Abstract
Adjunctive antimicrobials can enhance non-surgical periodontal therapy by suppressing residual pathogens within deep periodontal pockets. This article presents a reproducible, chairside protocol for delivering a biodegradable 14% doxycycline gel as an adjunct to scaling and root planing (SRP) in adults with stage III or IV periodontitis. The workflow includes participant screening and informed consent, randomization to three arms (SRP plus doxycycline gel; SRP plus placebo gel; SRP alone), allocation concealment, standardized full-mouth debridement, and blinded gel delivery using a blunt cannula with a base-to-margin filling approach. Postoperative instructions and scheduled follow-ups at 1, 3, and 6 months are described to support consistency across operators and visits. Clinical outcomes include probing pocket depth (PPD), clinical attachment level (CAL), gingival index (GI), and bleeding on probing (BOP). Site-specific microbiological sampling targets red-complex organisms (Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola) using sterile paper points followed by quantitative laboratory analysis with pre-defined quality controls. Examiner calibration, instrument sterility checks, and protocol stopping points are specified to strengthen fidelity and safety. Representative results show that adjunctive doxycycline gel is most likely to yield incremental benefit at deeper residual sites, with between-group differences at full-mouth averages expected to be smaller, consistent with prior evidence on locally delivered antimicrobials after meticulous SRP11-13. This protocol is designed to be video-capturable and readily implemented in clinical research and advanced periodontal training.