Abstract : Immediate implant placement in mandibular molars remains surgically challenging because of wide extraction sockets, possible residual infection, and early soft-tissue instability. Optimizing postoperative healing and minimizing inflammation are essential for long-term implant success. Active oxygen–based oral gels such as Blue®m possess antimicrobial and tissue-regenerative properties; however, their clinical effect following immediate molar implant placement has not been fully established. This study evaluated the clinical effect of active oxygen–based gel on healing after immediate implant placement in mandibular molars using custom-made healing abutments, with emphasis on pain, peri-implant inflammation, wound healing, implant stability, and marginal bone changes. A randomized controlled clinical trial was conducted on 24 patients requiring immediate implant placement in mandibular molar sites. Patients were randomly allocated into: -study Group (n=12): application of Blue®m Gel immediately after implant placement. -Control Group (n=12): immediate implant placement without gel application. All implants were placed using a standardized surgical protocol with custom-made healing abutments to preserve peri-implant soft tissue architecture. Postoperative assessment included pain using the Visual Analog Scale (VAS), inflammatory response, soft-tissue healing, implant stability quotient (ISQ), and radiographic marginal bone loss. Data were analyzed using descriptive and comparative statistics. The test group demonstrated significantly lower postoperative pain and inflammatory scores during the early healing period. Faster epithelialization and improved soft-tissue closure were observed in the gel group during the first two postoperative weeks. Mean ISQ values were slightly higher in the test group, although the difference was not statistically significant. Lower early marginal bone loss was also observed at 6 months. Application of active oxygen–based Blue®m Gel following immediate implant placement in mandibular molars enhanced early postoperative healing by reducing pain and inflammation, accelerating soft-tissue healing, and improving peri-implant tissue stability.