Assessment of the trueness of additively manufactured mol3% zirconia crowns at different printing orientations with an industrial and desktop 3D printer compared to subtractive manufacturing

OBJECTIVES

This study endeavours to investigate the effect of printing orientation on the trueness of additively manufactured molar zirconia crowns. The areal surface roughness and the characteristics of the marginal regions of the crowns were also considered.

METHODS

Twelve molar crowns were manufactured at 0°, 45°, and, 90° printing orientations in a Lithoz and AON zirconia printer, respectively. Twelve milled crowns were used as a comparison. Samples were scanned and analysed in metrology software to determine the trueness of the groups. Regions of interest were defined as the margins, intaglio surface and contact points. Areal surface roughness and print layer thickness were further analysed using a confocal laser scanning microscope.

RESULTS

The results indicate that there are clear differences between the investigated desktop (AON) and industrial (Lithoz) 3D printer. The 45° Lithoz group is the only sample group showing no significantly different results in trueness for all regions analysed compared to the milled group. Areal surface roughness analysis indicates that the print layers in the marginal regions are within clinically tolerable limits and surface characteristics.

CONCLUSIONS

The printing orientation for zirconia crowns is critical to trueness, and differences are evident between different AM apparatuses. Considerations for design and orientation between different apparatuses should therefore be considered when utilising direct additive manufacturing processes. The areal surface roughness of the marginal regions is within acceptable clinical limits for all manufacturing processes and print orientations considered.

CLINICAL SIGNIFICANCE

The materials and apparatuses for additive manufacturing of zirconia crowns are now clinically acceptable from the perspective of the trueness of a final crown for critical functional surfaces and areal surface roughness of the marginal regions.

Next-generation devices to diagnose residuum health of individuals suffering from limb loss: A narrative review of trends, opportunities, and challenges

OBJECTIVES

There is a need for diagnostic devices that can assist prosthetic care providers to better assess and maintain residuum health of individuals suffering from neuromusculoskeletal dysfunctions associated with limb loss. This paper outlines the trends, opportunities, and challenges that will facilitate the development of next-generation diagnostic devices.

DESIGN

Narrative literature review.

METHODS

Information about technologies suitable for integration into next-generation diagnostic devices was extracted from 41 references. We considered the invasiveness, comprehensiveness, and practicality of each technology subjectively.

RESULTS

This review highlighted a trend toward future diagnostic devices of neuromusculoskeletal dysfunctions of the residuum capable to support evidence-based patient-specific prosthetic care, patient empowerment, and the development of bionic solutions. This device should positively disrupt the organization healthcare by enabling cost-utility analyses (e.g., fee-for-device business models) and addressing healthcare gaps due to labor shortages. There are opportunities to develop wireless, wearable and noninvasive diagnostic devices integrating wireless biosensors to measure change in mechanical constraints and topography of residuum tissues during real-life conditions as well as computational modeling using medical imaging and finite element analysis (e.g., digital twin). Developing the next-generation diagnostic devices will require to overcome critical barriers associated with the design (e.g., gaps between technology readiness levels of essential parts), clinical roll-out (e.g., identification of primary users), and commercialization (e.g., limited interest from investors).

CONCLUSIONS

We anticipate that next-generation diagnostic devices will contribute to prosthetic care innovations that will safely increase mobility, thereby improving the quality of life of the growing global population of individuals suffering from limb loss.