Abstract A randomised clinical trial was performed to investigate whether there is a need or advantage to splint two implants in the mandible retaining a hinging overden- ture. Furthermore, patient satisfaction was evaluated for different attachment systems retaining the overdenture. Thirty-six edentulous patients were randomised into three groups of equal size and treated with either magnets, ball attachments or straight bars (reference group). After 3 years of observation no implants were lost in any of the groups. Besides, no statistically significant differences were noted for the peri-implant outcome. Although the bar group presented the highest retention force, the general sat- isfaction of the patients in the three groups did not differ. The patients with bar retentions showed less prosthetic complications of the retention elements but more at the level of the denture-supporting mucosa. Finally, the clinical outcome of all groups confirms that overdenture treatment demands regular controls with limited time intervals. Key words Splinted/unsplinted implants · Mandible · Overdenture · Patient satisfaction Introduction The clinical application of the principles of osseointegra- tion opened new therapeutic approaches in oral rehabilita- tion, especially of fully edentulous patients. Such proce- dures have contributed to improvement of chewing func- tion, oral comfort and quality of life [1–3]. Routine treat- ment of edentulism with fixed full prostheses supported by osseointegrated implants appears to give acceptable long-term results in large patient populations [4–6]. Fur- thermore, the outcome of many studies with implant- retained overdentures indicated comparable levels of im- plant success in the lower jaw [7–16]. However, very few controlled studies have dealt with the comparison of splinted and unsplinted implants supporting an overden- ture [12, 15, 17]. Success of treatment with oral implants depends on the clinical outcome of the implants as well as on patient sat- isfaction and only few evaluations are available on both aspects [3, 16, 18]. A 5-year randomised clinical trial was set up to investigate the possible advantages of splinting two implants in the mandible for retention of a hinging overdenture. This paper deals with the 3-year results. Materials and methods Patient selection Thirty-six edentulous patients (19 women and 17 men) were select- ed for this study. The age ranged between 36 and 85 years (mean 63.7 years). All patients complained about their existing lower den- tures, which were satisfactory from a technical point of view. The patients were informed about the benefit of treatment with an over- denture retained by two endosseous implants. The exclusion criteria were insufficient bone volume to harbour at least two 10-mm implants, Angle class II jaw relationship, psy- chological problems for accepting a removable denture, gagging re- flexes, less than 1 year of edentulism in the mandible, absence of a maxillary complete denture and administrative or physical consid- erations that would seriously affect the surgical procedure or consti- tute a hindrance for a 5-year follow-up. Clin Oral Invest (1997) 1: 81–88 © Springer-Verlag 1997 I. E. Naert · S. Gizani · M. Vuylsteke D. van Steenberghe A randomised clinical trial on the influence of splinted and unsplinted oral implants in mandibular overdenture therapy A 3-year report ORIGINAL ARTICLE I. E. Naert () · S. Gizani Department of Prosthetic Dentistry, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University Leuven, Kapucijnenvoer 7, B-3000 Leuven, Belgium Tel.: +32 16332467; Fax: +32 16332435; e-mail: ignace.naert@med.kuleuven.ac.be M. Vuylsteke Department of Statistics, Computing Centre, Catholic University Leuven, de Croylaan 52A, B-3001 Heverlee, Belgium D. van Steenberghe Department of Periodontology, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University Leuven, Kapucijnenvoer 7, B-3000 Leuven, Belgium