The Role of a New Prosthodontics Device in Hard and Soft Tissue Changes After Subcrestal Implant Placement

The present randomized controlled trial aims to assess the influence of a new prosthodontics device (Gingival Former Abutment -GFA) on peri-implant bone loss and soft tissue changes and health after subcrestal oral implant placement.

The participants will be divided in two groups and receive either crestal implant placement and traditional healing abutment or subcrestal implant placement and GFA.

Clinical and radiographic examination will be performed at implant placement surgery, prosthetic load, 6 and 12 months follow-up.

According to current literature, physiological bone loss around oral implants is expected after placement and load (1 mm during the first year and 0.2 mm each subsequent year). Different implant designs and surgical protocols have been tested to minimize bone resorption, and subcrestal implant placement partially seems to overcome this issue. However, if this procedure increases the length of the transmucosal tunnel, increasing the risk of peri-implant soft tissue infection.

The GFA was created to limit both the loss of peri-implant crestal bone and the extension of the transmucosal tunnel. The GFA follows the "one abutment one time" concept, which is believed to limit disturbances of the peri-implant hard and soft tissues healing due to the removal of the traditional healing abutments during prosthetic load procedures. Our objective is to validate or deny this claim.

The study is a monocentric, pragmatic, single-blinded, randomized clinical trial (RCT) of parallel design. The trial will have a one-year duration, with data collection at the surgical phase, at implant load and 6 and 12 months after load. The primary outcome will be radiographical MBL (marginal bone level) changes around the implant. Secondary outcomes will be the assessment of the peri-implant soft tissues.

Eligibility Criteria:
Inclusion Criteria:

* Ability to comprehend and sign informed consent.
* Male and female subjects, aged 18-75 years, inclusive.
* Good general health (free of systemic diseases such as diabetes, HIV infection or genetic disorder, ongoing malignant disease of any type that could influence the outcome of the treatment and might interfere with the evaluation of the study objectives).
* Good oral health (no decay, periapical or periodontal lesions, PI and BOP \<25%).
* Patient with posterior single missing tooth:

  * for at least 5 months,
  * mandibular or maxillary,
  * intercalated (distance between teeth more than 7.5 mm),
  * at least 11 mm of height residual bone (from bone crest to maxillary sinus or inferior alveolar nerve),
  * at least 5 mm of bone width (buccal - palatal/lingual).
* Availability for the 12-month duration of the study.

Exclusion Criteria:

* Not willing to follow the agreed protocol.
* Presence of orthodontic appliances.
* Smokers more than 10 cigarettes per day.
* Chronic obstructive pulmonary disease and asthma.
* Tumors or significant pathology of the soft or hard tissues of the oral cavity.
* Current radiotherapy or chemotherapy.
* Pregnant or lactating women.
* Parafunctions like bruxism.
* Previous interventions to increase bone thickness in the implant area.
* Current or past assumption of medications that may influence surgical therapy and/or interfere with healing following surgical treatment.
* Systemic diseases that constitute a contraindication to surgical therapy and/or interfere with healing following surgical treatment.