1. AETIOLOGY OF MALOCCLUSION
LOCAL FACTORS
Dr. Nabil Al-Zubair

2. ETIOLOGY OF MALOCCLUSION
Heredity Malocclusion
Heredity FACTORS
Acquired Malocclusion
Environment Effects

3. Malocclusion is associated with one or more of the following
Malposition Malrelationship
of Malocclusion of
teeth dental arches
Single teeth Antero-posterior
Rotation Class II
Tipping Class III
Displacement Vertical
infra-occlusion Openbite
Supra-occlusion Deepbite
Transposition T Transverse
Space discrepancy Crossbite
Crowding Scissorbite
Spacing

4. Etiology of malocclusion.
Malocclusion can occur as a result of different factors
which are inherited or acquired
1) Skeletal factors. Etiology of malocclusion.
2) Soft tissue factors.
3) Dental and local factors. Skeletal
factors
4) Combinations.
Soft tissue
factors Malocclusion
Dental and
local factors

5. Etiology of malocclusion
• Skeletal Factors;
1) Anteroposterior.
Skeletal Factors
2) Vertical. Skeletal factors
3) Transverse.
4) Combinations Anteroposterior
Class II
Class III
Vertical
Low angle Malocclusion
High angle
Transverse
Crossbite
Scissor bite

6. Etiology of malocclusion
Soft tissue factor.
1) Lips.
2) Tongue.
Soft tissue factor
3) Combinations.
Lips
Morphology
Function
Malocclusion
Tongue
Position
Size

7. Etiology of malocclusion – soft tissue factors

8. Dental & local factors

9. Etiology of malocclusion
Dental & local factors

10. Dental and local factors

11. Dental and local factors

12. LOCAL FACTORS IN THE AETIOLOGY OF MALOCCLUSION
I-Anomalies in Number of Teeth:
- Developmental Missing teeth III- Anomalies in Position of Teeth:
- Supernumerary (Extra-teeth) - Ectopic
- The early loss of deciduous teeth - Impaction
- Retained deciduous teeth - Transposition
- Loss of permanent teeth
IV-_ Habits:
- Finger sucking
II- Anomalies in Size & Form of - Tongue thrusting
Teeth:
Size:
- Microdontia
- Macrodontia V- Others :
Form - fraenum
- Peg lateral incisors - Trauma
- Dilaceration - Pathology
- Twin teeth (gemination/fusion) - Bad restorations
- Dens evagenatus

13. I-Anomalies in Number of Teeth:
- Developmental Missing teeth
- Supernumerary (Extra-teeth)
- The early loss of deciduous teeth
- Retained deciduous teeth
- Loss of permanent teeth

14. - Variations in tooth number
• absence of one or more
• Supernumerary teeth
of teeth
Hypodontia Hyperdontia

15. Hypodontia
A common condition
characterized by
developmental absence of
one or more primary or
secondary teeth excluding
the third molars
Aetilogy: Multifactorial with both It results from disturbance during initial
inherited & environmental factors stages of tooth formation ,initiation and
contributing to the condition proliferation

16. Classified according to its severity as:
The most commonly
missing teeth are:
• 1-2 missing teeth
Mild
• 3-5missing teeth
moderate
• ≥ 6missing teeth
Severe

17. Congenitally missing teeth
Missing of teeth can be:-
a. Complete (Anodontia).
b. Many teeth (oligodontia).
Both are rare & are associated with ectodermal dysplasia (systemic
abnormality).
C. Few teeth (hypodontia) is more common.

18. - Oral anomalies associated with hypodontia
Over-eruption
Delayed dental Severely rotated
of opposing
development premolars
teeth
Transposition Taurodontism Alveolar atrophy

19. Medical conditions associated with hypodontia
Ectodermal dysplasia:
• Hypodontia, Hypohidrosis (failure to sweat
leading heat intolerance & dry
erythematous skin, Hypotrichosis (sparse
hair), nail defects & Xerostomia
Down syndrome
Cleft lip & palate
Hemifacial microsommia

20. Missing of primary teeth lead to missing of
its permanent successor
• Bilateral congenital absence is more
frequent than unilateral.
• More frequent in permanent
dentition than in deciduous
dentition.
• The missing tooth always the most distal tooth of each segment
* Incisor segment >>> lateral incisor.
* Premolar segment >>> second
premolar.
* Molars segment >>> third molar.

21. Supernumerary teeth

22. Most commonly
Occur 10 times found in the
Males are twice
Defined as teeth more frequently anterior
as commonly
in excess of the in the maxilla maxillary region
affected than
normal series than the followed by the
females
mandible mandibular
premolar region
Supernumerary teeth

23. Prevalence:
• 0.3 – 0.8% (primary dentition)
• 0.1 – 3.8% (permanent dentition)
• A Supernumerary tooth in the
primary dentition is likely to be
followed by a Supernumerary in
the permanent dentition

24. Medical conditions associated with Supernumerary
Cleidocranial dysplasia:
• Aplasia or agenesis of the clavicles, Class III
malocclusion, multiple supernummeraries
Cleft lip ±palate
Gardner’s syndrome

25. • Multiple numeraries can be
seen in cleidocranial Dysplasia.

26. Types of supernumerary teeth

27. Types: Conical, tuberculate, supplemental & odontomes
An erupted mesiodens causing separation of
the upper central incisors

28. An upper anterior occlusal radiograph
also showing the presence of a supplemental B
supernumerary
A complex odontome preventing
eruption of 3.

29. Diagnosis:
1) Clinical examination: displacement
of erupted incisors or midline diastema.
2) A "vertex occlusal" RADIOGRAPH taken
through the long axis of the incisors gives an
indication as to whether supernumeraries are
palatally or labially placed.

30. Supernumerary Complications
Failure of Midline
Crowding
eruption diastema
Displacement or Root resorption
Prevention of
rotation of of neighboring
tooth movement
adjacent teeth teeth

31. supernumerary preventing eruption of 1.

32. The early loss of DECIDUOUS teeth

33. • Causes of Premature Loss
i. Extensive carious lesion.
ii. Accidents "trauma" lead to loss of the
tooth vitality and abscess formation whereby
their removal becomes a necessity.
iii. Child has much fever that decrease body
resistance with multiple abscess formation
and increase the possibility of premature loss.
iv. Accelerate root resorption of tooth.
v. Premature extraction in serial extraction
therapy.
vi. Diseases such as Rickets.

34. The effect on the developing dentition
depends on:
- the amount of the crowding ,
- the age of the patient &
- the tooth lost

35. The effects of early loss of deciduous teeth on the developing dentition
- the tooth lost
Deciduous - Minimal effect – some space loss if
incisors crowding
Deciduous canines - Centerline shift if unilateral loss
with some relief of incisor
crowding
- Space loss for permanent
canines
Premature lost of primary canine
1.5 years later of the same patient

36. Deciduous first - Small Centerline shift if crowding
molars with minimal relief of labial
segment crowding
- Mesial molar movement with
space loss

37. Deciduous second - Often no effect on centerline or
molars incisor crowding
- Mesial drift of molars with space
loss for second premolars

38. The effects of early loss of deciduous teeth on the developing dentition
Tooth lost Effect on permanent dentition Action required
Deciduous incisors - Minimal effect – some space loss - None
if crowding
Deciduous canines - Centerline shift if unilateral loss - If crowding, consider
with some relief of incisor balancing extraction to
crowding protect the centerline
- Space loss for permanent
canines
Deciduous first - Small Centerline shift if crowding - Consider balancing
molars with minimal relief of labial extraction or space
segment crowding maintenance
- Mesial molar movement with
space loss
Deciduous second - Often no effect on centerline or - Space maintenance except in
molars incisor crowding spaced arches
- Mesial drift of molars with space
loss for second premolars

39. Retained deciduous teeth

42. Loss of permanent teeth
The most common permanent tooth to be
extracted early is:
- the first permanent molar
- A permanent maxillary central incisors

43. The early loss of first permanent molar:
Extraction before the age of 8 years results in:
Significant distal migration of the second premolar which
may then become impacted
distal migration

44. A permanent maxillary central incisors:
Occasionally lost due to trauma
If there is crowding, space loss can occur (complicate later tooth replacement)

45. Early loss of primary teeth
Early loss of teeth will lead to dental arch
collapse, but it’s not the only cause for
crowding & Malalignment.
Collapse will be due to :
1. Mesial drifting of posterior teeth.
2. Distal drifting of incisors a/f canine & 1st
decidious molar loss.

46. II- Anomalies in Size & Form of Teeth:
Size:
- Microdontia
- Macrodontia
Form
- Peg lateral incisors
- Dilaceration
- Twin teeth (gemination/fusion)
- Dens evagenatus

47. Anomalies in Size of teeth
Microdontia Macrodontia
- genetically determined
- generalised or localised
Teeth smaller than normal Teeth larger than normal
Associated with hypodontia Associated supernumerary teeth
Predispose to spacing Predispose to crowding
The microdontia of maxillary lateral
incisor is associated with impaction of
the permanent maxillary canine

48. Anomalies of tooth form

49. Abnormalities in tooth size and shape will be due
to disturbances during morpho & histo
differentiation stages of its development.
Most common abnormality is seen in lateral
incisors & 2nd premolars .

50. - Peg lateral incisors

51. - Twin teeth (gemination/fusion)
Fusion:-
is teeth with separate pulp chambers
joined at dentin .
Gemination:-
is teeth with common pulp chamber.
They are almost similar ,so you should
count no of teeth.

52. Dilaceration
Formation of tooth at an angle manifested as a bent root due to
displacement of tooth germ
Clinical Applications
Delayed Eruptions
Difficult Tooth Movements
Interference with Adjacent Tooth Roots

53. - Dens evagenatus

54. III- Anomalies in Position of Teeth:
- Ectopic
- Impaction
- Transposition

55. INFRAOCCLUSION
- Variations in tooth position
- TOOTH IMPACTION
- TRANSPOSITION:

56. Ectopic eruption
It occurs as a result of a
permanent tooth bud
malposition. Ex:-
1. Mesial drifting of maxillary
first molar.
2. Mandibular 2nd premolar erupt
distally.
3. Impacted Maxillary canines

57. INFRAOCCLUSION
- occurs as a consequence of failure of eruption of a tooth
due to ankylosis (the anatomical fusion of cementum &
alveolar bone)
- Ankylosed tooth become submerges relative to its
nieghbours
- The first & second deciduous molars most commonly
affected
- Complications:
 Tipping,
 inhibition of vertical development of adjacent teeth
 Deviation of the dental centerline to the affected side
(the results of stretching of the transseptal periodontal fibers
that interconnect the teeth

58. Consequences of infraocclusion of a deciduous molar
Tooth Consequences
Infra-occluded deciduous Delay exfoliation
molar Progressive submergence with failure of alveolar
development
Difficult extraction often requiring surgery !!!!!
Permanent successor Delayed & abnormal eruption
Disturbed root development
Centreline shift
Developing occlusion Tipping of adjacent teeth
Localised posterior open bite
Higher frequency of canine impaction, hypodontia &
ectopic first permanent molar eruption

59. - Abnormalities in the position of teeth can also
arise as a result of
- TOOTH IMPACTION
- Excluding third molars, commonly impacted teeth
include:
 Maxillary canines
 Maxillary central incisors
 First permanent molars

60. - TRANSPOSITION:
- An abnormality where the position of
teeth is interchanged
- The most transposed teeth: The maxillary
canines & first premolars

61. - Primary failure of eruption:
- The most affected teeth: The first &
second permanent molar

62. Traumatic displacement of teeth
Dental trauma can lead to
development of
malocclusion in 3 ways:
1. Damage to permanent tooth
buds from injury to primary
teeth.
2. Drift of permanent teeth a/f
premature loss of primary
teeth.
3. Direct injury to permanent
teeth.

63. Trauma to primary tooth lead to 2 results:-
 Trauma to the permanent tooth crown &
disturbances in enamel formation &defect on
tooth .
The crown may be displaced relative to the
root causing less root formation & short root or
dilacerations

64. Abnormal frenum attatchment

65. Labial Frenum
Its ORIGIN in the inner surface of the upper lip.
However, its insertion changed by age as follow
• In infancy: Inserted in the region of the incisive
papillae.
• In early childhood: Inserted at the gingival crest at
the midline.
• Increasing age: The teeth erupt and the alveolar
process grows downwards and the frenum is found to
be further away apically from the gingival crest

66. Normal Labial Frenum
thin knife like edge formed of
double layer of fibrous tissue
covered with mucous membrane.
Abnormal Labial Frenum
thickened fibrous, fan shape in appearance
and taping downward to the alveolar crest
even after eruption of the permanent canines.

67. Normal Labial Frenum Abnormal Labial Frenum
Histologically the frenum fibers do not the fibers penetrating the V-
penetrate the shaped inter-maxillary suture
premaxillary suture attaching at different depth to
the connective tissues and
periosteum.

68. Abnormal Labial Frenum

69. Diagnosis
1. By clinical observation alone.
2. By "Blanching Test": pull of upper
lip upward and outward
lead to blanching of the interdental
papillae obviously observed
with the abnormal heavy fibrous
frenum.
3. Periapical radiograph:
V-notch of the interdental bone between
central incisors

70. Abnormal frenal attatchment
Lingual frenum Lower labial frenum

71. Abnormal Habits
. Thumb and Finger Sucking :
Nasal Breathing Mouth Breathing
Normal Swallow Abnormal Tongue Thrust Swallow
DISTURBANCE OF NORMAL FUNCTION