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

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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 www.indiandentalacademy.com ,or call
0091-9248678078

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  • 1. RECENT ADVANCES IN DIAGNOSTIC AIDS INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  • 2. Specialized radiographic techniques www.indiandentalacademy.com
  • 3. • • • • Digital subtraction radiography Xeroradiography Ultrasonography Laser holography www.indiandentalacademy.com
  • 4. Digital subtraction radiography www.indiandentalacademy.com
  • 5. • Requires two different images and the subtracted image is a composite of these two images representing their different densities www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 8. www.indiandentalacademy.com
  • 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 www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 13. www.indiandentalacademy.com
  • 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 www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 17. • Computer can be used to correct distortion caused by film placement • Reference points can be used to superimpose sequential radiographs. www.indiandentalacademy.com
  • 18. Applications • Useful in diagnosis of periodontal and carious lesions. (both of which are characterized by insidious and slow rate of resorption). www.indiandentalacademy.com
  • 19. Applications • Used for quantitative estimation of mass or volume of a lesion. measurement can be measured with the help of a wedge. www.indiandentalacademy.com
  • 20. • Contrast enhancement with image in color can detect small change in bone. www.indiandentalacademy.com
  • 21. • Useful in detection of small changes in mandibular condyle position and integrity of articular surfaces and or remodeling around granular hydroxyapatite implants. www.indiandentalacademy.com
  • 22. • Assessment of failure of implant therapy and progress of periodontal therapy. www.indiandentalacademy.com
  • 23. Image enhancement of mandibular condyle through digital subtraction • OOO 1987 ( south had et al ) www.indiandentalacademy.com
  • 24. Radiographic evaluation of the effect of orthodontic retraction on the root of the maxillary canine • Perona and wenzel (dentomaxillofacial radiology 1996) www.indiandentalacademy.com
  • 25. Digital subtraction radiography for assessing alveolar bone grafts:diagnostic accuracy and sensitivity • Maruko and Forbes ( 1993 ) www.indiandentalacademy.com
  • 26. Ultrasonography www.indiandentalacademy.com
  • 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 www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 29. www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 32. www.indiandentalacademy.com
  • 33. • Slice thickness of 0.5 mm or less. • Real time imaging. • Here image is produced by reflected portion of the beam www.indiandentalacademy.com
  • 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). www.indiandentalacademy.com
  • 35. Applications • Imaging of the – lymph nodes www.indiandentalacademy.com
  • 36. Applications • Imaging of the – thyroid gland www.indiandentalacademy.com
  • 37. Applications • Imaging of the – salivary glands www.indiandentalacademy.com
  • 38. Applications Post surgical oedema and haematoma Thickness of the masticatory mucosa Displacement of soft tissue under forces of occlusion www.indiandentalacademy.com
  • 39. Comparative data on facial morphology and muscle thickness using ultrasonography • Fiikreet et al( EJO 2005) www.indiandentalacademy.com
  • 40. Xeroradiography www.indiandentalacademy.com
  • 41. • New method for recording images without film. • based on an electrostatic process (similar to those used in paper copiers) www.indiandentalacademy.com
  • 42. Types of systems • Medical 125 system (since 1970s) • Dental 110 system (recently developed) www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 45. Figure of process www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 47. www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 49. www.indiandentalacademy.com
  • 50. www.indiandentalacademy.com
  • 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) www.indiandentalacademy.com
  • 52. Applications • • • • Mammography Cephalometrty Sialography Detection of caries and alveolar bone height ( progress of periodontal diseases). • Detection of oral cancer • Imaging of bio materials. www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 54. www.indiandentalacademy.com
  • 55. The role of xeroradiography in cephalometry • Davis et al (Journal dent 1977) www.indiandentalacademy.com
  • 56. Radiologic exposure conditions And resultant skin doses in application of xeroradiography to orthodontic diagnosis • Nakasima et al (AJO DO 1980) www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 58. Laser holography www.indiandentalacademy.com
  • 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 ) www.indiandentalacademy.com
  • 60. Holography • Holos means whole • Gramma means message • An advanced form of photography, allows an image to be recorded in dimensions. www.indiandentalacademy.com 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). www.indiandentalacademy.com
  • 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 . www.indiandentalacademy.com
  • 63. Two types of lasers • Helium neon laser www.indiandentalacademy.com
  • 64. Two types of lasers • Pulse ruby laser www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 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 www.indiandentalacademy.com
  • 68. Types of holograms • Reflection hologram - most common type seen in galleries • Transmission hologram - visa card www.indiandentalacademy.com
  • 69. Holography in medicine www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 71. Multiplexed holography • Complete display of 3d tomographic medical data. • Used in prostheses and craniofacial surgery . • Volumetric multiplexed holograms. www.indiandentalacademy.com
  • 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. www.indiandentalacademy.com
  • 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 ) www.indiandentalacademy.com
  • 74. Holographic determination of the centre of rotation produced by orthodontic forces • Burstone et al (AJO – DO 1980) www.indiandentalacademy.com
  • 75. Specialized radiographic techniques Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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