Platform Switched Implant and Bone Level Alteration

Study Overview
=================
Brief Summary
-----------------
This is a two-year prospective randomized clinical study to to evaluate whether the gingival thickness and insertion depth of dental implants have any influence on marginal bone levels changes around platform switched implants.

Detailed Description
-----------------
Patient selection: Patients at the Department of Oral Implantology, Peking University School and Hospital of stomatology, Bei Jing, China, who seek for implant restoration for two continous posterior teeth are potentially recruited. Inclusion criteria are generally healthy (ASA score I), non-smoking, periodontally healthy, and sufficient bone volume to place an implant without augmentation procedure. Patients were excluded in cases of medical and/or psychiatric contraindications, local infection, pregnancy or lactating, poor oral hygiene, tissue deficiency, or not willing to participate in this study. Randomization: The two implant sites of each subject are randomly assigned to two different group with a predefined randomization tables. In order to reduce the chance of unfavorable splits between groups in terms of key prognostic factors,the randomization process will take into account the following variables: patient's gender, age, presence of adjacent teeth, distal extension sites and site location in the dental arch. Assignment will perform using a sealed envelope. Surgical protocol: Before the surgical procedure, prophylactic antibiotics of 1g amoxicillin will prescribed to the patient 1 h before surgery, and continued with 2 g/day for 6 days. After crestal incision, full thickness buccal flap was raised, whereas lingual part was not elevated. Thickness of soft tissues was measured with 1.0-mm marked periodontal probe on the top of bone crest in the center of the two future implant sites. This ensured direct visibility of mucosal thickness during measurement. After measurements, full-thickness lingual flap is raised and subsequent implant osteotomy is finished, Two dental implants (Dentsply Implants Manufacturing GmbH, Mannheim, Germany) with diameter of 3.5 mm are ready to torch into the bone cavities. In one site (group 1), the platform of implants are placed at the crestal level (flush to the alveolar ridge) . In the other site (group 2), the implants are placed 1mm below the alveolar ridge. narrow healing abutment are connected to all the implants. The flap are repositioned and closed with interrupted single sutures. Implants are allowed for a un-submerged healing. 3 month after healing, the implant level impressions are taken, splinted restorations of two neighbouring posterior teeth are delivered 2 weeks later. Radiographic and Clinical Examination: All the patients are required for recall visit at 3, 6,12 months and 2 years post surgery. A digital peri-apical radiograph was taken at the 1 year and 2year follow-up examination for bone level evaluation using a film holder to aim the x-ray beam perpendicular to the implant threads, and the implant length is used as calibration for the measurement. Using a image analysis software (ImageJ, version 1.47, NIH, Bethesda, MD, USA), the investigators are able to have an accurate assessment of the crest of bone and to analyze the bone changes over period of time. Bone loss was defined as a positive value and bone gain as a negative one. Mean values, standard deviations, and maximum and minimum values were calculated. Furthermore, periodontal parameters [bleeding on probing (BOP), probing pocket depth (PPD), modified plaque index on adjacent teeth and implants] were assessed.

Official Title
-----------------
Influence of Soft Tissue Thickness and Insertion Depth of Platform Switched Implants on Crestal Bone Level Alteration

Conditions
-----------------
Edentulous, Bone Resorption

Intervention / Treatment
-----------------
* Procedure: Subcrestal implant placement
* Procedure: Paracrestal implant placement
* Drug: prophylactic antibiotics
* Device: dental implant
* Radiation: x-ray examination


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: lose of two posterior teeth more than 3 months generally healthy (ASA score I) non-smoking periodontally healthy sufficient bone volume to place an implant without augmentation procedure Exclusion Criteria: medical and/or psychiatric contraindication to dental implant restoration local infection pregnancy or lactating poor oral hygiene tissue deficiency

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Subcrestal<br>implants that are placed below the alveolar ridge | Procedure: Subcrestal implant placement<br>* Dental implants placed 2 mm below the alveolar ridge<br>Drug: prophylactic antibiotics<br>* amoxicillin was used before and after implant surgery for prophylactic reasons<br>Device: dental implant<br>* dental implants (Ankylos® system,Dentsply Implants Manufacturing GmbH, Mannheim, Germany) were surgically placed into the edentulous alveolar ridge<br>Radiation: x-ray examination<br>* radiographies were taken before treatment and at different time point during the follow-up period<br>|
| Other: Paracrestal<br>implants that are placed flush to the alveolar ridge | Procedure: Paracrestal implant placement<br>* Dental implants placed flush to the alveolar ridge<br>Drug: prophylactic antibiotics<br>* amoxicillin was used before and after implant surgery for prophylactic reasons<br>Device: dental implant<br>* dental implants (Ankylos® system,Dentsply Implants Manufacturing GmbH, Mannheim, Germany) were surgically placed into the edentulous alveolar ridge<br>Radiation: x-ray examination<br>* radiographies were taken before treatment and at different time point during the follow-up period<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes of marginal bone levels of dental implant | Mesial and distal marginal bone level alterations at different time point compared with the base line. Marginal bone levels were measured with an image analysis software to the accuracy of 0.01 mm and the implant length is used as calibration for the measurement. | 3 months, 6 months, 1 year and 2 years post intervention (implant surgery) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Bleeding on probing(BOP) | bleeding index whiling probing the implant restorations | 3 months, 6 months, 1 year and 2 years post intervention (implant surgery) | 
| Probing pocket depth(PPD) | probing depth of implant supported restorations | 3 months, 6 months, 1 year and 2 years post intervention (implant surgery) | 
| modified plaque index(PI) | Modified plaque index to evaluate the oral hygiene conditions | 3 months, 6 months, 1 year and 2 years post intervention (implant surgery) | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
platform switching, crestal bone remodeling, soft tissue thickness, dental implant