In a randomized controlled clinical trial carried out at the Ignatius teaching hospital in Breda, The Netherlands, 110 edentulous patients with severe mandibular bone loss were treated with implants of the ITI Dental Implant System using 3 different treatment strategies: a mandibular overdenture supported by either 2 implants with ball attachments, 2 implants with an interconnecting bar, or by 4 interconnected implants. In this study, results of clinical and radiographic parameters were evaluated and compared over a period of 19 months after implant placement. A total of 283 ITI Dental Implants were placed. Six implants (2%) were lost during the osseointegration period. No further implant losses occurred after that. At the 19 month evaluation mean values and standard deviations for bleeding index were 0.51 +/- 0.5 (bleeding incidence = 70%) and for plaque index they were 0.46 +/- 0.5 (plaque incidence = 45%). The mean values and standard deviations for probing depth and loss of attachment were 2.7 +/- 1.1 mm and 0.26 +/- 0.6 mm respectively. The radiographic evaluation showed a mean bone loss of 1.5 mm +/- 0.26 after 19 months for all the implants. In cases with 4 interconnected implants there was significantly more bone loss around the central 2 implants (2.1 +/- 0.31 mm) in comparison with the lateral 2 (1.4 +/- 0.25 mm). No significant correlations were found between plaque and bleeding indices and bone loss.