Clinical Compromises That Necessitate Cement Removal Following Curing
Avishai Sadan, DMD
The use of porcelain laminate veneers is one of the most popular and predictable treatment modalities in aesthetic dentistry. Due to the brittle nature of unbonded porcelain and the negative effect of contaminants on bond strength, however, this procedure still presents a unique clinical challenge. The attention to detail required in every clinical and laboratory step makes these procedures extremely technique-sensitive. Porcelain veneers are generally bonded with light- or dual-cure resin cements. The removal of excess set resin cement is a labor intensive and time-consuming procedure. Consequently, cement manufacturers recommend the thorough removal of all excess prior to curing. Are there instances in which the clinician may choose to remove the excess once curing has been completed, and if so, what would be the correct manner to remove such excess?
There are two instances that may force the clinician to leave excess cement prior to curing, and each constitutes a clinical compromise. In the first, the removal of the excess may cause bleeding around the preparation. This area, which may be a pinpoint inflammation, is more appropriately left undisturbed during cementation. The second instance is directly related to the marginal fit of the veneer. In a study conducted by Burgess et al, two types of veneers were fabricated. The first had margins that demonstrated optimal fit; the second had open margins. Both types were bonded in two different techniques. In the first, which simulates the general recommendations, the veneer was seated, the excess was thoroughly removed, and the cement was cured. In the second instance, the veneer was seated, the cement was cured prior to the removal of any excess, and the excess was removed once curing was accomplished. In the well-fitting margins group, no differences in the marginal integrity were found between the two techniques. In the open margins group, however, cleaning the cement prior to curing created a marginal deficiency, while cleaning the cement after curing resulted in significantly improved marginal integrity. If a pinpoint area is determined to possess a marginal fit that is slightly less than ideal, yet is still within the range of being clinically acceptable, the clinician may elect not to remove the excess around this area prior to curing in order to improve the marginal integrity.
Set resin cement is removed more efficiently with hand instruments; a number 12 surgical blade (semilunar shape) is recommended. The number 12b blade can inflict injury upon the clinician and should be avoided. The blade is placed beneath the excess set resin and “flakes” off the excess. This process is accomplished
with firm and well-controlled strokes while firmly pressing the blade against the tooth surface. The strokes are always directed coronally from the sulcus. The procedure is completed when no surface irregularities can be detected in the margins with the explorer tip. Due to the sharp nature of surgical blades, extreme caution must be exercised to prevent the damage of the supporting tissues. Once refined, this technique enables the clinician to remove excess set resin in a rapid and predictable fashion.
*Dean, Ostrow School of Dentistry, University of Southern California