In Vitro Microbiological Analysis of Bacterial Seal in Hybrid Zirconia Abutment Tapered Connection.

Purpose: The aim of this study was to evaluate the bacterial seal at the implant-hybrid zirconia abutment interface and Morse taper-type connections through in vitro microbiological analysis.
Materials and Methods: Sixteen implants and their respective abutments were divided into 3 groups: test (10 sets), positive control (3 sets), and negative control (3 sets). In the test group, 10 implants were contaminated with Escherichia coli using a sterile inoculating loop to the inner portion of the implants, followed by torque application to the abutment (30 N·cm). The positive controls were also contaminated, but no torque was applied to the abutment screw. The negative control consisted of uncontaminated sets. All specimens were immersed in test tubes containing 5 mL brain heart infusion (BHI) broth, maintained in a microbiological incubator for 14 days at 37°C under aerobic conditions, and monitored every 24 hours for evidence of bacterial growth.
Results: During the 14 days of incubation, no significant increase in the number of cloudy culture media was observed in the test group (P = 0.448). No significant difference in broth turbidity ratio was observed (P > 0.05).
Conclusion: Hybrid zirconia abutments can create an effective seal at the tapered abutment-implant interface with a 30-N·cm installation torque.