Paulo Francisco Cesar1, Alvaro Della Bona2, Susanne S Scherrer3, Michael Tholey4, Richard van Noort5, Alessandro Vichi6, Robert Kelly7, Ulrich Lohbauer8. 1. Department of Biomaterials and Oral Biology, School of Dentistry, University of São Paulo, São Paulo, Brazil. Electronic address: paulofc@usp.br. 2. Post-Graduate Program in Dentistry, Dental School, University of Passo Fundo, Passo Fundo, Brazil. Electronic address: dbona@upf.br. 3. Division of Fixed Prosthodontics and Biomaterials, University Clinic of Dental Medicine, University of Geneva, Geneva, Switzerland. Electronic address: Susanne.Scherrer@unige.ch. 4. Research and Development Department VITA Zahnfabrik, Bad Saeckingen, Germany. Electronic address: M.Tholey@vita-zahnfabrik.com. 5. School of Clinical Dentistry, University of Sheffield, Sheffield, UK. Electronic address: r.vannoort@sheffield.ac.uk. 6. Department of Medical Biotechnologies, University of Siena, Siena, Italy. Electronic address: alessandrovichi1@gmail.com. 7. Department of Reconstructive Dentistry and Center for Biomaterials, University of Connecticut Health Center, Farmington, USA. Electronic address: kelly@uchc.edu. 8. Research Laboratory for Dental Biomaterials, Dental Clinic 1, University of Erlangen-Nuernberg, Erlangen, Germany. Electronic address: ulrich.lohbauer@fau.de.
Abstract
OBJECTIVES: The objective is within the scope of the Academy of Dental Materials Guidance Project, which is to provide dental materials researchers with a critical analysis of fracture toughness (FT) tests such that the assessment of the FT of dental ceramics is conducted in a reliable, repeatable and reproducible way. METHODS: Fracture mechanics theory and FT methodologies were critically reviewed to introduce basic fracture principles and determine the main advantages and disadvantages of existing FT methods from the standpoint of the dental researcher. RESULTS: The recommended methods for FT determination of dental ceramics were the Single Edge "V" Notch Beam (SEVNB), Single Edge Precracked Beam (SEPB), Chevron Notch Beam (CNB), and Surface Crack in Flexure (SCF). SEVNB's main advantage is the ease of producing the notch via a cutting disk, SEPB allows for production of an atomically sharp crack generated by a specific precracking device, CNB is technically difficult, but based on solid fracture mechanics solutions, and SCF involves fracture from a clinically sized precrack. The IF test should be avoided due to heavy criticism that has arisen in the engineering field regarding the empirical nature of the calculations used for FT determination. SIGNIFICANCE: Dental researchers interested in FT measurement of dental ceramics should start with a broad review of fracture mechanics theory to understand the underlying principles involved in fast fracture of ceramics. The choice of FT methodology should be based on the pros and cons of each test, as described in this literature review.
OBJECTIVES: The objective is within the scope of the Academy of Dental Materials Guidance Project, which is to provide dental materials researchers with a critical analysis of fracture toughness (FT) tests such that the assessment of the FT of dental ceramics is conducted in a reliable, repeatable and reproducible way. METHODS:Fracture mechanics theory and FT methodologies were critically reviewed to introduce basic fracture principles and determine the main advantages and disadvantages of existing FT methods from the standpoint of the dental researcher. RESULTS: The recommended methods for FT determination of dental ceramics were the Single Edge "V" Notch Beam (SEVNB), Single Edge Precracked Beam (SEPB), Chevron Notch Beam (CNB), and Surface Crack in Flexure (SCF). SEVNB's main advantage is the ease of producing the notch via a cutting disk, SEPB allows for production of an atomically sharp crack generated by a specific precracking device, CNB is technically difficult, but based on solid fracture mechanics solutions, and SCF involves fracture from a clinically sized precrack. The IF test should be avoided due to heavy criticism that has arisen in the engineering field regarding the empirical nature of the calculations used for FT determination. SIGNIFICANCE: Dental researchers interested in FT measurement of dental ceramics should start with a broad review of fracture mechanics theory to understand the underlying principles involved in fast fracture of ceramics. The choice of FT methodology should be based on the pros and cons of each test, as described in this literature review.
Authors: Sundus Iftikhar; Noureen Jahanzeb; Mehvish Saleem; Shafiq Ur Rehman; Jukka Pekka Matinlinna; Abdul Samad Khan Journal: Saudi Dent J Date: 2021-01-14