Purpose: To evaluate the 2-year performance of definitive implant- or tooth-supported three-unit fixed dental prostheses made of zirconia-reinforced lithium silicate placed to restore premolars and molars in clinical cases of partial edentulism.
Materials and methods: All patients received a three-unit fixed restoration made of monolithic, hot-pressed, zirconia-reinforced lithium silicate glass-ceramic. The restoration was cemented to two natural teeth or attached to two 3.5- or 4.5-mm-diameter square threaded, grit-blasted, acid-etched integrated implants with a Morse taper connection. Peri-implant pocket depth and bone and soft tissue remodeling were recorded for 2 years at each follow-up visit. Esthetic, functional, and biologic United States Public Health Services (USPHS) parameters modified by the World Dental Federation study design were assessed yearly until the final follow-up appointment. At the time of placement of the definitive restorations and at the 2-year follow-up visit, the opposing dentitions were identified by type of restoration and supporting structures.
Results: A total of 100 patients were consecutively enrolled in the period between June 2016 and July 2017, and 50 patients each received an implant-supported restoration (Group A) or a tooth-supported restoration (Group B). One (2%) of the 50 implant-supported prostheses fractured after 21 months of function. None of the other prostheses failed or became loose or detached. No significant differences involving probing levels or bone and soft tissue remodeling were found between the follow-up times. No cases of inflammation or infection of the mucosal cuff around the neck of the implants were recorded. The most common issue occurred immediately after placement of the prosthesis, when 3 patients (6%) from Group A and 4 patients (8%) from Group B asked for a modification of tooth shade.
Conclusion: Implant-supported or tooth-supported three-unit fixed dental prostheses made of zirconia-reinforced lithium silicate can be used to successfully restore cases of posterior partial edentulism. The 2-year results of this report will be studied more in depth in ongoing long-term research.