Effects of cementation technique and cement thickness on the retention and amount of excess cement in implant-supported restorations

Purpose

To assess the amount of excess cement and the retentive strengths of two different cementation techniques (conventional cementation and practice abutment) using copings fabricated with three different cement thicknesses (20 μm, 35 μm, and 50 μm).

Materials and methods

Thirty zirconia copings were fabricated on screw retained abutments and randomly divided into three equal groups (n = 10) according to the cement thickness (20 μm, 35 μm, and 50 μm). Each group was cemented with tow cementation techniques. Cementation was performed with provisional cement (Temp-Bond). In the conventional cementation technique, cement was applied until each coping was approximately half filled, and the copings were subsequently placed on the implant–abutment assembly. Then, the copings were cleaned and cemented using the practice abutment cementation technique to remove excess cement prior to the process. Each technique was performed using copings with three different cement thicknesses (20 μm, 35 μm, and 50 μm). The specimens with the cemented copings were weighed on a high-precision analytical balance before and after removing the extruded cement, and the differences between the two measurements were calculated. Then, each specimen was subjected to a pullout test using a universal testing machine. The load required to dislodge the coping was recorded. The data were analyzed using two-way and one-way analysis of variance and independent sample t tests at a significance level of 0.05.

Results

The highest retention values were obtained for 20 μm cement thickness in the conventional technique and the practice abutment cementation technique. The amount of excess cement was the highest for the 50 μm cement thickness obtained for both cementation techniques, whereas the lowest mean values were recorded for the 20 μm cement thickness.

Conclusion

The conventional cementation technique is recommended over the practice abutment technique to increase the retention of crowns cemented with provisional cement. However, care must be taken to remove the extruded cement. A cement thickness of 20 μm is preferable for enhancing the retention of cemented crowns and for reducing the amount of excess cement when applying both conventional and practical abutment cementation approaches.