Internal- vs External-Connection Single Implants: A Retrospective Study in an Italian Population Treated by Certified Prosthodontists

Abstract

The design of an implant connection that allows prosthetic suprastructures to be attached to implants has long been debated in the dental literature. The goal of this retrospective study was to evaluate the 5-year clinical results for a large number of single implants restored by certified prosthodontists in an attempt to establish whether different clinical outcomes could be detected for external-or internalconnection implants. Materials and Methods: All single implants with internal or external connections inserted in 27 private dental practices from January 1, 2003 to December 31, 2007 were evaluated. An initial statistical analysis was performed to describe the sample population at baseline and then to compare the two types of implant-abutment connection configurations and their clinical outcomes. All data were statistically analyzed with STATA12 (StataCorp). Results: Twenty-eight of the 85 active members of the Italian Academy of Prosthetic Dentistry (AIOP) participated in this study. The sample included 1,159 patients and 2,010 implants. Of the implants, 75 were dropped because there was no information about follow-up. Of the remaining implants, 1,431 (74.0%) were followed for at least 5 years, and 332 implants (17.2%) were followed for more than 8 years. Nearly 99% (98.9%) of the implants survived. The difference between the survival frequencies of the two types of implant-abutment connection configurations was not significant for each negative event (log-rank test, P > .05). There was no difference between the two types of implants regarding restoration fracture, implant screw loosening, and peri-implant disease. Conclusion: Within the limitations of this study, it can be suggested that there is no difference in clinical outcomes of single restorations joined to internal-or external-connection implants.

Mechanism of and factors associated with the loosening of the implant abutment screw: A review

“…There are also studies stating that the difference in connection types does not have a significant influence on screw loosening. Vigolo et al compared the two connection types by a retrospective study. In a follow‐up period of at least 5 years involving 2010 implants in 1159 patients, no significant difference was found in the incidence of screw loosening between two connections, which was similar to the result of Chae et al However, many other factors may also affect the results in clinical practice.…”

Loosening of the fixing screw in single implant crowns: predisposing factors, prevention and treatment options

“…The problem is often encountered in external hexagon implants during the first 2 years from the placement of the prosthetic restoration, while specific reference is made regarding the screw loosening in single external hexagon implants than in similar implants with internal connection . Nevertheless, it is worth mentioning that in other in vitro and in vivo studies, it was reported that internal connection showed no advantage regarding screw loosening compared to external connection. It should be mentioned, however, that, although the clinical trials included a great number of patients and implants, the treating clinicians were certified prosthodontists and the outcomes should be interpreted with caution as they may not represent the clinical reality of a wide number of practitioners.…”

“…3,7,24,31,32 The problem is often encountered in external hexagon implants during the first 2 years from the placement of the prosthetic restoration, 22 while specific reference is made regarding the screw loosening in single external hexagon implants than in similar implants with internal connection. 11 Nevertheless, it is worth mentioning that in other in vitro 33,34 and in vivo studies, 35,36 it was reported that internal connection showed no advantage regarding screw loosening compared On the other hand, some studies 25,37,38 support the superiority of the conical connection over the internal and the external hexagon, as the micro-motions of the prosthetic abutment, the expanding of the micro-gaps under pressure and the industrial stability are concerned. 39 The conical connection (Figure 21) is the type of internal connection that minimizes the gap between implant and prosthetic abutment with In the majority of clinical studies, technical problems occurred more frequently in screw-retained restorations (57%) compared to cement-retained (22.8%), with most common the loosening of the fixing screw of the abutment.…”

Comparison of external and internal implant-abutment connections for implant supported prostheses. A systematic review and meta-analysis

“…After reviewing the titles and abstracts of the manuscripts and applying the inclusion/exclusion criteria, 23 studies were eligible for further analysis. After reading these studies, 12 were excluded as they were retrospective studies [24][25][26][27][28][29][30][31][32] or had their data included in other articles with longer follow-ups [33][34][35] Altogether, 11 studies were selected for this systematic review [2,4,34,[36][37][38][39][40][41][42][43][44] Fig. 1 depicts a flow diagram detailing the search strategy.…”