Periodontitis is an infectious disease, resulting in inflammation within the supporting tissues of the teeth which lead to periodontal pocket deepening, loss of attachment and bone. Intrabony defects are those with apical location of base of the pocket relative to bone crest.Demineralized freeze‐dried bone allograft (DFDBA) is an allograft that harbor’s a variety of growth/differentiation factors, notably bone morphogenetic proteins (BMPs) 2, 4, and 7.Single-flap approach (SFA) is one of the periodontal flap designs proposed to minimize the surgical trauma.LLLT is based on the biostimulation effect, which is based on the fact that cellular behavior can be changed by irradiation at a particular wavelength. Both SFA and LLLT have beneficial effects on probing pocket depth reduction, periodontal wound healing, and obtaining clinical attachment.All the recruited patients will be receiving phase I therapy which includes scaling and root planing which will be performed by single operator. Oral hygiene instructions will be given. Two weeks after SRP all clinical and radiological parameters will be recorded.A buccal envelope flap will be made using Sulcular incisions in the surgical area following the gingival margin of the teeth.Upon completion of the root instrumentation, defect depth, defect width, and wall present will be measured. Control group will receive only DFDBA biomaterial after surgical debridement. In the test group LLLT (Diode laser, Woodpecker) irradiation with 976‐nm wave length at 1.5 W, continuous wave for 5s before surgical debridement will be done and DFDBA biomaterial will be placed.At wound closure vertical internal mattress suture will be placed.Sutures will be removed after two weeks and EHI wound healing index will be recorded. The surgical site will be evaluated on the basis of the clinical parameters will be recorded after 3- and 6-months and radiographic parameters will be recorded after 6 months.