Wear of Morse taper and external hexagon implant joints after abutment removal.

The aim of this in vitro study was to evaluate the removal torque values on abutments and the morphological wear aspects of two different dental implant joints after immersion in a medium containing biofilm from human saliva. Twenty implant-abutment assemblies were divided into four groups in this study: (A) Morse taper free of medium containing biofilm, and (B) after contact with a medium containing biofilm from human saliva; (C) External Hexagon free of medium containing biofilm, and (D) after contact with medium containing biofilm from human saliva. The abutments were firstly torqued to the implants according to the manufacturer´s recommendations, using a handheld torque meter. Groups B and D were immersed into 24 well-plates containing 2 ml BHI medium with microorganisms for 72 h at 37 °C under microaerophilic conditions. After detorque evaluation, the abutments were removed and the implants were analyzed by scanning electron microscopy (SEM) and profilometry. On the detorque evaluation, the torque values decreased for the external hexagon implants and increased for the Morse taper implants. However, the values were lower when both implant-abutment assemblies were in contact with a medium containing biofilm from human saliva. The wear areas of contacting surfaces of the implants were identified by SEM. The highest average roughness values were recorded on the surfaces free of biofilm. The medium containing biofilm from human saliva affected the maintenance of the torque values on Morse taper and external hexagon abutments. Additionally, the removal of abutment altered the inner implant surfaces resulting in an increase of wear of the titanium-based connection.

Biofilm Affecting the Mechanical Integrity of Implant-Abutment Joints.

PURPOSE: This in vitro study evaluated the effect of biofilms on abutment torque loss and wear of implant internal connection surfaces. MATERIALS AND METHODS: Morse taper abutments were torqued to corresponding implants and then the implant-abutment assemblies were immersed in a biofilm medium for 72 hours. After detorque evaluation, the abutments were removed and the inner implant surfaces were observed via scanning electron microscopy and profilometry. RESULTS: The removal torque values and the implant damaged areas decreased after contact with biofilms. CONCLUSION: The lubricating effect of biofilms decreased the friction between contacting surfaces, negatively affecting the mechanical integrity of the implant-abutment connection.