The randomized shortened dental arch study: tooth loss over five years

The study was designed to provide clinical outcome data for two treatments of the shortened dental arch (SDA).

In a multicenter randomized controlled clinical trial, patients with complete molar loss in one jaw were provided with either a partial removable dental prosthesis (PRDP) retained with precision attachments or treated according to the SDA concept preserving or restoring a premolar occlusion. No implants were placed. The primary outcome was tooth loss.

Of 152 treated patients, 132 patients reached the 5-year examination. Over 5 years, 38 patients experienced tooth loss. For the primary outcome tooth loss, the Kaplan-Meier survival rates at 5 years were 0.74 (95% CI 0.64, 0.84) in the PRDP group and 0.74 (95% CI 0.63, 0.85) in the SDA group. For tooth loss in the study jaw, the survival rates at 5 years were 0.88 (95% CI 0.80, 0.95) in the PRDP group and 0.84 (95% CI 0.74, 0.93) in the SDA group. The differences were not significant. No Cox regression models of appropriate fit explaining tooth loss on the patient level could be found.

The overall treatment goals of a sustainable oral rehabilitation and the avoidance of further tooth loss over longer periods were not reliably achievable. The influence of the type of prosthetic treatment on tooth loss might have been overestimated.

Regarding our results, the patient's view will gain even more importance in the clinical decision between removable and fixed restorations in SDAs.