In vitro evaluation of controlled-release 14% doxycycline gel for decontamination of machined and sandblasted acid-etched implants

Background: Peri-implant infections are associated with the establishment and maturation of a bacterial biofilm characterized by a predominance of Gram-negative fusiform anaerobic species. The decontamination of implant surfaces is then crucial for a successful peri-implant therapy. Methods: Twenty-one smooth and 21 rough implants, divided into four groups according to surface and treatment modality, were contaminated with Streptococcus sanguinis and then placed in an incubator with the atmosphere of 5% CO2 at 37◦C for 24 hours to allow the bacteria to grow. After 24 hours, the test groups were treated with controlled release 14% doxycycline gel injecting the gel circumferentially over the surface of the implant for 3 minutes, while the control groups were irrigated with sterile saline for 1 minute. The implants were then vortexed into triptych soy broth to allow the bacteria to detach from the surface, diluted 1:100 and plated. Colony forming units (CFU) were counted 48 hours after incubation. Results: The use of a 14% doxycycline gel minimized CFU counts compared to control groups, with the difference being statistically significant (P < 0.05). The reduction of CFUs in the smooth test group is more marked than in the rough test group, but the difference doesn't reach statistically significance (P = 0.215). Conclusions: The use of 14% doxycycline gel in implant surface decontamination was efficacious in this in-vitro study. Adjunctive use of locally delivered 14% doxycycline gel might be a viable option in the management of peri-implantitis and peri-implant mucositis considering its efficacy in reducing bacterial colonization.