The loss of a tooth or change in its function is lead to a change in alveolar ridge's height and volume. Socket preservation (SP) is a procedure designed to prevent or limit alteration of the post-extraction bone ridge to achieve an optimal prosthetic implant rehabilitation. The aim of this randomized-controlled clinical trial is to suggest that platelet rich fibrin (PRF) as solely grafting material may be a valid tool in this technique.

80 patients with mandibular or maxillary premolars that need to be extracted will be recruited. All patients will be randomly treated by using two different therapeutic approaches, thereby yielding two different study groups, each of which is composed of 40 cases: in the test group the socket preservation technique with PRF will be performed, in control group the post-extraction socket is left healing spontaneously without performing socket preservation.

A software will be used to produce a random sequence of 80 integer numbers without duplicates generated by a software and concealed in closed envelopes by one of the investigators. At the time of the patient's first surgery, the envelope will be opened and patient allocated either to test or control group. All patients are informed by the written consent obtained that they could be causally allocated to one of the two groups.

Before extraction, patients should undergo to periodontal treatment and instrumental investigations such as orthopantomography.

After local anesthesia (mepivacaine 2%), the tooth is extracted atraumatically with levers and forceps taking care to preserve the bone cortex. The roots of multi-rooted teeth are separated before extraction. The pocket epithelium and the granulation tissue are removed.

In the test group, a blood collection of 40 ml will be performed and PRF is made according to the manufacturer instructions.

One clinician, not involved in patient treatment and not aware of what therapeutic approach used for the different sites of treatment, will perform all clinical measurements immediately after surgery and three months later.

Patients will be checked at 3 days, 1 week after surgery (removal of sutures), 14 days after surgery, 28 days after surgery and at 3 months after surgery (at the time of implant placement).

A Cone Beam Computed Tomography (CBCT) is prescribed immediately after surgery and 3 months after surgery before implant placement.

Differences between the two analysed groups will be evaluate by test t-student through a statistic software.

Inclusion Criteria:

• Mandibular or maxillary premolars that need to be extracted due to endodontic failure, caries or fractures and will need to be replaced with a dental implant after 3 months of healing
• Full mouth plaque score ≤ 25% at onset
• Full mouth bleeding score ≤ 25% at onset
• Integrity of the alveolar walls after extraction
• Vestibular wall thickness < 1 mm
• Patients able to understand and sign informed consensus

Exclusion Criteria:

• Significant medical conditions contraindicating surgery
• Pregnancy and breastfeeding
• Tobacco smoking (>15 cigarettes per day)
• Immunocompromised patients
• Alcohol and drug abuse
• Uncooperative patients
• Periodontally compromised patients
• Acute abscesses at the extraction site
• Other dental elements that are not premolars
• Patients who do not show up for scheduled checkups