I did something similar a couple weeks ago...I was finally landing back flips pretty consistently and I had never even came close to hitting my head while riding. The liner was starting to come out of my helmet and go in my eyes and it was bugging me so I quit wearing my helmet. All was fine for a couple days, but on the third day I had done some tuning and got more power out of my motor. I went bigger than normal and over rotated causing the nose to come up and I also fell forward and I hit my mouth on the handle pole base. I thought I had lost teeth for sure, but I still rode it out, lol. I went straight in to shore and loaded up my ski, trying not to cover everything in blood because my mouth was leaking profusely. Turned out I cut open the inside of my lips in 3 spots, I'm lucky that's all that happened and I went back to wearing a helmet all the time.