1. Development of occlusion
Presented by-
Kritika Sarkar
B.D.S Final year

2. Introduction
• Salzmann & Gregory defined occlusion as:
“The changing interrelationship of the opposing
surfaces of the maxillary & mandibular teeth
which occur during movements of the
mandible & terminal full contact of the maxilla
& mandibular arches.”
• According to Angle: “Occlusion is the normal
relation of the occlusal inclined planes of the
teeth when jaws are closed”.

3. • Occlusion is the sum total of many factors
such as:
– Genetic
– Environmental
– Muscle pressure
– Changes with:
• Development
• Maturity
• Aging.

4. Periods of tooth development
Pre-dental Stage
(0-6months)
Deciduous
dentition (6
months-6 years)
Mixed dentition
(6-12 years)
Permanent
dentition

6. Pre-dentate stage
•Pre dentate stage refers to the
period from birth to the
eruption of first deciduous tooth
in the oral cavity.
•Ideally ranges from birth to 6
months but a delay in eruption
of first deciduous teeth by 4-10
months is considered normal.

7. • Aka neonate’s mouth or gum pad stage.
• The alveolar arches at the time of birth
are called gum pads.
• The form of arches is determined in the
intra-uterine life.
• Leighton has outlined the various factors
that determine the size of gum pads as
follows:
– The state of maturity of infant at birth.
– The size at birth as expressed by birth weight.
– Size of developing primary teeth.
– Genetic factor

8. • Maxillary gum pad is
horse shoe shaped &
the gum pads extend
labially & buccaly
beyond those in the
mandible.
• They develop in 2
parts:
– Labio-buccal
(differentiates former to
the lingual)
– Lingual.
• Mandibular gum pads
U-shaped and are
anteriorly everted.

9. Maxillary gum pad
Gingival groove-
Separates gum pads from palate.
Dental groove-
Extends from the incisive
papilla, backwards to touch
the gingival groove in the
canine region & continues
forward in the molar region.
Transverse grooves-
Depressions between the 10
segments of the gum pads.
Lateral sulcus-
Transverse groove between the
canine & molar sac region.

10. Mandibular gum pad
• Like the upper
arch, there are 10
segments but are less
demarcated.
• The gingival groove
demarcates the lingual
extent.
• The dental groove runs
backwards, and laterally
in the canine region.

11. Relation of gum pads
At rest:
• An anterior open bite is present.
• Contact at the molar area only.
• Tongue is interposed between the
space.
• Maxillary gum pads is wider than
mandibular & there is total
overlapping of maxillary gum pad.
It lies in a class II type
relation, where the upper gum
pad is forwardly placed. This is a
transient &self correcting.
• The gum pads grow rapidly during
the 1st year of life & the growth is
more in the transverse direction.
• Length increases, mostly in the
posterior direction.

13. Deciduous dentition

14. Studied under
Development of primary Development of primary teeth
teeth occlusion
Calcification Eruption
Terminal Relation of
Type of
Spaces plane anterior
dentition
relations teeth

15. Development of deciduous teeth
Calcification:
• The factors that control primary teeth’s calcification
include:
– Genetic factors.
– Sexual dimorphism (calcification begins earlier in females and
hence the eruption is earlier).

16. • Eruption starts when root formation of primary teeth begin.
• A>B>D>C>E.

17. Types of primary dentition
Open type:
• Primary teeth with
spaces.
Closed type:
• Primary teeth without
spaces due to larger
teeth of small arch
length.

18. Terminal plane relations (Baume’s
classification)
Flush Distal
terminal step
Mesial
step

19. Development of primary occlusion
• Inter-dental Spacing.
• Physiologic spacing:
– This is present due to antero-posterior growth of jaws.
– In maxilla it is 4 mm & in mandible it is 3mm.
– It is preferable since the chances of crowding in the
succedenous dentition is minimal.
• Primate space:
– Aka Simian/Anthropoid space (also seen in monkeys).
– Present between:
• Lateral incisor & canine in the maxilla
• Canine & first molar in the mandible

20. B
C

21. • By 21/2 years of age, deciduous dentition is usually complete
& in function. And by 3 years of age the roots of all the
deciduous teeth are complete.
• The crowns of permanent first molars are fully developed &
the roots are starting to form.
• The crypts of the 2nd molar are now definite and occupy the
space formerly occupied by the 1st molar.
• By 3rd-6th year of age the development of the permanent
teeth continues, with the incisors most advanced.
• From 5-6 years, just before shedding of the deciduous
incisors, there are more teeth in the jaws than any other
time.
• Developing permanent teeth shift closer to the alveolar
border. Very little bone remains b/w permanent teeth &
there crypts and the front line of the deciduous teeth.

23. Features
• Deep bite: when the primary incisors erupt, the
overbite is deep. This might be due to vertical
inclination of the incisors. This is gradually
corrected by:
– Eruption of primary 1st molars.
– Rapid attrition of incisors.
• Overjet: initially it is more in primary dentition.
By movement of whole arch, the overjet
decreases gradually. Generally it is 1-2 mm for
primary dentition.

24. Mixed dentition

27. The concept of bite opener
• According to Schwarz; there are 3 periods of
physiologic raising of the bite, with the
eruption of:
– 1st permanent molar @ 6 years
– 2nd permanent molars @ 12 years
– 3rd permanent molar @18.

28. 6-7 years
Eruption of first permanent molars:
• The 1st molars erupt, the pad of tissue
overlying them creates a premature contact.
• Propioceptive responses conditions the child
against biting on the natural “bite opener”, &
thus the deciduous teeth anterior to the 1st
permanent molar erupt, reducing the
overbite.
• The upper and the lower molars show
different paths of eruption.
– Maxillary: buccal and distal
– Mandibular: lingual and mesial.

30. Early mesial shift
• In children with open primary dentition, the mandibular 1st
molars close the primate space distal to canine.
• Thereby, the flush terminal plain gets converted into a mesial
step.
• This allows the permanent maxillary first molars to erupt
into class 1 molar relationship.
• This is called “early mesial shift”.

31. Eruption of Incisors &Incisor liability
• The size of the permanent incisors is greater than there
deciduous counterparts, hence they need more space for
proper alignment. This difference in the space required and
available is known as incisor liability. (Described by Warren
Mayne, in 1969).
• Incisor liability for
– Maxilla is 7.6mm
– Mandible is 6mm.
• How is the space discrepancy is compensated?
• It is compensated by:
– Increased inter-canine distance (3-4mm)
– Inter-dental spacing.
– Labial eruption of the incisors.

33. 8 to 9 years-The “Ugly duckling” stage
• About this time, the deciduous central incisors
are lost & their permanent successors start their
eruptive path toward contact with the incisors of
the opposing arch.
• Usually the mandibular central incisors erupt
first.
• They erupt lingual to there deciduous
counterparts.
• Around the age of 8 yrs a physiologic midline
diastema is commonly seen in the upper arch. It
is also known as Broadbent’s phenomena.

36. 9-10 years
• The apices of the deciduous
canines & molars begin to
resorb.
• At this time in the
mandible, the combined width
of deciduous- cuspid, 1st & 2nd
molar is approximately 1.7
mm. And in maxillary it
averages to 0.9 mm.
• This differential for each of the
arches in the buccal segment
id known as “Leeway space”
(as described by Nance).
M-D width of:
C+D+E> 3+4+5
Leeway space = (C+D+E )-(3+4+5)

37. • It is this temporary increase in the arch length, often
prevents the inter-digitation of the permanent 1st
molars.
• They maintain an end to end relation until the 1st & 2nd
primary molars are lost.
• The flush terminal plane is eliminated & the correct
cusp & fossa inter-digitation occurs only after the
exchange of deciduous molars & canines for there
succedenous counterparts.
• The late mesial drift of the lower molars takes up the
greater leeway space that is present in the lower arch.
• If there is a distal step instead of flush terminal then a
developing Class II malocclusion is likely.
• A mesial step, may mean a developing Class III
malocclusion.

39. 10 to 12 years
• This stage involves replacement of primary
canines & molars by permanent canines and
premolars.
• In maxilla first bicuspid erupts before canine. The
canine and second premolar erupt at almost
same time.
• There is decrease in arch length, in both the
arches, as the first molars shift mesially which
enable the establishment of full cusp Class I
relationship from flush terminal. This is known as
the “Late mesial shift” of molars.

41. • Eruption of 2nd molar teeth occurs shortly
after the appearance of the 2nd bicuspid.
• The gingival pads overlying the 2nd molar
contact prematurely again, blocking open the
bite anteriorly, allowing the eruption of teeth
anterior to the 2nd molars. (This is the 2nd bite
opener as stated by Schwarz).
• The reduction in the overbite is minimal and
variable.

43. Permanent dentition
Teeth Maxillary (years) Mandibular (years)
First molar 6-7 6-7
Central incisor 7-8 6-7
Lateral incisor 8-9 7-8
Canine 11-12 9-10
First bicuspid 10-11 10-12
Second bicuspid 10-12 11-12
Second molar 12-13 11-13
Third molar 17-21 17-21

45. Features:
1. Overlap- in Class I occluding dentition, the
maxillary teeth are labial or buccal to the
mandibular teeth.
2. Angulation- bucco-lingual & mesio-distal.
3. Occlusion- with the exception of central incisors
and third molars, each tooth occludes with 2
teeth.
4. Arch curvature-
a) Antero-posterior curvature of the mandible= Curve
of Spee.

46. Curve of Spee

47. b) Corresponding curve in the maxillary arch is
called compensating curve.
c) Bucco-lingual curve from one side to the other is
called Monson’s curve.
5. Overbite: the normal overbite expressed in
terms of % in adult dentition is 10-30%.
6. Molar relationship: class I mesio-buccal cusp of
maxillary 1st molar occludes on the mesio-buccal
grove of the permanent mandibular 1st molar.
7. Dimensional changes:
a) Basal arch-this corresponds to the basal bone of
maxilla & mandible.
b) Alveolar arch-joins the tooth to the basal arch.
c) Dental arch-joins the combined mesio-distal widths
of the teeth.

49. 8. During the growth the dimensional values of
basal & alveolar arches change but the dental
arch remains constant.
9. There is reduction in arch circumference with
aging & it is more pronounced in mandible.

51. Bibliography
• Graber’s Textbook of orthodontics.
• Textbook of cranio-facial growth by Sridhar Premkumar.
• Evaluation, diagnosis & treatment of occlusal problems by
Peter E Dawson.
• Wheeler’s dental anatomy, physiology & occlusion (8th
Edition).
• Pediatric dentistry-Clinical approach by Goran Koch.
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