Scanning Electron Microscope Analysis of Adhesively Bonded Two-piece Abutments versus One-piece CAD/CAM Zirconia Abutments

Objectives: The aim of this study was compare two CAD/CAM zirconia abutments (1-piece abutment versus 2-pieces adhesively bonded abutment) for contamination, traces of processing and microscopic gaps. Material and methods: Three groups consisting of five identical abutments were cleaning with a steam jet and ethanol and then scrutinized by a scanning electron microscope (LEO 1530 VP; Oberkochen, Germany). The first group (1) contained individual CAD/CAM abutments (Atlantis™; Dentsply Implants, Molndal, Sweden); the second group (2) contained adhesive bases before they were connected to their copings (Astra Tech Cast Design 4.5; Dentsply Implants) while the third group (3) contained the same adhesive bases but with a zirconia coping attached (Ceramill ZI; Amann Girrbach, Pforzheim, Germany). Results: All abutments in groups 1 and 3 and 4 out of 5 abutments in group 2 were found to be contaminated. Traces of processing were found only on the abutments in group 3. No microscopic gaps were present in groups 1 and 2. All 2-piece abutments in group 3 exhibited extensive bonding gaps that were unfilled, measuring 213 to >3,000 μm horizontally and 42 to 101 μm vertically. Conclusions/Clinical relevance: Both the instances of contamination and the microscopic gaps of the 2-piece abutments could cause damage to the hard and soft tissues around the implant. This topic would merit further investigation.