Does filing down a fake tooth make it more prone to chipping? (Photo)

I saw a dentist and he offered to file down a chip in my right front tooth that had been present for 7 years. The lower half of that tooth is fake because I fractured it in a bike fall when I was 7, and had a root canal done then. I am now 21. Less than a year after I accepted this free casual offer to file down that chip in my tooth it developed a chip in the same place. Did filing down the fake bit of tooth compromise the integrity of that tooth, and if so should the dentist have known better?