Effect of Photodynamic therapy as an adjunct to surgical management of Chronic Periodontitis

Chronic periodontitis is an infectious disease resulting ininflammation within the supporting tissues of the teeth, loss of progressiveattachment and bone loss and is characterized by pocket formation and/orgingival recession. Scaling and root planning (SRP) is the most commonperiodontal treatment which has proven clinical effectiveness in terms ofdecreasing the probing pocket depth, reducing inflammation and improving theclinical attachment level (CAL).SRP has some limitations, such as difficultiesin accessing deeper pockets, root concavities and furcation areas. Hence tofacilitate SRP, flap surgery is recommended to gain better access, Periodontal flap surgery is an open  flap debridement procedure, which eliminatesthe periodontal pocket depth with a potential to remove the bacterial biofilmand endotoxins from root surfaces of the teeth and to prevent further clinicalattachment loss.Although elimination of granulation tissue reducesbacterial pathogen, it still remains a fact that it fails to eradicate theperiopathogens. The success of such treatment depends on complete removalof  granulation tissue, adequate oralhygiene maintenance and success to comply with supportive periodontal therapy.Hence development of alternative antibacterial therapeutic strategies hasbecome important in evolution of modalities to control microbial growth in oralcavity.

Recently an application of light energy with laser, alsoknown as phototherapy to decontaminate the pockets environment, has beenexplored. Anti-microbial photodynamic therapy also known as photoactivateddisinfection (PAD), involves the use of selective photosensitizer which isactivated by a light source of a wavelength corresponding to the absorptionmaximum of the photosensitizer. The activated photosensitizer reaches thedeeper tissues to bind to the bacterial cell wall and in some instances,penetrates into the cytoplasm.

Indocyanine green (ICG), a water soluble tricarbocyaninedye, has proven to be a photosensitizer which has an optimal peak absorption at800-810nm range of wavelengths. This range has a penetration depth of 6-6.5mm,which exceeds the thickness of the mucous membrane, both in normal andpathological state, ICG has been effective in eradicating the organisms suchas: Staphylococcus Aureus, Pseudomonas Aeruginosa, Porphyromonas gingivalis andAggregatibacter Actinomycetemcomitans, thereby reducing their concentrationsand ultimately improving periodontal status.

The present study aimed to evaluate the clinical andmicrobial effect of open flap debridement with and without photodynamictherapy.

STUDY PROCEDURE

The present study is a split mouth design. A total of 10 patients with chronic periodontitis will be selected into the study. The contralateral quadrants will be randomly divided into two groups according to the inclusion and exclusion criteria.

Group A-Open flap debridement in combination with photodynamic therapy(OFD+PDT) (n=10 sites).

Group B-Open flap debridement alone(OFD) (n=10 sites).

At the initial visit, clinical examination will be performed on each patient and clinical parameters will be recorded such as Plaque index(PI),Gingival index(GI),Probing pocket depth(PPD) and Clinical attachment level(CAL).

All patients will receive phase I therapy which includes scaling and thorough oral hygiene instructions. One week after scaling, baseline subgingival plaque samples will be collected using sterile curette placed into the deepest periodontal pocket for 45sec, the collected sample will be transferred to a transport medium (Tris EDTA Buffer medium) and will be sent to laboratory for microbiological analysis of Porphyromonas gingivalis(Pg),Aggregatibacter actinomycetomcomitans(Aa), Prevotella intermedia(Pi).

SURGICAL PROCEDURE

All patients will be treated using the following surgical protocol. Pre-operative rinse with 0.2% chlorhexidine for 60sec and local administration of 2% lignocaine with adrenaline at a concentration of 1:80000.

After local anesthesia, a crevicular incision will be given using a No.15 surgical blade.

A full thickness mucoperiosteal flap is raised, using a periosteal elevator.

Following this, a thorough debridement of the root surfaces will be performed.

**In Group A-**After complete debridement, each test site will be rinsed with ICG dye using a blunt side release cannula. Sterile saline will be used to remove the excess dye from the site. After thorough rinsing the light source with 810nm wavelength diode laser will be carried out for 40sec, then flap will be closed with interrupted sutures using 3-0 braided silk suture material.

In **Group B-**After thorough debridement of root surfaces, flap will be closed with interrupted sutures using 3-0 braided silk suture material.

Post-operative care

The patient will be instructed not to disturb the surgical site until the sutures are removed. Antibiotics and analgesics will be prescribed.  After two weeks, the sutures will be removed and the oral hygiene instructions will be emphasized. Clinical parameters will be recorded 3 months after treatment, post operative subgingival plaque samples will be collected from both groups using sterile curette and then transferred into vial with transporting medium (Tris EDTA Buffer medium), which is then labelled with an appropriate code in correspondence with the operator. The labelled vials will be transported for Real Time polymerized chain reaction for microbiological analysis.