When high primary stability is achieved, immediate and early loading protocols have been reported safe and successful in the scientific literature.
In this section, you will find summaries on documentation of immediate and early loading using the Astra Tech Implant System'".
Implant rehabilitation of the atrophic edentulous maxilla including immediate fixed provisional restoration without the use of bone grafting: A review of 1 -year outcome data from a long-term prospective clinical trial
The immediate restoration of implants placed into the edentulous maxilla has received some attention with the literature providing supporting evidence for high success/survival outcomes as measured by implants retained in function over the short-term. However there is still a need for further study in this area particularly for treatment of the atrophic maxilla where low bone volume and density might result in a compromised outcome.
Purpose: This study therefore set out to monitor the success/survival of implants placed into atrophic maxillae and subject to immediate restoration as part of a long-term prospective study.
Materials and Methods: Twenty-four men and 27 women with atrophic edentulous maxillae scored as c, D or E according to the Lekholm & Zarb classification and with a bone quality scored as either 3 or 4 were consecutively enrolled to the study in two dif-ferent centers. Selected implant sites had to be capable of receiving at least an 8 mm X 3.5 mm implant without the need for bone grafting. Patients who had uncontrolled disease either locally or systemically or who smoked were excluded as were any patients who had received earlier bone grafting procedures.
All patients were treatment planned to receive 6 OsseoSpeed™ (Astra Tech) implants placed via a conventional approach. The drilling protocol was adjusted to allow for low density bone, resulting in under-preparation where necessary, so the self tapping implants could attain a higher degree of primary stability. When necessary the most distal implants were angulated to avoid any breach into the sinus cavities. Where buccal dehiscences occurred, exposing threads, no action was taken to cover the threads since grafting was not part of the study protocol. Straight or angulated abutments were connected at time of surgery and appropriate copings secured to them prior to repositioning of the flaps for suturing. Screw-retained prostheses were fabricated by either a direct or indirect technique. For the former, the patient's own existing denture was trimmed, hollowed and relined in situ over the copings to allow a direct pick-up. For prostheses fabricated via the indirect route, an abutment level impression was taken and a previously prepared tooth set-up was located to the master cast and processed around the copings. Prostheses were finished according to standard techniques. All prostheses were delivered within 24 hours.
Data on implant dimensions, site location, bone density and volume were all recorded as was primary stability measured by peak insertion torque values (PIT, Ncm). Standardized radiographs were taken using a paralleling device to measure the bone level under x7 magnification and to the nearest 0.1 mm relative to the bevel at the top of the implant. At 12 weeks post-op all restorations were removed to allow the fabrication of the definitive prostheses. At this time implants were individually assessed for osseointegration and radiographs taken. Definitive prostheses were inserted approximately 22 weeks after surgery when another set of radiographs were taken. At 12-months post-op patients were once again recalled for removal of prostheses to allow direct implant assessment and for additional radiographic evaluation.
Results: A total of 306 implants were inserted into bone which was relatively evenly classified between categories c & D and between qualities 3 and 4. PIT values ranged from <10 to >45 Ncm (50% 0 -25 Ncm). 25 patients were provisionalized via the direct method. There was 1 patient drop-out and a total of 12 implants (5 patients) were deemed failures within the 12-week provisional period (4%). At time of definitive prosthesis placement there was a mean bone loss of 0.5 mm +/- 0.7 mm with no additional bone loss noted at the 1-year recall. No single parameter could be identified as being associated with the failures.
Discussion and Conclusion: The data from this 1-year interim report would seem to suggest that even implants placed into the atrophic maxilla without the use of any bone grafting can be successfully restored and placed into immediate functional loading, with survival data and marginal bone loss data being comparable to that reported elsewhere. This may present a more appealing treatment strategy to patients with little apparent additional risk.
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