Radiographic aids in dental implants

1. RADIOGRAPHIC AIDS IN DENTAL IMPLANTS
THASLIM FATHIMA N.
SECOND YEAR POSTGRADUATE
DEPARTMENT OF
PERIODONTOLOGY

2. CONTENTS
• Introduction
• Phases of imaging
• Imaging modalities
• Periapical radiography
• Digital radiography
• Panoramic radiography
• Tomography & computed tomography
• Cone beam volumetric tomography
• Interactive computed tomography
• Imaging of vital structures
• Diagnostic templates
• Conclusion
• References

3. INTRODUCTION

4.  Diagnostic imaging techniques must always be interpreted
in conjunction with a good clinical examination.
 The decision is a balance between these factors and the
desire to minimize risk of complications to the patient.
Multiple factors influence the selection of radiographic technique(s) for a particular case,
including cost, availability, radiation exposure, and case type.

5. Some of the key parameters in implant planning where appropriate
imaging can contribute are:
• Bone height (craniocaudal dimension)
• Faciolingual/faciopalatal width
• Mesiodistal dimension
• Bone morphology
• Presence and prominence of anatomic features:
Sublingual and submandibular fossae
Incisive and canine fossae
• Neurovascular canals and foramina, including:
Mandibular canal and the mental foramen
Incisive canal and foramen
Mandibular lingual canals and foramina (Laboda 1990; Mason et al. 1990; Katakami et al. 2009;
Tagaya et al. 2009; Givol et al. 2000)
Greater palatine canal and foramen
• Cortical thickness and density
• Extent and morphology of the alveolar recesses of the maxillary sinus bases.

6. PHASES OF IMAGING
1
.
2 Phase II Surgical and intraoperative implant imaging
Phase I Pre-surgical implant imaging
Phase III Post-prosthetic imaging

7. Pre-surgical implant imaging
To assess the overall status of the remaining dentition
To identify and characterize……

8. Pre-surgical implant imaging
To determine the relationship of critical structures to
the proposed implant site
To detect regional anatomic abnormalities and
pathologies.

9. Surgical & intraoperative implant imaging
Evaluates the sites
during and
immediately after
surgery
Assist in the optimal
position and
orientation of dental
implants
1
2

10. • Surgical & intraoperative phase is focused on assisting in surgical &
prosthetic intervention of patient.
• It aids in evaluating the healing and integration phase of implant surgery.
• It helps to ensure abutment position and prosthesis fabrication.

11. Post-prosthetic imaging
• To evaluate the long-term maintenance of implant rigid fixation and function……

13. Two-dimensional / Three –
dimensional imaging
modalities
Imaging modalities
Analog / Digital imaging
modalities
IMAGING MODALITIES

14. Ideal Requirements of Diagnostic Imaging
Ability to visualize the implant
site in mesiolingual and
buccolingual dimensions.
1
Ability to allow reliable, accurate
measurements ; a capacity to
evaluate trabecular bone density &
cortical thickness; less cost &
minimal radiation risk.
2
Ability to visualize the implant site in
the mesiodistal, buccolingual and
superioinferiorly.
3

15. DIAGNOSTIC IMAGING TECHNIQUES

16. Periapical radiography
Periapical radiographs are images of limited region of mandibular or
maxillary alveolus are used to plan implant placement.
It provides two dimensional information regarding the implant site.
Indications:
Evaluation of small edentulous
spaces
Eg: in case of single tooth
replacement
Alignment and orientation of
implants during surgery
Recall/maintenance evaluations

17. ADVANTAGES
 Amount of bone loss and peri- implantitis can be visualized.
 Subtle variations in bone activity is clearly seen.
 Minimal magnification with high resolution.
 Provides an assessment of the quantity and quality of the
edentulous alveolar ridge & adjacent teeth.
 They are easy to obtain in dental office, Inexpensive.
 Delivers low radiation to the patient.

18. DISADVANTAGES
• Distortion is particularly accentuated in edentulous areas, where missing
teeth and resorption of the alveolus necessitate film placement at
significant angulation in relation to the long axis of the teeth and alveolar
bone.
• Often, it is not possible to image the entire height of the remaining alveolar
ridge, and when extensive mesial-distal areas need to be evaluated,
multiple periapical films are required

19. OCCLUSAL RADIOGRAPHY
• Occlusal radiograph is a planer radiograph produced by placing film intraorally parallel to the occlusal
plane with the central x-ray beam perpendicular to the film for the mandibular image and oblique (usually
45 degrees ) to the film for maxillary image.

20. ADVANTAGES
High resolution planer image
DISADVANTAGES
• The degree of mineralization of
trabecular bone is not
determined by this projection
& spatial relationship between
critical structures such as
mandibular canal & mental
foramen.
• The proposed implant site is
lost with this projection

21. BITEWING RADIOGRAPHY
• Bitewing radiographs are used as post prosthetic imaging.
• The x-ray beam should be angled to be perpendicular to the crestal bone region of the implant
or abutment to implant connection

22. • Quality bitewing radiographs placed parallel to the implant body with central ray of
source oriented perpendicular to the film enable sequential radiograph for crestal and
perimplant bone loss.
• Used as postprosthetic imaging.

23. PANORAMIC RADIOGRAPH
INDICATIONS
• Indicated when multiple implant placements are planned.
• Initial assessment of vertical height of bone
• Evaluation of gross anatomy of the jaws and any related pathologic
findings
• They display image slices through jaws by producing a single image of maxilla & mandible their supporting
structures in a frontal plane.
• The image receptor is either radiograph film or can also be a digital storage phosphor plate.

24. Advantages:
o They display anatomic structures like nasal cavity, maxillary sinus, inferior alveolar canal and mental
foramen.

25. Disadvantages
 The resolution is lesser when compared to intraoral radiographs.
 When compared to intraoral radiograph Cross sectional view is not demonstrated and is of little use
in depicting the spatial relationship between the structures. 10-20% image magnification occurs,
which is non uniform.

26. Tomography
• Tomographic units produce cross-sectional slices of the jaws that can be as thin as 1 mm
and are suitable for pre- and post-implant assessment.
TOMO- slice
GRAPH- picture

27. • The basic principle of tomography is that the x-ray tube and film are connected by a rigid bar called the
fulcrum bar, which pivots on a point called fulcrum.
• When the system is energized, the x-ray tube moves in one direction with the film plane moving in the
opposite direction and the system pivoting about the fulcrum

28. • Linear tomography is the simplest form , which has a one dimensional motion and produces
blurring of adjacent sections and results in linear steak artifacts in the resulting image, which
may obfuscate the section of interest.

29. • Circular, spiral and hypocycloidal are two- dimensional motions
• Hypocycloidal is generally accepted as the most effective blurring motion
• This technique is difficult to use in cases of multiple implant sites.

30. Transtomography / sectional tomography
• This technique enables the appreciation of spatial relationship between the critical
structures and the implant site and quantification of the geometry of the implant site.

31. • The tomographic layers are thick and have adjacent structures that are
blurred and superimposed on image, limiting usefulness of this technique
for individual sites,especially in the anterior regions where geometry of the
alveolar changes rapidly.

32. Advantages
• Cross- sectional views
• Constant magnification Disadvantages:
• Technique- sensitive
• Blurred images
• High radiation dose
• Multiple images needed
• Expensive

33. Computerised Tomography
CT is a digital imaging technique, which can generate 3D images using a very narrow “fan beam” that
rotates around the patient, acquiring one thin slice (image) with each revolution

34. • CT scans have been shown to be very accurate with the magnification effect, the same for both the
anterior and posterior area, from a range of 0% to 6% in horizontal as well as 0-4% in the vertical
dimension.

35. •
• Advantages
• Negligible magnification
• High contrast image
• 3 dimensional bone models
• Interactive treatment planning
Disadvantages
High dose of radiation
Technique – sensitive
Expensive

36. Recent advances in CT
CONE BEAM VOLUMETRIC TOMOGRAPHY
MICROTOMOGRAPH- acquiring serial sections
of bone implant interface
MULTI SLICE HELICAL CT-higher accuracy of
images

37. • CBCT is a three dimensional imaging technique.
• Results in optimal implant placement & improved clinical outcome.
• It helps in improved visualization and comprehension of the anatomy in
the areas in which implants are being planned for placement,
• Helps to visualize the implant site in axial, reconstructed panoramic and
cross sectional views of the jaws.
• CBCT generates cone shaped beams and the images are acquired in one
rotation by an image intensifier of flat panel detector, resulting in
reasonably low levels of radiation dosage.

38. Dentascan
DentaScan is a computed tomography (CT) software
program that allows the mandible and maxilla to be
imaged in three planes: axial, panoramic and cross-
sectional.

39. Cone Beam Volumetric Tomography
• Because of higher radiation exposure, higher cost, huge footprint and difficulty in accessibility
associated with CT, a new type of CT, CBVT was developed.
NewTom 3G by AFP
MercuRay by Hitachi
3D Accuitomo by J. Morita

40. • The x- ray tube on these scanners rotates around 360 degrees and will capture
images of the maxilla and mandible in 36 seconds , in which only 5.6 seconds is
needed for exposure
“ Cone beam” geometry

41. • The images recorded are placed onto a charge- coupled device chip and is
then converted into axial, sagittal and coronal slices and permit reformatting
to view traditional radiographic images as well as 3- dimensional soft tissue
or osseous images.

42. Indications:
• Assess the positions…….
Inferior alveolar canal
Location of neurovascular bundle
The incisive and mental foramina
Pneumatization of the maxillary sinus
Floor of the maxillary sinus
Nasal fossa

43. • Radiation dose from a CBVT scanner is approx. 12.0 mSv , which is equivalent to 25 %
of radiation from a typical panoramic radiograph or to five D-speed dental x-rays

44. Advantages
Almost 0% magnification.
No superimposition or
overlapping of images,
Minimal distortion
Lower cost
More feasible compared to the
CT

45. • Evaluation of bone resorption and root retention, as well as lesions of the facial skeleton.
INDICATIONS:

46. CONTRAINDICATIONS

47. Interactive computed tomography
• This technique enables the radiologist to transfer the imaging study to the practitioner as a
computer file and enables the practitioner to view and interact with the imaging study on their
own computer

48. It helps to measure the length and the width of the alveolus…..

49. • An important feature of ICT is that the dentist and radiologist can perform electronic surgery
(ES) by selecting and placing arbitrary-sized cylinders that simulate root form implants in the
images.

50. • Superimposed on the CBVT image, implants can be virtually
previewed at arbitrary positions and orientations with respect
to each other, the alveolus, critical structures and the
prospective occlusion and esthetics.
• ES and ICT enable the development of a 3D treatment
plan that is integrated with the patient’s anatomy and
can be visualized before surgery.

51. MAGNETIC RESONANCE IMAGING
• It is a 3 dimensional imaging technique. MR images can be varied to obtain fat, water, or balanced
imaging of the patient’s anatomy.
• Oriented MR imaging of the posterior mandible is dimensionally quantitative between critical
structures and the proposed implant site

52. Surgical guides
• Computer generated drilling guides that are fabricated through the process of
stereolithography using SimPlant software for ideal implant positioning

53. • These successive diameter surgical osteotomy drill guides may be either bone, teeth or mucosa-borne.
• Surgiguides have metal cylindrical tubes that correspond to the number of desired osteotomy
preparations and specific drill diameters.

54. • Process wherein the film is replaced by a sensor that collects the data.
DIGITAL RADIOGRAPHY

55.  The resultant image can be modified in terms of gray scale,
brightness, contrast, inversion and color enhancement
 Computerised software programs like Dexisimplant are
available that allowing for calibration of magnified images ,
ensuring accurate measurements

56. ADVANTAGES
• Less radiation
• Superior resolution
• Instantaneous speed of image
formation is highly useful during
surgical placement of implants and
the prosthetic verification of
component placement
DISADVANTAGES
• Size and thickness of the film and
position of the connecting cord
sometimes makes film placement
difficult in some sites , such as
those adjacent to tori or in case of
tapered arch form in the region of
canines

57. IMAGING OF VITAL STRUCTURES IN ORAL
IMPLANTOLOGY

58. Mental foramen and mandibular canal
While using the two-dimensional radiographs for imaging Mental foramen and
mandibular canal ,it is mainly dependent on the positioning.

59. • If the image is taken from the mesio-oblique orientation, measurements will be
fore-shortened

60. Studies have shown that the location of mental
foramen on periapical and panoramic
radiograph are inaccurate and sometimes on
panoramic radiograph it represents a portion of
the mental canal as it leaves the mandibular
canal

61. Several studies have shown CT to be the most accurate
and highly recommended when measurements are
needed for the inferior alveolar canal and mental foramen

62. Mandibular lingual concavities
• When there is advanced atrophy of posterior
mandible, lingual concavities may be present .
• Within these concavities branches of facial artery
may be present

63. Mandibular ramus
Single Onlay Cortical Bone Grafting
The term onlay bone grafting was coined by
Campbell. The technique involves a bone
grafting in which the transplanted tissue is laid
directly onto the surface of the recipient bone.
The technique is more of historical importance.
The technique is rarely used.

64. • Donor site for autogenous onlay bone grafting and is extremely variable in the amount of
bone present .
• Hence adequate assessment of host bone present is not possible
• Recommended : CT

65. Mandibular symphysis
• Donor site for autogenous graft
• Panoramic radiographs mostly overestimate the
height of the available bone in the anterior
region
• Recommended: conventional CT

66. Maxillary sinus
• For implant placement detailed
information is needed regarding the
position of septa, maxillary sinus
anatomy, sinus pathologies.
• CT- the gold standard for evaluation
of sinuses

67. • To verify the positioning and location of an osteotomy site or for identification of a vital structure,
processing of standard radiograph film can take upto 6 minutes and hence is time- ineffcient .
• Current day digital imaging system gives instant images that can be manipulated, and allows accurate
measurements and maintains aseptic protocol
INTRA OPERATIVE
IMAGING

68. Immediate post operative imaging
• A periapical or panoramic radiograph should be taken post surgically so that a baseline image can be
used to evaluate against future images.

69. Abutment and prosthetic component imaging
• When evaluating for transfer of impressions along with the two- piece implant abutment component
placement , radiographs should be taken to verify secure adaptation.
• Intraoral radiographs are recommended because of their high geometric resolution to evaluate for any fit
discrepancy.

70. Post prosthetic imaging
• When investigating complications after implant placement, a panoramic radiograph is the most
ideal technique.
• Whenever Single implant image or a detailed information of implant viewed on panoramic image
is needed, a periapical radiograph is taken.

71. Recall and maintenance imaging
• Follow up or recall radiographs are to be taken 1 year of functional loading and yearly for the first 3
years to assess the marginal bone levels.

72. Radiographic sequence for dental implants imaging
• Pretreatment
• Immediate post surgical (baseline)
• Healing period ( if necessary)
• Second stage surgery
• Post prosthetic surgery ( baseline)
• 1 year postoperatively
• After 1st year, every 2 years

73. Fabrication of diagnostic templates
• The surfaces of the proposed restorations and the exact position and orientation
of each dental implant should be incorporated into the diagnostic CT templates.
• The design may vary from a vaccuformed reproduction of the wax-up - to one
processed from acrylic reproduction of the diagnostic wax-up – to a sophisticated
specially designed radiopaque denture teeth.

74. • The processed acrylic template may be modified by coating the proposed restorations with a
thin film of barium sulfate and filling a hole drilled through the occlusal surface of the
restoration with a gutta-percha.

75. The vaccuform templates involve either coating of
the proposed restorations with a thin film of barium
sulfate. This does not depict the ideal position and
orientation of the proposed implant
Another method is to blend 10% barium sulfate
and 90% cold cure acrylic , which makes the
proposed restoration radiopaque and evident but
again does not give idea about the position and
orientation

76. • Recently radiographic teeth specifically designed for the fabrication of diagnostic
templates have been introduced .
• These are time saving, placed easily, provide consistently high radiopacity, have moulds
corresponding to prosthetic teeth used in the final restoration and are bonded easily with
the template-based material

78. CONCLUSION

79. References
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based planning for oral rehabilitation by means of implants and its transfer to
the surgical field: A critical review on accuracy. J Oral Rehabil 2008; 35: 454-74.

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