How bad is a hole in the side of my tooth?

Depends: It depends on the location and depth. Visit your dentist.

Depth Matters: It depends if the hole is active caries decay and if so, how deep it is. Molars do have a developmental pit on the cheek side of the tooth. It can be deep and discolored, but not decay and not important if you brush regularly with a Fluoride toothpaste. Moderate holes with decay can be restored with simple fillings. Deep decay can extend into the pulp and the tooth may need root canal treatment.

Not good for SURE: It's impossible to say without seeing it, but it certainly isn't a good thing, and won't get better without assistance from your dentist. Even if it doesn't hurt yet, please go today to get an evaluation and a discussion on treatment options. If you delay, treatment will get more complicated, take more visits, and cost more. It just still might still be a simple repair. Call today.

See the dentist: Sooner the better to avoid an abscess or loose the tooth.