Impression of Subgingival Dental Preparation Can Be Taken with Ultrasound.

Because of its ability to capture hard structures behind soft tissue, ultrasound-based micro-scanning may be a promising alternative for taking digital impressions of teeth, especially in the case of subgingival margin preparations. The aim of this study was to assess the accuracy of ultrasound impressions taken of subgingivally prepared teeth compared with digital optical impressions. Ten extracted human teeth (7 pre-molars, 3 molars) were prepared for crowns with chamfer finish line and then digitized using two different intra-oral scanners (Cara Trios, 3 Shape, Heraeus Kulzer, Hanau, Germany; and Lava COS; 3M ESPE, Seefeld, Germany) and one extra-oral scanner (Cares CS2, Straumann, Basel, Switzerland).

Accuracy of single crowns fabricated from ultrasound digital impressions.

Objective: This in vitro study aimed to evaluate marginal and internal fit of single crowns produced from high-frequency ultrasound based digital impressions of teeth prepared with finish lines covered by porcine gingiva, in comparison with those obtained by optical scanners with uncovered finish lines.

Methods: Ten human teeth were prepared and forty zirconia crowns were fabricated from STL-datasets obtained from four dental scanners (n=10): extraoral CS2 (Straumann), intraoral Lava COS (3M), intraoral Trios (3Shape) and extraoral ultrasound scanner. The accuracy of the crowns was compared evaluating marginal and internal fit by means of the replica technique with measurements in four areas; P1: occlusal surface; P2: transition between occlusal and axial surfaces; P3: middle of axial wall; and P4: marginal gap.

Soft tissue-preserving computer-aided impression: a novel concept using ultrasonic 3D-scanning.

Subgingival preparations are often affected by blood and saliva during impression taking, regardless of whether one is using compound impression techniques or intraoral digital scanning methods. The latter are currently based on optical principles and therefore also need clean and dry surfaces. In contrast, ultrasonic waves are able to non-invasively penetrate gingiva, saliva, and blood, leading to decisive advantages, as cleaning and drying of the oral cavity becomes unnecessary.

High-frequency ultrasound as an option for scanning of prepared teeth: an in vitro study.

Because of its ability to non-invasively capture hard structures behind soft tissue, high-frequency ultrasound (HFUS)-assisted microscanning could be a patient-friendly and promising alternative for digitization of prepared teeth. However, intra-oral HFUS microscanners for taking digital impressions of prepared teeth are still not available in the clinical setting. Because working range, scanner size, scanning time, surface reconstruction accuracy and costs are major factors in such a system, our overall objective is to minimize hardware efforts and costs while maintaining the accuracy of the surface-reconstructed tooth model in the range 50 μm.