Occlusion31 /certified fixed orthodontic courses by Indian dental academy

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Occlusion31 /certified fixed orthodontic courses by Indian dental academy

  1. 1. Development of Occlusion INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com 1
  2. 2. Contents     Introduction Development of concepts of occlusion Evolutionary changes Stages of Occlusion Development         Prenatal Dental development Mouth of Neonate Dev of Dentition from birth to Complete deciduous Dentition Complete deciduous dentition The first Transitional Period The intertransitional period The 2nd Transitional period Permanent Dentition 2 www.indiandentalacademy.com
  3. 3.       Disorders of development of Dentition Development of Class II/1 Development of Class II div/2 Development of class III Development of Open bite Development of cross bite www.indiandentalacademy.com 3
  4. 4. Introduction to Occlusion    Oc = up Clusion = closing ; closing up Occlusion - Relationship of dental arches when tooth contacts are made. Ideal occlusion in broad functional term is –     Teeth alignment is such that masticatory loads are within physiological range and act through long axis of as many teeth in arch as possible. Lateral jaw movement without mechanical interference. When in rest position – freeway space is present Tooth alignment is aesthetically pleasing. www.indiandentalacademy.com 4
  5. 5. The Anatomical alignment of teeth  The Dental Arches –    Size and shape vary follow Catenary curve The Neutral Zone www.indiandentalacademy.com 5
  6. 6. The curvatures of teeth and arches    Curve of Spee. Curve of Wilson Curve of Monson www.indiandentalacademy.com 6
  7. 7. The anatomical occlusion of teeth Centric occlusion Arrangement of teeth in centric occ relation b/w teeth of both jaws B-L relation Centric contacts www.indiandentalacademy.com 7
  8. 8. Eccentric occlusion Tooth contacts in lateral and protrusive occlusal position www.indiandentalacademy.com 8
  9. 9. Andrew’s six keys of normal Occlusion 1. 2. 3. 4. 5. 6. Molar inter arch relationship Mesio- distal crown angulation Labio – lingual crown inclination Absence of rotation Tight contacts Curve of Spee. www.indiandentalacademy.com 9
  10. 10. Development of Concept of Occlusion www.indiandentalacademy.com 10
  11. 11. Development of Concepts of occlusion  It can be divided into    Fictional Period (prior to 1900) Hypothetical Period (1900 to 1930) Factual Period (1930 to present) www.indiandentalacademy.com 11
  12. 12. Fictional Period  Fuller Clark & Imrie talked of ‘antagonism’, ‘meeting’ or ‘gliding’ of teeth.  Talbot said it’s a historical event long since passed in the decline of species, and possible only with an atavism ‘throwback’ to our primitive ancestors.  The creation of a normal standard of occlusion , a basis on which to compare departure from normal was lacking. www.indiandentalacademy.com 12
  13. 13. Hypothetical Period  According to     Edward H. Angel Mathew Cryer and Calvin Case Lischer and Paul Simon Milo Hellman www.indiandentalacademy.com 13
  14. 14. Edward .H. Angle  In 1907 Angle put a hypothesis that: “Occlusion is the basis of the science of orthodontia. The shapes of the cusps, crowns and roots , and even the very structural material of the teeth and attachments are all designed for the purpose of making occlusion the one grand object…. we shall define occlusion as being normal relations of the occlusal inclined planes of the teeth when the jaws are closed.”     He described the illustration “Old glory”…. which according to him was ideal occlusion. Angle stated Apollo Belverdo’s straight profile as ideal The best eg. of his hypothesis was ‘key of Occlusion’ His hypothesis was suggestive of static occlusion www.indiandentalacademy.com 14
  15. 15. Apollo Belverdo Old Glory Skull www.indiandentalacademy.com 15
  16. 16. Mathew Cryer and Calvin case He opposed Angle    How could one mix prognathic denture and orthognathic profile? How bimaxillary protrusion considered normal and individual variation was not considered? Then they were proved right by Turner’s illustrations Normal occlusion ( it suits Apollo’s face better)  Case’s concept of www.indiandentalacademy.com occlusion was static 16
  17. 17. Wheeler’s illustrations for normal occlusion Prognathic Retrognathic www.indiandentalacademy.com 17
  18. 18. Lischer And Paul Simon    They tried to relate concept of occlusion by relating teeth with rest of the face and cranium. Lischer introduced mastication as requisite of occlusion Simon outlined the anthropometric approach Milo Hellman   He showed racial variation in normal occlusion His study was also confined to static occlusion www.indiandentalacademy.com 18
  19. 19. Factual Period     Dividing line b/w static and dynamic occlusion. 1931 Broadbent introduced Cephalometry. With this advanced study tech the factual period become functional period. By now 3 components of occlusion are set up  1. Interdigitation of teeth  2. Status of controlling musculature  3. TMJ integrity www.indiandentalacademy.com 19
  20. 20. Evolution of dentition www.indiandentalacademy.com 20
  21. 21. Evolution of Dentition  The mammalian dentition is 100, 000 million yrs old  The theories behind mammalian dentition are    Theory of Concrescence – derived by fusion of 2 or more primitive conical teeth. Theory of trituberculy – each tooth derived from single reptilian tooth by secondary differentiation of tubercule and root. Theory of multituberculy – derived from reduction and condensation of primitive multituberculate teeth. www.indiandentalacademy.com 21
  22. 22. Evolution of Dentition  Non mammalian vertebrates – Polyphyodonty (many dentitions)  In mammals –Diphyodonty (2 dentitions )  During growth of the animal – increase in the jaw size is associated with tooth size www.indiandentalacademy.com 22
  23. 23. Dentition of fishes ( Agnatha) Eg - Sea lamprey & hag fishes    No true calcified teeth Arranged circumferentially Horny teeth are also seen on the tongue www.indiandentalacademy.com 23
  24. 24. Chondrichthyes (carrtilagenous fishes)    Large no. of teeth are present Homodont & polyphyodont Teeth are covered by enameloid lower jaw of shark www.indiandentalacademy.com 24
  25. 25. Osteichthyes (bony fishes)     Haplodont – conical shape prehension Polyphyodont Teeth- vomer, palatine bones roof of the mouth & tongue www.indiandentalacademy.com 25
  26. 26. Amphibia    Small, homodont, polyphyodont prehension In the frog – small teeth on the upper jaw & no teeth on the lower jaw www.indiandentalacademy.com 26
  27. 27. Reptiles Homodont & polyphyodont  Tend to be tricuspid or cone shaped  Egg teeth – in embryos of lizards & snakes - used to break the shell  www.indiandentalacademy.com 27
  28. 28. Dentition of mammals    Heterodont ( 4 types ) Restricted to 2 rows Ability to masticate – improves digestive efficiency for high rate of metabolism www.indiandentalacademy.com 28
  29. 29. Other features       TMJ articulation Salivary glands Prismatic enamel Diphyodonty Secondary palate Significant muscle development www.indiandentalacademy.com 29
  30. 30. Dentition of protheria  Spiny ant eater – edentulous  Duck billed platypus – 3 functional posterior teeth in each jaw quadrant  No. of additional teeth develop but do not erupt but rapidly resorb www.indiandentalacademy.com 30
  31. 31. Metatheria (Marsupials)  Eg. Red Kangroo  Dental formula – 3/1, 0/0, 1/1, 4/4 . Feed on various plant. Anterior teeth allow the food to be firmly grasped. Marsupials have no. of dental features which distinguish them from placental animals.    www.indiandentalacademy.com 31
  32. 32. Eutheria Eg - hedge hog     Insectivoral Incisors form a forcep like mechanism to pick preys. Molars – primitive tritubercular with sharp cusps Suitable for crushing the shells of insects www.indiandentalacademy.com 32
  33. 33. Rodentia Eg - rat     Heterogenous , Monophyodont Continuously growing incisors DF 1/1, 0/0, 0/0, 3/3 Rat & mice are widely used as experimental animals in Dental sciences www.indiandentalacademy.com 33
  34. 34. Carnivora    Incisors are small and arranged in line. Enlarged canines – offensive weapons Incisors and canine – tearing flesh www.indiandentalacademy.com 34
  35. 35. Primates  Classified in to –    Prosimii or Lemur type Anthropoidea Mainly herbivorous sometimes insectivorous www.indiandentalacademy.com 35
  36. 36. Prosimii or Lemur type      DF – 2/2, 1/1, 3/3, 3/3 incisors & canines are procumbent and form dental comb. mid line diastema . Upper canine is blade like Upper molar tritubercular www.indiandentalacademy.com 36
  37. 37. Anthropoidea (monkey, apes & Man) Eg -Macaca monkey  DF – 2/2, 1/1, 2/2, 3/3  Canines are long & prominent ( esp. in male )  Lateral diastema  www.indiandentalacademy.com 37
  38. 38. Chimpanze  Resembles permanent teeth of man www.indiandentalacademy.com 38
  39. 39. Homosapiens  Modern man – existed 100,000 yrs. ago www.indiandentalacademy.com 39
  40. 40. Stages of Occlusal development www.indiandentalacademy.com 40
  41. 41. Stages of occlusal development from clinical view ( Barnett) www.indiandentalacademy.com 41
  42. 42. According to Vander Linden       Dev of Dentition from birth to Complete deciduous Dentition Complete deciduous dentition The 1st Transitional Period The intertransitional period Mixed Dentition The 2nd Transitional period Permanent Dentition www.indiandentalacademy.com 42
  43. 43. Prenatal Dental development www.indiandentalacademy.com 43
  44. 44. Prenatal Dental development  Prenatal beginning of the dentition      Initiation of odontogenesis bud stage cap stage bell stage Spatial patterns   Arch shape Spacing www.indiandentalacademy.com 44
  45. 45. Initiation of odontogenesis   3rd week of IUL - first sign of tooth dev. Epithelial thickening seen IL border of maxilla SL border of mandible  6 wk IUL Dental lamina is formed. www.indiandentalacademy.com 45
  46. 46. www.indiandentalacademy.com 46
  47. 47.  Morphologic changes - 6wks IUL till 4-5 yrs.  Occurs in 3 main phases   Initiation of entire deciduous dentition at 2nd month IUL Initiation of permanent teeth in successional lamina from 5th month IUL The dental lamina elongates distal to 2nd decid. Molar and give rise to permanent molar tooth germs www.indiandentalacademy.com 47
  48. 48. Bud Stage  Seen at 7th wk IUL  Increased mitotic activity at specific sites in DL produces 10 knob like tooth buds  Stage of proliferation with no morphodifferentiation of cells www.indiandentalacademy.com 48
  49. 49. Bud Stage Early bud stage Dental lamina Enamel organ Mesenchymal condensation Late bud stage www.indiandentalacademy.com 49
  50. 50. Cap Stage  At end of 8th wk concavity appears on deep surface of bud – cap shape  Epithelium enlarges and proliferates in to deeper ectomesenchyme  Its stage of morphodifferentiation www.indiandentalacademy.com 50
  51. 51. Cap Stage Early cap stage External dental epith. Dental follicle Inner enamel epith. Dental papilla Late cap stage Enamel cord Enamel knot Dental papilla www.indiandentalacademy.com 51
  52. 52. Bell stage  Enlargement of tooth germ and deepening of its undersurface  Germ looses connection with oral epith.  Stage of Histodifferentiation  Determine crown shape initate dentin and enamel formation www.indiandentalacademy.com 52
  53. 53. Bell stage Bell stage outer enamel epith. Stellate reticulum Dental follicle Stratum intermedium Inner enamel epithelium Dental papilla Advanced Bell stage Ameloblasts Enamel matrix Dentin Predentin Odontoblasts www.indiandentalacademy.com 53
  54. 54. Advanced Bell stage  Inner dental epithelium – Ameloblasts – Enamel  Outer dental epith. – dental cuticle  Transition zone b/w IDE & ODE – cervical loop  Neighboring cells of IDE in dental papilla – Dentinoblasts/odontoblasts – Dentin .  Hertwig’s rootsheath proliferate from CL which initiates radicular odontoblasts. www.indiandentalacademy.com 54
  55. 55. Arch Shape      At 6 to 8 weeks it’s A-P flattened. By bell stage or 4mth IUL – Catenary pattern. Cleft lip and palate arrest this development. Lateral shift of deciduous lat. incisor is seen. 4 diff arrangements of deciduous teeth in both jaws before birth www.indiandentalacademy.com 55
  56. 56. Graphic Reconstruction of prenatal Dental arch quadrant www.indiandentalacademy.com 56
  57. 57. Frontal sec through face of 24 wk fetus showing linear distance from midline to points on tooth germs www.indiandentalacademy.com 57
  58. 58. Spacing  Decid. anterior teeth appear crowded.  Lateral incisor is seen out of alignment before birth but usually erupt in good alignment. Summed crown size increases eight fold but summed interdental spacing shows little correlatin with it.  www.indiandentalacademy.com 58
  59. 59. The mouth of the Neonate www.indiandentalacademy.com 59
  60. 60. The mouth of the Neonate    The gum pads Neonatal jaw relationship Status of dentition www.indiandentalacademy.com 60
  61. 61. Gum Pads      At birth alveolar processes are covered by firm and pink gum pads Divided in to 10 segments by transverse grooves. Groove b/w canine and dm1 crypt – lateral sulcus – assessing relation of jaws. Maxillary arch is horse shoe shape and extend buccally and labially Mandibular arch is posterior to max. arch www.indiandentalacademy.com 61
  62. 62. Neonatal jaw relationship    Anterior openbite is seen. Contact mainly occur at dm1 region. Infantile open bite is normal as it helps in suckling. www.indiandentalacademy.com 62
  63. 63. The status of dentition   Neonates are without teeth for 6mths. Occasionally teeth seen in this period –      Natal Neonatal Pre-erupted These teeth are always mandibular incisors. Familial tendencies. www.indiandentalacademy.com 63
  64. 64. Tooth Eruption   Two types Preemergent eruption   Eruption before emergence of tooth in oral cavity. Two processes involved –    Resorption of the overlying bone (and primary tooth root). Eruption mechanism itself then move the tooth in cleared path. Failure of tooth eruption –   Failure of bone resorption (Cleidocranial dysplasia) Primary failure of eruption. www.indiandentalacademy.com 64
  65. 65.  Postemergent eruption  Eruption after emergence of tooth in oral cavity. Postemergent spurt  Rapid eruption from a time tooth penetrates the gingiva till tooth reaches occlusal level.  Eruption - During critical period b/w 8 PM to 1 AM.  After it attain occlusal contact ,occlusal forces opposes further eruption  www.indiandentalacademy.com 65
  66. 66.  Juvenile Occlusal equilibrium  Slow phase  Teeth erupt to fill the space created by vertical growth of mandibular ramus.  Adult occlusal equilibrium  Compensate for occlusal and proximal wear www.indiandentalacademy.com 66
  67. 67. Mechanism of tooth movement     Bone remodelling of crypt wall Root formation Vascular pressure Periodontal ligament traction www.indiandentalacademy.com 67
  68. 68. Development of the Dentition from Birth to complete Deciduous dentition www.indiandentalacademy.com 68
  69. 69. Development of the Dentition from Birth to complete Deciduous dentition     After birth jaws grow considerably for 6-8 mths. Lower jaw more dorsally placed irt upper. Ventral dev takes place during 1st yr – A-P relation Transverse dev –    median suture in maxilla Synchondrosis in mandible (till 6 mths.) Eruption sequence is A B D C E www.indiandentalacademy.com 69
  70. 70. Dev of dental arches and dev of deciduous teeth A. At birth B. Mand. Central incisor- 6 to 8 mths C. Max. central incisor 7-9 months D. U & L lateral incisors – 1 yr. www.indiandentalacademy.com 70
  71. 71. E. F. G. H. www.indiandentalacademy.com 1st molar – 16 mth. Canine – 20 mth. 2nd molar – b/w 24 & 30 mths. Complete deciduous dentition with successors within the jaws. 71
  72. 72. Displacement of U & L Dm1 to establish occlusion : Cone-funnel mechanism   www.indiandentalacademy.com Palatal cusp of max. 1st molar – cone Crater in mand. 1st molar –funnel 72
  73. 73. The Complete Deciduous Dentition ABCDE ABCDE www.indiandentalacademy.com 73
  74. 74. The Complete Deciduous Dentition  Competed at 2.5 yrs of age after dm2 erupts and lasts till 5 yr of age  Physiological spaces in primary dentition  Primate spaces Developmental spaces www.indiandentalacademy.com 74
  75. 75. Spacing in Deciduous dentition  Gap toothed smile - normal  Hollywood smile with teeth in contact - not normal www.indiandentalacademy.com 75
  76. 76. Occlusal relationship of U & L Dm2  3 types of terminal planes –  Flush terminal plane  Mesial step  distal step www.indiandentalacademy.com 76
  77. 77. Normal situation of the Deciduous dentition in occlusal, anterior and lateral view www.indiandentalacademy.com 77
  78. 78. The first Transition period www.indiandentalacademy.com 78
  79. 79. The First transition period  The emergence of 1st permanent molar A B C D E 6 ABCDE6  Transition of the incisors www.indiandentalacademy.com 79
  80. 80. The emergence of 1st permanent molar    1st teeth to emerge in permanent dentition. In mand. 6 –7 yr In maxillary arch 7- 8 yr The A-P relation b/w two opposing permanent molars depend upon –    Their previous position within the jaw Sagittal relation b/w maxilla and mandible Terminal planes of 2nd decid molars. www.indiandentalacademy.com 80
  81. 81. Influence of terminal plane on the position of 1st permanent molar www.indiandentalacademy.com 81
  82. 82. Exchange of Incisors   After eruption of Pm1 , primary incisors exchange with permanent incisors. Incisal Liability    7 mm in maxilla 5 mm in mandible The factors controlling the arrangement of permanent incisors are - www.indiandentalacademy.com 82
  83. 83.  Interdental spaces in deciduous dentition    Increase of inter-canine width     physiological & primate spaces are utilized If closed space – crowding occur Increases 3 mm in both jaws at time of eruption Increases1.5 mm when canine erupts So the clasps on canine attached as space maintainer should be cut off at this time Increase of anterior length  Increase in length of arch in A-P dimension www.indiandentalacademy.com 83
  84. 84.  Change of tooth axis of incisor     Permanent incisor erupt labially by 2 – 3 mm, attain overjet and over bite Pressure by tongue , lip and perioral musculature Interincisal angle  150 degree in decid. Incisors.  123 degree in perm. Incisor It increases arch circumference www.indiandentalacademy.com 84
  85. 85.  Ugly duckling stage  Child look unusual due to Too large permanent incisor compared to primary.  Flared incisors with midline diastema.  Transitional malocclusion – called ugly duckling stage - broadbent  www.indiandentalacademy.com 85
  86. 86. Sequence of normal transition of incisors At 5 yr. At 6 –7 yr. At 7 –8 yr. At 8 – 9 yr www.indiandentalacademy.com 86
  87. 87. Transition of incisors      Loss of decid. tooth is caused by Resorption of its root  By reduction of bone cervically Several week passes b/w shedding of decid and eruption of successor. In the interval reconstruction of alveolar process and healing of gingival defect occur A perm. teeth starts eruption after ¼ of its root formed Perm .teeth emerge in oral cavity when ¾ root is formed. www.indiandentalacademy.com 87
  88. 88. The inter transitional Period 12CDE6 12CDE6 www.indiandentalacademy.com 88
  89. 89. The inter transitional period       Consist of both decid. & perm. teeth Teeth present are 1 2 C D E 6 12CDE6 Ugly duckling stage persists in upper incisors. Under influence of tongue mand incisor attain proper sites from their lingual position. The decid teeth present are worn out at this stage. It is a stable phase with little changes in dentition. www.indiandentalacademy.com 89
  90. 90. The inter transitional period www.indiandentalacademy.com 90
  91. 91. The Second Transition Period www.indiandentalacademy.com 91
  92. 92. The Second transitional period   Transition of Lateral teeth Eruption of Second permanent molar www.indiandentalacademy.com 92
  93. 93. Transition of lateral teeth   Transition of C D E with 3 4 5 . For smooth exchange following are conditions–  Leeway space of Nance     Sum M-D width of 3, 4 & 5 < C D & E Space available is 22.3 – 21.5 = 0.8 (U) 23.5 – 21.1 = 2.4 (L) www.indiandentalacademy.com 93
  94. 94.  Order of exchange of lateral teeth    It takes 1 ½ yrs. to complete exchange of lateral teeth. Sequence of eruption is – 4 5 3 in maxillary and 3 4 5 in mand. www.indiandentalacademy.com 94
  95. 95. Eruption of second Permanent teeth   After exchange of lateral teeth 2nd permanent molar erupts. i.e after loss of all deciduous teeth. Sometimes it erupts before E sheds – leads to crowding www.indiandentalacademy.com 95
  96. 96. Transition of lateral teeth and eruption of 2nd perm molar At 9- 10 yrs At 10 – 11 yrs. At 10 – 12 yrs. At 11 – 12 yrs At 12 – 13 yrs. www.indiandentalacademy.com 96
  97. 97. The Permanent Dentition 1234567 1234567 www.indiandentalacademy.com 97
  98. 98. The Permanent Dentition  At around 13 yr of age all permanent teeth (except 3rd molar) are erupted. Situation in normal permanent dentition www.indiandentalacademy.com 98
  99. 99. Normal bucco-lingual inclination of perm teeth in both jaws www.indiandentalacademy.com 99
  100. 100. Disorders in development of Dentition www.indiandentalacademy.com 100
  101. 101. Disorders in development of Dentition  At time of eruption of Deciduous dentition –   Anomolies   Teething disorder - most of infants exhibit fever, diarrohea, vomiting , irritability etc before tooth eruption. Its rare for primary teeth to be congenitally missing. Primary tooth resorption   Hastened by inflammation and occlusal trauma Delayed by splinting and absence of successor www.indiandentalacademy.com 101
  102. 102.  Ankylosis of primary teeth   In Primary molars, esp during physiologic resorption Disorders of primary Occlusion –   Its less compared to permanent occlusion. Thumb sucking and other oral habits Posterior crossbite  Open bites  Class II malocclusion  Excessive overjet   Bruxism – functional malocclusion www.indiandentalacademy.com 102
  103. 103.  Factors affecting transition of teeth     Dental caries in primary teeth Disturbance in root resorption due to pulpal or periodontal disturbances A periapical lesion Premature loss of primary molar www.indiandentalacademy.com 103
  104. 104.  Anomolies in Permanent dentition      Microdontia, macrodontia Gemination ,Fusion, Dilaceration, Talon cusp, Dens evaginatus Supernumerary roots Dentinogenesis & Amelogenesis imperfecta Enamel Hypoplasia www.indiandentalacademy.com 104
  105. 105. Abnormalities in dental arch 1. 2. Arch Length Discrepancy 1. Crowding 2. Spacing Deviation in no. of teeth1. Absence of teeth ( Agenesis) 2. Supernumerary teeth www.indiandentalacademy.com 105
  106. 106. Absence of teeth ( Agenesis)  Sequece of agenesis is –  3rd molar > Mand. 2nd premolars > Max Lateral Incisors > Max. 2nd Premolar www.indiandentalacademy.com 106
  107. 107. Absence of teeth ( Agenesis) www.indiandentalacademy.com 107
  108. 108. Supernumerary teeth www.indiandentalacademy.com 108
  109. 109. Deviation in tooth size   Its relative in nature All teeth combined > or < relative to size of jaws or head.    Crowding Spacing Deviation in size of individual teeth  Tooth size Discrepancy www.indiandentalacademy.com 109
  110. 110. Tooth size Descrepancy www.indiandentalacademy.com 110
  111. 111. Deviation in individual teeth position www.indiandentalacademy.com 111
  112. 112. Ankylosis   Frequent in mand deciduous molars. In permanent 2 types   Due to abnormal position within jaw  Max perm. Canine Due to lack of space  Mand 3rd molar www.indiandentalacademy.com 112
  113. 113. Angle’s classification of Malocclusion   Class I ClassII  Class II div 1   Class II div 2   Class II div 1 subdivison Class II div 2 subdivison Class III www.indiandentalacademy.com 113
  114. 114. The Development of Occlusion in Class II/ 1 malocclusion www.indiandentalacademy.com 114
  115. 115. In Deciduous dentition Limited increase in overbite Mand dental arch dorsally placed irt maxillary Distal step www.indiandentalacademy.com 115
  116. 116. In Intertransitional period Increased overbite Mand dental arch dorsally placed, large overjet Mand 1st perm molar occludes dorsally to max www.indiandentalacademy.com 116
  117. 117. In Permanent Dentition Increased overbite Mand dental arch dorsally placed, large overjet Class II molar relation www.indiandentalacademy.com 117
  118. 118. The Development of Occlusion in Class II/2 malocclusion www.indiandentalacademy.com 118
  119. 119. Change in Incisor and Molar region in Class II /2 , from deciduous to permanent In Decid. Dentition Overjet less,high lip line Mand incisor erupt Normally Max erupting slightly upright Lower lip – lingual tipping of L. Incisor Lower lip – lingual tipping of U. Incisor In adult, U. C. Incisor tipped severly palatall Continued erution – till vertical contact www.indiandentalacademy.com 119
  120. 120. Class II /2 with more space in anterior segment Lingual tipping ( By L Lip) U C P incisor - Continous Arch with B & C U L P incisor Erupt in normal orientation as sufficient space available •Lingual tipping of U L P incisor by L lip. •Lingual tipping of lower incisors. •Rectangular arch form www.indiandentalacademy.com 120
  121. 121. Class II /2 with less space in anterior segment •Lingual tipping ( By L Lip) •U C P incisor - Continous Arch with B & C • Already limited space, reduced further by palatal tipping of centrals . • Lateral erupts labially • L lip placed lingual to laterals •Max. laterals rest on the L lip. •Max Central and Mand incisors are perpendicular to Occ plane www.indiandentalacademy.com 121
  122. 122. The Development of dentition in Class III www.indiandentalacademy.com 122
  123. 123. In Deciduous dentition Lower ant placed ventrally to max. less overbite Mand dental arch ventrally placed, reverse overjet Large mesial step www.indiandentalacademy.com 123
  124. 124. In Intertransitional period Incisal surface of U incisor contact ligual surface of lower Mand dental arch ventrally placed, reverse overjet Mand perm !st molar occludes too far mesially to max www.indiandentalacademy.com 124
  125. 125. In Permanent dentition Incisal surface of U incisor contact ligual surface of lower Mand dental arch ventrally placed, reverse overjet Mand perm !st molar occludes too far mesially to max www.indiandentalacademy.com 125
  126. 126. Development of Open bite www.indiandentalacademy.com 126
  127. 127. Anterior open bite Asymmetrical open bite due to thumb sucking in Deciduous dentition Open bite due to abnormal Tongue position (symmetrical) www.indiandentalacademy.com 127
  128. 128. Posterior open bite Open bite due to incomplete eruption of teeth.Resulting from interpositioning of tongue Open bite combined with inadequate contacts. www.indiandentalacademy.com 128
  129. 129. ClassII /1 Subdivison • • • Class I on right side, class II on left Overjet overbite too large Midline shift. www.indiandentalacademy.com 129
  130. 130. ClassIII Subdivison • • • Class I on right side, class III on left Anterior crossbite exists Midline shift. www.indiandentalacademy.com 130
  131. 131. Unilateral Crossbite Maxillary dental arch crosses the mandibular one distal to maxillary left canine www.indiandentalacademy.com 131
  132. 132. Bilateral Crossbite On both sides maxillary molars occlude with their buccal cusps instead of their palatal ones www.indiandentalacademy.com 132
  133. 133. Total exo-occlusion in ClassII/1   All maxillary teeth positioned exteriorly to mandibular Brodie Syndrome or Telescope bite www.indiandentalacademy.com 133
  134. 134. Total endo-occlusion in Class III All maxillary teeth positioned interiorly to mandibular ones www.indiandentalacademy.com 134
  135. 135. Refrences :          Oral Anatomy - Berkovitz Development of Dentition – Van der Linden Transition of human Dentition – PGM Vander Linden Handbook of orthodontics – Moyers Contemporary orthodontics –Proffit Orthhodontics - T. M. graber Oral histology – Tencate Dental Anatomy – Wheelers Dentistry for child – Mc Donald www.indiandentalacademy.com 135
  136. 136. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com 136

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