A well-proportioned occlusion occurs when all of your upper and lower teeth are correctly aligned and you can bite together evenly. Your upper front teeth should overlap slightly with your lower front teeth when you bite together. If your jaw is not properly aligned, you may have difficulty chewing or pronouncing specific sounds clearly. Jaw surgery corrects a malocclusion (abnormal bite) that results from underlying skeletal disharmony that can't be corrected with orthodontic treatment alone. Additional procedures might be necessary, including movement of the chin bone and nose, cheek implants, liposuction (fat removal), and bone grafting. The operation can take two to 10 hours depending on the difficulty of the procedure.