November 25, 2024

Indirect bonding may or may not improve the efficiency of orthodontic treatment

Today’s post focuses on indirect bonding once again. One of the most significant benefits of this technique is the increased efficiency in bracket placement, which can potentially lead to better treatment outcomes. This new trial examines these important factors. I will also use this paper to demonstrate how I critically appraise a trial.

In a post a few weeks ago, I discussed a new trial that looked at Direct v Indirect bonding and concluded that there were limited advantages to indirect bonding. This new study also sheds some light on these interesting clinical issues.

A team from Okayama, Japan did this study. The EJO published the paper.

It was great to see that this paper was open-access.  

When I evaluate a paper, my first consideration is its relevance to my clinical practice. This particular paper aligns with my criteria. If I think that a paper’s subject matter is not relevant to my practice, I usually choose not to read it.

What did they ask?

They did this study to 

“Evaluate and compare the direct and indirect bonding methods through comprehensive and detailed clinical evaluation”.

What did they do?

They did a single-centre, open-label, quasi-randomised controlled clinical trial.

The PICO was

Participants

I could not find any information on the patients in the study in the methods. But this was contained in a supplementary table. This revealed that the participants were over 12 years old and had a malocclusion.

Intervention

Indirect bonding

Control

Direct bonding

Outcomes

The primary outcome was total treatment time.  Secondary outcomes were level of discomfort during bonding, oral hygiene, and post-treatment occlusal index scores using the OGS index.

Further details of the method

Twenty-one orthodontists treated the patients in a university setting. Their clinical experience ranged from 1 to 6 years.  They used pre-adjusted plastic or metal brackets. When the crown length was short, the metal brackets were used only on the upper and lower premolars. Most cases had plastic brackets placed.

The team randomly assigned the patients to the direct or indirect bracket group. One person used medical record numbers to allocate the interventions.

The team detailed their sample size calculation based on the primary outcome of total treatment time. They correctly used data from a previous retrospective study and wanted to power their study to detect a meaningful difference of 3.16 months between interventions. They calculated that they needed 50 participants per group if they wanted to take dropouts into account.

This was clear and when I repeated the sample size calculation I got the same result.

They used simple multivariate statistical tests to evaluate the data.

What did they find?

They identified a possible sample of 1059 participants and excluded 906 of them. This was because they did not meet the inclusion criteria.  

They enrolled 72 patients into the indirect group and 81 into the direct.  However, 14 in the indirect group (19%) and 15 in the direct group (18%) dropped out.  This left a final sample of 58 in the indirect group and 66 in the direct bonding group.

Outcomes

Let’s have a look at the outcome measures

When they looked at the overall treatment time. This was 30.51 (SD=7.27)  months for the indirect group and 34.27 (8.87 months) for the direct group.  They stated this was significantly different.

When they looked at chair time. They defined this as the time it took for bonding and banding. They found that the time required to bond brackets from the mandibular incisors to the molars was 35.91 (SD=15.51) minutes for the indirect group and 58.51 (SD=25.4) minutes.

The only other data that I want to consider is the number of bracket failures. This was 7.28 for the indirect and 2.92 for the direct group. The number of repositions was 3.2 for the indirect and 8.89 for the direct group.

When they looked at the outcome of their treatment with the Objective grading system of AAO they found a mean of 47.31 (8.17) for the indirect and 53.74 (7.74) direct.  Again, this difference was statistically significant.

Their final conclusion was rather unclear and the text did not reflect the abstract.  I, therefore, took this from the abstract

“Indirect bonding may improve the efficiency of orthodontic treatment”.

What did I think?

I have put a lot of thought into the text (highlighted in red). While I have expressed several criticisms, we need to consider whether the issues I pointed out influence the results and conclusions. My next step is to analyze the impact of my most significant concerns.

Firstly, we lack information about the nature of the malocclusions and the treatment provided. For example, the distribution of non-extraction/extraction treatments. This makes it difficult to assess their relevance to my practice. My uncertainty regarding the findings is further compounded by the absence of details about the operators. Notably, 21 operators treated 112 patients, but we do not know how many patients each operator treated. Additionally, the operators varied in experience, ranging from one six years of experience. Consequently, we must assume that the results are primarily applicable to inexperienced operators. This may also explain the long duration of the bracket bonding procedure and the high occlusal index scores at the end of treatment.

I have another concern regarding the statistical analysis. First, if the team had conducted a multivariate analysis, they could have accounted for variations among the operators. Furthermore, when we examine the effect size and the broad confidence intervals, particularly for the duration of treatment, it’s important to note that they are close to zero. This indicates that we have a low level of confidence in the data, and the true effect may, in fact, be minimal.

Finally, the lack of information about the randomisation and concealment means that the trial is at high risk of bias.  I am not saying that the trial is biased but the risk of bias is high.

Final comments

When I consider all these issues my only conclusion is that there is a great deal of uncertainty in the findings of this study.  I think that the authors, perhaps, feel the same. Hence their rather vague conclusion.

I hope that you have found this post interesting and have picked up some tips on how to read a trial publication.

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Have your say!

  1. Thank you for your great post as always. There is one main thing that makes me wonder. We have average treatment times with fixed appliances here of 28-34 months. This is superlong treatment. So we compare inefficient treatment with inefficient treatment. I feel that this may be the wrong institution to look at efficiency of treatment modalities.

  2. “When they looked at chair time. They defined this as the time it took for bonding and banding. They found that the time required to bond brackets from the mandibular incisors to the molars was 35.91 (SD=15.51) minutes for the indirect group and 58.51 (SD=25.4) minutes.”

    Is it chair time for bonding mandibular teeth only or for both arches?
    For indirect bonding, they should include the doctor’s time to do (if he does it himself), to verify (if he does not) and to approve the IB set up.

    It takes me less than 30 minutes to direct bond upper and lower arch, including prophylaxy, and etching

    • This was not clear in the text. I was not sure if it was both arches or just one at a time. Even if this was upper and lower, the time that they took was long!

  3. What about those situations when you do indirect bonding and find that 3 brackets haven’t bonded properly??? Please don’t tell me you haven’t had them!!!

  4. Thanks Kevin, I agree that clinically applicable articles are essential. Thanks for interspersing your reasoning as your analysis progressed sequentially. It is essential that we read and comprehend M&M & stats as much can be obscured with poor stats and interpretation. Understanding that overlapping confidence intervals suggests the similarities of the results have overlap and unlikely to be termed ‘significant’. Of course replication of the study and Meta-analysis may reinforce or reduce significance.
    The increased bond failure aligned with my experience of indirect bonding. Authors and journals have vested interest and bias in having their papers published, relying on an authors stats without running a couple of checks is foolhardy, their use of more modern stats and better interpretation is also highly desirable.
    I also found indirect bonding no quicker for me (no dental auxilliaries helping) so the economics in my setting did not work out positively. In other practice models it may be more efficient. There was also Dr time in setting up the bonding be it physical or digital that must be accounted for, unless all responsibility is allocated to staff to position the brackets.
    The results align with my experience, that doesn’t make it right but it ‘feels right’ to me. The conclusion contradicts my lived experince, I found indirect bonding less reilable, no discernable increase in accuracy and more Dr time consuming in my practice. I understand that different practice models to mine can make indirect bonding economically advantageous.

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