A cartridge type dental injection device capable of easily and quickly mounting or removing a cartridge loaded barrel in or from a socket therein and capable of altering orientations of a viewing window in the barrel and of a cut surface of a needle as desired.
The cartridge type dental injection device comprises a barrel (9) adapted to be inserted in a socket (5) defined by a mounting member (5a) and having diametrically oppositee viewing windows (11) formed therein, the mounting member (5a) having a plurality of circumferentially spaced apart ball retaining holes (7), and a locking ball (8) placed in each of the holes, the barrel (9) being provided with an annular groove (12) adapted to receive a portion of each locking ball therein, and a locking ring (13) having an annular cam surface (14) and a relieving surface (15) positioned adjacent to each other and movable between a position where when the locking balls (8) are in alignment with the annular groove (12), the annular cam surface (14) pushes the locking balls (8) toward the annular groove (12) to bring portions of the locking balls into engagement with the annular groove and a position where the relieving surface (15) faces the locking balls (8) to release them from the annular groove (12).