Bayonets with sawteeth was popular from around 1870 to the first world war. The sawback on thebayonet was a useful tool, increasingly as the trench tactics got more popular.The teeth was usefull to remove barb and vegetation. I additon it could be used for tasks like picking wood and amputations. So the sawback bayonets was not designet to provide nasty wounds but as a saw.
In Norway we find use of sawteeth in sappørsabel (sapper sabre) M/1905. First this bayonet was used by the engineering corps. After 1912 it got used by the sanitary (medics) companies and nurses, now named knivsag (knife saw) M/1912.
The M/1905 sapper saber is a modified M/1860-bayonet, where the release button is removed, so the bayonet no longer can be secured to a rifle. The bayonet got shortened and the back of the blade got sawteeth.
In Germany and Switzerland there was a big production of sawback bayonets. In Germany specially in the start of WWI it got produced a large number of these bayonets. But it soon got unpopular because British propaganda managed to plant the impression that it was inhuman. It got told that British and French soldiers would torture and kill prisoners who got caught with sawback bayonets. From 1917 and onwards the Germans began to remove the sawteeth from existing bayonet, and new bayonets of this type was no longer produced.