth of the alveolar bone might push the tooth out of its alveolus and into the oral cavity.  However, x-ray and histologic sections showed that the bone does not actually touch the tooth.  In addition, this mechanism can operate only upon single conical roots. Bone remodelling theory (BRASH 1928) Masseler M,Schour I .Studies in tooth development: theorles of eruption:Original article1941,From the Department of Histology, College of Dentistry,University of Illinois.
  60. 60.  According to Brash , “the teeth are purely passive objects whose eruption is incidental to the growth of the alveolar bone”.  The growth of the alveolar process is the result of the eruption of the teeth and its existence is entirely dependent upon the presence of the teeth. Bone remodelling theory (BRASH 1928) Masseler M,Schour I .Studies in tooth development: theorles of eruption:Original article1941,From the Department of Histology, College of Dentistry,University of Illinois.
  61. 61.  From the works of Oppenheim (1932), it was apparent that the alveolar bone is formed in response to tooth movement.  When a tooth moves it pulls upon the bone through the embedded periodontal fibers.  The bone does not push or pull the tooth into eruption.  The orientation of the bony trabeculae shows that eruption provides the stimulus for the growth of the alveolar process Bone remodelling theory (BRASH 1928)
  62. 62.  These theories are invalid on the following bases :- 1. When deciduous molar are prematurely lost , the underlying premolar often jumps out of its crypt and into occlusion.  X-ray examination shows that in such cases the eruption is so rapid that the growth of the bone does not catch up with the eruption of the tooth for some time. Evidence against this theory
  63. 63. 2. Histologic examination showed that the orientation of the trabeculae toward the direction of eruption, indicating the fact that alveolar bone formation is a response to eruption of the teeth. Evidence against this theory 1, Pulp 2, dentin 3, periodontal membrane 4. spicules of alveolar bone.
  64. 64.  3. Churchill et al pointed out that in certain dermoid cysts, the teeth may erupt in the absence of a bony base. Evidence against this theory Masseler M,Schour I .Studies in tooth development: theorles of eruption:Original article1941,From the Department of Histology, College of Dentistry,University of Illinois.
  65. 65.  In 1929 Hunter attributed to the mechanism of root formation.  This theory states that the proliferating root formation results in an eruptive force.  The apical growth gets translated into the occlusal movement and requires a fixed base.  However, no such fixed base exist.  The bone at the base of the socket cannot act as a fixed base because pressure on the bone results into resorption Root elongation theory (Hunter 1929) Orban’s Textbook of oral histology and embryology 13th edition.
  66. 66. If the occlusal movement is prevented, resorption of the bone occurs at the base of the socket. Root elongation theory (Hunter 1929)
  67. 67.  The advocates of this theory then postulated the existence of a ligament.  First proposed by Harry Sicher “The cushion-hammock ligament”, straddling the base of the of the socket from one bony wall to the other like a sling.  But the structure described as the cushion hammock ligament has no bony insertion.  Thus it cannot act as a fixed base. Root elongation theory (Hunter 1929) Orban’s Textbook of oral histology and embryology 13th edition.
  68. 68.  Evidence for Theory.-  Root of tooth elongates as crown erupts into the oral cavity.  This evidence, however, is only circumstantial. Clinical Evaluation of the root elongation theory
  69. 69.  Rootless teeth often erupt without the concomitant elongation of the root.  This condition can be seen as follows Evidence Against this Theory:
  70. 70.  IOPA of a permanent upper premolar shows the lack of root formation  The dentine growth and pulpal constriction  The failure of the alveolar bone to keep up with the tooth and the wide periapical space between tooth and bone. 1.The premature loss of the deciduous predecessors Masseler M,Schour I .Studies in tooth development: theorles of eruption:Original article1941,From the Department of Histology, College of Dentistry,University of Illinois.
  71. 71.  Orban in 1930 indicated that HERs remains at a relatively fixed point within the jaw during the eruption of the tooth.  This might indicate that eruption results from the proliferation of HERs pushing the crown occlusally.  However he also stated that such a relation is probably coincidental. Futher he stated that, A bicuspid tooth will not erupt for sometimes, after the loss of its predecessor. Its eruption may in fact be markedly retarded. In such cases it is found that the soft tissue overlying the tooth has become fibrotic and dense and offers a mechanical obstruction . Thus eruption of a bicuspid may sometimes be delayed instead of accelerated following the extraction of a deciduous tooth Orban, B.: Dental Histology and Embryology, Philadelphia, 1929, P. Blakiston’s Son&co.
  72. 72.  IOPA showing a markedly deficient amount of root formation.  Although the eruption time of the teeth was normal. 2.In cases of congenital lack or deficient of root formation Masseler M,Schour I .Studies in tooth development: theorles of eruption:Original article1941,From the Department of Histology, College of Dentistry,University of Illinois.
  73. 73. Pre treatment (age, 10years) showing the rootless left permanent canine at age 7 years showing postsurgical repair of the double mandibular fractures with rigid fixation. Shapiraa Y and Mladen M.Rootless eruption of a mandibular permanent canine.Am J Orthod Dentofacial Orthop 2011;139:563-6
  74. 74.  IOPA of a fractured upper right central incisor in a lo-year-old child.  Fig A, X-ray taken about two months after the accident.  Fig B, X-ray taken nine months later.  Supra-eruption seen in B, probably caused by an inflammatory reaction at the site of fracture between the coronal and apical segments. 3.The eruption of the incisal segment of a tooth after fracture
  75. 75. Submerged teeth often continue the formation of their roots but do not erupt. Supra-eruption occurs when its antagonist is lost , long after root formation is completed. The distance travelled by some teeth during eruption is much greater than the total length of their roots Evidence Against Theory:
  76. 76. Evidence Against Theory: During eruption, the tooth changes its inclination and direction . The total length of the root is attained after clinical eruption of the tooth. About 4/5th of the root is completed when eruption of the tooth is clinically completed. The root of the tooth does not reach the bottom of the alveolus during eruption The root does not push against any solid structure, but appears, rather, to be pushed in an occlusal direction.
  77. 77. Conclusion  There is no convincing evidence to support the theory and there are many clinical and experimental evidences against this theory.  The theory is therefore inadequate.  However, although the elongation of the root cannot be the only factor, the evidence does not exclude it from being one of many factors operating during normal eruption. Masseler M,Schour I .Studies in tooth development: theorles of eruption:Original article1941,From the Department of Histology, College of Dentistry,University of Illinois.
  78. 78.  The growth of the root dentin and the subsequent constriction of the pulp may cause sufficient pressure to move the tooth occlusally.  However Tomes pointed out that this theory fails to explain the eruption of rootless or fully formed teeth. Pulp constriction theory (V.Korff 1935) Masseler M,Schour I .Studies in tooth development: theorles of eruption:Original article1941,From the Department of Histology, College of Dentistry,University of Illinois.
  79. 79. Evidence for the theory:-  The pulp is progressively constricted by growth of root dentin as the eruption of the tooth occurs.  However this evidence is not sufficient. Clinical Evaluation of this theory: Masseler M,Schour I .Studies in tooth development: theorles of eruption:Original article1941,From the Department of Histology, College of Dentistry,University of Illinois.
  80. 80. 1. Pulp less teeth often erupt at the same rate as their normal neighbours.  IOPA shows the supra- eruption of a pulp less central incisor in a 10 year old.  Both central incisors were at the same incisal level at the time of pulp extirpation. Evidence Against Theory
  81. 81. 2. Submerged molars and upper cuspids often erupt long after dentine formation is completed even when the pulps are fully enclosed and the apical foramen is almost obliterated. Evidence Against Theory IOPA of a cuspid in active eruption. The cuspid came into clinical occlusion about three years after the x-ray was taken. No orthodontic measures were used.
  82. 82. 4.Supra-eruption will occur when the antagonist is lost, long after dentin formation has ended and the apical foramen is quite small, even in pulp less teeth. 3.Premolar will often “jump” into occlusion after the premature loss of the deciduous molar without any appreciable growth of dentine or pulpal constriction Evidence Against Theory
  83. 83.  The theory that the pressure derived from pulpal constriction incident to dentin growth causes the eruption of the tooth is itself inadequate.  Since it fails to explain many factors in eruption and is supported by no actual evidence.  However, the evidence against the theory is not sufficiently conclusive to eliminate entirely pulpal constriction as a possible factor in normal eruption. Conclusion Masseler M,Schour I .Studies in tooth development: theorles of eruption:Original article1941,From the Department of Histology, College of Dentistry,University of Illinois.
  84. 84.  This theory states that the eruptive force resides in the dental follicle–periodontal ligament complex.  The eruption of teeth could be brought about by a combination of events involving a force initiated by the fibroblast Periodontal ligament contraction theory (Thomas 1967)
  85. 85.  Tissue culture experiments have shown that PDL fibroblasts are able to contract a collagen-gel, which in turn brings about movement of the root tissue attached .  Thus they have the ability to contract and transmit a contractile force to the extracellular environment and in particular to the collagen fiber bundles . PDL Fibroblasts Orban’s Textbook of oral histology and embryology 13th edition.
  86. 86. PDL Fibroblasts fibroblasts possess contractile filaments exhibit fibronexuses forces transmitted to the collagen fiber bundles. Orban’s Textbook of oral histology and embryology 13th edition.
  87. 87.  These fibre's remodel and are inclined at the correct angle to bring about eruptive movement.  This angulation of the ligament fibre bundles is a prerequisite for tooth movement, and the orientation is believed to be established by the developing root. Periodontal ligament fibres Orban’s Textbook of oral histology and embryology 13th edition.
  88. 88.  A simple analogy is the sailor (fibroblast) pulling on a rope (collagen) attached to a sail (tooth). To move the sail the sailor must remain stationary and pull on the rope (contraction) and coil it on the deck (collagen remodelling). Analogy for the fibroblast contraction Orban’s Textbook of oral histology and embryology 13th edition.
  89. 89. Evidence supporting the theory  The findings that support the ligament traction theory come mainly from the experiments conducted in continuously erupting rodent teeth.  In humans, having limited eruption, fibres of dental follicle are not attached to the alveolar bone and are not oriented to move the teeth during the intraosseous phase.  But, once the tooth has appeared in the oral cavity and before it attains its final position , the periodontal ligament fibres exert the tractional force due to its attachment to the alveolar bone and to its orientation Clinical Evaluation
  90. 90.  The existence of fibronexus between fibroblast and fibres is questioned.  These junctions appear to have desmosomes and having no microfilament bundles.  Therefore these cells would not be able to transmit a tractional force required to pull the tooth in eruption.  Studies of tritium labeled with thymidine show that the periodontal ligament fibroblast move occlusally at a rate equal to the rate of eruption, doubts have been expressed whether the cells are actively moving or they are passively transported. Evidence against the theory Orban’s Textbook of oral histology and embryology 13th edition.
  91. 91.  Histologic examination of the periodontal fibres and the bony trabeculae during eruption showed that the migrating tooth is pulling upon the Periodontal fibres. Evidence against the theory During eruption the tooth draws the fibres of the dental periosteum in the direction of movement F, Fibres.R,root.
  92. 92.  Any theory which supposes that the periodontal tissues are the active agents in pulling or pushing upon the tooth to cause eruption is unsupported by factual evidence.  This does not entirely eliminate, however, the growth of the periodontal tissues as a possible factor in aiding the normal eruption of the tooth. Conclusion Masseler M,Schour I .Studies in tooth development: theorles of eruption:Original article1941,From the Department of Histology, College of Dentistry,University of Illinois.
  93. 93.  reduced dental epithelium  a cascade of intercellular signals  recruit osteoclasts to the follicle.  Tooth eruption Dental follicle theory (MARKS & CAHILL 1984) Tencate’s Textbook of Oral histology(8th Edition)
  94. 94.  Pattern cellular activity involving the REE and the DF associated with tooth eruption, facilitates connective tissue degradation and bone resorption as the tooth erupts. Dental follicle theory (MARKS & CAHILL 1984)
  95. 95.  Major proof is when a tooth is removed without disturbing its follicle, an eruptive pathway still forms within bone.  If the dental follicle is removed , no eruption pathway forms.  This establishes the absolute requirement for dental follicle to achieve bony remodelling and tooth eruption, for it is the follicle that provides the source for new bone-forming cells and conduit for osteoclasts through its vascular supply. Dental follicle theory (MARKS & CAHILL 1984) Orban’s Textbook of oral histology and embryology 13th edition.
  96. 96. Conclusion  In summary, eruptive movement is multifactorial, like vascular pressure at the apex along with contractile force generated by the dental follicle playing an important part and bone formation and resorption facilitating the process. Orban’s Textbook of oral histology and embryology 13th edition.
  97. 97. Vascular pressure theory (Sutton & Graze 1985) in hydrostatic pressure induced by hypotensive drugs. the rate of eruption while stimulation of sympathetic nerves, which cause vasoconstriction and In the hydrostatic pressure, and the rate of eruption. It is known that teeth move in synchrony with the arterial pulse, so local volume changes can produce limited tooth movement.
  98. 98.  It has been observed that the number of fenestrated capillaries, increase with the eruption .  More numbers of fenestrated capillaries are seen near the base of the crypt than at alveolar crest. Vascular pressure theory (Sutton & Graze 1985) fenestrated capillaries
  99. 99.  Injection of 2% lignocaine with adrenaline above the root of erupting premolars causes a burst in the increase of eruption of teeth receiving the injection with or without vasoconstrictor.  However, the teeth receiving vasoconstrictor showed decrease in eruption rate, suggesting that vascular changes affect prefunctional eruption. Vascular pressure theory (Sutton & Graze 1985)
  100. 100.  Evidence supporting the theory:- 1. Submerged teeth often erupt under the influence of hyperemia induced by mechanical irritations. 2.The hyperemia in periodontitis causes a supra-eruption of the teeth. Clinical Evaluation
  101. 101. 3. According to Fischer et al there is a marked hyperemia or congestion of the periodontal tissues which normally accompanies the eruption of teeth in children  However this does not prove a cause and effect between the two.  The reverse may be the true course of events i.e, eruption of the teeth may cause a congestion of the periodontal tissues. Evidence supporting the theory:-
  102. 102.  The pressure exerted is not enough to help in eruption of teeth.  Teeth erupt even when the vascular supply is cut. Conclusion.-  There is considerable evidence that links the vascularity of the periodontal tissues to the eruption of the teeth.  Evidence to the contrary is not apparent. Evidence against the theory
  103. 103. Pressure from muscular action  Berten et al suggested that action of musculature of cheeks & lips upon alveolar process might serve to squeeze crown of tooth out into oral cavity like a pumpkin seed from between fingers.  This process continuous until the teeth is in occlusion.
  104. 104. 1. The teeth erupt which erupt lingual to the arch are under no muscular action of the cheeks and lips. Evidence against the theory Masseler M,Schour I .Studies in tooth development: theorles of eruption:Original article1941,From the Department of Histology, College of Dentistry,University of Illinois.
  105. 105.  Mouth breathers with notoriously weak action of the cheek and lip musculature show a relatively increased or supra-eruption of the clinical crowns of the teeth.  while people with strong musculature and powerful bites show much less erupted clinical crowns of the teeth.
  106. 106.  Teeth also erupt even in cases of unilateral facial paralysis  The eruption of impacted teeth proceeds in a horizontal instead of a vertical direction. Evidence against the theory
  107. 107.  The resorption of the alveolar crest exposes crown of tooth into oral cavity.  This theory is not tenable since histological examination shows that alveolar crest is the site of most rapid & continuous growth of bone. Resorption of alveolar crest
  108. 108.  Arthur Keith suggested that hormones secreted by thyroids & pituitary glands might govern eruption of teeth .  However this theory does not explain mechanism of eruption of teeth & only points out fact that hormones may affect eruption of teeth. Hormonal theory Masseler M,Schour I .Studies in tooth development: theorles of eruption:Original article1941,From the Department of Histology, College of Dentistry,University of Illinois.
  109. 109. Cellular and molecular events in eruption
  110. 110. Cellular events of eruption
  111. 111.  The dental follicle contains genes that encode expression of various transcription factors and involve series of signaling interaction between the dental follicle cells and cells of bony crypts.  Determination of the molecules that may be required for eruption–  EGF (epidermal growth factor )  TGF α (transforming growth factor )  Colony stimulating factor 1 MOLECULAR EVENTS ↑ in incisor eruption ↑ in molar eruption
  112. 112. Molecular determinants of tooth eruption
  113. 113. Result Enhance Inhibition
  114. 114.  Chronos- time &  Logos- study  Chronology is a study which deals with the timings of the various stages of tooth development, starting with initiation of the first dental tissue laid down to the emergence of tooth into the oral cavity and its completion of calcification. Chronology of tooth eruption
  115. 115. Chronology of deciduous dentition
  116. 116. Chronology of permanent dentition-maxillary
  117. 117. Chronology of permanent dentition-mandibular
  118. 118. Sequence of Eruption
  119. 119.  According to Carlos and Gittelsohn et al  The average eruption time of the lower central incisors was earlier than that of the first molars by about 1½ months in both boys and girls.  In girls- mandibular canine erupt before the maxillary and mandibular first premolars  In boys- maxillary & mandibular first premolars erupted before mandibular canine Variations in sequence of eruption
  120. 120.  Teeth follow a strict time schedule in eruption, the mixed dentition period, help in assessment of dental age and this along with skeletal age is an index of maturity in development of the individual.  Radiographic examination of the jaws of children would show the extentof crown formation, amount of root development, all of which aid in a more correct assessment of the dental age. Assessment of the dental age.
  121. 121.  Posen et al, after reviewing the records of children who had undergone unilateral extraction of primary molars, came to the following conclusions:  Eruption of the premolar teeth is delayed in children who lose primary molars at 4 or 5 years of age and before.  If extraction of the primary molars occurs after the age of 5 years, there is a decrease in the delay of premolar eruption.  At 8, 9, and 10 years of age, premolar eruption is greatly accelerated. Influence of premature loss of primary molars on eruption of their successors
  122. 122.  Hartsfield stated that premature loss of teeth associated with systemic disease usually results from some change in the immune system or connective tissue.  The most common conditions associated are hypophosphatasia and early-onset periodontitis Premature loss of teeth
  123. 123.  Delays in dental eruption can be familial or can occur with conditions such as: Delayed eruption
  124. 124. Suri, Gagari, and Vastardis.American Journal of Orthodontics and Dentofacial Orthopedics .126;4(234-39)
  125. 125. Suri, Gagari, and Vastardis.American Journal of Orthodontics and Dentofacial Orthopedics .126;4(234-39)
  126. 126.  Eruption occurring in an abnormal position or place  Unknown causes but probably genetic.  Arch length inadequacy  Can cause: o Resorption of a primary tooth other than the one it is supposed to replace o Resorption of an adjacent permanent tooth • Commnest: lateral incisor, maxillary first molar and canine Ectopic eruption Shafer’s text book of oral and maxillofacial pathology( 7th edition)
  127. 127.  The primary teeth may or may not have undergone root resorption and may be held only by soft tissues.  It is common for mandibular permanent incisors to erupt lingually, and this pattern should be considered essentially normal.  The tongue and continued alveolar growth seem to play an important role in influencing the permanent incisors into a more normal position with time. Lingual eruption of mandibular permanent incisors
  128. 128.  Although there may be insufficient room in the arch for the newly erupted permanent tooth, its position will improve over several months.  In some cases there is justification for removal of the corresponding primary tooth.  Extraction of the primary teeth is not recommended, Lingual eruption of mandibular permanent incisors
  129. 129.  Anodontia is the complete absence of the tooth.  It can be complete or partial.  Three forms- 1.True Anodontia 2.False Anodontia 3.Pseudo Anodontia Anodontia MUTATION OF PAX9 MSX1 AND AXIN2 Shafer’s text book of oral and maxillofacial pathology( 7th edition)
  130. 130. o Local causes:  Mucosal barrier  Supernumerary teeth  Injuries o 0ther-  Genetic  Endocrinal deficiencies o T/t: It is advisable to give minor incision to facilitate eruption if no association of ankylosis Impacted Teeth Shafer’s text book of oral and maxillofacial pathology( 7th edition)
  131. 131.  Submerged teeth are deciduous teeth, most commonly mandibular 2nd molars , that have undergone a variable degree of root resorption and then have ankylosed to the bone.  This process prevents their exfoliation and subsequent replacement by permanent teeth.  After the permanent teeth is erupted, the ankylosed appears to be submerged below the level of occlusion. Ankylosed teeth Shafer’s text book of oral and maxillofacial pathology( 7th edition)
  132. 132.  A primary tooth still present when 3/4 of root of permanent successor has formed  Possibly some root of primary tooth is still present  T/t :Extraction Over retained deciduous teeth
  133. 133.  The moment a tooth breaks through the oral epithelium, an acute inflammatory response occurs in the connective tissue adjacent to the tooth.  In infants these symptoms are popularly called “teething.”  Local signs: o Hyperemia of the overlying mucosa o Patches of erythema on the cheeks  Problems associated : o Eruption hematoma Ectopic eruption o Transposition Eruption sequestrum Teething
  134. 134.  Illingworth failed to produce evidence that teething causes fever, convulsions, bronchitis, or diarrhoea.  His findings are supported by Tasanen’s unique study of teething, in which 192 tooth eruptions were observed in 126 infants and 107 controls.  All the babies were seen on the day of the eruption of the tooth, and records were kept of – the temperature, incidence of infection, erythrocyte sedimentation rate, white blood cell count, colour of the mucosa, sensitivity of the tissue covering the erupting tooth, and pain resulting from pressure on the tooth. M P Ashley, Personal View: It's only teething... A report of the myths and modern approaches to teething, British Dental Journal, 2001, 191;1(4)
  135. 135. teething does not increase Teething does cause the incidence of infection, rise in temperature, erythrocyte sedimentation rate white blood cell count does not cause diarrhoea, cough, sleep disturbance, daytime restlessness, an increase in the amount of finger sucking or rubbing of the gum, an increase in drooling, and possibly some loss of appetite. Conclusion of the study M P Ashley, Personal View: It's only teething... A report of the myths and modern approaches to teething, British Dental Journal, 2001, 191;1(4)
  136. 136. Eruption cyst  An eruption cyst, or eruption hematoma, is a bluish swelling that occurs on the soft tissue over an erupting tooth.  Forms superficially on the gingiva overlying the involved erupting tooth.  Usually within few days the tooth breaks through the tissue and the hematoma subsides. Neville.Text book of Oral and Maxillofacial Pathology (3rd edition
  137. 137. Eruption sequestrum  Seen as a tiny spicule of nonviable bone overlying the crown of erupting permanent molar just prior or immediately after emergence of the cusp tips.  It’s occurs when the osseous fragment becomes separated from the contiguous bone during eruption of the associated tooth.  It may easily be removed if causing local irritation. Neville.Text book of Oral and Maxillofacial Pathology (3rd edition
  138. 138.  Enamel defects seen in permanent teeth is caused by periapical inflammatory disease of the overlying deciduous tooth.  The altered tooth is called a Turner’s tooth. Turner’s hypoplasia
  139. 139.  The cyst develops as a result of separation of the dental follicle from around the crown of an erupting tooth that is within the soft tissues overlying the alveolar bone.  The epithelial lining of eruption cyst is similar to that of the dentigerous cyst and is considered a superficial dentigerous cyst. ERUPTION CYST (ERUPTION HEMATOMA) Preeti Dhawan et al Eruption cysts: A series of two cases Dent Res J (Isfahan). 2012 Sep- Oct; 9(5): 647–650
  140. 140.  The teeth present at the time of birth are termed as, “natal teeth” & “neonatal teeth” if they erupt during the first month of birth.  In such teeth ,the prism structure is absent in cervical region, dentin is atubular or having giant tubules and cementum absent Natal teeth and Syndrome associated:- 1.Riga-fede disease 2.Pachyonchia congenita 3.Chondro-ectodermal dysplasia 4.Hallerman streiff 5.Ellis Van Crevald
  141. 141. Treatment for natal teeth:  These teeth are defective and their removal is generally recommended, particularly if mobility poses a threat of aspiration.  These teeth also make feeding difficult. Treatment for neonatal teeth:  These teeth are usually normal primary teeth and should be retained.  An x-ray should be taken if possible to confirm that these are not extra teeth. Shafer’s text book of oral and maxillofacial pathology( 7th edition)
  142. 142. Summary  Tooth eruption process is quite a complex and tightly regulated process and many different mechanisms are involved in it.  For the clinicians to treat both the simple as well as the complex dental problems knowledge of proper eruption time is very important.
  143. 143.  A review of the literature shows that the terms “growth” and “eruption” are frequently used interchangeably.  However, the two processes are distinctly different.  The growth of the tooth involves an increase in the size of the tooth substances as a result of cellular activity and eruption of the tooth involves only the migration of the tooth from one position to another.  This is not a growth phenomenon, but the movement of an object-the tooth- through tissues.  Each process is separate and distinct from the other and can easily be dissociated clinically and experimentally. Summary
  144. 144.  Tencate’s Textbook of Oral histology(8th Edition)  Orban’s Textbook of oral histology and embryology (13th edition).  Neville.Text book of Oral and Maxillofacial Pathology (3rd edition  Shafer’s text book of oral and maxillofacial pathology( 7th edition)  Carranza’s Textbook of Periodontology.11th Edition(2011) References
  145. 145.  Alpiste-Illueca F. Altered passive eruption (APE): A little -known clinical situation. Med Oral Patol Oral Cir Bucal. 2011 Jan 1;16 (1)  Noyes, F.B, Schour, I, Noyes, H.J. Dental Histology and Embryology. Lea & Febiger, Philadelphia; 1938.  Hoelscher, Benjamin Charles. "Passive eruption patterns in first molars." MS (Master of Science) thesis, University of Iowa, 2011. References
  146. 146.  Shapiraa Y and Mladen M.Rootless eruption of a mandibular permanent canine.Am J Orthod Dentofacial Orthop 2011;139:563-6  Nakchbandi I. Parathyroid hormone-related protein induces spontaneous osteoclast formation via a paracrine cascadeProc. Natl. Acad. Sci. USA, 2000:97:13(7296-300)  Noyes, F.B, Schour, I, Noyes, H.J. Dental Histology and Embryology. Lea & Febiger, Philadelphia; 1938. References
  147. 147.  M P Ashley, Personal View: It's only teething... A report of the myths and modern approaches to teething, British Dental Journal, 2001, 191;1(4)  Preeti Dhawan et al Eruption cysts: A series of two cases Dent Res J (Isfahan). 2012 Sep-Oct; 9(5): 647–650  Suri, Gagari, and Vastardis.American Journal of Orthodontics and Dentofacial Orthopedics .126;4(234-39)
  148. 148. GRACIAS ALL TEETH ERUPTED

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