An oral functional appliance is a device used in dentistry to adjust occlusion by harnessing the natural forces of jaw muscles activation or bone growth. Oral functional appliances are typically used when the relationship between the jaw and midface or the width of the palate are the source of malocclusion. This is different from typical oral appliances, such as retainers or clear aligners. They focus on dentoalveolar relationships, or the relationships between the position of the teeth in the jawbone.