Evaluation of marginal and internal gap of three-unit metal framework according to subtractive manufacturing and additive manufacturing of CAD/CAM systems

Dong Yeon Kim, Eo Bin Kim, Hae-Young Kim, Ji Hwan Kim, Woong Chul Kim

Research output: Contribution to journalArticle

3 Citations (Scopus)


PURPOSE. To evaluate the fit of a three-unit metal framework of fixed dental prostheses made by subtractive and additive manufacturing. MATERIALS AND METHODS. One master model of metal was fabricated. Twenty silicone impressions were made on the master die, working die of 10 poured with Type 4 stone, and working die of 10 made of scannable stone. Ten three-unit wax frameworks were fabricated by wax-up from Type IV working die. Stereolithography files of 10 three-unit frameworks were obtained using a model scanner and threedimensional design software on a scannable working die. The three-unit wax framework was fabricated using subtractive manufacturing (SM) by applying the prepared stereolithography file, and the resin framework was fabricated by additive manufacturing (AM); both used metal alloy castings for metal frameworks. Marginal and internal gap were measured using silicone replica technique and digital microscope. Measurement data were analyzed by Kruskal-Wallis H test and Mann-Whitney U-test (a=.05). RESULTS. The lowest and highest gaps between premolar and molar margins were in the SM group and the AM group, respectively. There was a statistically significant difference in the marginal gap among the 3 groups (P<.001). In the marginal area where pontic was present, the largest gap was 149.39 ± 42.30 μm in the AM group, and the lowest gap was 24.40 ± 11.92 μm in the SM group. CONCLUSION. Three-unit metal frameworks made by subtractive manufacturing are clinically applicable. However, additive manufacturing requires more research to be applied clinically.

Original languageEnglish
Pages (from-to)463-469
Number of pages7
JournalJournal of Advanced Prosthodontics
Issue number6
Publication statusPublished - 2017 Dec 1



  • Internal gap
  • Marginal gap
  • Metal framework
  • Micro-stereolithography

ASJC Scopus subject areas

  • Oral Surgery
  • Dentistry (miscellaneous)

Cite this