Digitale Zahnabformung mittels hochfrequenten Ultraschalls

  • Digital dental impressioning by means of high-frequency ultrasound

Chuembou Pekam, Fabrice; Radermacher, Klaus (Thesis advisor); Tinschert, Joachim (Thesis advisor)

Düren : Shaker Verlag (2021)
Book, Dissertation / PhD Thesis

In: Aachener Beiträge zur Medizintechnik 62
Page(s)/Article-Nr.: vi, 146 Seiten : Illustrationen, Diagramme

Dissertation, RWTH Aachen University, 2020


Computer-aided dental prosthesis manufacturing has gained more and more importance in the last decade in dental practices and dental laboratories, not least because of its high degree of standardization, the use of high-quality dental prosthesis materials and the associated delivery of aesthetically and functionally optimized dentures. Technological advances today do not only allow digital manufacturing (CAM - Computer Aided Manufacturing), but also a direct digital impression of the clinical situation by means of light-optical methods and the production of the digital tooth model based on this (CAD - Computer Aided Design). However, impression-taking of subgingival tooth preparations is still one of the greatest challenges for currently available impression-taking methods and poses high health risks for the patient due to the invasive uncovering process of the gingiva. In addition, a great deal of time is required to stop bleeding and dry out the oral cavity before taking the impression. In the present work, a novel method for digital impression taking of prepared teeth by means of high-frequency ultrasound in the context of CAD-CAM-supported production of crowns was developed. The focus was on the protection of the gingiva by eliminating the retraction measures as well as on the reduction of the negative impact of liquids on the impression process. A requirement analysis as well as an analysis of the state of the art in ultrasonic technology led to the selection of a high-frequency single-element transducer as the recording sensor. This resulted in a scanner concept with only two degrees of freedom. The resulting limited lateral resolution could be successfully addressed by the development of resolution optimizing algorithms. By selecting suitable segmentation and meshing approaches, the 3D geometry of the tooth stump was reconstructed based on the optimized ultrasonic data. The final in vitro study not only showed that subgingival tooth preparations can be recorded by high-frequency ultrasound without gingiva retraction, but also that this can be done within the clinically required accuracy.