Occlusion

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Occlusion

  1. 1. 1 Development of Occlusion INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 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 www.indiandentalacademy.com
  3. 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
  4. 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
  5. 5. 5 The Anatomical alignment of teeth  The Dental Arches –  Size and shape vary  follow Catenary curve  The Neutral Zone www.indiandentalacademy.com
  6. 6. 6 The curvatures of teeth and arches  Curve of Spee.  Curve of Wilson  Curve of Monson www.indiandentalacademy.com
  7. 7. 7 The anatomical occlusion of teeth Centric occlusion B-L relation Centric contacts relation b/w teeth of both jaws Arrangement of teeth in centric occ www.indiandentalacademy.com
  8. 8. 8 Eccentric occlusion Tooth contacts in lateral and protrusive occlusal position www.indiandentalacademy.com
  9. 9. 9 Andrew’s six keys of normal Occlusion 1. Molar inter arch relationship 2. Mesio- distal crown angulation 3. Labio – lingual crown inclination 4. Absence of rotation 5. Tight contacts 6. Curve of Spee. www.indiandentalacademy.com
  10. 10. 10 Development of Concept of Occlusion www.indiandentalacademy.com
  11. 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
  12. 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
  13. 13. 13 Hypothetical Period  According to  Edward H. Angel  Mathew Cryer and Calvin Case  Lischer and Paul Simon  Milo Hellman www.indiandentalacademy.com
  14. 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
  15. 15. 15 Old Glory Skull Apollo Belverdo www.indiandentalacademy.com
  16. 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  Case’s concept of occlusion was static Normal occlusion ( it suits Apollo’s face better) www.indiandentalacademy.com
  17. 17. 17 Wheeler’s illustrations for normal occlusion PrognathicRetrognathic www.indiandentalacademy.com
  18. 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
  19. 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
  20. 20. 20 Evolution of dentition www.indiandentalacademy.com
  21. 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
  22. 22. 22  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 Evolution of Dentition www.indiandentalacademy.com
  23. 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
  24. 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
  25. 25. 25 Osteichthyes (bony fishes)  Haplodont – conical shape  prehension  Polyphyodont  Teeth- vomer, palatine bones roof of the mouth & tongue www.indiandentalacademy.com
  26. 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
  27. 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
  28. 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
  29. 29. 29 Other features  TMJ articulation  Salivary glands  Prismatic enamel  Diphyodonty  Secondary palate  Significant muscle development www.indiandentalacademy.com
  30. 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
  31. 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
  32. 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
  33. 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
  34. 34. 34 Carnivora  Incisors are small and arranged in line.  Enlarged canines – offensive weapons  Incisors and canine – tearing flesh www.indiandentalacademy.com
  35. 35. 35 Primates  Classified in to –  Prosimii or Lemur type  Anthropoidea  Mainly herbivorous sometimes insectivorous www.indiandentalacademy.com
  36. 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
  37. 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
  38. 38. 38 Chimpanze  Resembles permanent teeth of man www.indiandentalacademy.com
  39. 39. 39 Homosapiens  Modern man – existed 100,000 yrs. ago www.indiandentalacademy.com
  40. 40. 40 Stages of Occlusal development www.indiandentalacademy.com
  41. 41. 41 Stages of occlusal development from clinical view ( Barnett) www.indiandentalacademy.com
  42. 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
  43. 43. 43 Prenatal Dental development www.indiandentalacademy.com
  44. 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
  45. 45. 45 Initiation of odontogenesis  3rd week of IUL - first sign of tooth dev.  Epithelial thickening seen  6 wk IUL Dental lamina is formed. IL border of maxilla SL border of mandible www.indiandentalacademy.com
  46. 46. 46www.indiandentalacademy.com
  47. 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
  48. 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
  49. 49. 49 Bud Stage Early bud stage Late bud stage Dental lamina Enamel organ Mesenchymal condensation www.indiandentalacademy.com
  50. 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
  51. 51. 51 Cap Stage Early cap stage Late cap stage External dental epith. Dental follicle Inner enamel epith. Dental papilla Enamel cord Enamel knot Dental papilla www.indiandentalacademy.com
  52. 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
  53. 53. 53 Bell stage outer enamel epith. Stellate reticulum Dental follicle Stratum intermedium Inner enamel epithelium Dental papilla Ameloblasts Enamel matrix Dentin Predentin Odontoblasts Bell stage Advanced Bell stage www.indiandentalacademy.com
  54. 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
  55. 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
  56. 56. 56 Graphic Reconstruction of prenatal Dental arch quadrant www.indiandentalacademy.com
  57. 57. 57 Frontal sec through face of 24 wk fetus showing linear distance from midline to points on tooth germs www.indiandentalacademy.com
  58. 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
  59. 59. 59 The mouth of the Neonate www.indiandentalacademy.com
  60. 60. 60 The mouth of the Neonate  The gum pads  Neonatal jaw relationship  Status of dentition www.indiandentalacademy.com
  61. 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
  62. 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
  63. 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
  64. 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
  65. 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
  66. 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
  67. 67. 67 Mechanism of tooth movement  Bone remodelling of crypt wall  Root formation  Vascular pressure  Periodontal ligament traction www.indiandentalacademy.com
  68. 68. 68 Development of the Dentition from Birth to complete Deciduous dentition www.indiandentalacademy.com
  69. 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
  70. 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
  71. 71. 71 E. 1st molar – 16 mth. F. Canine – 20 mth. G. 2nd molar – b/w 24 & 30 mths. H. Complete deciduous dentition with successors within the jaws. www.indiandentalacademy.com
  72. 72. 72 Displacement of U & L Dm1 to establish occlusion : Cone-funnel mechanism  Palatal cusp of max. 1st molar – cone  Crater in mand. 1st molar –funnel www.indiandentalacademy.com
  73. 73. 73 The Complete Deciduous Dentition A B C D E A B C D E www.indiandentalacademy.com
  74. 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
  75. 75. 75 Spacing in Deciduous dentition  Gap toothed smile - normal  Hollywood smile with teeth in contact - not normal www.indiandentalacademy.com
  76. 76. 76 Occlusal relationship of U & L Dm2  3 types of terminal planes –  Flush terminal plane  Mesial step  distal step www.indiandentalacademy.com
  77. 77. 77 Normal situation of the Deciduous dentition in occlusal, anterior and lateral view www.indiandentalacademy.com
  78. 78. 78 The first Transition period www.indiandentalacademy.com
  79. 79. 79 The First transition period  The emergence of 1st permanent molar A B C D E 6 A B C D E 6  Transition of the incisors www.indiandentalacademy.com
  80. 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
  81. 81. 81 Influence of terminal plane on the position of 1st permanent molar www.indiandentalacademy.com
  82. 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
  83. 83. 83  Interdental spaces in deciduous dentition  physiological & primate spaces are utilized  If closed space – crowding occur  Increase of inter-canine width  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
  84. 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
  85. 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
  86. 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
  87. 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
  88. 88. 88 The inter transitional Period 1 2 C D E 6 1 2 C D E 6 www.indiandentalacademy.com
  89. 89. 89 The inter transitional period  Consist of both decid. & perm. teeth  Teeth present are 1 2 C D E 6 1 2 C D E 6  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
  90. 90. 90 The inter transitional period www.indiandentalacademy.com
  91. 91. 91 The Second Transition Period www.indiandentalacademy.com
  92. 92. 92 The Second transitional period  Transition of Lateral teeth  Eruption of Second permanent molar www.indiandentalacademy.com
  93. 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
  94. 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
  95. 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
  96. 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
  97. 97. 97 The Permanent Dentition 1 2 3 4 5 6 7 1 2 3 4 5 6 7 www.indiandentalacademy.com
  98. 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
  99. 99. 99 Normal bucco-lingual inclination of perm teeth in both jaws www.indiandentalacademy.com
  100. 100. 100 Disorders in development of Dentition www.indiandentalacademy.com
  101. 101. 101 Disorders in development of Dentition  At time of eruption of Deciduous dentition –  Teething disorder - most of infants exhibit fever, diarrohea, vomiting , irritability etc before tooth eruption.  Anomolies  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
  102. 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
  103. 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
  104. 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
  105. 105. 105 Abnormalities in dental arch 1. Arch Length Discrepancy 1. Crowding 2. Spacing 2. Deviation in no. of teeth- 1. Absence of teeth ( Agenesis) 2. Supernumerary teeth www.indiandentalacademy.com
  106. 106. 106 Absence of teeth ( Agenesis)  Sequece of agenesis is –  3rd molar > Mand. 2nd premolars > Max Lateral Incisors > Max. 2nd Premolar www.indiandentalacademy.com
  107. 107. 107 Absence of teeth ( Agenesis) www.indiandentalacademy.com
  108. 108. 108 Supernumerary teeth www.indiandentalacademy.com
  109. 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
  110. 110. 110 Tooth size Descrepancy www.indiandentalacademy.com
  111. 111. 111 Deviation in individual teeth position www.indiandentalacademy.com
  112. 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
  113. 113. 113 Angle’s classification of Malocclusion  Class I  ClassII  Class II div 1  Class II div 1 subdivison  Class II div 2  Class II div 2 subdivison  Class III www.indiandentalacademy.com
  114. 114. 114 The Development of Occlusion in Class II/ 1 malocclusion www.indiandentalacademy.com
  115. 115. 115 In Deciduous dentition Mand dental arch dorsally placed irt maxillary Limited increase in overbite Distal step www.indiandentalacademy.com
  116. 116. 116 In Intertransitional period Mand dental arch dorsally placed, large overjet Mand 1st perm molar occludes dorsally to max Increased overbite www.indiandentalacademy.com
  117. 117. 117 In Permanent Dentition Mand dental arch dorsally placed, large overjet Class II molar relation Increased overbite www.indiandentalacademy.com
  118. 118. 118 The Development of Occlusion in Class II/2 malocclusion www.indiandentalacademy.com
  119. 119. 119 Change in Incisor and Molar region in Class II /2 , from deciduous to permanent Mand incisor erupt Normally Max erupting slightly upright Lower lip – lingual tipping of U. Incisor In adult, U. C. Incisor tipped severly palatall Lower lip – lingual tipping of L. Incisor Continued erution – till vertical contact In Decid. Dentition Overjet less,high lip line www.indiandentalacademy.com
  120. 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
  121. 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
  122. 122. 122 The Development of dentition in Class III www.indiandentalacademy.com
  123. 123. 123 In Deciduous dentition Mand dental arch ventrally placed, reverse overjet Lower ant placed ventrally to max. less overbite Large mesial step www.indiandentalacademy.com
  124. 124. 124 In Intertransitional period Mand dental arch ventrally placed, reverse overjet Incisal surface of U incisor contact ligual surface of lower Mand perm !st molar occludes too far mesially to max www.indiandentalacademy.com
  125. 125. 125 In Permanent dentition Incisal surface of U incisor contact ligual surface of lower Mand perm !st molar occludes too far mesially to max Mand dental arch ventrally placed, reverse overjet www.indiandentalacademy.com
  126. 126. 126 Development of Open bite www.indiandentalacademy.com
  127. 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
  128. 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
  129. 129. 129 ClassII /1 Subdivison • Class I on right side, class II on left • Overjet overbite too large • Midline shift. www.indiandentalacademy.com
  130. 130. 130 ClassIII Subdivison • Class I on right side, class III on left • Anterior crossbite exists • Midline shift. www.indiandentalacademy.com
  131. 131. 131 Unilateral Crossbite Maxillary dental arch crosses the mandibular one distal to maxillary left canine www.indiandentalacademy.com
  132. 132. 132 Bilateral Crossbite On both sides maxillary molars occlude with their buccal cusps instead of their palatal ones www.indiandentalacademy.com
  133. 133. 133 Total exo-occlusion in ClassII/1  All maxillary teeth positioned exteriorly to mandibular  Brodie Syndrome or Telescope bite www.indiandentalacademy.com
  134. 134. 134 Total endo-occlusion in Class III All maxillary teeth positioned interiorly to mandibular ones www.indiandentalacademy.com
  135. 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
  136. 136. Thank you For more details please visit www.indiandentalacademy.com 136www.indiandentalacademy.com

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