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2. INDIAN DENTAL ACADEMY
Leader in continuing dental education
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3. Aetiology can be described as the
science which deals with the causation
or origin of any disease. This can be
attributed to any branch of science.
Finding the cause is curing half the disease
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8. THE ORTHODONTIC EQUATION ELABORATED
ACT AT
CAUSE
ON
TIMES
PRODUCING
TISSUES
SOME PREDISPOSING 1.CONTINUOUS 1.NEUROMUSCULAR
OR
SOME EXCITING
TISSUE
INTERMITTENT
2.TEETH
1.HEREDITY
3.BONE AND
2.MAY ACT AT
2.DEVELOPMENTAL
CARTILAGE
DIFF. AGE
CAUSES OF UNKNOWN
4.SOFT TISSUE
LEVELS
ORIGIN
OTHER THAN
3. TRAUMA
MUSCLE
4.PHYSICAL AGENTS
5.HABITS
6.DISEASE
7.MALNUTRITION
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RESULTS
1.MALFUNCTION
2.MALOCCLUSION
3.OSSEOUS
DYSPLASIA
9. Dental crowding
can be defined as a
discrepancy between tooth size and jaw size
that results in misalignment of the tooth row
•
Arch length a measurement of space available in
the dental arch for alignment of teeth
Arch length
deficiency defined as a negative
difference between the space available in the
dental arch and space required to align the teeth
Arch length
discrepancy a difference between
the space available in the dental arch and space
required to align the teeth
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10. ETIOLOGY OF CROWDING
Disproportion bw arch size and tooth size or arch length discrepancies
Prolonged retention of deciduous teeth
Altered path of eruption
Premature loss of deciduous teeth
Delayed eruption of permanent teeth
Presence of supernumerary teeth
Trauma
Localized abnormal size and shape of teeth
Late horizontal growth of mandible
Mesial migration of buccal segments
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11. HEREDITY
Child
is the product of parents who have
dissimilar
genetic
material.
Thus
conflicting traits may be inherited from
both parents resulting in abnormalities.
Racial, ethnic
and regional inter-mixture
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12. According to Lundstrom there exists a number of human
traits that are influenced by the genes that include the
following
• TOOTH SIZE
• ARCH DIMENSIONS
• CROWDING
• ABNORMALITIES OF TOOTH SHAPE
• ABNORMALITIES OF TOOTH NUMBER
• OVERJET
• INTERARCH VARIATIONS
• FRENUM
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13. GENETIC INFLUENCES
MALOCCLUSION CAN BE INHERITED IN
TWO
WAYS
INHERITED DISPROPORTION BW SIZE OF THE TEETH AND
SIZE
OF THE JAWS WHICH WOULD CAUSE IMPROPER OCCLUSAL
RELATIONSHIP
INHERITED DISPROPORTION BW SIZE OR SHAPE OF UPPER
AND
LOWER JAWS WHICH WOULD CAUSE IMPROPER OCCLUSAL
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RELATIONSHIPS
14. PRIMITIVE POPULATION : MALOCCLUSION WAS LESS FREQUENT
CHARACTERISTICS OF CIVILIZATIONS
STOCKARDS EXPERIMENTS
CHUNG ET AL : HAWAIIAN MELTING POT
COMPARISON OF MONOZYGOTIC AND DIZYGOTIC TWINS
LAUWERYNS ET AL
CORRUCINI AND CO WORKERS
HARRIS AND JOHNSON IN BOLTON BRUSH GROWTH STUDY
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15. DEVELOPMENTAL DEFECTS OF
UNKNOWN ORIGIN
These are gross defects of rare type originating in
failure of differentiation at a critical period in
embryonic development
Congenital absence of muscles
Micrognathia
Facial clefts
Oligodontia
Anodontia
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16. CONGENITAL DEFECTS
SEEN AT TIME OF BIRTH
GENERAL
LOCAL
ABNORMAL STATE OF MOTHER
DURING PREGNANCY
MALNUTRTION
ENDOCRINOPATHIES
INFECTITIOUS DISEASES
METABOLIC/
DISEASES
ACCIDENTS AT CHILD BIRTH
MACROGLOSSIA/ MICROGLOSSIA
CLEIDOCRANIAL DYOSTOSIS
INTRAUTERINE PRESSURE
CLEFTS OF THE FACE AND
PALATE
ABNORMALITIES OF JAW DEV.
DUE TO INTRAUTERINE
PRESSURE
NUTRITIONAL
ACCIDENTAL
TRAUMA
TO
FOETUS BY EXTERNAL FORCES
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17. TRAUMA
PRENATAL/ BIRTH INJURIES
HYPOPLASIA
OF THE MANDIBLE
VOGELGESICHT
PRESSURE
OF KNEE OR LEG
FOETUS
HEAD
FLEXED
AGAINST THE CHEST
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TIGHTLY
18. POSTNATAL TRAUMA
FRACTURES OF THE JAW AND TEETH
HABITS MAY PRODUCE MICRO TRAUMA
TRAUMA TO THE TMJ
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20. HABITS
DELETRIOUS HABITUAL PATTERNS OF MUSCLE BEHAVIOUR
OFTEN ARE ASSOCIATED WITH PERVERTED OR IMPEDED
OSSEOUS GROWTH, TOOTH MALPOSITIONS, DISTURBED
BREATHING HABITS, DIFFICULTIES IN SPEECH, UPSET
BALANCE IN FACIAL MUSCULATURE AND PHYSIOLOGICAL
PROBLEMS
THEREFORE
ONE
CANNOT
CORRECT
MALOCCLUSION
WITHOUT INVOLVMENT IN SUCH REFLEX ACTIVITIES
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21. DISEASE
SYSTEMIC DISEASES
FEBRILE DISEASES KNOWN TO UPSET DENTITIONAL
DEVELOPMENT TIME TABLE DURING INFANCY AND EARLY
CHILDHOOD
MORE LIKELY TO AFFECT QUALITY RATHER THAN QUANTITY OF
GROWTH
MALOCCLUSION SECONDARY TO CERTAIN NEUROPATHIES AND
NEUROMUSCULAR DISORDERS
SEQUALAE OF TREATMENT OF SUCH PROBLEMS AS SCOLIOSIS
BY PROLONGED WEARING OF APPLIANCES TO IMMOBILIZE
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THE SPINE
22.
ENDOCRINE DISEASES
PRENATALLY
Manifest as hypoplasia of teeth
POSTNATALLY
Retard or hasten the direction of facial growth
Rate of ossification of bones
Time of suture closure
Time of eruption of teeth
Rate of resorption of primary teeth
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23.
LOCAL DISEASES
1)
NASOPHARYNGEAL DISEASES AND DISTURBED
RESPIRATORY FUNCTION
2)
GINGIVAL AND PERIODONTAL DISEASES
3)
TUMORS
4)
CARIES
A) PREMATURE LOSS OF PRIMARY TEETH
B) DISTURBANCES IN SEQUENCE OF ERUPTION
OF PERMANENT TEETH
C) LOSS OF PERMANENT TEETH
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24. ETIOLOGY OF LATE LOWER
ARCH CROWDING
MARGARET RICHARDSON
Late lower arch crowding: facial growth/ drift
( Eur J Orthod 1979:1; 219-225)
Late lower arch crowding in reln. to primary crowding
( Angle orthod 1982:52;300-312)
Role of the third molar in the cause of late lower arch
crowding (AJO-AO 1989:95; 79-83)
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25. Pressure
from the back of the arch
because of physiologic mesial drift, the
anterior component of the force of
occlusion on mesially inclined teeth,
mesial vectors of muscular contraction, or
the presence of a developing third molar
may cause forward movement of the
buccal teeth, with shortening of the arch
and an increase in crowding.
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26. Pressure
from the front of the arch
may cause reduction in arch length
and depth with resultant crowding.
SELMER AND OLSEN R The normal
development of the mandibular teeth and the
crowding of the incisors as a result of growth
and function. Dent Rec 1937;57:465-77.
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27. LATE MANDIBULAR GROWTH
CAN LEAD TO INCREASED PRESSURE
FRONT OF THE MOUTH
IN
Growth behaviour of the human bony
facial profile as revealed by serial cephs Angle
Orthod 1952;22:78-90.
LANDE
BJORK
AND PALLING, HUMER FELT AND
SLAGSVOLD AND SIATOWSKI
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28. A study of the correlation
between mandibular growth direction and
changes in incisor inclination, overjet,
overbite and crowding. Eur Orthod Soc
Trans 1975:131-40.
LUNDSTROME
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29. SKELETAL STRUCTURE/
COMPLEX GROWTH PATTERNS
CROWDING INCREASED DUE TO PARTICULAR
TYPE OF SKELETON/ SPECIFIC TYPE OF GROWTH
PATTERN (SAKUDA ET AL)
INCREASED LOWER ARCH CROWDING WAS SEEN
TO
BE
ASSOCIATED
WITH
INCREASED
MANDIBULAR PLANE ANGLE, LARGE OVERJET,
RETROGNATHIC FACE AND INCREASED OVERBITE
(MENG ET AL)
EXTREME DEGREES OF MANDIBULAR GROWTH
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INCREASED CROWDING (BJORK)
30. SOFT TISSUE MATURATION
DENTOALVEOLAR
STRUCTURES ARE
RESPONSIVE
TO
SOFT
TISSUE
PRESSURES AND ADAPT TO A
POSITION OF BALANCE OF LIPS
CHEEKS AND TONGUE
FRANKEL /LOFFLER
WOODSIDE
/LINDER ARONSON
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31. PERIODONTAL FORCES
TEETH ARE JOINED TOGETHER UNDER TENSION
BY THE TRANS SEPTAL FIBRES (PICTON AND MOSS)
ANY IMBALANCE CREATED BY THE TONGUE ON
ONE SIDE AND THE CHEEK AND LIPS ON THE
OTHER ARE COUNTER ACTED BY FORCES IN THE
PDL BY ACTIVE METABOLISM (PROFITT)
CONTINUOUS FORCE ON THE MANDIBULAR
DENTITION TO MAINTAIN PROXIMAL CONTACTS IN
A STATE OF COMPRESSION. FORCE INCREASED
DURING OCCLUSAL LOADING (SOUTHARD)
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32. TOOTH STRUCTURE
PECK AND
PECK
SMITH
ET AL/ PUNEKY ET AL/ GLEN ET
AL/ GILMORE AND LITTLE
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33. OCCLUSAL FORCES
ALTERATION
IN FUNCTION MAY
PRODUCE A DIFFERENT PATTERN OF
MASTICATORY
FORCES
OR
AN
OCCLUSION
WITH
PREMATURE
CONTACTS
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34. CONNECTIVE TISSUE CHANGES
BONE
LOSS AS A RESULT OF AGING
OR PERIODONTAL DISEASE MAY
ALLOW TEETH TO MOVE UNDER
PRESSURE
THEY
LIFE
CAUSE CROWDING IN LATER
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35. Diagnosis
Classification
According to amount of crowding in mixed dentition
(Hotz 1980)
of crowding
First degree
Second degree
Third degree
According to etiology of malocclusion
Primary = heriditary
Secondary = acquired anomaly
Tertiary
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47. PONTS ANALYSIS
Determination of sum of
incisors
Determination
of
measured premolar value
Determination
of
measured molar value
Determination
of
calculated premolar value
S.I x 100/ 80
Determination
of
calculated molar
S.I x 100/64
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48. CAREYS ANALYSIS
DETERMINATION
DETERMINATION
OF ARCH LENGTH
OF
TOOTH
MATERIAL
DETERMINATION
OF DISCREPANCY
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49. MIXED DENTITION ANALYSIS
CAN
BE DIVIDED INTO 2 CATEGORIES
THOSE IN WHICH THE SIZES OF UNERUPTED
CUSPIDS AND PREMOLARS ARE ESTIMATED FROM
MEASUREMENTS OF THE RADIOGRAPHIC IMAGE
THOSE IN WHICH THE SIZES ARE DERIVED FROM
KNOWLEDGE OF THE SIZES OF PERMANENT TEETH
ALREADY ERUPTED IN THE MOUTH
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53. Conventional method
4
mandibular incisors measured with a boleys
gauge
Unerupted
canines and premolars are obtained
by measuring the greatest M-D crown diameter
on radiographic images
Reduce
radiographic enlargement by using
Huckabas formula
x = y x’/ y’
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54. Space
required = sum of incisors + values
of canines and premolars
Space
available measured using brass
wire from M-B cusp of first permanent
molar to opposite molar
Amount
of discrepancy = space requiredspace available
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55. Tweed method
relations of axial inclinations of mand
incisors and basal bone made on lateral
cephs
FMA
is bw 21º – 29 º FMIA should be 68 º
º
FMA ≥ 30 º FMIA 65
FMA ≤ 20 º IMPA should not exceed 92 º
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56. Dist
bw the objective line and the line that
passed
through
the
actual
axial
inclinations of mand incisors was
measured with vernier calipers
Measured
value x 2 to include both right
and left sides
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57. Total space analysis
Method
is divided into three areas
Anterior
Tooth measurement = sum of mand incisors + radiographic
image of canines
Cephalometric correction
Soft tissue modification
Z angle is measured
Z angle + cephalometric correction
Upper lip thickness
Total chin thickness
Anterior deficit = Measured value – total space
required
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58. Middle
area
Tooth
measurement = crown widths of first permanent
mandibular molars + values of premolars obtained from
radiographs
Curve
of occlusion
right side + left side/ 2 + 0.5
Space
available
M-B cusp of primary first molar to D-B of
permanent first molars
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59. Posterior
area
sum of M-D widths of 2nd and 3rd molars
which are unerupted
permanent mandibular molars were
substituted for primary second molar
third molars not visible – wheelers
measurement of molar was used
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60. X
= y – x’/ y’
Space
presently available + estimated
increase or prediction = space available
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61. Littles irregularity index
Labiolingual
displacements of the digitized
anatomic contact points of anterior teeth
measured perpendicular to the arch form
from the mesial of left canine to mesial of
right canine ( AM J ORTH 75; 68:554- 63)
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69. PEA
FORCES
SHOULD BE KEPT LIGHT
SAGITTAL,
VERTICAL
ANCHORAGE
NEEDS
IDENTIFIED
LACE
AND
LATERAL
SHOULD
BE
BACKS AND BEND BACKS USED
POSTERIOR
SEGMENTS
SHOULD
BE
SUPPORTED WITH HEAD GEAR/ TPA IN MAX
ANCHORAGE CASES
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