Apico-coronal Position of Tissue-level Implants Bone Stability

Study Overview
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Brief Summary
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early marginal bone loss around dental implants may hamper long term prognosis of implant-prosthetic rehabilitation. this study aimed to study the correlation of pico-coronal position of dental implant (from supracrestal, crystal to undergone level) measuring early marginal bone loss through periapical x-ray at surgical time and subsequent follow-ups.

Detailed Description
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Early marginal bone loss (EMBL) is a non-infective remodeling process of peri-implant crestal bone occurring within the first year after implant insertion. EMBL has a multifactorial etiology, being influenced by various surgical and prosthetic factors, including insufficient crestal width, surgical trauma, biological width formation, microbial colonization of implant-abutment micro-gap, horizontal implant-abutment mismatch (the platform-switching concept), the number of abutment connection/disconnections, prosthetic abutment height, design and mechanical stability of implant-abutment connection and adaptive response to occlusal loading. Biological width formation is the main factor influencing peri-implant marginal bone adaptive processes prior to prosthesis delivery. When an implant gets exposed to the oral cavity, soft tissues establish a cuff-like barrier sealing the trans-epithelial component of the fixture. Differently from equicrestal and subcrestal implants, which present a microgap between implant and abutment at the marginal bone level, tissue-level implants have no gap at this region. The present multicenter prospective study aims to evaluate if EMBL occurring around tissue-level dental implants before prosthesis delivery may be reduced by adapting apico-coronal positioning in relation to supracrestal tissue thickness. All patients are treated according to one-stage implant. Sutures are removed 12-14 days after surgery. No removable prostheses are utilized during the healing period. Final impressions were taken five months after the implant placement. After functional and aesthetic try-in, a single-unit screw-retained metal ceramic crown is delivered. The fixation screw was torqued to 30Ncm following manufacturer's guidelines. Screw access is then closed using light-cured composite resin. Radiographic measurements. Digital radiographs, customized for each patient with a bite jig, are taken using a long-cone paralleling technique with a film holder at the time of implant placement (baseline, T0), 3 months after implant placement (T1), and 5 months after implant placement, immediately before impression taking (T2). All radiographs are performed using the same x-ray generator technology, set with the same parameters (60 kV, 7 mA). Two different types of bone changes are calculated, as suggested elsewhere. Early marginal bone loss (EMBL) is calculated. Bone Loss Exposing Implant Surface (BLEIS) is calculated as the difference between the EMBL measurement and the 3 mm length of the transmucosal, machined portion of the implant. Radiographs demonstrating any deformation, darkness and/or other problem are immediately repeated. All measurements are made by a single calibrated examiner, blind to mucosal thickness, using a 30-inch led-backlit color diagnostic display with Kodak Digital Imaging Software. Each measurement is repeated three times at three different time points as proposed by Gomez-Roman and Launer. Intra-examiner and inter-examiner concordances are 96.1% and 90.4%, respectively, for linear measurements within ±0.1mm.

Official Title
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Influence of the Apico-coronal Position of Tissue-level Implants on Marginal Bone Stability

Conditions
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Bone Atrophy, Alveolar

Intervention / Treatment
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* Procedure: implant insertion


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients were partially edentulous and required placement of at least one single delayed implant in pristine bone in the posterior mandible presence of keratinized mucosa with a minimum bucco-lingual width of 3 mm; bone crest with at least 6mm of width and 9 mm of height above the mandibular canal without concomitant or previous bone augmentation procedures; presence of the opposing dentition Exclusion Criteria: smokers uncontrolled periodontitis medication consumption for at least 3 months prior to treatment history of head or neck radiation therapy pregnancy or lactating at any time during the study

Ages Eligible for Study
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Minimum Age: 20 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| thin crestal mucosa<br>Based upon vertical mucosa thickness measured at implant placement, implants were placed: 2mm below the crestal bone in presence of thin mucosa (< 2.5mm) | Procedure: implant insertion<br>* 4% articaine solution, a mid-crestal incision along the center of the edentulous bone ridge was performed. A full-thickness flap was elevated. The sites were prepared to permit insertion of transmucosal, external hex, implants (I-smart, I-RES, Lugano, Switzerland) at three different crestal levels, based upon vertical mucosa thickness measured at implant placement. Owing to width crest, all implants were 3.75 mm in diameter and operators selected appropriate implant lengths (8, 10 mm) according to available bone crest height. All implants were not submerged and flaps were sutured around the transmucosal component.<br>|
| medium crestal mucosa<br>Based upon vertical mucosa thickness measured at implant placement, implants were placed: 2) 1mm below the crestal bone in presence of medium mucosa (2.5-3.5mm); | Procedure: implant insertion<br>* 4% articaine solution, a mid-crestal incision along the center of the edentulous bone ridge was performed. A full-thickness flap was elevated. The sites were prepared to permit insertion of transmucosal, external hex, implants (I-smart, I-RES, Lugano, Switzerland) at three different crestal levels, based upon vertical mucosa thickness measured at implant placement. Owing to width crest, all implants were 3.75 mm in diameter and operators selected appropriate implant lengths (8, 10 mm) according to available bone crest height. All implants were not submerged and flaps were sutured around the transmucosal component.<br>|
| thick crestal mucosa<br>Based upon vertical mucosa thickness measured at implant placement, implants were placed: 1) at crestal level in presence of thick mucosa (> 3.5 mm); | Procedure: implant insertion<br>* 4% articaine solution, a mid-crestal incision along the center of the edentulous bone ridge was performed. A full-thickness flap was elevated. The sites were prepared to permit insertion of transmucosal, external hex, implants (I-smart, I-RES, Lugano, Switzerland) at three different crestal levels, based upon vertical mucosa thickness measured at implant placement. Owing to width crest, all implants were 3.75 mm in diameter and operators selected appropriate implant lengths (8, 10 mm) according to available bone crest height. All implants were not submerged and flaps were sutured around the transmucosal component.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| early marginal bone loss | distance from crystal bone to most coronal bone to implant contact | 5 months after implant placement | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| biological complications | any surgical complication | during surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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osseointegrated implant; early marginal bone loss;