Evaluation of Marginal Accuracy of PEEK Vs. Lithium Disilicate Single Crowns Constructed By Two Fabrication Techniques: CAD/CAM And Heat Press (In-Vitro Study)

Abstract

Background: Metal-ceramic restorations were considered the gold standard, however, all-ceramic restorations gained popularity owing to their remarkable properties. Purpose: To evaluate the marginal accuracy of IPS e.max and PEEK Bio.HPP monolithic crowns constructed by two fabrication techniques (Heat Press and CAD/CAM). Materials and methods: Twenty monolithic crowns were divided into two equal groups according to the materials used. Group E: Lithium disilicate crowns and Group P: PEEK BioHPP crowns. Each group was further subdivided into two equal subgroups according to the fabrication technique with five crowns per subgroup (n=5). Subgroup H: Heat Press technique and Subgroup C: CAD/CAM technique. A biogeneric copy STL file was generated biogeneric and sent to a 5-axis CAM machine to mill identical IPS e.max, PEEK BioHPP, and wax patterns. IPS e.max and PEEK Bio.HPP crowns were then heat-pressed using the milled wax patterns. The vertical marginal gap (VMG) distance was evaluated for each crown surface at five predetermined equally distributed points using the direct view technique. Results: There was no statistically significant difference in the VMG distance between IPS e.max (23.1±2.8μm) and PEEK Bio.HPP (24.4±1.6μm) crowns. Crowns heat-pressed from IPS e.max ingots (23.1±2.8μm) and PEEK Bio.HPP pellets (24.4±1.6μm) showed a lower statistically significant mean VMG distance than the crowns CAD/CAM milled from IPS e.max blocks (29.5±3.2μm) and PEEK Bio.HPP blanks (30.2±1.4μm). Conclusion: IPS e.max and PEEK crowns fabricated using either technique showed clinically acceptable results, meanwhile the heat-pressing technique showed better marginal adaptation when compared to milled crowns.