Clear aligners vs fixed appliances: which treatment option presents a higher incidence of white spot lesions, plaque accumulation and salivary caries-associated bacteria?

Abstract

Data sources

Multiple databases were searched electronically in order to find relevant studies for the meta-analysis. These included: MEDLINE, Scopus, Embase, Google Scholar, Clinical trial registry, OpenGrey and ProQuest. Two independent reviewers were used to assess the certainty of evidence and risk of bias.

Study selection

The eligibility criteria for the studies were as follows: randomized controlled trials and non-randomized studies that compared the incidence and severity of white spot lesions, plaque accumulation and salivary caries-associated bacteria between clear aligners and conventional fixed appliances in patients undergoing orthodontic treatment. In total, 14 studies met the criteria, with 8 of the studies deemed suitable for meta-analysis.

Data extraction and synthesis

Two independent reviewers carried out data extraction with a form composed of the following subheadings: Study information, Population, Intervention and control, Outcomes. The risk of bias was assessed using the ROBINS-I tool and a revised version of ROB-2, the Cochrane risk of bias tool. GRADEpro GDT software was used to assess the quality of evidence. To calculate the size of the effect of the different treatment options, the mean and standard deviation were extracted from all included studies. Heterogeneity was assessed using chi square and I² tests, with a p value below 10% being indicative of significant heterogeneity for the chi square and a value greater than 50% being indicative of significant heterogeneity for the I² tests.

Results

With regards to plaque accumulation, the effect size was measured at 3 time points: 3 months, 6 months and 12 months. At all the time points assessed within the 8 studies included in the meta-analysis, the effect size was greater for clear aligners. With regards to white spot lesions, 4 studies were available to assess the incidence of white spot lesions. Three studies reported a lower risk of developing white spot lesions in clear aligners, where one study reported no difference. As all 4 studies used different methodologies, a meta-analysis was not possible. With regards to salivary caries-associated bacteria, 2 studies reported a higher concentration of bacteria in conventional fixed appliances. Meta-analysis was not performed due to lack of studies.

Conclusions

Based on the evidence presented, clear aligners appear to be associated with less plaque accumulation and less salivary caries-associated bacteria when compared with conventional fixed appliances. Therefore, this could be related to the reduced incidence of white spot lesions in clear aligners.