Background and aim: Temporary restoration is one of the important phases of treatment in patients requiring fixed dental prosthesis. The materials used to construct these restorations should have satisfactory physical properties. The purpose of this study was to investigate the effect of temporary restorative materials Acropars in comparison with Trim on periodontium. Materials and methods: In this study, the effect of temporary restoration was measured on periodontium using the Loe & Silness Gingival Index (GI) with the Williams periodontal probe in the first week and the first month. Periodontist, who was blind to study, examined the GI. All of the obtained measurements were recorded. In this study, 40 tooth surfaces were measured for each group to determine the effect of Acropars and Trim on periodontium. Before crown preparation, the patients were examined and asked to record the medical history in order to ensure that no systemic problems were present, so that the patients were not involved with any periodontal disease and even had no history in this regard. The effects of a material were compared between the first week and the first month by Wilcoxon test, and the difference between the two materials was compared with the Mann Whitney test. Results: In this study, GI showed a statistically significant difference in the first week and the first month between Acropars and Trim. The GI showed a significant difference in the axial surface of Acropars between the first week and the first month, but this difference was not significant at proximal surface. The GI in both Acropars and Trim had no significant difference in the axial surface in the first week, but revealed statistically significant difference in the proximal surfaces in the first week and the first month. Conclusion: The results showed that the Trim clinically has better properties than Acropars. Features such as non-smooth surface and inappropriate marginal fit of Acropars showed their own clinical manifestations as gingivitis, mostly in the interdental areas. However,the Acropars can be used as it is available and cheaper but should take care of oral hygiene, controlling the plaque of patients and having more precision by a dentist in constructing a good interim restoration, preferably an indirect method.
