Alveolar Ridge Preservation Using Bone Allografts With a PRF Membrane Versus GBR: A Randomized Controlled Clinical Trial.

Study Design

• Study Type: Interventional (Clinical Trial)
• Study Design: Prospective randomized controlled trial
• Estimated Enrollment: 51 participants
• Allocation: Randomized
• Intervention Model: Parallel Assignment
• Masking: Single-blinded (Outcome Assessor)
• Primary Purpose: Treatment

Study Procedures

All study procedures will be performed according to a strictly standardized protocol and in a predefined chronological sequence to ensure the reliability and reproducibility of all measurements.

1. Preoperative Phase 1.1 Participant Eligibility Assessment

   Clinical and Radiographic Examination

   • Recording of complete medical and dental history.
   • Comprehensive clinical examination and verification of the inclusion and exclusion criteria.

   Informed Consent

   Eligible participants will provide written informed consent before enrollment.

   Randomization

   Participants will be randomly allocated to one of the three treatment groups using a computer-generated randomization sequence.

   Visit 1 (Baseline - Day of Tooth Extraction)

   The following baseline measurements will be recorded:

   • Width of keratinized tissue (using a UNC-15 periodontal probe; Hu-Friedy Group Coded #UNC CP-15).
   • Gingival/mucosal thickness measured using an ultrasonic soft tissue device (Pirop®, Echoson, Krancowa, Poland).
   • Standardized intraoral photographs of the site

   1.2 Surgical Procedure

   All surgical procedures will be performed under local anesthesia.

   An atraumatic tooth extraction will be carried out using periotomes and elevators while avoiding flap elevation whenever possible.

   Following extraction:

   • Thorough debridement and curettage of the extraction socket.
   • Verification of the integrity of all socket bony walls.

   Group A - Spontaneous Healing

   • No grafting material or barrier membrane will be placed.
   • Stabilization of the blood clot using resorbable sutures (PGA 5-0). A figure-of-eight suture to create an H-shaped configuration over the membrane.

   Group B - Allograft + Guided Bone Regeneration (GBR) Membrane

   • Placement of particulate bone allograft up to the level of the alveolar crest (Corticocancellous Granules (0.25-1.0 mm), ALO580, 0.5 cc, Manufacturer: Cells + Tissuebank Austria CTBA, Magnesitstraße 1, 3500 Krems an der Donau, Austria)
   • Placement of Resorbable Synthetic bilayer Barrier Membrane composed of poly(lactic-co-glycolic acid) (PLGA) (Septodont RTR+ Membrane®).

   The membrane stabilises the soft tissues of the socket allowing healing by an open mode.

   * Suturing of the soft tissues with a resorbable 5-0 polyglycolic acid (PGA) suture (Medipac, Greece), using a figure-of-eight suture to create an H-shaped configuration over the PLGA membrane.

   Group C - Allograft + Platelet-Rich Fibrin (PRF) Membrane

   • Collection of approximately 10 mL of venous blood before tooth extraction.
   • Immediate centrifugation according to a standardized protocol.
   • Preparation of the PRF membrane.
   • Placement of particulate bone allograft as above (ALO580-CTBA) into the extraction socket and enrichment with injectable PRF (i-PRF).
   • Placement of the PRF membrane over the socket entrance in a manner similar to the GBR membrane.
   • Suturing of the soft tissues with a resorbable 5-0 polyglycolic acid (PGA) suture (Medipac, Greece), using a figure-of-eight suture to create an H-shaped configuration over the PRF membrane.

   1.3 Radiographic Examination

   The following radiographic examinations will be performed:

   • Standardized periapical radiograph using the paralleling technique with a customized radiographic positioning guide.
   • Cone Beam Computed Tomography (CBCT) for three-dimensional evaluation of the alveolar ridge dimensions using a customized reference stent.

   Time points: day of the extraction and 3 months post-operatively.

   Baseline radiographic examinations (performed immediately after tooth extraction) will be obtained exclusively for research purposes.

   CBCT scans will be acquired on the day of extraction and at 3 months postoperatively, with the reference stent positioned identically at both time points.

   A field of view (FOV) of 6 × 6 cm will be selected using high-resolution settings (voxel size: 150 μm, scan time: 9 seconds, tube voltage: 110 kV). All radiographic examinations will be performed using low-dose radiation according to the ALARA (As Low As Reasonably Achievable) principle. When necessary, an artifact reduction algorithm will be applied to improve image quality.

   1.4 Postoperative Instructions

   Participants will receive standardized postoperative instructions including:

   * Oral hygiene instructions with avoidance of mechanical cleaning at the surgical site.

   • No routine postoperative antibiotic prescription.
   • Use of 0.12% chlorhexidine mouth rinse for 2 weeks.
   • Analgesics as needed (ibuprofen 400 mg or paracetamol 500 mg).
   • Recording of any postoperative complications.
   • Distribution of a Visual Analog Scale (VAS) questionnaire for postoperative pain assessment.

   Visit 2 (7 Days Postoperatively)

   * Clinical evaluation of wound healing (visual clinical assessment).

   • Collection of the completed VAS questionnaire.
   • Assessment of healing and documentation of adverse events (inflammation, wound dehiscence, or graft/membrane exfoliation).
   • Standardized intraoral photographs.
   • Oral hygiene instructions.

   Visit 3 (14 Days Postoperatively)

   * Clinical evaluation of wound healing (visual clinical assessment).

   • Assessment of healing and documentation of adverse events (inflammation, wound dehiscence, or graft/membrane exfoliation).
   • Standardized intraoral photographs.
   • Suture removal.
   • Oral hygiene instructions

   Visit 4 (6 Weeks Postoperatively)

   * Clinical evaluation of wound healing (visual clinical assessment).

   * Assessment of healing and documentation of adverse events (inflammation, wound dehiscence, or graft/membrane exfoliation).

   * Standardized intraoral photographs.

   * Oral hygiene instructions

   Visit 5 (3 Months Postoperatively)

   5.1 Clinical Measurements

   * Width of keratinized tissue (using a UNC-15 periodontal probe; Hu-Friedy Group Coded #UNC CP-15).

   * Gingival/mucosal thickness measured using an ultrasonic soft tissue device (Pirop®, Echoson, Krancowa, Poland).

   * Standardized intraoral photographs.

   5.2 Radiographic Measurements

   * Standardized periapical radiograph.

   * CBCT scan.

   Measurements will include:

   • Horizontal alveolar ridge width.
   • Vertical alveolar ridge height changes.

   Radiographic measurements will be performed by a blinded examiner using dedicated image-analysis software.

5. Definition of Variables and Outcome Measures

This randomized clinical trial will record demographic, clinical, and radiographic variables. Variables will be classified as independent (intervention), dependent (outcomes), and potential confounding variables.

1. Independent Variable

Type of Therapeutic Intervention

Nominal categorical variable.

Treatment groups:

1. Spontaneous healing (Group A)
2. Bone allograft + GBR membrane (Group B)
3. Bone allograft + PRF membrane (Group C)

Allocation method:

Computer-generated randomization sequence.

2. Demographic Variables

Age

• Continuous variable.
• Unit: years.
• Recorded from the medical history.

Sex

* Nominal categorical variable.

* Categories: Male / Female.

Smoking Status

• Categorical variable.
• Categories:
• Non-smoker
• Light smoker (≤10 cigarettes/day)

• Recorded from the medical history.

  3. Primary Outcome

Changes in Alveolar Ridge Dimensions

1. Horizontal Ridge Width

   • Continuous variable.
   • Unit: millimeters (mm).
   • Measured on CBCT images.
   • Time points:
   • Baseline (T0)
   • Three months (T2)
   • Outcome calculated as:
   • T2 - T0.

2. Vertical Ridge Height

   • Continuous variable.
   • Unit: millimeters (mm).
   • Measured on CBCT and standardized periapical radiographs.
   • Change calculated between T0 and T2.

   Measurement Tools

   * Digital CBCT image-analysis software.

   * Customized radiographic positioning guide to ensure reproducibility.

   4. Secondary Outcomes

   4.1 Gingival/Mucosal Thickness

   • Continuous variable.
   • Unit: millimeters.
   • Measured using an ultrasonic soft tissue measuring device.
   • Recorded at baseline and at 3 months.

   4.2 Width of Keratinized Tissue

   * Continuous variable.

   • Unit: millimeters.
   • Measured using a UNC-15 periodontal probe.
   • Measured from the free gingival margin to the mucogingival junction.
   • Recorded at baseline and at 3 months.

   4.3 Early Wound Healing

   * Visual wound-healing assessment.

   • Buccolingual and mesiodistal wound dimensions (mm) will be recorded.
   • Recorded immediately after extraction (baseline) and at 14 days.
   • Clinical evaluation performed by a blinded examiner.

   4.4 Changes in Clinical Attachment Level of Adjacent Teeth (Gingival Recession)

   *Continuous variable.

   • Unit: millimeters.
   • Measured using a UNC-15 periodontal probe.

   • Distance measured from the cementoenamel junction (CEJ) to the free gingival margin.

     • 5. Surgical/Procedural Variables

   Surgical Time

   * Continuous variable.

   * Unit: minutes.

   * Measured using a stopwatch.

   Postoperative Complications

   * Categorical variable.

   • Categories: Yes / No.

   • Type of complication will be documented.

     6. Measurement Reliability

   • All measurements will be performed by a single calibrated examiner.
   • Intra-examiner reliability will be assessed.
   • The Intraclass Correlation Coefficient (ICC) will be calculated for radiographic measurements.