Asking a serious question here. Why does it need to be corrected? Bear did this when he was younger a lot but never hard and he learned quick enough what OUCH meant. He grew out of it. Do some dogs not grow out of it? I always felt like that was just part of his puppy charm.
From my experience with my own and training other dogs for people some dogs do not outgrow it in fact it gets worse if you don’t correct it. Some dogs learn more easily than others too.
If you were consistently saying “ouch” when Bear did this when he was younger in a way you were training him without realizing it and he responded well.
When Shelby was younger she was very mouthy to the point her sharp puppy teeth would scratch and slice my fingers. Not a bite just enough to hurt. We used “OUCH!”
As a command along with some other gentle techniques (press tongue down with thumb for a few seconds) to get her to realIze it’s not ok to mouth us and replaced it with a toy or chew bone instead.
She’s 3 now and even at the peak of her play excitement the most she will ever do is gentle mouthing for a split second before she realizes that’s no good. Even if anyone tried to shove a hand or finger in her mouth now, she will pull away and not grab on at all. This is reenforced often during playtime
Just to be sure she doesn’t forget.