Clinical and Radiographic Outcomes of Implant-supported Prostheses With Cantilever Extensions After 10 Years of Function

The successful use of osseointegrated dental implants in replacing missing teeth has been adequately documented, with multiple studies reporting long-term success exceeding 10 years of function. However, there is still insufficient evidence in cases where availability of adequate bone precludes ideal placement of implants. Examples of cases like these include the posterior maxilla when pneumatization of the maxillary sinus does not allow for placement of implants, or areas of thin bone that would require extensive guided bone regeneration (GBR) techniques and increase patient morbidity. In such cases the use of fixed dental prostheses (FDPC's) with cantilever extension has been suggested in lieu of sinus lift techniques or GBR procedures. However, few studies have actually addressed the long-term success of such FDPC's, both from a surgical and a prosthetic standpoint, especially in posterior areas of the mandible and maxilla where loading forces are expected to be higher.

Two studies addressed this issue in the early 2000's with successful outcomes reported for an observation period of 5 years. Others reported similar outcomes after a mean observation period of 5.6 years. The 5th Consensus Conference of the European Association of Osseointegration (EAO) suggested that such treatment can be recommended to patients, albeit with little available evidence and limited follow-up of cases. Recent studies have delved further into this issue, offering longer follow-up data of more than 10 years of function. They included both 2 unit FDP's anchored on one implant and 3 unit FDP's anchored on two implants with cantilever extensions. They concluded that this treatment modality is a reliable option with long-term stability and few complications, mainly prosthetic.

The aim of this retrospective study is to offer further data on the long-term success and complications when at least two dental implants are used to support a FDPC in the posterior areas of both jaws, after at least 10 years of function.

The inclusion criteria were as follows:

• Age 18 years and over
• Systemic health or controlled medical conditions
• Periodontal health, either no periodontal disease, or previously treated periodontal disease and under a supportive periodontal maintenance (SPT) program
• Smokers were included but encouraged to enter a smoking cessation program
• Patients with bruxism or parafunctional habits were included.

The exclusion criteria were as follows:

• Uncontrolled medical conditions
• Active uncontrolled periodontal disease
• Inability to present for the reevaluation appointment
• Immediate implant placement
• Cantilever units that were part of full-arch restorations
• Cantilever units that were connected to a single implant
• Non-existent opposing dentition