Single Soft Tissue Support versus Dual Tooth-Tissue Support for Clasp-Less Mesial Implant Retained Mandibular Class I Rpd: Cross-Over Clinical Study

Objective: To evaluate the single soft tissue support versus dual tooth-tissue support for mesial implant retained RPD. Materials and Methods: This clinical cross-over study included 10 partially edentulous patients with the only remaining mandibular six anterior teeth. Every patient received two mandibular implants at the 1^st premolar region. Two mandibular implants' retained partial overdentures were constructed with two different support concepts, two different designs, opposing a maxillary single denture. One of the dentures was done with a design based mainly on soft tissue support but the other denture was done with a dual tooth-tissue support design. The effects of each RPD design were studied after 1, and 5 years. The following clinical parameters were evaluated: the plaque index (PI), the bleeding index (BI), and the probing depth (PD). The peri-implant bone level changes, and alveolar bone level changes of the canine and residual ridge bone level were assessed on digital radiographs using the Corel-Draw program. The SPSS program was used for statistical analysis. Results: After 1 and 5 years of follow-up for each supporting concept of RPD, no implant failures were noted. No significant differences in soft tissue clinical parameters BI, PI, and PIP were found between the 2 designs with regard to the canine and implant, or peri-implant bone resorption. On the other hand, there was a significant difference after 1 year regarding alveolar bone loss of the canine (P=.002) and residual ridge bone loss (P=.0001) and after 5 years for the canine alveolar bone where (P= .015).  Regarding residual ridge bone loss, there was a distal descending pattern of bone resorption in the dual support design. The bone loss was increased with the dual support design (P=.0001). Conclusions: within the limits of this study, single soft tissue support for mesial implant retained removable partial overdenture was recommended versus dual tooth support. Single soft tissue support preserves the remaining structures.