Impression Copings, Impression Pins, Impression Abutments or Impression Posts – they all mean the same.
These are used to register the depth and orientation of the Implant inside the bone as it relates to the surrounding teeth so that the laboratory can fabricate the crown/ Final Prosthesis.
Closed Tray – this part is screwed into the implant and a traditional Impression is taken over this part. When the material is dried in the mouth – the impression tray is removed. An impression of the part is left inside the material. The tray is sent to the laboratory who in turn reverse pours a model into a replica of the teeth and now can build the final prosthesis to screw into the implant. The closed tray Impression coping is then unscrewed and kept by the doctor for possible future use after sterilization.
Open Tray – same process except that the coping tray stays inside the tray and goes to the lab - this make the labs job easier and is more accurate – because the lab can attach the analog to the open tray providing the exact position and creating the mouth replica at the same time/step.