the other hand, fixed appliances cannot be taken off as they remain bonded to the teeth during treatment. Fixed appliances Fixed orthodontic appliances are predominantly derived from the edgewise appliance approach, which typically begins with round wires before transitioning to rectangular archwires for improving tooth alignment. These rectangluar wires promote precision in the positioning of teeth following initial treatment.In contrast to the Begg appliance, which was based solely around round wires and auxiliary springs, the Tip-Edge system emerged in the early 21st century. This innovative technology allowed for the utilization of rectangular archwires to precisely control tooth movement during finishing stages after initial treatment with round wires. Thus, almost all modern fixed appliances can be considered variations on this edgewise appliance system. Early 20th century orthodontist Edward Angle made a major contribution to the world of dentistry. He created four distinct appliance systems that have been used as the basis for many orthodontic treatments today, barring a few exceptions. They are E-arch, Pin and tube, Ribbon arch and Edgewise systems. E-arch Edward H. Angle made a significant contribution to the dental field when he released the 7th edition of his book back 1907, which outlined his theories and detailed his technique. This approach was founded upon the iconic "E- Arch" or 'the-arch' shape as well as inter-maxillary elastics. This device was different from any other appliance of its period as it featured a rigid framework to which teeth could be tied effectively in order to recreate an arch form that followed pre-defined dimensions. Molars were fitted with braces and a powerful labial archwire was positioned around the arch. The wire ended in a thread and to move it forward an adjustable nut was used, which allowed for an increase in circumference. By ligation, each individual tooth was attached to this expansive archwire. Pin and Tube applilance Due to its limited range of motion, Angle was unable to achieve precise tooth positioning with an E-arch. In order to bypass this issue, he started using bands on other teeth combined with a vertical tube for each individual tooth. These tubes held a soldered pin which could be repositioned at each appointment in order to move them in place. Dubbed the "bone growing appliance", this contraption was theorized to encourage healthier bone growth, due to its potential for transferring force directly to the roots. However, implementing it proved troublesome in reality. Ribbon Arch