Your SlideShare is downloading. ×
Specialized radiographic techniques /certified fixed orthodontic courses by Indian dental academy
Upcoming SlideShare
Loading in...5

Thanks for flagging this SlideShare!

Oops! An error has occurred.

Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Specialized radiographic techniques /certified fixed orthodontic courses by Indian dental academy


Published on

The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit ,or call

Published in: Education
  • Be the first to comment

  • Be the first to like this

No Downloads
Total Views
On Slideshare
From Embeds
Number of Embeds
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

No notes for slide


  • 1. RECENT ADVANCES IN DIAGNOSTIC AIDS INDIAN DENTAL ACADEMY Leader in continuing dental education
  • 2. Specialized radiographic techniques
  • 3. • • • • Digital subtraction radiography Xeroradiography Ultrasonography Laser holography
  • 4. Digital subtraction radiography
  • 5. • Requires two different images and the subtracted image is a composite of these two images representing their different densities
  • 6. • Sensitive enough to detect a .12 mm change in the cortical bone. • The ability of this technique to detect minute changes is dependant on the degree of matching of the two images.
  • 7. Technique • In DSR two standardized radiographs of anatomical region are made with identical exposure geometry at different time period. • The first radiograph is considered a reference image while the second radiograph taken at a later date is the image to be compared.
  • 8.
  • 9. • The first reference image is digitized and converted to a exact positive image by the computer and displayed on the TV screen as a positive image. • Then the second image is superimposed on the positive reference image
  • 10. • Any differences between the two images will be shown on neutral gray background as brighter or darker areas depending on the nature of tissue changes.
  • 11. • By this process a radiograph is converted to an array of points each of which has a specific optical density. • If each points of identical images is subtracted the result will be a neutral gray image.
  • 12. • In clinical practice the two radiographs are taken one after he other ,after some time presuming some tissue changes have occurred • In DSR the changes otherwise not clinically visible are seen with subtle change in the densities of the two radiographs.
  • 13.
  • 14. Procedure • Digitization • To digitize a picture is taken using a video camera • Then computer digitizers place a grid over the radiograph and convert the continuous gray scale to different numbers between 0 –255
  • 15. Limitations • Diagnostic information can only be obtained when orientation of the x ray source,object and the image receptor is highly repeatable. • Subtracted image must be of the identical anatomical region. • Density and contrast of the original image should not effect that of the resulting image.
  • 16. Overcoming the limitations • Computer algorithms have been developed for overcoming the variation in density and contrast. • The occlusal stants can be used to stabilize relationships between teeth film and x ray source. • Cephalostat can be used to stabilize x ray films and the teeth.
  • 17. • Computer can be used to correct distortion caused by film placement • Reference points can be used to superimpose sequential radiographs.
  • 18. Applications • Useful in diagnosis of periodontal and carious lesions. (both of which are characterized by insidious and slow rate of resorption).
  • 19. Applications • Used for quantitative estimation of mass or volume of a lesion. measurement can be measured with the help of a wedge.
  • 20. • Contrast enhancement with image in color can detect small change in bone.
  • 21. • Useful in detection of small changes in mandibular condyle position and integrity of articular surfaces and or remodeling around granular hydroxyapatite implants.
  • 22. • Assessment of failure of implant therapy and progress of periodontal therapy.
  • 23. Image enhancement of mandibular condyle through digital subtraction • OOO 1987 ( south had et al )
  • 24. Radiographic evaluation of the effect of orthodontic retraction on the root of the maxillary canine • Perona and wenzel (dentomaxillofacial radiology 1996)
  • 25. Digital subtraction radiography for assessing alveolar bone grafts:diagnostic accuracy and sensitivity • Maruko and Forbes ( 1993 )
  • 26. Ultrasonography
  • 27. • By definition ultra sound has a periodicity of greater than 20 kHz • It is distinguished from other wave forms simply having a vibratory frequency greater than the audible range. • Diagnostic ultrasonography, the clinical application of ultrasound uses wave on the frequencies of 1 to 20 MHz
  • 28. How they work • Scanners used for sonography generate electrical impulses that are converted to high frequency sound waves by a transducer. • The transducer consists of a thin piezo electric crystal or material made up of great number of dipoles arranged in a geometric pattern.
  • 29.
  • 30. • Most commonly used piezoelectric crystal is lead zirconate. • The electrical impulse generated by scanner causes dipoles within the crystal to realign themselves in the electric field . • This causes a change in the thickness which releases a series of vibrations that produces sound waves.
  • 31. • An ultra sound beam passes through or interacts with the tissues of different acoustic impedance,it is accentuated by a combination of absorption, reflection, refraction and diffusion. • Sonic waves that are reflected back to the transducer cause a change in thickness of piezoelectric crystal, which in turn produces a signal which is processed and displayed on a monitor.
  • 32.
  • 33. • Slice thickness of 0.5 mm or less. • Real time imaging. • Here image is produced by reflected portion of the beam
  • 34. • The fraction of beam that is reflected back depends on the acoustic impedance of the tissue and is characteristic for different tissues. (internal echo pattern).
  • 35. Applications • Imaging of the – lymph nodes
  • 36. Applications • Imaging of the – thyroid gland
  • 37. Applications • Imaging of the – salivary glands
  • 38. Applications Post surgical oedema and haematoma Thickness of the masticatory mucosa Displacement of soft tissue under forces of occlusion
  • 39. Comparative data on facial morphology and muscle thickness using ultrasonography • Fiikreet et al( EJO 2005)
  • 40. Xeroradiography
  • 41. • New method for recording images without film. • based on an electrostatic process (similar to those used in paper copiers)
  • 42. Types of systems • Medical 125 system (since 1970s) • Dental 110 system (recently developed)
  • 43. How they work • Image is recorded on a selenium coated plate. • Selenium plate given an electrostatic charge in a conditioner. • Then the plate is exposed and the x-rays penetrate the body parts and strike the plate causing an electrical discharge.
  • 44. • The amount it discharges equals to the amount of radiation striking the receptor. • The patter of electrical charge is referred to as a latent image. • This is converted to visible image by a process called development.
  • 45. Figure of process
  • 46. Development • The plate is exposed to a cloud of charged powder particles called as toner. • Individual toner particles are attracted to surface of the plate . • The association of the toner and plate is related to the distribution of the charge and is controlled by electric fields.
  • 47.
  • 48. Dental 110 system • Similar to the medical 125 system in concept is physically different. • The plates are of 1 and 2 size and fit conveniently into the oral cavity. • The plates are charge and developed in a single piece of equipment.
  • 49.
  • 50.
  • 51. Advantages • Edge enhancement (deposition of more toner to the high charge side of the boundary and less toner on the low charge side ) • A choice of positive and negative displays • Good detail • Wide exposure of latitude. (imaging of objects of broad range of densities in a single exposure)
  • 52. Applications • • • • Mammography Cephalometrty Sialography Detection of caries and alveolar bone height ( progress of periodontal diseases). • Detection of oral cancer • Imaging of bio materials.
  • 53. TMJ tomography • Bony margins are see in more detail and sharply. • Halender et al and Castrup and Shwatz showed no significant difference between tomographic images and xeroradiographs.
  • 54.
  • 55. The role of xeroradiography in cephalometry • Davis et al (Journal dent 1977)
  • 56. Radiologic exposure conditions And resultant skin doses in application of xeroradiography to orthodontic diagnosis • Nakasima et al (AJO DO 1980)
  • 57. Conventional radiography vs. xeroradiography • Edge enhancement and wide latitude • Greater ability to resolve structures • Greater visualization of minute details of bone and teeth. • Require about one third exposure of conventional film.
  • 58. Laser holography
  • 59. Laser • Light amplification by stimulated emission of radiation. • Coherence is the key property. (means all the waves of light are going up and down together )
  • 60. Holography • Holos means whole • Gramma means message • An advanced form of photography, allows an image to be recorded in dimensions. 3
  • 61. History • Denis Gabor – 1947 (Hungarian physicist). • Not until laser holography was so popular. (conventional light sources gave too little light or too much light).
  • 62. Lasers how they work • Depends of certain characteristics of certain atoms which have been raised to an excited state,which when brought back to ground state release a package of electromagnetic radiation .
  • 63. Two types of lasers • Helium neon laser
  • 64. Two types of lasers • Pulse ruby laser
  • 65. Holography basics • Two step lens less imaging process called as wavefront construction. • An interference between the object field and background wave (reference wave) is formed and recorded with photographic material. • The aim is to record both amplitude and phase.
  • 66. • The record known as hologram captures the complete wave which can be viewed at later date with appropriate illumination. • The object can be considered to be made up of a number of point sources distributed in 3 dimensions.
  • 67. • Because of need for interference between the reference and object beams, holograms typically need a laser to produce them • The light from laser produces two beams one is the reference beam and the other illuminating the object called as object beam
  • 68. Types of holograms • Reflection hologram - most common type seen in galleries • Transmission hologram - visa card
  • 69. Holography in medicine
  • 70. X ray holography • Imaging of internal body parts of the body and living biological specimens with very high resolution without the need for sample preparation.
  • 71. Multiplexed holography • Complete display of 3d tomographic medical data. • Used in prostheses and craniofacial surgery . • Volumetric multiplexed holograms.
  • 72. Endoscopic holography • Potential for providing a powerful tool for non contact high resolution 3d imaging and non destructive measurements inside natural cavities of human body or in any difficult to access environment.
  • 73. Orthodontic applications • Holographic study of variations in bone deformations resulting from different head gear forces in a macerated human skull (Andrej Zetner – AO 1995 )
  • 74. Holographic determination of the centre of rotation produced by orthodontic forces • Burstone et al (AJO – DO 1980)
  • 75. Specialized radiographic techniques Thank you For more details please visit