Primary: Histologically analyse the quality of bone regeneration after graft material insertion in severely resorbed maxilla.

Secondary: Radiological analysis of the volume of the bone regenerations with the shirnkage rate of the graft material. clinical study of 20 patients 13 in OSSIX Bone group 13 in Bio-Oss Collagen group all patients requiring a regenerative procedure (sinus lift) having less than 3mm of residual bone height (RBH) with the impossibility to place the implants at the time of regenerative proc 6 months follow up for the first endpoint. (collection of the histological sample) 12 months follow up - long term clinical evaluation. tests performed: Cone Beam Computed Tomography (CBCT), clinical evaluation, X-ray

Visit 1 - Screening Visit - preoperative visit (informed consent, dental mouth cleaning, CBCT, intraoral scanning).

Visit 2 - Baseline visit - T0 (surgical procedure) Sinus elevation with OSSIX® Bone or Bio-Oss® Collagen, periapical x-ray, intraoral photo with microscope.

Visit 3 - Follow up visit - 14 days - suture removal, clinical evaluation and patient satisfaction questionnaire.

Visit 4 - Follow up visit - 180days (One week before) Cone Beam Computed Tomography (CBCT), Dental mouth cleaning, intraoral scanning.

(Second surgery) implant site preparation and histological sample collection, implant placement, insertion torque value, implant stability, peri-apical x-ray, intraoral scanning and photography.

Visit 5 - Follow up visit - 194 days suture removal and clinical evaluation. Visit 6 - Follow up visit - 270 days Implant stability, clinical examination, definitive restoration and periapical x-ray Visit 7- Follow up visit - 365 days Implant stability, peri-apical x-ray, definitive restoration, Cone Beam Computed Tomography (CBCT), intraoral scanning and picture.

Inclusion criteria:

1. Patient requiring vertical elevation of the maxillary sinus.
2. Residual alveolar bone height of edentulous maxilla below the floor of the maxillary sinus of < 3-4 mm.
3. Males and females between 30-80 years old
4. Patients with healthy periodontal conditions (Treated periodontitis, Plaque Index (PI) <25%, Bleeding on Probing (BoP) <25%).
5. Patients that are willing to sign an informed consent and participate in a clinical Study.
6. Generally fit and healthy and able to undergo oral surgical procedures under local anesthesia.
7. Teeth at the surgical site which required removal were extracted a minimum of 12 weeks prior to sinus floor elevation.

Exclusion criteria:

1. Patient requiring vertical elevation of the maxillary sinus with native bone crest height > 5 mm
2. Patients who smoke over 5 cigarettes/day
3. Pregnancy (confirmed by verbal inquiry)
4. Chronic systemic pathologies (e.g. diabetes) and neoplastic of the Oro-Facial District 4.
5. Patients taking bisphosphonates
6. Any sites where an implant already failed sites
7. Untreated Periodontitis
8. Dental sites with acute infections
9. Chronic inflammatory diseases of the oral cavity
10. Autoimmune diseases (cortisone intake)
11. Allergy declared to one or more medicaments to be used during treatment
12. Alcoholics patients and/or drug addicts
13. Patients with known collagen hypersensitivity.
14. Patients with sensitivity to porcine-derived materials.
15. History or malignant tumors of the maxillary sinus
16. History of local radiation therapy

data will be shared if required

assessors analyzed blindly receiving anonymized bone samples and CBCT