Intra-oral Digital Evaluation of Fit Accuracy for Removable Partial Denture Frameworks Fabricated by Selective Laser Melting Using 2 Different Impression Techniques. Within Subjected Study

Purpose:Within subject study aim to compare the overall accuracy and fit of different components for mandibular metallic removable partial denture (RPD) frameworks fabricated by selective laser melting using combined analog-digital, and fully digital impression techniques.

Material and methods. Two RPD frameworks were fabricated for each of the 24 participants using each of the 2 techniques of the 24 participants enrolled, were of mandibular Kennedy class I, the first technique was the combined analog-digital workflow had the analog steps include: a physical impression was made using polyvinyl siloxane, stone casts were made, then the stone cast was scanned with a laboratory scanner to generate a digital cast. The 3Shape CAD software was then used to design a digital RPD, which was fabricated from a cobalt-chroumum alloy by selective laser melting. The second technique was fully digital where an intraoral digital scanner was used to make a definitive scan, which was sent to the 3Shape software for digitally designing the RPD framework and subsequent selective laser melting for fabrication. For both frameworks in the same participant, the same design was used for consistency. To assess the accuracy of fit, based on STL data analysis (intra-oral digital superimposition evaluation), a color map was constructed using non metrology software, and overall fit accuracy and the misfit (distance between each framework component and the reference intra-oral scan) were measured at rest, guiding plane and lingual plate areas.