An In Vitro Investigation of Gas and Dye Leakage at the Implant-Abutment Junction Using Titanium and Cobalt Chrome-Based Abutments

The lack of integrity at the implant-abutment junction (IAJ) contributes to problems such as micromovements and microbial colonization. This study aimed to (1) design a protocol for assessing microleakage at the IAJ using chromophore analysis that hasn’t been involved in other analysis, (2) compare gas and dye leakage using titanium (Ti) and cobalt chrome (CoCr) abutments, and (3) assess the effect of gold (Au) gilding on sealing. Forty abutments were divided into five groups: milled Ti (MTi); cast CoCr (CCoCr); milled CoCr (MCoCr); cast CoCr with Au gilding (CCoCrG); and milled CoCr with Au gilding (MCoCrG). Samples were connected to a pressurised gas and dye reservoir. Chromophore analysis using crystal violet was performed via UV-Vis spec-trometer to calculate leakage concentration. Scanning electron microscopy (SEM) analysis assessed surface morphology which revealed an intimate contact with the MTi and MCoCr but irregularities at the CCoCr abutments. Results showed gas leakage in CCoCr and MCoCr groups, while no true dye leakage occurred in MTi, MCoCr and MCoCrG assemblies. CCoCr exhibited the poorest seal; however, Au gilding improved the seal in these samples. Chromophore analysis using crystal violet provided an ac-curate quantitative assessment. Milled abutments demonstrated significantly less mi-croleakage than cast (non-gilded) versions, Au gilding effectively reduced leakage.