The objective of this study is to evaluate the survival of narrow dental implants (≤ 3,5 mm) in multiple fixed prostheses in comparison with standard diameter dental implants (≥ 3,75 mm) after 5 years of follow-up. The hypothesis of the study is that narrow dental implants under the evaluated conditions, have the same survival rate and clinical performance than the standard diameter implants.

Inclusion Criteria:

• Patients of legal age (>18 years) of both sexes.
• Clinical need of multiple fixed alveolar ridge rehabilitations.
• Clinical suitability to insert, at least, one narrow dental implant splinted to a standard diameter dental implant.
• Signature of the informed consent

Exclusion Criteria:

• Presence of an active infection
• Being under active treatment with, or have received in the las 30 days treatment with radiotherapy, chemotherapy, immunosuppressors, systemic corticosteroids and/or anticoagulants.
• Presence of severe haematologic disorders.
• Chronic treatment with non steroidal anti-inflammatory drugs (NSAID) or other aniinflammatory drugs.
• Previous diagnosis of chronic hepatitis or liver cirrhosis.
• Presence of Diabetes mellitus with improper metabolic control (glycosylated haemoglobine higher that 9%).
• Patients subjected to dialysis.
• Presence of malignant tumours, haemangioma or angioma in the surgical area.
• History of ischaemic cardiopathy in the las year.
• Pregnancy or plan to getting pregnant during the study.
• Metabolic bone disease
• Patientd receiving treatment with oral or intravenous biphosphonates.
• Any other condition incompatible with the participation in the study,