NDI represent an advisable treatment option when the mesio-distal space is compromised. In a recent retrospective study with a follow-up of 8 years in which they wanted to evaluate the long-term survival, complications, peri-implant conditions, marginal bone loss, and patient satisfaction of fixed dental prostheses supported by NDI in the posterior area. They observe a survival rate of 97% and absence of prosthetic complications after the study period time. More recently, Souza et al. performed a prospective randomized split mouth study with 3 years follow-up with the aim of comparing marginal bone level, implant survival and success rates and prosthesis success rates of NDI and SDI placed in the posterior area of the mandible to support single prosthesis. They observed an implant survival rate of 100% for both groups at 1 and 3 years. The prosthesis success rate at 1 and 3 years was of 95.4% and 100%, respectively.

NDI present a high survival rate on the evaluated studies. Therefore, the aim of the first study is to compare the patient related outcomes, implants and prostheses success and survival rates of pure titanium NDI versus SDI with simultaneous bone regeneration in narrow alveolar ridges at posterior areas of the maxilla and the mandible.

Inclusion Criteria:

Patients:

• 18 years old
• Healthy periodontal status (absence of generalized probing pocket depth (PPD) <4mm)
• Oral hygiene levels (FMPS <20 and FMBS <20)

Site:

• Ridge width of >5mm and <6.5mm and minimum bone height of 10mm prior evaluation on a CBCT scan
• Presence of antagonistic natural tooth or fixed prosthetic restoration
• Presence of adjacent teeth
• One maxillary or mandibular premolars
• Minimum of 3mm of keratinized tissue over the bone crest (20)
• Bone regeneration within the limits of the prosthetic restoration.

Implants:

• Unitary prosthesis
• Screwed retained restorations

Exclusion Criteria:

Patients

• Presence of active chronic or aggressive periodontal disease
• Presence of systemic disease which contraindicate surgery (patients with an ASA ≥ 3)
• Drugs or medications which may alter the results (chronic intake of analgesic medication)
• Smokers (>10cig/day)
• Pregnant women
• History of head and neck radiotherapy.

Site

• Anterior area (from 1.3 to 2.3 and from 3.3 to 4.3) and molar area
• Previous guided bone regeneration
• Location where there is not sufficient restorative space (mesio-distally <8mm for every restoration unit and <5mm from the bone crest to the antagonist)
• Implant dehiscence of more than 2/3 of the implant.

Implant

• Implants which cannot be restored with a screwed restoration
• Implants which doesn't reach a manual implant stability
• implants which after placement doesn't reach a favourable position according to the restoration.