Orthodontic treatment does not reduce the chance of dental decay?
We are still unsure whether providing orthodontic treatment can reduce the chance of dental decay. This new study gives us some interesting information on this question.
One long-standing belief about orthodontic treatment is that by reducing dental crowding, we may reduce the plaque accumulation that could lead to caries. However, there is no reliable evidence that dental crowding is related to caries. As a result, it does not necessarily follow that orthodontic treatment may reduce the incidence of decay.
A team of Australian investigators looked at this question in this ambitious study. Community Dentistry Oral Epidemiology published this paper.
What did they ask?
They did this study to answer this question;
“Is there an influence of orthodontic treatment on dental caries experience in a cohort of 30-year-old adults”?
What did they do?
They did a cross-sectional review of participants who had enrolled in a longitudinal study.
The study started In 1988-89 when the team screened 3925 13-year-old children who had not received orthodontic treatment. In 2005-6 they identified 1859 of the original sample and invited them to take part in this study.
At the start of the study, they collected the Dental Aesthetic Index (DAI) data on the sample of children.
When they saw them for the follow-up investigation, they collected the following data;
- Decayed missing and filled teeth (DMFT)
- Their sociodemographic status
- Information on their tooth brushing frequency, orthodontic treatment experience and their dental attendance from questionnaires.
This was a complex dataset, so they analysed this with relevant multivariate statistics that took the effect of cofounders into account.
What did they find?
They obtained data on 448 participants. This was 24% of the original sample. As a result, of this response rate, they compared the recalled sample with the original sample. They found that more of the follow-up participants were female and had both parents tertiary educated.
They presented a large amount of data. I thought that the most important findings were:
- Approximately one-third of the participants had received orthodontic treatment.
- 46% brushed their teeth twice a day
- There was no effect of orthodontic therapy on caries experience.
- Socio-demographic and dental health variables were associated with caries.
What did I think?
Firstly, this was an ambitious and complex study. As with all studies, there are some limitations. The investigators drew attention to these, and they pointed out:
- The final response rate was low. Nevertheless, I thought that they included a large number of participants. Unfortunately, there was some difference between the original sample and the final respondents and we have to consider if this could lead to bias.
- They relied on self-report data from questionnaires. This may be inaccurate.
I am also concerned about the use of the DAI. While the DAI is a good measure for the need for orthodontic treatment. It is a composite measure and does not always record crowding. For example, a person may have well-aligned arches with a large overjet. This will score high on the DAI, but they will not have crowding.
This is important because if we want to measure the relationship between crowding, orthodontic treatment and caries, we need to measure individual tooth crowding at baseline. We can then test if the crowding was related to caries at the follow-up, with or without orthodontic treatment. Unfortunately, the DAI does not have sufficient accuracy to enable this to be done for every case.
I think that this study was very interesting. However, we should think about whether the issues that I have highlighted influence the conclusions.
I feel that this study provides us with some of the best evidence that we can get on this question. The finding that dental care behaviour and socio-demographic factors are more relevant to caries experience than orthodontics is logical. As a result, I cannot help thinking that orthodontic treatment does not prevent dental caries in a population of children. However, this is still up for debate?
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