Abstract: An orthodontic appliance comprising a main body for orthodontic treatment and a bonding base connected to the main body and capable of adhering to the teeth, wherein the main body and the bonding base each comprise calcium phosphate crystallizing glass. The calcium phosphate crystallizing glass preferably comprises CaO 10 to 60 wt %, P2O5 25 to 85 wt %, Al2O3 5 to 25 wt % and Li2O 0.01 to 5 wt %, and has Vickers hardness Hv based on JIS Z2244 of 4.5 GPa or lower, and bending strength based on JIS R1601 of 100 MPa or higher.

Abstract: An orthodontic appliance comprising a main body for orthodontic treatment and a bonding base connected to the main body and capable of adhering to the teeth, wherein the main body and the bonding base each comprise calcium phosphate crystallizing glass. The calcium phosphate crystallizing glass preferably comprises CaO 10 to 60 wt %, P2O5 25 to 85 wt %, Al2O3 5 to 25 wt % and Li2O 0.01 to 5 wt %, and has Vickers hardness Hv based on JIS Z2244 of 4.5 GPa or lower, and bending strength based on JIS R1601 of 100 MPa or higher.

Abstract: Glass ceramics used as dental material, artifical bone, etc. which contain 0.01 to 25 parts by weight of alkali metal oxides (R.sub.2 O), such as Li.sub.2 O, Na.sub.2 O, K.sub.2 O, Rb.sub.2 O, and Cs.sub.2 O, in 100 parts by weight of CaO-Al.sub.2 O.sub.3 -P.sub.2 O.sub.5 system material. During the casting for obtaining the glass ceramics, the molten fluid is sufficiently distributed to the fine corners of a mold, and the temperature for crystallization is low. Also, the time required for the crystallization is short and the crystalline formed shows no internal defects, and has high bending strength.