The effect of storage time of removable partial denture wax pattern on the accuracy of fit of the cast framework

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.

mentioning

confidence: 99%

“…Many factors, such as the investment material, spruing technique, finishing of the framework, and the type of alloy, could affect the fit of RPD frameworks during the fabrication process. 13 Various methods are used to evaluate RPD framework accuracy of fit. 14 The silicone replica technique has been used in many studies.…”

mentioning

confidence: 99%

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

Negm

Aboutaleb

Alam-Eldein

2019

“…Rantanen and Eerikainen showed that the gap layer of a palatal framework, fabricated by casting, between the framework and master cast was between 0.09 and 0.68 mm . Diwan et al found the width of the gap layer to be between 0.33 and 0.49 mm . Much of the literature during the past 30 years has been based upon expert opinion of the operator or investigator to determine subjective level of fit.…”

mentioning

confidence: 99%

“…5 Diwan et al found the width of the gap layer to be between 0.33 and 0.49 mm. 6 Much of the literature during the past 30 years has been based upon expert opinion of the operator or investigator to determine subjective level of fit. Few articles have quantitatively assessed fit.…”

mentioning

confidence: 99%

Assessing the Accuracy of Casting and Additive Manufacturing Techniques for Fabrication of a Complete Palatal Coverage Metal Framework

Forrester

Sheridan

Phoenix

2019

Purpose To provide information regarding the accuracy of additive manufacturing in comparison to conventional casting, specifically for fabrication of complete palatal coverage metal frameworks. Materials and Methods Three additive manufacturing techniques were tested: selective laser melting (SLM), electron beam melting (EBM), and computer‐aided design/cast (CADcast), with conventional casting as the control. Both the SLM and EBM groups were tested pre‐ and post‐finishing, for a total of six test groups (n = 10/group). A digital master design was used as the standard to which all frameworks were digitally compared by best‐fit analysis, which generated root mean square values using proprietary software. A one‐way ANOVA was conducted to test for statistical differences among materials, followed by a post‐hoc multiple comparison test (Tukey's test HSD). Surface roughness for one framework arbitrarily selected from each group was analyzed using a profilometer. Results There was a significant difference in accuracy among the materials (F = 99.79, p < 0.0001). A post‐hoc Tukey test indicated that CADcast differed significantly from the other five materials (i.e., most accurate, p < 0.01). EBM prefinished and EBM finished were both significantly different from the other materials (i.e., least accurate). Color mapping images help visualize the differences between each framework compared to the master design. The surface roughness values ranged from 22 to 63.5 µm, with CADcast being the smoothest, and EBM prefinished the roughest. Conclusions CADcast and SLM techniques were as or more accurate than the conventional technique for producing an uncomplicated framework design. Further investigation is recommended regarding the surface roughness of additive manufacturing products and potential biological complications.

“…Some studies reveal that the accuracy of fit of the major connector could be affected by the time and temperature of storage, and the liquid melting range of the wax pattern 9,10 . The distortion of major connector frameworks could be due to the shrinkage of pattern wax.…”

mentioning

confidence: 99%

Effect of Anchorage on the Accuracy of Fit in Removable Partial Denture Framework

Gowri

Patil

Nadiger

et al. 2010