title: Comparison of three in vitro implant leakage testing methods.
abstract: OBJECTIVE
  To assess the accuracy and sensitivity in detecting implants leakage with a gas-enhanced permeation test (GEPT) and to compare with a molecular- and a bacterial-based leakage tests.
  
  
  METHODS
  Three implants systems were tested (n = 20 per group): Nobel Biocare (NB), Astra Tech (AT) and Biomet 3i (B3i). Implants were mounted in PVC disks and were first tested for gas pressure change and infiltrated saline volume over 40 min. The same implants were then subjected to a molecular leakage evaluation using fluorescent Dextran for 28 days. After cleaning and sterilization, bacterial permeation (E. faecalis) was evaluated by selective media turbidity for another 28 days. Slopes in the pressure change and the perfused saline rate were used as a measure of leakage in the GEPT model and the times of positive events, that is, color change, after molecular and bacterial tests were recorded. Data were analyzed using Kolmogorov-Smirnov/Shapiro-Wilk, Kruskal-Wallis H and Spearman's Rho tests (P < 0.05).
  
  
  RESULTS
  The gas and saline (ml) leakage values accounted for 0.85 ± 0.71 and 0.56 ± 0.50 ml (AT), 0.23 ± 0.030 and 0.12 ± 0.20 ml (NB) and 0.01 ± 0.01 and 0 ± 0 ml (B3i), respectively, and were significantly different from each other (P < 0.001). Slope in the pressure change over time showed a significant positive correlation with the collected saline solution (r = 0.91; P < 0.001). Molecular and bacterial leakage was positive at the same implants, which also showed increased leakage values in the GEPT setup. The development of positive events in the timeline of the bacterial leakage evaluation corresponded well to the GEPT leakage model.
  
  
  CONCLUSIONS
  The GEPT proved to be a reliable method to quantify leakage. The B3i showed the best sealing among the tested systems.
authors: Clinic of Preventive Dentistry, Periodontology and Cariology, Center for Dental Medicine, University of Zurich, Zurich, Switzerland.
authors: Anas
authors: A
authors: Al-Jadaa
authors: Clinic of Preventive Dentistry, Periodontology and Cariology, Center for Dental Medicine, University of Zurich, Zurich, Switzerland.
authors: Thomas
authors: T
authors: Attin
authors: Oral and Maxillofacial Unit, Tampere University Hospital, Tampere, Finland.
authors: Timo
authors: T
authors: Peltomäki
authors: Clinic of Preventive Dentistry, Periodontology and Cariology, Center for Dental Medicine, University of Zurich, Zurich, Switzerland.
authors: Patrick R
authors: PR
authors: Schmidlin
mesh_terms: D015921:Dental Implants / Q000382:microbiology*; D003763:Dental Leakage / Q000175:diagnosis* / Q000382:microbiology*; D013293:Enterococcus faecalis; D066298:In Vitro Techniques; D008422:Materials Testing; D013499:Surface Properties
chemical_list: D015921:Dental Implants
keywords: abutment; implants; in vitro; leakage; sealability