Raida iii /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 ,or call

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Raida iii /certified fixed orthodontic courses by Indian dental academy

  1. 1. INDIAN DENTAL ACADEMY GOOD MORNING Leader in continuing dental education 1
  2. 2. What is a MRI scan? Is a radiological technique that uses magnetism, radio waves and a computer to produce images of body waves. 2
  3. 3. How does a MRI scanner work • Radio waves 10,000 – 30,000 times stronger than the magnetic field of earth are sent through the body. • Body produces radio waves of its own. • Scanner picks up these signals and a computer turns them into an image. 3
  4. 4. Magnetic Resonance Imaging A type of emission imaging Essentially imaging of water in the tissue 4
  5. 5. Magnetic Resonance Imaging Principle 5
  6. 6. Magnetic Resonance Imaging When images are displayed; intense signals show as white and weak ones as black. Intermediate as shades of gray. Cortical bone and teeth with low presence of hydrogen are poorly imaged and appear black. 6
  7. 7. Magnetic Resonance Imaging MRI can clearly differentiate the soft tissue components Preferred imaging technique when information regarding the articular disc or the presence of adhesions,or joint effusion is desired 7
  8. 8. How is an MRI scan performed? • Out patient procedure • Patient needs to relax. • All metallic objects need to be removed before the scan • Remove all hearing aids or pace makers. 8
  9. 9. MRI 9
  10. 10. Dental applications • Relation of orthodontics and TMD (Temperomandibular disorders). • Post treatment • Results of orthognathic surgeries. • Effects of mandibular advancements in obstructive sleep apnea. 10
  11. 11. Magnetic Resonance Imaging Indications Assessing diseases of the TMJ Cleft lip and palate Tonsillitis and adenoiditis Cysts and infections Tumors 11
  12. 12. Magnetic Resonance Imaging Contraindications  Patients with cardiac pacemakers.  Patients with cerebral metallic aneurysm clips. Slight movement of the clip could produce bleeding  Stainless steel and other metals produce artifacts ; obliterate image details of the facial area. 12
  13. 13. Magnetic Resonance Imaging Shortcomings  Inability to identify ligament tears or perforations  Dynamics of tissue joint not possible  Cannot be used in patients suffering from claustrophobia. 13
  14. 14. 3D Imaging Historical perspective 14
  15. 15. 3D Imaging Necessity - Our pts. are 3D therefore we need to record their morphology in 3D - Drawbacks of cephalometrics 2 dimensional representation of a 3 dimensional object 15
  16. 16. 3D Imaging With dimensionally accurate records, not only can t/t be planned and simulated,but implemented through methods such as computerized wire bending & fabrication of appliances by CAD/CAM Development of future technologies and approaches to Orthodontics 16
  17. 17. Basic principles of 3D imaging Two main geometrical strategies 1. Orthogonal measurement 2. Measurement by triangulation 1. Orthogonal – Location of 3rd dimension(z) by a technique separate from that used to measure the other two dimensions.(x & y) - Object sliced in layers – physically or optically 17
  18. 18. Basic principles of 3D imaging 2. Triangulation Images captured from two positions 18
  19. 19. Methods of 3D Facial Imaging LASER (Light Amplification by Stimulated Emission of Radiation) Structured light Laser scanner - Scanner record distortion of projected laser pattern on the face to provide a’ surface map’ 19
  20. 20. Methods of 3D Facial Imaging - Simultaneously image is recorded by a digital - camera This image is layered over the surface map 20
  21. 21. Methods of 3D Facial Imaging Structured Light - Projection of a structure of lines or grids onto the face - As the projected pattern is distorted by the contours of face, this distorted pattern is recorded by a digital camera 21
  22. 22. Obtaining 3D Dental Models Destructive scanning Non destructive scanning Destructive scanning - Variant of orthogonal slicing method - Study cast is invested in a solid matrix of contrasting colour -Surface of the block is then sliced parallel to the occlusal plane - Laser scan of the 2D surface is made - An additional 0.003” layer of the block is ground away and another scan is made 22
  23. 23. Obtaining 3D Dental Models Non destructive scanning - Laser stripe is projected on the surface of plaster cast and distortion pattern is recorded by a digital camera 23
  24. 24. 3D Craniofacial Skeletal Imaging Anatomic Reconstructions Computed Tomography Scans Cone Beam Computed Tomography 24
  25. 25. 3D Craniofacial Skeletal Imaging Anatomic Reconstructions (CRIL Method) - Integrated 3D model of the craniofacial structures is formed using lat.&fro. ceph; photographs & 3D models of dental casts. - Equipments – i. Calibrated stereo x ray device ii. Calibrated stereo camera iii. 3D models of study casts from Align Technology 25
  26. 26. • Step 1 – generating 3D dental models of upp & low teeth and creating Tiepoint bearing aligners - Tie points are reference points (like implants of Bjork) which facilitates merging of images 26
  27. 27. • Step 2 – placing facial Tie points • Step 3 – generating a 3D photographic model of the face 27
  28. 28. • Step 4 – generating a 3D x ray model of the craniofacial skeleton 28
  29. 29. • Step 5 - Merging the several 3D models - The CRIL software is used to merge the data in a single frame of reference - At least 3 common tie-points are required in each overlapping 29
  30. 30. • Step 6 – Viewing the integrated 3 Dimensional model The resulting 3D craniofacial model is viewed interactively using Align’s TREAT software 30
  31. 31. 3D Craniofacial Skeletal Imaging Computed Tomography Scans - Post processing software allows for reconstruction of transverse slices in any plane 31
  32. 32. 3D Craniofacial Skeletal Imaging Cone Beam Computed Tomography - Like conventional CT but various modifications are done to optimize them for craniofacial imaging - Reduced chamber volume just enough for head and neck - Real time feed back betn sensor and X ray source - Cone beam projection of x rays - Radiation exposure – 20%of conventional CT - Precision of 0.28mm which 5-10 times more 32
  33. 33. Softwares for Orthodontics • Many companies have developed softwares to help the Orthodontist in diagnosis and treatment planning - Dentofacial planner - Vistadent - Sure smile - Dr.Ceph - Digiceph - eModels - OrthoCAD 33
  34. 34. OrthoCAD Diagnosis Space analysis Treatment simulations- tooth movement,extn,occlusal contacts 34
  35. 35. Teleradiology • Teleradiology is the electronic transmission of radiological images from one location to another for the purposes of interpretation and/or consultation. • When a teleradiology system is used to produce the official authenticated written interpretation,- there should not be a significant loss of spatial or contrast resolution from image acquisition through transmission to final image display. 35
  36. 36. Electromyography 36
  37. 37. • Electromyography is defined as the recording and study of the intrinsic skeletal muscle by means of surface or needle electrodes . • Electromyography is the instrument used. • The structural basis of EMG is the motor unit. 37
  38. 38. Motor Unit Potential • During each twitch of the muscle fibre, a minute electrical potential is generated, which is dissipated into the surrounding tissues. • The duration may be there for 2 –3 millisecond or 4 millisecond. 38
  39. 39. • Majority of the motor unit potential have an • • amplitude of around 5mv. Einthoven first discovered a muscle contraction gives a idiomuscular current.This is referred to as an action potential.the current is so small that it has to be amplified several hundred times. Using electromyography one can get a relatively accurate picture of the muscle activity under diverse functional conditions. 39
  40. 40. Technique • Two types of electrodes are mainly used – • Surface electrodes ( skin) • Needle electrodes 40
  41. 41. Needle electrode • Superior to surface electrodes and produce • • • better Electromyograms. Lesser technical artifacts Distance between muscle and electrode is constant May cause infection and is painful 41
  42. 42. Surface electrodes • non invasive and reduced risk of infection • Possibility of loosening of electrodes while • nerve stimulation. Errors in variation between distance of muscle an electrodes 42
  43. 43. 43
  44. 44. Drawbacks • Impossible to know how much activity of the muscle being missed. • Movement cannot be inferred from electromyography alone, because antagonistic muscles may be working synergistically to produce movement or provide stabilization. 44
  45. 45. Electromyography in orthodontics • Muscles of importance ( figure ) 45
  46. 46. EMG activity in class II div 1 • Graber points out – class I -normal muscle activity (except open bite ) class II div 1 – abnormal muscle activity class II div 2 – compensatory muscle activity. 46
  47. 47. Electromyographic activity during swallowing • Winders et al (Angle Orthod) buccal and lingual musculature do not contract during swallowing unless there is an anterior open bite and anterior skeletal dysplasia. • In tongue thrust habit there is increase in genioglossus activity and hypertrophy of the tongue muscles (EMG activity increases during hypertrophy). 47
  48. 48. Cine Radiography • This is a basically a radiographic motion picture. • Cine camera-240frames/sec. • It is used to visualize the swallowing pattern. 48
  49. 49. Occlusograms • It is a tracing of photograph or photocopy of dental arch. • Uses. 49
  50. 50. 50
  51. 51. 51
  52. 52. Holography • It is a photographic technique for recording and reconstructing images in such a way that 3D objects can be obtained. • The recorded images are called Holograms. • Orthodontic applications of holography includes: 52
  53. 53. CONCLUSION Accurate patient’s record and reliable informations are key to our understanding of orthodontics. The goal would be to develop methods with which clinicians can accurately simulate treatment scenarious and select optimal biomechanics for the treatment of patients. The patient’s records ( photographs, radiographs and study models) has not changed for decades despite of its limitations. Newer approaches will allow objectives to review and investigate the clinical diagnosis and treatments based on 2D record. 53
  54. 54. References • T M Graber,Vanarsdall R L : Orthodontics• • • • • Current Principles and Techniques. Jacobson : Radiographic Cephalometry Goaz,White : Oral Radiology – Principles and Interpretation. Harring J I, Jansen L : Dental RadiographyPrinciples and Techniques Pasler F A : Colour Atlas of Radiology. Kapila & others : Craniofacial Imaging in Orthodontics : Historical Perspective,current status,and future developments. Angle Orthod, 1999; 69:491-506 54
  55. 55. • J J Menig. The DenOptix Digital Radiographic System. JCO,1999; 33: 407-410. • Seminars in Orthodontics, December 2001,Vol 7 No 4 : 1. Baumrind, Boyd : Integrated Three Dimensional Craniofacial Mapping: Background,Principles and Perspectives 2. Hans et al : Three Dimensional Imaging : The Case Western Reserve University Method. 3. O C Tuncay: Three Dimensional Imaging and Motion Animation 4. J Mah, A Bunman: Technology to create Three Dimensional Pt. Record. 5.Curry,Baumrind : Integrated Three Dimensional Craniofacial Mapping at the Craniofacial Research Instrumentation Laboratory/University of the Pacific. 6. W R Redmond : The Digital Orthodontic Office:2001. 55
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