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BACKGROUND: There are many studies on the marginal integrity of all ceramic crowns with different resin adhesives, or different shoulder, different polymerization angles, but there is no research on whether different methods of redundant bonding will affect the marginal integrity of all ceramic crowns. OBJECTIVE: To analyze the effect of removing excess resin adhesive on the marginal integrity of all ceramic crowns with different marginal gaps. METHODS: Totally 40 extracted third molars were prepared with all ceramic crowns and randomly divided into groups A, B, C, and D (10 teeth in each group). After the model scanning was completed, the edges of restoration in groups A, B and C were lifted at 30, 60 and 90 µm respectively by computer control, while those in group D were not raised. Procera alumina CAD-CAM all ceramic crowns were made. Then, the four groups of groups A, B, C and D were randomly divided into two subgroups. In one subgroup, a large amount of excess resin adhesive was removed with a small brush, and then the light was illuminated for 40 seconds after the full crown bonding. Subsequently, a small amount of resin adhesive was scraped off with sickle scalpel (small brush group). The sample in the other subgroup was exposed to light for 2 seconds, scraped off with sickle scalpel, and then illuminated for 40 seconds (sickle group). The marginal integrity and surface quality of the adhesive were observed by scanning electron microscope. RESULTS AND CONCLUSION: (1) Scanning electron microscope showed that the continuity of the bonding interface was better in the small brush group. Different degrees of adhesive defects were found in the sickle group. Under the same marginal gap, the defect rate of cement in the small brush group was lower than that in the sickle group (P < 0.05). Under the same adhesive removal method, there was no significant difference in the defect rate of cement between groups A, B, C, and D (P > 0.05). (2) Results indicate that the method of using small brush to remove excess adhesive, then lighting for 40 seconds, and finally using sickle scalpel to remove the remaining small amount of adhesive is more suitable for clinical practice. [ABSTRACT FROM AUTHOR]