The rate of periodontal health among adults and the elderly in China is less than 10%, with the prevalence of severe periodontitis reaching 30.6% in those aged 35 and above. While conventional periodontal treatment (ultrasonic combined with manual subgingival scaling) is effective, it has significant drawbacks: it is technically demanding, time-consuming, and often causes patients considerable pain and discomfort. This can lead to poor treatment compliance, postoperative tissue damage, bleeding, and root sensitivity.Lasers, such as the Nd:YAG laser, offer advantages like antibacterial effects and minimally invasive debridement. Combining ultrasonic with laser therapy may improve patient comfort, but there is currently insufficient evidence to prove that its clinical efficacy is non-inferior to traditional manual scaling.This study aims to compare the clinical efficacy, patient acceptance, and postoperative recovery between "ultrasonic combined with laser debridement" and "ultrasonic combined with manual mechanical debridement."

The periodontal health rate in the adult and elderly groups in China is less than 10%, with a prevalence of severe periodontitis as high as 30.6% among adults aged 35 and above. The primary treatment goal of periodontitis is to control infection by removing dental plaque and calculus, preventing disease progression. Therefore, periodontal debridement is the most fundamental treatment required for every periodontitis patient. Although ultrasonic combined with manual subgingival scaling demonstrates good clinical efficacy in periodontitis treatment, it also has some significant drawbacks. First, the use of manual instruments requires higher technical skills and is time-consuming, especially when dealing with complex root surfaces. Second, the manual scaling process is relatively uncomfortable, and severe pain may prompt some patients to require analgesics or even refuse treatment, particularly in cases of moderate to severe periodontitis. Factors such as past dental anxiety can amplify this pain response, affecting treatment compliance. Additionally, manual scaling may cause damage to periodontal tissues in the treatment area, especially when operating in the subgingival region, where significant mechanical trauma can lead to postoperative discomfort, pain, and root surface sensitivity. This trauma not only affects the patient's treatment experience but may also reduce the regenerative capacity of gingival tissues after treatment. Moreover, postoperative bleeding and root surface roughness following manual scaling increase the risk of infection and complications. Conventional periodontal basic treatment typically involves ultrasonic combined with manual mechanical debridement, but due to the aforementioned issues, many patients have limited acceptance of manual subgingival scaling. This fear or resistance affects treatment compliance, ultimately impacting the prognosis of periodontitis patients. The technical difficulty of manual subgingival scaling also limits the promotion and application of this periodontal debridement technique. Therefore, there is an urgent need for an alternative technology that can effectively treat periodontitis while improving patient comfort and being easily mastered by clinicians. In recent years, lasers have gained widespread attention due to their localized antibacterial and hemostatic effects, as well as their ability to reduce inflammatory reactions. Nd:YAG lasers, a type of near-infrared laser, excel in sterilization, hemostasis, and tissue ablation, and have become an auxiliary treatment for periodontal disease. The minimally invasive debridement technique combining ultrasonic and laser has shown promising potential in treating periodontitis, particularly in enhancing patient comfort and reducing postoperative discomfort. However, there is still insufficient evidence to prove its non-inferiority in clinical efficacy compared to traditional ultrasonic combined with manual scaling. This study aims to compare the clinical efficacy, patient acceptance, and postoperative recovery between ultrasonic combined with laser debridement and ultrasonic combined with manual mechanical debridement through a muti-center randomized controlled trial, thereby providing a more scientific basis for periodontal disease treatment.This study was conducted in multiple centers using a stratified design, covering three provincial-level tertiary hospitals and three primary hospitals. The study adopts a split design (self controlled left and right sides) and plans to include at least 174 patients.

Inclusion Criteria:

• Age ≥ 18 years old
• Diagnosed with stage III-IV periodontitis, with at least 4 affected teeth on each side (left and right) having probing depth ≥ 5 mm
• No periodontal basic treatment (e.g., scaling, root planing, flap surgery) performed within the past 6 months
• Able to understand the study procedures, provide informed consent, and comply with protocol requirements
• At least 10 remaining teeth on either side of one jaw (maxilla or mandible)

Exclusion Criteria:

• Unstable or uncontrolled systemic diseases, including but not limited to progressive liver disease, active infectious disease, severe trauma, renal failure, rheumatoid arthritis, hematological disease, mental disorder, or diabetes mellitus
• Presence of an implanted pacemaker
• Pregnancy or lactation
• Malignant tumors, or undergoing radiotherapy, chemotherapy, targeted therapy, or bisphosphonate treatment
• Undergoing orthodontic treatment or those who have received orthodontic treatment within the past six months
• Smokers