I really do advise you get a Vet to look at it. I had an injury like this and I was not prepared to have scarring. It took 48 stitches- all three levels of the gum had to be stitched, the outside, the muscle in the middle and the inside. It healed brilliantly, and you could not see the join. This was the olden days, when Vets worked for their money (sorry, sorry, but Vets must be the best paid people I know) and I was charged £1.00 per stitch + a small call out fee, even though it took him three hours to do it!
I would think the price has gone up a bit now......