Multicenter Clinical Study on the Efficacy and Esthetic Outcomes of Immediate Implant Placement Using the Socket-Shield Technique Versus Conventional Immediate Implantation in the Anterior Maxillary Esthetic Zone

This is a prospective, multicenter, parallel-group, evaluator-blinded randomized controlled trial.It aims to compare the Socket Shield Technique (SST) with conventional immediate implant placement (IIP) in the maxillary anterior aesthetic zone, evaluating labial bone plate thickness, implant survival/success rates, pink aesthetics, and patient satisfaction to assess their clinical efficacy and aesthetic outcomes.

Eligible participants will provide informed consent and be randomly assigned to groups via center-stratified randomization.

Primary endpoint: Changes in buccal bone plate thickness at the implant shoulder and at 2, 4, and 6 mm apically at 6 months after prosthetic restoration (T3).

Secondary endpoints: Implant survival and success rates; changes in buccal bone volume; changes in soft tissue contour convexity; Pink Esthetic Score (PES); patient satisfaction; operative time, pain levels, and treatment-related parameters.

Safety endpoints: Intraoperative and postoperative adverse events, including infection, bleeding, wound dehiscence, implant loosening, peri-implantitis, shield fragment displacement/exposure/dislodgement, need for reoperation, and other serious adverse events (SAEs).

• the Socket Shield Technique (SST) immediate implant placement (Procedure), also known as Group SST: During tooth extraction, a stable buccal root fragment (shield) is preserved. The specific procedures are as follows: Minimally invasively extract the crown of the affected tooth, preserving a buccal root fragment approximately 1-2 mm in thickness; Adjust the coronal aspect of the root fragment to approximately 2 mm apical to the gingival margin, ensuring a rounded and blunt coronal edge that is flush with the alveolar crest; Maintain the integrity of the buccal bone plate without any fractures;
• Conventional immediate implant placement (Procedure), also known as Group IIP: Completely remove the root of the affected tooth and complete the procedure according to the conventional immediate implant placement protocol: Minimally invasively extract the affected tooth (complete root extraction); Place the implant within the extraction socket (biased toward the palatal side); Fill the jump gap with a low-resorption xenogeneic bone substitute material; Perform soft and hard tissue management according to the conventional immediate implant placement SOP.

Primary outcomes

• Thickness of the labial bone plate [6 months after the restoration (T3)]: The changes in the thickness of the labial bone plate at the implant shoulder and 2, 4, and 6 mm below

Secondary outcomes

• Implant retention and success rate [3, 6,12 ,24 and 36 months after the operaiton]
• Volume change of the labial bone plate [6 months after the crown restoration was completed]
• Change in the contour curvature of soft tissues [6 months after the crown restoration was completed]
• Pink Aesthetic Score (PES) [6 months after the crown restoration was completed]
• Patients' satisfaction degree [On the day after the surgery, the day of crown restoration completion, and 6 months after the restoration was completed]

Sex: All, ages: 18 Years to 65 Years

Inclusion Criteria:

* Age: 18 to 65 years old;

  * Good general health, able to tolerate oral implant surgery, with no absolute surgical contraindications (ASA I or II);

    * Clinical diagnosis of an unrestorable maxillary anterior tooth, suitable for immediate implant placement; ④ Periodontal tissues are basically healthy, with no obvious active infection in the apical area; ⑤ No obvious root fracture on the labial/buccal side or severe mobility preoperatively; radiographic evaluation confirms that the bone volume in the surgical site meets the requirements of the protocol; ⑥ Willing to accept randomization and standardized follow-up, and has signed the Informed Consent Form; ⑦ Able to provide complete intraoral photographs, CBCT (Cone Beam Computed Tomography) scans, and follow-up data.

Exclusion Criteria:

* Presence of severe systemic diseases that may affect the surgery or healing, or current use of related medications such as bisphosphonates;

  * Severe periodontal disease or uncontrolled poor oral hygiene;

    * Obvious inflammation in the apical area of the affected tooth, or pathological root resorption; ④ Abnormal occlusal relationship, obvious bruxism, or inability to establish a stable restorative occlusion;

      * Pregnancy or lactation, or unsuitability for radiographic examination; ⑥ History of previous surgery or radiotherapy affecting the bone volume or soft tissues in the target area, which the investigator deems would seriously interfere with the evaluation; ⑦ Expected inability to complete the follow-up, or refusal to comply with the study requirements.