3. INTRODUCTION
• Malocclusion is a developmental
condition CAUSED in most cases by
distortion of normal development
and only a few cases caused by
PATHOLOGY.
• Although it is difficult to know the precise cause of most
malocclusion BUT we do know in general what the
possibilities are.
4. Multiple Factors
• Occasionally a single specific cause is
apparent e.g mandibular deficiency
secondary to trauma to TMJ or
characteristics malocclusion that
occur in some genetic syndromes.
• More often these problem result
from complex interaction among
multiple factors that influence
growth and development
6. By the middle of 19th century
different ideas was put forward to explain
possible causes of malocclusion
Here are some of the earlier concepts
on the aetiology of malocclusion;
-Kingsley: the importance of inter-
racial mixtures(marriage)
-Talbot: the role of endocrine glands
-Rogers: lip habit
-Brash: theory of inheritance
7. Aetiology of Malocclusion
Several attempts has been made to classify
aetiology of malocclusion among which are;
iii) Pre-eruptive abnormalities /Post eruptive
iv) Prenatal /Postnatal
v) Determining / predisposing
8. Aetiology of Malocclusion
GENERAL FACTORS LOCAL FACTORS
• Congential absence of teeth
• Anomalies of tooth size
• They affect all or greater part of the • Anomalies of tooth shape
occlusion. They include; • Abnormal labiel frenum
(A) Abnormalities in skeletal relationship • Premature loss of deciduos teeth
(B) Soft tissue factors • Supernumerary teeth
• Abnormal resorption of deciduous teeth
(C) Disproportion between tooth size and
• Delayed eruption of permanent teeth
ach length
• Abnormal eruptive path
• Ankylosis of deciduous teeth
• Proximal caries
• Improperly contoured restorations
9. GENERAL FACTORS
They affect all or greater part of the occlusion. They include;
(A) Abnormalities in skeletal relationship
(B) Soft tissue factors
(C) Disproportion between tooth size and
ach length
10. ABNORMALTIES IN SKELETAL RELATIONSHIP
• Refer to as skeletal factors
• Include the following abnormalities;
(i) Anterior-posterior mal -relationship
(ii) VERTICAL MALRELATIONSHIP
(iii) LATERAL MALRELATIONSHIP
Result from: differential development of maxillae and mandible
11. Skeletal factors
(i) Anterior-posterior mal relationship
skeletal pattern
Class II Malocclusion
Maxillary protrusion
MANDIBULAR RETROGNATHIA
Class III Malocclusion
Maxillary retrognathia
MANDIBULAR PROTRUSION
12. -it is HEREDITARY and ethnic in
origin in most cases
skeletal pattern
15. Other possibilities are:
differential development of maxillae and mandible
Anterior-posterior mal relationship
a- Foetal intrauterine moulding;
Pressure against mandible
- if the head is excessively flex against the chest,
- arm pressed against the face
16. b- Haematological e.g sickle cell anaemia patient can have Class II
skeletal pattern due to maxillary prognatism (Sickle cell gnathopathy)
17. c- Endocrine e.g hypothyrodism (Cretinism)-there
is reduce jaw growth as part of overall reduction
in body growth
19. Teratogens can disturb jaw growth if introduce at a time
when the jaw is developing
it can also lead to cleft
lip and palate leading to
class III skeletal pattern
20. VERTICAL MALRELATIONSHIP
There is (¹) excessive facial growth which increases the facial height and could
cause skeletal open bite
• Can result from mandibular
prognatism
due to (²) hyperpituitarism
Also caused by (³) condylar
hyperplasia
21. LATERAL MALRELATIONSHIP
Occasionally dental bases is
disproportional wide or
narrow causing lingual or
buccal cross bite of molars
although the axial
inclination of the teeth
appear correct
some of the causes of
anterior-posterior
malrelationship are also
responsible for this
abnormalities
22. GENERAL FACTORS
(A) Abnormalities in skeletal relationship
(B) Soft tissue factors
(C) Disproportion between tooth size and These include muscles, lips, tongue and cheek
ach length
23. (B) SOFT TISSUE FACTOR
These include:
- muscles,
- lips,
- tongue and
- cheek
This is a major factor in determining tooth position.
25. • The effects are as follows;
(i) Muscle dysfunction e.g Bell palsy-
The facial muscle
affect the growth of
the jaw in two ways;
-The formation of bone at the point of muscle attachment
depend on the activity of the muscle
-Growth of soft tissue carry the jaw downward and forward
26. (ii) Short lips-leads to
proclination of anteriors,
increase overjet and
occasionally open bite
(iii)Hyperactive mentalis muscle
(iv) Cheek/lip defect-causes
displacement or proclination
of the teeth to the affected (v)Tongue-e,g
regions Macroglossia
Extra-oral Muscles Intra-oral Muscles
27. How soft tissues could be A cause for malocclusion?
غير كفء
The presence of incompetent lips
failure of the lower lip to control the position of the upper incisors
Competent lips incompetent lips
28. غير كفء
The lips may be incompetent due to many reasons
1. Increased LFH
2. Mandibular retrognathia
3. Short upper lip
4. Incisor protrusion
29.
30. What does Soft Tissue Dysfunction Do?
ٍ َ ِ َ ْ َ ٍ ْ َ ُ َّ
إِنا كل َّ شيء خلَقناهُ بقدَ ر
31. What does Soft Tissue Dysfunction Do?
The Gothic Arch The Roman Arch
34. When the tongue rests in the roof of the mouth the teeth erupt
around the tongue forming a normal shaped and sized jaw.
The tongue is the scaffold for
the upper jaw
35. All of these children will have an underdeveloped upper jaw.
Those children who breath through the mouth or have the lips apart at rest will
not have the tongue in the roof of the mouth.
36. Aetiology of Malocclusion
GENERAL FACTORS
(A) Abnormalities in (B) Soft tissue factors
skeletal relationship
(C) Disproportion between
tooth size and ach length
37. (C)TOOTH SIZE AND ARCH LENGTH DISPROPORTION
• Basically HEREDITARY in origin
DISPROPORTION
• Patient inherit small arch from
one parent and large tooth size
from other parent leading to
crowding
• Or a combination of large
arch and small tooth size
resulting in spacing
40. Aetiology of Malocclusion
Classification
McCoy and Shepard (1956) a) Direct(determining) b) Indirected (predisposing)
Salzman a) Prenatal b) Postnatal
T.C white (1976 ) - Dental base abnormalities
- Pre-eruptive abnormalities(large frenum, tooth germ position)
- Post eruptive abnormalities(swallowing habit, suckling,
premature loss of deciduous teeth)
Moyers (1972) a)Heredity b)Developmetal Defects
c)Trauma d) Physical agents
e) Habits f) Diseases g)malnutrition
Graber - General (extrinsic) factors
- Local (intrinsic) factors
William Proffit (2005) (i) specific causes
(ii) Genetic influences
(iii) Environmental influences
43. Hereditary is significant in determining
the following characteristics:
• Tooth size
• Arch length and width
• Height of the palatal vault
• Crowding or spacing
• Overbite and overjet
• Position and configuration of muscles
• Tongue size and shape
• Character of the oral mucosa
44. Heredity also plays a role in:
• Congenital deformities
• Facial asymmetry
• Size and position of the jaws
• Oligodontia and anodontia
• Supernumerary teeth
• Variations in tooth shape
46. II. Congenital defects
The following examples could be considered
the most common congenital causes of malocclusion:
• Clefts of the lip and palate
• Cerebral Palsy
closure of sutures of the skull
• Crouzons syndrome
• Cleido-Cranial Dysostosis
• Cranial Synostosis
47. Cleft lip and Palate:
! A congenital defect showing GENETIC INFLUENCE
from one third to one half of all cleft palate children
has a familial history of this deformity.
The following characteristic features of
malocclusion are always concurrent with
congenital cleft lip and palate:
a) Anterior cross-bite
b) Bilateral or unilateral posterior crossbite
c) Malpositioning and rotation of the maxillary incisors
d) Deflect the teeth from their normal eruptive path.
48. (iii) ENDOCRINE DISTURBANCE Thyroid affect ERUPTION
Parathyroid (Calcium metabolism)
affect CALCIFICATION
HYPOTHYROIDISM
effects:
Hyperparathyroidism
• abnormal resorption pattern
Bone is replaced by fibrous tissue giving the
• Delayed eruption
ground glass appearance acceleration of
• Retained deciduous teeth
skeletal ossification
Effects:
Hyperthyroidism
• early eruption of both deciduous
effect:
&permanent teeth
•acceleration of skeletal ossification
• Loss of lamina dura, and cortical bone
•early eruption of both deciduous
(teeth loss)
&permanent teeth
50. DISTURBANCE OF NORMAL FUNCTION
Nasal Breathing Mouth Breathing
Normal Swallow Abnormal Tongue Thrust Swallow
Abnormal Habits
. Thumb and Finger Sucking :
- Lip-sucking and Lip-biting
- Finger Nail Biting
51. Abnormal Habits
a. Sucking Habits:
i. Thumb and Finger Sucking :
* Causse:
i. Improper or inadequate nursing.
i i . Insecurity or attention getting mechanism.
iii. Habit during eruption of teeth.
iv. Feeling of hunger.
v. Feeling of personal in adequacy
vi. A simple learn habit with no underlying
neurosis.
52. Phases
Thumb sucking habit could be divided into 3 phases:
(a) Phase I: Normal Subclinically
Significant Thumb-Sucking: From birth to 3 years.
(b) Phase II: Clinically Significant Thumb-
Sucking: From 3- 7 years
عسير
(c) Phase III :Intractable Thumb- Sucking:
after 7 years
53.
54. Clinical Features of Prolonged Active Thumb-Sucking:
i. Finger habit opens mouth beyond
postural resting position. The thumb
finger exerts a labial and a depressing
vector on the maxilla incisors as well as
lingual and depressing vector on the
mandibular incisors .
The resulted malocclusion may be
- labial tipping of upper incisors,
- lingual tipping and flattening of lower
incisors and
- severe ANTERIOR OPEN BITE.
55. ii ANTERIOR OPEN BITE resulted from
thumb sucking is characteristic round
well circumbeded open bite "fish
mouth appearance".
The anterior open bite
Resulted from
excessive eruption of posterior teeth along
interference with the normal eruption of
with separation of the jaws and alteration of
upper and lower incisors.
vertical equilibrium of the posterior teeth
56. The anterior open bite
tongue thrust
iii. Anterior tongue thrust swallow:
It become for the tongue to thrust forward
during swallowing in order to affect an
anterior seal.
57. iv. Maxillary constriction due to:
! Negative pressure within the mouth from
sucking action.
! Disturbance of horizontal equilibrium: when
the thumb is placed between teeth, the tongue
must be lowered with lack of tongue pressures
on the lingual surfaces of the upper posterior
teeth.
! Increase of cheek pressure:
because of the buccinator stretching along with
mouth opening and its active contraction during
the active sucking action
58. v. High vault palate with narrow nasal floor
occurred secondarily to the maxillary
constriction and to the upward pressure from
the finger against the anterior part of the
palate.
vi. The finger itself may show the effect of
habits. A callus or virus infection may
be formed due to sucking.
! From all the above the persistent thumb
sucking habit is capable of producing a picture
of class II division 1 malocclusion.
59. Factors that Affecting the Degree of Damage to Teeth and Investing Tissue:
1) Frequency of habit during the day. The
more frequency the more the damage.
2) Duration of habit: Duration of habit
beyond early childhood. The more duration
the more the damage.
3) Intensity of habit: passive insertion of
finger in mouth with no muscle activity is less
harmful than active sucking with contraction
of perioral musculature.
4) Position of digit
61. b)- Lip-sucking and Lip-biting
When the lower lip is repeatedly held
beneath the maxillary anterior teeth, the
result is:
! Labioversion of maxillary anterior teeth.
• Open bite.
• Lingoversion of mandibular anterior teeth.
62. Habits
Lower lip sucking
Proclination of the
upper incisors
Retroclination of the lower incisors
It is important that habits are stopped before treatment is commenced
63. C)- Abnormal Swallowing/ Tongue Thrust Habit
Protrusion of the tongue
against or between the anterior
dentition and
excessive circum-oral activity
during deglutition.
Innate behavior
Universal infant oral behavior for
children under the age of 6
years.
64. d)-Finger Nail Biting
* Incidence:
- Is absent under the age of 3 years.
- There is rapid increase at 6 years of age.
-- The habit should not be accepted as a
primary symptom of maladjustment.
Crowding rotation and attrition of the incisal
edges of incisors especially the mandibular
incisors. This malocclusion is due to the
untoward pressures introduced during nail
biting.
غير مرغوب فيه
65. e)- Mouth Breathing
* Types of Mouth Breathing:
• Pathological mouth breathing
• Habitual mouth breathing
• Habitual mouth breathing, by
removal of the cause and clearing
of nasal passages, patient still
breath from his mouth as a habit
66. * Causes and Types of Mouth Breathing:
• Pathological mouth breathing, one of the
following may result into obstruction of the
nasal air passage:
! Large adenoids.
! Diseased tonsil e.g. tonsillitis.
! Hypertrophy of nasal turbinate.
! Nasal deformity e.g. deflected nasal septum.
! Hypertrophy of lymphoid tissue in
the nasopharynx.
! High fever.
68. * Characteristic Features of Malocclusion:
Mouth Breathing:
1. Narrow V-shape maxilla with
high arched
2. Protruded maxilla with
protrusion of
upper anterior teeth
3. Broad mandible
4. Retroclination of the lower
incisors
5. Increase over-jet
6. Posterior cross-bite
7. Gingival and periodontal
disease
72. Skeletal factors
Genetic
Soft tissue factors
Aetiology OF malocclusion
Enviromental Dental factors
Prenatal factors Natal factors
Postnatal factors
Teratogenesis Trauma to the
condylar region Traumatic injury to the mandible TMJ
Irradiation
Intra-uterine fetal posture Infectious conditions such as
rheumatoid arthritis
Abnormal function such as oral
respiration, abnormal swallowing
Habits such as thumb sucking prevent
normal muscle activity
76. • Mendelian developed a different
• Edward Angle & his view which was that malocclusion is
contemporaries influenced the primarily the result of inherited
dentofacial proportions which may
finding that malocclusion is a
be altered by developmental
disease of civilization . variations, trauma ,or altered
function.
77. Etiology of Crowding and Malalignment :
1. Disproportion b/w jaw & tooth
size.
2. Environmental factors.
3. Mouth breathing alter the tongue-
lip/cheek equilibrium.
4. Hereditary factors.
78. Etiology of Skeletal Problems:-
Skeletal orthodontic problems
Causes of skeletal problems:
resulting from malposition or 1. Inherited patterns.
malformation of the jaws rather
2. Defects in embryologic
than irregularity of the teeth
development & genetic
syndromes (rare).
3. Trauma (common cause).
4. Functional influences.
79. Egs :-
1. Class II malocclusion have
tendency toward (retrognathic
mandible) due to heredity.
The more sever the case is
probably due to hereditary &
environmental effects.
80. 2. . Mandibular prognathism or Class III malocclusion
There is a definite familial & racial tendency
It is caused by:
1. Excessive mandibular growth due to
constant distraction of the condyle
from the fossa .
2. Large tongue
3. Respiratory needs .
4. Pharyngeal dimensions.
5. Hereditary factors (major cause).
6. Functional mandibular shifts (affect
teeth more than jaws).
81. 3. Open bite can be due to :
• Sucking habit .
• Tongue posture accompany nasal
obstruction.
• Excessive eruption of posterior
teeth.
• Hereditary factors.
82. Conclusion
• Whatever the malocclusion is it
will be always stable a/f growth has
been completed.
• Malocclusion ,after all is a
developmental problem.
