Oral microbiota transplantation for intra-oral halitosis: a feasibility analysis based on an oral microbiota colonization trial in Wistar rats.

BACKGROUND: Intra-oral halitosis (IOH) is bad breath produced locally by the mouth in addition to systemic diseases and is one of the main causes of interpersonal communication and psychological disorders in modern society. However, current treatment modalities still only alleviate IOH and do not eradicate it. Therefore, based on the differential performance of oral microecology in IOH patients, we propose a microbiota transplantation treatment aimed at restoring oral microecological balance and analyze its feasibility by oral flora colonization test in Wistar rats. OBJECTIVE: Saliva flora samples were collected from IOH patients and healthy subjects to analyze the feasibility of oral microbiota transplantation (OMT) for the treatment of IOH by the Wistar rat oral flora colonization test. METHODS: Seven patients with IOH who visited the First Affiliated Hospital of Xinjiang Medical University from June 2017 to June 2022 with the main complaint of halitosis and three healthy subjects were randomly selected. A Halimeter portable breath detector was used to record breath values and collect saliva flora samples. Sixteen SPF-grade male Wistar rats were housed in the Animal Experiment Center of Xinjiang Medical University and randomly divided into an experimental group (Group E) and a control group (Group C) for the oral flora colonization test. Species composition and associated metabolic analysis of oral flora during the Wistar rat test using 16SrRNA sequencing technology and PICRUSt metabolic analysis. Also, the changes in the breath values of the rats were recorded during the test. RESULTS: The proportion of Porphyromonas, Fusobacterium, Leptotrichia, and Peptostreptococcus was significantly higher in group E compared to group C after colonization of salivary flora of IOH patients (all P < 0.05), and the abundance with Gemella was zero before colonization, while no colonization was seen in group C after colonization compared to baseline. PICRUSt metabolic analysis also showed significantly enhanced IOH-related metabolic pathways after colonization in group E (all P < 0.05), as well as significantly higher breath values compared to baseline and group C (all P < 0.0001). After colonization by salivary flora from healthy subjects, group E rats showed a decrease in the abundance of associated odor-causing bacteria colonization, a reduction in associated metabolism, and a significant decrease in breath values. In contrast, group C also showed differential changes in flora structure and breath values compared to baseline after salivary flora colonization of IOH patients. CONCLUSIONS: OMT for IOH is a promising green treatment option, but the influence of environmental factors and individual differences still cannot be ignored.

Dental restorative materials and halitosis: a preliminaryin-vitrostudy.

Despite the widespread use of dental restorative materials, little information exists in the literature regarding their potential impact on bad breath. This in vitro study aims to fill this gap by investigating the influence of different restorative materials on the release of hydrogen sulfide (H2S). Thirteen diverse dental restorative materials, including composites, flowable composites, glass ionomer restorative materials, high-copper amalgam, and CAD-CAM blocks, were examined. Cellulose Sponge models were used as negative and positive control. All samples were prepared with a diameter of 5 mm and a height of 2 mm. Except for the negative control group, all samples were embedded into Allium cepa L., and the emitted H2S was measured using the Wintact W8802 hydrogen sulfide monitor. Surface roughness's effect on emission was explored by roughening the surfaces of CAD-CAM material samples, and gas emission was measured again. The data were statistically analyzed using the Kruskal-Wallis test and DSCF pairwise comparison tests. Fiber-reinforced flowable composite (EverX Flow), amalgam (Nova 70-caps), and certain composite materials (IPS Empress Direct, Tetric Evoceram, Admira Fusion X-tra) released higher H2S concentrations compared to the negative control. The H2S release period lasted longer in the same materials mentioned above, along with G-aenial Universal Injectable. Indirectly used materials, such as GC Cerasmart, Vita Enamic, and Vita YZ HT, demonstrated significantly lower emissions compared to other direct restoratives. Importantly, the surface roughness of indirect materials did not significantly affect peak H2S concentrations or release times. The study reveals variations in H2S release among restorative materials, suggesting potential advantages of indirect restorative materials in reducing H2S-induced halitosis. This comprehensive understanding of the relationship between restorative materials and halitosis can empower both dental professionals and patients to make well-informed treatment choices. Notably, there is evidence supporting the enhanced performance of indirect restorative materials for individuals affected by halitosis.

[Halitosis. Multidisciplinary approach]. / Khalitoz ­ mezhdistsiplinarnaya problema.

Halitosis is a common complaint among patients. Up to 50% of people worldwide claim to have persistent or intermittent bad breath. Often, bad breath not only disrupts the social life of patients, but is also a symptom of systemic diseases. An important step in the treatment of halitosis is the localization of the source and possible cause of the unpleasant smell. Most often, the problem of halitosis is solved by dentists, because intraoral halitosis accounts for up to 90% of all cases, but doctors of many specialties should deal with the differential diagnosis of its causes. This article considers the main causes of halitosis in patients with diseases of various organ systems.

Diagnosis, management and knowledge of halitosis among Polish and Lebanese dentists: Questionnaire-based survey.

BACKGROUND: Halitosis (fetor ex ore, malodor, bad breath) is defined as an unpleasant odor coming from the oral cavity, regardless of the cause: local or systemic. It affects 22-50% of the population worldwide, leading to a significant decrease in the overall quality of life, and can have oral and extra-oral etiologies. There is an increased interest in the management of halitosis. OBJECTIVES: This study aims to evaluate the patient-dentist communication on halitosis, the dentists' knowledge about the management and etiology of halitosis, and the treatment options used by dentists who practice in Poland and Lebanon. MATERIAL AND METHODS: An online questionnaire was sent to both Lebanese and Polish dentists using Google Forms (Google LLC, Mountain View, USA). In total, 205 dentists completed the questionnaire, of which 100 practiced in Poland (group P) and 105 practiced in Lebanon (group L). A multivariate analysis was conducted to determine differences between both groups and to identify parameters that could influence a dentist's management of halitosis. RESULTS: According to the questionnaire, 86% of group P members and 65.7% of group L members reported communicating with patients about halitosis. Regarding the knowledge of halitosis, 78% of dentists in group P and 85.7% of dentists in group L reported that there is a classification for halitosis. A significant majority of dentists in both groups revealed not having any tool to measure halitosis (67.6% and 68% from group P and group L, respectively). CONCLUSIONS: This study confirms the need for improved communication skills in Polish and Lebanese dentists, as well as for education on the subject among dentists in both countries, and for standardization in diagnosis, treatment modalities and management of halitosis.

Non-Surgical Periodontal Treatment Impact on Subgingival Microbiome and Intra-Oral Halitosis.

The purpose of this study was to characterize and compare subgingival microbiome before and after periodontal treatment to learn if any changes of the subgingival microbiome were reflected in intra-oral halitosis. We tested the hypothesis that intra-oral halitosis (Volatile sulfur compounds levels) correlates with corresponding subgingival bacterial levels before and after periodontal treatment. Twenty patients with generalized periodontitis completed the study. Subgingival plaque samples were collected at baseline and 6-8 weeks after nonsurgical periodontal therapy. Full-mouth periodontal status assessed probing depth (PD), clinical attachment loss (CAL), gingival recession (REC), bleeding on probing (BoP), PISA and PESA. Halitosis assessment was made using a volatile sulfur compounds (VSC) detector device. Periodontal measures were regressed across VSC values using adjusted multivariate linear analysis. The subgingival microbiome was characterized by sequencing on an Illumina platform. From a sample of 20 patients referred to periodontal treatment, 70% were females (n = 14), with a mean age of 56.6 (±10.3) years; full-mouth records of PD, CAL, BOP (%) allowed to classify the stage and grade of periodontitis, with 45% (n = 9) of the sample having Periodontitis Stage IV grade C and 95% (n = 19) had generalized periodontitis. The correlation of bacterial variation with VSCs measured in the periodontal diagnosis and in the reassessment after treatment were evaluated. Fusobacterium nucleatum, Capnocytophaga gingivalis and Campylobacter showaei showed correlation with the reduction of VSC after periodontal treatment (p-value = 0.044; 0.047 and 0.004, respectively). Capnocytophaga sputigena had a significant reverse correlation between VSCs variation from diagnosis (baseline) and after treatment. Microbial diversity was high in the subgingival plaque on periodontitis and intra-oral halitosis participants of the study. Furthermore, there were correlations between subgingival plaque composition and VSC counting after periodontal treatment. The subgingival microbiome can offer important clues in the investigation of the pathogenesis and treatment of halitosis.

Revisiting Standard and Novel Therapeutic Approaches in Halitosis: A Review.

Halitosis, or bad breath, is an oral health problem characterized by an unpleasant malodor emanating from the oral cavity. This condition can have different origins and causes a negative burden in social interactions, communication and quality of life, and can in uncommon cases be indicative of underlying non-oral non-communicable diseases. Most cases of halitosis are due to inadequate oral hygiene, periodontitis and tongue coating, yet the remaining proportion of cases are due to ear-nose-throat-associated (10%) or gastrointestinal/endocrine (5%) disorders. For this reason, the diagnosis, treatment and clinical management of halitosis often require a multidisciplinary team approach. This comprehensive review revisits the etiology of halitosis as well as standard and novel treatment that may contribute to higher clinical success.

Etiology of halitosis in pediatric dentistry.

Halitosis has become a major concern, as it is the third most common reason for dental visits and affects individuals across all ages, genders, and ethnicities. Only a few limited studies have explored the prevalence and etiology of halitosis in the pediatric population. Therefore, the aim of this review was to identify the etiological factors influencing the widespread occurrence of halitosis in pediatric dentistry in order to guide therapy based on the identified causes, thereby improving children's quality of life. The etiology of halitosis is multifactorial; however, in most cases, halitosis is associated with the oral cavity. It can also be related to otorhinolaryngological and respiratory or even gastric diseases. Although halitosis in children is widely associated with poor oral hygiene, we cannot rule out other possible causes, such as otorhinolaryngological and respiratory causes.

A Narrative Review of the Diagnosis, Etiology, and Treatment of Halitosis Over the Past Three Decades.

Although the term "halitosis" was first coined in 1874, people have become increasingly aware of this problem more recently during the COVID-19 pandemic due to extensive wearing of protective masks. In fact, following dental caries and periodontal disease, halitosis is the third most prevalent reason for patients going to the dentist. Due to multifactorial etiology, the diagnosis of halitosis requires a rigorous health/dental/social history, a clinical examination, and measurements. The treatment ranges from the use of dentifrices, mouthwashes, tongue scraping, and masking products, and more recently includes photodynamic therapy, probiotics, and ozone. The purpose of this narrative review was to examine the published literature concerning halitosis over the past 30 years and discuss the diagnosis, etiology, and treatment of the disease.

The efficacy of probiotics in the management of intra-oral halitosis: a systematic review.

OBJECTIVES: To evaluate the efficacy of probiotics in reducing halitosis of dental origin. METHODS: MEDLINE, EMBASE, and CENTRAL were searched up to and including June 2020. Randomised placebo-controlled, double-blinded clinical trials in systemically healthy adult patients who were given any form of probiotics to manage halitosis of dental origin were included. Primary outcome measures were organoleptic scores and volatile sulphur concentration levels. Secondary outcome measures were microbiologic parameters and quality of life (QOL). RESULTS: Of the 301 potentially relevant articles, eight articles were selected for the review. The risk of bias assessment showed that two studies were of low risk of bias, four studies had some concerns, and two studies had a high risk of bias. The beneficial effect of probiotics could neither be confirmed in periodontally treated patients administered with up to 8 weeks of probiotics, nor in periodontitis patients who received both non-surgical periodontal therapy and adjunctive probiotics up to 90 days. Microbiological findings 1 month after probiotics administration and QOL measures showed no significant differences compared to control. Considerable heterogeneity was observed among probiotic administration protocols. CONCLUSIONS: The available evidence suggests no convincing benefit for the use of probiotics in the management of halitosis. Standardised protocols on recruitment of halitosis subjects and organoleptic measurements are required for future studies on probiotics as an intervention. CLINICAL RELEVANCE: The lack of well-conducted studies with a low risk of bias precludes any clinical recommendation. Further research is needed to verify the efficacy of probiotics in the management of intra-oral halitosis.

Effectiveness of oral care interventions on malodour in dogs.

BACKGROUND: Oral malodour is identified by pet owners as an unpleasant inconvenience, but they may not recognise this likely indicates underlying disease. The primary cause of oral malodour relates to the presence of bacteria in the oral cavity often associated with gingivitis and periodontitis. The purpose of this study was to determine the effect of feeding two oral care chews with different textural properties on oral malodour and the proportion of bacterial species involved in the production of volatile sulphur compounds (VSCs). METHODS: Fourteen dogs (9 Petit Basset Griffon Vendéen (PBGV) and 5 Beagle dogs) participated in the randomised cross-over study for a total of 14 weeks. The cohort was divided into four groups with each exposed to a different intervention per week: chew A, chew B, tooth brushing control or a no intervention control. An induced malodour method was used to assess VSCs in breath samples using a portable gas chromatograph (OralChroma™). Microbiological samples (supragingival plaque and tongue coating scrapes) were analysed for VSC-producing bacteria using Oral Hydrogen Sulfide agar with lead acetate. RESULTS: VSCs were detected in the dogs' breath samples and levels of hydrogen sulphide and methyl mercaptan were found to be reduced following an intervention. Chew B significantly reduced the levels of both hydrogen sulphide (p < 0.001) and methyl mercaptan (p < 0.05) compared to no intervention. Reductions in methyl mercaptan were also observed for chew A and tooth brushing but these were not statistically significant. When compared to no intervention, all interventions significantly reduced the total bacterial load and VSC producing bacterial load in plaque (p < 0.001). For tongue samples, only chew B significantly reduced the total bacterial load and VSC-producing bacterial load (p < 0.001) compared to no intervention. CONCLUSIONS: By inducing oral malodour and subsequently applying the one-time interventions, significant reductions in the levels of VSCs were observed. The use of oral care chews texturally designed to deliver a deep, all-round cleaning action can be particularly effective at managing oral malodour in dogs, likely through an enhanced ability to remove bacteria.

Halitosis, what experiences and methods apply Dutch dental hygienists.

OBJECTIVES: The aim of this research is to gain more insight in the methods and experiences of dental hygienists in the Netherlands regarding the treatment of patients with halitosis. MATERIAL AND METHODS: A total of 92 dental hygienists completed the questionnaire (consisting of 19 questions on personal and professional characteristics, clinical observation and treatment of halitosis, the referral of patients with halitosis, the presence and usefulness of a protocol). The questionnaire was distributed using a social media platform for dental professionals in oral health care from all over the Netherlands. RESULTS: 83.4% of 90 dental hygienists had paid attention to the patient's breath but only 37.8% of dental hygienists always informed the patient. Reasons for not informing patients were the fear of the patient's possible reaction or because other oral health problems were more important. Of the included dental hygienists 67.8% had never referred a patient for treatment of halitosis. 86.7% of the dental hygienists stated there was no protocol for diagnosis and treatment of patients with halitosis. However, 90.0% of the dental hygienists acknowledged a protocol would be useful. CONCLUSIONS: The majority of the dental hygienists in the Netherlands had paid attention to the patient's breath, but only a small group of dental hygienists informed their patients about halitosis. In dental practices halitosis is an underestimated problem. During the coronavirus pandemic people are more aware with the smell of their breath. Dental hygienists indicated scaling and root planning and/or providing information and instruction by patients with a bad breath.

Self-perceived halitosis among young adults undergoing orthodontic treatment.

INTRODUCTION: Halitosis is a common oral health problem that significantly impacts the quality of life of the affected individuals. In most cases, poor oral hygiene is responsible for the problem. Orthodontic therapy aims to correct malocclusion using different devices. It has been suggested that orthodontic treatment can promote gingival health by facilitating daily oral hygiene measures. However, the treatment may harm gingival health as these appliances may lead to a more significant accumulation of plaque, increasing the microbial load in the subgingival environment leading to halitosis. OBJECTIVE: The primary goal of this survey is to assess the prevalence of self-perceived halitosis in patients undergoing orthodontic treatment. MATERIALS AND METHODS: An online questionnaire was randomly distributed to patients undergoing orthodontic treatment. A total of 289 subjects completed the questionnaire. It included questions about: demographic data, medical history, social habits, past dental treatment and oral hygiene habits. Descriptive statistics as frequency distributions and percentages were calculated for the study variables. RESULTS: The prevalence of self-perceived halitosis was 41.5%. The majority of the participants started to notice this problem during and after orthodontic treatment (62.5%). A statistically significant correlation was found between the regular dental visits and halitosis in patients with fixed orthodontic appliances (p-value = 0.010). Also, those patients had a substantial increase in tongue coating formation (p- value = 0.010). CONCLUSION: Self-perceived halitosis is a common problem in patients receiving orthodontic treatment.

[Correction of halitosis in chronic inflammatory diseases of the oropharynx in adults]. / Korrektsiya galitoza pri khronicheskikh vospalitel'nykh zabolevaniyakh rotoglotki u vzroslykh.

Approximately 25% of the world population suffer from halitosis, making it a significant medico-social issue. It is one of the clinical signs of chronic inflammatory diseases of the oropharynx and is commonly caused by the persistence some bacteria in the oral cavity and in the oropharynx. These in turn facilitate formation of volatile sulphur compounds. OBJECTIVE: To evaluate the effectiveness and safety of the probiotic strain Streptococcus salivarius K12 in the Bactoblis product in exacerbation of chronic inflammatory diseases of the oropharynx. MATERIAL AND METHODS: 45 patients diagnosed with a diagnosis of exacerbation of chronic pharyngitis were studied, gastroesophageal reflux disease was found in 33 patients. After a microbiological testing, all patients were prescribed probiotic strain Streptococcus salivarius K12 in the amount of 1×109 colony-forming units (CFU) in the form of tablets for resorption as monotherapy for 14 days. The assessment of the therapy was based on physical examination data and on the subjective estimation of the clinical symptoms using a 10-point visual analog scale (VAS) before the start of the treatment and on the 5th and on the 7th day of the therapy. RESULTS: According to the microbiological analysis was revealed the growth of Staphylococcus aureus, Candida albicans, Pseudomonas aeruginosa, Streptococcus agalactiae, Streptococcus viridans which was seen within 103-105 CFU. A significant clinical progress was achieved for all three analyzed signs of diseases (the severity of pain when swallowing, a feeling of perspiration (foreign body) in the pharynx, halitosis), within the statistical significance between the 1st and the 7th day and the 7th and the 14th day of the surveillance. The pain severity was decreased from 5.69±0.39 points to 2.69±0.34 points on the 7th day and to 0.08±0.05 point on the 14th day from the start of the therapy, itchy throat (foreign body sensation) was relived from 6.88±0.23 points to 3.54±0.29 points on the 7th day and to 0.69±0.12 point on the 14th day of the therapy. In addition, there was a decline in the severity of halitosis from 6.16±0.31 points to 2.47±0.44 points on the 7th day and to 0.68±0.29 point on the 14th day of the therapy. CONCLUSION: Topical application of a drug containing a probiotic Streptococcus salivarius K12, in case of chronic inflammatory diseases of the oropharynx of various etiologies, showed satisfactory effectiveness in the regression of the main symptoms of the exacerbation of the inflammatory process, expressed through pain in the throat when swallowing, halitosis and the foreign body sensation in the oropharynx.

Salivary ß-galactosidase, halitosis parameters in periodontal health and disease, and their changes after periodontal treatment.

BACKGROUND: In this study, we aimed to evaluate the salivary ß-galactosidase and Halimeter values (HMV), organoleptic scores (OLS) and Winkel tongue coating index (WTCI) in periodontal health and periodontitis (P), and also their changes after phase I periodontal therapy and tongue cleaning. METHODS: The participants were separated as follows: 25 P with halitosis (Group 1), 25 P without halitosis (Group 2) and 25 healthy controls (Group 3). Periodontal recordings, HMV, OLS and WTCI scores were recorded, and whole saliva ß-galactosidase levels were measured colorimetrically in the samples at baseline and 1 month after the therapy. RESULTS: The baseline values of HMV, OLS, WTCI and salivary ß-galactosidase levels were significantly higher in Group 1 than in Group 2 (P < 0.05). There was a statistically significant decrease in periodontal recordings, HMV, OLS, WTCI and salivary ß-galactosidase levels in all P patients by the therapy (P < 0.05). However, major reductions in halitosis measurements and saliva enzyme levels were observed in Group 1 after the treatment. CONCLUSION: Our results showed that salivary ß-galactosidase was associated with halitosis parameters and phase I periodontal therapy played an important role to reduce this enzyme level and halitosis parameters in P.

Comparative study between photodynamic therapy with urucum + Led and probiotics in halitosis reduction-protocol for a controlled clinical trial.

BACKGROUND: Halitosis is a term that defines any foul odor emanating from the oral cavity. The origin may be local or systemic. The aim of the proposed protocol is to determine whether treatment with antimicrobial photodynamic therapy (aPDT) and treatment with probiotics are effective at eliminating halitosis. MATERIALS AND METHODS: Eighty-eight patients, from 18 to 25 years old with a diagnosis of halitosis (H2S≥112 ppb, determined by gas chromatography) will be randomly allocated to four groups (n = 22) that will receive different treatments: Group 1 -treatment with teeth brushing, dental floss and tongue scraper; Group 2 -brushing, dental floss and aPDT; Group 3 -brushing, dental floss and probiotics; Group 4 -brushing, flossing, aPDT and probiotics. The results of the halimetry will be compared before, immediately after, seven days and thirty days after treatment. The microbiological analysis of the coated tongue will be performed at these same times. The normality of the data will be determined using the Shapiro-Wilk test. Data with normal distribution will be analyzed using analysis of variance (ANOVA). Non-parametric data will be analyzed using the Kruskal-Wallis test. The Wilcoxon test will be used to analyze the results of each treatment at the different evaluation periods. CLINICAL TRAIL REGISTRATION: NCT03996044.

"Say Ahhh": Experience and Views on Halitosis Management in the General Public in Victoria, Australia.

INTRODUCTION: Halitosis is common and can have a significant impact on quality of life. It is attributed to both intraoral and extraoral causes. Although halitosis treatment depends on the aetiology, little is known about consumers' perception of halitosis causes and the types of assistance sought. The Say Ahhh Study aimed to explore the interprofessional care for halitosis and improve understanding by the general public. Phase 1 explored the perceptions of health care providers. This article reports the findings of Phase 2, which explored the general public's knowledge of halitosis, its management, and help-seeking behaviour. METHODS: Patients and clients at 2 medical clinics, 3 dental clinics, and 2 pharmacies in Melbourne and rural Victoria were approached and invited to participate in a short semistructured interview. Qualitative data was thematically analysed. RESULTS: A total of 122 participants (54 males, 66 females, 2 missing) were interviewed. Participants' past experience with halitosis influences their understanding of the cause. Halitosis was attributed mostly to poor oral hygiene and diet and less commonly to systemic disease. Their perception of the condition's severity influenced whether they seek professional help. Their perceived roles of health professionals and ease of access influenced their choice of health professionals to seek help from. CONCLUSION: The Victorian general public is aware of the causes of halitosis and the available treatment options. Choice of treatment and help-seeking behaviour are influenced by experience, perceived severity of the condition, and perceived role of health professionals and their accessibility.

Evaluation of the efficacy of a commercially available regimen vs brushing alone on established plaque and gingivitis on adolescents: Study protocol for a randomized, controlled, blind clinical trial.

BACKGROUND: Dental biofilm accumulation and poor personal oral hygiene are known major risk factors for gingivitis and halitosis. However, it is not clear how studies compare the effectiveness of hygiene regimens, associated with outcomes centered on patients. METHODS: A randomized, blind, controlled clinical trial involving 58 participants aged from 12 to 17 years, who search the Department of Pediatric Dentistry of Universidade Metropolitana de Santos, will be conducted. Immediately, the volunteers will be inserted into Group 1 (commercially available hygiene regimen) or Group 2 (tooth brushing alone). In Group 1, participants will receive Colgate Total 12 toothpastes, Plax mouthwashes and Colgate Ultrasoft toothbrushes, while Group 2 will use Colgate Cavity Protection toothpastes and Colgate Ultrasoft toothbrushes. The interventions will be conducted in the periods of 1, 3, and 6 months after the baseline, when the evaluations will also be performed. Biofilm and halitosis indexes will be evaluated. Data regarding discomfort, satisfaction and the socioeconomic/individual characteristics will also be computed. DISCUSSION: Although toothbrushing has shown positive effects in decreasing biofilm and in gingival health, there is no comparison in the literature of different brushing regimens with halitosis measurement in adolescents. In addition, the effectiveness of these protocols would be confirmed from the acceptability of the volunteers.

Role of Probiotics in Oral Health Maintenance Among Patients Undergoing Fixed Orthodontic Therapy: a Systematic Review of Randomized Controlled Clinical Trials.

The aim was to assess the role of probiotics in oral health maintenance among patients undergoing fixed orthodontic therapy (OT). An unrestricted search of indexed databases was performed until April 2020 using the following Mesh-terms: (1) probiotic and (2) orthodontic. Randomized controlled clinical trials (RCTs) evaluating the influence of probiotic therapy (PT) towards oral health maintenance/improvement in patients undergoing fixed OT were included. Data screening, selection, and extraction were performed; and the risk of bias was assessed using the Cochrane Collaboration's tool. All evaluations were performed by 2 independent researchers; and disagreements were resolved via discussion. Nine RCTs were included. Eight studies reported that PT improves oral health in patients undergoing fixed OT. Seven studies showed that PT reduces the counts of oral pathogenic bacteria in the oral biofilm and/or saliva. One study reported that PT reduces halitosis in patients undergoing fixed OT. One study found that PT reduces the scores of plaque index (PI) and gingival index (GI); and one study reported that PT has no significant influence on PI and GI in patients undergoing fixed OT. One study reported that PT does not prevent the formation of white spot lesions during fixed OT. Three and 6 studies had a moderate and low risk of bias, respectively. A power analysis was performed in 4 studies. In conclusion, probiotics exhibit antimicrobial activity against oral pathogenic bacteria; however, due to the limitations of the studies assessed, further well-designed RCTs are needed.