Dental implants are worldwide recognized one of the best manners to replace lost or hopeless prognosis teeth. There are different variables that creates proper conditions for long-term prognosis of implant treatments.

Implant position and surrounding bone around them, have been described in scientific literature to be key factors in the longevity of those treatments.

It has to be defined the "critical bone thickness" around implants. It basically means that implants has to be completely surrounded by bone, that will serve as protection. If the implants are not surrounded by bone, procedures as guided bone regeneration may be performed.

Those procedures can be executed before or simultaneously during the implant placement. In the standard procedure, the simultaneous guided bone regeneration during implant placement requires to leave the implant and the regeneration healing below the gingiva, needing a second surgery for accesing to those implants.

In this randomized controlled trial the hypothesis is to discover if not submerging this regenerations may show the same results than submerged ones.

For that, the objective is to study the different variables around these regeneration to evaluate the performance of non-submerged protocol.

Inclusion Criteria:

• • Men and women over 18 years old.

  • Patients requiring single-unit implant restoration in any tooth site of the maxilla and mandible in between teeth.
  • Anticipation of a peri-implant buccal osseous dehiscence by means of a CT imaging (cone-beam computed tomography, CBCT) with a maximum vertical dimension height (VDH) of 50%.
  • Presence of adjacent teeth.
  • Presence of antagonist teeth.
  • Minimum primary stability of 25Ncm.
  • Non-smokers or light smokers (< 10 cigarettes per day).
  • Absence of systemic diseases that could influence the outcome of the therapy (i.e., uncontrolled diabetes mellitus, osteoporosis, biphosphonate medication).
  • Tooth extraction performed at least 4 months before implant placement.
  • Good level of oral hygiene (Plaque Index < 25%) (Löe, 1967)
  • Written informed consent signed.
  • Keratinized mucosa of at least 2mm on the buccal and lingual of the implant.

Exclusion Criteria:

• Implant surgery requiring sinus lift procedure.

  • Previous bone augmentation at the implant site.
  • Active periodontal disease.
  • Acute infection at the rehabilitation site.
  • Long-term non-steroidal anti-inflammatory drug therapy (3 months).
  • Lactating females or currently pregnancy.
  • Severe cognitive or psychiatric disorders.
  • Unwillingness to return for follow-up examination.