Backgroud and Aim: According to the Brånemark protocol a stress-free healing period is one of the most emphasized requirements for implant integration. Therefore, implant placement traditionally used to be a two-stage procedure. Various experimental and clinical studies suggested a progressive shortening of the implant healing period and immediate loading for the edentulous mandible has become a standard approach. The purpose of the study was to compare immediately loaded and non-loaded submerged and transmucosal healed implants by changes in bone levels after 4 months. It is of special interest if transmucosal healing has an effect on peri-implant bone loss compared to submerged implants. 
Methods and Materials: 20 patients with edentulous mandibles requiring implant-supported rehabilitation will be  included in the study. Six implants (Astra Tech Implant System EV, Dentsply Sirona Implants) were placed according to the manufacturer’s instruction. Measurements of Periotest values (PTVs), radiographs, a bone- surface scan using the CEREC Omnicam as well as conventional impressions were taken immediately after the insertion of the implants. The implants in position 34 and 44 were submerged, the implants 32 and 42 were left for transmucosal healing. Within 48 hours a Friadent Gold Bar was connected to the implants 33 and 43 and the existing denture adapted accordingly. At re-entry after 4 months, a full thickness flap was elevated, exposing the margins of all implants. A second surface scan as well as conventional impressions were taken. The parameters to be evaluated were PTVs as well as peri-implant bone loss evaluated by probing and analyzing the intraoral impressions and digital scans in a CAD/CAM design software (Autodesk® Fusion 360).
Results: In a preliminary analysis 8 patients were included. A digital method for measuring the circumferent crestal bone loss in the optical scans could be developed. Starting from the cover screw of the implant, a parallel reference plane was constructed at a distance of 3 mm. Starting from this, a cylinder was drawn in the apical direction. The crestal bone resorption could thus be precisely measured. The mean Periotest value after 4 months was -6.5 for the loaded and -7.5 for the non-loaded submerged and transmucosal healed implants. By analyzing the marginal bone loss in the digital scans, we found comparable bone height changes at all implant positions although bone loss was generally higher on the buccal side. The mean crestal bone loss was -0.3 mm for the submerged and -0.2 mm for the loaded and -0.5 mm for the transgingival non-loaded implants. The differences in crestal bone loss and the changes of PTV showed no significant differences between the groups. 
Conclusion: The preliminary results revealed differences between immediately loaded implants and non-loaded submerged and transmucosal healed implants. Crestal bone resorptions were higher around loaded implants, however all implants showed stable Periotest values. Immediate loading of two interforaminary implants with Friadent Gold Bar  integration is a viable treatment option in regard to implant stability (PTV).

Comparison of immediately loaded, submerged and transmucosal healed implants: Preliminary results

[digitaldays.eao.org](https://digitaldays.eao.org/en/)