In vitro investigations on retention force behavior of conventional and modern double crown systems. Issue 1 (January 2021)

• Record Type: Journal Article
• Authors: Luft, Viktor; Pospiech, Peter; Schurig, Axel; Schmitter, Marc
• Is Part Of: Dental materials. Volume 37:Issue 1(2021)
• Page Start: 191
• Page End: 200
• Publication Date: 2021-01
• Subjects: Double crowns -- Dental casting technique -- CAD/CAM -- Electroforming -- Gold alloys -- CoCr -- Y-TZP -- PEEK; Dentistry -- Periodicals; Dental materials -- Periodicals; 617.695
• DOI: 10.1016/j.dental.2020.10.028
• Languages: English
• ISSNs: 0109-5641

Abstract

Highlights: Conventional and CAD/CAM-fabricated double crowns achieve sufficient retention under artificial aging. The "gold standard" of cast gold alloy provides the most constancy in retention force values over long-term use. CAD/CAM technology generally allows a more predictive setting of retention force and lower retention force losses. Confocal microscopy qualifies for three-dimensional visualizing of wear phenomena. Abstract: Objective: This study aimed to investigate the effects of long-term use on the retention force and wear behavior of double crown systems. Methods: Based on a common double crown design sixty pairs of telescopic crowns were fabricated and divided into six groups, each consisting ten samples: "Gold standard" cast gold alloy primary and secondary crown (GG) and cast non-precious alloy (NN), computer-aided design (CAD)/computer-aided manufacturing (CAM)-milled zirconia primary crown and galvanoformed secondary crown (ZG), CAD/CAM-milled non-precious alloy primary and secondary crown (CC NN), CAD/CAM-milled zirconia primary crown and non-precious alloy secondary crown (CC ZN) and CAD/CAM-milled zirconia primary crown and polyetheretherketone (PEEK) secondary crown (CC ZP). In the constant presence of artificial saliva, all samples were subjected to 10, 000 joining-separation cycles at a velocity of 120 mm/min. Wear was analyzed by reflected light microscopy and confocal microscopy before and after artificial aging. Results: Retention force losses were observed in each group after long-term use, with significant losses in the groups ZG and CC ZP (pZG = 0.01, pCC ZP = 0.049). During artificial aging, no significant differences in pull-off force were recorded for groups GG, NN and CC ZN. Regarding wear, merely the Y-TZP primary crowns of the CC ZP group displayed no surface changes. Significance: All tested production methods and material combinations seem to be suitable for clinical practice. CAD/CAM technology allows similarly predictable results to be achieved as the gold standard. Confocal microscopy is recommended for surface examinations of double crowns.