Faculty Collaboration Database

Analysis of flexural strength and contact pressure after simulated chairside adjustment of pressed lithium disilicate glass-ceramic. J Prosthet Dent 2018 Sep;120(3):439-446

Date

05/05/2018

Pubmed ID

29724557

DOI

10.1016/j.prosdent.2017.12.025

Scopus ID

2-s2.0-85046346473 (requires institutional sign-in at Scopus site)   3 Citations

Abstract

STATEMENT OF PROBLEM: Research evaluating load-to-failure of pressed lithium disilicate glass-ceramic (LDGC) with a clinically validated test after adjustment and repair procedures is scarce.

PURPOSE: The purpose of this in vitro study was to investigate the effect of the simulated chairside adjustment of the intaglio surface of monolithic pressed LDGC and procedures intended to repair damage.

MATERIAL AND METHODS: A total of 423 IPS e.max Press (Ivoclar Vivadent AG) disks (15 mm diameter, 1 mm height) were used in the study. The material was tested by using an equibiaxial loading arrangement (n≥30/group) and a contact pressure test (n≥20/group). Specimens were assigned to 1 of 14 groups. One-half was assigned to the equibiaxial load test and the other half underwent contact pressure testing. Testing was performed in 2 parts, before glazing and after glazing. Before-glazing specimens were devested and entered in the test protocol, while after-glazing specimens were devested and glazed before entering the test protocol. Equibiaxial flexure test specimens were placed on a ring-on-ring apparatus and loaded until failure. Contact pressure specimens were cemented to epoxy resin blocks with a resin cement and loaded with a 50-mm diameter hemisphere until failure. Tests were performed on a universal testing machine with a crosshead speed of 0.5 mm/min. Weibull statistics and likelihood ratio contour plots determined intergroup differences (95% confidence bounds).

RESULTS: Before glazing, the equibiaxial flexural strength test and the Weibull and likelihood ratio contour plots demonstrated a significantly higher failure strength for 1EC (188 MPa) than that of the damaged and/or repaired groups. Glazing following diamond-adjustment (1EGG) was the most beneficial post-damage procedure (176 MPa). Regarding the contact pressure test, the Weibull and likelihood ratio contour plots revealed no significant difference between the 1PC (98 MPa) and 1PGG (98 MPa) groups. Diamond-adjustment, without glazing (1EG and 1PG), resulted in the next-to-lowest equibiaxial flexure strength and the lowest contact pressure. After glazing, the strength of all the groups, when subjected to glazing following devesting, increased in comparison with corresponding groups in the before-glazing part of the study.

CONCLUSIONS: A glazing treatment improved the mechanical properties of diamond-adjusted IPS e.max Press disks when evaluated by equibiaxial flexure and contact pressure tests.

Author List

Ramadhan A, Thompson GA, Maroulakos G, Berzins D

Author

David Berzins BS,PhD Graduate Program Director for Dental Biomaterials in the General Dental Sciences/Dental Biomaterials department at Marquette University

MESH terms used to index this publication - Major topics in bold

Ceramics
Compressive Strength
Dental Marginal Adaptation
Dental Porcelain
Dental Prosthesis
Dental Restoration Repair
Dental Restoration, Permanent
Humans
In Vitro Techniques