Periodontitis is a chronic inflammatory disease of the periodontium with the primary etiologic factor comprising of a subset of specific bacteria of the oral microbial flora.¹   The presence of bacterial plaque thus plays an important role in etiology, initiation and progression of inflammatory periodontal diseases. The provocative host response in addition to its defensive action may occasionally lead to progressive destruction of the supporting periodontal structures.²

With the primary goal of elimination of the infection and prevention of disease progression,  etiologic plaque elimination & root surface debridement by scaling and root planing came into existence in the first half of the past century and since has become the fundamental feature held in common by all currently used forms of periodontal therapy.² In search of a more efficient and atraumatic technique which improves periodontal healing, the use of local drug delivery and lasers for periodontal treatment have been proposed.³

Systemic antimicrobial agents have routinely been employed as an adjunct to mechanical periodontal therapy.⁴ Systemic administrations has been useful in treating periodontal pockets, but repeated, long-term use of systemic antibiotics is fraught with potential danger including resistant strains and superimposed infections.⁵   To overcome the shortcomings of systemic antimicrobials, various local drug delivery systems with chemotherapeutic agents were proposed.⁴

The concept of sustained local drug delivery was first developed by Dr. Max Goodson in (1979).^[7] Chemical antimicrobial agents may gain direct access into the periodontal pocket thus offering them superiority over systemically administered ones. The scientific rationale behind the use of local drug delivery of antimicrobial agents in periodontal pockets is to eliminate or inhibit subgingival bacteria by using the antimicrobial agents at the site i.e. in pockets, with no or minimal systemic side effects. Various antibiotics and antimicrobial agents have been recognised as local drug delivery agents viz. Chlorhexidine, Tetracycline, Minocycline, Metronidazole etc., available in various delivery systems in the form of gels, chips, fibres etc. The primary objective was to confer therapeutic concentrations of an antimicrobial substance for a prolonged duration.

Metronidazole (MTZ) is a well-known antibiotic which is effective against various types of species including gram-negative rods and spirochetes.⁶ The use of Metronidazole antimicrobial therapy for treating gingivitis has persuaded interest in clinicians as the therapy is site specific, with reduced side effects and can be applied topically with better compliance and reduced systemic consequences.⁷ Along with other numerous antimicrobial therapeutic agents, Chlorhexidine (CHX) still remains ideal chemical with reasonable antiplaque efficacy and is considered one of the most effective mouth rinses used for successfully treating plaque related gingivitis.⁸ Both the agents have been widely used for treating gingivitis however perusal of literature showed lack of studies comparing effects of different concentration combinations on gingivitis.

The first sustained release dosage form of Chlorhexidine diacetate for local use was developed in 1982 by Friedman & Golumb.⁹ The release rate of Chlorhexidine was measured using an ultraviolet spectrophotometer. The release of Chlorhexidine from this device were shown to be dependent on the degree of protein cross linking. When the Chlorhexidine incorporated chip is placed subgingivally 40% of Chlorhexidine is released in 24 hours and the remainder in 7-10 days. The mean concentration of Chlorhexidine in the gingival crevicular fluid was 1000 mg/ml at four hours and 480 mg /ml within 24 hours. Hence, the therapeutic concentration of Chlorhexidine as an antimicrobial substance is enough to kill microbes which reside in the periodontal pocket.¹⁰ Both the agents have been widely used for treating gingivitis however perusal of literature showed lack of studies comparing effects of different concentration combinations on gingivitis. Metronidazole 1.5% and Chlorhexidine 0.5% gel applied on day 0 and the effects will be measured at one week and one month interval (Metrohex® Plus Gel, Dr Reddy’s Laboratories Ltd, H.P. India).

Achyranthes aspera is an important herbal remedy used most commonly in allied medicine¹¹, as it has various pharmacological properties such as antimicrobial, analgesic, antipyretic, anti-inflammatory, immune-stimulant, antioxidant, properties¹². The parts of the plants which are commonly used in dentistry in order to maintain oral health are stem and root. Due to the major role of the plant as an antimicrobial agent, it is commonly used for oral hygiene maintenance. In certain parts of India, the plant is used for relieving pain in case of toothache. It also contributes in management of halitosis, teeth whitening and maintenance of strong and healthy gums.

Due to the anti-cariogenic potential of this plant it is widely used as a tooth cleaning aid in India since ages. There are many ways of using it for maintenance of oral hygiene. It can be used in the form of dentifrice, mouthwash or a local drug delivery system. In order to obtain the maximum benefits of the plant extract the concentration should be higher than the MIC (Minimum Inhibitory Concentration) of the drug. MIC is termed as the least concentration of the required to produce inhibition of bacterial growth with an absorbance level lesser than 0.05–550 nm (no evident growth). Keeping this thing into consideration, new products are formulated with appropriate concentration in order to provide maximum benefit.¹³

Achyranthes aspera due to its anti-microbial action can be used for prevention and maintenance of Chronic periodontitis. Ramnarayana Boyapati studied the role of Achyranthes aspera in treatment of periodontal diseases, when it is delivered subgingivally as a locally administered agent along with SRP due to its favourable effect in the form of anti-microbial activity. Three properties of the plant which helps in improving the clinical and the microbiological aspects included antimicrobial, anti-inflammatory and antioxidant activity.¹⁴ The antibacterial action of the plant is due to the presence of alkanoids and tannins which are among the main phytochemical agents present in the plant. The root extract which is derived from petroleum ether has a strong antimicrobial activity for the gram positive bacteria whereas the methanol and chloroform extract of the plant are used for their antimicrobial activity towards gram negative bacteria. The difference in the anti-microbial activity is due to the difference in composition of cell wall and cell membrane among different bacteria¹⁵. The radical scavenging activity of the plant towards the free radical formation occurring during the periodontal disease activity was due to the presence of phenolic compounds in the plant extract which was very evident in the studies conducted in the past. The two main radicals targeted by these phenolic compounds were namely 2,2 diphenyl-1-picrylhydrazyl and superoxide which are the main culprits responsible for the destruction of periodontal tissues during the disease process¹⁶.

Achyranthes aspera in its gel form was used a local drug therapy for the protection of periodontal tissues from the pathogens as it is very effective in management of inflammation in tissues¹⁷. An animal study was conducted by Kumar et al¹⁸ in which the alcoholic extract of the plants was used, the plant extract exhibited stimulation of immune system via the proliferation of T-lymphocytes¹⁹. The regeneration potential of the plant extract is also helpful in many ways. Due to the phenolic component present in the plant extract it is highly effective in regeneration of the lost tissues so it contributes majorly in the dealing with wounds²⁰. The phenolic compounds lead to formation of a film around the exposed wound tissue causing prevention of loss of fluid from the tissues as well as formation of a chemical barrier²¹. The film also acts as a physical barrier by providing insulation to the wound area. This property of the plant helps in better healing of the treated sites.

The role of dental plaque in initiation and progression of the periodontal disease is evident. One of the most prevalent periodontal pathogens is Porphyromonas gingivalis, which is responsible for evasion of host immune response. P. gingivalis is a gram negative facultative anaerobe which has high predominance among the many oral pathogens²². Keeping this thing into consideration, P. gingivalis has been included as one of the parameters in the study.

Literature is replete with various studies incorporating different treatment modalities individually. The present study aims to compare and evaluate the clinical and antimicrobial efficacy of subgingivally delivered of local drug delivery agents namely Achyranthes aspera gel and Metronidazole-Chlorhexidine combination gel as an adjunct to scaling and root planing against Porphyromonas gingivalis levels in periodontitis patients for the treatment of  Periodontitis.