An evaluation of impression techniques for multiple internal connection implant prostheses

Area of Science:

• Dental Materials Science
• Prosthodontics
• Implant Dentistry

Background:

• Open-tray impression techniques for multi-unit implant restorations can lead to inaccuracies.
• Movement of impression copings within the material can compromise the 3D spatial orientation transfer.
• Restoration fit issues may necessitate corrective procedures.

Purpose of the Study:

• To evaluate the accuracy of three different impression techniques for multi-unit implant restorations.
• To compare the precision of definitive casts obtained using polyether impression material.
• To assess techniques for multiple internal connection implants.

Main Methods:

• Three groups of polyether impressions were made using modified and non-modified square impression copings.
• One group utilized copings joined with autopolymerizing acrylic resin (R group).
• Definitive cast accuracy was measured using a profile projector and compared to a reference model.

Main Results:

• Significant differences in accuracy were found among the three impression techniques (P < .001).
• The resin-joined coping group (R) demonstrated significantly higher accuracy than non-modified (NM) and modified (M) groups.
• Cast inaccuracies were smaller in the R group (18.17 µm posterior, 15.23 µm anterior) compared to M and NM groups.

Conclusions:

• Joining square impression copings with autopolymerizing acrylic resin improves definitive cast accuracy.
• This method enhances the precision for multi-unit implant restorations with internal connection implants.
• The findings suggest a more reliable impression technique for complex implant cases.