Dental Ct imaging Khorfakhan hospital

1. DENTAL CT IMAGING
G.SRINIVAS RAO
Radiology Technologist
Department of Radiology
Khorfakkan Hospital

2. Talk plan
• INTRODUCTION
• HISTORY
• TECHNIQUE
• PATIENT
• SCANNER PROTOCOLS
• DOSE REDUCTION
• FILMING
• JAW ANATOMY
• JAW PATHOLOGY
• CASE STUDY
• CONCLUSION

3. Introduction:
The jaw comprises two complex bony
structures the mandible and maxilla. Their
curved or arch like configuration makes
radiographic imaging difficult .
The superimposition of dense teeth and roots
may obscure underlying tissue ,and streak
artifact from dental restoration often degrade
CT images.

4. HISTORY:
The technique of Dental CT also called Denta
scan was developed by schwarzet in 1987when
these investigators first used curved
multiplanar Reconstructions of the jaw to
study the jaw anatomy.

5. • Dental CT has become an established method
for imaging the jaw anatomy prior to dental
implant placement.
• The clinical uses of these implants has rapidly
increased.
• The term dental CT does not represent a
particular modality ,but rather a specific
investigation protocol.

6. • The main feature of the protocol include the
acquisition of axial scans of the jaw with the
highest possible resolution together with
curved and Orthoradial Multiplanar
reconstructions.
• Dentists commonly diagnose and work in the
sub millimeter scale ,hence a High Detailed
image quality is required and challenges CT to
its technical limits.

7. Technique:
 For Dental CT
1.Highest possible resolution
2.Optimal image quality
3.Least Radiation Dose

8. Technique:
• Dental CT is performed with the patient supine
with the alveolar edge of the jaw bone
perpendicular to the table top. With the new
multi-slice scanners ,the jaw is scanned about 1-2
minutes.
• Thin slice images (less than 1mm)are
reconstructed and then run through a special
software program ,where panoramic (OPG –like)
and paraxial (perpendicular to the alveolar edge
images are obtained.

9. PATIENT POSITIONING:
• The patients head should be strapped and tilted
so as to minimize the interference of the jaw and
teeth images with artifact stemming from metal
fillings
• The occlusion plane parallel to the scanner light
marker . Immobilize the jaw by patient bite on
cotton. Instruct not to swallow.
• Surview scan should be checked for proper
positioning .
• Any metal objects like jewelry should be
removed from the scan region.

10. PATIENT SCANNING:
• The region to be scanned should include all
the relevant jaw volume the diagnostic
template and the teeth . A few millimeters
should be added beyond the two extremities
in order not to miss relevant volume due to
accidental patient motion.

11. SCAN PARAMETERS
SLICE THICKNESS LOWEST AVAILABLE –max 0.8mm
SLICE INCREMENT Half the slice thickness-max 0.4mm
FIELD OF VIEW Less than 180mm
RECONSTRUCTION ALGORITHM Bone or High Resolution
GANTRY TILT Zero degree

12. DOSE REDUCTION:
• Dental CT images are displayed with a very low
contrast setting (bone window)due to the
excellent contrast between bone and soft tissue.
• Dose reduction protocols to be used. ALARA
• Another possibility dose reduction is to limit the
Scan Range or by excluding the occlusal region
crown of the teeth since their area is easily
investigated by other modalities .

13. Display:
• The paraxial images allow us to evaluate all
the four cortices (alveolar , buccal ,lingual ,
and inferior.)these are then documented on
film thus allowing accurate measurements
with a simple rule to assess the extent of the
bone available for an implant . In the maxilla
if the posterior maxillary height is thin ,dental
CT can help reassess the area after the sinus
lift.

14. Display:
• Many software programs are now available
which incorporate these images into
simulations , which allow the implantologists
to not only obtain the measurements but also
to place virtual implants in some cases jaw
models can be created to help in the surgery.

15. Filming:
• Hard copy if single jaw is scanned all images
can be displayed on three hard copies films
first two are the axial scans of format of four
columns by five rows of slices per hard copy is
chosen ,the remaining reconstructed images
on single precisely in 1:1 (life size scale).Axial
planning slices with centimeter scale that
usually displayed on the image .
• Soft copy is best for more detail viewing

16. USES:
• 1.Implants
• 2.Surgical procedures
• 3.Inflamatory diseases
• 4.Cysts
• 5.Fractures
• 6.Dental pathology

17. Anatomy:

18. Image:
• crown (1)
• pulp (3)
• apical foramen (4)
• alveolar process (5)
• dentin (6)
• enamel (8)
• periodontal (9)

19. Jaw anatomy

20. Jaw:

21. VASCULAR:

22. Axial – plane selected:

23. Post processing:

24. ALVEOLAR CREST
• classification of alveolar
• bone atrophy.
• Grade 1 normal alveolar
• crest tooth in place.
• Grade 2 mild atrophy
• Grade 3 rounded
• Grade 4 knife edge
• Grade 5 flat crest
• Grade 6 depressed
• bone loss

25. DISPLAY:

26. Cross Sectional:

27. mandibular Canal

28. mandibular canal

29. pathology
• periodontal & endodontal disease

30. Pathology:
• sclerotic osteitis

31. pathology
• dentigerous cyst

32. pathology

33. Pathology:

34. Implant:

35. Sim plant

36. CONCLUSION:
Dental CT has validated as an excellent tool for
Diagnosing dental related pathologies. As it
enables quality and quantity of bone. The
reformatted images gives excellent information
about the position of the implant placement
and pathologies.

37. THANK YOU
Have a Good Day