Mechanical properties of printable and machinable denture tooth material
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Abstract
OBJECTIVES: The aim of this study was to compare and determine the mechanical properties of printed and machined provisional and definitive dental restorations. Specimens from various materials were obtained via different production techniques, additive or subtractive manufacture. These samples underwent various tests to examine properties including wear resistance and flexural strength.
METHODOLOGY: Five different materials were tested for wear resistance and flexural strength via three distinct procedures. The materials were from the following manufacturers: PAC-DENT (definitive printed material), BEGO (provisional printed material), DENTCA (provisional printed material), SHOFU (definitive machined material), and TELIO (provisional machined material). The specimens for each material were divided into subgroups of 12 specimens per test and prepared into specific dimensions in accordance with the parameters of the test. The first procedure was a wear test that examined a 3.5 mm in diameter pin-shaped specimen sliding on a ceramic substrate. The second test was a biaxial flexural strength test that examined disc-shaped specimens using a ball-on-three-ball fixture. The third test was a three-point bend flexural strength test that examined two different-sized rectangular bar specimens. The final test was a Vickers microhardness test that examined indentations made along the surfaces of the specimens. Sites of fracture, deformation, or wear were examined under scanning electron microscope (SEM). Results were analyzed via ANOVA, Tukey’s HSD test, and student t-test (α = 0.05).
RESULTS: The results of the wear test indicated that SHOFU and TELIO had a significantly greater rate of volume loss than the remaining materials. The results of the biaxial flexural strength test indicated that the TELIO group was significantly higher than the other materials with a mean value of 187.63 MPa. The three-point bend test on materials tested on a 10 mm support span indicated that the TELIO group once again showed significantly higher values than the remainders with a mean flexural strength of 149.80 MPa. However, on the 20 mm support span of the three-point bend test, PAC-DENT showed significantly higher flexural strength values of 140.47 MPa. SHOFU showed the highest mean hardness value of 71.60 Hv, which was significantly higher than other materials. SEM imaging and EDS analysis showed the existence of inorganic filler load in the SHOFU, PAC-DENT, and BEGO materials.
CONCLUSION: The results of the study rejected the proposed null hypothesis. The type and production method of a restorative material did indeed influence the resulting mechanical properties. The properties of wear resistance, flexural strength, and surface hardness that were tested all exhibited significant differences between the materials. Although differences were found between the individual materials themselves; when compared to the existing literature, it was found that the resulting mechanical properties values all fell within an acceptable range when compared to most commercially available products. This was crucial information, as it indicated that these materials would be practical and of use in a clinical setting. Further investigation is required for other factors which may affect the aforementioned mechanical properties, such as aging and fatiguing, which were not studied in this thesis.