Radiology II Forth Year

1. Oro-facial implants
By
Dr. Hassan M. Abouelkheir
BDS, MSC, PhD.

2. Ideal image casting:
• The ability to visualize implant site
buccolingually, mesio-distally & superio-
inferiorly.
• The ability to allow reliable accurate
measurements.
• The capacity to evaluate trabecular density
& cortical thickness.
• The capacity to correlate the imaged site
with clinical site.
• Reasonable access & cost to patient.
• Low radiation dose.

3. Intra-oral Radiography
• 1- Periapical Radiographs:
• It Provide superior resolution
and sharpness.
• Parallel technique is used to
decrease geometric errors.
• They determine vertical
height, architecture and bone
quality (bone density,
amount of cortical &
trabecular bone.
!

4. Intra-oral Radiography (continue):
• Geometric & anatomical
limitations:
• Foreshortening & elongation of
radiographic alveolar height.
• Positioning of film may miss
anatomical structures.
• Unable to provide any cross-
sectional information.

5. 2- Occlusal radiographs:
• Although it gives a clue about facio-
lingual dimension of mandibular
alveolar ridge .
• It records the widest portion of the
mandible which is below the alveolar
ridge .
• It is not suitable for maxilary arch due
to anatomical limitations.
Intra-oral Radiography (continue):

6. Extra-oral radiographs:
• 1- Lateral & Lateral-oblique
cephalometric radiography:
!
• Lateral cephalometric:
has 7% to 12% magnification
It gives the axial tooth
inclination and dento -
alveolar relationships as well
as cross section at midline
only due to over projection
of the lateral areas of the
jaw.

7. Extra-oral radiographs (continue)
2-Oblique Lateral Cephalometric
Radiographs (OLCR)
• One side of the body of the
mandible positioned parallel to the
film cassette.
• A cephalostat with earplugs and a
nasion support was used to position
the head with the porion-subnasal
plane in a horizontal position. A light
beam was used to position the
mandibular lower border with an
inclination of 20 degrees.
• Measurements from this image are
not reliable.

8. Extra-oral radiographs (continue):
!
3- Panoramic radiography:
• It is important for broad visualization
of the jaws and anatomical structures.
• It is useful for preliminary estimations
of crestal alveolar bone and cortical
boundaries of ID canal, max. s. & nasal
fossa.

9. Limitations of panoramic radiography:
1- angular measurements are accurate but horizontal
ones are not.
2 - Magnification (size distortion) varies among films
from different panoramic unites and also at
different areas on the same film.
3- Foreshortening and elongation of vertical
measurements.
4- Overestimation of vertical bone heights.
5- Magnification of horizontal image measurements
as a result focal trough area constructed on
average population (0.70 to 2.2 times actual size) .

10. 4- conventional tomography:
• This technique produces a cross –sectional ,
flat-plane image layer that is perpendicular to
the x-ray beam.
• The complex (multidirectional) tube motion of
current conventional tomographic units
minimizes image superimposition & provide
fixed uniform image magnification for accurate
measurements.

11. • Radiographic stents are used to determine the
width and height of pre-planned implants after
correction with magnification factor as in case of
using scanora integrated imaging system.
• Two or three cross-sectional tomographic slices
are required to preplan each intended implant
site.

12. 5- Reformatted computed Tomography:
It is indicated for :
1- Edentulous pts.
2- Multiple implants.
3- Augmentation procedures.
30 axial images are required per jaw
(1-2mm).
These sequential axis images can be
manipulated by process called
multiplannar reformatting (MPR)
to produce multiple two
dimensional images in various
planes.

13. Reformatted computed Tomography (cont.)
• The CT analysis comes from 3 basic
image types:
• Axial images.
• Reformatted cross-sectional
images.
• Panoramic like images.
• The computer places a series of
sequential dots on selected scan
then connect them to construct a
customized arch .
• Then it places a series of lines at
constant intervals (1-2mm) on axial
image to indicate the position at
which each cross sectional slice will
be reconstructed.

14. Reformatted computed Tomography (cont.)
• These reformatted images
provide the clinician with two-
dimensional diagnostic
information in all three
dimensions.
• It gives information on;
1- amount of cortical bone and
residual bone.
2- location of vital structures.
3- contour of soft tissues.
4- 3D reformations for
augmentation as in maxillary
sinus lifting.

15. Pre-operative planning:
• Diagnostic image can give 3D information
about quality and quantity of alveolar bone.
Quality:
• 1- the thicker the cortical bone the best
withstand for functional load.
• 2- A greater number of internal trabeculae
per unit area is advantageous.

16. Pre-operative planning (cont.):
Quantity:
1- Height .
2- Width of alveolar
bone.
3- Morphology of ridge.
Cross –sectional image
to determine facio-
lingual width and
height , along with
inclination of bone
contour.

17. Pre-operative planning (cont.):
• Pre-planning
measurements in
different technique
shows variable
magnification factor
(MF).
• Radiographic image /
MF to correct
measurements.
• (Pan, Periapical).

18. Pre-operative planning (cont.):
• If MF is constant a
plastic overlay with
1mm grids or diagrams
of available implant
sizes can be used
directly on image.
• Specialized reformatted CT
implant programs can
perform image without
magnification. It can be
printed life size.

19. Imaging stent
• Pre-surgical imaging
can be enhanced by
radiographic stent to
locate the position of
pre-surgical site for
end osseous implant.
• The intended implant
sites are identified by
radiopaque spheres or
rods (metal, composite
resin or Gutta percha).

20. Interactive Diagnostic software:
several interactive
software packages
(e.g. Sim-plant )
allow presurgical
simulation of implant
orientation and
placement.

21. Interactive Diagnostic software:
• There are 3 basic views available
on the Sim/Plant™ screen:
• The Panoramic view is similar to
a normal two dimensional
panoramic view.
• The axial view offers a
perspective from a coronal/
apical direction.
• There is a cross sectional view
that allows a mesial /distal cross
sectional perspective of the
arch.

22. Selecting diagnostic imaging for pre-
operative planning:
1- panoramic view.
2- intraoral periapical films for particular
region of interest.
3- CT if entire maxilla or/and mandible is
required.
4- conventional tomography for few selected
regions.

23. Intra-operative & postoperative assessments:
1- panoramic view.
2- intraoral radiographs.
• Intra- operative films may be required for
confirmation of correct implant placement
or to locate a lost implant.
• Inspection includes;
1- alveolar bone height around implant.
2- the appearance of bone around and
adjacent to implant.

24. Intra-operative & postoperative assessments
• Angulations of x-ray beam
must be within 9 degrees
of long axis of the fixture
to see the sharp image of
threads of fixuture .
• Otherwise angular
deviation of 13 degrees or
more result in complete
overlap to the threads.

25. Intra-operative & postoperative assessments
• Longitudinal assessment of
implant by serial standardized
periapical films using XCP- film
holder with rubber base
impression material to measure;
1- Mesial & Distal bone height from
standard landmark at the collar of
implant.
2- or interthread measurements
compared to bone levels on serial
radiographs.

26. Intra-operative & postoperative assessments
• There is initial circumscribed
resorptive osseous changes
around cervical area of
fixture during 1st
6 months
after surgery.
• It was estimated that there
was marginal bone loss
1.2mm in the 1st
year then
0.1mm in succeeding years.

27. Intra-operative & postoperative assessments
• If any resorptive changes
are present , they
evidenced by apical
migration of the alveolar
bone or indistinct osseous
margins.
• Density can be measured in
intraoral digital radiographs
to measure bone
resorption .

28. Intra-operative & postoperative assessments
• Digital subtraction radiography requires image
geometry reproduction between radiographic
examinations.
• The success of implant can be evaluated by normal
bone surrounding and up to the surface of the
implant .
• No clinical mobility.

29. Radiographic signs of failing endosseous implants:
• Thin radiolucent area
surrounding the entire implant.
• Crestal bone loss around the
coronal portion of the implant.
• Apical migration of alveolar
bone on one side of the implant.
• Widening of PDL space of
nearest natural Tooth
(abutment).
• Fracture of implant fixture.