Comparison of marginal and internal adaptation of provisional polymethyl methacrylate restorations fabricated by two three‑dimensional printers: An in vitro study

Chairside fabrication of provisional restorations using three‑dimensional (3D) printers is rising in digital dentistry. The purpose of this research was to compare the marginal and internal adaptation of provisional polymethyl methacrylate (PMMA) restorations fabricated by two different 3D printers.

In this in vitro investigation, an intact maxillary 1st molar acrylic model was first digitalized by a laboratory scanner. It was then prepared for an all‑ceramic restoration and scanned again by the same scanner. The final restoration was designed in Exocad according to the scan files with a 50 μm cement gap. PMMA restorations were printed by two 3D printers; Group 1: Asiga (n = 10) and Group 2: Digident (n = 10). The replica technique was used to assess the marginal and internal fit of the restorations, and one‑way ANOVA was used to analyze the data. P <0.05 was regarded as statistically significant.

The mean marginal gap of crowns in Group 1 was significantly lower than that of Group 2 (75 vs. 195 μm, P = 0.001). Regarding internal adaptation, no significant difference was found between the axial gap values in both groups (P > 0.05). The mean occluso‑axial gap (90 vs. 140 μm, P = 0.026) and the mean occlusal gap (116 vs. 300 μm, P = 0.001) of crowns in Group 1 were significantly smaller compared to the equivalent values in Group 2.

Provisional PMMA crowns fabricated by the Asiga printer showed significantly higher marginal and internal adaptation than those manufactured by Digident at all points except for the axial surface.