Association Between Restorative Emergence Profiles and Peri-implant Bone Loss in Different Implant Systems:

The goal of this observational study is evaluate the association between different emergence profile angulation on marginal bone loss progression around different implant systems (bone level, tissue level and switching platform).

Does different emergence profile angulation have the same effect on peri-implant marginal bone loss? Standardized periapical radiograph that were captured after crown placement on implants will be compared with the new radiographs done after recalling the patient.

The present retrospective study reported the data collected on partially edentulous patients who were restored with fixed implant supported restorations. The implants were inserted in the periodontology department at the Faculty of Dental Medicine at the Saint Joseph University of Beirut, Lebanon, from 2012 to 2019. The study protocol received approval from the Institutional Review Board at Saint Joseph University of Beirut.

Under the guidance of academic members, all surgical procedures were carried out by postgraduate students. For each implant system, the surgical procedure followed the conventional recommendations. Patients got cemented or screw-retained fixed prostheses after adequate healing time of 3 to 6 months.

Patients were urged to practice proper oral hygiene after receiving their final crown. Even though all patients are told to participate in a regular Supportive periodontal therapy program, some of them did not, they were not selected and excluded in this study Patients or implants were excluded under the following conditions: (a) insufficient clinical records; (b) patients with systemic diseases or conditions; (c) smokers; (d) irregular maintenance care; (e) patients with calculus presence on radiographs; (f) implants placed on reconstructed sites; (g) implant-assisted removable prostheses; (h) peri-implantitis diagnosis; (i) failed implants;(j) Bone loss before prothesis delivery (k) previously treated peri-implantitis cases; and (l)Bone level implants placed supracrestally; (m) lack of intra-oral radiographs taken using the paralleling technique at baseline (the first year of prosthesis insertion) and after 3 years.

Patients were called for reassessment appointments after 3-7 years. After signing the informed consent, measurements by a PCP-15(periondontal probe) probe of plaque index (FMPS) and bleeding on probing (FMBS) are indicated on the form. If the smoking status has changed, it is also mentioned.

For data analysis, the following categories were included: implant connection type (bone-level platform switching, bone-level non platform switching, or tissue level); Emergence Angle (mesial and distal, separately); Emergence Profile (mesial and distal, separately); location; history of periodontitis, abutment height. Radiographic and clinical parameters taken at the time implant placement, after prosthetic delivery, and following a minimum of 3 years follow-up visit were provided.

Single and multiple restorations were included.

Eligibility Criteria:
Inclusion Criteria:

* Patients who have undergone the initial phase followed by implant placement.
* Implants placed and prosthesis delivered for more than 3 years.
* Implants placed in premolar/molar region
* No reconstructive bone procedure done on the site of study
* Presence of opposing occlusion
* Non-smokers

Exclusion Criteria:

* Systemic diseases (uncontrolled diabetes, drugs that can affect bone metabolism).
* Total edentulousness.
* Inappropriate, unavailable, or distorted x-rays.
* Implants placed at a supra or infra bone level.
* Implants placed immediately after an extraction.
* Poor oral hygiene (High plaque score FMPS control record \> 30%)
* Smokers
* Signs of peri-implantitis development during the first year following functional loading
* Lack or incomplete information regarding peri-implant conditions (clinical and radiographic documentation at the required study time-points)
* Surgical treatment on the study implants during the first 2 years after peri-implantitis diagnosis