[Fracture toughness of porcelain using indentation method]

Understanding how porcelain resists brittle fracture is crucial for dental applications. Prior research has shown that porcelain is prone to cracking under stress, but the exact resistance levels vary between materials. No prior work had resolved the specific resistance values for multiple commercial porcelains. This gap motivated a study to evaluate fracture toughness using indentation. The study aimed to provide quantitative data for material selection. The need for precise mechanical testing in dental ceramics remains unmet. No prior work had compared a wide range of porcelains using the same method. The lack of standardized fracture toughness data limits clinical decision-making. This paper addresses the need for detailed mechanical characterization.

The purpose of this study was to measure the fracture toughness of nine commercial porcelains using indentation. The focus was on comparing their resistance to brittle fracture. The motivation came from the need to understand material performance in dental restorations. The study aimed to determine if indentation could reliably assess fracture toughness. The researchers wanted to identify the porcelain with the highest resistance. They also sought to categorize materials based on crack propagation patterns. The goal was to provide data for material selection in clinical settings. The study aimed to establish a method for evaluating porcelain durability.

The study used the indentation method to assess fracture toughness. Vickers hardness was measured at a 5kgf load for 15 seconds. Crack lengths and indentation diagonals were recorded for each sample. The c/a ratio was calculated to determine crack propagation. Fractography was used to classify crack patterns as intra- or inter-granular. Statistical analysis compared the KIC values across materials. The study included nine different commercial porcelains. Each porcelain was tested for mechanical resistance to fracture.

The highest Vickers hardness was 1348 for OPT, and the lowest was 666 for CE 8. The indentation diagonal ranged from 42 to 58 microns across materials. Crack lengths varied between 101 and 175 microns. The c/a ratio was between 2.3 and 3.3 for all samples. KIC values ranged from 2.04 to 4.69 MNm-3/2. OPT showed the highest KIC of 4.69 MNm-3/2. VITD had the lowest KIC at 2.04 MNm-3/2. The study found significant differences in fracture resistance among porcelains.

The study found that OPT had the highest fracture toughness among tested porcelains. The indentation method provided reliable KIC values for material comparison. The results suggest that OPT is more resistant to brittle fracture than other materials. Fractography revealed two distinct crack propagation patterns. Intra-granular fractures were observed in AAA, COM, and OPT. Inter-granular fractures were seen in CE 8, VITD, VIT, CE II, UNB, and PEN. The findings support the use of indentation for evaluating porcelain toughness. The study highlights the importance of material selection based on mechanical properties.