Aim: The higher success rate (>90%) of dental implants over 5 years has made this treatment option favorable for dental surgeons as well as for patients. The present in vitro study was conducted to assess microleakage and microgap of two dissimilar internal implant–abutment associations. Materials and methods: Forty dental implants were divided into two groups: trilobe internal connection fixtures in group I and internal hexagonal geometry fixtures in group II. For the immersion of implant abutment assemblies, sterilized tubes containing 4 mL of Staphylococcus aureus broth culture were incubated at 37°C for 2 weeks. Gram's stain and biochemical reactions were used for identification of colonies. Results: The mean log₁₀ colony-forming unit (CFU) in group I was 8.6 and was 9.3 in group II. The disparity among two groups was found to be significant (p < 0.05). The mean microgap in group I was 7.2 μm and was 10.4 μm in group II. The disparity among the two groups was found to be significant (p < 0.05). Conclusion: Authors found that microscopic space between implant and abutment may be the site of penetration of bacteria. There was significant higher log₁₀ CFU in dental implant fixtures with an internal hexagonal geometry compared to the dental implant fixtures with a trilobe internal connection. Clinical significance: Microscopic space between implant and abutment may be the site of penetration of bacteria. This information will help to avoid microleakage to improve implant success rate.