scholarly journals Polyoxymethylene as Material for Removable Partial Dentures—A Literature Review and Illustrating Case Report

2021 ◽  
Vol 10 (7) ◽  
pp. 1458
Author(s):  
Oliver Schierz ◽  
Leonie Schmohl ◽  
Sebastian Hahnel ◽  
Angelika Rauch

Compared to thermoplastic manufacturing techniques, computer-aided design (CAD) and computer-aided manufacturing (CAM) technologies made it easier to process modern restorative and prosthetic materials with improved material properties. In dentistry, tooth-colored alternatives to metal-based frameworks for application in removable dental prostheses (RDP) emerged. With regard to this aspect, the current article provides an overview of the specific material properties of polyoxymethylene (POM). Furthermore, it reviews scientific literature indexed in PubMed and Web of Science that focuses on RDPs fabricated from POM within the last 10 years. Finally, a prosthetic rehabilitation of a patient with a RDP fabricated from POM is illustrated and observation during a follow-up over 10 months are described. Scientific data and clinical observations indicate that polyoxymethylene is a promising material that bridges gaps in dental therapeutic options. While survival time may be limited due to wear, POM might be a favorable option for application in semi-permanent restorations.

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1401
Author(s):  
Doo-Bin Song ◽  
Man-So Han ◽  
Si-Chul Kim ◽  
Junyong Ahn ◽  
Yong-Woon Im ◽  
...  

This study investigated the fitting accuracy of titanium alloy fixed dental prostheses (FDP) after sequential CAD/CAM (Computer Aided Design/Computer Aided Manufacturing) fabrication. A three-unit FDP model connecting mandibular second premolars and molars was prepared and scanned to fabricate titanium FDPs by CAD/CAM milling. A total of six FDPs were sequentially milled in one titanium alloy disk using a new set of burs every time (n = 4). The fitting accuracy of FDPs was mesiodistally evaluated by a silicone replica technique and the measurement was triplicated at four different locations: MO (marginal opening), MG (marginal gap), AG (axial gap), and OG (occlusal gap). Data were statistically analyzed using ANOVA and Tukey’s HSD test. The fitting accuracy of PMMA (polymethyl methacrylate) FDPs milled using the worn or new bur were evaluated by the same procedure (n = 6). The mean dimensions of titanium FDP for all measuring positions, except for AG, were significantly increased from the third milling. However, no difference was noted between the first FDP and the second FDP milled with the same set of burs. Severe edge chippings were observed in all milling burs. Detrimental effects of the worn burs on the fitting accuracy were demonstrated in the CAD/CAM-milled PMMA FDP. The results recommend proper changing frequency of cutting burs to achieve the quality of fit and predictable outcomes for dental CAD/CAM prostheses.


Author(s):  
L Q Tang ◽  
D N Moreton

The timing scroll is an important feeding mechanism on packaging lines. As packaging line speeds have increased and the shape of containers has become more diverse, the techniques used for the design and manufacture of such timing scrolls have become critical for successful packaging line performance. Since 1980, various techniques have evolved to improve scroll design, manufacture and the associated line performance. In recent years, as CAD (computer aided design), CAM (computer aided manufacture) and CNC (computer numerical control) techniques have evolved, scroll design and manufacturing techniques began to be linked with computer techniques. In this paper, a scroll design and manufacturing package is presented which can be run on a minicomputer, such as a μ-VAX on an IBM PC clone. This scroll package can produce a timing scroll for any type of container with a correct pocket shape and good dynamic characteristic. Tests using carefully chosen containers have been made using this package and the results indicate that the scrolls obtained by this package have the correct pocket shape and good line performance. However, the design of a good pick-up geometry for some container shapes remains a problem.


2020 ◽  
Vol 10 (21) ◽  
pp. 7735
Author(s):  
Hai Yen Mai ◽  
Jae-Min Seo ◽  
Jae-Kwang Jung ◽  
Du-Hyeong Lee

Occlusal contact loss occasionally occurs following the placement of implant-supported fixed dental prostheses in the posterior region. This complication is caused by the change in the vertical dimension of occlusion after the recovery of mastication. The change is probably related to the prosthesis sinking phenomenon and previous mandibular dislocation. The use of interim prostheses could help re-establish the vertical dimension of occlusion. The definitive prostheses can then be accurately fabricated using digital techniques in the newly established vertical dimension. In this case report, we introduce a protocol incorporating a computer-aided design and computer-aided manufacturing (CAD-CAM) interim prosthesis and digital techniques to minimize the occurrence of unexpected initial occlusal changes in the prosthetic treatment of implant-supported prostheses in the posterior region.


Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5588
Author(s):  
Angelika Rauch ◽  
Sebastian Hahnel ◽  
Elena Günther ◽  
Wolfgang Bidmon ◽  
Oliver Schierz

The aim of this study was to compare the clinical properties of tooth-colored computer-aided design/computer-aided manufacturing (CAD/CAM) materials for the fabrication of a 3-unit fixed dental prostheses (FDPs) in the same clinical scenario. A 53-year-old female patient was supplied with a 3-unit FDP to replace a second premolar in the upper jaw. Restorations were fabricated from 3 mol%, 4 mol%, and 5 mol% yttrium oxide zirconia, zirconia with translucency gradient, indirect composite resin, polyetheretherketone (PEEK), and polyetherketoneketone (PEKK). Milling time, weight, and radiopacity were investigated. Esthetics were examined following the US Public Health Service criteria (USPHS). The milling time for zirconia was twice as high as for the indirect composite resin, PEEK, or PEKK. The latter materials had a weight of 2 g each, while zirconia restorations yielded 5 g. Zirconia presented intense radiopacity. PEEK and PEKK required veneering and an opaquer was applied to the PEKK framework. All FDPs showed acceptable esthetics. PEEK and PEKK restorations were featured by a grayish shimmering. A variety of CAD/CAM materials are available to fabricate 3-unit FDPs with esthetically acceptable results. In the esthetic zone, PEEK and PEKK require veneering and an opaquer might be applied. Milling time, weight, and radiopacity were relatively high for zirconia FDPs.


2021 ◽  
Vol 6 (2) ◽  
Author(s):  
Nagy Abdulsamee

Background: Advanced computer-aided design and computer-aided manufacturing (CAD-CAM) technology led to the introduction of an increasing number of machinable materials suitable for dental prostheses. One of these materials is polyetheretherketone (PEEK), a high performance polymer recently used in dentistry with favorable physical, mechanical and chemical properties. Purpose: The aim of this study was to review the current published literature on the use of PEEK for the fabrication of dental prostheses with CAD-CAM techniques. Methods: Electronic database searches were performed using the terms “PEEK”, “CAD-CAM”, “dental”, “dentistry” to identify studies related to the use of PEEK for the fabrication of CAD-CAM prostheses. Results: A great number of in vitro studies are available in the current literature pointing out the noticeable properties of PEEK. The use of PEEK has been recommended for a wide range of CAD-CAM fabricated fixed and removable dental prostheses, occlusal splints, intra-radicular posts, implant abutments, customized healing abutments, space maintainers for pediatric dentistry, orthodontic appliances and provisional restorations. However, only a few clinical studies were identified. Conclusions: PEEK could be considered as a viable alternative for CAD-CAM dental appliances to well-established dental materials. Due to the scarcity of clinical data, clinical trials are needed to assess the longterm performance of PEEK prostheses.


Author(s):  
Roberto Montanini ◽  
Michele Scafidi ◽  
Giorgio Staiti ◽  
Antonia Marcianò ◽  
Leonardo D’Acquisto ◽  
...  

This study aims to compare in-vitro the fitting accuracy of implant-supported metal frameworks used for full-arch orthodontic restoration. The hypotheses tested were as follows: (1) for a fixed implant morphology, strains developed within the framework depend on how the framework had been fabricated and (2) stresses transferred to the implant–bone interface are related to the amount of framework misfit. Metal frameworks were fabricated using four different manufacturing techniques: conventional lost-wax casting, resin cement luting, electrospark erosion, and computer-aided design/computer-aided manufacturing milling. Each framework was instrumented with three strain gauges to measure strains developed because of prosthetic misfit, while quantitative photoelastic analysis was used to assess the effect of misfit at the implant–resin interface. All the tested frameworks presented stress polarization around the fixtures. After screw tightening, significantly greater strains were observed in the lost-wax superstructure, while the lowest strains were observed in the luted framework, demonstrating consistent adaptation and passive fitting. No significant difference in stress distribution and marginal fit was found for bars fabricated by either computer-aided design/computer-aided manufacturing or spark erosion. This study suggested that, in spite of known limitations of in-vitro testing, direct luting of mesostructures and abutments should be the first clinical option for the treatment of complete edentulism, ensuring consistent passive fitting and effective cost–benefit ratio.


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