Objectives: Compare effects of immediate vs. delayed cement removal time on the quality of the cement at the margin using four adhesive resin cements and one control.

Methods: A simulated clinical situation was used test the cement removal as a function of time of four resin adhesives, Calibra, Cement-It , Panavia  F, and RelyX ARC and a control, C&B Metabond . Stainless steel crowns were fit to  ivorine dies (100 pairs) to simulate both open and closed margins. One clinician performed all the procedures. Cement was removed at two time periods: immediately after seating and a delayed time specified in the handling instructions. Two independent evaluators rated: 1) amount of excess cement at the margin 2) quality of the cement at the margin, and 3) number of specimens with cement pullouts. Evaluator reliability was determined with Kendall's coefficient (p<0.05). Amount of cement and quality of marginal seal vs. removal conditions were analyzed with both  Kruskal-Wallis Test and two-way ANOVA with  Tukey HSD multiple comparison test (p<0.05).  Wilcoxon Signed Rank tests and paired t-tests were used to compare  between quality of seal, presence of voids, and cement pulled from the open vs. closed margin (p<0.05).  Note: large sample size meant both statistical analyses methods were valid.

Results: Assessment at the early removal time revealed RelyX ARC rating (0.2±0.3) was significantly lower than the ratings for  C& B Metabond (1.4±0.7)and Panavia F(1.6±1.1). Panavia F specimens exhibited the most excess cement at both removal times. At the delayed time, major distinctions were found among the cements for ease of manipulation; Calibra was rated the easiest and C&B Metabond was rated most difficult.

Conclusion: This study demonstrated that the cements could be removed, immediately after seating, with no apparent adverse affect.

ACP/ESPE Fellowship in Geriatric Prosthodontics and Cement manufacturers.