Previous in a randomized way, it will be performance 12 bilateral sinus lift with autologous bone in one side and the in other with xenograft material. After 6 mouths we will place 1 to 3 implants in each side and analyse the survival rate and possibles differences related to; prosthesis failure; biological and prosthetic complications; peri-implant marginal bone level changes.

The study will be performance in 12 patients submitted to a bilateral sinus lift procedure.

Six months after the bilateral sinus lifting performed in a randomly way, using as graft materials (100% of autologous bone graft or 100% of xenograft), will be placed 1 to 3 implants in each maxillary sinus.

Wait more six months to expose the implant. At the end of 13 months after implant placement it should be in charge.

Implant placement (6 months after sinus lift procedure):

• Both sides should be treated during the same session.
• Patients will receive 2g Amoxicillin one hour before the procedure. Patients allergic to penicillin will be given Clindamycin 600 mg 1 hour before implant placement procedure.
• Patients will rinse for 1 minute prior to flap elevation with 0.12% chlorhexidine mouthwash.
• After delivery of local anaesthesia, incision and flap elevation, the recommendation of the various implant manufacturers will be followed for placing 1 to 3 implants 9-11 mm long per posterior upper (premolar-molar areas) below the maxillary sinus and a histological sample for each side will be collected.
• The neck of the implants will be placed flush to the bone and implants will be submerged under the soft tissues and flaps will be sutured.
• Baseline intraoral radiographs of the study implants have to be taken.

Post-implant placement instructions:

• Chlorhexidine mouthwash 0.12% for 1 minute twice a day for 2 weeks.
• Ibuprofen 400 mg will be prescribed to be taken 2-4 times a day during meals, but patients will be instructed not to take them in absence of pain. Patients with gastric problems or allergic to ibuprofen will receive paracetamol 1 g instead.
• Sutures will be removed after 10 days.

Abutment connection (6 months after implant placement):

• Both sides should be treated during the same session.
• Patients will rinse for 1 minute prior to flap incision with 0.12% chlorhexidine mouthwash.
• Mucosa can be punched or a flap will be elevated according to personal preference of the surgeon, it is important that both sides are treated in the same way.
• Individual implants will be tested for stability.
• Impressions will be taken.
• Healing abutments will be placed.

Post-abutment connection instructions:

• Chlorhexidine mouthwash 0.12% for 1 minute twice a day for 2 weeks.
• Ibuprofen 400 mg will be prescribed to be taken 2-4 times a day during meals, but patients will be instructed not to take them in absence of pain. Patients with gastric problems or allergic to ibuprofen will receive paracetamol 1 g instead.
• Sutures will be removed after 10 days.

Prosthetic phase:

• Within one month after abutment connection, implants will be manually tested for stability.
• Provisional reinforced acrylic restorations or definitive screw-retained or provisionally cemented (to allow implant stability assessment) metal-resin or metal-ceramic bridges rigidly joining the 2 or 3 implants will be delivered.
• Implants will be splinted under the same prosthesis, each implant supporting one tooth element.
• The connection of teeth with implants under the same prosthesis is not allowed.
• Similar procedures and materials have to be used in the same patient.
• The occlusal surface will be in slight contact with the opposite dentition.
• Intraoral radiographs and clinical pictures of the study implants will be taken at initial loading.

Maintenance:

• All patients will be recalled every 6 months after prosthetic loading for delivery of professional maintenance on individual basis.
• Dental occlusion will be evaluated at each maintenance visit.

Inclusion Criteria:

• Any partially edentulous patient having bilateral edentulism in the posterior maxillae (premolars and/or molars) with a similar degree of bone resorption requiring one to three implants at each side, being 18 years or older, and able to sign an informed consent. For all the potentially included patients preoperative CBCT (cone beam computed tomography) or CT scans and OPGs (orthopantomograph)must be obtained and attached to the files. The vertical bone height below the maxillary sinus at the implant sites must be of 1-5 mm and bone thickness at least 6 mm measured on CBCT (cone-beam computed tomography)or CT scans. Smokers will be included and patients will be grouped into: 1) non smokers; 2) light smokers ≤ 10 cigarettes/day; 3) heavy smokers ≥ 11 cigarettes/day, according to what they declare.

Exclusion Criteria:

• General contraindications to implant surgery.
• Patients irradiated in the head and neck area.
• Immunosuppressed or immunocompromised patients.
• Patients treated or under treatment with intravenous amino-bisphosphonates.
• Patients with untreated periodontitis.
• Patients with poor oral hygiene and motivation.
• Uncontrolled diabetes.
• Pregnancy or nursing.
• Substance abuser.
• Psychiatric problems or unrealistic expectations.
• Lack of opposite occluding dentition in the area intended for implant placement.
• Patients with an acute or chronic sinusitis.
• Patients participating in other trials, if the present protocol cannot be properly adhered too.
• Patients referred only for implant placement.
• Patient unable to be followed for 5 years after loading.

Seal envelops, codification of the side and patient and independent blind assessors