External Connection versus Internal Connection in Dental Implantology. A Mechanical in vitro Study

Abstract

(1) Background: In today's dentistry, implantology has become a therapeutic resource of choice in certain clinical situations. The design of implants has evolved in several aspects since their inception. Dental implants were initially designed with an external hex connection, although due to force transmission and security in the adjustment of the prosthesis, later implants featured an internal hex connection. This study aims to analyse the mechanical properties of two types of implants (an internal connection and an external connection) from the same manufacturer and their different prosthetic components (union screw between implant and prosthetic abutment, and the abutment itself) when subjected to different types of load. (2) Materials and methods: Intraosseous dental implants of similar shape, design and size, although different in type of connection (external vs. internal), were studied. The specifications of the UNI EN ISO 14801 test standard were used, with all determinations being carried out three times. Finally, the dimensional characterisation of the samples analysed after the dynamic load study was carried out, and the values of both study groups were compared by means of the non-parametric Mann–Whitney U test to find statistically significant differences (p < 0.05). (3) Results: For the static characterisation test, we found between 610.9 N and 986.1 N for the external connection and between 1263.6 N and 1324 N for the internal connection (p = 0.011). All of the dynamic load tests were positive and there was no failure in any of the components studied. (4) Conclusions: After the analysis of the samples studied in vitro, satisfactory results were obtained, demonstrating that both connections can support considerable mechanical loads according to international standards (UNI EN ISO 14801).