No. Age is no bar for braces. Many adults are choosing tooth-coloured ceramic braces, which hardly show. Orthodontics is usually the most cost-effective treatment because it means eliminating the cosmetic problem while retaining your natural teeth. Restorative treatment always has a limited "life expectancy" on any restorations, meaning you will have to continually pursue whatever treatment you choose.
Usually protruding lower jaw can be best treated at an very early age, later on it requires orthodontics and orthognathic surgery to correct the same.