Nowadays, many scholars in orthodontic circles advocate the concept of light force correction. In order to achieve the effectiveness of light force correction, the first thing is to reduce the friction of the correction system. Since the late 1990s, some new fixed appliances have been introduced in the world. One of the directions of improvement or renewal is to reduce the friction of bracket groove, so as to realize light force correction.

        In 1997, kusy et al. Proposed that the sliding friction (RS) can include three parts: classical friction (FR), elastic binding (BI) and physical notching. According to the relationship between the angle between the bracket and the arch wire inclination and the critical angle (8 c), It can also be divided into two states: sliding in passive state (8 < 8C, passive frictional configuration) and sliding or moving in active state (8 8C, active frictional configuration); The composition and size of sliding friction force are different in different states (Fig. 13-20). It has been confirmed that when the arch wire

        Phenomenon. Therefore, he selectively took tooth extraction correction for some patients with malocclusion, and achieved good results. At the same time, it is not easy to move the teeth with Jianqian square wire appliance, and the traction required is relatively large. Dr. tweed has made a significant improvement on the square wire appliance. He continued to adhere to the principle of overall tooth movement, put forward the concept of preparation anchorage and the necessity of strengthening anchorage, improved the three sequence bending operations, and emphasized the extreme importance of using external force, so as to make the square wire arch technology reach the mature stage of not only the correction of thousands of tooth extraction cases, but also the correction of thousands of tooth extraction cases, and form an effective tweed square wire arch technology, It is recognized as the standard square wire bow technology. Later, the single bracket was continuously improved and appeared one after another

        Siamese double rib wide brackets and preformed sequential brackets (i.e. straight wire arch brackets) improve the level and accuracy of tooth control. However, it has also paid a price, which makes the often needed tooth and jaw displacement more difficult. It is still not easy to open the bite, and it depends more on the application of external force. However, many doctors are reluctant to use external force devices, and there are problems in the cooperation of patients. Doctors prefer to use intraoral traction to move teeth, such as intraoral traction or intermaxillary traction. Compared with the high traction force outside the mouth,

        The force line of internal traction is far away from the resistance center of the tooth; In the case of subtraction, it is bound to cause the canine crown to rotate and move backward along or around the resistance center. The passive range of the traditional bracket groove is small. With the backward movement of the canine, the arch wire will be forced to bend down

        In the subtractive cases, the distal movement mode of the canine, the intraoral traction line is far away from the resistance center, and the canine crown rotates around the resistance center, resulting in the downward bending of the arch wire and the obvious increase of the friction force

        The friction between the wire and the groove increases significantly (Fig. 13-22), which means that it has entered the active state with high friction (8 anus). At present, although it has entered the era of straight wire arch, edgewise appliance has been rarely used in orthodontic clinic. But more math

        The author believes that tweet square wire bow technology reflects the essence and concept of square wire bow technology and is the basis of modern straight wire bow technology; If the training of standard square wire bow technology is carried out before learning the straight wire bow technology, it will be very beneficial to better understand and master the straight wire bow technology.

        2. Review of Begg filament appliance and technology Dr. Begg, an Australian orthodontic pioneer, received training in band arch technology and edgewise square wire arch technology at angle from 1924 to 1926. When Dr. Begg returned to Australia

        After several years of non extraction treatment with edgewise appliance, it was found that the largest cases had recurrence, blindly expanded the dental arch and improved the profile of soft tissue. Therefore, in 1928, Dr. Begg used tooth extraction correction for some selective cases. Soon he felt that the edgewise appliance was not ideal in closing the extraction space and correcting deep overbite, and often needed extraoral anchorage, but many patients did not like to wear extraoral anchorage headgear, and some doctors were unwilling to use it. Dr. Begg believes that the problem lies in the edgewise bracket. In the early 1930s, he resumed the use of band bow brackets. Only the opening of the bracket groove was changed from reserved to limited, which was later called Begg bracket (Fig. 13-23); Give up the square wire bow and change it into a thin round wire bow. The passive range of this bracket groove is significantly increased. Therefore, under the action of continuous light force, it is easier to make the crown tilt near and far (Fig. 13-24), close the extraction space and open the front tooth occlusion without external force as anchorage, which opens up a new way for the correction of dental deformity. However, with the deepening of clinical practice, some scholars feel that Begg appliance sometimes has certain or even considerable difficulty in the completion stage of correcting dental deformity. The arch wire enters the groove vertically from the limiting side and its related studs, which seems not very beneficial to the study and popularization of differential power technology.

        Begg bracket and edgewise bracket have been less used so far. But this is one of the simple and effective design examples. Obviously, their advantages and disadvantages are complementary. Therefore, how to design brackets that can summarize their strengths and abandon their shortcomings has always been the pursuit goal of scholars.

        （2） The advent of tip edge straight wire appliance and technology

        Based on 30 years of experience in applying Begg filament arch correction technology, Dr. kesling in the United States realized that in addition to the extraction space

        When the groove is in the passive state of 8 < 8C, the sliding friction to be overcome is mainly the ligation friction force of ligation wire or ligation skin ring; However, in the active state of 88c, the friction force of tooth movement increases significantly. Even if the ligation friction force is eliminated, the tooth movement in the active state still needs to overcome the large friction binding (BL) and even the large physical resistance (no).

        Therefore, not only eliminating the ligation friction is an obvious measure to reduce tooth movement, but also trying to expand the passive state or range of the bracket groove, so as to avoid entering the active state with large friction as far as possible when moving teeth, which is a more important aspect of bracket improvement. The self-locking bracket eliminates the ligation friction, and the tip edge bracket significantly expands the passive state or range of the groove; The transmission bracket with thousand cusps is compatible with the advantages of self-locking bracket and tip edge bracket, which not only eliminates the ligation friction, but also significantly expands the passive state or range of the groove. The following introduces the tip edge straight wire appliance and technology, the transmission straight wire appliance and technology and the self-locking bracket technology.