Periodontitis is a multifactorial disease, in which a complex microbial ecology that matures in biofilms in the subgingival sulcus triggers a chronic immunoinflammatory lesion that leads to loss of clinical attachment due to the destruction of the periodontal ligament and adjacent supporting bone. 

Diabetes mellitus is a chronic metabolic disease characterized by hyperglycaemia. It results from insulin resistance, insulin deficiency, or a total lack of insulin. It has four subgroups: type 1 DM (insulin-dependent diabetes), type 2 DM (non-insulin-dependent diabetes), gestational DM, and other specific types. Among DM patients, 90–95% have type 2 diabetes. DM and periodontal disease have a bidirectional relationship. DM can increase the prevalence, incidence, and severity of periodontal diseases. Likewise, periodontal diseases can complicate the metabolic control of DM. 

Inhibiting progression of inflammation by mechanical debridement of plaque and calculus harbouring the disease progression is the mainstay of management of periodontitis. The purpose of scaling and root planning (SRP) is to remove such local irritants from the teeth surface and to minimize tooth surface roughness which may facilitate the accumulation of local irritants around the teeth. Mechanical therapy alone may not always be predictable or fully eliminate periodontal infection and inflammation. It can fail to remove pathogenic bacteria located deep within the periodontal tissues or in inaccessible areas. This is especially true for systemically compromised patients and individuals with severe periodontitis, such as diabetic patients. 

Adjunctive periodontal therapies, such as the use of antimicrobial agents, antimicrobial photodynamic therapy, and lasers of various wavelengths, are often recommended to enhance the outcomes of mechanical treatment. These additional therapies have shown positive clinical impact in the management of periodontitis. The use of laser applications has been raised as an alternative to supportive treatments to increase the efficacy of nonsurgical periodontal treatments and decrease the limitations. 

Researches related to photo biomodulation therapy (PBMT) are conducted at the level of in vitro or animal studies. Photo biomodulation (PBM), formerly known as low-level laser therapy (LLLT), is a therapeutic treatment that uses optimal doses of laser photonic energy in the red and near infrared wavelengths. These wavelengths are part of the electromagnetic spectrum’s "optical therapeutic window." Evidence has proven that PBM therapy (PBMT) stimulates gingival fibroblast proliferation and improves its organization. 

Administration of PBMT has a positive effect on cell proliferation in gingival fibroblasts, resulting in increased expression of FGF-b. In another study by Hakkı et al., laser photo biomodulation was found to significantly increase the expression of type-1 collagen mRNA. PBMT has drawn significant attention for its biostimulative effect on tissue healing. Cellular and animal studies have reported that it increases fibroblast and osteoblast activation, contributing to tissue healing. This effect is noteworthy not only in healthy individuals but also in patients with systemic diseases such as DM.When used as an adjunct to periodontal therapy, PBMT may potentiate the effects of SRP by reducing bacterial load, altering inflammatory response and accelerating healing. However, in patients with uncontrolled type 2 DM, where periodontal disease progresses more severely, there are limited studies on the additional benefits of PBMT. 

Considering the above facts, the aim of the current study is to investigate and evaluate the periodontal status of type-II diabetes mellitus patients with periodontitis after scaling and root planning with and without PBMT (photo biomodulation therapy)