Answer:
I had a cancerous growth removed from my lip in 1983 and you can't tell where it was. I had 7 external stitches and 12 internal ones. It depends on whether the stitch line was horizontal or vertical. Mine was vertical and so looks just like a normal crease, the only time it is visible is when I get cold and it gains a slight blue tinge. If they made that good a job of mine all those years ago they would probably have made a better job of your brothers with the progresses made in modern plastic surgery.
yes. sorry to say. You can try to prevent the scarring but in most cases it will. He needs to massage the area two to three times per day at least with either a massage oil or just a moisturiser. There is a product on the market called Bio Oil which is meant to reduce scarring and prevent stretch marks which he could buy but it is around £10 a bottle which in my opinion is quite pricey, but hey your face is your face.
Good luck with it and I hope the scar isn't too visibile
It depends on who did the stitching! If a consultant plastic surgeon did it then - no. If was your local GP or a junior doctor in casualty then it probably will leave a small scar. Girls are far more likely to be refered to a consultant than boys which seems rather sexist to me.
All deep cuts scar but they can be reduced. Bio oil is pretty good but, as has already been pointed out it's pretty pricey. The next best thing is cocoa butter. He will have to wait for the cut to heal, none of these things should be put on an open wound. Then when it's healed if he gently massages cocoa butter or bio oil on and around the scar two to three times a day it will accelarate the healing process and limit the long-term scarring. I have tried this on myself and I have a year old scar which looks like it's easily over 5 years old. Bio oil actually helps to reduce older scars too, incase you're interested ;)
My little brother was bit in the face by a cocker spaniel when he was like...5 and now he's 14, and the scar is still there, but it's really light...it will fade over time especially if he's young. =)
After it heals completely, he can use Cocoa Butter. The butter will lighten it up a Great Amount. The doctors have so many uses, that I doubt if it will scar but very little.