Orofacial implant

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Radiology II
Forth Year

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Orofacial implant

  1. 1. Oro-facial implants By Dr. Hassan M. Abouelkheir BDS, MSC, PhD.
  2. 2. Ideal image casting: • The ability to visualize implant site buccolingually, mesio-distally & superio- inferiorly. • The ability to allow reliable accurate measurements. • The capacity to evaluate trabecular density & cortical thickness. • The capacity to correlate the imaged site with clinical site. • Reasonable access & cost to patient. • Low radiation dose.
  3. 3. Intra-oral Radiography • 1- Periapical Radiographs: • It Provide superior resolution and sharpness. • Parallel technique is used to decrease geometric errors. • They determine vertical height, architecture and bone quality (bone density, amount of cortical & trabecular bone. !
  4. 4. Intra-oral Radiography (continue): • Geometric & anatomical limitations: • Foreshortening & elongation of radiographic alveolar height. • Positioning of film may miss anatomical structures. • Unable to provide any cross- sectional information.
  5. 5. 2- Occlusal radiographs: • Although it gives a clue about facio- lingual dimension of mandibular alveolar ridge . • It records the widest portion of the mandible which is below the alveolar ridge . • It is not suitable for maxilary arch due to anatomical limitations. Intra-oral Radiography (continue):
  6. 6. Extra-oral radiographs: • 1- Lateral & Lateral-oblique cephalometric radiography: ! • Lateral cephalometric: has 7% to 12% magnification It gives the axial tooth inclination and dento - alveolar relationships as well as cross section at midline only due to over projection of the lateral areas of the jaw.
  7. 7. Extra-oral radiographs (continue) 2-Oblique Lateral Cephalometric Radiographs (OLCR) • One side of the body of the mandible positioned parallel to the film cassette. • A cephalostat with earplugs and a nasion support was used to position the head with the porion-subnasal plane in a horizontal position. A light beam was used to position the mandibular lower border with an inclination of 20 degrees. • Measurements from this image are not reliable.
  8. 8. Extra-oral radiographs (continue): ! 3- Panoramic radiography: • It is important for broad visualization of the jaws and anatomical structures. • It is useful for preliminary estimations of crestal alveolar bone and cortical boundaries of ID canal, max. s. & nasal fossa.
  9. 9. Limitations of panoramic radiography: 1- angular measurements are accurate but horizontal ones are not. 2 - Magnification (size distortion) varies among films from different panoramic unites and also at different areas on the same film. 3- Foreshortening and elongation of vertical measurements. 4- Overestimation of vertical bone heights. 5- Magnification of horizontal image measurements as a result focal trough area constructed on average population (0.70 to 2.2 times actual size) .
  10. 10. 4- conventional tomography: • This technique produces a cross –sectional , flat-plane image layer that is perpendicular to the x-ray beam. • The complex (multidirectional) tube motion of current conventional tomographic units minimizes image superimposition & provide fixed uniform image magnification for accurate measurements.
  11. 11. • Radiographic stents are used to determine the width and height of pre-planned implants after correction with magnification factor as in case of using scanora integrated imaging system. • Two or three cross-sectional tomographic slices are required to preplan each intended implant site.
  12. 12. 5- Reformatted computed Tomography: It is indicated for : 1- Edentulous pts. 2- Multiple implants. 3- Augmentation procedures. 30 axial images are required per jaw (1-2mm). These sequential axis images can be manipulated by process called multiplannar reformatting (MPR) to produce multiple two dimensional images in various planes.
  13. 13. Reformatted computed Tomography (cont.) • The CT analysis comes from 3 basic image types: • Axial images. • Reformatted cross-sectional images. • Panoramic like images. • The computer places a series of sequential dots on selected scan then connect them to construct a customized arch . • Then it places a series of lines at constant intervals (1-2mm) on axial image to indicate the position at which each cross sectional slice will be reconstructed.
  14. 14. Reformatted computed Tomography (cont.) • These reformatted images provide the clinician with two- dimensional diagnostic information in all three dimensions. • It gives information on; 1- amount of cortical bone and residual bone. 2- location of vital structures. 3- contour of soft tissues. 4- 3D reformations for augmentation as in maxillary sinus lifting.
  15. 15. Pre-operative planning: • Diagnostic image can give 3D information about quality and quantity of alveolar bone. Quality: • 1- the thicker the cortical bone the best withstand for functional load. • 2- A greater number of internal trabeculae per unit area is advantageous.
  16. 16. Pre-operative planning (cont.): Quantity: 1- Height . 2- Width of alveolar bone. 3- Morphology of ridge. Cross –sectional image to determine facio- lingual width and height , along with inclination of bone contour.
  17. 17. Pre-operative planning (cont.): • Pre-planning measurements in different technique shows variable magnification factor (MF). • Radiographic image / MF to correct measurements. • (Pan, Periapical).
  18. 18. Pre-operative planning (cont.): • If MF is constant a plastic overlay with 1mm grids or diagrams of available implant sizes can be used directly on image. • Specialized reformatted CT implant programs can perform image without magnification. It can be printed life size.
  19. 19. Imaging stent • Pre-surgical imaging can be enhanced by radiographic stent to locate the position of pre-surgical site for end osseous implant. • The intended implant sites are identified by radiopaque spheres or rods (metal, composite resin or Gutta percha).
  20. 20. Interactive Diagnostic software: several interactive software packages (e.g. Sim-plant ) allow presurgical simulation of implant orientation and placement.
  21. 21. Interactive Diagnostic software: • There are 3 basic views available on the Sim/Plant™ screen: • The Panoramic view is similar to a normal two dimensional panoramic view. • The axial view offers a perspective from a coronal/ apical direction. • There is a cross sectional view that allows a mesial /distal cross sectional perspective of the arch.
  22. 22. Selecting diagnostic imaging for pre- operative planning: 1- panoramic view. 2- intraoral periapical films for particular region of interest. 3- CT if entire maxilla or/and mandible is required. 4- conventional tomography for few selected regions.
  23. 23. Intra-operative & postoperative assessments: 1- panoramic view. 2- intraoral radiographs. • Intra- operative films may be required for confirmation of correct implant placement or to locate a lost implant. • Inspection includes; 1- alveolar bone height around implant. 2- the appearance of bone around and adjacent to implant.
  24. 24. Intra-operative & postoperative assessments • Angulations of x-ray beam must be within 9 degrees of long axis of the fixture to see the sharp image of threads of fixuture . • Otherwise angular deviation of 13 degrees or more result in complete overlap to the threads.
  25. 25. Intra-operative & postoperative assessments • Longitudinal assessment of implant by serial standardized periapical films using XCP- film holder with rubber base impression material to measure; 1- Mesial & Distal bone height from standard landmark at the collar of implant. 2- or interthread measurements compared to bone levels on serial radiographs.
  26. 26. Intra-operative & postoperative assessments • There is initial circumscribed resorptive osseous changes around cervical area of fixture during 1st 6 months after surgery. • It was estimated that there was marginal bone loss 1.2mm in the 1st year then 0.1mm in succeeding years.
  27. 27. Intra-operative & postoperative assessments • If any resorptive changes are present , they evidenced by apical migration of the alveolar bone or indistinct osseous margins. • Density can be measured in intraoral digital radiographs to measure bone resorption .
  28. 28. Intra-operative & postoperative assessments • Digital subtraction radiography requires image geometry reproduction between radiographic examinations. • The success of implant can be evaluated by normal bone surrounding and up to the surface of the implant . • No clinical mobility.
  29. 29. Radiographic signs of failing endosseous implants: • Thin radiolucent area surrounding the entire implant. • Crestal bone loss around the coronal portion of the implant. • Apical migration of alveolar bone on one side of the implant. • Widening of PDL space of nearest natural Tooth (abutment). • Fracture of implant fixture.

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