Yes they are a problem...I used an entire bottle of CA glue while shaping it....Mammoth Tooth is about as stable as a Waterbed and it could come apart tomorrow or last ten years...Time will tell.Nice looking handle!
Are the fissures a problem that need to be sealed or filled? Is it stable like that?
If you epoxy a mammoth tooth scale to some micarta it will work Great...Having a 28mm hole 18mm deep at the top probably will cause me problems...I have used it in my knife handles alot,but I don't know if anyone has made a brush handle with it.I only know the material from knife handles which are obviously only thin slabs. I have never seen such a big piece used.