Long‐term Bone Stability in “all on Four Flat Technique”

Background Patients with atrophic mandible could be rehabilitated with ‘All on four’ technique that has been described in literature like a good cost-effective therapeutic option that allowed to decrease morbidity and time of treatment. The placement of two tilted intraforaminal implant (in addiction to axial ones) enables possible the extension of rehabilitation until posterior sectors without an excessive cantilever length. However tilted implants could show a greater bone reabsorption during time. Aim/Hypothesis We had studied long-term bone stability in ‘all on four flat rehabilitation’ with a particular connection – a flat between implants and prostheses. The aim is to evaluate the bone reabsorption around 132 implants with an average follow-up of 57 month (since 2007 to 2015). Material and Methods With an amount of 45 cases we had studied 33 patients because of their similar clinical and surgical approaches – open flap, osteoplastic to regularize crest, placement of 4 implants (two axial and two tilted at 45°) Intralock DT sti 40 × 10 and 40 × 13. All patients received a provisional prostheses without any cantilever. A TC has been done before surgery to evaluate the amount of bone in intraforaminal section. To evaluate the bone resorption around implants has been done a series of periapical radiograph. The reference point for the measurements has been calculated with the distance between the bone level and the implant platform. For each implants has been choose a single measurement of the side were the resorption was greater. All radiographs have been calibrated with implant's length. The statistic average has been identify for all measurements that was found. Results The cumulative implants survival was 100%. The average marginal bone loss was 1.7 mm during an average follow-up of 57 month. 4 implants showed a marginal bone loss of 3–3.2 mm. The successful percentages was 94% because 128 implants have had a physiological bone reabsorption according to the literature. The implants that showed a greater reabsorption of marginal bone were 6%. However, even though the reabsorption was greater this cannot compromise the stability of the implants. Conclusions and Clinical Implications Analysing the results we can conclude that the bone reabsorption is acceptable according to the literature. The flat abutment allows obtain a passive prosthetic structure on tilted implants. The masticatory force goes parallel to the implant and avoids transversal loads which are dangerous, because they generate bone resorption around implants. Therefore this can increase the survival of implants and the long-term bone stability in this rehabilitation.