ortho-lec3-Diagnostic aids of orthodontics

1. 1
Orthodontic diagnosis
DIAGNOSTIC AIDS
Diagnostic aids include the useof:
1. Study models
2. Orthopantomography
3. Cephalometries
4. Other views: hand wristand periapical radiographs
5. Photography
6. 3D Imaging
Orthopantomographs:
Exactly after Second World War, Paatero of Finland tumed to body section
radiography or tomography (laminagraphy) for better radiographic visualization of
craniofacial structures.It is possible to obtain radiographic image of a particular area, or
a layer within 3 dimensional subjects by carefully synchronizing the movement of the
source of radiation and the film. With both the x-ray beam source and the film casseette
rotating, everything else is thrown out of focus except the precise level of structures of
interest. The parts that in focus will appear in sharp details; while, the intervening
structures are blurred out.
The benefits in brief:
*-Razor-sharp real-timeimages, no film processing, no scanning, no readouts.
*-Environmental protection, no darkroomno chemicals
*-Radiation dosereduction ranging from50%(panoramic)to 70%( cephalometric)
*-Within 2 minutes it appears on the monitor & ready to be analyzed or stored on p.c.or
you can send it throw E-MaiL p.c.
‫طعمة‬ ‫د.رؤوف‬

2. 2
Several advantages from the OPG can be obtained:
1- Comfort, since no film will be inserted inside the patient mouth. And the total time
needed not exceed 1-1.2 min to performthe x-ray.
2- It is more easy for the operator when he has uncoopertivepatients, children patient
with gagging reflex & trismus = lockjaw.
3- Least total radiation " 5.06 rad " in comparison with periapical x-ray.
Disadvantages:
1- It cannotgive precise information on periodontal membrane.
Note: the intraoral radiograph provides more accurate information about the
periodontal ligament.
2- The lower incisors region is not properly reproduced due to some overlapping as a
result of shifting in the axis of rotation.
3 - Additionally the inclination of the lower incisors is usually slanted with the crown
mesially inclined.
Uses of OPG:
1- For growth & development studies: Delayed tooth eruption, abnormality in eruption
path, abnormal resorption, supernumerary teeth, cysts, congenitally absent teeth,
ankylosis, prolong retention, density of the bone, axial inclination, inadequate space of
the clinical entities that concerning to the general practitioner or orthodontist. & distant
from apices to mandibular plane.
2- The tempromandibular joint: the OPG provides a sharp & accurateprofile view of the
condyle & the articular eminence or the articulm fosseitself.

3. 3
3- Sinuses & mastoid region: the importance of maxillary sinuses is very recognized by
orthodontist since a reduced sinuses size related to mouth breather & collapse of
maxillary segments.
4- Mandibular morphology: the OPG gives a clear picture about the bony mass of the
mandible, the extent of the alveolar bone, height & width of the ramous. "All of these
information are important in regards of orthodontic treatment" good survey for the
teeth present & absent is clear in addition to the presence of any supernumerary teeth
or any pathology.
5- Space adequacy: the OPG of grate benefit during the serial extraction procedure
which require the removal of some deciduous teeth followed by some permanent teeth
(usually the fours) and this require knowledge about the stages of root formation of the
teeth.
6- Investigation of facial asymmetries and swelling.
7- Suspected fractures of mandible and maxilla.
Study models
Dental casts for orthodontic purposes are usually trimmed, so that the bases
assumed in a symmetrical shape & then they are polished. This trimming will aid to
detect the asymmetry within the dental arches & to analyze arch form. The trimmed &
polished study model is acceptable for presentation to the patient. The study model
provide a good help to examine the teeth from facial and lingual aspect during
articulation, In addition to the possibility of the space analysis on the study model & the
size selection of the orthodontic bands.
Finally: the study model used for modulation due to treatment & the explanation of that
for the patient or parents.

4. 4
In fixed appliance therapy: the study model can be used to formand bend the arch wire,
which will fit exactly to the arch form of the patient.
Steps of fabrication study model:

5. 5

6. 6

7. 7
Space analysis (Carey's analysis)
The arch length-tooth material discrepancy is the main cause for most
malocclusions. This discrepancy can be calculated with the help of Carey's analysis. This
analysis is usually done in the lower arch. The same analysis when carried out in the
upper arch is called as arch perimeter analysis.
Methodology
Determination of arch length: The arch length is measured anterior to the first
permanent molar using a soft brass wire. The wire is placed touching the mesial aspect
of lower first permanentmolar, then passed along the buccal cusps of premolars, incisal
edges of the anteriors and finally continued the same way up to the mesial of the first
molar of the contralateral side. The brass wire should be passed along the cingulum of
anterior teeth if anteriors are proclined and along the labial surface if anteriors are
retroclined. The mesiodistal width of teeth anterior to the first molars are measured and
summed up as the Total tooth material. The difference between the arch length and the
actual measured tooth material gives the discrepancy.
Interpretation
The amount of discrepancy between arch length and tooth material is calculated.
If the arch length discrepancy is:
• 0 to 2.5 mm-Proximal stripping can be carried out to reduce the minimal tooth
material excess.
• 2.5 to 5 mm-Extraction of 2nd premolar is indicated
• Greater than 5 mm-Extraction of first premolar is usually required.

8. 8

9. 9
INTRAORAL RADIOGRAPHS
The intraoral radiographs are the easiest to take for most orthodontic patients.
The most frequently used views include:
A. Intraoralperiapicalradiographs
B. Bitewing radiographs
C. Occlusalradiographs
A. IntraoralPeriapicalRadiographs
They are ideal for the detection of anomalies related to changes in tooth
structure and/ or the lamina dura and/ or the periapical region. They are ideal for
localized views in relatively small areas of interest because of the excellent clarity that
they allow.
They are recommended for:
1. Adult cases with periodontal disease
2. Evaluation of the dental health of the deciduous and/or permanent teeth periapically
3. Detection of pathologic conditions in the early stage especially dental caries
4. Assessment of traumatized teeth after an injury (especially root fractures)
5. Calculation of the total space analysis
6. Detection of root resorption, before during and after treatment.
B. Bitewing Radiographs
Bitewing radiographs are used primarily to record the coronal portion of the
upper and the lower posterior dentition. They are used for:
• The detection of proximal caries
• The study of interdental bone height
• The detection of secondary caries under restorations

10. 10
•The detection of overhanging margins of proximal restorations.
C. Intraoral Occlusal Radiographs
They are useful in localization of impacted teeth or for the study of the labio-
lingual position of the root apices in the anterior segments of the upper and the lower
dentition.
FACIAL PHOTOGRAPHS
Facial photographs are the easiest to store, occupy the least amount of space and
provideimmense information to the clinician as well as the patient. Photographs can be:
• Extraoral photographs
• Intraoral photographs
 Extraoral Photographs
Extraoral photographs are considered essential records and should be taken before
starting treatment and after completion of treatment. The information provided by
these photographs is valuable to the orthodontist and patient.
Uses of extraoral photographs
1. Evaluation of craniofacial relationships and proportions before and after treatment
2. Assessment of soft tissue profile
3. Detection and recording muscle imbalances
4. Detecting and recording facial asymmetry
5. Identifying patients
The requirements for extraoral photographs include:
1. High quality and standardized facial photographs taken in natural head position

11. 11
2. Patients head oriented accurately in all three planes of space and in FH plane
3. Background free of distractions
4. Quality lightening revealing facial contours with no shadows in the background
5. Ears exposed for purpose of orientation
6. Eyes open and looking straight ahead with glasses removed
The views taken regularly for patients include:
1. Frontal facial with lips relaxed
2. Facial profile with lips relaxed
3. Three-quarter view, smiling
4. Frontal facial smiling.
For facial deformity cases or cases likely to undergo orthognathic correction, further
views are required:
1. Frontal facial in maximum intercuspal position, lips sealed
2. Left and right, facial profile in maximum intercuspation, lips sealed
3. Left and right, facial profile, lips relaxed
4. Left and right three-quarter view, smiling
5. Bird view from above the patient (by standing behind and above the patient)
Intraoral Photographs
These views are used in:
1. Recording the structure and color of enamel
2. Patient motivation
3. Assessing and recording health or disease of the teeth and soft tissue structures
4. Monitoring of treatment progress

12. 12
5. Studying of relationships before, immediately following and several years after
treatment, to improve treatment planning
The requirements for intraoral photographs include:
1. High quality and standardized intraoral color prints
2. Photographs should be oriented accurately in all three planes of the space
3. Free of distractions - retractors, labels etc.
4. Quality lightening revealing anatomical contours and free of shadows
5. Tongue should be retracted posteriorly
6. Free of saliva and/or bubbles
7. Clean dentition
The views include:
1. One frontal photograph in maximum intercuspation
2. Two lateral views-right and left
3. Two occlusal views-upper and lower
3D IMAGING
Except for a few structures of interest which lie in the midsagittal plane, it is
difficult to make accurate measurements using cephalograms. Conventional facial
photos too lose depth information by projecting images of structures at different
heights upon a single plane. Moreover, the dental cast (a three dimensional
representation of oral tissues) must be integrated into facial images.
Conventional computed tomography (CT) imaging involves' the use of rotating X-ray
equipment, combined with a digital computer, to obtain images of the body. Using CT
imaging, cross-sectional images of body organs and tissues can be produced.
Their use in orthodontic treatment has been limited due to the following reasons:

13. 13
1. The dose of ionizing radiation has been high
2. Economically costly
3. Slices of relatively thick
4. Distortions are produced if CT scans are done with orthodontic appliances in place
Cone beam computed tomography (CBCT)
CBCT is a faster, more compact version of traditional CT with a lower dose of
radiation. Through the use of a cone-shaped X-ray beam, the size of the scanner,
radiation dosage and time needed for scanning are all dramatically reduced.
The 3D views produced may be useful in certain orthodontic cases:
1. Accurate location of impacted teeth and a more accurate assessment of any
associated pathology, particularly resorption of adjacent teeth.
2. Assessment of alveolar bone coverage
3. Assessment of alveolar bone height and volume {which may be relevant in potential
implant cases)
4. Study the placement of microimplants (used to provide anchorage)
5. TMJ or airway analysis
CBCT allows the acquisition of detailed 3D images of the face in high resolution. Using
this virtual 3D information, computer-aided surgery (CAS) software allows surgical
planning and simulation which offers a number of possibilities:
1. A more detailed vision of the anatomy of the patient in three dimensions.
2. The data from CBCT can be combined with the data captured from 3D facial camera
systems. This allows the clinicians to see the relationship of the soft tissues with the
underlying hard tissues. Virtual surgery can then be undertaken on this 3D model and
the effect on the overlying soft tissues assessed.

14. 14
3. Virtual surgery will allow the surgeon to calculate the most appropriate and safest
osteotomy lines in advance of the operation.
4. This virtual setup can be used to manufacture positioning splints and construct
customized fixation plates. Although the radiation dose is considerably smaller than
conventional CT scanning, the dose is still higher than for the conventional radiographs.
Therefore, CBCT should therefore only be used when conventional radiography has
failed to give or is very unlikely to give, the necessary diagnostic information. Other 3D
imaging techniques are also being developed for use in orthodontics such as optical
laser scanning and stereo-photogrammetry.