38 Clinical evidence and Science In a randomized split-mouth design in 16 patients immediately loaded CONELOG® implants were directly compared to delayed loaded implants with a healing time of eight weeks (Erhan Cömlekoglu et al. 2018) (4). In the test group of the immediately loaded implants the definitive abutment was placed from the beginning and was digitally restored while in the control group repeated disconnections and reconnections had to be done. At the 12 months control the test group exhibited significantly reduced vertical bone loss. The soft tissue health and aesthetics as well as the complications rate was similar in both groups. The one abutment-one time concept The concept of placing the definitive abutment from the beginning without detaching it again, called «one abutment-one time protocol», as applied in the study described above, is believed to preserve the peri-implant soft and hard tissue in contrast to multiple disturbance of the peri-implant region by exchanging healing caps, impression posts, and abutments. This was shown in a pre-clinical dog study using CONELOG® implants with two exchanges of abutments (Becker et al. 2012) (5). The abutments were disconnected and reconnected four and six weeks after implant insertion or left undisturbed. Histological evaluation at eight weeks demonstrated that abutment exchanges resulted in a disruption of the mucosal seal as well as in an increased apical extension of the junctional epithelium and bone resorption compared to undisturbed healing. The authors concluded that repeated abutment manipulation may increase soft and hard-tissue changes in implants with Platform-Switching design. In the clinic, a review by Atieh et al. (2017) found significant differences for marginal bone level changes in favor of the «one abutment-one time protocol» but on the same time questioned the clinical significance (6). A deeper insight in the following clinical studies investigating the concept with Camlog products may give a clearer picture. Similar to the study of Erhan Cömlekoglu et al. as described above a study team from the University of Complutense, Madrid, investigated in a randomized clinical study the effect of placing the definitive abutment right at the time of implant placement compared to a healing time of 6–12 weeks (Molina et al. 2017, Fierravanti et al. 2018) (7, 8). The outcome of the soft and hard tissues were assessed in detail by measuring the marginal changes of the gingiva, the papillae, and the bone level changes also in relationship to the adjacent teeth. The patients received CONELOG® implants with integrated Platform-Switching in the posterior maxilla or mandible. Molina et al. (2017) reported the one-year follow-up data while Fierravanti et al. (2018) presented the three years follow-up at a congress. The group with connection and disconnection of the healing abutment showed a statistically significant increased bone loss compared to the group with definitive abutments placed at surgery. The difference was established during the healing phase up to 6 months post-loading. Afterwards both concepts showed stable bone level changes and even a slight bone gain from the one year to three years follow-up. The soft tissue parameters, however, demonstrated no statistical significances between both groups. From a clinical side, the one abutment-one time concept applied with CONELOG® implants seems to preserve the bone better during the initial remodeling phase. PROSTHETIC RESTORATIONS: SCIENTIFICALLY BASED TREATMENT OPTIONS
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