White spot lesions, plaque accumulation and salivary caries-associated bacteria in clear aligners compared to fixed orthodontic treatment. A systematic review and meta- analysis

Raghavan et al. BMC Oral Health (2023) 23:599 https://doi.org/10.1186/s12903-023-03257-8 BMC Oral Health Open Access RESEARCH White spot lesions, plaque accumulation and salivary caries-associated bacteria in clear aligners compared to fixed orthodontic treatment. A systematic review and metaanalysis Shailaja Raghavan1* , Elham S. Abu Alhaija1 , Mandeep Singh Duggal1 , Srinivasan Narasimhan2 Sadeq Ali Al-Maweri1 and Abstract Objective To analyse the available evidence regarding the incidence and severity of white spot lesions (WSLs), plaque accumulation and salivary caries-associated bacteria(SCB) in clear aligners (CA) verses conventional fixed (CF) orthodontic appliances. Methods Electronic searches of MEDLINE, Scopus, Embase, Google Scholar, Clinical trial registry, OpenGrey and ProQuest were done for all relevant studies. Eligibility criteria were; Randomized Controlled Trials and NonRandomized Studies that compared the incidence and severity of WSLs, plaque accumulation and SCB between CA and CF appliances in patients undergoing orthodontic treatment. The risk of bias(ROB) and certainty of evidence was assessed independently by two reviewers using Cochrane’s ROB and GRADEpro, respectively. Standardized mean difference (SMD) was used to estimate the effect size using STATA 17 software. Results A total of 14 studies met the eligibility criteria, and eight were suitable for meta-analysis. The qualitative results showed lower incidence and severity of WSLs, plaque accumulation, and SCB in CA group compared to CF appliances. The pooled results showed significantly lower plaque accumulation(SMD − 1.58;95%CI:-2.57,0.58;p = 0.002) in CA compared to CF appliances. Conclusions A moderate-quality evidence reveals less plaque accumulation and less SCB in CA, which might be related to the reduced incidence and severity of WSLs associated with CA when compared with CF appliances. However, the results of the present study should be interpreted with caution given the high ROB among some of the included studies as well as the marked heterogeneity across the studies. Clinical relevance For patients who can be treated with either CA or CF appliances, CA may be a better choice concerning oral health. *Correspondence: Shailaja Raghavan Full list of author information is available at the end of the article © The Author(s) 2023. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Raghavan et al. BMC Oral Health (2023) 23:599 Page 2 of 15 Registration Open Science Framework (DOI:https://doi.org/10.17605/osf.io/kcpvb). Keywords Clear aligners, White spot lesions, Plaque index, Salivary caries-associated bacteria Introduction White spot lesions (WSLs) are consequences of subsurface enamel demineralization caused by acid producing caries-associated bacteria in the plaque. WSLs manifest as chalky white opacity of enamel and is an undesirable common complication of orthodontic treatment [1]. Several studies have reported a substantial increase in the prevalence of WSLs in orthodontic patients ranging from 2 to 97% [2]. Although, it is believed that these lesions may reduce or even disappear after appliance debonding due to the remineralizing potential of saliva, [3] some of the lesions may still persist much longer [4]. The significant increase in prevalence of these lesions during fixed appliance treatment is attributed to the increase in plaque retentive areas that hinder the routine oral hygiene measures, further increasing the plaque load around the brackets. Apart from plaque accumulation, fixed orthodontic appliance induces alterations in oral microbiota; it has been reported that there are increased levels of Streptococcus mutans and Lactobacillus species in the oral cavity detected after bonding orthodontic attachments [5, 6]. Furthermore, analysis by checkerboard DNA-DNA hybridization technique has shown multi-colonization of several bacterial species including cariogenic microorganism on metallic brackets soon after bonding [7]. In addition, a recent study based on RT PCR quantification of salivary levels of caries-associated bacteria in patients with fixed orthodontic appliance revealed increased levels compared to non-orthodontic patients [8]. The increase in plaque coupled with elevation in caries-associated bacterial counts in biofilm and saliva [5] eventually reduces the pH resulting in enamel demineralization. Recently, there has been an increase in aesthetic demands among patients seeking orthodontic treatment [9]. Clear aligners (CA) are transparent removable thermoplastic trays that is believed to be safe, aesthetic, removable and comfortable orthodontic appliance. They enable patients to carry out routine oral hygiene procedures and thereby reducing the negative effects of orthodontic appliance on periodontal health [10]. However, a 2.85% overall incidence of new WSLs has been reported with the use of CA and 28% of the patients were affected by at least one new WSL considering all the assessed teeth [11]. In addition, surface area of the WSLs has been found to be large but with less mineral loss during CA treatment compared to fixed appliance treatment [12]. This can be attributed to the fact that patients are advised to wear aligners approximately 22 h a day for optimal results which interrupts the self-cleansing activities of orofacial soft tissues allowing further accumulation of plaque under the aligner [13] and hampers the cleansing, buffering and remineralizing properties of saliva. Another study reported increase in caries- causing microbes namely, Streptococcus and Lactobacillus, within 24 h of CA wear [14]. Although, many studies on the periodontal health status, incidence of WSLs and salivary caries-associated bacterial levels in patients undergoing treatment with CA and fixed orthodontic appliances have been done, there are still some controversies existing [15]. Recent findings by Shokeen et al. [16] reported that CA treatment has less negative impact on (...truncated)