Effects of cement application techniques on implant-supported single crowns

To investigate the effect of different cement application techniques on weight of cement, cement film thickness, and retention force of cement-retained implant-supported single crowns.

Thirty-two samples comprising a titanium abutment analogue and a lithium disilicate crown were prepared and randomly divided into four groups. After surface pre-treatments, crowns were luted to abutment analogues with resin cement, adopting four application techniques: margin of crown (MA), brush on crown (BA), gross application on crown (GA), and pre-seating with chair-side copy abutment (CCA). Weight of cement used was recorded, while the cement film thickness was measured on digital files acquired by Micro-CT. Crown dislodging forces were assessed via the tensile test, after which failure modes were observed and analysed.

CCA group (20.162 ± 2.385 mg) had a significantly lower cement usage than MA (26.149 ± 0.875 mg), BA (25.248 ± 0.644 mg), and GA (25.198 ± 1.226 mg) (P < 0.001). BA (187.06 ± 23.77 µm) presented significantly higher cement film thicknesses than those using other application techniques (155.20 ± 13.44 µm for MA, 152.39 ± 25.32 µm for GA, and 135.73 ± 27.42 µm for CCA) (P= 0.047, 0.027, and < 0.001, respectively). Four groups had comparable dislodging force with no significant difference on failure mode (P = 0.897).

Cement application techniques significantly influenced the weight of cement and cement film thickness on implant-supported single crowns, while the crown dislodging force was not affected. Based on the study result, CCA technique was recommended for cementing implant-supported crowns. A new model was developed for the retention test of anatomical crowns.

Cement-retained implant restorations are prone to complications induced by excess cement which can compromise clinical outcomes. The study evaluated the factor of cement application technique, proposing the CCA technique for its optimal balance in cement usage, crown retention, and clinical efficiency.