Survival rates of short-span implant-supported cantilever fixed dental prostheses

Publications were sought using Medline, and searches were made by hand of the journals Clinical Oral Implants Research, International Journal of Periodontics and Restorative Dentistry, Journal of Periodontology, Journal of Clinical Periodontology and the International Journal of Oral and Maxillofacial Implants, along with reference lists of identified articles.

Titles and abstracts were initially screened by two independent reviewers to identify prospective or retrospective longitudinal cohort studies or controlled studies reporting on implant-supported cantilever fixed dental prostheses (ICFDP) with a mean followup period of at least 5 years. A clinical examination had to be performed at the end of the followup. For multiple publications reporting on the same population, only the most recent report was included.

Data for the meta-analysis were extracted by two independent reviewers. Information regarding survival and complication rates of both implants and ICFDP were extracted. Implant survival was considered if the implant was present at the followup examination; ICFDP survival was considered if the prosthesis was present at the followup visit without any modifications. Peri-implantitis and soft tissue complications were included in the category of biological complications. As for technical complications, all the events affecting the implant and/ or the meso- and/ or the suprastructures' integrity were considered. Among them, the following categories were defined: implant fractures, veneer fractures, framework fractures, abutment or screw fractures, loss of retention and screw loosening.

The five studies included in the meta-analysis yielded an estimated 5- and 10-year ICFDP cumulative survival rate of 94.3% [95% confidence interval (CI), 84.1-98%] and 88.9% (95% CI, 70.8- 96.1%), respectively. Five-year estimates for peri-implantitis were 5.4% (95% CI, 2.0-14.2%) and 9.4% (95% CI, 3.3-25.4%) at implant and prosthesis levels, respectively. Veneer fracture (5-year estimate; 10.3%; 95% CI, 3.9-26.6%) and screw loosening (5-year estimate, 8.2%; 95% CI, 3.9-17.0%) represented the most common complications, followed by loss of retention (5-year estimate, 5.7%; 95% CI,1.9-16.5%) and abutment/ screw fracture (5-year estimate, 2.1%; 95%CI, 0.9-5.1%). Implant fracture was rare (5-year estimate, 1.3%; 95% CI, 0.2-8.3%); no framework fracture was reported. Radiographic bone level changes did not yield statistically significant differences either at the prosthesis or at the implant levels when comparing ICFDP with short-span implant-supported end-abutment fixed dental prostheses.

ICFDP represent a predictable and reliable treatment for the replacement of posterior missing teeth in partially edentulous patients. The most frequent technical complications included veneer fractures, followed by screw loosening and loss of retention. No detrimental effects on bone levels were observed around implants in the proximity of cantilever extensions. To date, however, evidence is still sparse on the effects of various prosthetic designs (eg, distal or mesial cantilever extension), number of implants supporting ICFDP and occlusal concepts on the incidence of complications in ICFDP.