Development of occlusion

1. BY --- PRIYANKA PARIHAR
MDS 1st yr
Dept of Conservative Dentistry
& Endododontic
1

2.  Introduction
 Periods of occlusal development
Neo-natal period.
Primary dentition period.
Mixed dentition period.
Permanent dentition period
 Keys of occlusion
 Compensatory curve
 Conclusion
 References
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3.  The term occlusion is derived from the Latin word, ‘occluso’ defined as the
relationship between all the components of the masticatory system in
normal function, dysfunction, and parafunction .
 An ideal occlusion is perfect interdigitation of upper and lower teeth, which
is a result of developmental process consisting of the three main events -
 JAW GROWTH
 TOOTH FORMATION
ERUPTION
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4. PRE-DENTATE PERIOD
PRIMARY DENTITION PERIOD
MIXED DENTITION PERIOD
PERMANENT DENTITION PERIOD
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5. (last upto 6 months after birth )
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6.  This period starts soon after birth and lasts upto 6 months . During this period,
the neonate has no teeth
 The alveolar process at the time of birth is called the gum pads
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7. GUM PADS
 They are horseshoe shaped pads that are pink,
firm and covered with a layer of dense
periosteum
 They are divided into two parts by dental groove
(labiobuccal and lingual).
 The gum pad is further divided into 10 segments
by transverse groove; each segment has one
developing tooth sac.
 lateral sulcus, which is the transverse groove
between canine and 1st molar region.
 This is helpful in predicting inter-arch relation at
a very early stage.
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8. Anterior open bite relation between upper
and lower gum pads at birth
 The Maxillary gum pad is wider and longer than
the Mandibular
 Thus when they are approximated, there is a
complete overjet all around.
 The only contact that occurs is around the molar
region .
 This is called infantile open bite, which is
considered normal and helpful during suckling
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9. Natal tooth Neonatal teeth
(Present at birth) (Erupt in the first 30 days of life)
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10. • Superficial position of the developing tooth germ, which predisposes
the tooth to erupt early.
 Hereditary factors which was explained by Holt and McIntosh
 Natal and neonatal teeth are also found to be associated with
multisystem syndromes(eg;cranofacial dysostosis,) and developmental
abnormalities providing the evidence of genetic contribution
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11.  Risk of aspiration
 Traumatic ulceration--Riga-fede disease ---“neonatal sublingual
traumatic ulceration.”
Riga-fede disease 11

12.  A radiograph should be made to determine the amount of root development
and the relationship of a prematurely erupted tooth to its adjacent teeth.
 King and Lee recommended that inflamed gingival tissue around teeth
should be controlled by applying chlorhexidine gluconate gel 3 times a day.
 In some cases with sharp incisal edge of the tooth selective grinding is
advisable.
 Most prematurely erupted teeth are hyper mobile because of the limited root
development and there is danger of aspiration, in which case the removal of
the tooth is indicated. 12

13. (from 6TH month to 6 year)
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14. SEQUENCE OF ERUPTION
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15. (NIKHIL MARWAH PEDIATRIC DENTISTRY) 15

16. 16

17.  There are 48 teeth/parts of teeth present in the
jaw. At this time there are more teeth in the jaws
than at any other time.
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18.  The initiation of primary teeth occurs during first sixth weeks of
intrauterine life and the first primary tooth erupts at the age of 6 months.
 It takes around 2½ to 3½ years for all the primary teeth to establish
their occlusion.
 FEATURES INCLUDES
SPACING
Shallow overjet & overbite (Anterior Teeth Relationship)
vertical inclination of anteriors
 Molar Relationship
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19. A) Spaced dentition
 Usually seen in the deciduous dentition to accommodate the larger
permanent teeth in the jaws.
 More prominent in the anterior region, and are called ‘physiological
spacing’ or ‘developmental spacing’.
 The spaces present are of two types-
1. Primate spaces
2. Physiologic spaces
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20. PRIMATE SPACES
 Exist between the maxillary lateral incisors and the canines (present
mesial to maxillary deciduous canines) and mandibular canines and
1st deciduous molars (present distal to mandibular deciduous canines).
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21. PHYSIOLOGIC SPACES
 Present in between all the primary teeth and play an important role in
normal development of the permanent dentition.
 The total space present may vary from
• 0 to 8 mm with the average 4 mm in the maxillary arch
• and 1 to 7 mm with the average of 3 mm in the mandibular arch.
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22. B) Nonspaced dentition
 lack of space between primary teeth either due to small jaw or larger
teeth.
 This type of dentition usually indicates to crowding in developing
permanent dentition.
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23. 1 Overbite
 It is the distance, which the incisal edge of the maxillary
incisors overlaps vertically the incisal edge of the
mandibular incisors.
 The primary incisors erupt in a deep overbite which is
corrected by eruption of posterior teeth around five years
of age.
 The average overbite in the primary dentition is 2 mm.
2 Edge-to-edge bite
 When the incisal edges of the two incisors are in the
same plane. This is also called as a zero overbite.
 This is most common due to attrition, lengthening of
ramus and downward-forward growth of mandible. 23

24. 3 Overjet
 It is the horizontal distance between the lingual aspect of
the maxillary incisors and the labial aspect of the
mandibular incisors when the teeth are in centric occlusion.
 The average in primary dentition is 1 to 2 mm.
 At the age of 2 years it is seen often to be 4 mm with a
fairly continious decrease upto the age of 5years
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25.  Almost vertical inclination of anteriors.
Decidious
Permanent
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26. (MOLAR
RELATIONSHIP)
 The mesiodistal relation between the distal surfaces of
maxillary and mandibular 2nd deciduous molars is called as
terminal plane.
 This is of 3 types;
1. Flush terminal plane:
 If the distal surface of maxillary and mandibular deciduous
second molars are in the same vertical plane; then it is
called a flush terminal plane.
 It is usually most favorable relationship to guide the
permanent molars into class I
 It is seen in 74 %
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27. Flush terminal plane
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28.  2. Mesial-step terminal plane:
 The distal surface of the deciduous 2nd mandibular molar is more
mesial to that of the deciduous 2nd maxillary molar.
 Seen in 14 %
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29.  3. Distal-step terminal plane
 The distal surface of the deciduous 2nd mandibular molar is more
distal to that of the deciduous 2nd maxillary molar.
 Seen in 10 %
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30. Terminal plane prediction
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31. (Around 6 years- 12 years)
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32.  The period during which both the primary and permanent teeth are present
in the mouth together is known as mixed dentition.
 This phase begins at around 6 years with the eruption of 1st permanent
molars and lasts till about 12 years of age.
 Mixed dentition period can be divided into three phases
1. FIRST TRANSITIONAL PERIOD
2. INTER-TRANSITIONAL PERIOD
3. SECOND TRANSITIONAL PERIOD
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33. I. FIRST TRANSITIONAL
PERIOD
 This is characterized by emergence of 1st permanent molars and exchange of
deciduous incisors with permanent incisors.
Emergence of 1st Permanent Molars
 The anteroposterior relation between the two opposing 1st molars after
eruption depends on their positions previously occupied within the jaws,
sagittal relation between the maxilla and mandible.
 Occlusal relationship is established by the cone and funnel mechanism with
the upper palatal cusp (cone) sliding into the lower occlusal fossa (funnel).
 The mandibular molars are the first to erupt at around 6 years of age.
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34. ■ Early mesial shift
 The eruptive forces of 1st permanent molars are strong enough to push
the deciduous molars forward in the arch thereby utilizing the primate
spaces and thus establishing class I relationship
Early mesial shift
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35.  LATE MESIAL SHIFT
 Many children lack primate spaces and have a nonspaced dentition and
thus erupting permanent molars are not able to establish Class I relation .
 In these cases, the molars establish Class I relation by drifting mesially and
utilizing the Leeway space after exfoliation of deciduous molars and this is
called late mesial shift
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36.  EXCHANGE OF INCISORS
 The deciduous incisors are replaced by permanent
incisors during this phase.
 This period of transition is from 6½ to 8½ years.
 The permanent incisors are larger as compared to
their primary counterparts and thus require more
space for their alignment.
 This difference between space available and space
required is called the incisor liability
 This is 7 mm for maxillary arch and 5 mm for
mandibular arch.
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37. ■ Utilization of inter-dental spacing of primary
incisors:
 Averages 4 mm in the maxillary arch and 3 mm in
the mandibular arch.
■ Increase in inter-canine arch width:
 This occurs as the child grows. In males, it is 6 mm
for maxilla & 4 mm for mandible whereas in females,
it is 4.5 mm in maxilla & 4 mm in mandible.
■ Increase in inter-canine arch length:
 This is due to growth of jaws.
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38. ■ Change in inter-incisal angulations
 The angle between the maxillary and mandibular incisors is about 150°
in primary dentition, whereas it is about 123° in permanent dentition
thus allows more proclination and gaining space for incisor alignment.
 This is called incisor labiality
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39. II. INTER-TRANSITIONAL PERIOD
 In this period, the maxillary and
mandibular arches consist of permanent
incisors and permanent molars that
sandwich the deciduous canines and
molars.
 This phase lasts for 1½ years and is
relatively stable.
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40.  Root formation of emerged incisors, and molars continues, along with
concomitant increase in alveolar process height.
 Resorption of roots of deciduous canines and molars.
40

41. III. SECOND TRANSITIONAL PERIOD
 This phase is characterized by replacement of deciduous molars & canines by
premolars & permanent cuspids & the eruption of maxillary lateral incisors and
canines.
 This takes place around 9 to 11 years of age.
Replacement of Deciduous Molars and Canine
 The combined mesiodistal width of permanent canine and premolars is less
than that of deciduous canine and molars. This extra space is called Leeway
space of Nance
 And is utilized by molars to establish Class I relationship through late mesial
shift.
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42. Leeway space of Nance
It is 1.8 mm (0.9 mm on each side) in maxillary arch & 3.4 mm (1.7 mm
on each side) in mandibular arch.
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43.  The dimensions of deciduous 2nd molars is more than that of 2nd
premolars, this excess space is called as E-space
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44. ERUPTION OF MAXILLARY CANINE
 As the permanent maxillary canines erupt they displace the roots of
maxillary lateral incisors mesially. This force is transmitted to the central
incisors & their roots are also displaced mesially.
 Thus, the resultant force causes the distal divergence of the crown in an
opposite direction,leading to midline spacing.
 This is called Ugly Duckling Stage or Broadbent phenomenon.
 This self-correcting malocclusion is seen around 8 to11 years of age and
was first described by H Broadbent in 1937.
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45. 45

46.  This condition corrects itself after the canines have erupted. The
canines after eruption apply pressure on the crowns of incisors thereby
causing them to shift back to original positions.
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47. 47

48. The entire permanent dentition is
formed within the jaws after birth
except for the cusps of 1st molar,
which are formed before birth.
This period is marked by the
eruption of the four permanent
second molars
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49.  Some changes that can be seen in permanent dentition are:
Horizontal overbite decreases(Overjet ) by 0.7 mm between 12 and 20
years of age
Vertical overlap (Overbite)decreases up to the age of 18 years by 0.5 mm
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50.  The permanent incisors develop
lingual to the deciduous incisors
and move labially as they erupt.
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51. The premolars develop below
the diverging roots of the
deciduous molars
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52. At approximately 13 years of
age all permanent teeth except
third molars are fully erupted.
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53. 53

54. Andrew in 1970 put forward keys to occlusion after studying 120
patients with ideal occlusion. He hypothesized that the presence of the
following features is necessary for an ideal occlusion:
1. Molar inter-arch relationship
2. Mesiodistal crown angulation
3. Labiolingual crown inclination
4. Absence of rotation
5. Tights contacts
6. Curve of spee
7. Bolton’s discrepancy.
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55.  Mesiobuccal cusp of the maxillary 1st molar
should fall into the mesiobuccal groove of the
mandibular 1st molar
 And the distal surface of the Distobuccal
cusp of the upper 1st permanent molar
should make contact and occlude with mesial
surface of the Mesiobuccal cusp of the lower
2nd molar.
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56.  The angulation of the facial axis of every clinical crown should be
positive
 The gingival portion of the long axis of the all crowns must be distal
than the incisal portion
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57.  Crown inclination refers to the
labiolingual or buccolingual inclination
of the long axis of the crown
 Cervical area of crown is lingually
placed then it is called as positive
crown inclination and if it is more
bucally then it is called as negative
crown inclination.
 Maxillary incisors-positive, mandibular
incisors-negative.
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58.  The fourth key to normal occlusion is that the teeth should be free of
undesirable rotations
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59.  Contact points should be tight (no spaces).
 In absence of abnormalities such as genuine tooth size discrepancies,
contact point should be tight.
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60.  Occlusal plane should be flat with
curve of Spee not exceeding 1.5 mm.
 Intercuspation of teeth is best when the
plane of occlusion is relatively flat.
 During the adolescent dentition stage,
the curve depth decreases slightly and
then remains relatively stable into early
adulthood.(Am J Orthod Dentofacial
Orthop 2008;134:344-52)
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61. 61
 A deep curve of Spee results in a more
confined area for the upper teeth, creating
spillage of the upper teeth progressively
mesially and distally
 A flat plane of occlusion is most receptive
to normal occlusion
 A reverse curve of Spee results in
excessive room for the upper teeth

62. 62

63.  Bennett and McLaughlin in 1993 gave seventh key to normal
occlusion. i.e. the upper and lower tooth size should be correct.
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64. Curve of Spee
Curve of Wilson
Curve of Monson
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65.  The curve of spee given by F. Graf Von Spee in Germany in 1890
 It refers to the anteroposterior curvature of the occlusal surfaces
beginning at the tip of the mandibular cuspid and following the buccal
cusps of bicuspid and molar continuing as an arch through the condyle.
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66.  It is a curve that contacts the buccal and lingual
cusps tips of the mandibular posterior teeth.
 The curve of wilson is medio-lateral on each side of
the arch
 It helps in two ways
– Teeth aligned parallel to direction of medial pterygoid
for optimum resistance to masticatory forces.
– The elevated buccal cusps prevent food from going
past the occlusal table.
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67.  This curve is obtained by extending the curve of spee and curve of
wilson to all cusps and incisal edges , which forms a sphere of a 4 inch
radius, mandibular arch adopted itself to the curved segment of a
sphere
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68.  Occlusion, ideally aligned or malalinged is the result of an
complicated synthesis of genetics and environmental
relationship throughout the early developmental stages of
childhood.
 A knowledge of growth and development of occlusion helps
to differentiate abnormal from normal relation of teeth and
helps in diagnosis & treatment planning.
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69. Textbook of Pedodontics: Shoba Tandon.
Orthodontics the art & science: S. I. Bhalajhi.
Dental Anatomy, Physiology & Occlusion:
Wheeler.
Textbook of Pediatric Dentistry – Nikhil Marwah
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