Post-fatigue fracture resistance of premolar teeth restored with endocrowns: An in vitro investigation

Layla Hassouneh; Ahmad A Jum'ah; Marco Ferrari; David J Wood

doi:10.1016/j.jdent.2020.103426

Post-fatigue fracture resistance of premolar teeth restored with endocrowns: An in vitro investigation

J Dent. 2020 Sep:100:103426. doi: 10.1016/j.jdent.2020.103426. Epub 2020 Jul 3.

Authors

Layla Hassouneh¹, Ahmad A Jum'ah², Marco Ferrari³, David J Wood⁴

Affiliations

¹ University of Leeds, School of Dentistry, Division of Restorative Dentistry, Leeds LS2 9JT, United Kingdom.
² Jordan University of Science and Technology, Faculty of Dentistry, Department of Conservative Dentistry, P.O Box 3030, Irbid 22110, Jordan. Electronic address: aajuma@just.edu.jo.
³ University of Leeds, School of Dentistry, Division of Restorative Dentistry, Leeds LS2 9JT, United Kingdom; University of Siena, Department of Medical Biotechnologies, Division of Fixed Prosthodontics, Siena, Italy.
⁴ University of Leeds, School of Dentistry, Division of Oral Biology, Leeds LS2 9JT, United Kingdom.

PMID: 32628987
DOI: 10.1016/j.jdent.2020.103426

Abstract

Objectives: To evaluate the post-fatigue load-to-failure and failure modes of endodontically treated premolar teeth restored with endocrowns fabricated from different CAD/CAM materials.

Materials and methods: A total of 60 extracted human, single-rooted premolar teeth were endodontically treated and sectioned horizontally 2 mm above the cementoenamel junction. Sectioned teeth were restored using two reconstruction designs: endocrowns (C_endo) or post-crowns (C_post) (n = 30 p/g). In each group, reconstructions were fabricated from 3 different CAD/CAM substrates (n = 10 p/g); a resin-based composite (Cera), a lithium disilicate glass ceramic (LiSi) and a monolithic, translucent zirconia (Zir). Additional 10 intact teeth were used as control. Restored teeth were subjected to dynamic fatigue test (10-50 N, 600,000 cycles) and thermocycling (5-55 °C, 1500 cycles). Load-to-failure and failure mode was determined following application of a static, 45° oblique compressive load on each specimen. One-way and Two-way analysis of variance (ANOVA), Tukey's post hoc and chi-square tests were used to determine statistically significant interactions among experimental and control groups.

Results: All specimens survived the mechanical and thermal fatigue tests. A statistically significant interaction between reconstruction design and material type was observed (p < 0.001). C_postZir and C_endoCera groups exhibited significantly higher post-fatigue load-to-failure when compared to other materials of the same reconstruction design (p ≤ 0.001). The highest frequency of catastrophic failures was observed with Zir reconstructions in both designs. Intact teeth exhibited significantly higher load-to-failure when compared to all groups (p ≤ 0.042) except C_postZir (p = 0.345).

Conclusion: Single piece, CAD/CAM resin composite endocrowns can present a reliable option for restoring endodontically treated premolar teeth.

Clinical significance: Endocrowns can be as effective as post-crowns provided appropriate preparation; material selection; and bonding protocols are utilized. Clinicians need to be cautious when prescribing zirconia endocrowns to restore premolar teeth owing to the low fracture resistance and high risk of catastrophic failures.

Keywords: CAD/CAM; Endocrowns; Endodontic treatment; Fracture resistance; Lithium disilicate; Post-crowns; Resin based composite; Zirconia.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Bicuspid
Ceramics
Computer-Aided Design
Crowns
Dental Porcelain*
Dental Restoration Failure
Dental Stress Analysis
Fractures, Stress*
Humans
Materials Testing

Substances

Dental Porcelain