The presentation aims in giving a detailed knowledge on the etiology of malocclusion

1. ETIOLOGY OF
MALOCCLUSION
-V.VARSHINI

2. INTRODUCTION
• Comprehensive orthodontic management involves
identification of possible etiological factors and an
attempt to eliminate the same.
• It is of great value in preventive and interceptive
procedures.
• Etiology of malocclusion is the study of its cause or
causes.

3. CLASSIFICATION OF ETIOLOGY OF MALOCCLUSION
McCoy’s classification
Moyer’s classification
Salzmann’s classification
White and Gardiner’s classification
Proffit’s classification
Graber’s classification

4. MC COY’S CLASSIFICATION
Mc COY
Indirect/
Predisposing
causes
> Hereditary
> Congenital defects
> Prenatal abnormalities
> Acute/ chronic infection
> Metabolic disturbances
> Endocrine imbalance
> Unknown causes
Direct/
Determining
causes
> Missing teeth
> Supernumerary teeth
> Malposed teeth
> Abnormal labial frenum
> Malfunctioning muscles
> Premature shedding of
deciduous teeth
> Delayed eruption of
permanent teeth
> Improper dental restoration

5. MOYER’S CLASSIFICATION
Heredity
Trauma
Physical agents
Habits
Diseases
Malnutrition
Developmental defects of unknown origin

6. HEREDITY
Neuromuscular
Bone
Teeth
Soft parts
TRAUMA
Prenatal trauma
Birth injuries
Post natal trauma
PHYSICALAGENTS
Premature extraction
of primary teeth
Nature of food

7. HABITS
Thumb/ Finger
sucking
Tongue thrusting
Lip sucking/ biting
Nail Biting
Other habits
DISEASES
Systemic diseases
Endocrine diseases
Nasopharyngeal
diseases
Gingival and
periodontal diseases
Caries
Tumours

8. SALZMANN’S CLASSIFICATION
• The representation of
etiologic factors in
malocclusion embodies
prenatal and post natal
factors.
• It shows that the genetic,
differentiative and congenital
factors that make up the
prenatal elements, can
influence one or all of the
post natal components-
developmental, functional
and environmental.

9. WHITE AND GARDINER’S
CLASSIFICATION
White and Gradiner’s classification
Dental base
abnormalities
Antero-posterior
malrelationship
Vertical malrelationship
Lateral malrelationship
Disproportion of size between
teeth and basal bone
Congenital abnormalities
Pre-eruption
abnormalities
Abnormalities in position of
developing tooth germ
Missing teeth
Supernumerary teeth and
teeth abnormal in form
Prolonged retention of
deciduous teeth
Large labial frenum
Traumatic injury
Post eruption
abnormalities
Muscular factors
Premature loss of
deciduous teeth
Extraction of
permanent teeth

10. PROFITT’S CLASSIFICATION
Profitt’s
classification
Specific causes
Genetic
influences
Environmental
influences
1. Disturbances in
embryological
development
2. Skeletal growth
disturbances
3. Muscle dysfunction
4. Acromegaly and hemi-
mandibular hypertrophy
5. Disturbances in dental
development
 Equilibrium theory and
development of dental
occlusion
 Functional influence on
dentofacial development
> Masticatory
function
> Sucking and
other habits, Tongue
thrusting
> Respiratory
pattern

11. GRABER’S CLASSIFICATION
General
factors
Heredity
Congenital defects
Environmental
Predisposing
metabolic climate and
disease
Dietary problems
Abnormal pressure habits
and functional aberrations
Posture
Trauma and
accidents
Local
factors
Anamolies in
number
Anamolies in
tooth size
Anamolies in
tooth shape
Abnormal labial
frenum
Premature loss
of deciduous
teeth
Prolonged
retention of
deciduous teeth
Ankylosis
Dental caries
and improper
restoration

12. HEREDITY
• Heredity has long been attributed as one of the causes of malocclusion.
• Human traits that are influenced by the genes include (according to Lundstrom):
> Tooth size
> Arch dimension
> Crowding/ Spacing
> Abnormalities in tooth shape and number
> Overjet
> Inter-arch variations
> Frenum

14. CONGENITALDEFECTS
General
Abnormal state of
mother during
pregnancy
Malnutrition
Endocrinopathies
Infectious disease
Accidents during
pregnancy and
birth
Intra- uterine
pressure
Local
Abnormalities of
jaw development
Clefts of the face
and palate
Macro and
microglossia
Cleidocranial
dysostosis

15. COMMON CONGENITAL DEFECTS
• Cleft palate can be defined as a furrow in the palatal vault or breach in continuity of palate.
• Both dental and skeletal components are affected.
• Features commonly exhibited:
> Missing teeth
> Mobile teeth
> Rotations
> Cross bite
> Impacted teeth
> Supernumerary teeth
CLEFT OF THE LIP AND PALATE

16. TORTICOLLIS (WRY NECK)
• Shortening of the sternomastoid muscle causing profound changes
in the bone morphology of the cranium and the face.
• Bizarre facial asymmetries and uncorrectable malocclusions if not
treated early

17. CONGENITAL SYPHILIS

18. MATERNAL RUBELLA INFECTIONS
• Dental hypoplasia
• Retarded eruption of teeth
• Extensive caries

19. CLEIDOCRANIAL DYSOSTOSIS
• Congenital condition characterised by
unilateral, bilateral or partial or complete
absence of the clavicle. The following
features may be present.
• Maxillary retrusion and possible
mandibular protrusion.
• Retained deciduous teeth and retarded
eruption of permanent teeth.
• Supernumerary teeth
• Presence of short and thin roots.

20. CEREBRAL PALSY
• Patient lacks muscular co-ordination -> uncontrolled and aberrant
muscle activity -> upsets the muscle balance -> Malocclusion

21. ENVIRONMENT- PRENATAL FACTORS
FACTORS RESULTING IN
MALOCCLUSION
ABNORMALITY SEEN
Pressure against rapidly growing
areas
Distortion
Arm pressed against the face Maxillary deficiency
Head flexed against the chest Mandibular deficiency
Decreased amniotic fluid Small mandible
Cleft palate Upward displacement of tongue
Pressure released when there is
growth
Stickler syndrome
Thalidomide poisoning Gross deformities like cleft

22. ENVIRONMENT- PRENATAL FACTORS
TERATOGENS
Chemical and other agents capable of
producing embryologic defects if given
at critical time are called teratogens.

23. ENVIRONMENT- POST NATAL FACTORS
Trauma to mandible
Forceps delievery- TMJ
Damage, Cross bite
Ankylosis of TMJ
Prolonged mechanical
ventilation- Delayed
eruption of primary teeth
Prolonged oro-tracheal
intubation- Airway damage,
Palatal groove formation,
defective primary incisors,
acquired cleft palate

24. PREDISPOSING METABOLIC CLIMATE AND
DISEASE
HYPOPITUITARISM
• Dwarf
• Delayed shedding of primary teeth
• Delayed eruption of permanent teeth
• Crowding due to smaller arch
• Mandibular growth affected
HYPERPITUITARISM
• Large teeth and jaws
• Lips thick, tongue enlarged
• Accelerated condylar growth- Large mandible
• Teeth tipped bucally due to large tongue.

25. PREDISPOSING METABOLIC CLIMATE
AND DISEASE
HYPOTHYROIDISM
• Delayed eruption
• Abnormal resorption pattern
• Retained deciduous teeth
• Malposed teeth
• Gingival disturbances
HYPERTHYROIDISM
• Early shedding and eruption
• Atrophy of alveolar bone

26. DIETARY PROBLEMS
NUTRITIONAL DEFICIENCY
• Disturbancesinthe developmentaltimetable.
• Rickets,scurvyandberi-bericanproduceseveremalocclusions.
• Prematurelossof teeth/Prolongedretention.
• Abnormaleruptivepath.
• Poortissuehealth
• Poorabsorption-hormonal/enzymaticdeficiency.
• Decreasedfluorideintake-lossof teethdueto caries-malocclusion.

27. ABNORMAL PRESSURE HABITS AND
FUNCTIONAL ABERRATION
EQUILIBRIUM THEORY:
• • If an object is acted upon by a set of forces but remains in
the same
• position, then the forces must be in balance.
• • Dentition is in equilibrium.
• • Movement occurs when equilibrium is disturbed.
Primary
factors in
equilibrium
Forces from
periodontal
membrane
Intrinsic
forces of
tongue and
lip
Extrinsic
forces-
Habits and
orthodontic
appliance
Forces from
dental
occlusion

28. POSTURE
• Frequently suggested that poor posture can lead to malocclusion.
• Stooping with chin on the chest- mandibular retrusion.
• Child resting head on hand or sleeping on arm or fist- possible development of
malocclusion.
• May accentuate existing malocclusion.
• Role as primary etiological factor to be proved conclusively.

29. ACCIDENT OR TRAUMA
• Undiscovered traumatic experiences- significant in malocclusion.
• Eruptive abnormalities.
• Abnormal resorption.
• Loss of vitality.
• Both prenatal trauma & postnatal injuries- Dentofacial deformity

30. LOCAL FACTORS
ANOMALIES IN NUMBER
• In order to achieve good occlusion, normal number of teeth should
be present. Presence of extra teeth or absence of one or more teeth
predisposes to malocclusion.
• Heredity plays a strong part in anomalies in number of teeth.

31. ANOMALIES IN NUMBER-
SUPERNUMERARY TEETH
• Teeth that are extra to the normal
complement are termed supernumerary teeth.
• These teeth have abnormal morphology
and do not resemble normal teeth
• They result from disturbances during the
initiation and proliferation stages of dental
development.
• no definitive time when supernumerary
teeth may develop.
• may form prior to birth or as late as 10- 12
years of age.
• usually develop from a 3rd tooth bud
arising from the dental lamina near the
permanent tooth bud teeth.

32. Non-eruption of adjacent teeth Delay the eruption of adjacent teeth
Crowding in the dental arches.
Deflect the erupting teeth into abnormal
locations
SUPERNUMERARY
TEETH CAN CAUSE

33. ANOMALIES IN SIZE
• There should be harmony between the tooth size and the arch length,
and also between the maxillary and mandibular tooth size, in order to
have normal occlusion.
• An increase in size of teeth results in crowding while, smaller sized
teeth predispose to spacing.
• Anomalies of size of teeth can be of 2 types:
1. Microdontia
2. Macrodontia

34. ANOMALIES IN SHAPE
• Anomalies of tooth size and shape are often
interrelated. Abnormally shaped teeth predispose to
malocclusion.
• Anomalies of tooth shape include:
• 1. The presence of peg shaped maxillary lateral
incisors is often accompanied by spacing and migration
of teeth.
• 2. Abnormally large cingulum on maxillary incisors-
Prevent establishment of normal overbite and Overjet.
The involved tooth is usually in labio-version due to
the forces of occlusion.
• 3. Additional lingual cusp of mandibular 2nd
premolars-Increase the mesiodistal dimension of tooth

35. ANOMALIES IN SHAPE
• 4. Fusion-
• Fused teeth arise through the
union of 2 normally separated
tooth germs.
• 5. Gemination-
Results from attempt at division of single tooth
germ

36. ANOMALIES IN SHAPE
• 6. Congenital syphilis –
• It is often associated with hypoplasia of
maxillary and mandibular anteriors.
Characteristics of congenital syphilis are
“Hutchinson’s incisors” and “mulberry
molars”.

37. ANOMALIES IN SHAPE
• 7. Dilaceration –
• Dilacerated tooth often fails to erupt to
proper level and can thus interfere with
normal occlusion. They may also
complicate extraction of teeth and may
interfere with tooth movement and
alignment.

38. ANOMALIES IN SHAPE
• 8. Dens evaginatus –
• A developmental condition that
appears clinically as an accessory cusp
or a globule of enamel on the occlusal
surface between the buccal and lingual
cusps mainly of premolars.
It may result in incomplete eruption,
displacement of teeth and may interfere
with normal occlusion.

39. ABNORMAL LABIAL FRENUM
• Abnormal labial frenum shows spacing between the maxillary central incisors due to presence of the fibrous tissue
,labial frenum.

40. PREMATURE LOSS OF DECIDUOUS
TEETH
• Specifically, it refers to the stage of development of the permanent tooth that
will succeed the lost primary tooth.
• Premature loss can occur due to:
1. Caries
2. Trauma
3. Endocrinal disturbances like hyperthyroidism
4. Metabolic disturbances like hypophosphotasia
• When a primary tooth is lost before the permanent successor has started to
erupt, bone may reform atop the permanent tooth, delaying its eruption. When
its eruption is delayed, more time is available for other teeth to drift into space
that would have been occupied by the permanent tooth.

41. PROLONGED RETENTION OF DECIDUOUS
TEETH
Absence of
underlying
permanent
teeth
Endocrinal
disturbances
such as
hypothyroidism
and
hypopituitarism
Malposition of
erupting
permanent
teeth
Ankylosed
deciduous teeth
that fail to
resorb

42. DELAYED ERUPTION OF PERMANENT
TEETH
Early loss of a
primary tooth
might cause
formation of a bony
crypt over the
succedaneous
tooth.
Presence of a heavy
mucosal barrier can
prevent the
permanent tooth
from emerging into
the oral cavity
Presence of
supernumerary
tooth can block the
eruption of
permanent tooth
Presence of
odontomas or
other cysts and
tumors might
prevent the
permanent tooth
from erupting
Presence of
deciduous root
fragments that
have not resorbed
may block the
eruption
Presence of
ankylosed
deciduous teeth
may cause delay in
eruption of
permanent teeth
Congenital absence
of permanent teeth

43. ABNORMAL ERUPTIVE PATH
• This is usually a secondary manifestation of a primary disturbance.
• Some causes of abnormal eruptive pathway are:
1. In cases of arch length deficiency, deflection of the erupting tooth may be merely an
adaptive response to the condition present.
2. Presence of supernumerary teeth, retained deciduous teeth, root fragments, bony
barrier or mucosal barrier may result in abnormal eruptive pathway.
3. Traumatic displacement of tooth buds–
A deciduous tooth may be driven into the alveolar process, and though it may
erupt later, it may displace the developing successor in an abnormal direction.
4. 1st and 2nd permanent molars are occasionally impacted; 3rd are frequently impacted by
an abnormal path of eruption.
5. Coronal cysts can also cause abnormal eruptive paths.

44. ANKYLOSIS
• Commonly seen during 6-12 years of age.
• Trauma causing a part of periodontal membrane to perforate and a bony bridge is formed
joining the lamina dura and cementum.
• Commonly affects deciduous second molar.

45. DENTAL CARIES
• Cariescan leadto premature lossof deciduous
or permanent teeth therebycausing migration of
contiguousteeth,abnormal axialinclinationand
supra-eruption of opposing teeth.
• Proximal cariesthat has not beenrestoredcan
cause migration of adjacent teeth intothe space
leadingto a reductionin arch length.
• A substantialreduction in arch lengthcan be
expectedif severaladjacent teethinvolvedby
proximal cariesare left un-restored.

46. IMPROPER DENTAL RESTORATIONS

47. CONCLUSION
• Hence, it is essential for an orthodontist to know the Etiology of malocclusion for
better management of patient.