The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
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Diagnostic set up /certified fixed orthodontic courses by Indian dental academy
1. DIAGNOSTIC SET UP
INDIAN DENTAL ACADEMY
Leader in continuing dental education
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2. Seminar on,
Diagnostic Set up
Panoramic Radiography
Xeroradiography
Clark’s technique
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3. DIAGNOSTIC SET UP
Practical aid in treatment planning and
diagnosis.
Proposed by H.D. Kingsley.
It’s a procedure in which teeth are removed
and replaced in positions they will occupy after
experiencing mesial migration in an orthodontic
environment.
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4. Advantages –
1. To determine and visualise the resultant
occlusion before the teeth have been extracted
2. Possible to change the treatment plan on the
model by replacing some and removing other
teeth so that one can thoroughly examine all
possible occlusions.
3. Mainly useful in asymmetric extraction and
combined surgical orthodontic treatment.
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5. 4. Tooth size – arch length discrepancies can be
visualised by means of set up.
5. Also a step in construction of tooth positioner.
6. Patient can be motivated .
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6. Procedure
A set of well trimmed models made of deep
impressions of teeth and soft tissues.
Lines are drawn through buccal groove on the
mandibular first molars on to the soft tissue.
This act as a reference point.
A . 004 inch ribbon saw blade is used to cut
through the contact areas and separate teeth.
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12. The lower first permanent molars are replaced to a new
position they will occupy by mesial migration.
Deciding lower first molar position is the most important
decision in constructing the set up.
Factors influencing position of first molar set up
are –
– Size of the teeth
– Presence or absence of tooth crowding mesial to anchor
molars.
– Procumbency of anterior teeth.
– Missing teeth
– Age of the patient
– Treatment plan
– Tooth size related to jaw size.
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13. After all the above points have been considered, the
orthodontist must anticipate the behaviour of anchor
molar during treatment.
It again depends on –
–
–
–
–
Technique employed
The time requirement
Orthodontist’s ability
Patient’s cooperation
At this stage by studying the set up one can analyse that If anterior teeth – too far forward – Extraction – If
already extracted – more extraction.
If anterior teeth – lingual – Eliminate planned
extraction.
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14. Maxillary teeth are arranged according to mandibular
teeth to obtain best possible occlusion.
In most cases, same no. and type of teeth are removed
from maxillary arch as mandibular arch.
Exception –
– Badly broken down teeth
– Congenitally missing or deformed teeth.
– Single tooth extraction in lower arch
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15. ‘A Simplified wax set up technique’
by R.W. Knierim JCO- 1975
According to his procedure –
Plaster is filled to about 4 mm over gingival margin of
impression.
As the plaster sets rough grooves are made in near set
plaster to depth of 2mm.
When plaster is set it is removed and teeth are
numbered.
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16. Teeth are then separated using discs on a lathe to
slice root area, most teeth will now snap apart.
Root areas are then trimmed.
The impression are saved and kept moist.
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17. The trimmed dies are then reinserted in air dried alginate
impression
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18. Melted wax is then poured in impression holding the
dies, it should flow well in grooves.
.
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19. Similar grooves are then placed in surface of wax
as it hardens
Plaster is poured over wax surface to make base for model.
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20. ‘A simplified Diagnostic set up technique.’ by Dr.
Barry N. Resnick; 1979 JCO
According to his procedure –
The plaster is poured in impression only to the extent of
clinical crown.
Soft wax of 5 mm thickness is poured over crown dies.
Remainder of impression is poured with plaster and
allowed to set.
After separation from impression, the model consists of
two plaster section connected by wax.
Teeth are marked and can be repositioned in desired way
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26. Panoramic Radiography
Also called as Ortho pantomograph (OPG)
Rotational Radiography.
It is a radiographic technique for producing
single image of facial structures that includes
both maxillary and mandibular arches and
their supporting structures.
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27. Advantages1. Broad anatomic coverage
2. Simple procedure
3. Better tolerated by pts with gagging problems
4. Low radiation dose
5. Convenience of the examination.
6. Useful in pts who are unable to open their mouth
7. Full mouth IOPA – 15 mins and OPG – 3-4
mins.
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28. Disadvantages
1.
Magnification, Geometric distortion and overlapped
images.
2.
Resolution of fine anatomic details of peri-apical area
and periodontal structures is less.
3.
Poor image is obtained when sharp inclination of
anterior teeth towards labial or lingual side.
4.
The spinal cord superimpose on anterior region.
5.
Common to have overlapped teeth images ,
particularly in premolar area.
6.
Artifacts are common and may easily be
misinterpreted.
7.
Expensive
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29. Indications
1.
2.
3.
4.
5.
6.
To assess pattern and amount of root resorption of
deciduous teeth.
Useful in mixed dentition period to study the status of
unerupted teeth.
Presence or absence of permanent teeth: their size,
shape, position and relative state of development.
To view ankylosed and impacted teeth.
To diagnose presence of supernumerary teeth or
congenital absence of teeth.
To study the character of alveolar bone and
immediate lamina dura and periodontal membrane.
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30. 7. To study morphology and angulations of roots of
permanent teeth.
8. To study the path of eruption of teeth.
9. To diagnose fractures or pathologies of jaw.
10. To diagnose caries, periapical infections root
fractures etc.
11. Useful aid in serial extraction to study status of
eruption of teeth.
12. Can assess TMJ and Sinuses.
13. Assess shape, size and symmetry of condyles.
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31. To interpret OPG competently one
must have a thorough understanding
of the following :
1. Principles of Panoramic image formation.
2. Techniques for Patient positioning with head
alignment and their rationale.
3. Radiographic appearance of normal anatomic
structures.
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32. Principles of Panoramic image formation
First described by Numata and independently by
Paatero in late 1940s.
Movement of the film and objects about 2 fixed
centers of rotation.
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33. Movement of film and X- ray source about one
fixed center of rotation.
While disc 2 moves, the film on this disc rotates past the
slit.
It is critical that speed of the film passing the collimator
slit is maintained equal to the speed at which x-ray beam
sweeps through the object of interest.
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35. Focal Trough
It’s a 3-D curved zone or image layer in which
structures are reasonably well defined on OPG.
The images seen on OPG consists largely of anatomic
structures located within the focal trough.
Objects out of focal trough are blurred
magnified/ reduced or distorted.
The shape of focal trough varies
with brands of machines used.
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36. Movement of the film and x-ray source
about the shifting center of rotation.
Structures near the film will be sharply imaged.
Structures which are near x-ray source get magnified
and distorted and resultant image is not discrete.
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37. Ring at center
of FT.
Ring 5mm
anterior to FT
Ring 5 mm
posterior to FT
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38. Patient positioning and Head alignment.
Prepration of Patients.
– Removal of earrings or any other metallic objects in head and
neck region.
– Instruct patients to remain still.
– Drape with lead apron.
Patient Positioning
– Place the pt so that dental arches are located in middle of focal
trough.
– A-P positioning – by biting at bite block.
– Proper mid sagittal plane –proper head positioning –
cephalostat.
– Occlusal plane and chin must be properly positioned – FH plane
parallel with floor..
– Back and spine be erect with neck extended.
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41. If anterior teeth are located behind the FT
- Blurred
- Wide anterior teeth
If anterior teeth are located infront of the FT
-Blurred
-Narrow anterior teeth
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43. If skull tipped too far backward
Position the skull according to FH plane and check for
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occlusal plane
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44. If skull tipped too far forward
Position the skull according to FH plane and check for
occlusal plane
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45. Deviation in mid sagittal plane
Asymmetric image
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46. Positioning in mixed dentition stage
•The tooth buds should be in FT
•If additional supernumerary teeth
or impacted teeth has to be shown the
pt must be positioned with occlusal
plane steeply dorsally
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47. Positioning of the Tongue
Pt should press tongue against palate
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48. Radiation dose reduction
By using rare-earth intensifying screens.
Reduce the output by using filters infront of x-ray tube.
Eg. Lanex screens.
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50. The four Diagnostic regions in OPG
Dentoalveolar region
Mandibular region
TMJ,including retromaxillary
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and cervical region
Maxillary region
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53. Dentoalveolar region
• Shape and angulation of roots.
• Alveolar bone and periodontium
• Shows gentle curve of occlusal plane
• Missing 3rd molars and
• Presence of metallic restorations.
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57. Xeroradiography
Xeroradiography is the recording of
radiologic images by a photoelectric process
rather than the photochemical one used in
conventional radiography.
An electrostatic image of object is formed on a
‘ Xeroplate’ , a metallic plate
coated with Selenium.
An electrostatic image is printed on a paper in
such a manner that xeroradiograph is obtained.
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58. Advantages
Pronounced edge enhancement
A choice of positive and negative display
Good detail
Wide exposure latitude
No need of silver halide coated films.
Disadvantages
High radiation exposure
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59. Types of Xeroradiographic systems
Two types –
1. The Medical 125 system
– Used since 1970s.
– Used manly in Mammography and general
radiography.
– Also been used for cephalometric
radiography and tomography of TMJ
1. The Dental 110 system
Designed for dental Xeroradiographs
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60. Medical Xeroradiography
Conventional X-ray source is needed.
Image is recorded in Selenium coated plate.
Before use, selenium photoreceptors which are
stored in a unit called conditioner are given a
uniform electrostatic charge
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61. Processing of Xeroplate before exposure
Plate is subjected to Relaxation
process.
Eliminates old images and
artefacts from
surface.
Plates are then electrostatically
charged and inserted to cassette.
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62. Exposure of Xeroplate
Latent image
Latent image is converted to visible image by
process called Development, in unit called
Processor
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64. Positive Image
When a positive voltage is applied to back of of the
photoreceptor – negative toner particles get attracted to
the surface so, highly charged areas receive more
toner particles than discharged areas.
This results in positive image where
darkest areas corresponds to most
dense parts of anatomy.
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65. Negative image
When a negative voltage is applied to back of of the
photoreceptor – positive toner particles get attracted to the
discharged areas .
This results in negative image where darkest areas
corresponds to least dense parts of anatomy and dense
objects appear white.
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66. Dental xeroradiography
Dental 110 xeroradiogrphic unit system is similar to
medical 125 system in concept but its design is
physically different.
The image receptor plates are the size no. 1 and no. 2
films and fit well in oral cavity.
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69. Radiologic exposure conditions and resultant skin doses
in application of Xeroradiography to Orthodontic
diagnosis. AJO-DO, 1980 by Akihiko Nakasima (Japan )
Minimum xeroradiologic exposure conditions for Skull
projections, Schuller’s and TMJ projections and Hand
projections were established by 13 examiners and
relation b/w image production and radiation dose was
discussed in comparison with conventional film
techniques.
The advantages were finer and clearer images due to
edge effect and wider latitude.
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70. Landmarks on cephlaogram such as Sella, ANS,Basion,
etc were more clear and exactly set.
Outline of condylar process and articular fossa, the
trabecular pattern of mandible and interdental crestal
bone edges were more clear and distinct.
The main hazard was unavoidable larger skin radiation
dose . It was 2.4 to 16.2 times larger than conventional
film techniques.
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71. A cephalometric appraisal of Xeroradiography
by Chate – AJO-DO 1980
This study involved identification by four observers of
16 cephalometric landmarks on 12 xeroradiographs &
on 12 radiographs, on 2 separate occasions.
The conclusion was that neither technique provided a
significant intraobserver differences. However, for 8 of
32 variables xeroradiography produced a significant
reduction in intraobserver error in comparison to
radiography.
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73. Localization technique
Two methods are used in dentistry to obtain
3-D information –
1. To employ two films projected at right angle
to each other.
2. Tube shift/cone shift principle or Clark’s
technique or buccal object rule or SLOB rule.
Mainly used in Orthodontia to locate position
of impacted canine.
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74. Clark’s technique
C.A Clark described it in 1910.
Its based on Parallax principle in physics.
In this , 2 periapical films are taken, first is
taken as standard orthoradial projection, while
second employs a vertical or horizontal change
in central ray projection.
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75. The apparent movement of the object in this
radiograph will provide clue to its exact
location.
According to rule of thumb objects which
moves with central ray movement are actually
behind the reference object.
Its basis of SLOB rule, that is Same side
Lingual Opposite side Buccal
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76. Horizontal shift of central ray
Distal shift of cone
Cone shift
Cone shift
Standard
Standard
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77. Vertical shift of central ray
Standard
Standard
Vertical shift
Vertical shift
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78. References (Diagnostic set up)
1.
2.
3.
4.
Begg Orthodontics Theory & Technique – Kesling
Diagnosis and treatment planning
in Orthodontics – Van der Linden
A Simplified wax set up technique by Dr. R.W.
Knierim JCO-1975.
A simplified Diagnostic set up technique by Dr. Barry
N. Resnick; 1979 JCO.
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79. References (Radiology)
1.
2.
Oral radiology – Goaz & White.
A Colour Atlas of Dental Radiology – Friedrich A
Pasler.
Essentials of Dental Radiography – Orien N Johnson.
Principles of Dental Imaging – Langland.
Orthodontics - T. M .Graber.
Radiologic exposure conditions and resultant skin
doses in application of xeroradiography to
Orthodontic diagnosis by Akihiko Nakasima AJODO, 1980 .
A cephalometric appraisal of Xeroradiography
by Chate AJO-DO 1980.
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81. Index
According to Russell, an index is defined as
‘A numerical value describing the relative status
of the population on a graduated scale with definite
upper and lower limits which is designed to permit and
facilitate comparison with other population classified
with the same criteria and the method.’
In the orthodontic context index is described as –
‘A rating or categorizing system that assigns a
numeric score or alpha numeric label to a person’s
occlusion.’
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82. General requirements of an Index.
- WHO 1977
1.
2.
3.
4.
5.
6.
Reliable
Valid
Acceptable to profession and public.
Require minimal judgement
Administratively simple
Cheap
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83. Ideal occlusal index should possess the
following properties1.
2.
3.
4.
5.
Reliability
Validity
It should be amenable to modifications.
It must yield quantitative data.
It should lend itself to rapid application by trained
examiners.
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84. According to Jamison H.D. and Mc Millan R.S
requirements of ideal orthodontic index used
for epidemiologic studies are –
1. Simple, accurate, reliable and reproducible.
2. Objective and yield quantitative data.
3. Differentiate b/w handicapping and non handicapping
malocclusions.
4. Quick examination.
5. Amenable to modifications.
6. Usable either on patient or on study model.
7. Measure degree of handicap.
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85. Types of Indices ( according to WHO)
Occlusal Classification
– Angle’s classification by Angle in 1899
– Incisor classification by Ballard and wayman, 1964
Skeletal classification by Houstaon et al, 1993
Malocclusion
– Occlusal index by Summers 1971
– Handicapping Malocclusion Assessment Record
(HMAR) by Salzmann, 1968
– Index of Treatment Need by Evans and Shaw 1987
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86. Treatment assessment
– Little’s irregularity index by Little 1975
– Peer Assessment rating by Richmond et al, 1992
Cleft Outcome
– Goslon Yardstick by Mars et al, 1987
– 5Year olds’ Index by Atack et al ,1997
Periodontal
– Plaque Index by Stilness & Loe , 1964
– Gingival Index. by Loe & Stilness, 1963
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87. Types Of Indices
According to Shaw , Richmond and O’Brien
Diagnostic Classification
– Angle’s classification
– Incisor classification
Epidemiologic indices
– Study prevalence of malocclusion in population.
– Eg 1.Summer’s occlusal index.
2. Registration of malocclusion described by Bjork,
Krebs and Solow
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88. Treatment need ( Treatment priority) indices.
– Categorize malocclusion according to levels of treatment
needs.
– Eg 1. IOTN
2. Draker’s HLD index
3. Grainger’s treatment priority index.
4. Salzman’s handicapping malocclusion index
Treatment outcome indices.
– Assesssment of changes resulting from treatment
– Eg 1. PAR index
2. Summer’s index
Treatment complexity index
– ICON
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89. Various indices of Occlusion
Master and Frankel (1951)
– Count the number of teeth displaced or rotated
– Assessment of tooth displacement and rotation is
qualitative
Malalignment Index byVankrik and Pennel (1959)
– Tooth displacement and rotations were measured.
– Tooth displacement defined quantitatively : < 1. 5
mm or > 1. 5mm
– Tooth rotation defined quantitatively : < 45 degree
or > 45 degree
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90. Occlusal feature index by Poulton and
Aaronson (1961)
Measurement of
–
–
–
–
Anterior crowding
Cuspal interdigitation
Overbite
Overjet
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91. Handicapping Labio – Lingual deviation index
by Draker (1960)
Applicable only to permanent dentition.
The sagittal plane, FH plane and orbital plane
commonly used in orthodontics are basis for HLD
index.
Main aim is to find presence or absence and degree
of handicap caused by components of index.
All measurements are made with Boley gauge scaled
in mm.
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92. The 7 conditions of HLD index are
1.
2.
3.
4.
5.
6.
7.
Cleft palate
Traumatic deviations.
Overjet
Overbite
Mandibular protrusion
Open bite
Labio- Lingual spread
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93. Conditions observed
1.
2.
3.
4.
5.
6.
7.
8.
9.
HLD score
Cleft palate
Score 15
Severe Traumatic deviations
Score 15
Overjet in mm
Overbite in mm
Mandibular protrusion in mm
x5
Open bite in mm
x4
Ectopic eruption ,Anteriors only each tooth
x3
Anterior crowding : Maxilla
Anterior crowding : Mandible
TOTAL
A score of 13 and over constitutes a physical handicap.
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94. Handicapping Labio – Lingual deviation index
by Draker (1960)
Applicable only to permanent dentition.
The sagittal plane, FH plane and orbital plane
commonly used in orthodontics are basis for HLD
index.
Main aim is to find presence or absence and degree
of handicap caused by components of index.
All measurements are made with Boley gauge scaled
in mm.
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95. The 7 conditions of HLD index are
1.
2.
3.
4.
5.
6.
7.
Cleft palate
Traumatic deviations.
Overjet
Overbite
Mandibular protrusion
Open bite
Labio- Lingual spread
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96. Conditions observed
1.
2.
3.
4.
5.
6.
7.
8.
9.
HLD score
Cleft palate
Score 15
Severe Traumatic deviations
Score 15
Overjet in mm
Overbite in mm
Mandibular protrusion in mm
x5
Open bite in mm
x4
Ectopic eruption ,Anteriors only each tooth
x3
Anterior crowding : Maxilla
Anterior crowding : Mandible
TOTAL
A score of 13 and over constitutes a physical handicap.
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97. Occlusal index by Summers (1966)
Nine weighted and defined measurements –
1.
2.
3.
4.
5.
6.
7.
8.
9.
Molar relation
Over jet
Overbite
Posterior cross bite
Posterior open bite
Tooth displacement
Midline relation
Maxillary median diastema
Congenitally missing maxillary incisors.
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98. Seven malocclusion syndromes defined
1.
2.
3.
4.
5.
6.
7.
Overjet and open bite
Distal molar relation, overjet, overbite, posterior
crossbite, midline diastema and mid line deviation.
Congenitally missing maxillary incisors.
Tooth displacement. ( actual and Potential)
Posterior open bite.
Mesial molar relation, overjet, overbite, posterior
crossbite, midline diastema and mid line deviation.
Mesial molar relation, mixed dentition analysis
(potential tooth displacement) and tooth displacement.
Different scoring schemes and forms for different
stages of dental development: Deciduous, Mixed &
Permanent dentition.
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99. Treatment priority index by Grainger
(1967)
The precursor of the TPI was the Malocclusion Severity
Estimate (MSE) developed by Grainger at the
Burlington Orthodontic Research Center.4 in 1960-61
Unlike the TPI, the MSE score was that of the
syndrome with the largest value, regardless of the scores
of the other syndromes.
In the MSE the absence of occlusal disorders was not
scored as zero.
The TPI also differed from the MSE by deleting
potential tooth displacement (mixed-dentition space
analysis) and by rating distoclusion and mesioclusion
equally.
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100. Treatment priority index by Grainger (1967)
Malocclusion types –
Crowding /Malalignment problems
– Tooth displacement
–
–
–
Score 0 (ideal)
Score 1 – 5 (moderate)
Score > 5 ( severe)
Anteroposterior problems
–
–
Overjet 6 mm or more
Lower overjet 1mm or more
Vertical problems
–
–
Open bite 2mm or more
Over bite 6mm or more
Transverse problems
–
–
Lingual crossbite 2 or more teeth
Buccal crossbite 2 or more teeth
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101. TPI is based on a scale of
1.
2.
3.
4.
0 (near ideal occlusion)
1 - 3 ( mild malocclusion)
4 – 6 ( Moderate malocclusion)
Over 6 ( severe malocclusion)
TPI scores only occlusal characteristics, excluding
skeletal and facial components.
TPI is used in national studies of orthodontic needs
for children.
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102. Handicapping malocclusion assessment
records by Salzmann (1968)
1.
The purpose of HMAR – To establish priority for
treatment according to severity as shown by score.
Weighted measurements consists of 3 parts –
Intra arch deviations
Missing teeth
Crowding
Rotation
Spacing
1.
Interarch deviations
Overjet
Overbite
Crossbite
Openbite
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Mesiodistal deviations
102
103. Six handicapping dento-facial deformities
1.
2.
3.
4.
5.
6.
Facial and oral clefts
Lower lip palatal to maxillary incisors.
Occlusal interferences
Functional jaw limitations
Facial asymmetry
Speech impairment.
Score 8 points for each deviation.
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106. Index of Treatment Need (IOTN)
by Shaw
Index has two components1.
2.
Dental Health component – derived from occlusion
and alignment.
Aesthetic component – Derived from comparison of
dental appearance to standard photographs.
IOTN is usually calculated by direct examination, but
dental health component can be studied by dental
casts.
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107. A special ruler summarizes the information
needed for dental health component.
Assessed in order :
1. Missing teeth
2. Overjet
3. Crossbites
4. Displacements (Contact point)
5. Overbite
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110. Esthetic Index
Grades 8 – 10 =
definite need for
treatment.
5 – 7 = moderate/
borderline need
1 – 4 = No/ slight
need
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111. Peer assessment rating Index (PAR index)
Index of orthodontic treatment outcome
Developed by 10 experienced British orthodontists.
Its developed mainly to assess effectiveness of
Orthodontic treatment .
Assigns scores to different occlusal traits.
Study models used.
A scoring system was developed and a ruler designed
to allow analysis of a set of study casts in 2 minutes.
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112. 5 components-
Weighting
1. Upper & lower anterior segment - 1
2. Left and right buccal segments 1
3. Over jet
- 6
4. Overbite
- 2
5. Centerlines
- 4
Individual scores are summed to get a final score..
Index is applied to both the start and end of treatment
study casts, and change in total score reflects the success
of treatment.
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113.
1.
2.
Change expressed as:
Reduction in weighted PAR score : 22 point
reduction – Greatly improved
% reduction in weighted PAR score:
< 30% reduction – worse/ no better
> 30% reduction – Improved.
Indicator of clinical performance.
Can be insensitive and misjudge individual patient’s
needs.
Limitations of PAR
1. Generic weightings of Over jet and overbite.
2. Sensitive to malocclusion with high over jet.
3. Overbite low weighting.
4. Zero weighting for displacements.
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115. TheValidation of PAR for Malocclusion severity
and Treatment Difficulty
De Guzman,bahiraei, Vig, Weyant and O’Brien – AJO-DO 1995
11 American Orthodontists examined a sample of 200
sets of study casts and rated them for malocclusion
severity and perceived treatment difficulty.
The results of this study made it possible to derive a set
of weightings for the PAR index that would represent
groupings of malocclusion severity and treatment
difficulty, according to perceptions of panel of
Orthodontists.
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117. Index of Complexity Outcome and Need
(ICON)
Based on expert opinions of 97 orthodontists from
various countries.
For use on patients and Dental casts.
A single assessment method to record complexity,
outcome and need.
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118. 5 components taking about 1 min to measure.
1. Aesthetic component
10 pictures
1. Upper arch Crowding/ Spacing
Score according to amount of crowding or spacing
Impacted teeth in either arch immediately scored 5
Spacing in one part can cancel out crowding elsewhere.
1. Crossbite
2. Incisor open bite/ overbite
Open bite measured at mid incisal edges
Deep bite is measured at deepest part of overbite.
1. Buccal segment Antero posterior
Quality of buccal segment interdigitation is measured
(not Angles Classification)
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122. Goslon yardstick :A new system of assessing
dental arch relationships in childeren with UCLP – Michael
Mars, Dennis A. Plint : 1987 A cleft Palate journal
The Goslon ( Great Ormond Street, London and Oslo)
Yardstick is a clinical tool that allows categorization of
the dental relationships in the late mixed and or early
permanent dentition in to 5 discrete categories.
Objective : 1. To categorize malocclusions in patients
with UCLP to represent severity of malocclusion and the
difficulty of correcting it.
2. To compare long term results of different approaches
to the early treatment of children with UCLP.
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123.
1.
2.
3.
Development of Yardstick – Clinical features
considered most important in characterizing
malocclusion in children with UCLP are –
A- P arch relationship –Class III incisor relationship>
class II div I
Vertical labial segment relationship – Open bite>
Reduced overbite > deep overbite.
Transverse relationship – Canine crossbites > molar
crossbites.
To test the application of these subjective criteria
study models of 30 cases were taken.
These models were ranked by 4 orthodontists and
separated in 5 groups , which then formed basis for
yardstick.
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129. Group 1 – excellent
Group 2 – good
Group 3 – fair
Group 4 – poor
Group 5 – very poor
Group 1 or 2 - simple orthodontic treatment/ no
treatment
Group 3 – complex orthodontic treatment
Group 4 – limit of orthodontic treatment without
orthognathic surgery
Group 5 – Orthognathic surgery
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