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1. RADIOGRAPHS IN PROSTHODONTICS
Introduction
Dental radiographs are a necessary component of comprehensive patient
care.In dentistry, radiographs enable the dental professional to identify many
condition that may otherwise go undetected clinically. Detection is one of
the most important uses of dentistry used radiographs. Many dental diseases
and conditions produce no clinical signs or symptoms and are typically
discovered only through use of dental radiographs.
Uses of dental radiographs:
1. To detect lesions, disease and conditions of teeth and surrounding
structures that cannot be identified clinically.
2. To confirm and classify or foreign objects.
3. To localize lesions or foreign objects.
4. To provide information during dental procedures.
5. T o evaluate growth and development.
6. To illustrate changes secondary to caries, periodontal disease and
trauma.
7. To document the condition of patient at a specific point of time.
The history of dental radiography begins with discovery of X-rays.
WILHELM CONRAD ROENTGEN (pronounced ‘ren-ken’), a
Bavarian physicst discovered X-ray on Nov 8,1895.This monumental
discovery revolutionized the diagnostic capabilities of medical and
dental profession and a result, forever changed the practice of medicine
and dentistry.
Roentgen named his discovery X-rays, the “X” referring to unknown
nature and properties of such rays.He published a total of three scientific
papers detailing the discovery, properties and characteristics of X-rays.
During his life time, Roentgen was awarded many honours and
distinctions including first noble prize ever awarded in Physics. For a
number of years after discovery, X-rays were referred to as Roentgen
rays, Radiology as Roentgenology and Radiographs were named
Roentgenography.

2. Pioneers in dental X-ray radiation:
Following the discovery of X-rays in 1895, a number of pioneers helped
to shape the history of dental radiography. After announcement of
discovery of X-rays in 1985, a German dentist OTTO WALKHOFF
made first dental radiograph.
C.Edmund Kells, a new Orleans dentist is credited with the use of
radiographs dentistry in 1896. Kells dedicated to the development of Xrays ultimately cost him his fingers , later his hand and his arm.
Other pioneer in dental radiography include William H.Rollins, a
Boston dentist who first developed X ray unit.
Frank Van Woert, a dentist from Newyork city was the first to use film
in intraoral radiography.
Howarth Riley Raper, an I ndiana uiversity professor established the
first college course of radiography for dental students. Likewise dental
x-ray film, dental radiographic techniques were developed.
Present day diagnosis, treatment planning and evaluation of prognosis in
the field of medicine and dentistry depends a lot on radiographic
imaging and prosthodontics is no way exception to his principle. Though
use of various radiographs was limited for evaluation and to reach a
conclusion regarding diagnosis and treatment planning previously in
Prosthodontics, present day radiographs are used to analyse even the
prognosis or treatment outcome especially after advent of advanced
Prosthodontic care by Implants and Maxillofacial prosthesis.

3. COMPLETE DENTURES
Radiographic evaluation
Radiographs are important aids in the evaluation of submucosal conditions
in patients seeking prosthodontic care. The presence of abnormalities in
edentulous jaws may be unsuspected because of absence of any clinical
signs or symptoms they show the relative thickness of alveolar ridge and the
mucoperiosteum, the quality of the bone.
Extraoral radiographs can provide survey of the patient’s denture
foundation and surrounding structures. Panoramic dental radiograph are
readily available for convenient examination of edentulous patients.
Knowledge of location of the anatomic structures is an essential prerequisite in the evaluation of the radiographs.
Intraoral radiographs have limited role in edentulous patients. They can
used in locating any localized abnormality or the examination of
tuberosities.
The transition from emulsion based film radiography to photostimuable
phosphor based films CCD (charge couple devices) and CMOS
(complementary metal oxide semiconductor) are well under way. This is
limiting the exposure of patients to radiations.
Other investigations tools these include Tomography, Zonography,
Computed Tomography, Magnetic Resonance, Radionuclide Imaging and
Ultrasounds.
Radiographs in complete dentures should rule out foreign bodies, retained
root tips, unerupted teeth or various pathoses of developmental,
inflammatory or neoplastic origin.

4. Cephalometric and temporomandibular joint radiography are
performed to rule out relevant abnormalities for complete
denture prosthesis functioning and maintenance.
Radiographs are usually taken to find out the presence of
hidden abnormalities, to note the structure of cortical bone
and trabeculae, sharp projections, thickness of soft tissue etc.,
Retained roots with no apparent pathology can often be left
alone provided the patient is informed of their presence and
X-rayed periodically.
The interpretation of panoromic radiographs follow a 5 step
analysis as outlined by Chemenko.
The panoromic is also an aid in documenting the amount of
ridge resorption. A very useful system of classifying the
amount of ridge resorption was described by WICAL &
SWOOPE .They found that the lower edge of mental
foramena divides the mandible into thirds in normal dentulous
panaromic radiograph. If the distance is measured from
inferior border of mandible to inferior margin of mental
foramina and then multiplied by 3 , the resultant product is a
reliable estimate of original alveolar ridge crest height.
Amount of ridge resorption can be calculated an classified as
Class I (MILD RESORPTION)Loss upto 1/3 of original
vertical height
Class II (MODERATE RESORPTION) Loss upto 1/3 to 2/3 of vertical
height.
Class III (SEVERE RESOPTION) Loss of 2/3 or more of vertical
height.
To conclude periapical survey of edentulous jaws are acceptable but
Panaromic radiographs are faster reduce patient exposure to radiation
and image the entire maxilla and mandible.

5. REMOVABLE PARTIAL DENTURES
Planning
A panoramic radiograph is of great diagnostic value and
should be made wherever possible.
Periapical radiographs of the remaining teeth may also be
required is order to supplement the OPG.
 teeth with questionable prognosis
 Requiring surgical & Endodontic restoration
In case OPG not there then a full month service of IOPAS have
to be there.
The diagnostic factors or criteria judged are.
(i) Carious lesion
 initial carious lesions
 Recurrent caries adjacent to existing restorations
 Deep lesions or extensive restorations on potential abutment
teeth.
 Obvious indications for endodontic therapy cast restorations
are noted.
(ii) Root Length, Size & Form
 Large, longer roots are more favorable abutment teeth.
 Form of the root is equally important tapered or conical roots
are unfavorable because ever a small loss of bone height can
greatly diminish the attachment area.
 Multirooted teeth with divergent and curved roots are better
than single rooted or Multirooted with fused roots.
 Position of roots of adjacent tooth is also important, in case
the roots are close with little interproximal bone separating
them even a moderate irritation of force may be destructive.
Crown root ratio
The relationship of the length of the clinical area and the
amount of root embedded is bone is a very critical factor. If the
crown root ratio is greater than 1:1 then the tooth has a poor
prognosis as an abutment. It is also poor when there is furcation
involvement of a multi rooted teeth is present.

6. Lamina dura or periodontal space
 The width of the periodontal ligament space is of significance
in evaluating the stability of the teeth. A thin uniform
ligament space and an uninterrupted Lamina dura is a more
favorable sign compared to a more widened or irregular space.
 A thickening of the lamina dura may occur if the tooth is
mobile, has occlusal trauma or is under heavy functions
occlusal trauma can cause partial or total loss of the lamina
dura.
 Partial or total absence of the lamina dura may be found in
systemic disorders such as Hyperparathyroid and Paget’s
disease.
Systemic disease must be considered whenever this
condition is noted; Destruction forces or the disease processes
causing changes in the lamina dura must be correlated or the
abutment tooth will have a poor prognosis.
Bone quality & quantity
Bones which has small closely grouped trabecular and small
inter trabecular spaces is considered well mineralized; hence
strong & healthy.
This is portrayed in the radiograph as relatively radiopaque,
although a certain amount of variation is size of the trabeculae is
normal and to be expected.
Bone height of quantity
In this evaluation care must be taken to avoid any
interpretation errors resulting from angulations factors with is
normally used in the short cone or Bisecting angle technique.
As a result of the central ray using shot at an angle results
in the buccal bone to be projected higher on the crown than the
lingual or palatal bone.
Therefore when interpreting bone height it is imperative to
follow the line of the lamina dura from the apex towards the
crown of the tooth until the opacity of the lamina materially
decreases.
At this point of opacity charge, a less dense bone extends
further towards the tooth crown.

7. This additional amount of bone represents false bone
height. Thus the true height of the bone is ordinarily where the
lamina shines a mark decrease in opacity.
At this point the trabecular pattern of the bone
superimposed on the tooth root is lost. And the portion of the
root b/w the CEJ and the true bone height has the appearance
being base as devoid of covering.
BONE INDEX AREAS
Index areas are those areas of alveolar support that disclose
the reaction of bone to additional stress.
There might be a positive Bone factor or a Negative Bone
factor depending on the response of the alveolar bone to
additional loading.
A position or a favorable response
A decrease in the trabecular pattern (bone condensation))
A heavy cortical layer.
Dense lamina dura
Normal bone height
Normal periodontal ligament space.
Retrograde or negative response
 loss of lamina dura
 decrease bone height
 widening of periodontal ligament space
 apical and furcation radioluscency
Teeth that have been subjected to greater than normal stress and
provide good index information are:(i) Abutment teeth of an FPD or RPD.
(ii) Teeth involved in occlusal interferences.
(iii) Teeth receiving greater occlusal stress due to
loss of adjacent teeth.
(iv) Tipped teeth with occlusal contact.
Radioluscent or radioopaque lesions.
 The presence of cysts, accesses, embedded teeth or roots or
foreign bodies must be noted.
 A surgical diagnosis and treatment must be planned so that a
conditions does not flare up later on jeopardizing the
prognosis of the prosthesis.

8.  Buried root tips or impacted teeth that show no signs of any
pathosis and are encapsulated by normal appearing bone need
not be surgically removed though it must be noted in the
diagnosis.
 It should be checked for any imparted 3 r d molars.
Roentgenographic interpretation
Radiographic interpretation most pertinent to partial denture
construction are those relative to prognosis of remaining teeth that may be
used as abutments.
The quality of the alveolar support of an abutment tooth is of prime
importance because the tooth will have to withstand greater stress loads
when supporting a dental prosthesis, especially greater horizontal forces.
Abutment teeth adjacent to distal extension bases are subjected not only to
vertical and horizontal forces but to torque as well.

9. FIXED PARTIAL DENTURES
A well defined, complete mouth radiographic series is essential.
TMJ radiographs may be indicated for patients with joint
dysfunction and a panoramic radiograph can also be helpful.
Radiographs provide information that cannot be determined
clinically, they are an adjunct, however, and not the sole or
primary source of diagnostic information.
The radiographic interpretation is combined with all other
available findings when making a definitive diagnosis and
developing a treatment plan.
Radiographs used in FPD are
1. Full mouth intra-oral periapical radiographs
2. Panoramic radiographs.
3. TMJ radiographs.
Full mouth intra oral radiographs
An intra oral radiographic examination reveals.
1. Remaining bone support
After horizontal bone loss from periodontal disease the
PDL supported root surface area can be dramatically
reduced. When one third of the root length has been
exposed half the supporting area is lost.
2. Root number and morphology (short, long, slender, broad,
bifurcated, fused dilacerated etc) and root proximity. Molar
with divergent roots provide better support than a molar
with little or no inter radicular bone.
3. Quality of supporting bone trabacular patterns and reaction
to functional charges.
4. Width of the periodontal ligament spaces and evidence of
traum from occlusion.
5. Areas of vertical and horizontal osseous resorption and
furcation invasions.
6. Axial inclination of teeth (degree of non parallelism if
present). A well aligned tooth will provide better support
than a tilted one.
7. Continuity and integrity of the lamina dura.
8. Pulpal morphology and previous endodontic treatment with
or without post and cores.

10. 9. Presence of apical diseases, root resorption or root
fractures.
10. Retained root fragments, radiolucent areas, calcification,
foreign bodies, or impacted teeth.
11. Presence of carious lesions and restorations to the pulp and
alveolar crest.
12. Proximity of carious lesions and restorations to the pulp
and alveolar crest.
13. Calculus deposits.
14. Oral roentgenographic manifestation of systemic disease.
15. Edentulous areas
Presence of retained root tips or other pathosis in the
edentulous area should be noted. In many radiographs it is
possible to trace the outline of the soft tissue in edentulous
areas so that the thickness of the soft tissue overlying ridge
can be determined.
16. Crown – root ratio. (Ante’s Law)
This ratio is a measure of the length of tooth occlusal to the
alveolar crest of bone compared with the length of root
embedded in the bone. As the level of the alveolar bone
moves apically, the level arm of that portion out of the bone
increases and the chance for harmful lateral forces is
increased. The optimum crown root ratio for a tooth to be
used as a fixed partial denture abutment is 2:3. A ratio of
1:1 is the minimum ratio that is acceptable for a prospective
abutment under normal circumstances.
17. Size and position of the pulp
This is one of the most important factors to be assessed
before preparing a tooth and may well determine the correct
choice of retainer. Where the pulp is large particularly in
the young patient, it may be impossible to obtain sufficient
reduction of tooth tissue for adequate retainers without
devitalization. This is especially true of the bonded
porcelain restorations, where quite drastic reduction of
tooth tissue is essential if a good esthetic result is to be
obtained.
On occasions where devitalization is required it is far better
if this is elective rather than following an exposure. In the
posterior region a bitewing X-ray is the best method of

11. assessing the correct position of the pulp. With anterior
teeth an X-ray taken with the ray at right angles to the
crown of the tooth is to be preferred to the usual apical
view.
Panoramic radiographs
Panoramic films provide useful information as to the
presence or absence of teeth. They give an overall view about the
dentition. However they do not provide detailed view for
assessing bone support, root morphology, or caries.
Special radiographs
There are needed for the assessment of TMJ disorders. A
trans-cranial exposure with the help of a positioning device , will
reveal the lateral third of the mandibular condyle and can be used
to detect structural and positional changes.
However interpretation may be difficult. More information
can be obtained from serial tomography, arthrography, CT
scanning or magnetic resonance imaging of the joints.

12. IMPLANT IMAGING
Radiographic visualization of potential implant sites is an
important extension of clinical examination and assessment.
Radiographs help the clinician to visualize the alveolar ridges
and adjacent structures in all three dimensions and guide the
choice of site, number, size and axial orientation of the implants.
Site selection includes consideration of adjacent anatomic
structures. Pathologic conditions, that could compromise the
outcome must be identified & located relative to the site of the
proposed implant. A variety of radiographic techniques are
available to assist the clinicians.
Radiographs are useful in the Implant dentistry mainly at
three levels.
1)
Preprosthetic implant imaging.
2)
Surgical and interventional implant imaging.
3)
Post prosthetic implant imaging.
IMAGING OBJECTIVES
I. Preprosthetic imaging
Objectives includes Information about
1. Quality, quantity and angulation of bone.
2. The relationship of critical structures to the prospective
implant sites.
3. Presence or absence of disease at the proposed surgery
sites.
II. Surgical and Interventional imaging
The objectives of this phase are
1. To evaluate the surgery sites during and immediately
after surgery.
2. Assist in optimal position and orientation of dental
implants.
3. Evaluate the healing and integration phase of implant
surgery.
4. Ensure abutment position & prosthesis fabrication are
correct.

13. III. Post prosthetic imaging
The objectives of this phase are
1.
To evaluate the long-term maintenance of implant
rigid fixation and function, including the crestal bone levels
around each implant.
2.
To evaluate the implant complex.
IMAGING MODALITIES
The imaging modalities can be described as either analog or
digital and two dimensional or three dimensional.
a)
Analog Imaging modalities
 Periapical radiography.
 Panoramic radiography
 Occlusal radiography
 Cephalometric radiography
b)
Three dimensional imaging modalities
 Computed tomography
 Magnetic resonance imaging
 Interactive computed tomography.
c)
Quasi – three dimensional imaging modalities
 X-ray tomography
 Some cross – sectional panoramic imaging techniques.
Periapical radiograph
Peri-apical radiography provides high resolution planar
images of a limited region of the jaws. They provide a lateral
view of the jaws and no cross sectional information. Even with
adjacent peri-apical radiographs made with limited oblique
orientations, third dimensional information is of little use for the
implant imaging.
Periapical radiographs may suffer from both distortion &
magnification.
The long cone paralleling technique will
eliminate distortion and limit magnification less than 10%. In
order to visualize opposing cortical pate, the image most often
must be foreshortened. As a result, the actual available bone
height may be difficult to determine.

14. In terms of the objectives of preprosthetic imaging,
periapical radiography is
1.
A useful high – yield modality for ruling out local
bone or dental diseases.
2.
Of limited value in determining quality because the
image is magnified, may be distorted and does not depict
the third dimension of bone width.
3.
Of limited value in determining bone density or
mineralization.
4.
Of value in identifying critical structures, but of little
use in depicting the spatial relationship between the
structures at the proposed implant site.
In preprosthetic phase, these films are most often used for
single tooth implants in regions of abundant bone width.
Occlusal radiograph
Occlusal radiographs produce high resolution planar images
of the body of the mandible or maxilla. Maxillary occlusal
radiographs are inherently oblique and so distorted they are of no
quantitative use for implant dentistry for either determining the
geometry or the degree of mineralization of the implant site.
Mandibular occlusal radiograph is an orthogonal projection.
It is a less distorted projection than the maxillary occlusal
radiograph. But, the mandibular alveolus flares anteriorly and
demonstrates a lingual inclination posteriorly, producing an
oblique and distorted image of the mandibular alveolus, which is
of little use in implant dentistry. In addition it shows the widest
width at the crest, which is where the diagnostic information is
needed most.
As a result occlusal radiographs are rarely indicated for
diagnostic preprosthetic phase in implant dentistry.
Cephalometric radiographs
The geometry of cephalometric imaging devices results in a 10%
magnification to the image with a 60 inch focal object and a 6
inch object to film distance.

15. The primary advantages of cephalometric radiographs in
implantology are:
a.
A cross sectional image of the alveolus of both the
mandible and the maxilla in the mid sagittal plane is
demonstrated by this radiograph.
b.
With slight rotation of the cephalometer, a cross
sectional image of the mandible or maxilla can be
demonstrated in the lateral incisor or in the canine region
as well.
c.
It demonstrates the spatial relationship between
occlusion and esthetics with the length, width, angulation,
and geometry of the alveolus.
d.
It is more accurate for bone quality determination,
unlike panoramic or periapical images.
e.
It demonstrates the geometry of the alveolus in the
anterior region and the relationship of the lingual plate to
the patients’ skeletal anatomy.
f.
Together with regional periapical radiographs,
quantitative spatial information is available to demonstrate
the geometry of the implant site relationship with that of
the critical structures.
Panoromic radiography
This modality is probably the most utilized diagnostic
modality in implant dentistry. However for quantitative preprosthetic implant imaging, it is not the most diagnostic. This
radiograph produces an image of a section of the jaws of variable
thickness and magnification.
Panoramic radiography is characterized by an image of the
jaws
that
demonstrates
both
vertical
and
horizontal
magnification, along with a tomographic section thickness that
varies according to the anatomic position. It produces a
relatively constant vertical magnification of approximately 10%.
The horizontal magnification of approximately 20%.
The nonuniform magnification of structures produces
images with distortion that cannot be compensated for in
treatment planning.
The posterior maxillary regions are
generally the least distorted regions of a panoramic radiograph.

16. Panoramic images offer the following advantages
1.
Opposing landmarks are easily identified.
2.
Vertical height of bone initially can be assessed.
3.
The procedure is performed with convenience, ease, and
speed in most dental offices.
4.
Gross anatomy of the jaws and any related pathologic
findings can be evaluated.
Disadvantages are
1.
It does not demonstrate bone quality / mineralization.
2.
It
is
misleading
quantitatively
because
of
magnification and because of the third dimension cross
sectional view is not demonstrated
3.
It is only of some use in demonstrating critical
structures but of little use in depicting the spatial
relationship between the structures and dimensional
quantization of implant site.
Diagnostic templates that have 5 mm ball bearing or wires
incorporated around the curvature of the dental arch and worn by
patient during the panoramic X-ray examination enable the
clinician to determine the amounts of magnification in the
radiograph.
A technique for evaluating the panoramic radiograph for
mandibular posterior implants and comparing this to the clinical
evaluation during surgery was developed by identifying the
mental foramen and the posterior extent of the inferior alveolar
canal. “Sunder Dharmar” proposed that approximately 5 degree
downward tilt of the patient head with reference to the Frankfort
horizontal reference plane, showed mandibular foramen,
mandibular canal and mental foramen in 91% of the radiographs.
Zonography
Recently a modification of the panoramic X-ray machine
has been developed that has the capability of making a cross
sectional image of the jaws. These devices employ limited angle
linear tomography (Zonography) and means of positioning the
patient. The tomographic layer is of approximately 5 mm. This

17. technique enables the appreciation of spatial relationship
between the critical structures and the implant site and
quantification of the geometry of the implant site.
The
tomographic layers are relatively thick and have adjacent
structures that are blurred and super imposed on the image,
limiting the usefulness of this technique for individual sites,
especially in the anterior regions.
Tomography
The diagnostic quality of the resulting tomographic image
is determined by the type of tomographic motion, the section
thickness and the degree of magnification.
The type of
tomographic motion is probably the most important factor in
tomographic quality.
Hypocycloidal motion is generally
accepted as the most effective blurring motion. Large amplitude
tube travel and 1 mm sections are preferred for high contrast
anatomic objects whose geometry changes in a relatively short
distance, such as the alveolus of the jaws. Magnification varies
from approximately 10 – 30% with higher magnification
generally producing higher quality images. Dense structures may
persist in the tomographic image ever though they are 3 – 4 times
the tomographic layer thickness and distant from the tomographic
section.
The use of tomography prosthetic implant imaging are
1.
Enables quantification of the geometry of the alveolus.
2.
Enables determination of the spatial relationship between
the critical structures and the implant site.
3.
Enables appreciation of the quasi three dimensional
appearance of the alveolus.
4.
The quantity of alveolar bone available for implant
placement can be determined by compensating for
magnification.
5.
Post imaging digitization of tomographic implant images
enables use of a digital ruler aid in the determination of
alveolar bone for implant placement.
6.
Image enhancement can aid in identifying critical
structures such as the inferior alveolar canal.

18. Limitations
Not used in determining bone quality or identifying dental
and bone disease.
Linear Tomography
It has been shown to be acceptable for the evaluation of
single implant sites or multiple sites within a single quadrant.
For the assessment of a greater number of sites, this technique
was found to be too time consuming because of the additional
calculations required to locate the patients’ position relative to
the central ray of the X-ray beam. Submento vertex radiograph
is used to determine the correct angulation of the X-ray beam
location of the cross – sectional plane of the image.
Advantages
Linear tomography is capable of producing tomograms
with layer thickness of approximately 3 mm and a range of
magnification from 6 – 10% .Accuracy in this range was found to
be adequate as confirmed surgically.
Multidirectional or Polydirectional Tomography
This includes hypocycloidal and spiral. In theory it should
provide images of superior quality to linear tomography because
of more uniform blurring. However no direct comparison of the
efficacy of linear tomography and complex motion tomography
has been reported.
Advantages
Compared to panoramic radiography, they have shown to be
more precise in measuring the distance between the alveolar crest
and the mandibular canal.
DIGITAL RADIOGRAPHY
Intra Oral Radiography
Direct digital intra oral imaging is a technique emerging as
an alternative to film radiography.
Advantages Includes
1.
Reduced patients’ exposure to radiation.

19. 2.
3.
4.
5.
6.
7.
8.
Increased patient comfort while the radiographic image
is taken.
Instant results and eliminates the inconvenience
associated with developing film.
The images produced by digital technology can be
manipulated. The contrast can be enhanced to facilitate
immediate diagnosis.
Video conversion improves visualization by allowing for
switching between negative and positive or from black and
while to white and black image.
Color also can be enhanced.
The images can be inverted and rotated to 90 degrees.
The distance measurement icon allows for documentation
of distance between different points of an image in 0.1 mm
increments. This is most useful in implants.
Computed Tomography
Computed tomography has been widely advocated for
implant site assessment especially in the posterior regions of the
jaws and for complex cases. CT studies are planned on a lateral
scout image of the selected jaw with alignment corrections made
as needed. Direct axial image are acquired as thin, overlapping
axial scans with approximately 30 axial sections per jaw. These
images are usually acquired perpendicular to the long axis of
body. The sequential axial images subsequently are manipulated
to produce multiple two dimensional images in various planes,
using a computer based process called multiplanar reformatting
(MPR).
In general three basic images are reformatted
1. Axial images with a superimposed curve
2. Cross sectional images
3. Panoramic like curved linear images.
An axial scan including the full contour of the mandible (or
maxilla) at a level corresponding to the dental roots is selected
as a reference for the reformatting process. The computer places
a series of dots on the selected scan and connects them to
develop a customized arch or curve unique for each jaw. The

20. computer program then generates a series of lines perpendicular
to be curves.
These lines are made at constant intervals. Usually 1 to 2
mm and numbered sequentially on the axial image to indicate the
position at which each cross sectional slice will be reconstructed.
Cross sectional reconstructions are made perpendicular to the
curve and panoramic (curved liner) reconstructions are made
parallel with the curve. Three dimensional representations may
also be constructed in various orientations.
Uses In Preprosthetic Implant Imaging
These reformatted images provide the clinician with two
dimensional diagnostic information in all the three dimensions.
Reformatted CT studies provide diagnostic information in all
available implant sites within a dental arch. The reformatted
images typically are presented life size on photographic prints or
radiographic film.
It provides information of the continuity of the cortical
bone plates, residual bone in the mandible and maxilla, the
relative location of soft tissues covering the osseous structures.
Studies have reported that 94% of CT measurements
between the alveolar crest and wall of the mandibular canal were
accurate within 1mm. Three dimensional reformations are
particularly useful in the planning of angumentation
procedures such as a sinus lift.
The density of structures within the image is absolute and
quantitative and can be used to differentiate tissues in the region
and characterize bone quality
Misch Bone density classification
D1 - Dense cortical bone
D2 - Thick dense to porous cortical bone on crest and
coarse trabacular bone within
D3 - Thin porous cortical bone on crest and fine
trabacular bone within
D4 - Fine trabacular bone
D5 - Immature, non mineralized bone

21. CT Determination of bone density
D1 :
> 1250 Hounsfield Units
D2 :
850 – 1250 Hounsfield Units
D3 :
350 – 850 Hounsfield Units
D4 :
< 150 Hounsfield Units
Thus CT is capable of determining all the radiologic objectives
of preprosthetic implant imaging.
Interactive computed tomography: [ICT]
(SIM / Plant Software, columbia scientific, Inc.,)
This addresses many of the limitations of CT.
This
technique enables the radiologist to transfer the imaging study to
the clinician as a computer file and enables clinician to view and
interact with imaging study on their own computer.
The clinicians’ computer becomes a diagnostic radiologic
work station with tools to measure the length and the width of
the alveolus; measure bone quality, the change the window and
level of the grey scale of the study to enhance the perception of
critical structures. Axial, cross sectional, and panoramic images
are displayed and referenced so that the clinician can appreciate
the same position or region within the patients anatomy in each
of the images.
As important features of ICT is that the clinician and
radiologist can perform “electronic – surgery” (ES) by selecting
and placing arbitrary size cylinders that simulate root form
implants in the images.
With an appropriately designed
diagnostic template, ES can be performed to electronically
develop the patients’ treatment plan in three dimensions.
ES & ICT enable the development of a three dimensional
treatment plan that is integrated with the patients anatomy and
can be visualized before surgery by the members of the implant
team and the patient for approval or modification.

22. Limitations
1.
Refinement and exact relative orientation of
the implant position is difficult and cumbersome.
2.
Parallelism is difficult to appreciate in ICT
using orthogonal rather than three dimensional images.
Magnetic Resonance Imaging: (MRI)
MR used in implant imaging as a secondary imaging
technique when primary imaging techniques such as complex
tomography, CT or ICT fail.
Failure to differentiate the inferior alveolar canal may be
caused by osteoporotic trabacular bone and poorly corticated
inferior alveolar canal.
The uses of MR are
1. MR visualizes the fat in trabacular bone and differentiates
the inferior alveolar canal and neurovascular bundle from
the adjacent trabacular bone.
2. Double scout MR imaging protocols with volume and
oriented cross Sectional imaging of the mandible produce
orthogonal quantitative contiguous images of the proposed
implant sites.
Limitations
MR is not useful in characterizing bone mineralization or a
high – yield technique for identifying bone or dental disease.
DIAGNOSTIC TEMPLATES
A diagnostic radiographic template is used to incorporate
the patient’s proposed treatment plan into the radiographic
examination. This information can then be used to alter implant
angulation and position, achieving optimal implant body
placement within the available bone & preserving vital
structures. The end result of this process is the fabrication of a
surgical implant that will enable the surgeon to place the
implants in their proper positions.

23. The preprosthetic imaging procedures enable evaluation of
the proposed implant site at the ideal position and orientation
identified by radiographic markers incorporated into the
template.
The radiopaque markers used are
1.
Barium sulphate
2.
Lead foil
3.
Gutta percha
4.
Metal sleeves (set up disks)
Of this lead foil is of limited use. Because of larger lead
atom causes distortion of the image at the localized site occurs.
Diagnostic templates used in computed tomography.
The precision of CT enables the use of complex and precise
diagnostic templates. Although CT scan can accurately identify
the available bone height and width for a dental implant at a
proposed implant site, the exact position and orientation of
implant, which many times determines the actual length and
diameter of the implant, is often dictated by the prosthesis.
The surfaces of the proposed restorations and exact position
and orientation of each dental implant should be incorporated
into the diagnostic CT template.
Many designs have been
proposed for diagnostic CT templates.
They are basically two forms.
1.
Produced from a vacuumform reproduction
2.
Produced from a processed acrylic reproduction of the
diagnostic wax up.
Vacuumform Template
A number of variations have been proposed.
1.
Coating the proposed restoration with a thin film of
barium sulfate. Although the proposed restoration becomes
evident in the CT examination, the ideal position &
orientation of the proposed implant is not identified by this
design.
2.
The proposed restoration sites are filled in the vacuform
of the diagnostic wax up with a blend of 10% barium
sulfate and 90% cold cure acrylic this results in radiopaque
tooth appearance of the proposed restorations in the CT

24. examination which matches the density of enamel and
dentin of natural teeth but does not identify the exact
position and orientation of the proposed implant site.
3.
Modification of previous design by drilling a 2 mm hole
through the occlusal surface of the proposed restoration at
the ideal position and orientation of the proposed implant
site with twist drill. This results in a natural tooth like
appearance to the proposed restoration in the CT
examination where all the surfaces of the restoration are
evident along with a 2 mm radiolucent channel through the
restoration, which precisely identifies the position and
orientation of the proposed implant.
Processed acrylic template
The processed acrylic template is modified by coating the
proposed restoration with a thin film of barium sulfate and filling
a hole drilled through the occlusal surface of the restoration with
gutta percha. The surfaces of the proposed restoration then
become radiopaque in the CT examination and the position and
orientation of the proposed implant is identified by the
radiopaque plug of gutta-percha within the proposed restoration.
Diagnostic Templates used for Tomography
Diagnostic templates for tomography examinations are
generally less precise than those required in CT examinations.
The diagnostic information available from tomography
examinations is not as detailed or as precise as that available
from CT examinations.
1.
The simplest tomography template is produced by
obtaining a vacuform of the patient’s diagnostic cast with 3
mm ball bearing placed at the proposed implant positions.
A number of tomograms of the implant region are produced
with the implant site identified by the one in which the ball
bearing is in sharp focus. The ball bearing can additionally
serve as a measure of the magnification of most
tomographic imaging system.
2.
Templates that incorporate metal cylinders or tubes at
the proposed implant sites also enable evaluation of
tomograms for the orientation along with the position of the
proposed implant.
3.
The diagnostic template used in CT examination, which
is produced from a vacuform of the patients diagnostic cast

25. with barium coating of the proposed restoration and
orthodontic wires to indicate the position and orientation of
the proposed implant, can also be used for tomography and
provide the most diagnostic information of templates
described.
Dual purpose templates
Diagnostic templates can be modified and used as surgical
templates. If metamorphosis from diagnostic template to surgical
template is the objective of the surgeon, the diagnostic template
should be selected and fabricated with that in mind. Typically
bench modification of a diagnostic template to produce a surgical
template does not incorporate the precision of the results of ICT
or ES.
CAD/CAM Stereo Tactic Surgical Templates
Anatomically accurate three dimensional models of the
patients’ alveolar anatomy can be produced by a number of CAD/
CAM and rapid prototyping procedures. CAD/ CAM surgical
stereotactic templates can be produced from CT examinations
that have used interactive CT to develop a three dimensional
treatment plan for the patient of the position and orientation of
dental implants.
2. Surgical and Interventional Imaging
Surgical and interventional imaging involves imaging the
patient during and immediately after surgery and during the
placement of the prosthesis.
Purpose
1. To evaluate the depth of implant placement
2. To evaluate the position and orientation of implants /
osteotomies.
3. To evaluate donor or graft sites.
Modalities used
1. periapical radiographs.
2. panoramic radiographs.
Film based intra-oral radiography
The patient can be generally imaged at chair side with
periapical radiography to determine implant/osteotomy depth,
position and orientation. Corrections for magnification similar to
those employed in endodontics are necessary to quantify the

26. depth of osteotomy. The disadvantage of periapical radiography
is that a dark room and approximately 5 minutes radiography for
film processing is generally required.
Digital periapical radiography
Digital periapical image receptors enable virtually
instantaneous image acquisition, produce image quality similar to
that of dental film and enable the surgical procedure to proceed
without undue delay.
Additional features of digital imaging such as image
enhancement and use of digital measuring techniques can help
the surgeon in establishing the optimum depth and orientation of
the implants.
Panoramic radiography
For extensive implant procedures that may involve the
entire jaw, both jaws, large donor graft sites, or sinus
argumentation, panoramic radiography will provide a more
global view of the patients’ anatomy.
The disadvantage of panoramic radiography is that the
patient must generally leave the surgical suite and stand or sit for
the panoramic procedure. A panoramic radiography has less
resolution than the periapical radiography.
Clinical assessment
Periapical or digital periapical radiography is useful
modality to determine if the implants components and prosthesis
are seated or fitted appropriately. The anti rotation device of the
implant body may prevent the abutment from seating in the
correct position. This may be difficult to ascertain because the
implant crest module is often at the bone crest and the tissue is
several millimeter thick. An x-ray examination is also performed
to determine of the metal frame work and / or final restoration is
completely seated, and the margins are acceptable around the
implants and/or teeth.
The important portion to image is the crestal aspect of the
implant not the apex.
3. Post Prosthetic Imaging
The purpose of post prosthetic implant imaging is to
evaluate the status and prognosis of the dental implant. The bone
around to the dental implant should be evaluated on a routine

27. basis for changes in mineralization or bone volume. Changes in
bone mineralization in the region of bone adjacent to the dental
implant may indicate successful integration, fibrous tissue
interfaces, inflammation or infection, loss of crestal bone volume
adjacent to the dental implant, excessive functional loading or
Para-functional loading.
Periapical Radiography
The implants bone interface is depicted only at mesial,
distal, inferior or crestal aspect or where the central ray of the xray source is tangent to the implant surface, evaluating the dental
implant for changes in bone mineralization or bone volume in
alveolar bone adjacent to the implant requires evaluation of
temporally acquired periapical radiographs.
The angulation of the x-ray beam must be within a degree
of the long axis of the fixture to open the threads on the image
on most threaded fixtures. Angular deviations of 13 degrees or
more result in complete overlap of the threads. In general
periapical radiographs are appropriate for longitudinal
assessments.
Mesial & distal marginal bone height is measured using
known inter thread measurements and comparing that with the
bone level in previous periapical radiographs. Studies suggest
that the rate of marginal bone loss after successful implantation
is approximately 1.2mm in the first year, subsequently tapering
of to about 0.1mm in succeeding years. Occasionally areas of
marginal bone gain also may be noted.
Bite wing radiography
The short and long term evaluation of crestal bone loss
around implants is best evaluated with intra oral radiographs. A
vertical bite wing radiography is often ideal and much easier to
position once the prosthesis is in place.
Most threaded implants have a smooth crestal region that
measure 0.8 – 2mm depending upon the manufacturers. There is
constant distance between the threads. As a result, the amount of
crestal bone loss can be determined when compared to the
original implant insertion.

28. The image is optimal when the implant body threads can be
seen clearly on both sides.
Quality periapical or bite wing radiographs placed parallel
to the implant body with the central ray of source oriented
perpendicular to the film will enables sequential radiographs for
crestal and peri implant bone loss. Radiographs produced in this
manner should result in a relatively undistorted image of the
body of the implant, the implant abutment connection and / or
threads.
Radiographic signs associated with failing endosseous
implants:
Radiographic Appearance
Clinical Implications
Thin radiolucent area that Failure of the implant to
closely follows the entire integrate with adjoining bone.
outline of the implant.
Radiolucent area around the Peri implantitis resulting from
coronal portion of the implant
poor plague control, adverse
loading or both.
Apical migration of alveolar Non axial loading resulting
bone on one
side of the from improper angulation of the
implant
implant.
Widening
of
periodontal Poor
stress
distribution
ligament space of the nearest resulting from bio mechanically
natural abutment.
inadequate prosthesis implant
system.
Fracture of the fixture.
Unfavorable stress distribution
during function.
Temporal digital subtraction radiography (SR)
It is a radiographic technique that enables two radiography
made at different points of time of the same anatomic region to
be subtracted resulting in an image of the difference between the
two original radiographs. SR requires the same orientation
between the x-ray source patient and film for each radiograph
which can be accomplished by the use of registration templates.
Additionally, SR requires the radiography to be standardized to
account for changes in exposure and processing between each
radiograph. Then the radiographs can be digitized, registered and

29. subtracted with a resulting subtraction image that simply depicts
the changes in the patient anatomy during the time period
between the radiographic exposures.
Advantages
1.
SR has been shown to be considerably more accurate
at depicting changes in bone mineralization and bone
volume than simply viewing the original periapical
radiographs.
2.
In addition to identifying mesial and distal changes in
alveolar bone, SR can also depict buccal and lingual
changes in alveolar bone.
3.
SR has been the modality of choice for depicting
temporal changes of alveolar bone for clinical and research
studies.
Disadvantages
1.
SR has had limited utilization in clinical practice
because of the difficulty in obtaining reproducible
periapical radiographs.
2.
Both periapical and SR techniques have limitation in
determining buccal and lingual changes in alveolar bone.
3.
Absolute quantization of trabacular bone, and
4.
Depiction of the three dimensional relationship
between the dental implant and surrounding trabacular and
cortical bone.
Computed tomography
The advantages of CT are
1.
The resolution.
2.
The quantitative gray scale evaluation.
3.
Three dimensional characteristics of CT enable
evaluation of the bone implant interface in all orientations.
4.
Failing implants characterized by trabacular and
crestal demineralization, resorption of the bone implant
interface, cortical plate fenestrations and perforation of the
inferior alveolar canal cortical plates and nasal cavity or
maxillary sinus floor can be identified with CT.
5.
CT also demonstrates the results of sinus
augmentation surgery.
6.
Unlike conventional imaging techniques such as
periapical or panoramic anatomy, the resolution, spatial

30. discrimination, and the three dimensional imaging
capabilities of CT enable precise evaluation of the position
of dental implants relative to critical structures such as the
inferior alveolar canal, the mental foramen, maxillary sinus,
nasal cavity, incisive foramen, anterior loop adjacent teeth,
buccal or lingual cortical plates and so on. And suffers
from magnification and distortion.
MAXILLOFACIAL PROSTHODONTICS
Radiographs play major role in maxillofacial rehabilitation of intra and
extra oral facial structures which have been congenitally malformed or
lost due to trauma.
Main Indications for Maxillofacial radiographing are
1. Fracture of maxillofacial skeleton
2. Embroyonic abnormalities of maxillofacial region
3. fracture of skull
4. investigations of antra
5. diseases effecting skull base and vault
6. TMJ disorders
The extent of damage to tissues needed to be rehabilitated and extent
of underneath supporting tissues vital for receiving maxillofacial
prosthesis to be analysed by various radiographic views of
maxillofacial prosthesis and treatment plan is executed.
Radiographs of maxillofacial region are
1. I ntraoral radiographs – IOPA, bitewing etc
2. Extraoral radiographs – most commonly used maxillofacial
imaging.
Ex. P-A Projection (Granger projection )
Inclined P-A (Caldwell projection)
Most maxillofacial rehabilitations in Prosthodontics include closure
of developmental defects like clefts and eye , ear, nose and cranial
prosthesis lost due to trauma which go best with radiographic
evidence.
For best visualization of clefts most preffered radiographs are
1. Occlusal radiographs.
2. Lateral Cephalogram

31. 3. CT scan
4. Ultrasound
Radiographs in maxillofacial sinuses
1. Standard occipeto mental projection( 0 degress)
2. Modified method (30 degrees mental projection)
3. P-A Waters view
4. Bregma menton view
Radiographs of mandible
1. P-A mandible
2. Rotated P-A mandible
3. Lateral oblique
a. Anterior body of mandible
b. Posterior body of mandible
c. Ramus of mandible
Radiographs of Zygomatic arches
1. Jughandle view
Radiographs of base of skull
1. Submentovertex projection
Radiographs of skull
1. Lateral cephalogram
2. True lateral cephalogram
3. P-A cephalogram
4. P-A skull
5. TOWNES projection
Radiographs of TMJ imaging
1. Panoromic radiography
2. Transcranial projection
3. Tomography
4. Arthromography
5. Arthromography with videofloroscopy
6. MRI
7. Computed tomography

32. TMJ interpretation
Roentgenograms are of value for differential diagnosis in that other
pathologic condition having signs and symptoms similar to traumatic
TMJ arthritis may be distinguished by roentgenographic changes.
Roentgenographic changes associated with Osteoarthritis of TMJ are
1. Lack of definition of anterior aspect of condyle
2. Peripheral lipping of bone of condyle with flattening of articular
surface
3.resorption of bone at posterior aspect of articular tubercle towards
glenoid fossa.
4. Fragmentation of meniscus
5. Dystrophic calcification
Presence of tumor , cyst and fracture should be ruled out before a
final diagnosis is made on tmj and occlusal related problems.
Usually such problems can be detected from panorex radiograph.
Panorex radiographs presents the entire joint region and ascending
ramus in clarity and completeness, they are most practical for use in
differential diagnosis of TMJ.
Radiographic examination procedures for TMJ should always include
periapical films.
Radiographs are important third step in making differential diagnosis.
Four basic radiographic techniques can be used in most dental
offices for evaluating the TMJ
1. panoramic view
2. Lateral transcranial
3. Transpharangeal
4. Transmaxillary or A-P view
More sophisticated techniques include
1. Tomography
2 Arthrography
3. MRI

33. 4. Bone scanning
Alternate and specialized imaging modalities
Research and development have focused on manuplating and altering
all three basic requirements of image production i.e the patient, image
generating equipment and image receptor.
New softwares are being developed to manuplate the image itself
once it has been captured.
Many of imaging modalities are playing increasing role in dentistry.
Many of imaging modalities are playing increasing role in dentistry.
Main specialized imaging modalities are
1. Contrast studies
2. Radioisotope imaging
3. Computed tomography
4. Cone beam CT (CBCT)
5. Ultrasound
6. Magnetic resonance

34. Conclusion
Proper modality of radiographic interpretation, good technical skill in
taking radiograph, thorough radiographic study, proper interpretation
help to reach a perfect diagnosis and optimum treatment .Arriving at
definite diagnosis and treatment plan is challenging task in
Prosthodontics which is made easy by radiographic interpretation.
Many of abnormalities both intraoral and facial which remain
undetected by inspection for a successful prosthetic rehabilitation
can be detected by radiographs. So ‘eye misses but X-ray catches’.
Radiographs are an adjunct and not the sole or primary source of
diagnostic information.
Good understanding and sound knowledge of various radiographic
modalities and their specificity help to eliminate unnecessary
radiation hazards and control expense of treatment. Radiographs form
final aspect of diagnostic procedure and provide Prosthodontist
correlate all the facts that have been collected listening to the patient ,
examining the mouth and evaluating the diagnostic cast.

35. Reference
 Imaging in Implantology, Bhat.S, Shetty.S, Shenoy K.K,2005,VOL
5,JIPS,Issue 1,page 10-14.
 Basic Implant Surgery, R.Palmer, P.Palmer, Floyd, Vol 187,No
8,OCT 23,1999,BDJ
 Prosthetic treatment of edentulous patients,Zarb-Bolender,12th
edition,2004.
 Essentials of complete denture prosthodontics, Sheldon Wrinkler,2nd
edition,2004.
 Syllabus of Complete dentures,Charles M.Heartwell jr, 4th edi,1984.
 McCrackens Removable partial Posthodontics, 11th edi,Alan B.
Care,Glen .P.Mc Givney,David T.Brown.,2005.
 Clinical removable partial Prosthodontics,2nd
edi,Steward,Rudd,Kuebker,2003.
 Contemporary Fixed prosthodontics,Stefen F. Rosential,2001.
 Tylmans theory and practice of Fixed Prosthodontics,8th edi,
W.F.P.Malone,D.L. Koth,2004.
 Fundamentals of Fixed Prosthodontics,3rd edi.Herbert T.
Shillingberg,1997.
 Functional occlusion From TMJ to SMILE DESIGN,Peter
E.Dawson,1989.
 Management of TM disorders and occluysion,5th edi,Jeffrey P.
Okeson,1998.
 Clinical maxillofacial prosthesis,Thomas D. Taylor,2004.
 Dental implant prosthetics,Carl.F. Misch,1st edi,2004.
 Essentials of dental radiology and radiography,4th edi,Eric
Whaites,2007.
 Text book of Dental and Maxillofacial Radiology,Freny R.
KARJODKAR,2006.
 Oral Radiology principles and interpretations,5th edi,2004.s

36. Contents
 Introduction
 Pioneers in dental radiography
 Radiographs in CD prosthesis
 Radiographs in RPD prosthesis
 Radiographs in FPD prosthesis
 Implant imaging
 Radiographs in maxillofacial prosthodontics
 TMJ interpretation
 Alternate and specialized imaging
 Conclusion
 Reference

37. A Seminar on
RADIOGRAPHS IN PROSTHODONTICS
Presented by
Dr.G.MANMOHAN,
P.G Student,
Date: 27-11-07.
Signature of Prof & HOD

38. SIBAR INSTITUTE OF DENTAL SCIENCES
Guntur-522509