Statement of problem
Cement at the restorative margin after implementation of the manufacturer’s recommended
procedure for cement cleanup has not been extensively evaluated.
The purpose of this in vitro study was to use microcomputed tomography (μCT) to evaluate
the number, volume, and width of voids left at the margin when dental cement is cleaned
during the cementation process as per 2 manufacturer-prescribed methods for cement
cleanup by evaluating a self-adhesive resin cement and a resin-modified glass ionomer
Material and methods
Twenty molar Ivorine Typodont prepared teeth were scanned, and lithium disilicate
crowns were milled and cemented to the prepared teeth as per the manufacturer-recommended
cementation process. Two methods of cement cleanup were performed: the excess cement
was tack-polymerized with a polymerization light, or a delay of 3 minutes was used
for the excess cement to reach partial polymerization, and the excess cement was removed
with a sharp sickle scaler. These 2 methods of cement cleanup were performed with
2 cements: a resin-modified glass ionomer cement and a self-adhesive resin. Each specimen
was then scanned with a μCT machine. The buccal margin of each specimen, from mesiobuccal
line angle to distobuccal line angle, was examined, and the number, volume, and width
of any voids remaining at the margin open to the environment were measured. For statistical
analysis, the specimens were first grouped by method of cement cleanup and then grouped
by cement type. The Wilcoxon ranked sum test was implemented because of the lack of
a normal distribution and the heterogeneity of the data (α=.05).
No statistically significant difference was found in the median number of voids, median
volume of voids, or median width per void between the 2 cleanup methods, irrespective
of cement type (P>.05). Significant differences were found in the median number of voids, median volume
of voids, and median width per void when comparing cement types, irrespective of cement
cleanup methods (P<.05).
The choice of cement may be more important than the method of cement cleanup when
considering voids left at the margin. Microcomputed tomography is an excellent nondestructive
tool for volumetric measurements of voids at the margin.