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The purpose of this study was to investigate the vertical marginal discrepancy (VMD) and residual excess cement (REC) of cementable and screwmentable monolithic zirconia crowns cemented with different types of cement. Abutments were attached to 40 implant analogues. Crowns were created using computer-aided design/computer-aided manufacturing technology from monolithic zirconia blocks, either with or without a screw access hole (SAC). Crowns created both ways were split into two groups and cemented with resin and zinc polycarboxylate cement under a 5-kg weight. VMD and REC values were evaluated using an X20 zoom stereomicroscope. Data were analysed using two-way ANOVA and the Bonferroni test. According to the two-way ANOVA results, REC measurements differed significantly in the crown design and cement groups. However, whilst VMD values were significantly different in both crown design groups, there was no significant difference in the cement groups. According to the Bonferroni test results, the highest REC (157.241 ± 44.29 µm) and VMD (68.052 ± 16.19 µm) values were found in the crowns without SAC and cemented with zinc polycarboxylate. Screwmentable crowns are more effective than cementable crowns in reducing REC and VMD. Whilst polycarboxylate cement reduces VMD in screwmentable crowns, resin cement is more suitable for cementable crowns., (© 2024. The Author(s), under exclusive licence to The Society of The Nippon Dental University.)

Aim: Temporary cement can be applied for both permanent and temporary cementation of implant-supported fixed restorations. These cements must have certain physical and mechanical properties. Specifically, the film thickness directly affects the cement's clinical success. The aim of this study was to evaluate and compare the film thicknesses of six temporary cements before and after thermal cycling., Materials and Methods: Eighty-four metal copings with uniform holding loops were fabricated and divided into 12 groups of seven samples each. Six of these groups were subjected to a thermal cycling process. The copings were cemented to solid implant abutments (Implance Solid Abutment, 3.5-mm cervical diameter, 2 mm high, 6° taper, Implance Dental Implant System; AGS Medical, Trabzon, Turkey), using six different types of cement. The fitting surfaces were coated with the luting cements. After steeping in artificial saliva for 24 hours, the specimens were subjected to pull-out testing using an Instron machine. Specimens in the thermal cycling groups were subjected to 700 thermal cycles (36-55°C) prior to pull-out testing., Results: The Mann-Whitney U test revealed significant differences between the retention values of the thermal cycling (+) and thermal cycling (-) groups (U = 153.0, P < 0.01). The retention values of the groups subjected to thermal cycling were significantly lower than those of the cements that were not subjected to thermal cycling. Thermal cycling also affected the film thickness significantly (Wilcoxon signed rank test, Z = -5.533, P < 0.001)., Conclusions: Thermal cycling affects the film thickness and retention of temporary cements significantly. The retention value was significantly higher for glass ionomer cement than for the other cements tested, and this cement also exhibited greatest film thickness., Competing Interests: There are no conflicts of interest