## 1 Introduction  
The ideal objectives of orthodontic treatment are to achieve good functional occlusion, proper aesthetic, and finally to ensure the stability of the result. Correct axial inclination and angulation of the dentition are essential to achieve these treatment goals [1, 2, 3].  
Until the introduction of the first straight wire bracket system by [PERSON] in the 1970s, orthodontic brackets had no information built into the slot or at the base. Orthodontists would therefore add the required force system by forming bends in the archive [1, 4].  
Today, the vast majority of brackets on the market are pre-adjusted, with torque and angulation built into the bracket slot or base [1,3,4].  
The full expression of the information is achieved by inserting an archive with a cross-sectional size that fully engages the bracket slot. From a theoretical point of view, in a pre-adjusted system, the teeth should be guided to their ideal position without the need for additional wire bending due to the information incorporated in the bracket slot [5,6]. Despite the information incorporated in the bracket slot, in a clinical setting, it is still necessary to bend the archives to achieve correct alignment and intercuspation at the end of treatment. Third order (torque) compensation on working or finishing wires is needed in most cases, resting efficiency and simplicity to the straight wire appliance protocol [6,7]. The lower performance in the full expression of the inbuilt information can be due to a variation in tooth morphology, errors in bracket placement, or the inaccuracy of the bracket manufacturing process. The precision of the manufacturing process is a grounding assumption of the straight wire technique, as a variation of the inbuilt information from that declared will obviously imply lower appliance performance [7,8].  
Thanks to [PERSON] work, we know how the correct expression of the bracket meso-distal inclination (tip) is needed to express the desired tooth/root angulation in the bucocapalatal direction (torque) incorporated into the bracket slot [9]. Tip and torque information are therefore closely related and mutually dependent regarding their correct clinical expression. Establishing the correct torque in the anterior segment of the dentition is a key factor in obtaining proper intercuspation in the posterior segments and achieving a class I molar relation [7,8].  
Due to the importance of bracket accuracy, quality standards have been established. The European Committee for Normalization released the ISO 27020:2019 as a reference norm in the European Union for orthodontic brackets and tubes. The norm specifies the standardized protocol to test the dimensional accuracy and reports the tolerance limits between those declared by the manufacturers and the real limits [10]. The objective of our study was to evaluate the inclination (tip) and angulation (torque) values of a pool of McLaughlin, Bennett and Trevisi (MBT) prescription stainless steel brackets from different providers and to compare the actual values with the nominal values. In addition, the compliance with the tolerance limits established by the ISO 27020:2019 norm was assessed in the different batches from the same provider.