Title Increased Number of Supporting Implants for Full-Arch Fixed Dental Prosthesis Is Not Associated with Higher Survival Rates
Clinical Question For a patient receiving a full-arch implant-supported fixed dental prosthesis (hybrid prosthesis), is an increased number of supporting implants associated with higher survival rates?
Clinical Bottom Line The use of four to six implants to support a full-arch fixed dental prosthesis is well-supported by current literature. There was not a statistically significant difference in implant or prosthesis survival rates when comparing the use of less than five supporting implants to five or more supporting implants. The use of three supporting implants is not as well-supported by current literature, with lower implant and prosthesis survival rates when compared to four or more supporting implants. However, this configuration has not been studied as extensively and the authors of the included systematic reviews suggest the need for further studies and longer follow-up periods.
Best Evidence  
PubMed ID Author / Year Patient Group Study type
(level of evidence)
30328199Polido/201893 studies/9 RCTs, 42 prospective, 42 retrospectiveSystematic review
Key resultsThis review demonstrated similar outcomes for implant and prosthesis survival rates when comparing the use of <5 supporting implants (per arch) to ≥5 supporting implants (per arch) in both the maxilla and mandible. There were no statistically significant differences between the groups (p > 0.05), with a follow-up period ranging from 1 to 15 years. The authors acknowledged that a “one-fits-all” approach cannot be identified, and each patient’s treatment plan should be tailored to their individual needs and circumstances. When evaluating the risks and benefits of choosing a certain number of implants, one should take into consideration a number of variables unique to each patient (prosthesis material and design, esthetic considerations, AP spread, restorative space available, edentulous ridge [size, presence of defects, bone type/quality], etc.).
30024995Lima/201821 studies/1,245 patients, 1,245 mandibular full-arch fixed dental prosthesesSystematic review
Key resultsThe authors grouped the patients according to number of implants placed: Group 1 – three implants, Group 2- four implants, Group 3 – five implants. Group 3 had the lowest implant survival rate (74%), while Groups 1 and 2 had a 90% and 95% implant survival rate, respectively. Group 2 had a statistically significant difference in first-year bone loss (median: 1.31 mm, p<0.001) when compared to Groups 1 and 3 (median: 0.73 and 0.70 mm, respectively). All three groups had satisfactory implant and prosthesis survival rates, as well as first-year bone loss. However, Group 1 had lower prosthesis survival rates than Groups 2 and 3. The authors suggested longer follow-up of patients treated with these prostheses.
23062144Heydecke/20129 studies/6 studies focused on full-arch fixed dental prosthesesSystematic review of non-randomized trials
Key resultsThe survival rate for maxillary full-arch fixed dental prostheses (supported by 4-6 implants) was 97.5% after 5 years and 95.0% after 10 years. The survival rate for mandibular full-arch fixed dental prostheses (supported by 4-6 implants) was 97.9% after 5 years and 95.9% after 10 years. The authors concluded that the use of 4-6 supporting implants for full-arch fixed dental prostheses was a predictable and well-supported treatment modality with high survival rates at 5 and 10 years. The ability to achieve comparable survival rates when using 3 supporting implants was unclear.
Evidence Search Pubmed.gov search: implant-supported fixed dental prosthesis OR hybrid prosthesis AND number of dental implants Pubmed.gov search: implant configurations AND full-arch implant-supported fixed dental prosthesis
Comments on
The Evidence		 Validity: The cited systematic reviews clearly stated their methods, with detailed descriptions for inclusion and exclusion criteria. The majority of the articles included by Polido/2018 exhibited low to moderate risk of bias. This review included 9 RCTs, only 1 of which answered the PICO directly, which is why the other prospective and retrospective studies were included. Statistically significant heterogeneity was found among the included studies in all four meta-analyses by Polido et al. The majority of the articles included in the Lima/2018 review were fair to high quality; the included RCT exhibited a moderate risk of bias. Perspective: A high level of evidence was located to answer this clinical question; however, research is lacking for the use of three implants to support a full-arch fixed dental prosthesis. As all of the authors in the systematic reviews concluded, more studies on the use of three implants is needed to support the efficacy of this treatment modality.
Applicability Full-arch fixed dental prostheses are becoming increasingly popular as a treatment modality for edentulous patients. Predictable, long-term success can be achieved using four to six supporting implants as long as patient-specific factors have been taken into consideration. Further research with longer follow-up periods is needed for the use of three supporting implants.
Specialty (Prosthodontics) (Restorative Dentistry)
Keywords Dental Implants, Hybrid Prosthesis, Full-Arch Fixed Dental Prosthesis
ID# 3437
Date of submission 12/15/2020
E-mail gossc@livemail.uthscsa.edu
Author Casey D. Goss, DMD
Co-author(s) Daniel Lee, DDS
Co-author(s) e-mail leed10@livemail.uthscsa.edu
Faculty mentor Matthew R. Checketts, DDS
Faculty mentor e-mail matthew.r.checketts.mil@mail.mil
   
Basic Science Rationale
(Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?)
None available
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Comments and Evidence-Based Updates on the CAT
(FOR PRACTICING DENTISTS', FACULTY, RESIDENTS and/or STUDENTS COMMENTS ON PUBLISHED CATs)
None available