In order to determine the number of teeth on the saw blade you need, first consider the type of material you are cutting. Generally, a blade with more teeth will make a smoother cut in wood and other soft materials, while a blade with fewer teeth will make a rougher cut, but will be more suitable for harder materials such as metal. Additionally, consider the size of the miter saw and the type of cut you are making. The larger the miter saw, the more teeth you will likely need. Ultimately, the number of teeth on the saw blade you need will depend on the material and type of cut you are making.