Periodontitis is an infection of the ligament and bone supporting the tooth and is caused by the presence of periodontopathogenic species in a susceptible host, affecting 5% to 20% of the adult population in a clinically significant manner. Periodontal therapy is based on supra- and sub-gingival disinfection concomitant with the establishment of an environment that is less favorable for periodontopathogenic growth. Though the adequacy of mechanical debridement (scaling and root planing) in the treatment of periodontitis has been well acknowledged. Chemo-mechanical concept has been developed where in a chemical agent is used as an adjunct to scaling and root planing to improve the outcome of scaling and root planing and furthermore prevent early microbial re-colonization to ultimately ensure the best chance to clinical improvement. Therefore a research project was undertaken to evaluate the efficacy of Chlorhexidine – Thymol varnish (chemical) as an adjunct to scaling and root planing (mechanical) and compare it's results with mechanical debridement alone in the eradication of microbial colonies and improvement of periodontal parameters, which is discussed in depth in this book.