A 3-year retrospective study of Cresco frameworks: preload and complications

The aim of this retrospective clinical study was to evaluate the clinical outcome of fixed implant-supported complete prostheses on Astra or Brånemark implants when using either conventional cast frameworks or frameworks produced according to the Cresco Ti Precision method (Cresco Ti Systems Sàrl., Lausanne, Switzerland).

Forty-six patients treated 3 years previously were divided into four groups according to implant system and framework design. Clinical examinations were performed and case records were scrutinized. The stability for each prosthesis retention screw was recorded as the torque profile and was monitored using the Osseocare torque controller (Nobel Biocare AB, Göteborg, Sweden). Complications in association with implants and superstructures were registered. Patient opinions were recorded. The significance level was set to 5%.

The Astra-Cresco group demonstrated a lower degree of prosthesis retention screw stability compared with the Astra group. No differences among the four groups were seen regarding plaque, bleeding on probing, or marginal bone resorption. The Brånemark group (Brånemark System, Nobel Biocare AB) demonstrated more mechanical complications than the Brånemark-Cresco group. Mobile prostheses were found in the Brånemark and the Astra-Cresco groups. Fracture of veneer was seen in 20% of the prostheses and was more frequently found in the groups with mobile prostheses. Sixty percent of the prostheses showed reactions in the surrounding soft tissues. The most common reaction was mucosal proliferation. No differences were detected in the patients' opinions.

Within the limitations of this retrospective study, the following can be concluded: (1) compared with conventional frameworks, the Cresco distortion correction method does not provide a better clinical outcome after prosthesis connection in patients with fixed implant-supported complete prostheses; and (2) the two framework-producing methods behave differently on Astra implants compared with Brånemark implants concerning prosthesis retention screw stability, mechanical and biologic complications, and reactions in patients with fixed implant-supported complete prostheses.