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. 2021 Feb;13(1):36-45.
doi: 10.4047/jap.2021.13.1.36. Epub 2021 Feb 23.

Fracture resistance of CAD-CAM all-ceramic surveyed crowns with different occlusal rest seat designs

Saurabh Chaturvedi  1 , Turki Alqahtani  1 , Saleh Alsolami  1 , Abdulbari Alqahtani  1 , Gotam Das  1 , Ebrahim Alsubaiy  1
Affiliations

Fracture resistance of CAD-CAM all-ceramic surveyed crowns with different occlusal rest seat designs

Saurabh Chaturvedi et al. J Adv Prosthodont. 2021 Feb.

Abstract

Purpose: To investigate the fracture resistance of monolithic CAD-CAM all-ceramic surveyed crowns with two different occlusal rest seat designs.

Materials and methods: Two maxillary first premolar were prepared for all-ceramic surveyed crowns with wide (2/3rd of buccolingual width of an unprepared tooth) or narrow (1/3rd of buccolingual width of an unprepared tooth) disto-occlusal rest seat (ORS) designs. Eighty monolithic CAD-CAM all-ceramic surveyed crowns were prepared and divided into 4 groups - Group CR, Composite resin material as a control; Group LDS, Lithium disilicate based material; Group ZIPS, zirconia-material (IPS ZirCAD); and Group ZLHT, zirconia- material (CeramillZolidht+). Crowns were cemented on an epoxy resin die with adhesive resin cement. The fracture resistance of crowns was tested with the universal machine. Univariate regression analysis was used.

Results: The mean ± standard deviation of maximum failure force values varied from 3476.10 ± 285.97 N for the narrow ORS subgroup of group ZIPS to 687.89 ± 167.63 N for the wide ORS subgroup of group CR. The mean ± standard deviation of maximum force was 1075 ± 77.0 N for group CR, 1309.3 ± 283.9 N for group LDS, 3476.1 ± 285.97 N for group ZIPS, and 2666.7 ± 228.21 N for group ZLHT, with narrow occlusal rest seat design. The results of the intergroup comparison showed significant differences in fracture strength with various material groups and occlusal rest seat designs (P <.001).

Conclusion: The zirconia-based all-ceramic surveyed crowns fractured at more than double the load of Lithium disilicate based crowns. The crowns with narrow base occlusal rest seat design had statistically significantly higher fracture resistance than surveyed crowns with wide occlusal rest seat design. The use of narrow occlusal rest seat design in CAD-CAM all ceramic surveyed crowns provides higher fracture resistance, and therefore narrow occlusal rest design can be used for providing esthetics with high strength.

Keywords: CAD-CAM; Digital dentistry; Prosthodontics; Removable prosthodontics.

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Figures

Fig. 1
Fig. 1. Flow chart of study.
Fig. 2
Fig. 2. Representative images of all ceramic surveyed crowns with 2 occlusal rest seat designs. (A) wide occlusal rest seat-WORS; (B) narrow occlusal rest seat-NORS.
Fig. 3
Fig. 3. (A) Specimen in position for compression test in universal testing machine, (B) fractured crown - occlusal view, (C) fractured crown-axial view.
Fig. 4
Fig. 4. Results of fracture strength for various material groups and occlusal rest seat design.
See this image and copyright information in PMC

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