Purpose: The aim of this study was to compare the bacterial leakage of conical internal connection implants with different taper angles (5.4, 12, 45, and 60 degrees) and examine the efficiency of a disinfectant agent and a silicone sealant agent in the prevention of bacterial leakage under loaded conditions. Materials and Methods: Twenty-one implant-abutment connections were studied from each implant system (Ankylos Implants, Dentsply; Bego Semados S Implants, Bego; Trias Implants, Servo-Dental; DTI Implants, DTI), for a total of 84 implants. Each system's implants were divided into three groups as follows: unsealed (control), 2% chlorhexidine gel-sealed, or silicone-sealed (n = 7 for each group). The insertion torque was applied to each abutment screw according to the manufacturers' recommendation. The specimens were partially immersed in an 8-mm E faecalis suspension. A cyclic load of 50 N was applied for a total of 500,000 cycles at 1 Hz to the specimens. Following disconnection of dental implants and abutments, microbial samples were taken from the inner threaded surface of the implants, plated, and counted under appropriate conditions. Results: There were no statistically significant differences in frequency of bacterial leakage and leaked bacterial counts among the four types of connections in all groups (P > .05). The statistically significant differences were found between sealant agents and control groups in four different connection types in terms of the amount of leaked bacteria (P .05). There was no significant difference between the amount of leaked bacteria for four connection types when comparing the chlorhexidine and silicone sealant agents (P > .05). Conclusion: Differences in taper angles in the internal conical connections had no significant effect on leaked bacterial counts or the frequency of bacterial contamination under dynamic loading. The application of 2% chlorhexidine gel or a silicone sealant can reduce the leaked bacterial counts and reduce the frequency of bacterial leakage. Keywords: bacterial leakage, dynamic loading, implant-abutment connection, sealant