Abstract: An improved tooth 21 and tooth holder 22 assembly for use with a digging implement such as a post hole digger has a first retention member 23 and a second retention member 24 each of which can be used in isolation or in combination. The first retention member 23 comprises a nylon plug having opposed serrated teeth 25 and which is pushed into an opening in the tooth holder 22. The tooth contains rigid profiles 26 and when the tooth is pushed into the tooth holder, the serrations and profiles mesh together to positively retain the tooth within the tooth holder. The second retention means 24 comprises a resilient pin. The tooth and the tooth holder have a positive and negative wedge type shape which allows the tooth to be attached in one orientation only.