Research Article Leakage of Microbial Endotoxin through the Implant-Abutment Interface in Oral Implants: An In Vitro Study Rhoodie Garrana, 1 Govindrau Mohangi, 2 Paulo Malo, 3 and Miguel Nobre 4,5 1 Department of Oral Medicine & Periodontology, School of Oral Health Sciences, Faculty of Health Science, University of the Witwatersrand, 7 York Road, Parktown 2193, Johannesburg, South Africa 2 Clinical Unit, Department of Oral Medicine & Periodontology, School of Oral Health Sciences, Faculty of Health Science, University of the Witwatersrand, Johannesburg, South Africa 3 Malo Clinic Health and Wellness, Av. dos Combatentes 43A, 1600-042 Lisbon, Portugal 4 Research and Development Department, Malo Clinics, Av. dos Combatentes 43A, 1600-042 Lisbon, Portugal 5 Oral Hygiene Department, Malo Clinics, Av. dos Combatentes 43A, 1600-042 Lisbon, Portugal Correspondence should be addressed to Rhoodie Garrana; rmgarrana@gmail.com Received 19 September 2016; Revised 24 November 2016; Accepted 12 December 2016 Academic Editor: Elizabeta Gjorgievska Copyright © 2016 Rhoodie Garrana et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background. Endotoxin initiates osteoclastic activity resulting in bone loss. Endotoxin leakage through implant abutment connections negatively infuences peri-implant bone levels. Objectives. (i) To determine if endotoxin can traverse diferent implant- abutment connection (IAC) designs; (ii) to quantify the amount of endotoxins traversing the IAC; (iii) to compare the in vitro comportments of diferent IACs. Materials and Methods. Twenty-seven IACs were inoculated with E. coli endotoxin. Six of the twenty-seven IACs were external connections from one system (Southern Implants) and the remaining twenty-one IACs were made up of seven internal IAC types from four diferent implant companies (Straumann, Ankylos, and Neodent, Southern Implants). Results. Of the 27 IACs tested, all 6 external IACs leaked measurable amounts of endotoxin. Of the remaining 21 internal IACs, 9 IACs did not show measurable leakage whilst the remaining 12 IACs leaked varying amounts. Te mean log endotoxin level was signifcantly higher for the external compared to internal types ( = 0.015). Conclusion. Within the parameters of this study, we can conclude that endotoxin leakage is dependent on the design of the IAC. Straumann Synocta, Straumann Cross-ft, and Ankylos displayed the best performances of all IACs tested with undetectable leakage afer 7 days. Each of these IACs incorporated a morse- like component in their design. Speculation still exists over the impact of IAC endotoxin leakage on peri-implant tissues in vivo; hence, further investigations are required to further explore this. 1. Introduction In conventional two-piece implant systems, the abutment is connected to the implant mechanically via a screw. Tis creates an interface through which leakage may occur. In 1977, the frst dental implant was designed by Br˚ anemark et al. and was manufactured for human implantation and consisted of a screw retained slip-ft butt-joint external hexagon connection [1]. Te external hex connection was the frst connection design and was used primarily as a carrier of the device into the mouth [1]. Te external implant-abutment connection however does present with several mechanical and biological complications such as screw loosening, rotational misft at the implant-abutment interface, and microbial penetration [2]. Implant-abutment connections have evolved greatly in an attempt to minimize these complications. Leakage however is not isolated to external connections and may occur in internal connection designs as well; however, the quantity of leakage is unknown in both design types. In 1986, one of the frst internal implant-abutment connections was developed by Niznick [3]. Tis connection was designed with a 1.7 mm deep internal hexagon connection below a 0.5 mm wide 45- degree taper which proved to have superior force distribution properties when compared to the original external hexagon Hindawi Publishing Corporation BioMed Research International Volume 2016, Article ID 9219071, 6 pages http://dx.doi.org/10.1155/2016/9219071