Oral Health Challenges with Fixed Orthodontics: Can Probiotics Help?

After enduring the discomfort and expense of fixed orthodontia, many individuals are disheartened to find cavities and tooth discoloration upon removal. Fixed dental appliances can complicate proper oral care, which can lead to plaque accumulation and a higher risk of periodontal disease. To lower risks, dental professionals generally advise vigilant oral care with antiseptic oral rinses, fluoride applications, and frequent brushing. More recently, studies revealing changes in the oral microbiome during fixed appliance use have led researchers to explore whether probiotics may be beneficial in maintaining oral health.

This IPA blog will describe the microbial changes during fixed orthodontia use and the research results when probiotics are experimentally administered.

Fixed orthodontic appliances and oral health, in brief

Fixed orthodontic devices including bands, brackets, and arch wires address dental malocclusion but pose challenges to oral hygiene and encourage the buildup of biofilm on both teeth and the appliance surfaces.

Oral biofilms (plaque) consist of microbial communities embedded in an extracellular matrix on mucosal and dental surfaces. While some microbes in the matrix are harmless or even beneficial, pathogenic ones can metabolize dietary sugars into lactic acid, creating an acidic environment that promotes dental caries. Streptococcus mutans (S. mutans) and other cariogenic bacteria thrive in this acidity, leading to tooth demineralization, oral pain, and, if untreated, tooth loss.

Biofilm accumulation also may lead to periodontal disease, a leading cause of tooth loss and a growing public health challenge due to its prevalence and serious complications.

Two types of periodontal disease

Gingivitis:  a mild form of gum disease—inflammation and swelling— caused by the accumulation of dental biofilm. When treated promptly with professional cleaning and antimicrobial rinses, gingivitis is reversible but if left untreated can progress to periodontitis.

Periodontitis: an advanced and irreversible inflammatory disease of the periodontium that damages the tooth-supporting structures, potentially resulting in tooth loss and systemic complications. It is usually caused by bacteria in dental plaque and disproportionate host inflammatory responses. Conventional treatments—enhancing oral hygiene, managing dental biofilm, and removing plaque, along with the use of antimicrobial agents— are not consistently effective. Moreover, antibiotic resistance has become a growing concern.

Orthodontic fixed appliances can increase the incidence of periodontal issues like gingivitis and periodontitis by promoting the accumulation of dental plaque around brackets, wires, and other components. Reviewers point out that “surfaces such as ceramic brackets, molar bands, mini-implant screws, and elastomeric ligatures are particularly prone to plaque accumulation. “ This creates niches that are harder to clean, fostering microbial growth and potential dysbiosis, which can exacerbate inflammation in the gums and surrounding periodontal tissues. Periodontal inflammation left unchecked during orthodontic treatment is a significant factor in accelerating periodontitis and causing tissue destruction.

Proper oral hygiene and education are vital for managing periodontal risks from orthodontic appliances, but innovative therapies are needed to address the complexities of periodontitis.

Microbial changes and fixed orthodontic treatment

The oral cavity harbors the second richest microbial community in the human body, comprising over 700 species of bacteria that colonize both the hard tissues and soft mucosa.

A 2024 review reported that orthodontic therapy with fixed appliances often leads to microbial changes, including increases in S. mutans, Lactobacillus spp., and Candida albicans, which elevate risks of dental caries, periodontal disease, and appliance corrosion. Microbial changes during treatment with fixed appliances start within the first few weeks, with significant changes detected in the first month compared to control groups.

In contrast, clear aligners (removable) allow better oral hygiene and are associated with fewer adverse changes in oral microbiota compared to patients with fixed appliances. Fixed appliance therapy poses a greater risk of periodontal issues compared to clear aligners due to their longer duration and continuous wear.

The negative impact of fixed appliances on oral health was also reported in an earlier review of the literature but with some inconsistent findings.

While some microbial alterations are transient, further research is needed to understand the long-term effects, particularly concerning gram-negative bacteria and other microorganisms such as viruses and protozoa in immunocompromised patients.

Probiotics and oral effects during orthodontic treatment

Mechanisms

Probiotics, particularly lactobacilli and bifidobacteria, may offer an additional treatment benefit for oral health during orthodontic treatment by several mechanisms:

• Host defense modulation: Probiotics may influence innate and adaptive immunity, affect cell proliferation and apoptosis, and reduce mucosal permeability.
• Pathogen inhibition: Probiotics produce antimicrobial substances like lactic acid, hydrogen peroxide, and bacteriocins that directly impact pathogen viability.
• Competitive exclusion: Probiotics may adhere more strongly to oral tissues than pathogens, forming a new biofilm and competing for essential nutrients.

Indeed, many studies have concluded that the use of probiotics can reduce cariogenic S. mutans counts (CFUs) during the time they are used. The effects of probiotics on pathogenic bacteria in biofilms are multiple and vary according to probiotic strain. 

Studies

Several systematic reviews have investigated the role of probiotics in orthodontic practice.

A 2020 review assessed nine randomized controlled studies with patients undergoing fixed orthodontic treatment:

Seven studies showed that probiotic therapy (PT) decreased oral pathogenic bacteria within dental biofilm and/or saliva.

• A single study reported that PT reduced bad breath (halitosis).
• Another study found that PT led to improvements in dental plaque measurements and gingival health indicators.
• One study concluded that PT showed no statistically significant impact on plaque and gingival indices.

A later systematic review and meta-analysis included 15 studies in the qualitative synthesis and 4 in the meta-analysis. All the patients were treated with fixed appliances.

• The meta-analysis results revealed that probiotics increased the likelihood of reducing the abundance of S. mutans to below 10⁵ CFU/ml and reduced the likelihood of increasing the abundance of S. mutans to beyond 10⁶ CFU/ml.
• Yet, four of five studies reported no significant changes in plaque in the probiotic group.
• Two of three studies reported no significant changes in the gingival index in the probiotic group.

The authors of the latter review wrote, “The variations in the probiotic administration vehicle, concentration, strains, and intervention duration could explain these controversial results.” For example, regarding delivery methods, dairy products and mouth rinses emerged as the most effective, demonstrating potential in enhancing enamel remineralization, modulating plaque pH, and reducing S. mutans levels, whereas lozenges showed limited efficacy in promoting oral health. The researchers also said that the optimal strains and concentrations of probiotics for oral health remain unclear, though most studies use doses of 10⁸–10⁹ CFU, with lower concentrations showing limited effects. Lactobacilli and bifidobacteriaspecies are commonly used, and combinations of strains may provide synergistic benefits, but specific outcomes can vary, especially in orthodontic patients with thicker, more pathogenic biofilms.

Takeaway

Fixed orthodontic appliances improve dental alignment but pose challenges to maintaining oral health, increasing the risk of biofilm accumulation, dental caries, and periodontal disease. Research suggests that probiotics, particularly certain lactobacilliand bifidobacteria strains, may help mitigate these risks by modulating the oral microbiome, reducing pathogenic bacteria, and promoting gum health. However, the effectiveness of probiotics varies based on strain, concentration, and delivery method, highlighting the need for further research to optimize their use in orthodontic care.

Image by pololofreack30 from Pixabay

Key references

Albardawel, Lana Hasan et al. “The Effectiveness of Probiotics on Oral Health During Adult Orthodontic Treatment With Fixed Appliances: A Two-Arm Parallel-Group Randomized Controlled Clinical Trial.” Cureus vol. 16,11 e73449. 11 Nov. 2024, doi:10.7759/cureus.73449

Al-Mutairi, Mona A et al. “Microbial Changes in the Periodontal Environment Due to Orthodontic Appliances: A Review.” Cureus vol. 16,7 e64396. 12 Jul. 2024, doi:10.7759/cureus.64396

Amargianitakis, M., M. Antoniadou, C. Rahiotis, and T. Varzakas. “Probiotics, Prebiotics, Synbiotics and Dental Caries: New Perspectives, Suggestions, and Patient Coaching Approach for a Cavity-Free Mouth.” Applied Sciences, vol. 11, no. 12, 2021, p. 5472. doi.org/10.3390/app11125472

Campana, Raffaella et al. “Strain-specific probiotic properties of lactic acid bacteria and their interference with human intestinal pathogens invasion.” Gut pathogens vol. 9 12. 6 Mar. 2017, doi:10.1186/s13099-017-0162-4

Chen, Wener et al. “Effects of probiotics on the oral health of patients undergoing orthodontic treatment: a systematic review and meta-analysis.” European journal of orthodontics vol. 45,5 (2023): 599-611. doi:10.1093/ejo/cjad046

Contaldo, Maria et al. “The Oral Microbiota Changes in Orthodontic Patients and Effects on Oral Health: An Overview.” Journal of clinical medicine vol. 10,4 780. 16 Feb. 2021, doi:10.3390/jcm10040780

Di Spirito, Federica et al. “Periodontal Management in Periodontally Healthy Orthodontic Patients with Fixed Appliances: An Umbrella Review of Self-Care Instructions and Evidence-Based Recommendations.” Dentistry journal vol. 11,2 35. 31 Jan. 2023, doi:10.3390/dj11020035

Do, Thuy et al. “Oral biofilms: molecular analysis, challenges, and future prospects in dental diagnostics.” Clinical, cosmetic and investigational dentistry vol. 5 11-9. 28 Feb. 2013, doi:10.2147/CCIDE.S31005

Gruner, Deborah et al. “Probiotics for managing caries and periodontitis: Systematic review and meta-analysis.” Journal of dentistry vol. 48 (2016): 16-25. doi:10.1016/j.jdent.2016.03.002

Hao, Siyuan et al. “Effectiveness and safety of Bifidobacterium in preventing dental caries: a systematic review and meta-analysis.” Acta odontologica Scandinavica vol. 79,8 (2021): 613-622. doi:10.1080/00016357.2021.1921259

Karkhanechi, Marzieh et al. “Periodontal status of adult patients treated with fixed buccal appliances and removable aligners over one year of active orthodontic therapy.” The Angle orthodontist vol. 83,1 (2013): 146-51. doi:10.2319/031212-217.1

Łasica, Anna et al. “Periodontitis: etiology, conventional treatments, and emerging bacteriophage and predatory bacteria therapies.” Frontiers in microbiology vol. 15 1469414. 26 Sep. 2024, doi:10.3389/fmicb.2024.1469414

Lee, Sung-Hoon, and Young-Jae Kim. “A comparative study of the effect of probiotics on cariogenic biofilm model for preventing dental caries.” Archives of microbiology vol. 196,8 (2014): 601-9. doi:10.1007/s00203-014-0998-7

Lemos, J A et al. “The Biology of Streptococcus mutans.” Microbiology spectrum vol. 7,1 (2019): 10.1128/microbiolspec.gpp3-0051-2018. doi:10.1128/microbiolspec.GPP3-0051-2018

Lucchese, Alessandra et al. “Changes in oral microbiota due to orthodontic appliances: a systematic review.” Journal of oral microbiology vol. 10,1 1476645. 3 Jul. 2018, doi:10.1080/20002297.2018.1476645

Mummolo, Stefano et al. “Salivary levels of Streptococcus mutans and Lactobacilli and other salivary indices in patients wearing clear aligners versus fixed orthodontic appliances: An observational study.” PloS one vol. 15,4 e0228798. 24 Apr. 2020, doi:10.1371/journal.pone.0228798

Pietri, Francesca Katherine et al. “Role of Probiotics in Oral Health Maintenance Among Patients Undergoing Fixed Orthodontic Therapy: a Systematic Review of Randomized Controlled Clinical Trials.” Probiotics and antimicrobial proteins vol. 12,4 (2020): 1349-1359. doi:10.1007/s12602-020-09683-2

Piwat, S et al. “An assessment of adhesion, aggregation and surface charges of Lactobacillus strains derived from the human oral cavity.” Letters in applied microbiology vol. 61,1 (2015): 98-105. doi:10.1111/lam.12434

Seidel, Corinna L et al. “Defining Metaniches in the Oral Cavity According to Their Microbial Composition and Cytokine Profile.” International journal of molecular sciences vol. 21,21 8218. 3 Nov. 2020, doi:10.3390/ijms21218218

Seminario-Amez, M et al. “Probiotics and oral health: A systematic review.” Medicina oral, patologia oral y cirugia bucal vol. 22,3 e282-e288. 1 May. 2017, doi:10.4317/medoral.21494

Sivamaruthi, Bhagavathi Sundaram et al. “A Review of the Role of Probiotic Supplementation in Dental Caries.” Probiotics and antimicrobial proteins vol. 12,4 (2020): 1300-1309. doi:10.1007/s12602-020-09652-9 Twetman, Svante. “Are we ready for caries prevention through bacteriotherapy?.” Brazilian oral research vol. 26 Suppl 1 (2012): 64-70. doi:10.1590/s1806-83242012000700010