This article presents a case report of the use of a perioscope in the treatment of deep periodontal pockets at teeth with permanent prosthetic restorations. A perioscope uses endoscopic technology to visualize the subgingival environment and locate calculus deposits. It enables imaging of the examined structure providing 24-48 times magnification on the monitor in real time. The optical fiber is inserted into the periodontal pocket with a constant supply of water, which ensures good visibility. The image is then transmitted to a monitor, allowing immediate visualization of the tooth root surface. In addition to its use in periodontology, the perioscope can be utilized to diagnose root cracks, defects located below the gum margin and to assess the marginal fit of permanent prosthetic works. This type of endoscopic examination may eliminate unnecessary exposure to X-ray radiation. In the presented case, the use of a perioscope enabled the visualization and removal of deposits located near the margin of the permanent prosthetic restoration. Surgical procedures such as open flap debridement provide direct visualization and better debridement opportunity, but may lead to root exposure, discomfort and longer healing, and in patients with systemic disease, there may be contraindications to this type of procedures. Therefore, it is important to develop non-surgical methods of subgingival debridement, such as endoscopy-assisted treatment.