Minimizing excess cement around implant restorations: an in vitro study of cementation techniques

Excess cement around cement-retained implant crowns is associated with a higher incidence of peri-implantitis, but there are limited data to indicate which cement application technique minimizes excess cement. The purpose of this in vitro study was to evaluate the amount of excess cement that resulted from different cement application techniques. Fifty identical titanium custom abutments and monolithic zirconia crowns were digitally designed and milled in the shape of a maxillary first molar. Ten crowns were cemented by applying temporary cement only to the intaglio coronal surface of the crown; these specimens were used as a control group to determine the amount of cement to be used in all other groups. Four different cement application methods were evaluated (n = 10): wall layer technique, in which cement was brushed on the intaglio axial walls of the crown; precementation technique, in which cement was applied to the intaglio coronal aspect of the crown, and the crown was precemented on an abutment replica, quickly removed, and then repositioned on the milled abutment; rim application, in which cement was applied to the cervical marginal rim of the crown; and increased cement space, in which the cement space was increased to 60 μm (compared with 40 μm in other groups) and cement was brushed on the intaglio coronal surface. Digital photographs of the cemented crowns were taken, and image editing software was used to measure the displacement of excess cement, that is, the distance that it traveled below the finish line on the mesial, distal, buccal, and lingual surfaces. Excess cement was then removed from each specimen and weighed. An analysis of variance test was used to evaluate the difference among groups, and each pair of groups was compared with the t test. Compared with all of the other experimental groups, specimens cemented with the wall layer technique showed a significantly smaller amount of cement excess in terms of both the distance traveled and weight (P < 0.05). Based on the findings, the wall layer cementation technique, in which cement is brushed on the intaglio walls of the crown, is recommended to reduce excess cement around implant crowns.