Immediate loading of fixed provisional prostheses using four implants for the rehabilitation of the edentulous arch: a prospective clinical study.

PURPOSE: The purpose of this prospective clinical trial was to evaluate over a 5-year period the treatment outcomes for immediately loaded full-arch fixed prostheses supported by two axially inclined and two tilted implants used to rehabilitate edentulous arches. This report presents preliminary 1-year results.
MATERIALS AND METHODS: Thirty-seven patients were recruited for treatment with either mandibular or maxillary full-arch fixed prostheses supported by four implants. Within 24 hours, the implants were immediately loaded with screw-retained full-arch acrylic resin provisional restorations. Definitive reconstructions were delivered 6 months later. Complete full-arch prostheses were supported by metal frameworks combined with high-density acrylic resin. Follow-up visits were scheduled for 6 and 12 months after initial prosthetic loading and then annually for up to 5 years. Digital radiographs were obtained immediately, 6 months after surgery, and at each annual follow-up visit. Marginal peri-implant bone levels were assessed using digital image analysis.
RESULTS: The 1-year implant survival rates were 96.0% for axially positioned implants and 94.6% for tilted implants. The survival rates were 96.6% for maxillary implants and 98.7% for mandibular implants. The prosthetic survival rate was 100%. No significant differences were found in the results for tilted versus axially positioned implants. One year after loading, the mean marginal bone loss was 0.82 ± 0.31 mm around the axially oriented implants and 0.76 ± 0.49 mm around the tilted implants (P ⋜ .05).
CONCLUSIONS: Preliminary data from this clinical trial show high implant survival rates for immediately loaded full-arch prostheses supported by four implants. Immediate loading of tilted implants may be considered a viable treatment option for the rehabilitation of edentulous patients.