It aims to fix the defects of the consistency of the teeth or their occlusion to each other, and these defects take many pictures and shapes, including the exit of one of the teeth from the normal alignment of the teeth of the upper or lower jaw or the large or small size of a tooth so that it is not commensurate with the sizes of the adjacent teeth and the presence of spaces Between the teeth and each other due to some genetic diseases and defects of the upper and lower jaws, such as the difference in the size of each, where the size of the upper jaw is larger than the lower or vice versa, which leads to the problem of malocclusion, and this in turn causes one of the jaws to protrude abnormally affecting the patient’s appearance , And on the way to pronounce it and chew food

Types of calendar:

1- Fixed calendar

- Metal braces: it is the traditional orthodontic, as it consists of a group of metal brackets that are connected to each other by a metal wire, and fixed with an adhesive material, as they are fixed on the teeth with the possibility of adding rubber and other metal pieces according to the needs of each patient, and based on what he sees The doctor is appropriate, and his shape is not beautiful, which made him rejected by many people.

- Ceramic orthodontics: it is an orthodontic made of transparent ceramic pieces that resemble the color of teeth, which makes it beautiful and convenient compared to the metal orthodontic, but it is quick to break, and this requires great caution when consuming iced drinks and some types of foods.

- Back braces: It is an orthodontic that is installed on the inside of the teeth, which makes it acceptable and preferred by many people because its shape is unclear, but it may lead to some wounds in the tongue, and it is more expensive compared to the previous two types.

- Transparent Orthodontics: It is known as a transparent mold made of different plastic materials, as it is easy to install and take off, and it is also manufactured according to the size of the teeth and jaw.

2- The movable calendar is defined as a group of metal wires that have a light plastic base.