Hello; It doesn't work. Also known as reverse jaw. When the mouth is closed, the mandibular anterior teeth are located outside the maxillary anterior teeth. This requires orthodontic treatment. 1. In general, it is still about 12 years old, which is the best age for orthodontics. However, sometimes you can intervene early in the case of malocclusion. I suggest you take your daughter to the orthodontics department for examination and consultation to see if it is suitable for tongue plate now. 2, there will be discomfort in correcting teeth, it may be a little painful at first, but it is generally tolerable. If the dentition is crowded and it is necessary to extract teeth, it is responsible not to extract teeth. 3, wearing braces will cause discomfort, generally no obvious pain. General orthodontic needs 1.5 years, two years.