The aim of this study is to test the use of a bovine-derived bone graft combined with a polynucleotides-rich hyaluronic acid (PNHA) gel for the preservation of the bone after a tooth extraction (alveolar ridge preservation) and to test the performance of a fully-digital workflow to rehabilitate the site with a dental implant. 40 patients in need for a single tooth extraction will be recruited at Centro di Odontoiatria, Università di Parma and they will be randomly assigned to 2 groups: extraction and spontaneous healing or extraction and regeneration of the site with a bovine-derived bone graft combined with a PNHA gel. At 4 months after extraction an implant will be placed in the extraction site, which will be rehabilitated with a fully-digital workflow and patients will be followed up at up to 12 months post rehabilitation. Two 3D x-rays with a small field of view will be performed immediately after extraction and at 4 months post extraction to plan implant placement. These images will also be used to assess changes in the dimension of the post extraction bone (primary outcome). As part of the study different questionnaires will be administered to assess quality of life and perception of the therapy and the wound exudate in the area of the extraction will be collected non invasively with a collagen sponge to assess the expression of different proteins during the early healing days. On the day of implant placement a sample of bone tissue will also be collected as part of the bone drilling and histologically analysed.

This is a single-centre, double-blind RCT involving 40 patients in need for a single tooth extraction to be replaced with a dental implant. The study consists of 11 visits, over a minimum period of 20 months. Participants will be recruited at Centro di Odontoiatria, at Università di Parma amongst patients routinely seen in new patient clinics and follow-up clinics. After atraumatic tooth extraction, participants will be randomly allocated to one of the following treatment groups: - DBBM (Bio-oss, Geistlich) mixed with a PNHA gel (Regenfast, Mastelli) and socket sealed with a porcine collagen matrix (Mucograft seal, Geistlich) (Test); - Unassisted socket healing (Control). Patient post-operative discomfort will be assessed with a visual analogue scale (VAS) and through clinician-reported post-operative oedema/swelling. Clinical evaluation of socket healing and recording of soft tissue healing index of Landry will also be performed during the early post-extraction days. With the help of a sterilecollagen sponge, wound exudate will be collected at 3, 7 and 14 days post extraction. A CBCT with a small field of view (e.g. 5X8 cm) will be taken to assess the post-extraction socket dimensions and after 4 months to plan implant placement. The CBCT scan will be processed with its embedded segmentation function to remove scattering defects and obtain the maximal possible quality.

Changes in alveolar ridge width from the extraction until 4 months post extraction between the 2 groups will be assessed with a dedicated software (e.g. SMOP) (primary outcome).

On the day of implant placement, a bone core biopsy will be collected from the drilling site. Undecalcified histology analysis will be done, and qualitative histology will be performed by a blind examiner, who will assess the level of maturation of the tissue in the two groups. Moreover, histomorphometric measurements will be recorded and presented descriptively, including amount of mineralized bone, as well as other standard parameters, such as %graft particles (test group only) and % of immature woven bone. A fully digital workflow will be followed to rehabilitate the patients, which will be followed up at up to 12 months post implant loading.

Inclusion Criteria:

• ≥25-year-old males and females;
• good systemic health (self-assessment);
• presence of an unrestorable/hopeless tooth with periodontal attachment and buccal bone preserved at least for 2/3rd of the root and not associated with acute periapical pathology;
• full mouth bleeding and plaque scores ≤ 25%

Exclusion Criteria:

• uncontrolled or untreated periodontal disease;
• history of local (head and neck) radiation therapy in the past 5 years;
• acute endodontic lesion in the test tooth or in the neighbouring areas to the extraction procedure (sites with presence of an asymptomatic chronic lesion are eligible);
• medical history that includes uncontrolled diabetes or hepatic or renal disease, or other serious medical conditions that can impact on bone metabolism (e.g. rheumatoid arthritis, osteoporosis) or transmittable diseases (e.g. HIV-related disease);
• history of alcohol or drug abuse;
• smokers of ≥10 cigarettes a day;
• self-reported pregnancy or lactation.

All patients' data held will be coded and pseudo-anonymised with an alphanumerical code that will be kept separately from the personal data as name, surname, date and place of birth and sex and stored in a locked cabinet in the PI's office.

The only people within the Centro di Odontoiatria who will have access to information that identifies the patients will be people who need to contact them about the research study, and make sure that relevant information about the study is recorded for their care, and to oversee the quality of the study or audit the data collection process. The people who analyse the information will not be able to identify patients and will not be able to find out their name or contact details.