I Got Hit in the Mouth & Cracked my Front Tooth. Dentist Said It's Fine & Told Me I Didn't Need Treatment. How Common is That?

The crack is on my front right tooth, and it's very thin: it's hard to see except for in certain light. It goes from my gum to the center of my tooth, and does not go all the way through the tooth. I only have sensitivity in my tooth, not really pain, although my tooth does feel a lot of pressure when I bite down, but my dentist said that that's due to a bruised ligament in my tooth from getting hit.