Study procedures
tooth
This multicenter RCT in a university hospital and three dental practices was approved by the Ethics Committee of the Greifswald University (BB 058/13A). All participants gave their written informed consent prior to inclusion in the study. Participants were patients with an RPD in one or both jaws with comparably unfavorable tooth distributions, i.e., one quadrant was edentulous (class 0), or one/both quadrants had either only anterior teeth (class 1), one (class 2), or at most two posterior teeth (class 3) and no canine (Fig. Classification on quadrant level per study jaw and clinical examples including placed strategic mini-implantsMini-implants for the additional support of the double crown-retained removable partial denture in the maxilla remained initially unloaded in group B. After 4 months the housings were picked-up, and the palatal base was reducedThe RPD was hollowed out over the ball abutments. Thereafter, the participants were allocated to the immediate loading group A or the delayed loading group B according to the 1:1 randomization ratio stratified by jaw and center. A sealed opaque envelope with the randomization detail was usually opened by the treatment coordinator. The surgeon was informed per telephone about the group allocation after implant placement. According to previous good experiences [