Title Implant Survival and Complications Rates Are Similar Between Internal and External Connection Implants
Clinical Question In patients requiring implant-supported restorations, does the use of an internal connection implant system result in fewer mechanical and/or biological complications than an external connection implant system?
Clinical Bottom Line The choice of implant connection does not appear to influence implant survival. However, the use of an internally connected implant restoration can be expected to reduce the number of mechanical complications (screw loosening and screw fracture) compared to an externally connected system. Conversely, low-level evidence suggests the use of internal implant connections for FDPs may create a greater risk of biologic complications (greater than 2 mm coronal bone loss).
Best Evidence  
PubMed ID Author / Year Patient Group Study type
(level of evidence)
30306682Pjetursson/201860 studies: 5,988 implant abutments total (59% internal connection, 41% external connection)Systematic review of non-randomized trials
Key resultsThis robust systematic review grouped implant abutments into two main groups: single crowns (SCs) and FDPs, and each group contained internal (IC) and external connection (EC) implants. The subgroups also looked at metal vs. ceramic abutments. For all groups, there were no significant differences in implant survival rates between EC and IC. Similar complication rates were reported for both IC and EC implants. Technical complications were slightly more frequent with EC implants, while biologic complications were more frequently seen with IC implants without any statistically significant differences. Most common technical complications were abutment screw fracture/loosening (significantly higher for externally connected crowns and FDPs). Most common biologic complications were soft tissue inflammation/recession, but bone loss greater than 2 mm was seen significantly more often with internally connected FDPs than with externally connected FDPs.
29221955Lemos/201811 studies: 1,089 implants (461 external connection, and 628 internal connection)Meta-Analysis
Key resultsAll studies included compared the two types of implant-abutment connection. Failure of implants was reported to be 2.39% for internal connection implant systems, and 1.52% for external connection, with no statistically significant differences. Lower values of marginal bone loss were reported for restorations with internal connection implant systems than external connection, unlike the Pjetursson review. Although complications rates were higher for external connection implant systems, statistical analysis shows no significant differences. The included studies had short follow-up periods (<5 years); however, technical complications are usually seen after long periods of function on the restoration.
Evidence Search Dental implant[All Fields] AND Internal[All Fields] AND External [All Fields] AND Complication[All Fields]
Comments on
The Evidence
Validity: The two articles are systemic reviews, with one (Lemos 2018) also performing a meta-analysis. In both articles, the search included terms relevant to the focused question, and both electronic and manual searches were completed involving journals related to the topic. In the Pjetursson article, the inclusion criteria focused less on the type of studies and more on the reported outcomes. Although only human studies were included, the follow-up minimum was 3 years, and no RCT studies were included. Based on a new quality assessment scale (examining reported cohort and drop out rates), more than half (62%) of the studies included were judged to have high methodological quality and low risk of selection bias (in spite of inherent selection bias with cohort studies). Studies included in the Lemos article were generally considered as higher quality evidence due to their inclusion criteria (only RCTs and prospective studies with a good number of samples were included). Their risk of bias assessment also judged the included studies as moderate to high quality. However, the overall body of evidence was considered low to moderate quality due to study limitations, inconsistencies, and asymmetry of outcomes reported. As for limitations, studies included in both reviews reported outcomes on implant therapy that are either present or absent, such as implant survival/failure and biologic and technical complications. A more detailed measurement of those outcomes could provide further insight into these observations. Furthermore, the implant position in the oral cavity was not examined in the included studies, and authors of both reviews acknowledged this as a limitation of the reported results. Perspective: Technical complications can be related to the implant-abutment connection selected. Most of the studies report slightly higher rates of technical complications with external connection systems. However, very few studies included in these reviews have a follow-up period of more than 5 years, and previous reviews report that most technical complications arise with longer periods of observation. Implant survival rates compared in these reviews can be affected by other factors not included in the analysis of the results: factors such as implant dimensions, bone type, the position of implants, and retention system.
Applicability While the type of implant system connection (external v. internal) does not appear to influence implant survival, the significantly higher incidence of screw fracture and screw loosening seen with external connections may be of concern for high load conditions.
Specialty (Oral Surgery) (Periodontics) (Prosthodontics) (Restorative Dentistry)
Keywords Implant abutment, external connection, internal connection, complications
ID# 3343
Date of submission 12/10/2018
E-mail alawadi@uthscsa.edu
Author Ahmad Alawadi, DDS
Co-author(s) e-mail
Faculty mentor Stephan Haney, DDS
Faculty mentor e-mail haneys2@uthscsa.edu
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
Comments and Evidence-Based Updates on the CAT
None available