Ch-3 Occlusion & Malocclusion Classification.pdf

CHAPTER 3
OCCLUSION-MALOCCLUSION
CLASSIFCATION
Presented by
Dr Abduselam K

2.1 NORMAL OCCLUSION
 Angle described normal occlusion as an evenly placed row of
teeth arranged in a graceful curve with harmony between the
upper and lower arches.
 According to Angle, the key to normal occlusion in adults is
the anteroposterior relationship between the upper and lower
first molars.
 Angle's concept of normal occlusion is essentially the
description of an ideal occlusion.

cont…
Angle stated that occlusion is a complex phenomenon involving
the:
Teeth
Periodontal ligament
The jaws
The tempero-mandibular joint
The muscles and
The nervous system.

cont…
Angle thought that the first molars and canines were the most
reliable teeth.
 His description of first molar and canine relationships in normal
occlusion was and still remains a fundamental observation on which
dental and orthodontic diagnosis are based.

2.2. Keys to normal occlusion
 We should understand what is normal occlusion to distinguish it
from malocclusion.
 The six keys to occlusion forwarded by Andrews helps us in
defining the normal occlusion more precisely.
 It is apparent that Andrew described an ideal occlusion rather
than a normal occlusion.

cont…
Normal occlusion occurs frequently in a population, whereas
ideal occlusion is rare.
The ideal occlusion described by Angle and Andrews serves as a
model of occlusal excellence that gives clinicians a treatment goal
to which they can aspire.

Andrews‟ six keys to normal occlusion
in the adult dentition.
1. Molar relationship:
 The mesio-buccal cusp of the upper first molar occludes with
the groove between the mesio-buccal and middle buccal cusp
of the lower first permanent molar.
 For a normal occlusion in addition it is necessary for the disto-
buccal cusp of the upper first permanent molar contact with
the mesial surface of the mesio-buccal cusp of the lower
second permanent molar.

cont…
2. Crown Angulations:
 All tooth crowns are angulated mesially (mesodistal tip).
 In teeth with normal occlusion the long axis of the coronal
portion of each tooth in the arch is such that the incisal/
occlusal portion is mesial to the cervical part.
 The degree of tip or angulations varies with each tooth.

Cont…
3. Crown Inclination:
 Inclination refers to the labio -lingual or bucco -lingual
inclination of the long axis of the crowns of the teeth.
 It varies from teeth to teeth
A. Incisors are inclined towards the labial surface.
B. Upper posterior are inclined lingually, similarly from the canine to the
premolars.
C. Upper molar crowns are inclined lingually slightly more than the canines
and premolars.
D. Lower posterior teeth are inclined lingually, progressively more from
canine to molars.

Cont…
4. Rotations:
 There should be well designed teeth along the arches with out
any rotations.
5. Spaces:
 There should not be any spaces present between the teeth and
tight contact points should be present.
6. Occlusal Plane:
 A flat occlusal plane is desired but generally it varies
from flat to a slightly curve of spee.
 It is measured from the most prominent cusp of lower
second permanent molar to the lower central incisors.

2.3 malocclusion
DEFINITION
 Malocclusion is any deviation from normal occlusion of teeth.
 It is unacceptable deviation – aesthetic and/or function from the
„ideal‟ occlusion.
 The teeth are in abnormal position in relationship to:
 The basal bone of the alveolar process,
 The adjacent teeth and/or
 The opposing teeth.

Factors that influence malocclusion
1. SEX: There is no prediction except for lower anterior
crowding common in males.
2. AGE: malocclusion percentage is relatively low in
deciduous dentition. Incidence of normal occlusion
in deciduous is about 51%; in mixed dentition it is
about 40% and in permanent dentition it is about 30%.
3. RACIAL: Malocclusion is more common when racial
intermixture is present. It is less common in an
isolated pure race.
 For example in Eskimos malocclusion is relatively low.

2.4 Angles classification malocclusion
 Edward Angle introduced a system of classifying
malocclusion in the year 1899.
 Angles classification is still in use almost 100 years of
its introduction due to its simplicity in application.
 Advantages of Classifying Malocclusion
A. Helps in diagnosis and treatment planning.
B. Helps in visualizing and understanding the problem
associated with malocclusion.
C. Helps in communicating the problem of malocclusion.
D. Helps for easy comparison of various malocclusions.

Types of Malocclusions
Malocclusion can be:
1. Individual teeth malocclusions or intra-arch malocclusions.
2. Maxillo -mandibular malocclusions.

1. Individual teeth malposition or intra-arch
malocclusions.
 In this case a tooth can be abnormally related to its
neighboring teeth.
 Such abnormal variations are called individual teeth
malposition or Intra-arch malocclusion.

Nomenclature of Commonly Seen
Individual Teeth Malpositions are:
1. Distal Inclination- Crown of the tooth tilted or inclined
distally.
2. Mesial inclination- Crown of the tooth tilted or
inclined mesially.
3. Lingual Inclination- Lingual or Paltal inclination of the
tooth also called Retroclination.
4. Buccal Inclination- Labial or buccal tilting of the tooth
also called Proclination.
5. Mesial Displacement- This refers bodily movement of
the tooth in a mesial direction towards the midline.

Cont…
6. Distal Displacement- This refers bodily movement of the tooth
in a distal direction away from the midline.
7. Lingual Displacement- This is a condition where the tooth is
displaced in a lingual direction.
8. Buccal Displacement- This is a condition where the tooth is
displaced bodily in a labial or buccal direction.
9. Infraversion - Refers to a tooth that has not erupted enough
compared to the other teeth in the arch. Also called Infra
Occlusion.

Cont…
10. Supraversion - This is a tooth that has over-erupted as
compared to other teeth in the arch. It is also called
Supra Occlusion.
11. Rotation- This refers to tooth movement around its
long axis.
12. Transposition- This refers where two teeth have
exchanged their places.
 Tipping (Abnormal inclination ) of the teeth: It
involves the abnormal inclination tilting of the crown,
with the root being in normal position.
 Bodily displacement: It involves abnormal location of
the crown as well as the root in the same direction.

2. Maxillo-mandibular malocclusions or
inter-arch malocclusion
 This condition is characterized by abnormal relationship
between two teeth or group of teeth of one arch to the other arch.
 This inter-arch malocclusion can occur in:
A. Sagittal plane of space malocclusion.
B. Vertical plane of space malocclusion.
C. Transverse plane of space malocclusion

A. Sagittal plane of space malocclusion.
I. Normal Occlusion - Class I (Neutroocclusion)
 When the jaws are at rest & teeth are in centric
occlusion, the mandibular arch is in normal
mesiodistal relationship to the maxillary arch.
II. Post-Normal Occlusion -Class II ( Distocclusion)
 Is a condition where the lower arch is more distally
placed when the patient bites in centric occlusion.
III. Pre-Normal Occlusion -Class III ( Mesiocclusion)
 Is a condition where the lower arch is more forwardly
placed when the patient bites in centric occlusion.

Centric Relation and Centric Occlusion
Centric Relation:- Is the relation of the mandible to the maxilla
when the mandibular condyles are in the most superior and
retruded position in their glenoid fossa with the articular disc
properly interposed.
Centric Relation also called ligamentous position or terminal
hinge position.
At Centric Relation both the condyles are simultaneously seated
most superiorly in their Glenoid fossa.

Cont…
Centric Occlusion :- is that the position of the mandibular
condyle when the teeth are in the maximum intercuspation.
Centric Occlusion also called interccuspal position or
convenience occlusion.

I. Deep Bite or Increased over Bite
 Is a condition where there is an excessive vertical
overlap between the upper and lower anterior teeth.
 Normally it is 2 -3 mms.
II. Open Bite
 Is a condition where there is no vertical overlap between the
upper and lower teeth.
 Thus a space may exist between the upper and lower teeth
when the patient bites in centric occlusion.
 This open bite can be Anterior or Posterior region.
B. vertical plane (Frankfort plane)
of space malocclusion.

c. Transverse plane of space malocclusion
This includes various types of cross bites.

Nomenclature of Commonly Seen Group
Irregularities are
1. Overjet:
 It is the horizontal overlapping between the upper and lower
anterior teeth.
 Normally it is 2 -3 mms.
 Overjet can be
A. Normal
B. Increased
C. Decreased
D. Edge to edge
E. Reverse overjet or cross bite

Cont…
2. Overbite:
 It is the vertical overlapping of upper and lower anterior
teeth.
 Normally 2 -3 mms
 Overbite can be
A. Normal
B. Deep bite -complete deep bite & Incomplete deep bite
C. Closed bite
D. Open bite

Cont…
3. Protrusion: A condition where the maxillary and/or
mandibular teeth are anterior to the normal position.
4. Retrusion: Condition where the maxillary and/ or
mandibular teeth are posterior to the normal position.
5. Crowding: Condition where there is positional
irregularity of tooth crowns.
6. Imbrication: Condition describing the teeth
(especially the lower anterior teeth) which are
irregularly arranged within the arch due to lack of
space for them.

Cont…
7. Spacing: Condition where space is present between the teeth.
8. Crossbite: Condition where there is an abnormal bucco - lingual
or labio -lingual relationship of teeth or where the lower teeth
overlap the upper teeth.
9. Scissor bite or buccal cross bite: Condition where there is an
abnormal bucco –lingual relationship of posterior teeth in which
the upper tooth/teeth are placed completely buccal to the lower
tooth/teeth.

Cont…
10. Open bite: Condition where there is lack of vertical overlapping
of teeth in centric occlusion.
11. Bimaxillary protrusion: Condition where both the upper and
lower teeth are protruded.
12. Bimaxillary retrusion: Condition where both the upper and lower
teeth are retruded.

Angle‟s Classification of Malocclusion
 The Most commonly used system of classifying malocclusion.
 Angle‟s classification of malocclusion is based on the following
criteria:
1. Angle‟s classification was based on the mesio -distal relation of
the teeth, dental arches and the jaws.
2. According to Angle, the maxillary first permanent molar is the
key to occlusion. He considered this tooth as fixed anatomical
points within the jaws.

Cont…
3. Based on the relation of the lower first permanent molar to the
upper first permanent molar, he classified malocclusions into
three.
1. Class I - Neutroclusion
2. Class II - Distoclcusion
A. Division 1
B. Division 2
3. Class III - Mesioclusion

1. Angel‟s class I Malocclusion
 There is a normal Antero Posterior relationship
between the maxilla and mandible.
 Angles class I malocclusion is characterized by the
presence of a normal inter-arch molar relation.
 The mesio-buccal cusp of the maxillary first
permanent molar occludes in the buccal groove of
mandibular first permanent molar.
 The patient may exhibit dental irregularities, or
Malocclusion such as:
-Spacing
-Rotations
-Malaligned
-Bimaxillary protrusion etc
-Crowding
-Misplaced/malposed
-Missing tooth etc.

Cont…
 Class I patient‟s exhibit normal skeletal relation and
also show normal muscle function.
 The lower dental arch is in normal relation to the upper
dental arch.
 Patient profile is normal or straight profile or
orthognathic profile.
 Another malocclusion that is most often categorized
under class I is bimaxillary protrusion where the
patient exhibits a normal class I molar relationship but
the dentition of both the upper and lower arches are
forwardly placed in relation to the facial profile.
 Approximately 60 – 70% of all the cases of
malocclusion fall into this class.

Cont…
Class I molar and incisor relationships.

2. Angle‟s class II Malocclusion
 This group is characterized by class II molar relation where the
disto buccal cusp of the upper first permanent molar occludes
in the buccal groove of the lower first permanent molar.
 Angle‟s sub-classified class II malocclusion into two divisions:
I. Class II Division 1
II. Class II Division 2

 Is characterized by proclined upper incisors with a resultant
increase in overjet.
 A 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 is cushions the palatal aspect of the upper teeth,
a feature typical of a class II, division 1 referred to as “lip trap”.
 The tongue occupies a lower posture thereby failing to
counteract the buccinators activity.
Class II Division 1

Cont…
The unrestrained buccinators activity results in
narrowing of the upper arch at the premolar and canine
regions thereby producing a V-shaped upper arch.
Patient profile is convex profile.
There is deep mento -labial sulcus.
Another muscle defect is a hyper active mentalis activity.
The muscle imbalance is produced by a hyper-active
buccinators and mentalis and an altered tongue position
that accentuates the narrowing of the upper dental arch.
Approximately 25 - 30% of all the cases of malocclusion
fall into this class.

Cont…
Class II Division 1 molar & incisor relation

Cont…
Class II Division 1 incisor relation

Class II Division 2
 As in class II Division 1 malocclusion, the division 2 also
exhibits a class II molar relationship.
 The classic feature of this malocclusion is the presence of
lingually inclined upper central incisors and labially tipped
upper lateral incisors overlapping the central incisors.
 Variation of this form are lingually inclined centrals and lateral
incisors with the canines labially tipped.
 The patient exhibits a deep anterior overbite.

Cont…
 The lingually inclined upper centrals give a squarish or
“U” shaped appearance, unlike the narrow V-shaped
arch seen in division 1.
 Patients profile is straight to mild convex profile.
 The mandibular labial gingival tissue is often traumatized
by the excessively tipped upper central incisors.
 The patient exhibits normal perioral muscle activity.
 An abnormal backward path of closure may also be
present due to the excessively tipped central incisors.
 Approximately 5 - 10% of all the cases of malocclusion
fall into this class.

Cont…
severe Class II division 2 malocclusion

Cont…
Half unit Class II Division 2molar & incisor relationship.

Class II Subdivision
 When a class II molar relation exists on one side and a class
I molar relation on the other, it is referred to as class II
subdivision.
 Based on whether it is a Division 1 or Division 2 it can be
called:
 Class II Division 1, Subdivision or
 Class II, Division 2, Subdivision

Difference between Class II Division 1 and
Class II Division 2 Malocclusion

Angle‟s class III Malocclusion
 Class III malocclusion exhibits a class III molar
relationship when the mesio -buccal cusps of the
maxillary permanent first molar occluding in the
interdental space between the mandibular first and
second molars.
 Class III malocclusion can be classified into
 True Class III
 Pseudo Class III

A. True Class III Malocclusion
True Class III Malocclusion
 This is a skeletal class III malocclusion of genetic origin that
can occur due to the following causes:
 Excessively large mandible
 Forwardly placed mandible
 Smaller than normal maxilla
 Retropositioned maxilla
 Combination of the above causes

Cont…
 The lower incisors tend to be lingually inclined.
 The patient can present with:
 A normal overjet
 An edge to edge incisor relation or
 An anterior cross bite
 The space available for the tongue is usually more.
 Thus the tongue occupies a lower position, resulting in a
narrow upper arch.
 Approximately 5- 10% of all the cases of malocclusion fall into
this class.

Cont…
Class III molar and incisor relationships.

B. Pseudo Class III malocclusion
 This type of malocclusion is produced by a forward
movement of the mandible during jaw closure, thus it
is also called “postural” or “habitual” class III
malocclusion.
 The causes of pseudo class III malocclusion:
A. Presence of occlusal prematurities may deflect the
mandible forward.
B. In cases of premature loss of deciduous posteriors, the
child tends to move the mandible forward to establish
contact in the anterior region.
C. A child with enlarged adenoids tends to move the
mandible forward in an attempt to prevent the tongue
from contacting the adenoids.

Class III subdivision
 This is a condition characterized by a class III molar
relation on one side and a class I relation on the other
side

Summary of the incidence of different types
of Angle‟s malocclusion
 Class I malocclusion:
 The most common type of malocclusion
 About 60 - 70 % of the general population has class I
malocclusion.
 Class II malocclusion
 Second common types of malocclusion.
 About 25 -30 % of the general population Class II Division
1 malocclusion as class II Division 1 malocclusion.
 Class II Division 2 malocclusion About 5-10 % of the
general population has class II Division 2 malocclusion.
 Class III Malocclusion
 The least common type of malocclusion.
 Less than 5 - 10% of the general population has class III
malocclusion.

Draw backs of Angle‟s classification
 Although the Angle‟s classification has been used for
almost a hundred years now, it still has a number of
drawbacks that includes:
1. Angle considered the malocclusions only in the antero -
posterior plane. He didn‟t consider malocclusions in
the transverse and vertical planes.
2. Angle considered the first permanent molars as fixed
points in the skull. But this is not found to be so.
3. Angle‟s classification cannot be applied if the first
permanent molars are extracted or missing.

Cont…
4. Angles classification cannot be applied to the
deciduous dentition.
5. Angles classification does not differentiate between
skeletal and dental malocclusions.
6. Angles classification does not highlight the etiology of
the malocclusion.
7. Individual tooth malpositions have not been considered
by Angles.

Lischer‟s Modification of Angle‟s
classification
Lischer substituted the term class I, II, and III given by
Angle with the terms Neutrocclusion, Distocclusion and
Mesioclusion. In addition to these, he added a few more
terms which designated certain other malocclusions.
Neutrocclusion: synonymous with Angles class I
malocclusion.
 Distocclusion: synonymous with Angle‟s class II
malocclusion. Post- Normal occlusion.
Mesiocclusion: synonymous with Angle‟s class III
malocclusion. Pre – Normal occlusion

Cont…
Lischer suggested the use of suffix “Version” to describe the
wrong position of individual teeth as follows
Bucco version- Buccocclusion: Buccal placement of a
tooth or a group of tooth.
LinguoVersion -Linguocclusion: Lingual placement of a
tooth or a group of tooth.
SupraVersion - Supraocclusion: When a tooth or group of
tooth have erupted beyond normal.
InfraVersion -Infraocclusion: When a tooth or group of
teeth have not erupted to normal level.

Cont…
Mesioversion: Mesial to the normal position.
Distoversion: Distal to the normal position.
Transversion: Transposition of two teeth.
Axiversion: Abnormal axial inclination of a tooth.
Torsiversion: Rotation of a tooth around its long axis.

Etiology of malocclusion
• Etiology in orthodontics is the study of the actual cause of
dento -facial abnormalities.
• One of the systems of classifying the etiology of malocclusion is
to divide them into
 General and
 Local factors.
 The general factors are those that affect the body as a whole and
have a profound effect on the greater part of the dento -facial
structures.
 The local factors are confined to the face, the jaws or the teeth
and may affect one or two adjacent and or opposing teeth.

Graber‟s Classification of Cause of
Malocclusion
A. General Factors
1. Heredity
2. Congenital
3. Environmental
4. Endocrine Imbalance
5. Metabolic Disturbances
6. Nutritional Deficiency
7. Abnormal pressure habits and functional distortions
8. Posture
9. Accidents and Trauma

Cont…
B. Local factors
1. Anomalies of numbers
2. Anomalies of tooth size
3. Anomalies of tooth shape
4. Abnormal labial frenum
5. Premature loss of deciduous teeth
6. Prolonged retention of deciduous teeth
7. Delayed eruption of permanent teeth
8. Abnormal eruptive path
9. Ankylosis
10. Dental caries
11. Improper Dental restorations

A. General Factors
1. Heredity
 Heredity has for long been attributed as one of the
cause of malocclusion.
 Another reason attributed for the genetically
determined malocclusion is the racial, ethnic and
regional inter-mixture which might have led to
uncoordinated inheritance of the teeth and jaws.

Effects of Hereditary
 Hereditary plays a significant role in determining the following
characteristics:
 Tooth size: - Microdontia
- Macrodontia
 Arch width and length
 Facial asymmetries
 Macrognathia and Micrognathia
 Abnormalities of tooth shape:- Peg shaped laterals
- Carabelli‟s cusp
- Talon cusp
 Abnormalities of tooth number: - Anodontia
- Oligodontia
- Supernumerary Supplemental teeth
 Low Frenum attachment----------midline diastema

Cont…
2. Congenital
• Congenital defects or developmental defects are
malformations seen at the time of birth.
• They may be caused by a variety of factors including:
 Genetic,
 Radiologic,
 Chemical,
 Endocrine,
 Infection, and
 Mechanical factors.

Some of the congenital conditions associated with
dental malocclusion are:
Abnormal state of the mother during pregnancy
Endocrinopthies
Infectious disease
Metabolic and nutritional disturbance
Accident during pregnancy and child birth
Intra-uterine pressure
Accidental traumatization of the fetus by external forces

Cont…
 Clefts of the face and palate: Patients may exhibit.
 Missing teeth
 Mobile teeth
 Rotations
 Crossbite
 Macro and Microglossia

Cont…
 Cleidocranial dysostosis: Is a congenital condition
characterized by unilateral or bilateral, partial or
complete absence of the clavicle.
 Patients may Exhibit
 Maxillary retrusion and possible mandibular
protrusion.
 Over retained deciduous teeth and retarded eruption of
permanent teeth
 Presence of supernumerary teeth
 Presence of short and thin roots

Cont…
Fig. Cleidocranial dysplasia. Defective development of the
clavicles allows this abnormal mobility of the shoulders.

Cleidocranial dysplasia.
A radiograph of the jaw of the father of the above patient. There
are many additional teeth but widespread failure of eruption.

Cont…
 Congenital syphilis : Patient s may manifest
 Hutchinson‟s incisors
 Mulberry molars
 Enamel deficiencies
 Extensive dental decays
 The maxilla may be smaller in size relative to the
mandible
 Anterior crossbite

Cont…
 Maternal Rubella infection: Maternal rubella an
infection during pregnancy is believed to cause wide
spread congenital malformation in the child. E.g.
 Dental hypoplasia
 Retarded eruption of teeth
 Extensive caries

Cont…
 Cerebral palsy: This is a condition in which patient‟s
lacks muscular coordination.
 It usually occurs due to birth injuries.
 The uncontrolled muscle activity upset the muscle
balance resulting in malocclusion.

3. Environmental
 There exist a number of prenatal and post-natal
environmental factors that can cause malocclusion.
I. Prenatal Factors
• prenatal influences that interferes with symmetric
development of the face include:
 Abnormal fetal posture during gestations
 Maternal fibroids – Uterine mass
Cont

Cont
Amniotic lesions – Chorioamnioitis
-cause premature rapture of the amniotic fluid-
preterm PROM (PPROM)
- may cause preterm deliveries and causes systemic
neonatal infection
-skeletal deformities may be seen due to
oligohydramnios following spontaneous rupture of
the membranes (SRM) in extreme prematurity.

Cont…
Maternal diet and metabolism
Maternal infection such as German measles and Use
of certain drugs during pregnancy such as
Thalidomide.
 Thalidomide is a sedative and hypnotic drug can
cause gross congenital deformities including clefts.

Cont…
II. Postnatal factors
A. Forceps delivery - can cause
temporomandibular joint injury which undergo
ankylosis and patient shows retarded
mandibular growth and thus have a hypoplastic
mandible.
B. Cerebral palsy – characterized by muscle in
coordination. Patient can exhibit malocclusion
due to loss of muscle balance.

Cont…
C. Traumatic injuries that cause condylar fractures
can cause growth retardation resulting in marked
facial asymmetries.
D. Presence of scar tissue such as burn or as a
result of cleft lip surgery may produce
malocclusion due to their restrictive influence on
growth.

Cont…
4. Endocrine Imbalance
• Endocrine glands exert a profound influence on the
formation, calcification and eruption of the teeth and
regulate the expression of the growth pattern of the jaws,
face and cranium.
• The endocrinal disturbance either retards or accelerates
the growth of the face in a downward or forward
direction.

Cont…
A. Hypothyroidism:
Retardation in rate of calcium deposition in bones and teeth.
Narrowing of dental arches and impaction of teeth.
 Delay in tooth bud formation and eruption of teeth.
Deciduous teeth are often over retained and the permanent teeth are slow to
erupt.
Abnormal root resorpition
Irregularities in tooth arrangement and crowding of teeth can occur.

B. Hyperthyroidism:
Increase in metabolic rate
Increase in elimination of calcium and phosphorous.
Premature eruption of deciduous teeth.
Early eruption of permanent teeth.
There is demineralization or osteoporosis of bone which
contraindicates orthodontic treatments.
In growing children, interruption of tooth development
occurs.
The teeth may become mobile due to loss of cortical
bone and resorpition of the alveolar process.

Cont…
C. Hypoparathyroidism:
 Parathyroid glands regulate the levels of blood calcium
and phosphorous metabolism.
 Can cause:
 Altered tooth morphology
 Delayed eruption of deciduous and permanent teeth.
 Hypoplastic teeth.

Cont…
D. Hyperparathyroidism:
 Produces increase in blood calcium.
 The dentin shows hypocalcification.
 There is demineralization of bone.
 In growing children, interruption of tooth
development occurs.
 The teeth may become mobile due to loss of cortical
bone and resorpition of the alveolar process.

Cont…
E. Hyperpitutarism:
 Hyperfunction of the pituitary leads to gigantism
in early life and acromegally in adult life.
 Acceleration of tooth eruption
 Enlargement of the tongue
 There is overgrowth of alveolar process in height
and width, resulting in spacing of teeth.

Cont…
5. Metabolic Disturbances
• Acute febrile diseases are believed to slow down the
pace of growth and development.
• These conditions may cause a disturbance in tooth
eruption and shedding thereby increasing the risk of
malocclusion.

6. Nutritional Deficiency
• Nutritional deficiencies during growth may result in
abnormal development causing malocclusion.
• Nutritional disturbances such as rickets, scurvy, and
beriberi can produce sever malocclusion and may
upset the dental developmental time table.

Cont
7. Abnormal pressure habits and functional
aberrations
 Abnormal sucking
 Thumb thrust and finger sucking
 Tongue thrust and tongue sucking
 Lip and nail biting
 Speech defects
 Respiratory abnormalities (mouth breathing)
 Tonsils and adenoids
 Psychogenetic and bruxism

Cont…
8. Posture
 Poor postural habits are said to be a cause for
malocclusion.
• Children who support their chin on their hand are
observed to have mandibular deficiency.

Cont…
9. Accidents and Trauma
• Children are highly prone to injuries of the dento-
facial region during their early years of life.
• 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 positions

B. Local factors
1. Anomalies of numbers
 In order to achieve good occlusion, the
normal number of teeth should be present.
 Presence of one or more teeth predispose to
malocclusion.
A. Supernumerary teeth
B. Missing teeth

A. SUPERNUMERARY TEETH.
• Teeth that are extra to the normal complement are termed
supernumerary teeth.
• These teeth have abnormal morphology and do not resemble a
normal tooth.
• Extra teeth that resemble normal teeth are called
supplemental teeth.
• A frequently seen supernumerary tooth is the mesiodens
which occurs in the maxillary midline.
• Un erupted mesiodens is one of the causes of midline
spacing.
• The supernumerary and supplemental teeth cause non-
eruption of adjacent teeth and can deflect the erupting
adjacent teeth in to abnormal locations.

B. MISSING TEETH
The following are commonly missing teeth in
decreasing order of frequency:
Third molars
Maxillary lateral incisors
Mandibular second premolars
Mandibular incisors
Maxillary second premolars

Cont…
2. Anomalies of tooth size
 An increase in size of teeth results in crowding while smaller
sized teeth predisposed to spacing.
3. Anomalies of tooth shape
 Abnormally shaped teeth predispose to malocclusion. - E.g.
peg shaped laterals
4. Abnormal labial frenum
 Abnormalities of the maxillary labial frenum are quite often
associated with maxillary midline spacing.

5. Premature loss of Deciduous teeth
• This refers to 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
the adjacent teeth into the space and can therefore
prevent the eruption of the permanent successor.

Cont…
6. Prolonged retention of deciduous teeth
• The following are some of the reasons for
prolonged retention of deciduous teeth:
 Absence of underlying permanent teeth
 Endocrinal disturbances such as hypothyroidism
 Ankylosed deciduous teeth that fail to resorb.
 Non-vital deciduous teeth that do not resorb

Cont…
7. Delayed eruption of permanent teeth
• Some of the causes are:
 Congenital absence of the permanent teeth
 Presence of supernumerary tooth can block the
erupting permanent tooth
 Presence of heavy mucosal barrier
 Premature loss of deciduous tooth leads to formation
of bone over the erupting permanent tooth.
 Endocrinal disorders such as hypothyroidism
 Presence of deciduous root fragments that are not
resorbed.

Cont…
8. Abnormal eruptive path
• One of the causes of malocclusion is an abnormal path
of eruption which could be due to:
 Arch length deficiency,
 Presence of supernumerary teeth,
 Retained root fragment, or
 Formation of a bony barrier.

9. Ankylosis
• Ankylosis is a condition where a part or whole of the root surface is
directly fused to the bone with the absence of the intervening
periodontal membrane.
• This most often occurs as a result of trauma to the tooth which
perforates the periodontal membrane.
• Ankylosis can also be associated with
Certain infections
Endocrinal disorders
Congenital disorders such as cleidocranial dysostosis????
• Clinically these teeth fail to erupt to the normal level and are there
fore called submerged teeth.

Cont…
10. Dental caries
• Caries can lead to premature loss of deciduous or
permanent teeth thereby causing migration of
contiguous teeth, abnormal axial inclination and supra –
eruption of opposing tooth.
• Proximal caries that has not been restored can cause
migration of the adjacent teeth in to the space leading to
arch length reduction.

11. Improper Dental restorations
• Over contoured occlusal restoration cause premature contacts
leading to functional shifts of the mandible during jaw
closure.
• Under contoured occlusal restoration can permit the opposing
dentition to supra erupt.
• Proximal restorations that are under contoured invariably
results in loss of arch length due to drifting of adjacent teeth
to occupy the space.
• Poor proximal contact also causes food enlodgement and
periodontal weakening of the tooth.

Ch-3 Occlusion & Malocclusion Classification.pdf

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