Comparison and Accuracy of Different Impression Procedures Utilizing Hex and Non-Hex Impression Copings

Accurate impressions are essential to ensure passive fit in implant-supported prostheses. Factors, such as coping design and implant angulation, can significantly influence impression accuracy.

To compare the accuracy of different impression procedures using Hex and Non-Hex impression copings in multiple implant conditions with varying angulations.

An in vitro study was conducted using three mandibular edentulous acrylic models representing implant angulations of 0°, 5°, and 10°. Two dummy implants were inserted in each model at designated angulations. Hex and Non-Hex copings were used in three configurations: Hex-Hex, Hex-Non-Hex, and Non-Hex-Non-Hex. Impressions were made using the open-tray technique and splinted copings. A total of 42 impressions were recorded. Master casts and reference models were scanned using a Medit T300 scanner, and deviations were measured in mesiodistal (X), buccolingual (Y), and vertical (Z) axes using Blender for Dental software. Statistical analysis was performed using SPSS v21.0.

The Non-Hex-Non-Hex configuration showed the least deviation across all three axes in 5° and 10° angulated models. The Hex-Hex combination consistently recorded the highest deviation values. Differences in impression accuracy were statistically significant (P < 0.05) across all axes, especially in angulated conditions.

Non-Hex impression copings provide superior accuracy in multiple and angulated implant impressions. Their use is clinically recommended in nonparallel implant conditions to enhance prosthetic fit.