Marginal adaptation of metal copings: selective laser fusion versus casting with a printed pattern
Keywords:
three-dimensional printing; computer-aided design; dental prosthesis; dental alloys; dental technologyAbstract
Introduction: Marginal adaptation of metal copings is critical, as wide gaps favor the dissolution of cement and the retention of biofilm. In clinical practice, digital workflows using selective laser melting and hybrid workflows using printed patterns and casting coexist, which require standardized comparison.
Objective: To evaluate the marginal gap of copings fabricated by CAD/CAM+SLM and by 3D printing of castable pattern followed by casting.
Methods: An in vitro experimental study was conducted with 40 metal copings (20 per technique). With a standardized chamfer finish line, the model was digitized and the copings were designed in CAD. The CAD/CAM+SLM group was fabricated by SLM, and the 3D printing+casting group was produced using resin patterns and induction casting. Marginal gap (µm) was measured by stereomicroscopy at four points (lingual, mesial, vestibular, and distal). GEE was used for repeated measurments, and Fisher’s exact test was used for categorical variables.
Results: CAD/CAM+SLM showed smaller gaps at the four evaluated points (32.63, 39.42, 29.41, and 37.27 µm) compared to 3D printing+casting (98.83, 83.36, 68.41, and 89.92 µm), with significant differences (p<0.001). The mean per coping was 34.66±7.44 µm versus 86.98±19.97 µm (p<0.001). In the categorical analysis, adaptation was higher with CAD/CAM+SLM at the lingual point (100.0% vs. 73.7%; p=0.047).
Conclusions: CAD/CAM+SLM showed better marginal adaptation than 3D printing+casting under in vitro conditions.
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