Clinical Outcomes with Conelog^® Screw-line Implants in the Posterior Mandible - Final 5-year Results of a Prospective Two-center Study

Background: A stable marginal bone and healthy peri-implant mucosa define the fundament for long-term stability of dental implants and both have impact on a satisfying esthetical and functional outcome. Apart from surgery, implant design and prosthetic parts have potential influence on these important outcome parameters. The CONELOG® SCREW-LINE implant by CAMLOG Biotechnologies AG offers a promising implant design with conical abutment connection and integrated platform shift. Aim: Evaluation of radiographic bone level changes from time of implant placement up to 60 months after prosthetic delivery by intraoral standardized x-rays in a prospective observational study. Secondary parameters were survival rate, performance of restorative components, nature and frequency of adverse events and the patient satisfaction. Material and Methods: Two to three implants of diameters 3.8 and 4.3 mm and lengths of 11 and 13 mm were inserted in the posterior mandible. Opposing dentition were natural teeth or fixed restorations. The implant shoulder was placed at bonelevel. Prosthetic delivery (loading) took place after 6-12 weeks in class I-III or 12-18 weeks in class IV bone. Peri-apical radiographs were taken after surgery and before and after abutment/crown placement. Routine clinical controls, photographs, and peri-apical radiographs were taken at 6, 12, 24, 36, 48 and 60 months after loading. Results: 52 implants were set in 24 patients. Mean age was 48.9 (SD ±13.8). Twenty patients received two, 4 had three neighbouring implants. Thirty-six implants in 17 patients could be followed over 60 months post loading. Seven patients (n=16 implants) dropped out during the course of the study. One patient withdrew consent, two patients died, three patients were lost to follow-up and one patient dropped out by implant failure after 16 months. Two implants got lost equivalent to a survival rate of 95.4%. Between insertion and loading mean bone loss was 0.5 mm (SD: ±0.4) and between loading and 6 months a bone gain of 0.1 mm (SD ± 0.4) was observed. A gain of 0.2 mm (SD: ±0.5) was reported after 24 months and this finding remained stable to the end of the study after 60 months: 0.2 mm (SD: ±0.6). Conclusions and clinical implications: The CONELOG® SCREW-LINE implant is safe and reliable for the partially edentulous patient in the distal mandible with a good performance regarding implant survival, esthetical outcome and bone stability over the course of the study. Parole chiave: dental implants, platform switch, mandible