Analysis of mesiodistal angulations of preadjusted brackets

Compliance with the ISO 27020:2019 norm of a sample of currently available preadjusted Orthodontic bracket systems. Are the actual dimensions as expected?

Background

Determine the exact slot dimension of a sample of a MBT prescription stainless steel conventional brackets from different manufacturers to compare the actual values with the nominal ones declared by the manufacturers and to verify the compliance with tolerance limits given by the ISO 27020:2019. Different batches from each manufacturer were evaluated to determine whether or not they are different in size. In addition, the geometry of the slot walls was assessed.

Methods

360 stainless steel preadjusted orthodontic brackets of 12 different manufacturers were assessed. All brackets had a nominal slot size of 0.022 by 0.028 inches, belonged to the right upper central incisor, and were fabricated with the metal injection molding technique (MIM). For each manufacturer, three different manufacturing batches were evaluated. Brackets were coded using a single-blind design.

Results

All bracket systems in the study group except one displayed a statistically significant difference with the nominal declared value, although only four of the systems did not comply with the tolerance limits established by the ISO 27020:2019. In most of the systems, the slot height was oversized when compared to the nominal one. A significant interbatch variability was found in most of the evaluated systems. Most of the brackets walls were divergent.

Conclusions

The dimensional accuracy of commercially available metal brackets is not guaranteed. The respect for the norm should be enforced as well as the quality controls along the manufacturing process since orthodontic brackets are a precision medical device.

A Comparative Study of the In-Built Torque and Slot Size of MBT Prescription Bracket of Different Manufacturing Companies: A Stereo-Microscopic Study

Torque is produced by a twist in an “archwire” that creates a couple when interacted with a “bracket slot.” Depending on the magnitude of the twist, the size of the wire, the built-in torque and the size of the slot, the archwire expresses torsional forces to the teeth. When brackets are manufactured, some variations may inadvertently occur in the dimensions of the bracket slot. Hence this study was done to determine the accuracy of different manufacturer’s dimensions of bracket slots and the built-in torque.

Method:

Seven upper right central incisor brackets of Mclaughlin Bennet and Trevisi (MBT) prescription with 0.022-inch slot from 5 different manufacturers were taken to assess the accuracy of bracket slot dimensions and built-in torque. A stereomicroscope was used to accurately determine slot dimensions and built-in torque.

Results:

The results showed that all the bracket slots measured in this study were oversized when compared to the standard value. Dentaurum showed significant difference from the ideal slot size and brackets from JJ Orthodontics and Desires showed highly significance difference from ideal slot size. The mean values for built in torque were less in all the brackets. The brackets from JJ Orthodontics and Desires showed highly significant difference from the ideal built in torque values.

Interpretation and Conclusion:

The above findings of the study suggest that one should be cautious when choosing a commercially available brand in day to day practice as some of the materials may not fulfill the desired standards.

Assessment of dimensional accuracy of preadjusted metal injection molding orthodontic brackets

Background:

the aim of this study is to evaluate the dimensional accuracy of McLaughlin, Bennett, and Trevisi (MBT) brackets manufactured by two different companies (American Orthodontics and Ortho Organizers) and determine variations in incorporation of values in relation to tip and torque in these products.

Materials and Methods:

In the present analytical/descriptive study, 64 maxillary right central brackets manufactured by two companies (American Orthodontics and Ortho Organizers) were selected randomly and evaluated for the accuracy of the values in relation to torque and angulation presented by the manufacturers. They were placed in a video measuring machine using special revolvers under them and were positioned in a manner so that the light beams would be directed on the floor of the slot without the slot walls being seen. Then, the software program of the same machine was used to determine the values of each bracket type. The means of measurements were determined for each sample and were analyzed with independent t-test and one-sample t-test.

Results:

Based on the confidence interval, it can be concluded that at 95% probability, the means of tip angles of maxillary right central brackets of these two brands were 4.1–4.3° and the torque angles were 16.39–16.72°. The tips in these samples were at a range of 3.33–4.98°, and the torque was at a range of 15.22–18.48°.

Conclusion:

In the present study, there were no significant differences in the angulation incorporated into the brackets from the two companies; however, they were significantly different from the tiP values for the MBT prescription. In relation to torque, there was a significant difference between the American Orthodontic brackets exhibited significant differences with the reported 17°, too.