Implant cast accuracy as a function of impression techniques and impression material viscosity

Area of Science:

• Dental Materials Science
• Prosthodontics
• Implant Dentistry

Background:

• Accurate fabrication of dental restorations relies heavily on the precision of casts made from impressions.
• The choice of impression technique and material can influence the dimensional accuracy of these casts.

Purpose of the Study:

• To compare the accuracy of dental casts produced using different impression techniques.
• To evaluate the impact of impression material viscosity on cast accuracy for implant restorations.

Main Methods:

• Closed-tray impressions were made at the implant level (indirect, metal copings) and abutment level (direct, plastic caps).
• Medium-body or heavy-body polyether impression material was used.
• Cast accuracy was measured using a microscope and compared to the master model.

Main Results:

• Impression material viscosity (medium vs. heavy body) showed no significant effect on cast accuracy.
• Indirect impressions with metal copings resulted in significantly more accurate casts than direct impressions with plastic caps.
• Plastic caps led to larger inter-abutment distances (0.19%-0.24% difference), while metal copings showed minimal differences (-0.06% to 0.02%).

Conclusions:

• Impression material viscosity is not a critical factor for implant cast accuracy.
• Indirect impression technique with metal implant-level copings provides superior cast accuracy compared to direct abutment-level impressions with plastic caps.
• This finding is particularly relevant for fabricating complex multiple-implant supported restorations.