A new trial concludes that early class II elastics reduce fixed appliance treatment duration?
It is standard clinical practice for us to delay the use of Class II elastics until our patients are in rectangular wires. This is due to concerns about the lack of control when we are in light wires. There has been limited research on this practice, with our evidence mostly comprising clinical experience and case reports. I was therefore interested to see this new paper that examined the effects of early and late Class II elastics.
A team from Egypt did this study. The Angle orthodontist published the paper.
Maha Sabry Sayed; Mais Medhat Sadek; Noha Hussein Abbas
Angle Orthodontist: Advance access DOI: 10.2319/113024-985.1
What did they ask?
They wanted to answer these question
“What are the effects of early vs late Class II elastic wear with respect to dental changes, and duration of treatment to level, align and correct AP discrepancies”?
What did they do?
They conducted a two-armed parallel group randomised controlled trial with a 1:1 allocation.
The PICO was
Participants
Orthodontic patients with half unit Class II buccal segment relationships and an overjet exceeding 4mm in the permanent dentition, treated with fixed appliances using a non-extraction approach. One operator treated all the patients.
Intervention 1 . Early group
They asked the early group to wear Class II elastics with a force of 2-3.5 ounces when appliances were placed and they were in alignment wires. When the operator inserted 016×022 stainless steel wires, the elastics were altered to provide 4-5 oz force.
Intervention 2. Late group.
In this group, the participants began wearing elastics when the operator fitted 016×022 ss wires.
Outcomes
The primary outcomes involved multiple cephalometric measurements. Secondary outcomes included the duration of treatment required to achieve levelling and alignment, as well as the correction of the buccal segment relationship. They also assessed the smile line from facial photographs.
The endpoint for the correction of the buccal segments was determined by the operator. This was verified by another blinded examiner to ensure the reliability of the assessment.
They collected data at the start of treatment and when the buccal segments were corrected. Most of the data were collected from cephalograms.
They performed a sample size calculation based on previous studies, which indicated that they needed 20 participants per group. The team used a pre-prepared randomisation process, but they did not clearly describe the method of allocation concealment It was not possible to blind the operator and patient to the treatment allocation. However, they did analyse the data blind.
What did they find?
They reported a total of 29 cephalometric measurements and conducted statistical tests across the groups for these measurements. There were no statistically significant differences between the groups in the dental measurements. When examining the skeletal values, several statistically significant differences were found, but I thought these were not clinically relevant.
However, they found that the duration of treatment required to correct the buccal discrepancies and level the arches varied between the groups. It averaged 6.47 (SD=2.5) months for the early group and 14.24 (SD=3.8) months for the later group. This resulted in a statistically significant difference of 7.7 (95% CI=4.7-10.8) months. I think that we can all agree that this is clinically significant.
Their conclusion was
“Treatment duration for alignment and levelling was less in the early elastic group. There were minimal other differences between the protocols”.
What did I think?
This was an interesting small trial that examined a common question relevant to our clinical practice. When considering the effects of different protocols on dento-skeletal morphology, it is both interesting and reassuring to find no differences between the elastic protocols. I usually prefer to start elastics early, and these findings suggest that doing so does not cause any problems.
The most notable finding was the considerable difference in treatment duration. When we critically read a study that shows a large discrepancy, we need to examine all aspects of the study thoroughly.
In this regard, we must recognise that the endpoint chosen by the authors was not the conclusion of treatment. We cannot assume that early application of elastics results in a shortening of total treatment time. As a result, it would be good if the authors followed up these patients until they had completed treatment.
There is no doubt that their findings are interesting, and we clearly need further trials in this area to evaluate what is a potentially important finding. This study is a good first step.
You need to decide whether these issues influence your interpretation of the results of this paper.
Emeritus Professor of Orthodontics, University of Manchester, UK.
Dear Dr. O’brien,
Thanks for sharing the article and your opinion. I will leave my comment below.
The use of Class II elastics during the initial stages of treatment, particularly with early-stage wires, tends to produce more pronounced side effects. These side effects often require considerably more time to correct later and may even lead to biological compromise. Given this, one might question why the study did not demonstrate these findings, and why Class II correction appeared faster in the group that used elastics early.
The superimposition presented in the article clearly shows significant mesial inclination of the lower teeth and distal inclination of the upper teeth. Moreover, attaching elastics to the premolars and canines while using round NiTi wires promotes unwanted rotation, further contributing to a false appearance of Class II correction. However, these issues were not analyzed in the study, as no dental models were evaluated and the final occlusal outcomes were not assessed.
In such cases, relapse is a likely outcome, since excessively inclined teeth tend to upright according to their apical positions—leading to the reappearance of the Class II relationship. Consequently, any perceived time savings may be misleading, as clinicians will ultimately need to address multiple side effects later, a process that can be considerably more time-consuming.
Bests!
Marcel Farret
Thank you, Dr. O’Brien, for sharing your opinion on our work. It is an honor to be featured on your reputable blog. We hope that our humble contribution adds value to the clinical field. Thank you once again.