RESUMO
Background This in vitro study aimed to assess the vertical disparities in the positioning of complete crown castings when different quantities of cement were used and to determine the optimal amount of cement for cementation while minimizing any marginal discrepancies. Methodology A total of 60 ideal nickel-chromium (Ni-Cr) crown castings were divided into three groups of experimental volumes of glass ionomer cement, with 20 castings in each group. Group I had completely filled volume with cement, group II had it half-filled, and group III had brushed up cement internally. The crowns were cemented by applying a static load of 5 kg to the cementation apparatus for 10 minutes. The marginal discrepancy between the die and the castings was measured pre-cementation and post-cementation using image analysis software in combination with a stereomicroscope (Motic, USA) at predetermined points that were marked on the die. Statistical analysis was performed using Statistical Package for the Social Sciences (IBM SPSS Statistics for Windows, IBM Corp., Version 16, Armonk, USA) software. A one-way analysis of variance (ANOVA) was used for the intergroup analysis. A paired sample t-test was used for intragroup analysis. Result Brushing cement onto the internal surface presented the least mean values (P<0.05) of post-pre-cementation vertical discrepancy (14.92±10.77 µm) when compared to the half-filled cement group (28.42±12.45 µm) and the fully-filled cement group (58.50±20.91 µm). Conclusion Cement volume appeared to be a key factor in the vertical marginal discrepancy of the crown. The cement brush applied to the internal surfaces of the crown showed smaller post-cementation vertical discrepancies.
