Details

Autor(en) / Beteiligte

• Jodha, Kartikeya Singh

Titel

Fractal Analysis of Dental Ceramics Using a Novel Unbiased Method

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

2021

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• The fracture surfaces of ceramic prostheses can be characterized using fractal geometry to provide a wealth of information about the material properties and the conditions present at the time of failure. Previous studies had developed an unbiased factor to measure the fractal dimension of the fracture surface accurately and later analyzed two benchmark materials (silica glass and silicon nitride) using the same technique. We analyzed two glass-ceramics (lithium disilicate and nanofluorapatite) and a polycrystalline ceramic (3Y-TZP) to validate the unbiased method. The fracture toughness was calculated using various techniques, and the fracture surface was analyzed to calculate the fractal dimension. The nanofluorapatite glass-ceramic followed the previous relationship between the fracture toughness and square root of fractal dimensional increment. The lithium disilicate and 3Y-TZP deviated from the glasses and polycrystalline models, respectively, due to toughening mechanisms. A combination of the two glass-ceramics was used to create a bilayered specimen to analyze the fractal dimension values in the different layers after the crack propagates through both layers. The fractal dimension values in the two layers were different, but were similar to those observed when the two materials were tested in monolithic conditions. Fractographic analysis showed crack arrest at the interface that resulted in different tortuosity in the different layers. The mirror, mist, and hackle regions of the lithium disilicate glass-ceramic fracture surface were analyzed to compare the fractal dimension values. No significant difference between the fractal dimension values from the different regions was observed. Any region of the primary fracture surface of lithium disilicate glass-ceramic can be used to calculate the fractal dimension. Different regions on fracture surfaces of clinically failed zirconia implants were analyzed, and they yielded similar fractal dimension values. The resulting information will have a high potential impact on the field of prosthodontics. It may also apply to ceramic components used in orthopedic surgery and the automotive, aerospace, and semiconductor industries.