Development of Occlusion is necessary for knowing the eruption sequence of teeth. By knowing the eruption sequence of teeth we can make our treatment plan. Development of occlusion gives us the knowledge of various malocclusion and we can correct them and give proper treatment plan to the patient.

1. NEW HORIZON DENTAL COLLEGE AND RESEARCH INSTITUTE
DEPARTMENT OF ORTHODONTICS AND DENTOFACIAL ORTHOPAEDICS
SEMINAR ON
DEVELOPMENT OF DENTITION
SUBMITTED BY: GUIDED BY :
SARBAJIT HALDER DEPARTMENT OF ORTHODONTICS
INTERN (2018-’19) AND DENTOFACIAL ORTHOPAEDICS

2. CONTENTS
 Occlusion and occlusal guidance
 Stages of occlusal development
Prenatal development
Postnatal development
pre-dentition period
primary dentition period
mixed dentition period
permanent dentition period
 Transient malocclusion
 Clinical implications
 Conclusion
 References

3. OCCLUSION
“occlusio” – Latin word
Relationship between all the components of the masticatory
system in normal function, dysfunction and parafunction.
Occlusal guidance – concept emboided in clinical
management to develop perfect & healthy occlusion in
permanent dentition

4. Stages Of Occlusal Development
 Prenatal development
 Postnatal development
Pre-dentition period
Primary dentition period
Mixed dentition period
Permanent dentition period

5. Stages of dental development
Hellman(1929)
– classical & traditional
Barnett(1978)
– more clinically useful

6. PRENATAL DEVELOPMENT
 Tooth development
– 6th week of IU life
 Four stages
initiation
bud stage
cap stage
bell stage

7. POST NATAL DENTITION PERIOD
Pre-dentition period
–till eruption of primary teeth
Gum pads
UPPER
LOWER

8. Neonatal jaw relationships
 No precise “bite”/jaw relationship
 Ant. open bite is normal
> simpson & cheung - 2% of neonates have ant.open bite
relation
> oral habits - incr. incidence
 mouth – rich sensory system

9. Precociously erupted teeth
Natal teeth
Natal teeth – at birth
Neonatal – 1 mth
Mand. Incisors – 85%
Max. Incisors – 11%
Mand. Cupids – 3%
Max. cuspisd/molar – 1%
Synd:-Chondroectodermal dysplasia
-Hallermann Streiff
-Pachyonychia congenita
-Rigafede & Ellisuan creveland

10. Primary dentition period
Eruption of
primary teeth
 Movement of teeth towards
occlusion
 From 6th month – 2 ½yrs
 Estab. of prim. dent is
considered to take place at
3yrs
 Sequence: cent incisors
lat. Incisors
first molars
canines
sec. molars

11.  At 6-8 mnth age mand. cent. incisors emerges
 By 13-16 months all 8 prim. incisors emerges
 1st molar emerges at 16 months & contact opposing teeth a
several month later
before canines fully erupt
 Max. prim 1st molars often
erupt earlier than mand
 Primary max. canine at
19 (16-22) months
 Mand. canines at 20 (17-23) months
 Prim. 2nd mand. molars at 27 (23-31) months
 Prim. 2nd max. molars at 29 (25-33) months
Mean age of eruption of
prim. teeth (months)

12. 23 Months = 16 Erupted Teeth 27 Months = 20 Erupted Teeth
19 Months = 12
Erupted Teeth
15 Months = 8
Erupted Teeth
11 Months = 4
Erupted Teeth
7 Months = First
Tooth Erupts
“7+4” Guideline - ABDCE

13. Eruption disturbances
 Teething and systemic disturbances
 Size and shape of Primary teeth
 Anomalies
 Primary tooth resorption
 Ankylosis of primary teeth

14. Neuromuscular considerations
 Contact of opposing 1st prim molar is the beginning of develop
of occlusion & a neuromuscular system
 Mature neuromuscular movements – presence & articulation of
teeth, proprioception of periodontium
 As teeth appears – muscle effect necessary functional occlusal
movements
 Teeth – guided to occlusal position by functional matrix of
muscle during active growth-facial skeleton
 Arch formed by crowns of teeth – altered by muscular activity

15. Primary dental arches
 Arch form & width – established for both primary & perm
dentition by 9 months
 Alveolar & basal bone – shape of dental arches
 Substantial change – incre. anterioposterior dimensions

16. Arch length and width
 Arch length: ant. arch length
total arch length
 Arch width: intercanine width
intermolar width

17. Spacing in primary dentition
 Spaced dentition
Primate spaces
Physiologic spacing
 Closed dentition
 total space:
0-8mm(4) maxi
1-7mm(3) mand
Primate spaces

18. Spaces in primary dentition
Primate spaces Physiologic spaces

19. Occlusal relations
 Primary tooth development is independent of skeletal
maturation
 Dentition is complete after 2nd molars erupted
 All prim teeth except mand cent. incisors & max 2nd molar,
occlude with 2 tooth of opposing jaw
 Prim teeth – in normal alignment & occlusion after 2yrs and
roots fully formed by 3yrs

20. Incisor Relations
 Over bite – 2mm
 Over jet – 2-6mm(4)
 Interincisal angle:
1230 -prim dentition
1500- perm dentition
 Canine relation:
Class I – Mand. canine in
embrasure b/w max lateral
&canine
Class II – Mand. canine
distal to embrasure
123o
150o

21. Molar relations
Flush terminal plane – distal surfaces of
upper & lower 2nd molar straight line
Mesial step – distal surface of lower more
mesial to upper
Distal step – distal surface of lower more
distal to upper
Flush terminal plane
Mesial step
Distal step

22. Disorders of primary occlusion
 Prevalence of all malocclusion in prim occlusion is not
thoroughly reported
 Varies among ethnic and culture
 Boys have more class II & III molar relations
 Bruxism a “functional malocclusion” in 10% of all child
 Sucking habits shown to involve in malocclusion

23. Mixed Dentition Period
From 6 – 12 yrs of age
2 stages:
Early mixed dentition
- eruption of 1st perm molars
- exchange of incisors
Late mixed dentition
- exchange of canines & premolars
- eruption of 2nd perm molars

24. Eruption of
permanent
teeth

25. Eruption of 1st perm molars
First molar – key to permanent
occlusion, erupts by about 6-7yrs
Pathway of eruption of 1st permanent
molars
Max tooth germ – down & back
Mand tooth germ – up & forwards
Pathway errupt of 1st perm molar

26. Eruption of permanent 1st molar

27. First permanent molar
Early mesial shift
- physiologic spaces
Late mesial shift
- leeway space

28. Establishment of occlusion of 1st
permanent molar

29. Exchange of incisors
 Primary incisors
exchange with perm
incisors
 MD width 4
perm incisors > prim
- max-7mm
- mand-5mm
 Physiological spaces
will allow to
accommodate
Maxillary incisorsMandibular incisors
A
CI
LI
Incisor liability

30. Increase of inter canine width
-increases at time of eruption
of incisors
Increase of ant. length in dental
arch
-increase in antero-posterior
dimension
-perm incisor move 2-3mm
labially
Change of tooth axis of incisors
-perm incisors incline labial or
buccal
-so wider arch circumferances
Sex Arch Width
increased
Male Maxilla
Mandible
6mm
4mm
Female Maxilla
Mandible
4.5mm
4mm
123o
150o

31. Ugly duckling stage
Broadbent -1973
-Transient mal-alignment
-Sakuma 1960
70% of midline diastema &
80% spontaneous closure
Ugly duckling stage in 7yr old child

32. Exchange of laterals (canines & premolars)
correction of ugly duckling stage
Space available is limited
Leeway space
order of exchange of lateral teeth
-takes 1½ yrs to complete
-order: maxilla 4-3-5
mandible 3-4-5
-crowding common after canines exchanged
& its more in mand.
-if sequence changed to 4-3-5 or 4-5-3
leeway space not utilized efficiently
Leeway space of Nance
3.4mm mand(1.7mm each)
1.8mm maxi (0.9mm each)

33. Eruption of 2nd permanent molars
-2nd perm molars erupts at 12 yrs
-arch length reduced by eruptive force
prior to 2nd molar erupt
-arch circumference may become
shorter
-2nd perm molar may accentuate
crowding
-proxi caries or early xed 2nd prim molars
further loss of arch spaces
-early eruption to laterals
Lack of space when 2nd molar
erupts prior to laterals

34. Permanent dentition
Third molar eruption
Calcification can be as late as 14 yrs and eruption at 17-21 yrs
No significant incisor crowding
Mand 3rd molar impaction frequent in skeletal class II
Dimensional changes
Dental arch perimeter decrease in late adolescent & young adult
Occlusal changes
Decrease in overbite & overjet in 2nd decade due to forward
growth of mandible
Posterior occlusal changes due to mesial drift, interproximal wear

35. Transient malocclusion
Self correcting anomalies Correction(timing/factors)
I.Predentate period
a)Retrognathic mandible
b)Anterior open bite
c)Infantile swallow pattern
Differential & forward growth of mandible
Erruption of primary incisors
In 1st yr with introduction of solid diet
II.Primary dentition
a)Anterior deep bite
b)Flush terminal plane
c)Spacing
d)Edge to edge
Eruption of deci molars, attrition incisal edge
Eruption of 1st perm molar, leeway space
Eruption of 1st perm molar
Eruption of perm incisors
III.Mixed dentition
a)Anterior deep bite
b)Mandibular antr crowding
c)Ugly duckling stage
d)End on relation
Eruption of 1st perm molar
Tongue pressure, increase in intercanine width
Maxillary canine eruption
Eruption of 1st perm molar, Late mesial shift
IV.Permanent dentition
a)Overjet and overbite Eruption of perm molars, diff. growth of mand

36. Clinical implications
 Normal v/s ideal occlusion
“normal” – implies variations around an
average or mean value
“ideal” – connotes a hypothetical
concept or goal
-occlusion can labeled as normal ideal
cannot be seen
-difficult task is to determine where to
place individual teeth to achieve best
 Models of occlusion
-dentists duty to decide which “tricks”
be taught to patient for their own
benefits & all tricks cannot be
mastered by patients
Buccal view
Lingual view
Ideal intercuspation

38. CONCLUSION
 Development of Occlusion is necessary for knowing the
eruption sequence of teeth. By knowing the eruption
sequence of teeth we can make our treatment plan.
Development of occlusion gives us the knowledge of
various malocclusion and we can correct them and give
proper treatment plan to the patient. It also tells us about
various factors essential for smooth transition from
primary to permanent dentition which is necessary for
giving proper treatment plan.

39. REFERENCES
 Orthodontics The Art and Science 5th Edition- S.I. Bhalaji
 Textbook of Pediatric Dentistry 3rd Edition- Nikhil Marwah

40. THANK YOU!