The first problem facing orthodontics is how to choose the right aligner for you, often referred to as “braces”. Depending on the condition of the teeth and different needs, the choice of aligners will be different. Today I’ll introduce you to the common orthodontic appliances. First, the lip side of the fixed orthodontic appliance The lip side of the fixed orthodontic appliance is the earliest orthodontic appliance, is also the most widely used, it is adapted to a variety of complex cases of misalignment of teeth. It is divided into two main types metal bracket aligners and ceramic/monocrystalline bracket aligners. Metal brackets are the most commonly used orthodontic treatment and consist of an archwire and a number of metal brackets. The traditional metal brackets are ligated brackets, which are held in place by ligating wires or ligating rings between the brackets and the archwires. Currently, self-ligating brackets are increasingly used in clinical practice, where the archwires are held in the brackets by a locking device. The advantage of metal brackets is that they are technically mature, widely available, and relatively low cost. The disadvantage is that they are more foreign body sensitive, more difficult to clean and less aesthetically pleasing. Ceramic/monocrystalline brackets take the original metal brackets and replace them with a translucent ceramic/monocrystalline material that is close to the color of the teeth. The advantage is that they are more aesthetically pleasing than metal brackets. The disadvantage is that the price is slightly more expensive compared to metal brackets. Second, lingual fixed aligners is a method of aligning teeth on the lingual side, the principle is similar to the lip side. The biggest difference is that it avoids the exposure of “steel teeth” and meets the aesthetic requirements of the patient. The advantage is that they are very invisible. The disadvantage is that the lingual side has a strong foreign body sensation, is more difficult to clean, expensive and complicated to operate. The current clinical use is less. Third, invisible braces without brackets invisible braces use a special material, showing a transparent color, invisible effect is good. It uses a completely personalized design and a three-dimensional diagnostic software that allows the entire treatment plan to be designed through computer simulation of tooth movement prior to orthodontic treatment. Advantages:Self-removal, comfortable and aesthetically pleasing, largely invisible from the outside, relatively less frequent follow-up visits, easy to maintain oral hygiene. Disadvantages:Relatively expensive, requires certain financial conditions of the patient, and requires a high degree of patient cooperation.