normal concept of occlusion ? what is malocclusion ? classification of etiology of malocclusion

3. What is
Occlusion &
What is
Malocclusion ?

4. OCCLUSION :
The term “occlusion” has both static &
dynamic aspects.
• Static- the form , alignment and articulation of teeth
within & between the arches, the relationship of teeth
to their supporting structure.
• Dynamic – the function of the stomatognathic system
as a whole comprising teeth, supporting structure ,
TMJ, neuromuscular and nutritive sytems.
• Angle defined – “occlusion as the normal relation of the
occlusal inclined planes of the teeth when the jaws are
closed.”

5. OCCLUSION
• Andrews during the 1970s put forward –the six keys to normal
occlusion

6. MALOCCLUSION
• Malocclusion is a condition in which there
is deflection from the normal relation of
the teeth to other teeth in the same arch
and/or to teeth n the opposing arch

14. GRABER’S CLASSIFICATION
• Graber divided the etiological factors as local and
general factors and presented a very comprehensive
classification .
• Local factors General factors
These are responsible for
malocclusion produce a
localized effect confined
to one or more adjacent or
opposing teeth.
On the other hand these are
those that affect the body as
a whole & have a profound
effect on the greater part of
the dento facial structures.

15. GENERAL FACTORS

17. • According to Lundstrom there exists a no of human traits
that are influenced by the genes that include
• Abnormalities such as Microdontia,
Macrodontia are attributed to heredity
1. Tooth size
• The arch length and arch width are
believed to be inherited.
2. Arch Dimensions
• Probably result of uncoordinated
inheritence of arch length and tooth
material
3. Crowding
• Anomaly such as peg shaped laterals
shows high genetic predisposition
4. Abnormalities of
tooth shape
• Anodontia , oligodontia5. Abnormalities of
tooth number

18. • The horizontal overlap of the upper
and lower dentition – is believed to
be genetically influenced.
6. Overjet
• Discrepencies in the
transverse , sagittal and
vertical planes between the
upper & lower jaws can be
inherited.
7. Inter Arch
Variation
• Malocclusions such as Midline Diastema –
that may be due to abnormalities of the
frenum are to a large extent are
determined genetically
8. Frenum

19. • According to Harris & Johnson – a no of craniofacial parameters showed
significant genetic influence .
• These include the following distances:
o Sella- Gnathion
o Sella- Point A
o Sella – Gonion
o Nasion- ANS
o Articulare- Pogonion
o Bizygomatic Width
o Anterior Facial Height
• As so many traits show a strong genetic pattern a no of malocclusions
can be partly or solely attributed to genetic factors. These genetic
traits can be further influenced by existing pre-natal or post-natal
environment factors.

21. 1. Abnormal state of mother during pregnancy
2. Malnutrition
3. Endocrinopathies
4. Infectious diseases
5. Metabolic & nutritional disturbances
6. Accidents during pregnancy and childbirth
7. Intra uterine pressure
8. Accidental traumatisation of the foetus by
external forces.

22. • Abnormalities of jaw development due to intra-
uterine position.
• Clefts of the face and palate
• Macro and microglossia
• Cleidocranial dysostosis

24. CLEFT LIP & PALATE
• Clefts are evelopmental defects that occur as
a result of non fusion between the various
embryonic proocesses.
• Cleft patients may exhibit –
missing teeth
mobile teeth
rotations, lingual
crossbites etc

26. • Hutchinson’s incisors
• Mulberry molars
• Enamel deficiencies
• Extensive dental decay
• The maxilla may be smaller in size relative to
the mandible
• Anterior cross bite

28. • Maternal viremia associated with Rubella infection during early
pregnancy may result in infection of the placenta & fetus.
• Fetal cells become infected , growth rate reduced , deranged &
hypoplastic organ development – resulting in structural anomalies.
• Some of the features that can be seen are –
a) Dental hypoplasia
b) Retarded eruption of teeth
c) Extensive caries

30. • Absence of clavicle (collar bone) which may be unilateral or
bilateral ; partial or complete.
• Patient may exhibit --
a) Maxillary retrusion and possible mandibular protrusion
b) Over retained deciduous teeth and retarded eruption of
permanent teeth.
c) Presence of supernumerary teeth
d) Presence of short and thin roots

31. • The patient lacks muscular co ordination
• It usually occurs due to birth injuries
• The uncontrolled and aberrant muscle activity upsets the muscle
balance resulting in malocclusion .
• Exposure to radiation / infection , hypoxia – probably are the
causes of underdevelopment of some areas of the brain.

33. • Abnormal fetal posture – interfere with symmetric
development of the face (usually disappers as the age
advances)
• Maternal fibroids
• Amniotic lesions
• Maternal diet & metabolism
• Maternal infetions such as German measles and use of
certain drugs during pregnancy such as –Thalidomide can
cause gross congenital deformities including clefts.

34. a) Forceps delivery – injury to the Temporomandibular
Joint area – which may undergo ankylosis- such
patients show retarded mandibular growth & hence
hypoplastic mandible.
b) Cerebral palsy – characterised by muscle
incoordination . This may occur due to birth injuries ,
exposure to radiation or infection , hypoxia etc .
c) Traumatic injuries that cause condylar fracture –
growth retardation resulting in marked facial
assymmetry .
d) Milwaukee braces – that are used for the treatment
of scoliosis – derive support from the mandible.
Prolonged use – can cause marked mandibular
retardation

36. • includes – chicken pox, measles, scarlet fever etc
• Ameloblasts may be affected under increased body
temperature.
characterized by
 retardation in the rate of Ca deposition in bones and teeth
 Marked delay in tooth bud formation and eruption of teeth.
 Delayed carpel & epiphyseal calcification.
 The deciduous teeth are often over-retained & the permanent
teeth are slow to erupt .
 Abnormal root resorbtion
 Irregularities in tooth arrangement & crowding of teeth may
occur.

37. • Increase in the rate of maturation and an increase in
the metabolic rate.
• Premature eruption of deciduous teeth
• Disturbed root resorption of deciduous teeth
• Early eruption of permanent teeth
• Patient may have OSTEOPOROSIS which contra indicates
orthodontic treatment.

38. • Changes in Ca metabolism
• Delay in tooth eruption
• Altered tooth morphology
• Delayed eruption of deciduous and permanent teeth &
hypoplastic teeth
• Increase in blood Ca
• Demineralisation of bone & disruption of trabecular pattern .
• Interruption of tooth development – in growing children .
• The teeth may become mobile due to loss of cortical bone &
resorbtion of alveolar process.

39. • Acute febrile illness – slow down the pace of
growth & development.
• These conditions may cause a disturbance in
tooth eruption and shedding – inrease the risk
of malocclusion

40. • Nutritional deficiencies during growth may result in
abnormal development –causing malocclusion .
• These diseases are more common in developing countries
than in the developed world.
• Examples are – Rickets (vit D)
• - scurvy (Vit C/Ascorbic acid)
• - beri beri (vit B1/ thiamin)
• These can produce severe malocclusion and may upset the
dental development timetable.

43. • EFFECTS OF THUMB SUCKING :
• The severity of the malocclusion caused by thumb sucking depends
on the – duration , frequency & the intensity of the habit.
1. Labial tipping of the maxillary anterior teeth resulting in
proclination of the maxillary anteriors
2. The overjet increases.
3. Anterior open bite – as a a result of restriction of incisor eruption
and supraeruption of buccal teeth.
4. The cheek muscles contract during thumb sucking resulting in a
narrow maxillay arch , which pre disposes to posterior cross bites.
5. As a result of open bite, the child may also develop tongue thrust.
6. The upper lip is usually hypotonic while the lower part of the face
exhibits hyperactive mentalis activity.

45. • Clinical features :
1. Proclincation of anterior teeth
2. Anterior open bite
3. Bimaxillary protrusion
4. Posterior open bite in case of lateral tongue
thrust
5. Posterior cross bite

47. Posterior tongue thrust habit with
posterior open bite.

48. • Lip biting and lip sucking appear after forced discontinuation of
thumb or finger sucking
• Lip biting most often involves the lower lip that is turned
inwards & pressure is exerted on the lingual surfaces of the
maxillary anteriors. The patient may exhibit –
 Proclined upper and retroclinded lower anterisor
 Hypertrophic and redundant lower lip
 Cracking of lips
 NAIL BITING doesn’t produce gross malocclusion
 People in certain countries – middle edge exhibits what is called
the nut notch

50. • The mode of respiration influences the posture of
the jaw , the tongue , and to a lesser extent .. The
head.
• Altered jaw & tongue posture because of mouth
breathing can alter the oro-facial equilibrium thereby
leading to malocclusion.
• Most normal people indulge to mouth breathing when
they’re under physical exertion.

51. • Long and narrow face
• Short & flaccid upper lip
• Contracted upper arch with possibility of cross bite.
• Increased overjet as a result of flaring of the incisors.

52. • Mature swallow pattern develops at around 4-5 yrs. It is
characterised by –
I.Relaxation of the lips
II.Placement of the tongue behind the upper central
incisors
III.Elevation of the mandible until posterior teeth are in
contact.
• Retained infantile swallow pattern is defined as the undue
peristence of the infantile swallow even after normal time
of its departure.
• These patients occlude only on one molar –in each
segment.

53. • Speech is largely a learned activity,or
an acquired activity.
• A large no of muscles are involved in the
production of speech.
• It doesn’t make gross demands on the
peri oral musculature and hence speech
defects are rarely a cause for
malocclusion.

56. BRUXISM
• Psychological & emotional stresses have
been attributed as one of the causes.
• Occlusal wear facets can be observed
on the teeth .
• Fractures of teeth and restorations
• Tenderness & hypertrophy of the
masticatory muscles.

57. • Children who support their head by resting the chin
on their hand and those who hang their head so that
the chin rests against their chest – are observed to
have mandibular deficiency.

58. • Children are highly prone to injuries of the
dentofacial region during the early years of
life
When they learn to crawl, walk or during play
Most of these injuries go unnoticed and may be
responsible for non vital teeth that do not
resorb and deflection of erupting permanent
teeth into abnormal position .

59. LOCAL FACTORS

60. • In order to achieve good occlusion , the normal no of teeth
should be persent .
• Presence of extra teeth or absence of one or more teeth
predisposes to malocclusion.
• SUPERNUMERARY TEETH :
• Based on morphology supernumerary teeth are-
-peg shaped
-barrel shaped or tuberculate shaped
-Supplemental
-odontomes
• Over 75% of these teeth remain impacted in the bone & are only
diagnosed radiographically.

61. • Problems associated with supernumerary teeth :
1. Failure of eruption
2. Displacement or rotation of permanent teeth
3. Crowding
4. Pathology such as Dentigerous cyst formation & other complications
such as Migration into the Nasal cavity , maxillary sinus or hard palate.
MISSING TEETH :
• The following are some of the commonly missing teeth in decreasing
order of frequency .
-third molars
-maxillary Lateral Incisors
-mandibular second premolars
-mandiular incisors
Maxillary second premolars
• Absence of teeth may be unilateral or bilateral .
• Absence of one or more teeth predispose to spacing in the Dental arch.

62. • Absence of permanent teeth often results in
over retained deciduous tooth.

63. • MACRODONTIA
- Affects most often Upper central insicors & second premolars.
.and lower thirl molars.c
- Macrodontia may result in crowding while , smaller sized teeth
predispose to spacing.
- Fusion between two adjacent teeth or between a suprenumerary
tooth and a normal tooth may predispose to malocclusion .
- Most of these conditions show a positive family history.
MICRODONTIA
 Smaller teeth
 Hypopituitarism or exposure to radiation or chemotherapy
during dental development.
 Frequently seen in association with Down’s syndrome & various
types of Ectodermal Dysplasia.

64. • PEG SHAPED MAXILLARY LATERAL INCISOR
• Often accompanied by spacing & migration of teeth.

65. • ABNORMALLY LARGE CINGULUM :
• The presence of unexaggerated cingulum prevents
establishment of normal overbite & overjet.
• The involved tooth is usually in labioversion due to the
forces of occlusion
• DEFECTS LIKE AMELOGENESIS IMPERFECTA ,
HYPOPLASIA OF TEETH , FUSION AND
GEMINATION .
• DILACERATION

66. • Prior to the eruption of teeth, the maxillary labial frenum is
attached to the alveolar ridge with some fibres crossing over
lingually to the region of the incisive papilla .
• As the teeth start erupting , alveolar bone is deposited and the
frenal attachment migrates into a more apical position
• Rarely a heavy fibrous frenum is found attached to the
interdental papilla region. This type of frenal attachment can
prevent the two maxillary central incisors from approaching
each other.
• It is diagnosed by a positive blanch test
• midline diastema may also occur due to a no of causes such as –
-presence of unerupted mesiodens
- anomalies of tooth size and number.

68. • Loss of tooth before its permanent successor
is sufficiently advanced in development and
eruption –to occupy its place.
• Early loss of deciduous teeth can cause
migration of adjacent tooth into the space and
can therefore prevent the eruption of the
permanent successor.

75. Premature loss of second primary molar resulting in
impacted second premolar

76. • Early loss of anteriors most often doesn’t
produce any malocclusion
• The earlier the deciduous teeth are
extracted, before the successional teeth are
ready to erupt , the greater is the possibility
of malocclusion.
• In a person having arch length deficiency , or
crowding – the early loss of deciduous teeth
may worsen the existing malocclusion.

77. Space maintainer
..

78. Adequate space has been maintained in the arch for the second
premolar by the application of space maintainer after extraction of
the primary second molar

80. • Prolonged retention of deciduous anteriors usually results in
lingual or palatal eruption of the permanent successors.
• Prolonged retention of buccal teeth results in eruption of the
permanent teeth either bucally or lingually, or may remain
impacted.
• Some of the reasons for prolonged retention of decidous teeth –
o Absence of underlying permanent teeth.
o Endocranial disturbance such as hypothyroidism.
o Ankylosed deciduous teeth that fail to resorb.

82. • Congenital absence of the permanent teeth
• Presence of supernumerary tooth or odontome – that block the
path of erupting permanent tooth.
• Presence of heavy mucosal barrier ------- a surgical incision in
most cases accelerates the eruption.
• Sometimes , premature loss of deciduous teeth can result in
delayed eruption of the permanent teeth because of formation
of bone over the erupting permanent tooth.
• Endocrinal disorders such as hypothyroidism.
• Presence of deciduous root fragments .

84. • It could be due to
• Arch length deficiency
• Presence of supernumerary teeth
• Impacted tooth
• Retained root fragments
• Formation of bony barrier.
• The maxillary canines develop almost near the floor
of the orbit and travel down to their final position in
the oral cavity. Thus they are most often found
erupting in an abnormal position.

85. • Root surface is directly fused with the bone
• Absence of intervening periodontal membrane.
• These are called submerged tooth , because they fail
to erupt to the normal level
• At times, these teeth are totally submerged within
the jaw and therefore cause migration of adjacent
teeth into the space.

87. • Caries can lead to pramature loss of
deciduous or permanent teeth
• Proximal caries that hasn’t been
restored can cause migration of the
adjacent teeth into the space leading to
reduction in arch length.

88. • Over contoured occlusal restorations cause
premature contacts leading to functional shift
of the mandible during jaw closure.

89. • Undercontoured occlusal restorations
can permit the opposing dentition to
supra erupt.
• Proximal restorations which are under
contoured invariably result in loss of
arch length due to drifting of the
adjacent teeth to occupy the space.

91. • Class I malocclusion can be a discrepency either
within the arches and or in the transverse or vertical
relationship between the arches.
• The patient may exhibit dental irregularities such as
crowding, spacing, rotations, missing tooth etc.
• Local factors causing class I malocclusion may include
–
• - displaced or impacted teeth
• - anomalies in size , number & form of the
teeth.

94. • A deep incisor overbite can occur in the anterior region.
• Characteristic feature of this malocclusion is – the presence of
abnormal muscle activity.
• The upper lip is usually hypotonic , short and fails to form a lip
seal.
• The lower lip cushions the palatal aspect of upper teeth, a feature
typical of a class II, div 1 – referred to as “lip trap”
• The tongue occupies a lower posture thereby failing to couneract
the buccinator activity – resulting in narrowing of the upper arch
at premolar & canine regions – thereby producing a V shaped upper
arch.
• Another muscle aberration is a hyperactive mentalis activity

96. • The patient exhibits deep anterior
overbite
• The lingually inclined upper centrals give
the arch a squarish appearance, unlike
the narrow v shaped arch seen in div 1.
• The patient exhibits normal perioral
muscle activity.

97. • Can occur due to the following causes :
• excessively large mandible
• Forwardly placed mandible
• Smaller than normal maxilla
• Retropositioned maxilla
• Combination of the above