1.
ORTHODONTIC
DIAGNOSIS

2.
INTRODUCTION
 Orthodontic diagnosis deals with
recognition of the various
characteristics of the malocclusion.
 Orthodontic diagnosis should be
based on scientific knowledge
combined at times with clinical
experience and common sense.
 diagnosis include case history,
clinical examination and other
diagnostic aids such as study casts,
radiographs and photographs.

3.
 Comprehensive orthodontic diagnosis is
established by clinical implementation
called diagnostic aids.
 Orthodontic diagnostic aids are of two
types namely’;
1. Essential diagnostic aids
2. Supplemental diagnostic aids

4.
ESSENTIAL
DIAGNOSTIC AIDS
They are clinical aids that are considered very
important for all cases.
The following are essential diagnostic aids;
1. Case history
2. Clinical examination
3. Study models
4. Certain radiographs;
 Periapical
 Bitewing
 Panoramic
5. Facial photographs

5.
Supplemental
diagnostic aids
 They are certain aids that are not essential in
all cases. They may require specialized
equipments that an average dentist may not
possess.
 The supplemental diagnostic aids include;
1-Specialized radiographs ex;
a-cephlometric radiographs
b-occlusal intra-oral films
c-selected lateral jaw views
d-cone shift technique
2.Electromyographic examination of muscle
activity

6.
3.Hand wrist radiographs to assess bone
age or maturation age
4.Endocrine tests
5.Estimation of basal metabolic rate
6.Diagnostic set-up
7.Occlusograms

7.
CASE HISTORY
 Case history involves eliciting and
recording of relevant information
from the patient and parent to aid
in overall diagnosis of the case
PERSONAL DETAILS:
NAME :the patient’s name should
be recorded for the purpose of
communication and identification.

8.
 AGE-the patients chronological age should be
recorded. Age consideration helps in diagnosis
as well as treatment planning.
 growth modification procedures using
functional and orthopaedic appliances are
carried out during growth period.
 SEX-patient’s sex should be recorded in case
history.
 This is important in planing treatment,as the
timing of growth events such as growth spurts
is different in males and females.

9.
 ADDRESS AND OCCUPATION-recording of
address and occupation helps in evaluation of
socio-economic status of the patient and the
parents.
 CHIEF COMPLIANT -the patient’s chief
compliant should be recorded in his/ her on
words.
 This help the clinician in identifying the priorities
and the desires of the patient.

10.
 MEDICAL HISTORY- full medical history is
recorded before orthodontic treatment.
 Few medical conditions contraindicate the
use of orthodontic appliances such as;
• Epilepsy
• History of blood dyscrasias
• Diabetic patient
• Rheumatic fever
• Cardiac anomalies
• Physically and mentally handicapped children

11.
 The medical history should include information
on drug usage.
 The use of certain drugs like aspirin may
impede orthodontic tooth movement.
 DENTAL HISTORY -it includes information on the
age of eruption of the deciduous and
permanent teeth,decay,history of extraction,
restoration and trauma to dentition.
 Past dental history helps in evaluation of
patient and parent’s attitude towards
treatment.

12.
 PRENATAL HISTORY-it include
information on the condition of the
mother during pregnancy and the type
of delivery.
 Forceps delivery predispose to TMJ
injuries that can result mandibular
growth retardation
 Drugs like thalidomide or affectation
with some infection during pregnancy
like german measles can results in
congenital deformities of child.

13.
 POST NATAL HISTORY -it includes
information on the type of feeding,
presence of habits and on the
milestones of normal development.
 FAMILY HISTORY- class 11,class111
malocclusions and congenital
conditions such as clefts of lip & palate
are inherited.
 Family history should record details of
malocclusion existing in other members
of the family.

14.
GENERAL EXAMIATION
 Height and weight-they provide clue
to the physical growth and maturation
of the patient.
 Gait-(way a person walks)
abnormalities of gait are usually
associated with neuromuscular
disorders that may have a dental
correlation.
 Posture-(way a person
stands)abnormal postures can
predispose to malocclusion due to
alteration in maxillo-mandibular
relationship.

15.
Body build-(physique)
 A)aesthetic-thin physique and narrow
dental arches.
 B)plethoric-obese with large square
dental arches
 C)athletic-normally built, neither thin nor
obese. normal sized dental arches.

16.
SHELDEON CLASSIFICATION
OF BODY BUILD
 A)ECTOMORPHIC-tall and thin
physique
 B) MESOMORPHIC-average
physique
 C)ENDOMORPHIC-short and
obese physique

17.
EXTRA ORAL EXAMINATION
SHAPE OF THE HEAD:
 A)MESOCEPHALIC-average shape
of the head. posses normal dental
arches
 B)DOLICOCEPHALIC-long and
narrow head . They have narrow
dental arches
 C)BRACHYCEPHALIC-broad and
short head. broad dental arches

18.
Mesocephalic,dolicocephalic,brachyce
phalic

19.
FACIAL FORM
A)MESOPROSOPIC-average or
normal face form
B)EURYPROSOPIC-face is broad
and short
C)LEPTOPROSOPIC-long and
narrow face form

20.
FACIAL SYMMETRY
 The patient’s facial symmetry is
examined to determine
disproportions of the face in
transverse and vertical planes. Gross
facial asymmetry can occur as a
result of:
 A. congenital defects
 B.hemi-facial atrophy/hypertrophy
 C.unilateral condylar ankylosis and
hyperplasia

21.
FACIAL PROFILE
 The facial profile is examined by viewing the
patient from the side. the facial profile helps in
diagnosing the gross deviation of maxillo-
mandibular relationship. the profile is assessed
by joining the following two reference lines.
1. A line joining the forehead and the soft tissue
point A(deepest point in curvature of upper
lip)
2. A line joining point A and the soft tissue
pogonion(most anterior part of the chin)

22.
 STRAIGHT PROFILE-the two lines form nearly
straight line.
 CONVEX PROFILE-the two lines form an angle
with concavity facing the tissue.
 This kind of profile occurs as a result of
prognathic maxilla retrognathic mandible as
seen in CLASS 11,DIVISON 1 MALOCCLUSION.
STRAIGHT PROFILE CONVEX
PROFILE

23.
 COCAVE PROFILE-the two reference lines form
an angle with convexity towards tissue.
 This type of profile is associated with a
prognathic mandible or retrognathic maxilla as
in CLASS 11 MALOCCLUSION.

24.
FACIAL DIVERGENCE
 Facial divergence is defined as anterior or
posterior inclination of the lower face relative to
the forehead.
 ANTERIOR DIVERGENT-a line drawn between the
forehead and the chin is inclined anteriorly
towards the chin..

25.
POSTERIOR DIVERGENT
 A line drawn between the forehead and chin slants
posteriorly towards chin.

26.
 STRAIGHT/ORTHOGNATHIC
 The line between the forehead and the chin is
straight or perpendicular to the floor.
 The facial divergence is to a large extend
influenced by patient’s ethnic and racial
background.

27.
ASSESSMENT OF ANTERO-
POSTERIOR JAW RELATIONSHIP
 It can be assessed clinically.
 Ideally maxillary skeletal base is 2-3 mm ahead of
the mandibular skeletal base when the teeth are
in occlusion.
 Estimation is done by placement of index and
middle fingers at the soft tissue point A and point
B respectively.

28.
 In skeletal CLASS11 PATIENTS, the index finger is
anterior to middle finger or the hand points
upwards.

29.
 In a skeletal CLASS 111 patient, the middle
finger is ahead of the forefinger or the hand
points downwards.

30.
 In a patient with CLASS 1 skeletal pattern the
hand is at an even level.

31.
ASSESSMENT OF VERTICAL SKELETAL
RELATIONSHIP
 The vertical skeletal relationship assessed by
studying the angle formed between the lower
border of the mandible and the Frankfort
horizontal plane(a line between the most superior
point of external auditory meatus and inferior
border of orbit)
 Normally the two planes intersects at the
occipital region.
 In case the two planes meets beyond the
occipital region, it indicates a low angle case or
a horizontal growing face.
 If two planes meet anterior to occipital region it
indicates a high angle case or a vertical growing
face.

32.
Assessment of vertical facial
height

33.
EVALUATION OF FACIAL
PROPORTIONS
 A WELL PROPORTIONED FACE CAN BE DIVIDED
INTO THREE EQUAL VERTICAL THIRDS USING
FOUR HORIZONTAL PLANES AT THE LEVEL OF THE
HAIRLINE,THE SUPRA ORBITAL RIDGE, THE BASE
OF THE NOSE AND THE INFERIOR BORDER OF
CHIN
 WITHIN THE LOWER FACE, THE UPPER LIP
OCCUPIES A THIRD OF THE DISTANCE WHILE
CHIN OCCUPIES THE REST OF THE SPACE.

34.
EXAMINATION OF LIPS
 The upper lip covers the entire labial surface of
upper anteriors except the incisal 2-3 mm
 The lower lip covers the entire labial surface of
lower anteriors and 2-3 mm of incisal edge of
upper anteriors.

35.
CLASSIFICATION OF LIPS
 COMPETENT LIP-THE LIPS ARE IN SLIGHT CONTACT
WHEN MUSCULATURE IS RELAXED.

36.
 INCOMPETENT LIPS-they are morphologically
short lips which do not form a lip seal in a
relaxed state.
 The lip seal can only be achieved by active
contraction of perioral and mentalis muscle.

37.
 POTENTIALLY INCOMPETENT LIP-they are normal
lips that fails to form a lip seal due to
proclaimed upper incisor.
 EVERTED LIP-they are hypertrophied lips with
weak muscular tonicity.

38.
EXAMINATION OF THE
NOSE
 The nose to a large extend contributes to the
esthetic appearance of a face.
 Nose size-normally the nose is one third of the
total facial height.
 Nasal contour-the shape of the nose can be
straight, convex or crooked as a result of nasal
in juries.
 Nostrils-they are oval and should be bilaterally
symmetrical. Stenosis of the nostrils may
indicate impaired nasal breathing

39.
EXAMINATION OF CHIN
 MENTOLABIAL SULCUS-concavity seen below the lower lip.
Deep mentolabial sulcus is seen in CLASS11,DIVISON 1
malocclusion.
 MENTALIS ACTIVITY-NORMALY MENTALIS IS NOT ACTIVE AT
REST.
 Hyperactive mentalis is seen in CLASS 11 DIVISON 1 CASES.
 CHIN POSITION AND PROMINENCE-prominent chin is usually
associated with class 111 malocclusion.
DEEP MENTOLABIAL SULCUS AND
HYPERACTIVE MENTALIS SEEN IN CLASS 11
DIVISON 1 MALOCCLUSION

40.
NASOLABIAL ANGLE
 It is the angle formed between lower border of
the nose and a line connecting the
intersection of nose and the upper lip with the
tip of the lip.
 This angle is normally 110 degree
 It reduces in patients with proclaimed upper
incisors prognathic maxilla.

41.
INTRA-ORAL EXAMINATION
EXAMINATION OF TONGUE
 ABNORMALITIES OF TONGUE CAN UPSET THE
MUSCLE BALANCE AND EQUILIBRIUM LEADING
TO MALOCCLUSION.
 A PATIENT WHOSE TONGUE CAN REACH THE TIP
OF THE NOSE IS SAID TO HAVE A LONG NOSE.
 THE LINGUAL FRENUM SHOULD BE EXAMINED
FOR TONGUE TIE

42.
EXAMINATION OF THE
PALATE
 Palate should be examined for the following
findings;
1. Dolicofacial patients have deep palate.
2. Presence of swellings in the palate
3. Mucosal ulcerations and indentations are a
feature of traumatic deep bite.
4. Presence of cleft in the palate.
5. The third rugae is usually in line with canines.
This is useful in the assessment of maxillary
anterior proclination.

43.
EXAMINATION OF GINGIVA
 GINGIVA SHOULD BE EXAMINED FOR
1. INFLAMMATION
2. RECESSION
3. MUCOGINGIVAL LESIONS
 POOR ORAL HYGEINE IS ASSOSIATED
WITH ANTERIOR MARGINAL GINGIVITIS.
 ANTERIOR GINGIVITIS COMMON IN
MOUTH BREATHERS DUE TO DRYNESS OF
MOUTH CAUSED BY OPEN LIP POSTURE.

44.
EXAMINATION OF FRENAL
ATTACHMENTS
 The maxillary labial frenum sometimes be thick
fibrous and attached relatively low.
 This may lead to midline diastema.
 Abnormal frenal attachment are diagnosed by
blench test.

45.
EXAMINATION OF TONSILS
AND ADENOIDS
 ABNORMALY INFLAMED TONSILS CAUSE
ALTERATIONS IN TONGUE AND JAW POSTURE THERE
BY UPSETTING THE ORO-FACIAL BALANCE LEADING
TO MALOCCLUSION

46.
ASSESSMENT OF
DENTITION;
Dental system is examined for ;
1. Teeth present in the oral cavity
2. Teeth unerupted
3. Teeth missing
4. Teeth erupted and not erupted
5. Presence of caries,restorations,malocclusions,hypoplasia,wear and
dislocation.
6. Check for the occlusion based on ANGLES CLASS 1, 11, 111
7. Record overbite overjet
8. Check for crossbite
9. Individual tooth irregularities such as rotation, displacement
,intrusion and extrusion are noted.
10. Check arch form

47.
FUNCTIONAL
EXAMINATION
 It is now established that normal function of
stomatognathic system promotes normal growth
and development of oro-facial complex.
 The functional examination should include the
following;
1. Assessment of postural rest position and inter
occlusal space.
2. Path of closure
3. Assessment of respiration
4. Assessment of TMJ
5. Examination of swallowing
6. Examination of speech

48.
ASSESSMENT OF POSTURAL REST
POSITION AND INTER-OCCLUSAL
CLEARANCE.
 The postural rest position of the mandible at which the
muscles that closes the jaw and those that open them are, in
state of minimal contraction to maintain the posture of
mandible.
 At postural rest position, a space exists between the upper and
lower jaws.
 This space is known as FREEWAY SPACE.
 FREEWAY SPACE is 3mm in canine region.

49.
Methods used to record the postural rest
position
PHONETIC METHOD; the patient is asked to repeat
some consonants “m or c’’ or repeat a word like
Mississippi.
 The mandible returns to postural rest position 1-2
seconds after the exercise.
 The patient is told not to change the jaw, lip or
tongue position after phonation, as the dentist
parts the lips to study interocclusal space.

50.
COMMAND METHOD
 THE PATIENT IS ASKED TO PERFOM CERTAIN
FUNCTIONS SUCH AS SWALLOWING.
 THE MANDIBLE TENDS TO RETURN TO REST POSITION
FOLLOWING THIS ACT.

51.
Non command method
 The patient is observed as he speaks or swallows.
The patient is no aware that he is being
examined.
 This is usually being carried out by talking about
topics unrelated to the patient while carefully
observing him or not

52.
Methods to measure inter-occlusal
clearance
 VERNIER CALIPERS CAN BE USED DIRECTLY IN
THE PATIENT’S MOUTH IN THE CANINE OR
INCISAL REGION TO MEASURE FREEWAY SPACE.
 THIS IS DIRECT INTRA ORAL METHOD.

53.
EVALUVATION OF PATH OF CLOSURE
The path of closure is the movement of mandible from the rest
position to habitual occlusion .
 Forward path of closure: a forward path of closure occurs in
patients with mild skeletal and prenormalcy or edge to edge
incisor contact. In such patients ,the mandible is guided to a
more forward position to allow the mandibular incisors to go
labial to the upper incisors.
 Backward path of closure: class 11 ,division 2 exhibit
premature incisor contact due to retroclined maxillary incisors.
Thus the mandible is guided posteriorly to establish occlusion
 Lateral path of closure : lateral deviation of mandible to left or
right side is associated with occlusal prematurities and a
narrow maxillary arch

54.
ASSESSMENT OF RESPIRATION
Humans may exhibit three types of breathing: nasal ,oral and
oro-nasal
Test to diagnose the mode of respiration:
 Mirror test : a double sided mirror is held between the nose
and the mouth .fogging on the nasal side of the mirror
indicates nasal breathing while fogging towards oral side
indicates oral breathing
 Cotton test : a butterfly shaped cotton piece is placed over
the upper lip below the the nostrils . if the cotton flutters down
indicates nasal breathing .this test is used to determine the
unilateral nasal blockage
 Water test: the patient is asked to fill his mouth with water and
retain it for a long period of time .while nasal breathers
accomplish this with ease , mouth breathers find it difficult
task.

55.
 Observation : in nasal breathers the external nares dilate
during inspiration .in mouth breathers ,there is either no
change in the external nares or they may constrict during
inspiration
EXAMINATION OF T.M.J.
The functional examination should routinely include
auscultation and palpation of temporomandibular joint
and musculature associated with mandibular opening.
The patient should be examined for the symptoms of
temperomandibular joint problems like clicking, crepitus ,
pain of masticatory muscles ,limitation of jaw movement ,
hyper-mobility and morphological abnormalities.
The maximum mouth opening is determined by measuring
the distance between the maxillary and mandibular
incisal edges with mouth wide open.
The normal inter incisal distance is 40- 45 mm

56.
EVALUVATION OF SWALLOWING
In a new born, tongue is relatively large and protrudes
between the gumpads and takes part in establishing
the lip seal .this kind of swallow is called infantile swallow
and is seen till one and half to two years of age .
Infantile swallow is replaced by mature swallow as the
buccal teeth start erupting. The persistence of infantile
swallowing can cause malocclusion .thus the swallowing
pattern of the individual should be examined.
The persistence of the infantile swallow is indicated by
the presence of the following features:
a. Protrusion of the tip of tongue
b. Contraction of perioral muscles during swallowing
c. No contact at the molar region during swallowing

57.
SPEECH
Certain malocclusions may cause
defects in speech due to interference
with the movement of tongue and lips
.this should be observed while talking
with the patient .
The patient can be asked to read
out from a book or asked to count
from 1-20 while observing the speech.
Patients having tongue thrust habit
tend to lisp while cleft palate patients
may have a nasal tone

58.
ORTHODONTIC STUDY MODELS
Orthodontic study models are accurate plaster reproductions of
teeth and their surrounding soft tissues .that are essential
diagnostic aid that make it possible to study the arrangement of
teeth and the occlusion from all directions .
Uses of study model include:
a) They enable study of occlusion from all aspect
b) Enable accurate measurements to be made in dental
arch.they help in the measurement of arch length, arch width
,and tooth size
c) Help in assessment of treatment progress by dentist as well as by
patient
d) Help in assessing the nature and severity of malocclusion
e) Helpful in motivation of patient and to explain the treatment
plan as weel as progress to patient and parents
f) Makes it possible to stimulate treatment procedures on cast
such as mock surgery
g) Useful to transfer records in case patient is treated by another
clinician

59.
ORTHODONTIC STUDY MODELS

60.
GNATHOSTATIC MODELS
They are orthodontic study models where the base of
the maxillary cast is trimmed to correspond to the
Frankfort horizontal plane.
DIAGNOSTIC SET UP
It was first propose by H.D. kesling
Diagnostic set up is made from an extra set of trimmed
and polished study models .the individual teeth and
their associated alveolar processes are sectioned off
and replaced on the model base in the desired
positions .the diagnostic set up thus help in simulating
the various tooth movement s that are planned for
patients

61.
USES OF DIAGNOSTIC SET UP
1. Useful in visualizing and testing the effect of
complex tooth movements and extractions on the
occlusion
2. Patient can be motivated by simulating the various
corrective procedures in the cast
3. Tooth size- arch length discrepancies can be
visualized
PROCEDURE
 The cast is cut using a fretsaw blade to separate
the individual teeth.
 A horizontal cut is made 3mm apical to gingival
margin
 Vertical cuts are made to separate the individual
teeth
 The individual teeth are set in desired position
using a red wax

62.
SUPPLEMENTAL
DIAGNOSTIC AIDS

63.
FACIAL PHOTOGRAPHS AS A DIAGNOSTIC AID
 Facial photographs offers a lot of information on the soft tissue
morphology and facial expression.
 Both extra-oral as well as intra- oral photographs are useful
diagnostic aids.
 Three extra-oral views are routinely taken:
a. Frontal view
b. Profile view
c. Oblique facial view
Extra-oral photograph are taken by positioning the patient in
such a manner that the F.H.plane is parallel to the floor
 The intr-oral photograph taken include:
a. Left and right lateral view.
b. Frontal view.
c. Maxillary and mandibular occlusal view.

64.
USES OF PHOTOGRAPHS
1. Useful in assessment of facial symmetry ,facial
type and profile
2. Serve as a diagnostic records
3. Help in assessing the progress of the
treatment

65.
ELECTROMYOGRAPHY
Electromyography is a procedure used for
recording the electrical activity of muscles the
resting potential of a muscle fiber is 85-90mV
Electromyograph is a machine used to receive ,
amplify and record the action potential during
muscle activity . Electromyogram is a record
obtained by such procedure . The action potential
picked up by the electrodes are of two types
Needle electrodes: used when muscles are placed
deep inside e.g. pterygoid muscle
Surface electrodes :used when muscle is superficially
placed just below the skin
Having picked up the action potential with surface or
needle electrodes it is recorded either with the
help of a moving pen in form of a graph or
recorded in form o f sound with help of a magnetic
tape recorder

66.
 Electromyography is used to detect abnormal muscle activity
associated with certain forms of malocclusion
a. In severe classII ,division1 malocclusion the upper lip is hypo-
funuctionl.Thus during swallowing ,the lower lip extends
upwards and forwards to place to force the maxilla labially
and a strong mentalis activity is seen .E.M.G .can be used to
study such a condition
b. Abnormal buccinator activity in classII ,division1
c. Overclosure of jaw is associated with accentuated
temporalis muscle activity
d. Children with cerebral palsy
e. E.M.G . Can be carried out after orthodontic therapy to see if
muscle balance is achieved

67.
RADIOGRAPHS USED IN
ORTHODONTIC DIAGNOSIS
 Radiograph routinely used for diagnosis in
orthodontic s are classified into two groups
1. Intra-oral radiograph
2. Extra-oral radiograph

68.
Intra –oral periapical
radiographs(I.O.P.A)
 They are radiographs that are used to view the
teeth and their supporting structures.
 Two intra oral techniques are used for
periapical radiography. The are;
 PARELLEING TECHNIQUE
 BISECTING ANGLE TECHNIQUE
USES
 To confirm presence or absence of teeth
 To establish presence or absence of supernumerary teeth
 Extend of calcification and root formation of teeth
 To study alveolar bone & PDL
 To determine size and shape of unerupted teeth
 To assess axial inclination of roots

69.
disadvantages
 Assessment of entire dentition requires too
many radiographs.
 They cannot be used in patients with high gag
reflex and trismus
Advantages
 Low radiation dose
 Excellent clarity of teeth and their supporting
structure
 Possible to obtain localized view of area of
interest.

70.
BITEWING
RADIOGRAPHS
 It records the coronal part of upper and lower
dentition along with their supporting structure.
1. Used to detect proximal caries
2. Height and contour of inter alveolar bone
3. To detect periodontal changes
4. To detect secondary caries below restorations.
5. To determine inter proximal calculus

71.
OCCLUSAL RADIOGRAPHS
 Occlusal radiographs are used in patients who
are unable to open their mouth wide enough for
periapical radiographs.
Uses
1. To locate impacted or unerupted teeth
2. To locate supernumerary teeth
3. To locate foreign bodies in the jaw
4. To diagnose the presence and extend of fractures

72.
EXTRA-ORAL
RADIOGRAPHS
 THEY ARE USEFUL WHEN LARGE AREAS OF FACE AND
SKULL ARE TO BE VISUALIZED
 PANORAMIC RADIOGRAPH
 It enables viewing of both maxillary and mandibular
arches with their supporting structures
 USES:
 Studying deciduous root resorption and root
development of permanent teeth
 To study the path of eruption of the teeth
 Used to view ankylosed and impacted teeth
 To diagnose presence and extend of pathology and
fractures of jaw

73.
 ADVANTAGES
 Broad anatomic area can be visualized
 Radiation exposure is low
 Can be used in patient who are unable to
tolerate intra oral films or unable to open
the mouth
 DISADVANTAGES
 Expensive equipment
 Inclination of anterior teeth cannot be
visualized
 Less clear images as in periapical films
 Distortion, magnification and overlapping
of the structures occur

74.
CEPHALOMETRIC
RADIOGRAPHS
 Specialized skull radiograph in which the head is
positioned in a specially designed head holder
cephalostat.
 It is of two types
1. Lateral cephalogram
2. Postero-anterior cephalogram

75.
OTHER RADIOGRAPHS
 HAND-WRIST RADIOGRAPH
Radiograph of hand and wrist are useful in estimating the
skeletal age of a person .the hand and wrist region
have number of small bones whose appearance and
progress of ossification occur in a predictable
sequence. This enables skeletal age of a person they
are useful in assessing growth for planning growth
modification procedures and surgical resective
procedures

76.
RECENT ADVANCES in
diagnostic aids
 Some of the recently evolved diagnostic aids are :
 XERO RADIOGRAPHY
 it was invented by Chester f Carlson in 1937
 It’s a completely dry non chemical process which
makes use of electrostatic process as in Xerox
machines
 Xerox radiography makes use of a aluminium plate
that is coated with layer of vitreous selenium
 The selenium particles are given a uniform
electrostatic charge
 The charge plate is placed in a light tight, air tight
cassette

77.
 When the film is exposed it causes a selective
discharge of selenium depending up on the amount
of radiation used and relative density of objects
 This pattern of electric discharge on the plate is called
latent image
 The latent image is converted into visible image by a
process called development in a unit called processor
 the plate is exposed to charged particle called toner
 This particles adhere to the charged areas in amounts
proportional to the quantity of the charge present
 the image is now transferred on to a special kind of
paper called Xerox opaque paper
 The unique feature of xero radiography is that its
possible to have both positive and negative image
 Once latent image is converted into real image on to a
paper. The selenium plates can be discharged
cleaned and used again.

78.
Difference of xero radiographic image from
conventional radiographic image.
I. Exhibit high edge contrast due to a
phenomenon called edge enhancement
II. No special illumination is needed for viewing
of Xerox radiographic image
III. Choice of negative or positive image is
possible
Advantages of Xerox radiographic are:
I. Reduction in exposure time
II. Ease in manipulation
III. Ease of viewing
IV. edge enhancement effect
V. Cephalometric landmarks are easily identified

79.
 DIGI GRAPH
 It enables clinician to perform non invasive
and non radiographic cephalometric
analysis.
 Features of digi graph system includes
I. A landmark can be identified as a point in
3d
II. A cephalometric analysis can be made
independently of head position
III. Parallelism of x ray in mid sagittal plane
and symmetry of anatomic morphology
between left and right side is not
necessary.
digi graph allows all patients model
radiographs, photographs cephalograms
and tracing to be stored on one small disk-
reducing storage requirements

80.
MRI magnetic resonance
imaging
 MRI makes use of two fundamental properties of proton ie
spin and small magnetic movement
 The proton of hydrogen ion which is in water is utilized in
MRI
 The proton behave like small spinning magnets and when
placed in a magnetic field they tend to move parallel to
the field.
 Because of the spin the proton differently within their axis
progressing about the direction of the magnetic field.
 If a coil is now wound around a volume of protons ,they
now progress at 90 degree around the magnetic field at
the same frequency and induce a minute current in the
coil which when amplified can be displayed over a
oscilloscope this energy is utilized in scanning procedure

81.
Advantages of MRI
1. MRI does not have hazards as it uses non
ionising electromagnetic radiation
2. Anatomical details are as good as in ct scan
3. Greater tissue characterisation is possible
4. Imaging of blood vessel, blood flow,
visualisation of thrombus is possible
Disadvantages of MRI
1. Time taken is more
2. Not used in patients with cardiac pacemaker
3. Non visualisation of bone makes it useless in
bony lesions

82.
tomography
 Tomography can be used to visualize a section or a
slice of the object and there by eliminate undesirable
overlap.
 Tomographic can be conventional or computed
tomography.
 Conventional tomography :
 this is process by which a layer of a image with in the
body is produced while the images of structure above
and below that layer are made invisible by blurring.
 Blurring of the image outside the plane of interest is
accomplished by simultaneous movement of x ray
tube and film during the exposure.
 The tube and the film are connected so that
movements occur around a point or fulcrum
 As the distance from the point of rotation increases ,
amount of image blurring also increases

83.
 As the angle between the source/ film and tissue
increases thickness of the image is reduced
 Principles of tomography can be mechanically
implemented in two ways ;
 The x ray tube and film can move synchronously
in opposite direction in parallel planes
The x ray tube and film can move synchronously
and in opposite direction in parallel planes but
with motions other than straight lines that is
circular spiral etc
Computed tomography
 this is also called CT or CAT (computed axial
tomography)
 Ct systems are mainly complex imaging systems
which use thin beams of x ray that moves in
asynchronous manner with an array of detectors
which calculates and attenuate the x ray beam
at different angles and in different planes
 This data is spread in to computer which perform
numerous calculations as per the program and
constructs accurate image in the coronal axial
plane

84.
Advantages of ct scan
 Accurate visualization
 Computer programming makes to view
images in different shapes and densities.
Occlusograms
it is a tracing of photograph or a photocopy of
a dental arch . Occlusograms are used for the
following purposes:
to estimate occlusal relationships
To estimate arch length and width
To estimate the tooth movements required in all 3
planes of space
To estimate anchorage requirements

85.
 Occlusograms can be obtained in two ways
 the occlusal surfaces of the upper and lower
dental casts are photographed in a 1:1 ratio
and a tracing of the photograph is made.
 The cast are photocopied on a Xerox
machine and the occlusal photocopy is used
to obtain a tracing
Digital subtraction radiography
 comparatively this decrease the amount of
distracting background information and by
allowing the eye to focus on the actual
change that has occurred between two
images.
 technically this is a image enhancement
method that remove the structured noise from
the images.

86.
 Laser holography
 Holography is photographic technique for
recording and reconstructing images in such
way that 3d aspect object can be obtain
recorded image is called hologram
 Laser is light amplification by stimulated emission
of radiation
 Holography is a wave front reconstruction
process in which two coherent beams converge
to produce a constructive and distractive
interference pattern which is recorded on film
 orthodontic applications of laser holography:
 Storage of study model images
 Measurement of incisor intrusion
 To determine the centers of rotation produced
by orthodontic process
 Lower incisor space analysis
 to access facial and dental arch symmetry

87.
photocephalometry
 Thomas in 1978 developed
photocephalometry to better visualize soft
tissues of patient
 three radiopaque metallic markers with holes
are placed on patients skin with adhesives
and standard lateral and anterior posterior
cephlograms are taken
 Using the same position lateral and frontal
photographs are taken
 the photographs are printed to same size as
the radiographs and are superimposed over
the radiographic tracing taking the metallic
markers as the guide

88.
cineradiography
 Basically radiographic motion picture
 The subject is oriented properly and stabilized in
modified cephalostat
 an x ray motion picture is obtained using a cine
camera which runs at 240 frames per sec
 it is used to visualize swallowing pattern of patient
 The x ray motion picture is studied using a movie
projector

89.
Thank you