Comparison of margin discrepancy of complete gold crowns fabricated using printed, milled, and conventional hand-waxed patterns.

Statement Of Problem: The recent application of printing for the fabrication of dental restorations has not been compared and evaluated for margin discrepancy (margin fit) with restorations fabricated using milling and conventional hand-waxing techniques.

Purpose: The purpose of this in vitro study was to evaluate and compare margin discrepancy of complete gold crowns (CGCs) fabricated from printed, milled, and conventional hand-waxed patterns.

Material And Methods: Thirty crown patterns were produced by each of 3 different methods: printed by ProJet DP 3000, milled by LAVA CNC 500, and hand waxed, then invested and cast into CGCs. Each crown was evaluated at 10 positions around the margin on the corresponding epoxy die under ×50 light microscopy to determine the mean and maximum margin discrepancy. Measurements were made using a micrometer positioning stage. The results were compared by ANOVA (α=.05).

Results: Milled and hand-waxed patterns were not statistically different from each other (P>.05), while printed patterns produced significantly higher mean and maximum margin discrepancy than milled and hand-waxed patterns (P<.05).

Conclusions: Relative to margin discrepancy, the LAVA CNC 500 milled and hand-waxed patterns were not significantly different from each other. The ProJet DP 3000 printed patterns were significantly different from LAVA CNC 500 milled and hand-waxed patterns, with an overall poorer result. Fabricating CGCs from printed patterns produced a significantly higher number of crowns with unacceptable margin discrepancy (>120 μm).