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.
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Development of dentition
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
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)
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
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
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
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
37.
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