Objectives: There are several commercial phosphate-bonded investments for quick heating (QHM), however their characteristics have not been clearly confirmed. The purpose of this study was to evaluate characteristics of the commercial phosphate-bonded investments for QHM. Methods: Two commercial phosphate-bonded investments for QHM (Z4 C&B, Neirynck & Vogt, Belgium; Maruvest-Speed, Megadental, Germany) were examined. Dimensional changes of the investments during setting and heating were measured three times by a dial gauge and a dilatometer, respectively. Surface roughness (Ra) of the investments was measured using a surface analyzer. Five hexagonal-pillared castings (20mm x (5.4+7.4mm) x 2.1 mm) of Ni-Cr alloy (a-alloy, Yata Dental, Japan) were obtained using an induction melting centrifugal casting machine (3KWCCM, Li-hsin, Taiwan). The longitudinal accuracy (Length) and the transversal deformation (Bend) of casting were also calculated based on the dimensional change of the wax pattern and the casting. Data from two investments were analyzed by the t-test (p<0.05). Results: Obtained characteristics are summarized in table below (Means and S.D.):

Code	Setting expansion (%) 30 min	Thermal expansion (%)	Surface roughness(Ra, µm)		Dimensional accuracy
			Green	Fired	Length (%)	Bend(µm)
Z4 Maruvest	1.08(0.11) 2.17(0.16)	1.23(0.08) 1.39(0.14)	2.68 (0.06) 4.91 (0.20)	2.14 (0.03) 4.09 (0.13)	0.87 (0.09) 1.69 (0.10)	-34 (0.02) -27 (0.01)

The setting expansion, the length and the surface roughness of Maruvest were significantly greater than those of Z4. The mold did not crack during quick heating and casting. The Obtained castings have not fins on the surface. Castings from two investments showed increase in length and deformation for outward probably due to large expansion. Conclusions: These results suggest that examined two commercial phosphate-bonded investments possess sufficient characteristics for quick-heating method except relatively greater expansion.