We have one of our old men, Joey of OCRA (27 months old) needing a little TLC in the tooth department. For about a month I have been trimming a sharp point he keeps missing in his natural bruxing and gnawing. The tooth appears to be growing even faster now that we have had to trim it weekly. Such a sharp point. Since this jutting point was in the back of his tooth, if I was not looking CLOSELY in his mouth, it could have been too late, causing some terrible pain/damage. I am very thankful he will let me mess in his mouth. Often the vet will need to sedate the rat to trim it. (The tooth can also shatter if you are not careful so please do not take on tooth trimming without learning from an experienced person.)
I have included some great links for further reading on the tooth.