Thanks for all of your advice. I actually ended up speaking with my FIL about the issue last night, and he was really good about it, he offered to speak to my MIL - and in his exact words "maybe then she will think before she does things..." Unfortunately she then locked herself away in her bedroom and we didn't see her until this morning where she was quite abrupt with us.... it was what we expected but hasn't made us feel any better about it. I am guessing that this isn't going to be as black and white as we thought...

To answer your question Lady Zaidie, DS has had teeth for about 7 weeks but his gums have been quite sore and swollen so I was waiting, and my MIL knew that - nevertheless it wasn't about the teeth being brushed anyway, it was just another indicator that my MIL (as my husband puts it) "acts like LJ is her son, not her grandson" and we decided that we needed to re-establish some boundaries so to speak.

Once again thanks for your input everyone - guess we'll just have to ride this one out