Evaluation of color stability and bond strength of interim restorations fabricated by CAD/CAM and 3D printing: an in vitro study
摘要
Mechanical properties of interim restorations, as well as fabrication methods, are important for the integrity of restorations, especially for a long interim period. Interim restorations are subjected to occlusal loads; therefore, an adequate bond strength should be maintained until the final restoration is delivered. Color stability is also crucial in the esthetic zone throughout the long-term treatment phase. Therefore, both color stability and bond strength are dependent on the fabrication methods.
Aim of Studyto evaluate the color stability and bond strength of 3-D printed and CAD/CAM milled interim restorations, and to compare between different groups regarding their color stability and bond strength.
Materials and methodsA total of 72 interim PMMA specimens were fabricated in two distinct shapes: disc-shaped (8 mm in diameter × 2 mm in height) and square-shaped (10 mm × 10 mm × 2 mm thick). Half of the specimens (n = 36) were manufactured using CAD/CAM milling, while the remaining half (n = 36) were produced through 3D printing. Within each fabrication method, the specimens were categorized into two subgroups: Subgroup A, which consisted of 12 square-shaped specimens designated for color stability testing, and Subgroup B, comprising 24 disc-shaped specimens intended for shear bond strength testing. In Subgroup B, the discs were further divided based on surface treatment into three groups: surface roughening with a bur (n = 8), sandblasting (n = 8), and an untreated control group (n = 8). Color stability and bond strength measurements were recorded for all relevant specimens.
ResultsIn both CAD/CAM milled and 3D printed groups, there was a significant difference in the color stability of the specimens over time (p < 0.05). They had high discoloration values with CAD/CAM specimens, with a mean of 13.50 (0.10), while 3D printed specimens had a mean of 14.31(0.10). Shear bond strength was also significantly different between the experimental groups with CAD/CAM milled specimens: the control group, 0.53 ± 0.33; the sandblasted group, 1.16 ± 0.25; and the roughened group, 1.00 ± 0.34. In contrast, the 3D printed specimens showed the following results: Control, 1.63 ± 0.90; Sandblasted, 1.44 ± 0.42; and roughened, 1.30 ± 0.43.
ConclusionCAD/CAM milled PMMA exhibited higher color stability compared to 3D printed PMMA, with coffee having a higher staining potential on PMMA than tea beverages. CAD/CAM shear bond strength was higher with surface treatment by aluminum oxide particles, while 3D printed PMMA has a higher shear bond without any surface treatment.