Abstract: A replaceable tooth assembly. A number of tooth assemblies are provided round the periphery of a microtrenching blade. The assemblies include a cartridge, usually welded to the periphery of the microtrenching blade, and a tooth, which has a projection or flange shaped to fit within a cavity formed in the cartridge. The cartridge and projection each have a transverse hole formed in them, which, when aligned, form a continuous passage for placement of a removable pin which is used to join the cartridge to the tooth body. The cartridge may also have a more radially-aligned channel which intersects the cavity, which a rubber shim may be placed in. Such a shim reduces the relative vibration between the tooth and cartridge, improving life and reducing wear.