No, nothing in life is permanent. When you are 40 you will not look the same as you do now at 20 and when you are 60 you will have changed again. ALL tissues change with the aging process. As the muscles of our face change in tonicity, our dental apparatus changes through use over time, our periodontal supporting status weakens over time and there are minimal amounts of skeletal and soft tissue growth that occur, all of this causes the positions of teeth to change over time. The majority of the orthodontic correction achieved should be relatively stable, depending upon the particular aspects of your orthodontic problem, and the method by which it was treated, to expect your teeth to remain permanently straight is unrealistic. However, there are methods by which we can minimize any changes over the course of time. I am referring to lifetime retention. There are various types of retainers that can be permanently affixed to the teeth to prevent them from moving. You should speak to your orthodontist about this.