Preliminary Experimental Study On The Micro-leakage At Dental Implant-Abutment Interface (IAI)

Background: As a maturing oral rehabilitation technique, dental implant hasbeen accepted by more and more patients as a routine way to restore missingteeth. Peri-implantitis is a common and hazardous complication after implantsdenture restoration, the symptoms of which can be characterized as repeated softtissue inflammation around the dental implant, continuous bone absorption anddental implant loss at its final phases. Etiology of peri-implant inflammation hasbeen well studied in recent years, though the hypothesis that micro-leakageoccurring at Implant-Abutment Interface (IAI) may induce the inflammationremains controversial. To the best of authors’ knowledge, existing studies onmicro-leakage tend to be qualitative analysis. However, due to sample variationand inconsistent leakage detection markers, these results could hardly reach anyconsensus. Only a few quantitative analyses use gram-negative bacteria or color pigment as the micro-leakage detection marker, but the sizes of these markers areusually bigger than the gaps and may not truly reflect the preciseimplant-abutment interface (IAI) micro-leakage at molecular level.Objectives: In this study, we use endotoxin, a molecular biomarker and thedynamic turbidity testing method to detect the micro-leakage of the internal andexternal-connection implants currently used at the Third Affiliated Hospital,School of Stomatology, Fourth Military Medical University. Implant-abutmentconnection types, their respective micro-leakage, and GapSeal gel sealingcapability were evaluated and discussed. Endotoxin is an etiological factorresponsible for peri-implantitis, the molecular weight of which is far less than thebacterial. Compared with the existing micro-leakage detection methods,endotoxin provides much higher accuracy.Material and Methods: The present study is composed of three parts.1) Toset up the implant-abutment micro-leakage testing model and select the properreagent sensitivity of Tachypleus Amebocyte Lysate (TAL) for endotoxinconcentration determination.2) To compare the difference of implant-abutmentinterface micro-leakage among different dental implant brands used by School ofStomatology, Fourth Military Medical University. The result may providereference for clinical practice while lay up the foundation for further measures toreduce the micro-leakage.(C) To evaluate the sealing capability of GapSeal gel.The evaluation contains two aspects:1. Sealing capability before and afterapplying the GapSeal.2. Comparison of leakage among the implants afterapplying the gel.Results:(1) Micro-leakage at IAI is inevitable. The leakage exists in all implantssystems, regardless of the "Morse taper","platform switch" or any other IAI connection types. Internal connection implants present a significant lowerleakage, but this leakage couldn’t be eliminated.(2) In our experimental study, our preliminary results showed that implantsof external connection type (Nobel Br nemark) presented higher micro-leakagethan their internal counterparts (Nobel Replace, Straumann Standard Plus). Thevolume significantly increased in all groups as time went by, the differencebetween the groups gradually reduced while still presented statisticallysignificant.(3) The GapSeal gel did not completely eliminate the occurrence ofmicro-leakage. However, after the application of GapSeal gel, leakage wassignificantly reduced; both internal and external connection implant presented nostatistically significant difference after the application of GapSeal.Conclusion：As a prevalent phenomenon, micro-leakage occurred at dentalimplant-abutment interface can not be eliminated, however, differences existamong different connections, the sealing gel can not eliminate the micro-leakagecompletely.