THE EFFECT OF SPRUE DESIGN ON THE MARGINAL REPRODUCIBILITY OF CAST TITANIUM CROWNS

주입선 형태가 티타늄 주조관의 변연재현성에 미치는 영향

  • Park Jae-Kyoung (Department of Dentistry, Graduate School, Pusan National University) ;
  • Jeong Chang-Mo (Department of Dentistry, Graduate School, Pusan National University) ;
  • Jeon Young-Chan (Department of Dentistry, Graduate School, Pusan National University)
  • 박재경 (부산대학교 치과대학 보철학교실) ;
  • 정창모 (부산대학교 치과대학 보철학교실) ;
  • 전영찬 (부산대학교 치과대학 보철학교실)
  • Published : 2002.08.01

Abstract

There has been a great interest in the use of titanium for fixed and removable prostheses in recent because of its excellent biocompatibility. However the high melting temperature and chemical reactivity of titanium necessitates casting systems different from those used in conventional casting. The current titanium casting systems are based on an electric-arc design for melting the metal in an argon atmosphere and its exclusive investment. Despite the new developments in Ti casting systems, inadequate mold filling and internal porosity are frequently observed casting defects. Therefore, the study on the fabrication technique including sprue design to solve these casting defects is still necessary. In this study to evaluate the effect of sprue design on the castability of simulated cast titanium crowns, 10 cylindrical cast crowns for each group with four different sprue design(Single group. Double group, Runner bar group. Reservoir group) were fabricated. An impression of the entire casting margin was made and cut at $90^{\circ}$ intervals, and the sections were photographed in a microscope at $100{\times}$ magnification to record marginal discrepancy. The internal porosities of the cast crowns were disclosed by radiographs. Within the limits of this study. the following conclusions were drawn. 1. The overall mean marginal discrepancies for each group were as follows: Double group, $43.65{\mu}m$; Reservoir group, $50.27{\mu}m$; Single group, $54.17{\mu}m$; Runner bar group, $58.90{\mu}m$ (p<0.05). 2. The mean of marginal discrepancies for wax patterns was $10.65{\mu}m$. 3 The numbers of internal porosity showed the most in Runner bar group followed by Single group, Reservoir group, and Double group.

Keywords

References

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