Changes of Soft and Hard Tissues After Alveolar Ridge Preservation: Freeze-dried Bone Allograft vs. L-PRF Clot

A prospective,randomized clinical trial will be conducted to determine whether L-PRF, compared to freeze dried bone allograft, will result in comparable volumetric shrinkage of the alveolar ridge and overlying keratinized tissue, following extraction of teeth and socket grafting.

This trial aims at obtaining information to determine which material would provide a superior clinical result, as well as reporting on patient related outcomes. The participants will be randomly assigned to two groups. The surgical procedure will be performed by one of five calibrated periodontal residents.

Patients will be followed for 2 weeks post-operatively by the same resident, to monitor the healing process and to assess for any complications.

Randomization will be achieved using a computerized randomization scheme and will be assigned to one of two groups and allocated by means of a sealed envelope opened on the day of surgery communicated to the surgeon during the surgery by a supervising faculty member. Participants will be block-randomized for each of the 5 operators for balance.

Anesthesia will be achieved and soft tissue measurements will be obtained using a periodontal probe. An atraumatic extraction technique will be performed to allow for minimal disturbance of the soft and hard tissue architecture.

The extraction socket walls are then assessed and any defects in socket measured with a periodontal probe. Group A: Full thickness mucoperiosteal pouch is created up to ~3mm apical of the bony crest of the socket with a periosteal elevator. The socket is incrementally filled with mineralized cortical freeze-dried bone allograft and condensed. Group B: Socket is pouched as in group A followed by venipuncture of the antecubital vein with 21G needle and collection of 4-6 vials (10ml each) of venous blood without any additive or anticoagulant. The vials are centrifuged for 12 minutes at 2700 rpm to form L-PRF clots. The socket is incrementally filled with the clots and condensed.

Following socket fill, both groups will have the grafts covered by dense polytetrafluoroethylene membrane. The membrane is trimmed and adapted with the borders tucked 2-3mm underneath the gingival tissues. Tissues, graft and membrane are stabilized with 5/0 PTFE sutures.

The patients will also receive a pain VAS questionnaire evaluating the post-operative pain 1 and 7 days following surgery. A CBCT with the radiographic stent will be taken within 72 hours of the surgery.

7 days post-op: Sutures will be removed if deemed suitable. The VAS questionnaire will be collected.

6 weeks post op: d-PTFE membrane will be retrieved and discarded using tissue forceps. Alginate impressions will be taken for a surgical guide.

11 weeks post op: Second CBCT will be taken with radiographic surgical stent. Images obtained will be used to analyze and compare the ridge dimensions to those obtained at baseline as well as for surgical implant planning.

12 weeks post op: Soft tissue measurement with periodontal probe and floss spanned over edentulous site from buccal to lingual mucogingival junction. Implant placement will be done per standard procedure. A 2.5mm diameter trephine drill will be used to harvest a bone core for histologic analysis. The bone core will be immediately submerged in a solution of 10% neutral buffered formalin. Osteotomies and implant placement will be done following the manufacturer's protocol. Depending on the buccal bone and soft tissue thickness, ancillary soft tissue augmentation, bone augmentation or combination of these procedures may be indicated. The patient will be followed up and referred to the restorative dentist as per standard procedure. Photographs will be taken at every visit.

Inclusion criteria

• Subjects with molars or premolars indicated for extraction.
• Patients that present with a post extraction class I and II socket (<30% bone loss on the buccal or lingual plate, measured from the most coronal aspect of intact bone to the most apical aspect of the defect divided by the measurement from the most apical aspect of the defect to the apex of the socket x 100).
• Patients presenting with the need for single extractions.
• Patients with general good health that does not have a condition contra-indicating routine dental treatment, extraction and implant placement.
• Patients that are compliant with the research protocol and methods.
• Patients that have read, understood and signed an informed consent form.

Exclusion criteria

• Extraction and ridge preservation indicated for teeth other than premolars and molars.
• Patients that present with a post extraction class III socket (>30% bone loss on the buccal or lingual plate, measured from the most coronal aspect of intact bone to the most apical aspect of the defect divided by the measurement from the most apical aspect of the defect to the apex of the socket x 100)
• Patients deemed eligible for immediate implant placement following extraction and intra-operative assessment by the attending supervisor.
• Patients that present with an oral-antral communication, post extraction.
• Patients that presents with the need for multiple, side by side extractions.
• Patients with coagulation disorders, on corticosteroids, uncontrolled diabetes mellitus, or any systemic disease where periodontal surgery is contraindicated and healing may be compromised.
• Pregnant and nursing women.
• Patients with any contact hypersensitivity to the related materials used in the study.
• Heavy tobacco users, >10 cigarettes per day.
• Patients unwilling to sign consent or follow the protocol of the study.