The Conometric Concept: A Two-Year Follow-Up of Fixed Partial CEREC Restorations Supported By Cone-In-Cone Abutments

To evaluate the performance of definitive, implant-supported, lithium disilicate fixed dental prostheses (LS₂ FDPs) manufactured with a computer-assisted design/computer-assisted manufacturing (CAD/CAM) system. All patients received two-unit restorations placed in posterior regions, supported by osseointegrated implants with cone-in-cone connection abutments.

Two implants (Ankylos) were placed into healed sites or fresh extraction sockets in the maxillary/mandibular posterior regions of partially edentulous patients. Definitive digital impressions were made 3 months after surgery. Twenty-four patients received fixed  monolithic LS₂ restorations manufactured with the CEREC system. All restorations were connected to the implants using cone-in-cone connection abutments. Peri-implant pocket depths were recorded for 2 years at each follow-up visit. Esthetic, functional, and biologic United States Public Health Services (USPHS) parameters modified by the FDI World Dental Federation study design were assessed yearly until the last follow-up appointment. The opposing dentitions were identified by type of restoration and supporting structures at the time of placement of the definitive restorations and at the 2-year follow-up visits.

One patient (4.16%) moved to an unknown location during the study. A total of 23 FDPs (95.8%) supported by 46 implants reached the 2-year follow-up. None of the prostheses failed, or became loose or detached. No significant difference involving probing levels between the experimental times were found.

The results of this research indicated that the abutment-prostheses connection using a cone-in-cone approach was successful within the 2-year period of this study. None of the studied monolithic LS₂ glass-ceramic prostheses milled using the CEREC CAD/CAM system fractured or became detached.