How quickly would you lose your teeth if you never brushed?

Hard to say: I can't tellyou how long it will take to loose your teeth without brushing. Part of this answer depends on genetics, diet, smoking, drugs, and other medical conditions you may have. Don't stop brushing. It will affect your teeth and your general health.

Please don't: Try to find out. Generally, years. Some patients defy reason & science and have minimal problems. However, the vast majority can get major cavities in 6 months which lead to root canal therapy or extractions. One tooth at a time, until they have none left. Then it's dentures or implants & thousands to tens of thousands of dollars to get something inferior to natural teeth. Please brush and floss!