Applications of X-rays in Dentistry Dental Radiography and Cone Beam Computed Tomography

1. X-rays in Dentistry
Dental Radiography and Cone Beam Computed
Tomography
Dr. Amal Yousif Al-Yasiri
College of Dentistry- University of Baghdad

2. Dental Radiography
• Dental radiographs are commonly called X-rays.
• Dentists use radiographs for many reasons:
1- To see inside teeth (to find hidden dental structures, bone loss, and cavities.
2- To identify disease
3- To evaluate healing
• A radiographic image is formed by X-ray radiation which penetrates oral
structures at different levels before striking the film or sensor.
• Teeth appear lighter because less radiation penetrates them to reach the film (
due to the attenuation). cavities (teeth decay), infections and other changes in the
bone density, and the periodontal ligaments appear darker because X-rays readily
penetrate these less dense structures.
• Dental restorations (fillings, crowns) may appear lighter or darker, depending on
the density of the material.

3. Low signal
Low signal
High signal

4. Film and Digital Radiography
• To create a radiographic image, an image receptor needs to be
placed opposite to the X ray tube
• Both film and digital receptors are used
• While the resulting image looks highly similar, there are
fundamental differences between the way images are formed
using film and digital receptors, as well as differences in terms of
image manipulation, handling and storage.

5. Film Radiography
• In film radiography, Once film has been exposed to X-rays, it needs to
be developed, traditionally using a process where the film is exposed
to a series of chemicals in a dark room, as the films are sensitive to
normal light.
Disadvantages
1-This can be a time-consuming process
2-Incorrect exposures or mistakes in the development process can necessitate
retakes, exposing the patient to additional radiation.

7. Digital Radiography
• In digital radiography, an electronic sensor is used.
• in digital radiography, the dentist inserts a digital sensor into a
patient's mouth to capture images of the teeth .
• The digital sensor is electronic and connected to a computer.
• Once the X-ray is taken, the image is projected on a screen for the
dentist to view.

9. Digital Radiography
Overall advantages of digital radiography over film radiography
1- A digital image can be transmitted electronically to distant locations and can
exist simultaneously at multiple locations
2- The appearance of a digital image can be modified (Image can be
colorized, magnified )
3- A digital image can be stored electronically without occupying physical
space
4- Digital radiography reduces patient radiation dose compared with film
radiography (50% -90%) less radiation than conventional x-ray film
Disadvantages
1-Expensive technology
2- Resolution of the image is slightly less than the conventional x-ray film.

10. Cone Beam Computed Tomography (CBCT)
• In 1988, cone beam computerized tomography (CBCT) was introduced
to dentistry. This technology offered 3-dimensional visualization and
more complex and accurate imaging compared to 2- dimensional
analog and digital radiographs.
• CBCT is one of the most significant advances in dentistry in the last
decade.
• What is Dental Cone Beam CT?
• Dental cone beam computed tomography (CBCT) is a special type of x-
ray machine used in situations where regular dental x-rays are not
sufficient. CBCT scanner generates three dimensional (3-D) images of
dental structures and soft tissues in a single scan.

11. How Does CBCT Work?
• CBCT Imaging is accomplished by using a rotating gantry to which an
x-ray source and detector are fixed.
• A divergent cone-shaped source of X-rays is directed through the
middle of the area of interest while the x-ray detector on the opposite
side.
• The x-ray source and detector rotate around a rotation pivot fixed
within the center of the region of interest. During the rotation,
multiple sequential two dimensional images (from 150 to more than
600) of the field of view (FOV) are acquired in a complete. Then,
these series of 2D images are reconstructed in 3Dimensions using a
specific computer program
• This technique allowed for great details and accurate diagnostic
information

12. X-Ray sourceDetector

14. Advantages of CBCT over Radiography
1- More efficient: Allows dentists to see the entire mouth not just a
small corner from an x-rays
2- More accurate: 3D CBCT imaging has better resolution, allowing for
highly accurate imaging and measuring. This means these images can
be used to pinpoint the exact location for a dental procedure.

15. disadvantages of CBCT over Radiography
1- More expensive
2-Longer scan time
3- The radiation dose received by the patient in CBCT is more than that
received by the same patient in radiography.
• The effective dose of the radiography is 1-5 µSv
• The effective dose of CBCT ranges from 18-135 μSv
• IN CBCT, the radiation dose received by the patient varies depending on
exposure time, tube current and potential, and the region of the jaw that is
undergoing the scan.
Due to the higher dose received by the patient, dentists should use CBCT
only in situations where regular dental x-rays are not sufficient.

16. References
• 1-Konik Işınlı Bilgisayarlı Tomografinin Temel Kavramları ve Dişhekimliğindeki Kullanım Alanları,
CONE BEAM COMPUTED TOMOGRAPHY: BASICS AND APPLICATIONS IN DENTISTRY, J Istanbul Univ
Fac Dent 2017;51(3 Suppl 1):
• 2- The Genesis and Development of CBCT for Dentistry, A Peer-Reviewed Publication Written by
James Mah, DDS, DMSc, MS, BSc
• 3- https://www.endopracticeus.com/ce-articles/benefits-limitations-cbct/
• 4- https://www.arizonafamilydental.com/blog/benefits-3d-dentistry-cbct-
machines/
• 5- http://madisondentalny.com/services-provided/imaging/computer-imaging/
• 6- https://deltadentalbc.com/portfolio-items/delta-x-rays/
• 7- https://en.wikipedia.org/wiki/Dental_radiography
• 8- https://www.revolvy.com/topic/Dental%20radiography&item_type=topic