Development of occlusion

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

1. Development of Development of
Occlusion Occlusion

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 centric Relationship of teeth in centric occlusion centric
relation and in functionrelation and in function
Neuromuscular controlNeuromuscular control

3. Changes in occlusion with ageChanges in occlusion with age
From birth till adulthood and beyond From birth till adulthood and beyond
occlusion undergoes significant changesocclusion undergoes significant changes
Sometimes drastic changes and sometimes Sometimes drastic changes and sometimes
more subtlemore subtle
Differentiate normal from abnormalDifferentiate normal from abnormal

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. Stages of dental developmentStages of dental development
Gum pad stageGum pad stage
Divided into ten segments by ten grooves, the Divided into ten segments by ten grooves, the
transverse groovestransverse grooves
Transverse groove between canine and first deciduous Transverse 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 gum Maxillary gum pads slightly overlaps mandibular gum
pads horizontally and vertically i.e. complete overjetpads horizontally and vertically i.e. complete overjet

6. Primary dentition stagePrimary dentition stage
Extends from time of eruption of first Extends from time of eruption of first
primary teeth to time of eruption of first primary teeth to time of eruption of first
permanent molar around 6 yrs of agepermanent molar around 6 yrs of age

7. Sequence of Calcification of Primary Sequence of Calcification of Primary
Teeth Teeth
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. Sequence of Eruption of Primary Sequence of Eruption of Primary
Teeth Teeth
a - b - d - c - e a - b - d - c - e
Eruption faster in girls Eruption faster in girls
6 month variation = normal 6 month variation = normal
no significant left/right differencesno significant left/right differences

9. Timing of Eruption of Primary Teeth Timing of Eruption of Primary Teeth
MANDIBULARMANDIBULAR
Central incisorCentral incisor661/2 month1/2 month
Lateral incisorLateral incisor7 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. Timing of Eruption of Primary Teeth Timing of Eruption of Primary Teeth
MAXILLARYMAXILLARY
Central incisorCentral incisor771/2 month1/2 month
Lateral incisorLateral incisor8 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. Primary dentition stagePrimary dentition stage
Overbite Overbite
OverjetOverjet
SpacingSpacing
Molar relationshipsMolar relationships

12. Primary dentition stagePrimary dentition stage
Overbite Overbite
Amount of vertical overlap between maxillary Amount 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 quantified Lack of overlap ------------- open bite quantified
in mmin mm
May be due to presence of oral habitsMay be due to presence of oral habits

13. Primary dentition stagePrimary dentition stage
Overjet Overjet
Amount of horizontal overlap between Amount of horizontal overlap between
most protruded maxillary CI and most 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 presence Excessive overjet may be due to presence
of oral habitsof oral habits

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 form Tooth size arch length discrepancy in the form
of crowding less common ( 3% of individuals of crowding less common ( 3% of individuals
with primary dentition )with primary dentition )

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 opposite Helps in placement of canine cusps in opposite
archesarches

16. Occlusion of the Primary Second Occlusion of the Primary Second
Molar Molar
In primary dentition A-P molar relationship is In primary dentition A-P molar relationship is
described in terms of relationship between described 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 common Flush terminal plane – most common
Mesial step Mesial step
Distal step Distal step

17. Flush Terminal Plane Flush Terminal Plane
In the flush terminal plane both the In the flush terminal plane both the
maxillary and the mandibular plane maxillary and the mandibular plane
are at the same level anterio are at the same level anterio
posteriorlyposteriorly

18. Flush Terminal Plane Flush Terminal Plane

19. Mesial step Mesial step
In the mesial step relationship In the mesial step relationship
mandibular terminal plane is relatively mandibular terminal plane is relatively
more mesial ( anteriorly) than the more mesial ( anteriorly) than the
maxillary terminal planemaxillary terminal plane

20. Distal step Distal step
In the distal step relationship In the distal step relationship
mandibular terminal plane is relatively mandibular terminal plane is relatively
more distal (posterior) than the more distal (posterior) than the
maxillary terminal planemaxillary terminal plane

21. Distal step Distal step

22. Distribution of terminal plane Distribution of terminal plane
relationships relationships
In one study involving 121 children at In 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 plane29%29%
Mesial step 1mmMesial step 1mm 42%42%
Mesial step >1mmMesial step >1mm 19%19%

23. Importance of terminal plane Importance of terminal plane
Erupting first permanent molars Erupting first permanent molars
are guided by distal surface of are guided by distal surface of
second primary molars as they second primary molars as they
erupt into occlusionerupt into occlusion

24. Primary Cuspid Occlusion Primary Cuspid Occlusion
Look at long axis of the maxillary Look at long axis of the maxillary
cuspid cuspid
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. Neutro cuspid (Class I)Neutro cuspid (Class I)

26. Disto cuspid (Class II)Disto cuspid (Class II)

27. Mesio cuspid (Class III)Mesio cuspid (Class III)

28. The Ideal Primary Occlusion The Ideal Primary Occlusion
Ovoid arches Ovoid arches
Good interdental or primary Good interdental or primary
spacing spacing
Flush terminal plane or mesial step Flush terminal plane or mesial step
molarsmolars
Neutro cuspidsNeutro cuspids

29. The Ideal Primary Occlusion The 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. Mixed Dentition Mixed Dentition
Occlusion Occlusion

31. Mixed dentition stage Mixed dentition stage
Starts with the eruption of first Starts with the eruption of first
permanent toothpermanent tooth
Completed at the time last primary Completed at the time last primary
tooth is shedtooth is shed
Significant changes in dentitionSignificant changes in dentition

32. Mixed dentition stage Mixed dentition stage
Temporary open biteTemporary open bite
Antimere should erupt with in six Antimere should erupt with in six
monthsmonths
Sequence of eruption of permanent Sequence of eruption of permanent
teeth teeth

33. Mixed dentition stage Mixed dentition stage
During mixed dentition stage presence During mixed dentition stage presence
of midline diastema between central of midline diastema between central
incisors is a normal occurrenceincisors is a normal occurrence

34. Mixed dentition stage Mixed dentition stage
Size may vary from 1mm-3mmSize may vary from 1mm-3mm
Usually closes by the time maxillary Usually closes by the time maxillary
canine fully eruptcanine fully erupt

35. Molar relatitionship Molar relatitionship
Class IClass I
Class IIClass II
Class IIIClass III

36. Molar relationship Molar 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 III Class III
Distal step leads to:Distal step leads to:
 Class IIClass II

37. Class II
Class I
(desirable)
ETE
End to End Permanent Molar

38. Mesial
Step
Class III
Class I
(desirable)
Mesial Step

39. Disto
Step
Class II
Always
Disto Step

40. Causes of changes in molar Causes of changes in molar
relationship relationship
Early mesial shift Early mesial shift
Late mesial shift Late mesial shift
Mandibular growthMandibular growth

41. Causes of changes in molar Causes of changes in molar
relationship relationship
Early mesial shift Early mesial shift
Late mesial shift Late mesial shift
Mandibular growthMandibular growth

42. Early mesial shiftEarly mesial shift
Occurs during early mixed dentitionOccurs during early mixed dentition
The eruptive forces of 1The eruptive forces of 1
stst
permanent molar permanent molar
push deciduous 1push deciduous 1
stst
and 2 and 2
ndnd
molars molars
Occurs when primate spaces are presentOccurs when primate spaces are present

43. Leeway spaceLeeway space
Sum of (c-d-e) > (3-4-5) This allows more Sum 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 mandibular averages 1.7 mm. in the mandibular
segment; 0.9 in the maxillary segment segment; 0.9 in the maxillary segment

45. Late mesial shiftLate mesial shift
Refers to mandibular permanent molar Refers to mandibular permanent molar
moving mesially moving mesially
If permanent molars are ETE, late mesial If permanent molars are ETE, late mesial
shift allows mandibular molar to move shift allows mandibular molar to move
into a Class I occlusion into a Class I occlusion

46. Late mesial shiftLate mesial shift
FTP Class I
Molar moves into
this space...

47. Incisor Liability Incisor Liability
Permanent incisors are larger than Permanent incisors are larger than
primary incisors primary incisors
This difference in size is termed This difference in size is termed
"incisor liability" "incisor liability"
How does the body create enough How does the body create enough
room for the larger, permanent room for the larger, permanent
incisors? incisors?

48. Overcoming Incisor Liability Overcoming Incisor Liability
Interdental spacing of primary incisors Interdental spacing of primary incisors
Intercanine arch width growth Intercanine arch width growth
Labial positioning of the permanent Labial positioning of the permanent
incisorsincisors
Favorable size ratio between the Favorable size ratio between the
primary and permanent incisorsprimary and permanent incisors

49. Overcoming Incisor Liability Overcoming Incisor Liability
Interdental spacing of primary incisorsInterdental spacing of primary incisors
Good interdental spacing of primary incisors Good interdental spacing of primary incisors
allows for better alignment of the larger allows for better alignment of the larger
permanent incisors.permanent incisors.

50. Primary Spacing Primary Spacing

51. Primary Spacing Primary Spacing

52. Overcoming Incisor Liability Overcoming Incisor Liability
Intercanine arch width growth Intercanine arch width growth
Width growth creates more room for the Width growth creates more room for the
permanent incisors permanent incisors
Mandibular intercanine growth occurs Mandibular intercanine growth occurs
mostly during permanent incisor eruption mostly during permanent incisor eruption
Maxillary intercanine growth occurs Maxillary intercanine growth occurs
during incisor eruptionduring incisor eruption
UnpredictableUnpredictable

53. Intercanine growth Intercanine growth

54. Overcoming Incisor Liability Overcoming Incisor Liability
Labial positioning of the permanent Labial positioning of the permanent
incisors incisors
Permanent incisors erupt to a more Permanent incisors erupt to a more
labial position labial position
Permanent incisors are angled more Permanent incisors are angled more
labially labially
The above creates more arch lengthThe above creates more arch length

55. Labial positioning Labial positioning

56. Overcoming Incisor Liability Overcoming Incisor Liability
Favorable size ratio between the primary Favorable size ratio between the primary
and permanent incisors and permanent incisors
Size ratio between the primary and Size ratio between the primary and
permanent incisors may be favorable or permanent incisors may be favorable or
unfavorable unfavorable
Favorable: large primary, small permanent Favorable: large primary, small permanent
Unfavorable: small primary, large Unfavorable: small primary, large
permanentpermanent

60. Mixed dentitionMixed dentition
First transitional periodFirst transitional period
Inter transitional periodInter transitional period
Second transitional periodSecond transitional period

61. Second transitional periodSecond transitional period
Characterized by replacement of deciduous Characterized by replacement of deciduous
molars and canines by premolars and permanent molars and canines by premolars and permanent
canines respectivelycanines respectively
Ugly duckling stageUgly duckling stage

62. Ugly duckling stageUgly duckling stage
Transient malocclusion seen in maxillary incisor region Transient 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 of As 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 transferred Usually self correcting as the pressure is transferred
from roots to crownsfrom roots to crowns

63. Predicting Future Predicting Future
Crowding – Crowding –
Mixed dentition analysis Mixed dentition analysis

64. Mixed Dentition Analysis Mixed Dentition Analysis
Why: predict amount of crowding after Why: predict amount of crowding after
permanent teeth come inpermanent teeth come in
 When: during mixed dentition When: during mixed dentition
What: boley gauge, models, prediction What: boley gauge, models, prediction
tabletable

65. MDA Methodology MDA Methodology
Measure mesial-distal diameter of the Measure mesial-distal diameter of the
mandibular incisors and record the valuemandibular incisors and record the value
Determine the space required for Determine the space required for
alignment of incisors alignment of incisors
Determine the amount of space available Determine the amount of space available
for permanent canines and premolars after for permanent canines and premolars after
incisor alignmentincisor alignment

66. MDA Methodology MDA Methodology
Predict the combined width of Predict the combined width of
mandibular canines and premolars mandibular canines and premolars
with the aid of probability chartwith the aid of probability chart
This estimated canine and premolar This estimated canine and premolar
size value is subtracted from measured size value is subtracted from measured
spacespace

67. Moyer's Prediction Chart Moyer's Prediction Chart
19.519.520.020.020.520.521.021.021.521.522.022.022.522.523.023.023.523.524.024.0
Max. Max.
75%75%
20.620.620.920.921.221.221.521.521.821.822.022.022.322.322.622.622.922.923.123.1
mandmand
75%75%
20.120.120.420.420.720.721.021.021.321.321.621.621.921.922.222.222.522.522.822.8

68. Allowance for Late Mesial Shift Allowance for Late Mesial Shift
If permanent molars are end to end, If permanent molars are end to end,
mandibular molar should move mesially to mandibular molar should move mesially to
obtain Class I interdigitation.obtain Class I interdigitation.
 This will decrease the arch length available This will decrease the arch length available
for 3-4-5.for 3-4-5.
 Reduce 1.7 mm. per side with ETE Reduce 1.7 mm. per side with ETE
relationship. relationship.

69. 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 divided Sum of widths of mandibular incisors is divided
by 2by 2
For the mandibular arch add add 10.5 to get the For the mandibular arch add add 10.5 to get the
resultresult
For the maxillary arch add 11.0 to get the result For the maxillary arch add 11.0 to get the result
Corresponds to 75% probability of moyers tableCorresponds to 75% probability of moyers table

70. Hixon and oldfather methodHixon and oldfather method
Maximum MD daimeter of CI and LI of one Maximum MD daimeter of CI and LI of one
side + MD Diameter of unerupted first and side + MD Diameter of unerupted first and
second premolars on radigraphs taken by second premolars on radigraphs taken by
paralleling technique.paralleling technique.
Use this sum to estimate size of 3+4+5 using Use this sum to estimate size of 3+4+5 using
the prediction chart the prediction chart

71. 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

72. Radiographic methodRadiographic method
IOPA of the unerupted teeth and of overlying IOPA of the unerupted teeth and of overlying
primary teeth are takenprimary teeth are taken
The enlargement ratio for each unerupted The enlargement ratio for each unerupted
permanent tooth is computed by measuring the permanent tooth is computed by measuring the
nearest erupted tooth in the mouth and then in nearest erupted tooth in the mouth and then in
the radiograph.the radiograph.

73. 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

74. Eruption and Occlusion of the Eruption and Occlusion of the
Permanent Dentition Permanent Dentition

75. 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 to Permanent incisor erupt lingual and palatal to
deciduous incisors deciduous incisors
Move labially as they eruptMove labially as they erupt
Premolars develop below the diverging roots of the Premolars develop below the diverging roots of the
deciduous molarsdeciduous molars

76. Permanent dentition stagePermanent dentition stage
Overlap : in a normally occluding dentition, the Overlap : 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 vertically Angulations : primary dentition teeth are vertically
positioned, permanent dentition buccolingual and positioned, permanent dentition buccolingual and
mesiodistal angulationsmesiodistal angulations
Occlusion : with the exception of mandibular central Occlusion : with the exception of mandibular central
incisors and maxillary second molars, each permanent incisors 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.

77. Permanent dentition stagePermanent dentition stage
Posterior relationships : Posterior relationships :
Maxillary and mandibular molars are in class I Maxillary and mandibular molars are in class I
relationshiprelationship
Posterior segment well interdigitatedPosterior segment well interdigitated
Maxillary canine should be occluding in the embrasure Maxillary canine should be occluding in the embrasure
between the mandibular canine and first premolar.between the mandibular canine and first premolar.

78. Nolla's 10 Stages of Calcification Nolla'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 - 1/3
rdrd
of crown completed of crown completed
Stage 4 - 2/3Stage 4 - 2/3
rdrd
of crown completed of 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 – 1/3
rdrd
of root completed of 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 years Interval between Stage 6 and full interdigitation is about 5 years

79. Sequence Sequence
Girls 5 months faster than boys Girls 5 months faster than boys
6-1-2-4-3-5-7 and 6-1-2-4-5-3-7 most 6-1-2-4-3-5-7 and 6-1-2-4-5-3-7 most
common in maxilla common 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

80. Sequence is Important! Sequence is Important!
Alteration of sequence of eruption alerts Alteration of sequence of eruption alerts
the practitioner to potential problems the practitioner to potential problems
Supernumerary Supernumerary
Neoplasm or cyst Neoplasm or cyst
ALWAYS COUNT THE TEETH!ALWAYS COUNT THE TEETH!

81. Calcification times (Max. and mand. Calcification times (Max. and mand.
res.)res.)
Central incisorCentral incisor3-4 m3-4 m 3-4 m 3-4 m
Lateral incisorLateral incisor10-12 m10-12 m3-4 m 3-4 m
CuspidCuspid 4-5 m4-5 m 4-5 m 4-5 m
1st bicuspid1st bicuspid 1 1/2 y1 1/2 y1 3/4 y 1 3/4 y
2nd bicuspid2nd bicuspid 2 y2 y 2 1/4 y 2 1/4 y
Second molarSecond molar 2 1/2 y2 1/2 y2 3/4 y 2 3/4 y

82. How To Remember This How To Remember This
A group of teeth begin A group of teeth begin
calcification every six calcification every six
months months
Not exact, but close Not exact, but close
enough enough
Birth Birth 1st molars 1st molars
6m6m Anterior teeth, except Anterior teeth, except
maxillary laterals maxillary laterals
12m12mMaxillary laterals Maxillary laterals
18m18m1st bicuspids 1st bicuspids
24m24m2nd bicuspids 2nd bicuspids
30m30m2nd molars 2nd molars

83. Average Times to Remember Average Times to Remember
Hard tissue begins to enamel completed Hard tissue begins to enamel completed
4-5 years 4-5 years
Except for 1st molar (3) and cuspid (6)Except for 1st molar (3) and cuspid (6)
Hard tissue begins to Root Completion Hard tissue begins to Root Completion
10 years, except for cuspids (13)10 years, except for cuspids (13)
Eruption to Root Completion Eruption to Root Completion
3 years3 years

84. Why Know Calcification Times? Why Know Calcification Times?
Enamel hypoplasiaEnamel hypoplasia

85. Fluorosis Fluorosis

86. 
Mesial Drift and Anterior Mesial Drift and Anterior
Component of ForceComponent of Force
•Axial inclination Axial inclination
produces mesial force produces mesial force
•Mesial drift Mesial drift
•Ectopic eruption Ectopic eruption
•Space maintenanceSpace maintenance

87. Ectopic EruptionEctopic Eruption

88. Absence of Permanent Teeth Absence of Permanent Teeth
4-6% congenital absence 4-6% congenital absence
Females more frequently missing teeth Females more frequently missing teeth
Most common congenitally absent teeth: Most common congenitally absent teeth:
mandibular 2nd premolar mandibular 2nd premolar
maxillary lateral incisor maxillary lateral incisor
maxillary 2nd premolarmaxillary 2nd premolar

89. Extra Permanent Teeth Extra Permanent Teeth
Supernumerary teeth found most Supernumerary teeth found most
frequently in the maxillary incisor region frequently in the maxillary incisor region
(mesiodens), and occasionally in the (mesiodens), and occasionally in the
premolar area premolar area
2-3% supernumerary teeth2-3% supernumerary teeth
Males more common Males more common

90. Terms: Mixed Dentition Terms: Mixed Dentition
Classic mixed dentitionClassic mixed dentition
12cde6 12cde6
Early mixed dentition Early mixed dentition
1bcde6 1bcde6
Late mixed dentitionLate mixed dentition
1234e61234e6

91. Terms - Arch Length Terms - Arch Length
Arch length is the distance in Arch length is the distance in
millimeters from the mesial of the 1st millimeters from the mesial of the 1st
permanent molar around the arch over permanent molar around the arch over
the contact points to the mesial of the the contact points to the mesial of the
1st permanent molar on the opposite 1st permanent molar on the opposite
side.side.

92. Arch LengthArch Length

93. Terms - Overbite/Overjet Terms - Overbite/Overjet
OverbiteOverbite is a vertical measurement of the is a vertical measurement of the
amount of overlap of the incisors. amount of overlap of the incisors.
OverjetOverjet is the millimeter horizontal is the millimeter horizontal
measurement from the labial of the maxillary measurement from the labial of the maxillary
central incisor to the labial of the mandibular central incisor to the labial of the mandibular
central incisor. central incisor.

94. OverbiteOverbite

95. OverjetOverjet

96. Straight ProfileStraight Profile

97. Protrusive ProfileProtrusive Profile

98. Retrusive ProfileRetrusive Profile

99. Typical Child Profile Typical Child Profile

100. Types of Faces Types of Faces
Brachycephalic - broad & short Brachycephalic - broad & short
Dolichocephalic - long & narrow Dolichocephalic - long & narrow
Mesocephalic - normalMesocephalic - normal

101. Dimensional changes in the Dimensional changes in the
dental archesdental arches

102. Dimensional changes in the Dimensional changes in the
dental archesdental arches
The transition from primary dentition stage to The transition from primary dentition stage to
the permanent dentition stage has an impact on the permanent dentition stage has an impact on
dental arch length and intermolar and dental arch length and intermolar and
intercanine width intercanine width

103. Changes in the maxillary archChanges in the maxillary arch
The intercanine width increases by an average of 6.0 mm in a The 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 intermolar In primary dentition stage there is an increase of intermolar
width of 2.0 mm between 3-5 years width of 2.0 mm between 3-5 years
The first permanent intermolar width increases by 2.2 mm The first permanent intermolar width increases by 2.2 mm
between 8-13 years of age and decreases by 1.0 mm by 45 years between 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 of There 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 )

104. Changes in the mandibular archChanges in the mandibular arch
The intercanine width increases by an average of 3.7 mm in a The 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 intermolar In primary dentition stage there is an increase of intermolar
width of 1.5 mm between 3-5 years width of 1.5 mm between 3-5 years
The first permanent intermolar width increases by 1.0 mm The first permanent intermolar width increases by 1.0 mm
between 8-13 years of age and decreases by 1.0 mm by 45 years between 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 dentition The arch length decreases in mixed and permanent dentition
stages as a result of uprighting of incisors and the loss of leeway stages 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 )