Mold filling of titanium castings using a 45° marginal edge angle

Hiroshi Shimizu, DDS, PhD(a) Kouichi Watanabe, PhD(b) Toru Okabe, PhD(c), and Yutaka Takahashi, DDS, PhD(a)

(a)Division of Removable Prosthodontics, Department of Oral Rehabilitation, Fukuoka Dental College, Fukuoka, Japan, (b)Division of Dental Biomaterials Science, Department of Oral Health Science, Course for Oral Science, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan, and (c)Department of Biomaterials Science, Baylor College of Dentistry, Texas A&M University System Health Science Center, Dallas, TX, USA

Purpose: The objective of the present study was to investigate the mold filling of pure titanium and titanium alloys using a wedge-shaped mold with a marginal edge angle of 45°.
Materials and Methods: The metals tested were commercially pure Ti, Ti-6Al-7Nb, and Ti-6Al-4V; they were cast using an Ar-arc centrifugal casting machine. The castings were cut into four pieces parallel to the triangular surface. An optical microscope was used to evaluate mold filling as the distance between the tip of the cast wedge and the theoretical tip of the triangle. The data gathered for the 45° marginal edge angle in this study and for the 30° angle in a previous study were compared.
Results: The mold filling of the 45° angle was superior to that of the 30° angle for all three cast titanium metals.
Conclusion: Proper mold filling of titanium metals can be achieved with the 45° marginal edge angle compared with the 30° angle. (Int Chin J Dent 2004; 4: 67-71.)
Clinical Significance: Wide marginal edge angles are strongly recommended when titanium is used to fabricate dental appliances.

Key Words: casting, margin, mold filling, titanium.