Customized Impressions in Dental Implants - Soft Tissues Changes

Soft Tissue

intra-oral scanner, customized impression coping, extra-oral scanner, accuracy

Six patients with a single unit implant in the anterior maxilla (from premolar to premolar), after at least 3 months with provisional implant supported restoration will be submitted to definitive implant impressions. Informed consents and local ethical committee clearance will be obtained. Patients will be submitted to a silicon impression with a customized impression coping from which a conventional cast will be obtained and scanned with D2000 (3Shape) and to an intraoral scan with Trios (3Shape). Standard Tessellation Language (STL) files will be obtained from both procedures and imported to reverse engineering software Geomagic Control X (3D Systems) and the distance between both scans will be calculated in a colored 3D map. From this map, two outcomes will be analyzed: the changes in soft tissues around implants with the two techniques (primary outcome) and the discrepancy between both scans in the teeth adjacent to the implants (secondary outcome).

Custom-guided tissue healing with o provisional restoration is the most predictable way to achieve natural anatomically shaped tissue and optimal esthetics. Several authors describe the use of an anatomically contoured provisional restoration to start to guide the soft tissue healing in an ideal, natural morphology that replicates the tooth form. Being that, after shaping the tissue to ideal anatomic form and health the exact duplication of the soft tissue contour should be obtained so that laboratory can duplicate it in the final restoration. Nowadays gold-standard, describes the use of a customized impression coping that replicates the provisional soft tissue contour by the use of and analog-silicone index upon which a gypsum cast is created. The use of computer-aided design/computer-assisted manufacture (CAD/CAM) technologies to manufacture prosthetic frameworks on dental implants is noticeably increasing. This method requires the use of an STL file which can be acquired intra-orally or extraorally using a stone cast poured from a conventional implant impression using a customized implant impression coping. Several studies have already described the accuracy of STL data and that evaluating STL models can be done by best fit algorithms in appropriate softwares. In this pilot study, the investigators aim to evaluate soft tissue profile changes in single unit implants in the aesthetic area using a customized impression coping with conventional methods and the intraoral impression with an intraoral scanner (Trios, 3Shape). Additionally position discrepancies of adjacent teeth between the two techniques will be assessed. This pilot study will include 6 patients with single unit implant which will be recruited according inclusion criteria and submitted to the two different impression techniques. Conventional stone cast will be scanned with a laboratory scanner D2000 (3Shape) with a described deviation of 5μm. Two STL files will be obtained per patient and by established methods with a reverse engineering software (Geomagic Control X, 3D Systems) discrepancies between them assessed. Differences in axis (x, y, z) and overall distances will be assessed in the soft tissues (18 points) and in adjacent teeth (26 points) according established methods, per patient. Additionally, 3D colored maps will be produced to ascertain volumetric changes between techniques. T-test and Wilcoxon signed-rank test will be used and the level of statistical significance set at P\<0.05. Sample size determination will be performed based on obtained results.

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