DENTAL IMPRESSION COPINGS:
“Dental impression coping is manufactured device which is used to copy the exact shape and position of a dental implant abutment interface in the impression for accurate positioning of dental implant analogue in the working model.”
Impression coping facilitate the dentist to transfer the location of implant on laboratory cast exactly to the same position. Dental Impression Copings can be screwed either to body of implant or an implant abutment.
Impression copings are almost same if width, length and depth are considered.
Ideal material for impression coping are:
- Anodized aluminum
The impression transfer can be done by two techniques:
- Closed tray technique
- Open tray technique
Closed tray technique captures the index of impression coping and after the removal of impression from mouth the coping is unscrewed and placed with implant analogue into impression back.
While, open tray technique replicates a peculiar impression coping that is designed to achieve through impression tray. After removal of impression from mouth, coping is unscrewed and pulled out in impression. This transfer has high degree of accuracy.
- when planning large span frameworks
- when implants are too divergent
A radiograph is necessary to confirm the position of implant platform otherwise incorrect location of improperly seated coping is transferred. After the completion of impression transfer, implant analog is screwed onto coping to facilitate laboratory cast fabrication.
- Closed tray impression copings
- Open tray impression copings
- Press-Fit impression copings
- Mini implant impression copings
- Impression coping for multi unit
- Snap-On impression coping transfer
Problems associated with impression coping:
- Along with all benefits, impression coping has a drawback that it may magnify the convergence of implants
- Thus, standard impression copings do not fit on the mis angled implants due to convergence.