Virtual Evaluation of the Accuracy of Fit and Trueness in Maxillary Poly(etheretherketone) Removable Partial Denture Frameworks Fabricated by Direct and Indirect CAD/CAM Techniques

Abstract

Purpose To compare the accuracy of fit and trueness of maxillary poly(etheretherketone) (PEEK) removable partial denture (RPD) frameworks fabricated by direct and indirect computer‐aided design/computer‐aided manufacturing (CAD/CAM) techniques. Materials and Methods A definitive maxillary class I master epoxy model was duplicated to create a stone cast. The cast was scanned, and an RPD was designed. Standard tessellation language (STL) data were used to fabricate 20 identical RPD frameworks using two CAD/CAM techniques: direct milling of PEEK and indirect additive manufacturing (resin printing combined with PEEK thermopressing using the lost‐wax technique). All the frameworks for each technique (n = 10) and the reference cast were scanned. To assess the accuracy of fit, a color map was constructed using metrology software, and the misfit (distance between each framework and the reference cast) was measured at 25 standardized points. To assess the overall trueness, each framework STL file was superimposed over the original design's STL file, and the average deviation was recorded in microns. Data were statistically analyzed using t‐test. Results Color mapping showed distinct pressure areas in the anterior and posterior straps of the major connector in the indirect technique, while a more uniform distribution of the color map was observed in the direct technique. A significant difference was found between the two techniques regarding the overall accuracy of fit. Compared with the indirect technique, the milled frameworks showed significantly better overall trueness (p < 0.001). Conclusions Although a significant difference in the overall fit accuracy was noted between both techniques, the fit was an acceptable clinical fit. The fabrication method affects the fit in the anterior and posterior strap areas. The frameworks of the direct technique revealed better overall trueness values compared with the indirect technique.

Materials in digital dentistry—A review

“…Accuracy of fit of removable partial dentures fabricated by conventional techniques and CAD/CAM PEEK dentures have been compared with the latter resulting in comparable, and in some instances, a more superior fit to conventional techniques. 21,22 Moreover, two-body wear test of PEEK was more favorable compared to the other CAD/CAM composite resin and PMMA material. 23 in vitro testing of PEEK molar crowns fabricated on zirconia and titanium abutments in a chewing simulator resulted in acceptable fracture strength property, recommending them for clinical application.…”

“…Postprocessing of these materials is mechanically stable, more easily milled than metals, and are therefore friendlier to the milling machines. Accuracy of fit of removable partial dentures fabricated by conventional techniques and CAD/CAM PEEK dentures have been compared with the latter resulting in comparable, and in some instances, a more superior fit to conventional techniques . Moreover, two‐body wear test of PEEK was more favorable compared to the other CAD/CAM composite resin and PMMA material .…”

“…Clinical trials are still lacking for these ceramics to consider as a viable option for indirect restorations. Various properties, preparation requirements, and compositions of resin‐based ceramics can be found in Table …”

The use of PEEK in digital prosthodontics: A narrative review

“…CAD-CAM PEEK RDP frameworks can be fabricated by several methods such as direct milling of PEEK blanks or 3D printing of a resin/wax pattern framework which is then thermo-pressed using the conventional lost-wax/resin technique [41]. Clinically acceptable fit values were found for both techniques but directly milled PEEK frameworks had higher fit and trueness values than indirectly fabricated frameworks.…”

<p>A Scoping Review on the Accuracy of Fit of Removable Partial Dentures in a Developing Digital Context</p>

“…Negm et al (2019) used metrology software for the color map technique and the misfit (distance between each framework and the reference cast) was measured at 25 standardized points. 38 In order to assess the overall accuracy, each STL file of the framework was superimposed over the original STL file of the design, and the average deviation was recorded in microns. 38 In addition, a study by Soltanzadeh et al (2019) used the same software to measure the gap distance between the frameworks and scanned master model at 8 locations.…”