How long does it take to fix overjet and overbite?

Depends on severity: Depends on severity and age and methods. Children can undergo progressive 2 phase treatment for several years and acheive a normal face. Adults may need orthognathic jaw surgery along with orthodontic treatment for 1-3 years. Less severe cases can be treated by cutting the bone surrounding the teeth, grafting it back and orthodotics..Maybe a year.

And what else?: Why do you have an ob/oj problem? Is the problem dental, skeletal, or both? How severe is the problem? What else is involved in your malocclusion? Is treatment for an adult or a growing child? And so many other questions. Average time in braces is 18 months. Some cases require 2 phases of rx, or prolonged rx, or braces and surgical rx. Talk this over with a qualified orthodontic specialist.