Development of occlusion

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Development of dentition and occlusion, final year BDS, Development of teeth

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Development of occlusion

  1. 1. Development ofDevelopment of OcclusionOcclusion
  2. 2. What is occlusion ?What is occlusion ?  The way maxillary and mandibular teeth articulateThe way maxillary and mandibular teeth articulate  Much more complexMuch more complex  Study of teeth , their morphologyStudy of teeth , their morphology  AngulationsAngulations  Muscles of masticationMuscles of mastication  TMJTMJ  Functional jaw movementsFunctional jaw movements  Relationship of teeth in centric occlusion centricRelationship of teeth in centric occlusion centric relation and in functionrelation and in function  Neuromuscular controlNeuromuscular control
  3. 3. Changes in occlusion with ageChanges in occlusion with age  From birth till adulthood and beyondFrom birth till adulthood and beyond occlusion undergoes significant changesocclusion undergoes significant changes  Sometimes drastic changes and sometimesSometimes drastic changes and sometimes more subtlemore subtle  Differentiate normal from abnormalDifferentiate normal from abnormal
  4. 4. Stages of dental developmentStages of dental development  Gum pad stageGum pad stage  From birth till eruption of first primary toothFrom birth till eruption of first primary tooth  Pink firm with dense layer of fibrous periosteumPink firm with dense layer of fibrous periosteum  Horse shoe shapedHorse shoe shaped  Show elevations and groovesShow elevations and grooves  Labiobuccal portion and lingual portionLabiobuccal portion and lingual portion  Dental grooveDental groove
  5. 5. Stages of dental developmentStages of dental development  Gum pad stageGum pad stage  Divided into ten segments by ten grooves, theDivided into ten segments by ten grooves, the transverse groovestransverse grooves  Transverse groove between canine and first deciduousTransverse groove between canine and first deciduous molar segment is lateral sulcusmolar segment is lateral sulcus  Anterior open bite relation ( infantile tongue thrust)Anterior open bite relation ( infantile tongue thrust)  Posterior segments touchingPosterior segments touching  Maxillary gum pads slightly overlaps mandibular gumMaxillary gum pads slightly overlaps mandibular gum pads horizontally and vertically i.e. complete overjetpads horizontally and vertically i.e. complete overjet
  6. 6. Primary dentition stagePrimary dentition stage  Extends from time of eruption of firstExtends from time of eruption of first primary teeth to time of eruption of firstprimary teeth to time of eruption of first permanent molar around 6 yrs of agepermanent molar around 6 yrs of age
  7. 7. Sequence of Calcification of PrimarySequence of Calcification of Primary TeethTeeth  Central incisorCentral incisor 14 weeks in utero14 weeks in utero  First molarFirst molar 15 weeks in utero15 weeks in utero  Lateral incisorLateral incisor 16 weeks in utero16 weeks in utero  CupidCupid 17 weeks in utero17 weeks in utero  Second molarSecond molar 18 weeks in utero18 weeks in utero
  8. 8. Sequence of Eruption of PrimarySequence of Eruption of Primary TeethTeeth  a - b - d - c - ea - b - d - c - e  Eruption faster in girlsEruption faster in girls  6 month variation = normal6 month variation = normal  no significant left/right differencesno significant left/right differences
  9. 9. Timing of Eruption of Primary TeethTiming of Eruption of Primary Teeth  MANDIBULARMANDIBULAR  Central incisorCentral incisor 661/2 month1/2 month  Lateral incisorLateral incisor 7 months7 months  CanineCanine 16-20 months16-20 months  First molarFirst molar 14-16 months14-16 months  Second molarSecond molar 20-30 months20-30 months
  10. 10. Timing of Eruption of Primary TeethTiming of Eruption of Primary Teeth  MAXILLARYMAXILLARY  Central incisorCentral incisor 771/2 month1/2 month  Lateral incisorLateral incisor 8 months8 months  CanineCanine 16-20 months16-20 months  First molarFirst molar 12-16 months12-16 months  Second molarSecond molar 20-30 months20-30 months
  11. 11. Primary dentition stagePrimary dentition stage  OverbiteOverbite  OverjetOverjet  SpacingSpacing  Molar relationshipsMolar relationships
  12. 12. Primary dentition stagePrimary dentition stage  OverbiteOverbite  Amount of vertical overlap between maxillaryAmount of vertical overlap between maxillary and mandibular central incisorsand mandibular central incisors  Described either in mm or as percentageDescribed either in mm or as percentage  Normally varies between 10-40%Normally varies between 10-40%  Edge to edge or zero overbiteEdge to edge or zero overbite  Lack of overlap ------------- open bite quantifiedLack of overlap ------------- open bite quantified in mmin mm  May be due to presence of oral habitsMay be due to presence of oral habits
  13. 13. Primary dentition stagePrimary dentition stage  OverjetOverjet  Amount of horizontal overlap betweenAmount of horizontal overlap between most protruded maxillary CI andmost protruded maxillary CI and corresponding mandibular central incisorscorresponding mandibular central incisors  Described in mmDescribed in mm  Normally varies between 0-4mmNormally varies between 0-4mm  Excessive overjet may be due to presenceExcessive overjet may be due to presence of oral habitsof oral habits
  14. 14. Spacing in deciduous dentitionSpacing in deciduous dentition  Generalized spacing (Baume’s space)Generalized spacing (Baume’s space)  Localized spacingLocalized spacing  No spacingNo spacing  CrowdingCrowding  Generalized spacing is a common occurrenceGeneralized spacing is a common occurrence  Tooth size arch length discrepancy in the formTooth size arch length discrepancy in the form of crowding less common ( 3% of individualsof crowding less common ( 3% of individuals with primary dentition )with primary dentition )
  15. 15. Spacing in deciduous dentitionSpacing in deciduous dentition  Localized spacing ( primate spaces )Localized spacing ( primate spaces )  Maxillary arch between lateral incisor and canineMaxillary arch between lateral incisor and canine  Mandibular arch between canine and first molarMandibular arch between canine and first molar  Also known as simian and anthropoid spacesAlso known as simian and anthropoid spaces  Helps in placement of canine cusps in oppositeHelps in placement of canine cusps in opposite archesarches
  16. 16. Occlusion of the Primary SecondOcclusion of the Primary Second MolarMolar  In primary dentition A-P molar relationship isIn primary dentition A-P molar relationship is described in terms of relationship betweendescribed in terms of relationship between terminal planesterminal planes  Look at the distal aspect of the 2nd molarLook at the distal aspect of the 2nd molar  Flush terminal plane – most commonFlush terminal plane – most common  Mesial stepMesial step  Distal stepDistal step
  17. 17. Flush Terminal PlaneFlush Terminal Plane  In the flush terminal plane both theIn the flush terminal plane both the maxillary and the mandibular planemaxillary and the mandibular plane are at the same level anterioare at the same level anterio posteriorlyposteriorly
  18. 18. Flush Terminal PlaneFlush Terminal Plane
  19. 19. Mesial stepMesial step  In the mesial step relationshipIn the mesial step relationship mandibular terminal plane is relativelymandibular terminal plane is relatively more mesial ( anteriorly) than themore mesial ( anteriorly) than the maxillary terminal planemaxillary terminal plane
  20. 20. Distal stepDistal step  In the distal step relationshipIn the distal step relationship mandibular terminal plane is relativelymandibular terminal plane is relatively more distal (posterior) than themore distal (posterior) than the maxillary terminal planemaxillary terminal plane
  21. 21. Distal stepDistal step
  22. 22. Distribution of terminal planeDistribution of terminal plane relationshipsrelationships  In one study involving 121 children atIn one study involving 121 children at age 5 yrs it was foundage 5 yrs it was found  Distal stepDistal step 10%10%  Flush terminal planeFlush terminal plane 29%29%  Mesial step 1mmMesial step 1mm 42%42%  Mesial step >1mmMesial step >1mm 19%19%
  23. 23. Importance of terminal planeImportance of terminal plane  Erupting first permanent molarsErupting first permanent molars are guided by distal surface ofare guided by distal surface of second primary molars as theysecond primary molars as they erupt into occlusionerupt into occlusion
  24. 24. Primary Cuspid OcclusionPrimary Cuspid Occlusion  Look at long axis of the maxillaryLook at long axis of the maxillary cuspidcuspid  Neutro cuspid (Class I)Neutro cuspid (Class I)  Disto cuspid (Class II)Disto cuspid (Class II)  Mesio cuspid (Class III)Mesio cuspid (Class III)
  25. 25.  Neutro cuspid (Class I)Neutro cuspid (Class I)
  26. 26.  Disto cuspid (Class II)Disto cuspid (Class II)
  27. 27.  Mesio cuspid (Class III)Mesio cuspid (Class III)
  28. 28. The Ideal Primary OcclusionThe Ideal Primary Occlusion  Ovoid archesOvoid arches  Good interdental or primaryGood interdental or primary spacingspacing  Flush terminal plane or mesial stepFlush terminal plane or mesial step molarsmolars  Neutro cuspidsNeutro cuspids
  29. 29. The Ideal Primary OcclusionThe Ideal Primary Occlusion  Deep biteDeep bite  Flat curve of speeFlat curve of spee  Shallow cuspal interdigitationShallow cuspal interdigitation  Incisors are more vertically placedIncisors are more vertically placed
  30. 30. Mixed DentitionMixed Dentition OcclusionOcclusion
  31. 31. Mixed dentition stageMixed dentition stage  Starts with the eruption of firstStarts with the eruption of first permanent toothpermanent tooth  Completed at the time last primaryCompleted at the time last primary tooth is shedtooth is shed  Significant changes in dentitionSignificant changes in dentition
  32. 32. Mixed dentition stageMixed dentition stage  Temporary open biteTemporary open bite  Antimere should erupt with in sixAntimere should erupt with in six monthsmonths  Sequence of eruption of permanentSequence of eruption of permanent teethteeth
  33. 33. Mixed dentition stageMixed dentition stage  During mixed dentition stage presenceDuring mixed dentition stage presence of midline diastema between centralof midline diastema between central incisors is a normal occurrenceincisors is a normal occurrence
  34. 34. Mixed dentition stageMixed dentition stage  Size may vary from 1mm-3mmSize may vary from 1mm-3mm  Usually closes by the time maxillaryUsually closes by the time maxillary canine fully eruptcanine fully erupt
  35. 35. Molar relatitionshipMolar relatitionship  Class IClass I  Class IIClass II  Class IIIClass III
  36. 36. Molar relationshipMolar relationship  Flush terminal plane may lead to:Flush terminal plane may lead to:  End to endEnd to end (end on)(end on)  Class I (Early or late mesial shift)Class I (Early or late mesial shift)  Class IIClass II  Mesial step may lead to:Mesial step may lead to:  Class I (normally)Class I (normally)  Class IIIClass III  Distal step leads to:Distal step leads to:  Class IIClass II
  37. 37. Class II Class I (desirable) ETE End to End Permanent Molar
  38. 38. Mesial Step Class III Class I (desirable) Mesial Step
  39. 39. Disto Step Class II Always Disto Step
  40. 40. Causes of changes in molarCauses of changes in molar relationshiprelationship  Early mesial shiftEarly mesial shift  Late mesial shiftLate mesial shift  Mandibular growthMandibular growth
  41. 41. Causes of changes in molarCauses of changes in molar relationshiprelationship  Early mesial shiftEarly mesial shift  Late mesial shiftLate mesial shift  Mandibular growthMandibular growth
  42. 42. Early mesial shiftEarly mesial shift  Occurs during early mixed dentitionOccurs during early mixed dentition  The eruptive forces of 1The eruptive forces of 1stst permanent molarpermanent molar push deciduous 1push deciduous 1stst and 2and 2ndnd molarsmolars  Occurs when primate spaces are presentOccurs when primate spaces are present
  43. 43. Leeway spaceLeeway space  Sum of (c-d-e) > (3-4-5) This allows moreSum of (c-d-e) > (3-4-5) This allows more space for 3-4-5 This "leeway space"space for 3-4-5 This "leeway space" averages 1.7 mm. in the mandibularaverages 1.7 mm. in the mandibular segment; 0.9 in the maxillary segmentsegment; 0.9 in the maxillary segment
  44. 44. Late mesial shiftLate mesial shift  Refers to mandibular permanent molarRefers to mandibular permanent molar moving mesiallymoving mesially  If permanent molars are ETE, late mesialIf permanent molars are ETE, late mesial shift allows mandibular molar to moveshift allows mandibular molar to move into a Class I occlusioninto a Class I occlusion
  45. 45. Late mesial shiftLate mesial shift FTP Class I Molar moves into this space...
  46. 46. Incisor LiabilityIncisor Liability  Permanent incisors are larger thanPermanent incisors are larger than primary incisorsprimary incisors  This difference in size is termedThis difference in size is termed "incisor liability""incisor liability"  How does the body create enoughHow does the body create enough room for the larger, permanentroom for the larger, permanent incisors?incisors?
  47. 47. Overcoming Incisor LiabilityOvercoming Incisor Liability  Interdental spacing of primary incisorsInterdental spacing of primary incisors  Intercanine arch width growthIntercanine arch width growth  Labial positioning of the permanentLabial positioning of the permanent incisorsincisors  Favorable size ratio between theFavorable size ratio between the primary and permanent incisorsprimary and permanent incisors
  48. 48. Overcoming Incisor LiabilityOvercoming Incisor Liability  Interdental spacing of primary incisorsInterdental spacing of primary incisors  Good interdental spacing of primary incisorsGood interdental spacing of primary incisors allows for better alignment of the largerallows for better alignment of the larger permanent incisors.permanent incisors.
  49. 49. Primary SpacingPrimary Spacing
  50. 50. Primary SpacingPrimary Spacing
  51. 51. Overcoming Incisor LiabilityOvercoming Incisor Liability  Intercanine arch width growthIntercanine arch width growth  Width growth creates more room for theWidth growth creates more room for the permanent incisorspermanent incisors  Mandibular intercanine growth occursMandibular intercanine growth occurs mostly during permanent incisor eruptionmostly during permanent incisor eruption  Maxillary intercanine growth occursMaxillary intercanine growth occurs during incisor eruptionduring incisor eruption  UnpredictableUnpredictable
  52. 52. Intercanine growthIntercanine growth
  53. 53. Overcoming Incisor LiabilityOvercoming Incisor Liability  Labial positioning of the permanentLabial positioning of the permanent incisorsincisors  Permanent incisors erupt to a morePermanent incisors erupt to a more labial positionlabial position  Permanent incisors are angled morePermanent incisors are angled more labiallylabially  The above creates more arch lengthThe above creates more arch length
  54. 54. Labial positioningLabial positioning
  55. 55. Overcoming Incisor LiabilityOvercoming Incisor Liability  Favorable size ratio between the primaryFavorable size ratio between the primary and permanent incisorsand permanent incisors  Size ratio between the primary andSize ratio between the primary and permanent incisors may be favorable orpermanent incisors may be favorable or unfavorableunfavorable  Favorable: large primary, small permanentFavorable: large primary, small permanent  Unfavorable: small primary, largeUnfavorable: small primary, large permanentpermanent
  56. 56. Mixed dentitionMixed dentition  First transitional periodFirst transitional period  Inter transitional periodInter transitional period  Second transitional periodSecond transitional period
  57. 57. Second transitional periodSecond transitional period  Characterized by replacement of deciduousCharacterized by replacement of deciduous molars and canines by premolars and permanentmolars and canines by premolars and permanent canines respectivelycanines respectively  Ugly duckling stageUgly duckling stage
  58. 58. Ugly duckling stageUgly duckling stage  Transient malocclusion seen in maxillary incisor regionTransient malocclusion seen in maxillary incisor region between 8-9 years of agebetween 8-9 years of age  Eruption of permanent caninesEruption of permanent canines  As canines erupt they put pressure on roots ofAs canines erupt they put pressure on roots of permanent lateral incisorspermanent lateral incisors  Pressure on permanent central incisorsPressure on permanent central incisors  Midline spacingMidline spacing  Described by Broadbent as ugly duckling stageDescribed by Broadbent as ugly duckling stage  Usually self correcting as the pressure is transferredUsually self correcting as the pressure is transferred from roots to crownsfrom roots to crowns
  59. 59. Predicting FuturePredicting Future Crowding –Crowding – Mixed dentition analysisMixed dentition analysis
  60. 60. Mixed Dentition AnalysisMixed Dentition Analysis  Why: predict amount of crowding afterWhy: predict amount of crowding after permanent teeth come inpermanent teeth come in  When: during mixed dentitionWhen: during mixed dentition  What: boley gauge, models, predictionWhat: boley gauge, models, prediction tabletable
  61. 61. MDA MethodologyMDA Methodology  Measure mesial-distal diameter of theMeasure mesial-distal diameter of the mandibular incisors and record the valuemandibular incisors and record the value  Determine the space required forDetermine the space required for alignment of incisorsalignment of incisors  Determine the amount of space availableDetermine the amount of space available for permanent canines and premolars afterfor permanent canines and premolars after incisor alignmentincisor alignment
  62. 62. MDA MethodologyMDA Methodology  Predict the combined width ofPredict the combined width of mandibular canines and premolarsmandibular canines and premolars with the aid of probability chartwith the aid of probability chart  This estimated canine and premolarThis estimated canine and premolar size value is subtracted from measuredsize value is subtracted from measured spacespace
  63. 63. Moyer's Prediction ChartMoyer's Prediction Chart 19.519.5 20.020.0 20.520.5 21.021.0 21.521.5 22.022.0 22.522.5 23.023.0 23.523.5 24.024.0 Max.Max. 75%75% 20.620.6 20.920.9 21.221.2 21.521.5 21.821.8 22.022.0 22.322.3 22.622.6 22.922.9 23.123.1 mandmand 75%75% 20.120.1 20.420.4 20.720.7 21.021.0 21.321.3 21.621.6 21.921.9 22.222.2 22.522.5 22.822.8
  64. 64. Allowance for Late Mesial ShiftAllowance for Late Mesial Shift  If permanent molars are end to end,If permanent molars are end to end, mandibular molar should move mesially tomandibular molar should move mesially to obtain Class I interdigitation.obtain Class I interdigitation.  This will decrease the arch length availableThis will decrease the arch length available for 3-4-5.for 3-4-5.  Reduce 1.7 mm. per side with ETEReduce 1.7 mm. per side with ETE relationship.relationship.
  65. 65. Johnson and Tanaka analysisJohnson and Tanaka analysis  Variation of moyer’s analysisVariation of moyer’s analysis  Table is not neededTable is not needed  Sum of widths of mandibular incisors is dividedSum of widths of mandibular incisors is divided by 2by 2  For the mandibular arch add add 10.5 to get theFor the mandibular arch add add 10.5 to get the resultresult  For the maxillary arch add 11.0 to get the resultFor the maxillary arch add 11.0 to get the result  Corresponds to 75% probability of moyers tableCorresponds to 75% probability of moyers table
  66. 66. Hixon and oldfather methodHixon and oldfather method  Maximum MD daimeter of CI and LI of oneMaximum MD daimeter of CI and LI of one side + MD Diameter of unerupted first andside + MD Diameter of unerupted first and second premolars on radigraphs taken bysecond premolars on radigraphs taken by paralleling technique.paralleling technique.  Use this sum to estimate size of 3+4+5 usingUse this sum to estimate size of 3+4+5 using the prediction chartthe prediction chart
  67. 67. Hixon and oldfather methodHixon and oldfather method Measured value Estimated tooth size 23 18.4 24 19.0 25 19.7 26 20.3 27 21.0 28 21.6 29 22.3 30 22.9
  68. 68. Radiographic methodRadiographic method  IOPA of the unerupted teeth and of overlyingIOPA of the unerupted teeth and of overlying primary teeth are takenprimary teeth are taken  The enlargement ratio for each uneruptedThe enlargement ratio for each unerupted permanent tooth is computed by measuring thepermanent tooth is computed by measuring the nearest erupted tooth in the mouth and then innearest erupted tooth in the mouth and then in the radiograph.the radiograph.
  69. 69. Radiographic methodRadiographic method Erupted tooth size in the mouth X unerupted tooth size in X ray Erupted tooth size in x ray = correct tooth size
  70. 70. Eruption and Occlusion of theEruption and Occlusion of the Permanent DentitionPermanent Dentition
  71. 71. Permanent dentition stagePermanent dentition stage  First molar calcification at birthFirst molar calcification at birth  Rest calcification after birthRest calcification after birth  Sequence of eruptionSequence of eruption  Timing of eruptionTiming of eruption  Permanent incisor erupt lingual and palatal toPermanent incisor erupt lingual and palatal to deciduous incisorsdeciduous incisors  Move labially as they eruptMove labially as they erupt  Premolars develop below the diverging roots of thePremolars develop below the diverging roots of the deciduous molarsdeciduous molars
  72. 72. Permanent dentition stagePermanent dentition stage  Overlap : in a normally occluding dentition, theOverlap : in a normally occluding dentition, the maxillary teeth are labial/buccal to mandibular teethmaxillary teeth are labial/buccal to mandibular teeth  Angulations : primary dentition teeth are verticallyAngulations : primary dentition teeth are vertically positioned, permanent dentition buccolingual andpositioned, permanent dentition buccolingual and mesiodistal angulationsmesiodistal angulations  Occlusion : with the exception of mandibular centralOcclusion : with the exception of mandibular central incisors and maxillary second molars, each permanentincisors and maxillary second molars, each permanent teeth occludes with two teeth from the opposite archteeth occludes with two teeth from the opposite arch  Overbite and overjet : 10-50% and 1-3 mm res.Overbite and overjet : 10-50% and 1-3 mm res.
  73. 73. Permanent dentition stagePermanent dentition stage  Posterior relationships :Posterior relationships :  Maxillary and mandibular molars are in class IMaxillary and mandibular molars are in class I relationshiprelationship  Posterior segment well interdigitatedPosterior segment well interdigitated  Maxillary canine should be occluding in the embrasureMaxillary canine should be occluding in the embrasure between the mandibular canine and first premolar.between the mandibular canine and first premolar.
  74. 74. Nolla's 10 Stages of CalcificationNolla's 10 Stages of Calcification  Stage 1 – absence of cryptStage 1 – absence of crypt  Stage 2 - initial calcificationStage 2 - initial calcification  Stage 3 - 1/3Stage 3 - 1/3rdrd of crown completedof crown completed  Stage 4 - 2/3Stage 4 - 2/3rdrd of crown completedof crown completed  Stage 5 - crown almost completedStage 5 - crown almost completed  Stage 6 - crown formation completeStage 6 - crown formation complete  stage 7 – 1/3stage 7 – 1/3rdrd of root completedof root completed  Stage 8 - alveolar crest pierced (2/3 root development)Stage 8 - alveolar crest pierced (2/3 root development)  Stage 9 - gingival margin pierced (3/4 root development)Stage 9 - gingival margin pierced (3/4 root development)  Stage 10 – apical end of root development completedStage 10 – apical end of root development completed  Interval between Stage 6 and full interdigitation is about 5 yearsInterval between Stage 6 and full interdigitation is about 5 years
  75. 75. SequenceSequence  Girls 5 months faster than boysGirls 5 months faster than boys  6-1-2-4-3-5-7 and 6-1-2-4-5-3-7 most6-1-2-4-3-5-7 and 6-1-2-4-5-3-7 most common in maxillacommon in maxilla  (6-1)-2-3-4-5-7 and (6-1)-2-4-3-5-7 most(6-1)-2-3-4-5-7 and (6-1)-2-4-3-5-7 most common in mandiblecommon in mandible
  76. 76. Sequence is Important!Sequence is Important!  Alteration of sequence of eruption alertsAlteration of sequence of eruption alerts the practitioner to potential problemsthe practitioner to potential problems  SupernumerarySupernumerary  Neoplasm or cystNeoplasm or cyst  ALWAYS COUNT THE TEETH!ALWAYS COUNT THE TEETH!
  77. 77. Calcification times (Max. and mand.Calcification times (Max. and mand. res.)res.)  Central incisorCentral incisor 3-4 m3-4 m 3-4 m3-4 m  Lateral incisorLateral incisor 10-12 m10-12 m 3-4 m3-4 m  CuspidCuspid 4-5 m4-5 m 4-5 m4-5 m  1st bicuspid1st bicuspid 1 1/2 y1 1/2 y 1 3/4 y1 3/4 y  2nd bicuspid2nd bicuspid 2 y2 y 2 1/4 y2 1/4 y  Second molarSecond molar 2 1/2 y2 1/2 y 2 3/4 y2 3/4 y
  78. 78. How To Remember ThisHow To Remember This  A group of teeth beginA group of teeth begin calcification every sixcalcification every six monthsmonths  Not exact, but closeNot exact, but close enoughenough BirthBirth 1st molars1st molars 6m6m Anterior teeth, exceptAnterior teeth, except maxillary lateralsmaxillary laterals 12m12m Maxillary lateralsMaxillary laterals 18m18m 1st bicuspids1st bicuspids 24m24m 2nd bicuspids2nd bicuspids 30m30m 2nd molars2nd molars
  79. 79. Average Times to RememberAverage Times to Remember  Hard tissue begins to enamel completedHard tissue begins to enamel completed 4-5 years4-5 years Except for 1st molar (3) and cuspid (6)Except for 1st molar (3) and cuspid (6)  Hard tissue begins to Root CompletionHard tissue begins to Root Completion 10 years, except for cuspids (13)10 years, except for cuspids (13)  Eruption to Root CompletionEruption to Root Completion 3 years3 years
  80. 80. Why Know Calcification Times?Why Know Calcification Times? Enamel hypoplasiaEnamel hypoplasia
  81. 81. FluorosisFluorosis
  82. 82. Mesial Drift and AnteriorMesial Drift and Anterior Component of ForceComponent of Force • Axial inclinationAxial inclination produces mesial forceproduces mesial force • Mesial driftMesial drift • Ectopic eruptionEctopic eruption • Space maintenanceSpace maintenance
  83. 83. Ectopic EruptionEctopic Eruption
  84. 84. Absence of Permanent TeethAbsence of Permanent Teeth  4-6% congenital absence4-6% congenital absence  Females more frequently missing teethFemales more frequently missing teeth  Most common congenitally absent teeth:Most common congenitally absent teeth:  mandibular 2nd premolarmandibular 2nd premolar  maxillary lateral incisormaxillary lateral incisor  maxillary 2nd premolarmaxillary 2nd premolar
  85. 85. Extra Permanent TeethExtra Permanent Teeth  Supernumerary teeth found mostSupernumerary teeth found most frequently in the maxillary incisor regionfrequently in the maxillary incisor region (mesiodens), and occasionally in the(mesiodens), and occasionally in the premolar areapremolar area  2-3% supernumerary teeth2-3% supernumerary teeth  Males more commonMales more common
  86. 86. Terms: Mixed DentitionTerms: Mixed Dentition  Classic mixed dentitionClassic mixed dentition 12cde612cde6  Early mixed dentitionEarly mixed dentition 1bcde61bcde6  Late mixed dentitionLate mixed dentition 1234e61234e6
  87. 87. Terms - Arch LengthTerms - Arch Length  Arch length is the distance inArch length is the distance in millimeters from the mesial of the 1stmillimeters from the mesial of the 1st permanent molar around the arch overpermanent molar around the arch over the contact points to the mesial of thethe contact points to the mesial of the 1st permanent molar on the opposite1st permanent molar on the opposite side.side.
  88. 88. Arch LengthArch Length
  89. 89. Terms - Overbite/OverjetTerms - Overbite/Overjet  OverbiteOverbite is a vertical measurement of theis a vertical measurement of the amount of overlap of the incisors.amount of overlap of the incisors.  OverjetOverjet is the millimeter horizontalis the millimeter horizontal measurement from the labial of the maxillarymeasurement from the labial of the maxillary central incisor to the labial of the mandibularcentral incisor to the labial of the mandibular central incisor.central incisor.
  90. 90. OverbiteOverbite
  91. 91. OverjetOverjet
  92. 92. Straight ProfileStraight Profile
  93. 93. Protrusive ProfileProtrusive Profile
  94. 94. Retrusive ProfileRetrusive Profile
  95. 95. Typical Child ProfileTypical Child Profile
  96. 96. Types of FacesTypes of Faces  Brachycephalic - broad & shortBrachycephalic - broad & short  Dolichocephalic - long & narrowDolichocephalic - long & narrow  Mesocephalic - normalMesocephalic - normal
  97. 97. Dimensional changes in theDimensional changes in the dental archesdental arches
  98. 98. Dimensional changes in theDimensional changes in the dental archesdental arches  The transition from primary dentition stage toThe transition from primary dentition stage to the permanent dentition stage has an impact onthe permanent dentition stage has an impact on dental arch length and intermolar anddental arch length and intermolar and intercanine widthintercanine width
  99. 99. Changes in the maxillary archChanges in the maxillary arch  The intercanine width increases by an average of 6.0 mm in aThe intercanine width increases by an average of 6.0 mm in a child between 3-13 years of agechild between 3-13 years of age  It continues to increase between 13-45 years of age by 1.7 mmIt continues to increase between 13-45 years of age by 1.7 mm  In primary dentition stage there is an increase of intermolarIn primary dentition stage there is an increase of intermolar width of 2.0 mm between 3-5 yearswidth of 2.0 mm between 3-5 years  The first permanent intermolar width increases by 2.2 mmThe first permanent intermolar width increases by 2.2 mm between 8-13 years of age and decreases by 1.0 mm by 45 yearsbetween 8-13 years of age and decreases by 1.0 mm by 45 years of ageof age  There is a slight decrease in arch length with age because ofThere is a slight decrease in arch length with age because of uprighting of incisorsuprighting of incisors ( Bishara S E : arch width changes from 6weeks to 45 years of age,( Bishara S E : arch width changes from 6weeks to 45 years of age, Am J of Orthod Dentofacial Ortop )Am J of Orthod Dentofacial Ortop )
  100. 100. Changes in the mandibular archChanges in the mandibular arch  The intercanine width increases by an average of 3.7 mm in aThe intercanine width increases by an average of 3.7 mm in a child between 3-13 years of agechild between 3-13 years of age  It decreases between 13-45 years of age by 1.2 mmIt decreases between 13-45 years of age by 1.2 mm  In primary dentition stage there is an increase of intermolarIn primary dentition stage there is an increase of intermolar width of 1.5 mm between 3-5 yearswidth of 1.5 mm between 3-5 years  The first permanent intermolar width increases by 1.0 mmThe first permanent intermolar width increases by 1.0 mm between 8-13 years of age and decreases by 1.0 mm by 45 yearsbetween 8-13 years of age and decreases by 1.0 mm by 45 years of ageof age  The arch length decreases in mixed and permanent dentitionThe arch length decreases in mixed and permanent dentition stages as a result of uprighting of incisors and the loss of leewaystages as a result of uprighting of incisors and the loss of leeway space by mesial movement of first permanent molarsspace by mesial movement of first permanent molars ( Bishara S E : arch width changes from 6weeks to 45 years of age,( Bishara S E : arch width changes from 6weeks to 45 years of age, Am J of Orthod Dentofacial Ortop )Am J of Orthod Dentofacial Ortop )

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