Rehabilitation of edentulous mandibles by means of osseointegrated implants: a 5-year follow-up study on one or two-stage surgery, number of implants, implant surfaces, and age at surgery.

BACKGROUND

In three former reports, the present team has presented the 1-year outcome of four different treatment procedures handling the edentulous mandible; that is, two-stage and one-stage surgery with turned Brånemark System® (Nobel Biocare AB, Gothenburg, Sweden) implants (Group 1 and 2) and one-stage surgery using either 5 or 4 TiUnite™ (Nobel Biocare AB, Gothenburg, Sweden) implants (Group 3 and 4).

PURPOSE

The aim of the present investigation was to follow up these patients for a period of 5 years with regard to implant/prosthesis cumulative survival rates, marginal bone loss calculations, clinical complications, and results related to age at surgery.

MATERIALS AND METHODS

A total of 385 patients, provided with 1,838 implants, were originally included in the four patient groups. All patients received fixed prostheses. The overall majority of patients had each five implants placed. Radiographs were obtained at prosthesis delivery, at the 1 and 5-year follow-up.

RESULTS

A total of 1,230 implants in 259 patients (67%) were possible to follow up for 5 years. Implant Cumulative Survival Rates (CSR) in 5 years for Groups 1-4 were 99.7, 97.0, 98.5, and 98.6%. The corresponding prosthesis treatment CSR was 100, 99.3, 98.5, and 98.6%, respectively. Significantly, more patients (p< .05) lost turned implants after one-stage surgery (Group 2). Frequency distributions of implants revealed that >1.2 mm bone loss was observed around 75 implants (6.4%). The moderately rough central (midline) implant showed more bone loss than other placed implants (Group 3; p< .05). The youngest half of included patients at surgery (Youngest(50%) ; n=193) presented significantly higher mortality than older patients as well as compared to normal population (p< .05). Patients in the Younger(50%) group showed also an association to patients with complete loss of all implants and patients with most implants with obvious bone loss after 5 years.

CONCLUSIONS

All four treatment procedures served well during the 5 years of follow-up and only eight patients (2.1%) were complete failures or showed obvious bone loss (>1.8 mm) at several implants (>2 implants), mostly observed in younger patients. The few complications in relation to implant failure and/or obvious bone loss could be associated to both local impact factors (surface, implant site, surgical protocol) as well as to host response factors (systemic health).