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Surgery and
Restoration of Posterior Maxillary Quadrant using ITI®
Implants Since Tatum in 1976 first developed the sinus elevation procedure, there have been many advances in the technique. Yet only recently are we beginning to understand the after-effects of allographic placement. Schenk et. al. has shown in beagle dogs that FDDB is maintained for many months, perhaps indefinitely. This case report shows the use of an 8 mm. ITI hollow screw implant as a posterior abutment in lieu of the sinus surgery. A sixty year old man in good health reported with chief complaint of missing teeth. Radiologic evaluation revealed missing teeth #s 13 and 14. #15 was present with hopeless prognosis. Adequate bone height was available in the first premolar region with only about 8 mm present in the first molar area. Bone mapping technique showed a 5 mm crestal width.
Rather than the more invasive sinus elevation procedure, it was decided to use an 8 mm. hollow screw fixture. The advantages are that the inner core utilizes more bony interface, the screw thread pitch is designed for maximum fixation, and of course less traumatic surgery. The disadvantages are that the hollow implant has less strength than the solid body screw of the same manufacturer and that sinus penetration is contraindicated. The first step in the procedure is the diagnostic wax-up. This will be the basis for all future surgical and restorative procedures. A surgical template is fabricated using the remaining teeth as a positive seating area. The design should be based on the preference of the surgeon, using clear rigid materials in an unobtrusive manner.
A mid-crestal incision slightly to the palatal is laid. A bone measuring caliper is used, as it is important the implant is entirely housed in bone. The surgical quide is the placed and adjusted. The round marker drills can now be used to start the osteotomy.
The implants should be no closer than 7 mm center to center and should be checked for proximity to the remaining teeth. A common error early in the learning curve is the placement of the premolar implant too far distally, resulting in ensuing prosthetic gymnastics. It is important however not to nick the adjacent tooth as dentin is not known to integrate implants. If the guide markers are satisfactory, then the pre-drill can be used in conjunction with the surgical guide because the occlusal plane position still dictates the buccal-palatal implant angulation. Counter- sinking, if needed is then accomplished. In this case only the premolar was countersunk as the molar implant needed all available bone. The final drilling is done with the use of internally cooled trephines.It is important to note countersinking and adjust depth accordingly. This is done with the depth gauge. Since the maxillary bone was relatively soft it was decided to place the implants in a self tapping fashion.
Closure was obtained using horizontal mattress and interrupted sutures. A surgicel dressing was also used for patient comfort. The post operative radiograph revealed satisfactory implant placement.
The one week postoperative visit showed uneventful healing as often is the case for one stage implants.
Prosthetic work commenced four months after placement, using the solid body posts for cement retention. The same diagnostic wax-up that was used in template fabrication now can be used for the provisionals.
After extraction of
#15, a larger molar crown was used in the final
prosthesis. |
