Abstract
This study aimed to compare the surface roughness, hardness, and flexure strength of interim indirect resin restorations fabricated with CAD-CAM (CC), 3D printing (3D), and conventional techniques (CV). Twenty disk (3 mm × Ø10 mm) and ten bar specimens (25 × 2 × 2 mm) were fabricated for the CC, 3D, and CV groups, to be used for surface roughness, micro-hardness, and flexural strength testing using standardized protocol. Three indentations for Vickers micro-hardness (VHN) were performed on each disk and an average was identified for each specimen. Surface micro-roughness (Ra) was calculated in micrometers (μm) using a 3D optical non-contact surface microscope. A three-point bending test with a universal testing machine was utilized for assessing flexural strength. The load was applied at a crosshead speed of 3 mm/min over a distance of 25 mm until fracture. Means and standard deviations were compared using ANOVA and post hoc Tukey–Kramer tests, and a p-value of ≤0.05 was considered statistically significant. Ra was significantly different among the study groups (p < 0.05). Surface roughness among the CC and CV groups was statistically comparable (p > 0.05). However, 3D showed significantly higher Ra compared to CC and CV samples (p < 0.05). Micro-hardness was significantly higher in 3D samples (p < 0.05) compared to CC and CV specimens. In addition, CC and CV showed comparable micro-hardness (p > 0.05). A significant difference in flexural strength was observed among the study groups (p < 0.05). CC and 3D showed comparable strength outcomes (p > 0.05), although CV specimens showed significantly lower (p < 0.05) strength compared to CC and 3D samples. The 3D-printed provisional restorative resins showed flexural strength and micro-hardness comparable to CAD-CAM fabricated specimens, and surface micro-roughness for printed specimens was considerably higher compared to CAD-CAM and conventional fabrication techniques.
Highlights
Interim restorations are critical for the successful management of prosthodontic rehabilitation of natural teeth and dental implants
Reported that printed restorations had a micro-hardness value superior to conventional ones. These findings indicate that the existing data on the properties of 3D-printed specimen (3D) printing are limited and controversial
This study assessed surface roughness, micro-hardness, and flexural strength of interim restoration material samples fabricated with CAD-CAM (CC), 3D printing (3D), and conventional method (CV)
Summary
Interim restorations are critical for the successful management of prosthodontic rehabilitation of natural teeth and dental implants. The term interim means for the time being, pending a definitive arrangement, but this does not imply an expected short-term use. Sometimes, they have to function for extended periods during occlusal equilibration, establishment of occlusal vertical dimension, gingival contour formation around implants, and re-establishment of soft tissues after surgical periodontics. They have to function for extended periods during occlusal equilibration, establishment of occlusal vertical dimension, gingival contour formation around implants, and re-establishment of soft tissues after surgical periodontics In all these scenarios, the interim restorations can be extremely crucial as they allow the patient to evaluate comfort, function, and appearance prior to the placement of the definitive restorations. Interim restorations must provide pulpal and periodontal protection, esthetic and occlusal stability, marginal integrity, and resistance to functional loads for prosthodontic rehabilitations with long-term clinical success [1,2,3].
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