Great sentence! Here are two easy, correct ways to say it:
- Very simple (best for a 4-year-old): Hyenas have very strong teeth. They can crunch bones like crackers.
- One sentence (more grown-up): Hyenas' teeth are so tough that they crunch bones like crackers.
Why? The two short sentences are easiest to understand. The one-sentence version is also correct if you add "that" to make it flow smoothly. The original is understandable but adding "that" or splitting into two sentences sounds clearer.