Marginal and Internal Fit, Surface Roughness and Fracture Resistance of Hybrid Dental Crown Materials Fabricated With Milling and 3D-Printing Systems: An In Vitro Study.

BACKGROUND

This study evaluated the marginal and internal fit, surface roughness and fracture resistance of three hybrid crown materials fabricated using milling and 3D-printing.

METHODS

A maxillary premolar typodont tooth was prepared and scanned to produce 30 cobalt-chromium dies through selective laser melting 3D printing. Thirty crowns were fabricated from two milled materials (Vita Enamic; Cerasmart) and one printed material (Irix Max) (n = 10). Marginal and internal fit were assessed using a three-dimensional superimposition technique, while surface roughness was measured with an optical profilometer. After cementation, specimens underwent thermocycling for 3600 cycles, followed by 720,000 mechanical loading cycles. Fracture resistance was tested using a universal testing machine and failure modes were recorded. Statistical analysis was performed using one-way ANOVA test.

RESULTS

No statistically significant differences were observed in marginal fit among the groups. Cerasmart showed significantly higher internal gaps but smoother surfaces than Vita Enamic and Irix Max. Vita Enamic exhibited significantly greater fracture resistance compared to Cerasmart. All failures were catastrophic.

CONCLUSION

All crowns exhibited comparable marginal fit. Cerasmart demonstrated smoother surfaces but inferior internal adaptation and fracture strength, whereas Vita Enamic provided superior mechanical performance.