Alterations of the oral microbiome in patients treated with the Invisalign system or with fixed appliances

A comparison of the alterations of oral microbiome with fixed orthodontic therapy and clear aligners: a systematic review

Aim

The oral microbiome plays a fundamental role in maintaining homeostasis of the oral cavity. In the last decade there has been an increasing use of clear aligners, which guarantee aesthetics and comfort for the patient. The aim of this work is to conduct a systematic review regarding the alterations in bacterial flora and oral health with aligner and fixed orthodontic therapy.

Design

A systematic review was conducted following the PRISMA Statement. Using the search strategy "(clear aligners OR Invisalign) AND (fixed therapy OR fixed orthodont * therapy) NOT (thermoplastic retainers) AND (oral microbiome OR oral microbiota * OR oral microbiology * OR oral health)", in the main scientific databases. Two scales were applied to assess the quality of scientific evidence: ROBINS-I and RoB 2.

Results

A total of 484 articles emerged of which 9 met our inclusion/exclusion criteria. Afterwards the application of the rating scales, 1 article was found to be at low risk of bias, 6 at moderate and 2 at serious risk of bias.

Conclusion

Both therapies cause an alteration of the oral microbiome, but the changes induced by the aligners seem to be compatible with a better oral health compared to fixed appliances.

Comparison of microbial adhesion and biofilm formation on different orthodontic aligners

INTRODUCTION

This study aimed to compare and evaluate time-dependent biofilm formation and microbial adhesion on 6 different clear aligner systems: Invisalign (Align Technology, San Jose, Calif), Clarity (3M ESPE Maplewood, Minn), ClearCorrect (Institut Straumann AG, Basel, Switzerland), Smartee (Smartee Denti-Technology, Shanghai, China), Orthero (Orthero, Istanbul, Turkey) and Graphy (Graphy Inc, Seoul, South Korea).

METHODS

Streptococcus mutans (ATCC 25175) and Lactobacillus acidophilus (ATCC 4356) were used to evaluate the microbial adhesion and biofilm formation on orthodontic clear aligners at the 0, 24, 48, 72, 96, 120, 168, and 240 hours. Two-way repeated measures analysis of variance (Greenhouse-Geisser) test and post-hoc Bonferroni T2 tests were used for statistical evaluation. The statistical significance level was set at P <0.05.

RESULTS

It was found that more bacterial formation occurred on ClearCorrect than on Smartee at 120, 168, and 240 hours (P <0.05). It was observed more biofilm formation at 168 hours on Graphy than on Smartee (P <0.05). It was found that S mutans + L acidophilus formed more biofilm at 120 and 168 hours on Graphy than on Invisalign (P <0.05).

CONCLUSIONS

Elevated biofilm formation across all materials carries substantial clinical implications. Orthodontists and patients should remain aware of the increased risk of microbial colonization with extended aligner usage.

Dynamic effects of fixed orthodontic treatment on oral health and oral microbiota: a prospective study

OBJECTIVE

This prospective clinical study examined the effects of fixed orthodontic appliances on oral hygiene and assessed changes in the oral microflora structure of orthodontic patients using high-throughput sequencing technology.

METHODS

A total of 45 patients undergoing initial fixed orthodontic treatment were recruited from three hospitals in Beijing, China. Clinical parameters and oral hygiene habits questionnaire were recorded at pre-treatment (T0) and at a 6-month follow-up (T1). Saliva samples were collected for DNA extraction, PCR amplification, 16S rRNA gene sequencing, and bioinformatics analysis. Microbial diversity and structural changes in abundance were evaluated.

RESULTS

After six months of orthodontic treatment, patients' daily brushing frequency increased (P ≤ 0.01), while the plaque index and the debris index decreased. A total of 3,344,549 valid tags were obtained from 90 saliva samples. After the six-month follow-up, the microbial diversity in patients' saliva samples increased significantly. High-throughput sequencing identified 3,662 amplicon sequence variants (ASVs), with the dominant phyla being Proteobacteria, Bacteroidota, Firmicutes, Actinobacteriota, Fusobacteriota, Patescibacteria, Campylobacterota and Spirochaetota. At the phylum level, the abundance of Firmicutes_C and Spirochaetota at T1 significantly increased compared to T0.

CONCLUSION

During fixed orthodontic treatment, although patients' oral hygiene habits improved, significant changes in the oral microbiota structure were still observed, with an increase in anaerobic and pathogenic bacteria that may potentially impact oral health.

Dynamics of the oral microbiome during orthodontic treatment and antimicrobial advances for orthodontic appliances

The oral microbiome plays an important role in human health, and an imbalance of the oral microbiome could lead to oral and systemic diseases. Orthodontic treatment is an effective method to correct malocclusion. However, it is associated with many adverse effects, including white spot lesions, caries, gingivitis, periodontitis, halitosis, and even some systematic diseases. Undoubtedly, increased difficulty in oral hygiene maintenance and oral microbial disturbances are the main factors in developing these adverse effects. The present article briefly illustrates the characteristics of different ecological niches (including saliva, soft tissue surfaces of the oral mucosa, and hard tissue surfaces of the teeth) inhabited by oral microorganisms. According to the investigations conducted since 2014, we comprehensively elucidate the alterations of the oral microbiome in saliva, dental plaque, and other ecological niches after the introduction of orthodontic appliances. Finally, we provide a detailed review of recent advances in the antimicrobial properties of different orthodontic appliances. This article will provide researchers with a profound understanding of the underlying mechanisms of the effects of orthodontic appliances on human health and provide direction for further research on the antimicrobial properties of orthodontic appliances.

Different Effects of Fixed Appliances and Clear Aligners on the Microbiome and Metabolome of Dental Plaque

OBJECTIVE

This study aimed to uncover the microbial and metabolic changes in dental plaque during orthodontic treatments with fixed appliances (FAs) and clear aligners (CAs).

MATERIALS AND METHODS

Twenty participants were grouped by the treatment modality they received, with 10 participants each in the FA and CA groups. Supragingival plaques were collected before orthodontic treatment (T0), after 1-3 months (T1) and more than 6 months (T2) of orthodontic treatment. 16S rRNA gene sequencing and liquid chromatography-tandem mass spectrometry were employed to analyse the plaque samples.

RESULTS

No significant change was observed in the alpha and beta diversity at different time points and between the two treatment modalities. The relative abundance of genera Veillonella, Mogibacterium and unclassified_c__Actinobacteria, and species Actinomyces massiliensis, Prevotella pallens and Prevotella jejuni experienced the most significant changes. The most differential metabolites were amino acids, nucleosides and organoheterocyclic compounds. Compared to T0, downregulation of nucleotide metabolism at T1 and upregulation of amino acid metabolism at T2 were found in the FA group. Compared with the FA group, the CA group experienced metabolite enrichment in several immune pathways at T1, while linoleic acid metabolism, riboflavin metabolism and nucleotide metabolism were downregulated at T2 in the CA group. Significant correlations were identified between most differential plaque microorganisms and metabolites.

CONCLUSION

This study implied that exposure to FAs for more than 6 months resulted in the accumulation of oral disease-related bacteria in dental plaque and a metabolic shift towards a cariogenic state, whereas CAs could lead to a transient proinflammatory state.

Effects of clear aligners and traditional removable appliances on oral microbiome in mixed dentition: a comparative study

BACKGROUND

This prospective study aims to investigate the comparative effects of clear aligners (CA) and traditional removable appliances (RA) on the cariogenic risk of patients in mixed dentition, focusing on the oral microbiome.

METHODS

25 children were included and assigned into CA and RA groups. Supragingival plaque and saliva samples were collected, and clinical parameters including Decay-missing-filled teeth index (DMFT), Plaque Index (PI) and Gorelick Index (GI) were recorded before treatment (T0) and after 6-month follow-up (T1). DNA was extracted from supragingival plaque and saliva and analyzed via 16S rDNA gene sequencing.

RESULTS

Clinical parameters showed no statistically significant difference between groups at each time point or within group over time (p > 0.05). In both RA and CA groups, saliva exhibited significantly higher alpha diversity compared to supragingival plaque at T1, as indicated by the significantly higher Chao1 and Shannon indexes (p < 0.05). Regarding beta diversity, significant difference was observed in saliva and supragingival plaque samples between T0 and T1 within group RA (p < 0.05, Adonis), whereas no such significance was noted in the CA group (p > 0.05, Adonis). At the genus level, Lactobacillus exhibited a statistically significant increase in saliva and supragingival plaque of group RA from T0 to T1 (p < 0.05), and an increasing trend in the group CA without statistical significance (p > 0.05). At T1, Lactobacillus levels were comparable between groups, whereas species-level analysis revealed distinct cariogenic species.

CONCLUSION

Both clear aligners and traditional removable appliances resulted in elevated cariogenic risk of patients in mixed dentition at the microbial level. Distinct alterations in cariogenic species were observed to be induced by various orthodontic appliances.

Incidence, severity, and risk factors for white spot lesions in adolescent patients treated with clear aligners

OBJECTIVES

This study was aimed to clarify the incidence, severity, and clinical risk factors for white spot lesions (WSLs) in adolescent patients treated with clear aligners.

METHODS

Pre-treatment and post-treatment intraoral photographs of 203 adolescent patients undergoing clear aligner therapy were retrospectively evaluated to assess the occurrence and severity of WSLs. Information on patients' general oral condition and orthodontic treatment was collected from clinical medical documents, retrospective questionnaires, and ClinCheck® software. Independent risk factors and model performance were determined by multivariate logistic regression and receiver operating characteristic curve analysis.

RESULTS

Thirty-five percent of adolescent patients developed WSLs during clear aligner treatment. Logistic regression analysis revealed that the presence of WSLs before treatment (OR 2.484, 95% CI 1.245-4.957), frequency of drinking carbonated beverages (OR 1.508, 95% CI 1.045-2.177), and number of anterior attachments (OR 2.192, 95% CI 1.502-3.198) were risk factors for the occurrence of WSLs in adolescent patients treated with clear aligners (P < .05), whereas the number of times they brushed each day (OR 0.656, 95% CI 0.454-0.947) and frequency of aligner cleaning after eating while wearing them (OR 0.611, 95% CI 0.433-0.861) were protective factors against WSLs (P < .05).

CONCLUSIONS

The incidence of WSLs was high in adolescent patients treated with clear aligners. Few brushings each day, pre-treatment WSLs, a high frequency of drinking carbonated beverages, a low frequency of aligner cleaning after eating while wearing them, and a high number of anterior attachments are strongly associated with the development of WSLs in adolescent patients treated with clear aligners.

The Effect of Nanoparticles Against Streptococcus mutans in the Orthodontic Primer Used for Aligner Attachment: An In Vitro Study

Objective This study investigates the antimicrobial properties of silver (1%) and chitosan (1%) nanoparticles against Streptococcus mutans (S. mutans) when added to an orthodontic primer used for aligner attachments. While aligner treatments are becoming increasingly popular for their aesthetics and convenience, their attachments can create retention sites for bacteria, potentially leading to white spot lesions (WSLs). This in vitro study aims to address this issue by enhancing the antimicrobial efficacy of aligner primers. Methodology Thirty freshly extracted teeth were classified into the following three groups: Group A with the standard primer, Group B with chitosan nanoparticles mixed in the primer, and Group C with silver nanoparticles mixed in the primer. The samples were incubated with S. mutans and bacterial colonies were counted at 12, 24, 48, and 72 hours. Results The results showed a significant reduction in colony-forming units (CFUs) in the groups with nanoparticles compared to the control group, with silver nanoparticles exhibiting a higher antimicrobial effect than chitosan. Conclusions This study suggests that incorporating silver nanoparticles into orthodontic primers can effectively reduce bacterial growth, potentially improving oral hygiene and reducing the risk of WSLs in patients undergoing aligner treatment.

The oral microbiota and periodontal health in orthodontic patients

The oral microbiota develops within the first 2 years of childhood and becomes distinct from the parents by 4 years-of-age. The oral microbiota plays an important role in the overall health/symbiosis of the individual. Deviations from the state of symbiosis leads to dysbiosis and an increased risk of pathogenicity. Deviations can occur not only from daily life activities but also from orthodontic interventions. Orthodontic appliances are formed from a variety of biomaterials. Once inserted, they serve as a breeding ground for microbial attachment, not only from new surface areas and crevices but also from material physicochemical interactions different than in the symbiotic state. Individuals undergoing orthodontic treatment show, compared with untreated people, qualitative and quantitative differences in activity within the oral microbiota, induced by increased retention of supra- and subgingival microbial plaque throughout the treatment period. These changes are at the root of the main undesirable effects, such as gingivitis, white spot lesions (WSL), and more severe caries lesions. Notably, the oral microbiota profile in the first weeks of orthodontic intervention might be a valuable indicator to predict and identify higher-risk individuals with respect to periodontal health and caries risk within an otherwise healthy population. Antimicrobial coatings have been used to dissuade microbes from adhering to the biomaterial; however, they disrupt the host microbiota, and several bacterial strains have become resistant. Smart biomaterials that can reduce the antimicrobial load preventing microbial adhesion to orthodontic appliances have shown promising results, but their complexity has kept many solutions from reaching the clinic. 3D printing technology provides opportunities for complex chemical syntheses to be performed uniformly, reducing the cost of producing smart biomaterials giving hope that they may reach the clinic in the near future. The purpose of this review is to emphasize the importance of the oral microbiota during orthodontic therapy and to use innovative technologies to better maintain its healthy balance during surgical procedures.

Longitudinal Microbiome Changes in Supragingival Biofilm Transcriptomes Induced by Orthodontics

INTRODUCTION

Common oral diseases are known to be associated with dysbiotic shifts in the supragingival microbiome, yet most oral microbiome associations with clinical end points emanate from cross-sectional studies. Orthodontic treatment is an elective procedure that can be exploited to prospectively examine clinically relevant longitudinal changes in the composition and function of the supragingival microbiome.

METHODS

A longitudinal cohort study was conducted among 24 adolescent orthodontic patients who underwent saliva and plaque sampling and clinical examinations at time points: before fixed appliance bonding and at 1, 6, and 12 wk thereafter. Clinical indices included bleeding on probing (BOP), mean gingival index (GI), probing depths (PDs), and plaque index (PI). To study the biologically (i.e., transcriptionally) active microbial communities, RNA was extracted from plaque and saliva for RNA sequencing and microbiome bioinformatics analysis. Longitudinal changes in microbiome beta diversity were examined using PERMANOVA tests, and the relative abundance of microbial taxa was measured using Kruskal-Wallis tests, Wilcoxon rank-sum tests, and negative binomial and zero-inflated mixed models.

RESULTS

Clinical measures of oral health deteriorated over time-the proportion of sites with GI and PI ≥1 increased by over 70% between prebonding and 12 wk postbonding while the proportion of sites with PD ≥4 mm increased 2.5-fold. Streptococcus sanguinis, a health-associated species that antagonizes cariogenic pathogens, showed a lasting decrease in relative abundance during orthodontic treatment. Contrarily, caries- and periodontal disease-associated taxa, including Selenomonas sputigena, Leptotrichia wadei, and Lachnoanaerobaculum saburreum, increased in abundance after bonding. Relative abundances of Stomatobaculum longum and Mogibacterium diversum in prebonding saliva predicted elevated BOP 12 wk postbonding, whereas Neisseria subflava was associated with lower BOP.

CONCLUSIONS

This study offers insights into longitudinal community and species-specific changes in the supragingival microbiome transcriptome during fixed orthodontic treatment, advancing our understanding of microbial dysbioses and identifying targets of future health-promoting clinical investigations.

KNOWLEDGE TRANSFER STATEMENT

Bonding braces was associated with subsequent changes in the oral microbiome characterized by increases in disease-associated species, decreases in health-associated species, and worsened clinical measures of oral health.

Microbial Changes in the Periodontal Environment Due to Orthodontic Appliances: A Review

Orthodontic appliances significantly influence the microbiological dynamics within the oral cavity, transforming symbiotic relationships into dysbiotic states that can lead to periodontal diseases. This review synthesizes current findings on how orthodontic treatments, particularly fixed and removable appliances, foster niches for bacterial accumulation and complicate oral hygiene maintenance. Advanced culture-independent methods were employed to identify shifts toward anaerobic and pathogenic bacteria, with fixed appliances showing a more pronounced impact compared to clear aligners. The study underscores the importance of meticulous oral hygiene practices and routine dental monitoring to manage these microbial shifts effectively. By highlighting the relationship between appliance type, surface characteristics, treatment duration, and microbial changes, this review aims to enhance dental professionals' understanding of periodontal risks associated with orthodontic appliances and strategies to mitigate these risks. The findings are intended to guide clinicians in optimizing orthodontic care to prevent plaque-associated diseases, ensuring better periodontal health outcomes for patients undergoing orthodontic treatment.

Effects of orthodontic aligners on 24-hour masseter muscle activity: a multiple-day electromyographic study

OBJECTIVE

This study aimed to assess the effects of aligners on masseter muscle activity by using an electromyographic device in the home environment.

METHODS

The study was performed on healthy patients who required orthodontic treatment. Three different 24 h-EMG recording sessions were performed in different conditions: without aligners, with passive aligners, and with active aligners. The non-functional MMA work index (nfMMA-WI) and the non-functional MMA time index (nfMMA-TI) for both awake and sleep hours were assessed. ANOVA test was used to compare the average activity during the three recording conditions.

RESULTS

On average, a total recording time of 204.7 ± 7.9 hours were provided for each patient. For most patients, ANOVA test showed an absence of significant differences between the recording sessions.

CONCLUSIONS

The impact of our results is not negligible: clinicians can find remarkable support to the hypothesis that the use of aligners affects the MMA only in a minority of subjects.

Microbiological Analysis of Plaque and Its Composition in Three Patient Groups under Different Orthodontic Treatments

BACKGROUND

This article analyzes differences in microbiological parameters and periodontal health conditions among three patient groups: those undergoing conventional orthodontic treatment with fixed appliances, patients undergoing orthodontic treatment with clear aligners, and a control group receiving no treatment.

MATERIALS AND METHODS

In this study, 60 patients were enrolled. The microbiological analysis employed a qualitative and semi-quantitative methodology of bacterial morphotype analysis.

RESULTS

The analyses revealed a significant difference in favor of clear oral and periodontal health aligners. This could be attributed to better bacterial biofilm removal and reduced mechanical stress on the periodontal ligament, factors facilitated by the ease of clear aligner removal. Significant differences (p-value < 0.05) were observed for the Full-Mouth Plaque Score, Full-Mouth Bleeding Score, Plaque Index, and periodontal health assessment measurements.

CONCLUSIONS

Although overall hygiene appears to be improved in patients in the aligners group compared to those treated with conventional orthodontic appliances, there are no statistically significant results regarding plaque composition. Microbiological aspects will be further addressed using more specific techniques in the follow-up of this research.

Comparative characterization of supragingival plaque microbiomes in malocclusion adult female patients undergoing orthodontic treatment with removable aligners or fixed appliances: a descriptive cross-sectional study

Objectives

This study aimed to explore the effects of removable aligners and fixed appliances on the supragingival bacterial communities in adult female patients undergoing orthodontic treatment.

Methods

Supragingival plaque samples from 48 female individuals underwent microbiome analysis (16S rRNA gene sequencing) using PacBio Sequel sequencing. The study included 13 adults without orthodontic treatment needs as the control group (Group C), and 35 patients with comparable initial orthodontic conditions who received treatment at a university clinic in Beijing, China. The treatment involved either traditional fixed brackets (Group B, n = 17) or Invisalign® aligners (Group AT, n = 18). Bioinformatics methods were used for data analysis.

Results

From the 48 plaque samples, a total of 334,961 valid reads were obtained, averaging 6,978 sequences per sample. The 16S rDNA sequences were classified into 25,727 amplicon sequence variants (ASVs). Significant variances in alpha and beta diversity among the groups were noted. Group B microbiome exhibited an increased presence of Gram-negative bacteria. At the phylum level, Actinobacteriota was significantly more prevalent in Group C samples, while Bacteroidota was enriched in Group B samples. Family-level relative abundance analysis showed a notable increase in Saccharibacteria (formerly TM7) and Prevotellaceae in Group B. Genus-level analysis revealed a significant rise in Lautropia in Group AT. Fixed orthodontic appliances were linked to oral microbiome changes, notably an enhanced relative abundance of anaerobes, including periodontal pathogens.

Conclusion

The observation points to the impact of orthodontic appliance on the oral microbial community, highlighting the difference between traditional braces (Group B) and clear aligners (Group AT)in terms of the predominance of anaerobic and gram negative bacteria. This emphasizes the importance of considering the microbiological effects when choosing orthodontic appliance and underscores the need for tailored oral hygiene practices for individuals undergoing these treatments. This research might provide insights that could assist in the development of innovative cleaning techniques and antibacterial materials.

The Influence of Orthodontic Treatment on Periodontal Health between Challenge and Synergy: A Narrative Review

By correctly repositioning teeth, orthodontic therapy improves both the function and appearance of an occlusion. The relationship between teeth and the tissues that surround and support them significantly influences these alterations. With ever more adults seeking orthodontic care, orthodontists are increasingly seeing patients with periodontal issues. Concerns about the patient's appearance, such as uneven gingival margins or functional issues caused by inflammatory periodontal diseases, should be accounted for when designing orthodontic treatment plans. Furthermore, orthodontics may increase the chances of saving and recovering a degraded dentition in cases of severe periodontitis. Today, general dentists, dontists, and orthodontists play integrative roles that enable them to achieve the best possible results for their patients. This review will improve the results of interdisciplinary treatments and increase cooperation between dental specialists by drawing attention to the essential connection between orthodontics and periodontics in regular clinical practice.

Salivary microbiomes vary among orthodontic appliances and associate with clinical periodontal parameters

OBJECTIVE

To investigate the salivary bacterial communities during the first 6-month orthodontic treatment with Clear Aligners (CA) and Fixed Appliances (FA), and its correlation with clinical periodontal parameters.

MATERIALS AND METHODS

Saliva and periodontal parameters were sampled from individuals wearing CA or FA before treatment (T0), and after 3- (T3) and 6-month (T6) treatments. Salivary bacterial communities characterized based on the 16S rRNA V3-V4 region were compared between FA and CA and correlated with clinical periodontal parameters.

RESULTS

Probing Depth (PD) significantly increased at T6 in the FA group versus T0, whereas it remained stable in the CA group. The Shannon and Pielou indices were significantly higher in the FA group and significantly positively correlated with periodontal inflammation parameters. β-diversity analysis revealed distinct communities between the FA group and CA group at T6. The relative abundances of 3 genera and 15 species were significantly higher in the FA group. Among the above appliance-type related taxa, bacterial genera Selenomonas, Stomatobaculum, Olsenella and Faecalicoccus and bacterial species Selenomonas_sputigena, Dialister_invisus, Olsenella_profus, Prevotella_buccae, Cryptobacterium_curtum and Clostridium_spiroforme were significantly positively associated with periodontal parameters.

CONCLUSIONS

Orthodontic treatments trigger appliance-related salivary bacterial communities, highlighting the importance of developing appliance-orientated periodontal strategies during orthodontic treatments. Salivary bacterial communities harboured by patients wearing FA possess higher bacterial parameters which were associated with increasing PD, PI and Gingival Index.

Periodontal health status, oral microbiome, white-spot lesions and oral health related to quality of life-clear aligners versus fixed appliances: A systematic review, meta-analysis and meta-regression

Objective

: Assess and evaluate the different indicators of oral health-related quality of life (OHRQoL) among patients treated with clear aligners (CAs) versus those treated with conventional fixed orthodontics (FAs).

Methods

: An electronic search was performed on the database is Web of Science, Scopus, and Embase databases. Randomized and non-randomized control trials, cross-sectional, prospective cohort and retrospective trials were included. Quality was assessed with risk of bias tool and risk of bias in non-randomised studies. Meta-analyses were performed with random effects models, estimating the standardized and non-standardized mean differences, odds ratio and risk ratio as the measure of effect. The effect on time was determined using a meta-regression model.

Results

: Thirty one articles were included in the qualitative synthesis and 17 in the meta-analysis. CAs had a significantly lower negative impact on QoL, with an "important" effect size, while the influence of time was not significant. Periodontal indicators plaque index (PI), gingival index (GI), probing depth (PD), and bleeding on probing show significantly better values in patients treated with CAs, with moderate to large effect sizes. PI and GI have a significant tendency to improve over time. In microbiological indicators, CAs present a lower biofilm mass without differences in the percentage of patients with high counts of Streptococcus mutans and Lactobacilli bacteria. The risk of white spot lesion onset is ten times lower in carriers of CAs.

Conclusions

: Patients wearing CAs show better periodontal indicators, less risk of white spot development, less biofilm mass and a better QoL than patients with FAs.

In vitro evaluation of a novel fluoride-coated clear aligner with antibacterial and enamel remineralization abilities

OBJECTIVE

To investigate the antibacterial and enamel remineralization performances as well as physicochemical properties and biocompatibility of a fluoride-coated clear aligner plastic (FCAP).

MATERIALS AND METHODS

FCAP and normal clear aligner plastic (CAP) was bought from the manufacturer (Angelalign Technology Inc, China). The FCAP was observed under scanning electron microscopy. Its element composition, resistance to separation, contact angle, and protein adhesion performance were characterized. Colony-forming unit (CFU) count and 3-(4,5)-dimethylthiazol(-z-y1)-3,5-diphenyltetrazolium bromide (MTT) assay were used to evaluate the antibacterial ability of Streptococcus mutans. Fluoride release-recharge patterns were obtained. Apatite formation was evaluated after immersing FCAP in artificial saliva. Enamel remineralization capability was evaluated in the demineralization model (immersing samples in demineralization solution for 36 h) and pH cycling model (immersing samples in demineralization solution and remineralization solution in turns for 14 days). Cell Counting Kit-8 (CCK-8) and live/dead cell staining kits were used for cytotoxicity assay.

RESULTS

The FCAP showed uniformly distributed fluoride and did not compromise protein adhesion performance. CFU count (5.47 ± 0.55 for CAP, 3.63 ± 0.38 for FCAP) and MTT assay (0.41 ± 0.025 for CAP, 0.28 ± 0.038) indicated that the FCAP had stronger antibacterial activity compared with normal CAP (P < 0.05 for both evaluations). The FCAP could release fluoride continuously for 14 days and could be recharged after immersing in NaF solution. The FCAP could induce the formation of hydroxyapatite in artificial saliva and could reduce the microhardness decrease, color change, and mineral loss of enamels in both two models (P < 0.05 for all evaluations). CCK-8 and live/dead cell staining analyses showed that the coating did not compromise the biocompatibility of the clear aligner (P > 0.05 for CCK-8 evaluation).

CONCLUSIONS

The FCAP had antibacterial, fluoride recharge, and enamel remineralization abilities while it did not compromise physicochemical properties and biocompatibility.

CLINICAL RELEVANCE

The FCAP has the potential to prevent enamel demineralization during clear aligner treatment.

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

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 Non-Randomized 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.

REGISTRATION

Open Science Framework (DOI: https://doi.org/10.17605/osf.io/kcpvb ).

Microbiome and metabolome associated with white spot lesions in patients treated with clear aligners

White spot lesions (WSLs) have long been a noteworthy complication during orthodontic treatment. Recently, an increasing number of orthodontists have found that adolescents undergoing orthodontic treatment with clear aligners are at a higher risk of developing WSLs. The oral microbiota and metabolites are considered the etiologic and regulatory factors of WSLs, but the specific impact of clear aligners on the oral microbiota and metabolites is unknown. This study investigated the differences in the salivary microbiome and metabolome between adolescents with and without WSLs treated with clear aligners. Fifty-five adolescents (aged 11-18) with Invisalign appliances, 27 with and 28 without WSLs, were included. Saliva samples were analyzed using 16S rRNA gene sequencing and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS); the data were further integrated for Spearman correlation analysis. The relative abundances of 14 taxa, including Actinobacteria, Actinomycetales, Rothia, Micrococcaceae, Subdoligranulum, Capnocytophaga, Azospira, Olsenella, Lachnoanaerobaculum, and Abiotrophia, were significantly higher in the WSL group than in the control group. Metabolomic analysis identified 27 potential biomarkers, and most were amino acids, including proline and glycine. The metabolites were implicated in 6 metabolic pathways, including alanine, aspartate and glutamate metabolism; glycine, serine and threonine metabolism; and aminoacyl-tRNA biosynthesis. There was a correlation between the salivary microbial and metabolomic datasets, reflecting the impact of clear aligners on the metabolic activity of the oral flora. A concordant increase in the levels of Lachnoanaerobaculum, Rothia, Subdoligranulum and some amino acids had predictive value for WSL development. In summary, when adolescents undergo long-term clear aligner therapy with poor oral hygiene habits, clear aligners can disrupt the balance of the oral microecosystem and lead to oral microbiota dysbiosis, thereby increasing the risk of developing WSLs. Our findings might contribute to the understanding of the pathogenesis of WSLs and provide candidate biomarkers for the diagnosis and treatment of WSLs associated with clear aligners.

Antibacterial and fluorescent clear aligner attachment resin modified with chlorhexidine loaded mesoporous silica nanoparticles and zinc oxide quantum dots

OBJECTIVES

To develop an antibacterial and fluorescent clear aligner attachment resin via the incorporation of chlorhexidine loaded pore-expanded mesoporous silica nanoparticles (CHX@pMSN) and amino-silane functionalized zinc oxide quantum dots (aZnO_QDs), and to evaluate its antibacterial activity, fluorescence capability, esthetic properties, mechanical performance and biocompatibility.

METHODS

CHX@pMSN and aZnO_QDs were incorporated into the commercial resin composites (Filtek Z350 XT, 3M) at different mass fractions, control group: Filtek; fluorescent attachment resin (FAR): Filtek + 3 wt% aZnO_QDs; antibacterial and fluorescent attachment resin (AFAR)-1: Filtek + 3 wt% aZnO_QDs + 1 wt% CHX@pMSN; AFAR-2: Filtek + 3 wt% aZnO_QDs + 3 wt% CHX@pMSN; AFAR-3: Filtek + 3 wt% aZnO_QDs + 5 wt% CHX@pMSN. CHX release, antibacterial activity, fluorescence capability, color change, stain resistance, degree of conversion, depth of cure, polymerization shrinkage, water sorption and solubility, softening in solvent, flexural strength, flexural modulus, shear bond strength, and cytotoxicity were evaluated comprehensively.

RESULTS

CHX could be continuously released from the AFAR groups for up to 30 days. CFU, MTT, lactic acid production, SEM and CLSM evaluation showed AFAR-2 and AFAR-3 could effectively inhibit S. mutans biofilms even after 1-month aging. Only AFAR-3 showed clinically perceptible color change and all the experimental groups were not more susceptible to staining. AFAR-1 and AFAR-2 could suppress polymerization shrinkage and enhance the resistance to degradation without compromising other properties, including degree of conversion, water sorption and solubility, flexural strength, flexural modulus, and shear bond strength. Depth of cure of all the four experimental groups was significantly decreased (p < 0.05) but still within the ISO standard. CCK-8 assay and live/dead cell staining denied the cytotoxicity of experimental resins. Fluorescence intensity tests showed that FAR and AFAR-2 could emit strong yellowish fluorescence under the excitation of ultraviolet for up to six months.

CONCLUSIONS

AFRA-2 possessed long-term antibiofilm activity, strong fluorescence capability and satisfying biocompatibility without compromising esthetic and mechanical properties. This study proposed a new strategy for reducing bacteria accumulation around the attachment, which is also promising in helping orthodontists to remove the attachment thoroughly and precisely.

Effect of an enzyme-containing mouthwash on the dental biofilm and salivary microbiome in patients with fixed orthodontic appliances: a randomized placebo-controlled pilot trial

BACKGROUND

Mouthwashes containing oral antiseptics or enzymes are suggested suitable for controlling biofilm accumulation in patients with fixed appliances and thereby limiting unwanted side effects during the orthodontic treatment.

OBJECTIVES

To evaluate the effect of an enzyme-based mouthwash on the amount of dental biofilm and the composition of the salivary microbiome in patients undergoing treatment with fixed orthodontic appliances.

TRIAL DESIGN

Randomized double-blind placebo-controlled trial.

MATERIAL AND METHODS

In total, 35 young adolescents (14-18 years) under treatment with fixed appliances were consecutively enrolled and randomly allocated to an experimental or a placebo group by opening a computer-generated numbered envelope. The subjects were instructed to rinse twice daily during an intervention period of 8 days with experimental mouthwash or placebo without active enzymes. Unstimulated whole saliva samples were collected at baseline and after 8 days. The participants and examiner were blinded for the allocation. The primary outcome was the Orthodontic Plaque Index (OPI) and the secondary was the composition of the salivary microbiome.

RESULTS

In total, 28 adolescents (21 females and 7 males) completed the trial and there were no differences in age, clinical, or microbial findings between the test (n = 14) and the placebo group (n = 14) at baseline. We found a decreased OPI in the test group after 8 days and the difference was statistically significant compared with the placebo group (P < 0.05). There were no significant treatment effects on the richness and global composition of the salivary microbiome.

HARMS

In total, one participant in the test group claimed nausea and abandoned the project. In total, two participants did not like the taste of the mouthwash but used it as instructed. No other adverse events or side effects were reported.

LIMITATIONS

Short-term pilot trials may by nature be sensitive for selection and performance biases and are not designed to unveil persisting effects.

CONCLUSION

Daily use of enzyme-containing mouthwash reduced the amount of dental biofilm in adolescents under treatment with the fixed orthodontic appliances, without affecting the composition of the salivary microbiota.

ETHICAL APPROVAL

Approved by the Regional Ethical Board, Lund, Sweden (Dnr 2020-05221).

CLINICAL TRIAL REGISTRATION

NCT05033015.

Accuracy of additive manufacturing in stomatology

With the rapid development of the three-dimensional (3D) printing technology in recent decades, precise and personalized manufacturing has been achieved gradually, bringing benefit to biomedical application, especially stomatology clinical practice. So far, 3D printing has been widely applied to prosthodontics, orthodontics, and maxillofacial surgery procedures, realizing accurate, efficient operation processes and promising treatment outcomes. Although the printing accuracy has improved, further exploration is still needed. Herein, we summarized the various additive manufacturing techniques and their applications in dentistry while highlighting the importance of accuracy (precision and trueness).

Semaphorin 3A protects against alveolar bone loss during orthodontic tooth movement in mice with periodontitis

OBJECTIVE

This study investigated the effect of local semaphorin 3A (Sema3A) administration on alveolar bone loss during OTM in a mouse model of periodontitis.

BACKGROUND

Orthodontic tooth movement (OTM) for patients with periodontal disease is known to increase the risk of exacerbating alveolar bone loss due to inflammation of the periodontal tissue. However, its mechanism of action and prevention remains unclear.

METHODS

Mice (male 7-8 weeks old, C57BL/6J, n = 12) were divided into six groups: untreated group (control), without OTM and recovered from induced periodontitis (RP), with OTM and administered PBS or Sema3A to the gingiva after induced periodontitis (VehPO, SemaPO), with OTM and administered PBS or Sema3A to the gingiva without periodontitis induction (VehNO, SemaNO). Samples were collected on 14 days, and bone loss, histological analysis, cytokine production level, and tooth movement were assessed. Cultured human periodontal ligament (hPDL) cells were stimulated with lipopolysaccharide (LPS) and compressive force (CF), and mRNA expression levels of Sema3A and its receptors were analyzed.

RESULTS

The bone loss was significantly lower in the SemaPO group than in the VehPO group. The number of TRAP-positive cells in the SemaPO group was significantly lower than that in the VehPO group and was at the same level as that in the control group. The receptor activator of nuclear factor (NF)-kB-ligand/osteoprotegerin (RANKL/OPG) ratio and the levels of proinflammatory cytokines, including interleukin (IL)-1β, IL-6, IL-17, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ, in the gingival tissues were significantly lower in the SemaPO group than in the VehPO group. Additionally, Sema3A mRNA expression in hPDL cells was significantly decreased by co-stimulation with LPS and CF compared with that in the control group. Finally, the distance moved (dist.) and the mesial tipping angle (θ) was significantly smaller in the SemaPO group than in the VehPO group and was not significantly different from that of VehNO.

CONCLUSION

Pathological alveolar bone loss exacerbated by OTM in periodontitis might be prevented by local administration of Sema3A without inhibiting OTM.

Effect of Orthodontic Appliances on the Oral Environment and Microbiome

Orthodontic treatment is an appliance-intensive endeavor, where an array of mechanical devices is used to bring about tooth movement. By virtue of remaining in close proximity to the enamel, gingiva and periodontal ligament intra-orally over a prolonged period of time, orthodontic appliances have a significant impact on the paradental tissues, oral environment and oral microbiome. Orthodontic appliances by acting as anchors for biofilm and plaque formation, accumulate bacteria and other micro-organisms in amounts unfavorable for maintenance of healthy equilibrium. The resulting loss of balance in the oral microbiome causes dysbiosis which manifests clinically as increased enamel demineralization, dental caries and periodontal disease. Mechanical removal of the accumulated plaque by maintaining rigorous oral hygiene has been proven to be the single most important factor to mitigate the harmful effects of dysbiosis. This review investigates how each of the various components of the orthodontic appliances, different types of appliances and unique surface properties of biomaterials have contributory effects at the interface of orthodontic biomaterials and oral biology. The information thus obtained will be critical in instituting the best diagnostic and therapeutic measures at the clinical level. It will also be instrumental in devising improvements and providing new directions for future research in general and precision orthodontics in particular.

Pathophysiology of Demineralization, Part II: Enamel White Spots, Cavitated Caries, and Bone Infection

PURPOSE OF REVIEW

Compare noninfectious (part I) to infectious (part II) demineralization of bones and teeth. Evaluate similarities and differences in the expression of hard tissue degradation for the two most common chronic demineralization diseases: osteoporosis and dental caries.

RECENT FINDINGS

The physiology of demineralization is similar for the sterile skeleton compared to the septic dentition. Superimposing the pathologic variable of infection reveals a unique pathophysiology for dental caries. Mineralized tissues are compromised by microdamage, demineralization, and infection. Osseous tissues remodel (turnover) to maintain structural integrity, but the heavily loaded dentition does not turnover so it is ultimately at risk of collapse. A carious tooth is a potential vector for periapical infection that may be life-threatening. Insipient caries is initiated as a subsurface decalcification in enamel that is not detectable until a depth of ~400μm when it becomes visible as a white spot. Reliable detection and remineralization of invisible caries would advance cost-effective wellness worldwide.

Evaluation of biofilm formation on different clear orthodontic retainer materials

Aim:

To assess the chemical composition and oral biofilm formation on different types of commercially available clear orthodontic retainer materials (CORM).

Materials and Methods:

Four types of CORM commercially available were used (Clear advantage series I (CAS1), Clear advantage series II (CAS2), Endure (ES), and CENTRI FORM-clear rigid material (CFCRM)). Circular samples (12 mm diameter) of each CORM were prepared for (n = 40). Unstimulated saliva from twenty volunteers was collected. Fourier Transformation Infrared Spectroscopy (FTIR) was used for the evaluation of the chemical composition of CORM. For the quantitative assessment of oral biofilm formation, samples of each CORM were incubated for twenty-four hours, and crystal violet assay (CVA) was utilized. The degree of absorbance was measured using a spectrophotometer at 570 nm. For qualitative evaluation of oral formation, the samples of each CORM were incubated for 24 hours, and viable biofilm cells stained by acridine orange were examined under a fluorescent microscope.

Results:

FTIR findings showed that CAS2 was made of polypropylene and ES is made of polyvinyl chloride, while others were made of co-polyester. CVA results confirmed that CAS2 showed the lowest biofilm formation, which differs significantly compared to CAS1, CFCRM, and ES. No significant difference in biofilm formation was detected between CAS1, CFCRM, and ES. Viable biofilm cells staining by acridine orange showed that CAS2 demonstrated smaller microcolonies of viable biofilm cells compared with CAS1, CFCRM, and ES, which confirmed the result obtained by CVA.

Conclusions:

CAS2 showed anti-microbial activities with a decrease the in vitro biofilm formation, which may be related to its chemical composition.

Taxonomic Analysis of Oral Microbiome during Orthodontic Treatment

Background

Orthodontic appliances induce significant changes in the oral microbiome, but this shift in microbial composition has not been well established by the available evidence yet.

Objectives

To perform a systematic review of existing literature in order to assess the taxonomic microbial changes in orthodontic patients during Fixed Appliance Treatment (FAT) and Clear Aligner Treatment (CAT), using next-generation sequencing (NGS) technique of the bacterial 16S rRNA gene. Search Methods and Selection Criteria. The search for articles was carried out in PubMed, including articles published in English until May 2021. They included every human study report potentially relevant to the review. Data Collection and Analysis. After duplicate study selection and data extraction procedures according to the PICOS scheme, the methodological quality of the included papers was assessed by the Swedish Council on Technology Assessment in Health Care Criteria for Grading Assessed Studies (SBU) method.

Results

The initial search identified 393 articles, 74 of which were selected by title and abstract. After full-text reading, six articles were selected according to inclusion criteria. The evidence quality for all the studies was moderate.

Conclusions

Orthodontic treatment seems to transiently affect the composition of subgingival microbiome, although not salivary, maintaining a stable microbial diversity. Different results were found in the shift of microbiome between plaque and saliva, depending on the type of orthodontic treatment. This review should be interpreted with some caution because of the number, quality, and heterogeneity of the included studies.

Patient First: Surgery First and More

INTRODUCTION

The success of surgery first approach has been defined by the number of advantages offered and is definitively determined by the satisfaction of the patients themselves. The strength of this protocol resides in its philosophy that puts the patient at the center of the whole diagnostic-therapeutic process. The compliance of the patient, its happiness and comfort are the best guarantee of a good final results. While pursuing this philosophy we have wondered whether there was way to increase the comfort of surgery first approach even more and to make it even more appealing for the patients. For these reasons, we have decided to work on a preliminary protocol in order to reduce or even eliminate the use of orthodontic braces and wires during perioperative stages. Materials and Methods: No orthodontic braces or wires are bonded on the teeth before surgery. Intraoperatory intermaxillary fixation (IMF) is carried out with the use of IMF screws which are positioned at the beginning of the operation on the edge between keratinized and nonkeratinized gingiva. Once the osteotomies are performed IMF with IMF screws is carried out on the planned occlusion with the use of surgical splints.Discussion and Conclusions: In selected cases the postsurgical orthodontic treatment can be carried out with the use of clear aligners, completely eliminating the need of braces and wires with an additional level of comfort.

Assessment of the effect of vacuum-formed retainers and Hawley retainers on periodontal health: A systematic review and meta-analysis

Background

Recently, increasing attention has been paid to the periodontal health of orthodontic patients in the maintenance stage in clinical practice. The focus of this meta-analysis was to compare the effects of vacuum-formed retainers (VFR) and Hawley retainers (HR) on periodontal health, in order to provide a reference for clinical selection.

Methods

From the establishment of the database until November 2020, a large number of databases were searched to find relevant randomized control trials, including the Cochrane Library databases, Embase, PubMed, Medline via Ovi, Web of Science, Scopus, Grey Literature in Europe, Google Scholar and CNKI. Related literature was manually searched and included in the analysis. Two researchers screened the literature according to relevant criteria. The size of the effect was determined using RevMan5.3 software, and the mean difference and 95% confidence intervals (CI) were used to estimate the results using a random effects model.

Results

This meta-analysis included six randomized controlled trials involving 304 patients. The results of the meta-analysis showed that there was no statistical difference in sulcus probing depth status between the VFR group and the HR group, including at 1, 3, and 6 months. Compared with the VFR group, the HR group showed a lower gingival index at 1 month (mean difference = 0.12, 95%CI: 0.06 to 0.19) and 3 months (mean difference = 0.11, 95%CI: 0.06 to 0.17), while there was no statistically significant difference at 6 months (mean difference = 0.10, 95%CI: -0.07 to 0.27). The plaque index of the HR group also showed a good state at 1 month (mean difference = 0.06, 95%CI: 0.01 to 0.12), 3 months (mean difference = 0.12, 95%CI: 0.08 to 0.16), and 6 months (mean difference = 0.19, 95%CI: 0.09 to 0.29). Subgroup analysis of PLI showed that when all teeth were measured, PLI status was lower in the HR group at 6 months (mean difference = 0.32, 95%CI: 0.18 to 0.46). PLI status was also low for the other teeth group (mean difference = 0.15, 95%CI: 0.08 to 0.22).

Conclusion

Our meta-analysis showed that patients using the Hawley retainer had better periodontal health compared with those using vacuum-formed retainers. However, more research is needed to look at the periodontal health of patients using these two retainers.

The Effect of Removable Orthodontic Appliances on Oral Microbiota: A Systematic Review

Background (1): Removable orthodontic appliances may favor plaque accumulation and oral microbe colonization. This might be associated with intraoral adverse effects on enamel or periodontal tissues. The proposed systematic review was carried out to evaluate qualitatively and quantitatively the microbiological changes occurring during orthodontic therapy with removable orthodontic appliances. Methods (2): PubMed, Cochrane Library, Embase, Web of Science, Scopus, Ovid Medline, and Dentistry and Oral Sciences Source were searched. The research included every article published up to January 2020. The Preferred Reporting Items for Reporting Systematic reviews and Meta Analyses (PRISMA) protocol and the “Swedish Council on Technology Assessment in Health Care Criteria for Grading Assessed Studies” (SBU) method were adopted to conduct this systematic review. Results (3): The current study has a moderate evidence, demonstrating that removable appliances do influence the oral microbiota. Significant alterations occur just 15 days after the beginning of therapy, independently from the type of appliance. Furthermore, the levels of oral pathogens decrease significantly or even returned to pre-treatment levels several months later the therapy end. Conclusions (4): This review suggests that orthodontic treatment with removable appliances induces changes to oral microflora, but these alterations might not be permanent.

Parathyroid hormone increases alveolar bone homoeostasis during orthodontic tooth movement in rats with periodontitis via crosstalk between STAT3 and β-catenin

Periodontitis patients are at risk of alveolar bone loss during orthodontic treatment. The aim of this study was to investigate whether intermittent parathyroid hormone (1–34) treatment (iPTH) could reduce alveolar bone loss during orthodontic tooth movement (OTM) in individuals with periodontitis and the underlying mechanism. A rat model of OTM in the context of periodontitis was established and alveolar bone loss was observed. The control, iPTH and iPTH + stattic groups received injections of vehicle, PTH and vehicle, or PTH and the signal transducer and activator of transcription 3 (STAT3) inhibitor stattic, respectively. iPTH prevented alveolar bone loss by enhancing osteogenesis and suppressing bone resorption in the alveolar bone during OTM in rats with periodontitis. This effect of iPTH was along with STAT3 activation and reduced by a local injection of stattic. iPTH promoted osteoblastic differentiation and might further regulate the Wnt/β-catenin pathway in a STAT3-dependent manner. The findings of this study suggest that iPTH might reduce alveolar bone loss during OTM in rats with periodontitis through STAT3/β-catenin crosstalk.

Salivary microbial changes during the first 6 months of orthodontic treatment

Background

Orthodontic treatment is widely used to treat malocclusion. However, the influence of treatment on the oral microbiome remains unclear. In this study, we investigated salivary microbial changes in patients undergoing orthodontic treatment.

Methods

In total, 19 orthodontic patients participated in this study. Saliva samples were collected at the following three timepoints: before (T0) and 3 months (T1) and 6 months (T2) after the placement of orthodontic appliances. High-throughput sequencing was performed based on the 16S rRNA gene V4 region.

Results

The phyla of Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria and Fusobacteria were predominant. Observed Species, Chao1 and ACE, which represent α diversity, were significantly decreased at T1 and subsequently increased at T2. In addition, the β diversity at T1 based on the Bray-Curtis distances differed from T0 and T2. The relative abundances of Prevotella, Porphyromonas and Peptostreptococcus were decreased with treatment, whereas those of Capnocytophaga and Neisseria exhibited the opposite results. In total, 385 of 410 operational taxonomic units were shared at T0, T1 and T2. The co-occurrence networks with hub nodes at T1 were the most complex.

Conclusion

Orthodontic treatment temporarily affected the saliva microbial community. This dynamic alteration in species did not induce deterioration in oral health. Oral hygiene instructions were necessary and should be emphasized during each visit. Further studies with longer observation periods and more participants are required.

Short-term variation in the subgingival microbiota in two groups of patients treated with clear aligners and vestibular fixed appliances: A longitudinal study

OBJECTIVE

To evaluate the subgingival microbiological changes during the first six months of therapy with clear aligners (CAs) and fixed appliances (FAs). The null hypothesis was that there would be no microbiological differences between the two.

SETTING/SAMPLE

Two groups of patients to be treated, respectively, with CAs (14 patients; 9 females and 5 males; mean age 21 years ± 0.25) and FAs (13 patients; 8 females and 5 males; mean 14 years ± 0.75) were consecutively recruited.

MATERIALS AND METHODS

Subgingival microbiological samples were obtained at the right upper central incisor and right first molar at four different time points: before appliance fitting (T0), and at 1 month (T1), 3 months (T3) and 6 months (T6) thereafter. Total bacterial load (TBL) and counts of the bacteria Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Fusobacterium nucleatum, Campylobacter rectus, Treponema denticola and Tannerella forsythia were determined using real-time PCR.

RESULTS

Total bacterial load did not vary in the CA group, while a significant increase was detected after 3 and 6 months of treatment in the FA group. Unlike red complex species, C rectus and F nucleatum were often detected: levels remained stable in the CA group but increased progressively in the FA group.

CONCLUSION

The type of orthodontic appliance influences the subgingival microbiota. TBL increased in the FA group but not in the CA group, although the levels of the individual periodontal pathogenic bacteria species did not significantly increase during the observation period.