Edge chipping damage in lithium silicate glass-ceramics induced by conventional and ultrasonic vibration-assisted diamond machining

Afifah Z Juri; Renan Belli; Ulrich Lohbauer; Heike Ebendorff-Heidepriem; Ling Yin

doi:10.1016/j.dental.2023.04.001

Edge chipping damage in lithium silicate glass-ceramics induced by conventional and ultrasonic vibration-assisted diamond machining

Dent Mater. 2023 Jun;39(6):557-567. doi: 10.1016/j.dental.2023.04.001. Epub 2023 Apr 18.

Authors

Afifah Z Juri¹, Renan Belli², Ulrich Lohbauer², Heike Ebendorff-Heidepriem³, Ling Yin⁴

Affiliations

¹ School of Electrical and Mechanical Engineering, The University of Adelaide, Adelaide 5005, SA, Australia. Electronic address: afifah.juri@adelaide.edu.au.
² Research Laboratory for Dental Biomaterials, Dental Clinic 1 - Operative Dentistry and Periodontology, University of Erlangen-Nuremberg, Erlangen, Germany.
³ Institute for Photonics and Advanced Sensing (IPAS) and School of Physics, Chemistry and Earth Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia.
⁴ School of Electrical and Mechanical Engineering, The University of Adelaide, Adelaide 5005, SA, Australia. Electronic address: ling.yin@adelaide.edu.au.

PMID: 37076403
DOI: 10.1016/j.dental.2023.04.001

Abstract

Objectives: Diamond machining of lithium silicate glass-ceramics (LS) induces extensive edge chipping damage, detrimentally affecting LS restoration functionality and long-term performance. This study approached novel ultrasonic vibration-assisted machining of pre-crystallized and crystallized LS materials to investigate induced edge chipping damage in comparison with conventional machining.

Methods: The vibration-assisted diamond machining was conducted using a five-axis ultrasonic high-speed grinding/machining machine at different vibration amplitudes while conventional machining was performed using the same machine without vibration assistance. LS microstructural characterization and phase development were performed using scanning electron microscopy (SEM) and x-ray diffraction (XRD) techniques. Machining-induced edge chipping depths, areas and morphology were also characterized using the SEM and Java-based imaging software.

Results: All machining-induced edge chipping damages resulted from brittle fractures. The damage scales, however, depended on the material microstructures; mechanical properties associated with the fracture toughness, critical strain energy release rates, brittleness indices, and machinability indices; and ultrasonic vibration amplitudes. Pre-crystallized LS with more glass matrix and lithium metasilicate crystals yielded respective 1.8 and 1.6 times greater damage depths and specific damage areas than crystallized LS with less glass matrix and tri-crystal phases in conventional machining. Ultrasonic machining at optimized amplitudes diminished such damages by over 50 % in pre-crystallized LS and up to 13 % in crystallized LS.

Significance: This research highlights that ultrasonic vibration assistance at optimized conditions may advance current dental CAD/CAM machining techniques by significant suppression of edge chipping damage in pre-crystallized LS.

Keywords: Diamond machining; Edge chipping damage; Lithium silicate glass-ceramics; Microstructure; Ultrasonic vibration assistance.

Publication types

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

MeSH terms

Ceramics / chemistry
Dental Porcelain* / chemistry
Diamond
Lithium*
Materials Testing
Silicates
Surface Properties
Ultrasonic Waves

Substances

Dental Porcelain
Lithium
Diamond
Silicates