Periodontal diseases are strongly associated with dysbiosis of the oral microbiome within the biofilm. Key pathogens, including Streptococcus mutans, Aggregatibacter actinomycetemcomitans, and Porphyromonas gingivalis, contribute to caries progression and periodontal inflammation. Given the limitations of antibiotic use and their potential side effects, probiotics represent a promising biological approach to restore microbial balance and support oral health.

In this study, researchers propose that direct application of probiotic spray into the oral cavity is safe and effective in alleviating typical symptoms of periodontal disease, particularly by reducing pathogenic bacterial density.

The objective of this study is to evaluate the safety and efficacy of a oral-spray Bacillus spore probiotics (LiveSpo Smile CARE), containing Bacillus subtilis ANA48 and Bacillus clausii ANA39 at a concentration of ≥ 1 billion CFU/mL x 20 mL formulation, for the prevention and supportive treatment of periodontal disease.

Study Design:

• Sample Size: 90 participants
• Study Location: an elderly care center in Hanoi, Vietnam

Intervention Description: A total of 90 eligible participants will be randomly assigned to two groups (n = 45 per group).

• The Placebo Group will receive 0.9% NaCl physiological saline, spray twice daily (afternoon and evening), with two sprays per application at three sites (both dental arches and the front teeth), totaling six sprays per use, for four consecutive weeks.
• The Smile Care Group will receive an oral-spray probiotics containing ≥ 1 billion CFU/mL × 20 mL of Bacillus subtilis and Bacillus clausii (LiveSpo Smile CARE), administered with the same dosage and frequency as the placebo group.

All participants will receive blinded, coded spray bottles to ensure objectivity. Both groups will be instructed to use the same standardized toothpaste during the study period. Caregivers will monitor the health status of participants and record relevant information in their medical records. During the study, caregivers will be instructed not to provide any additional probiotic oral care products or the solution contains similar components.

Study Duration: 12-18 months.

According to the World Health Organization (WHO), severe oral disease is estimated to affect over 1 billion individuals worldwide. Studies have demonstrated that the prevalence of periodontal disease increases with age. In Vietnam, oral disease is a common oral health problem among the elderly, with a prevalence rate of approximately 91%. This includes 51.6% presenting with simple gingivitis and 39.4% with periodontitis. If left untreated, oral disease may lead to gingival inflammation, swelling, bleeding, and destruction of the supporting structures of the teeth, resulting in pain during mastication. In severe cases, it can cause tooth loss, systemic infections such as sepsis, and increase the long-term risk of systemic diseases including cardiovascular disease and diabetes.

Conventional treatment primarily focuses on the mechanical removal of dental plaque through tooth brushing and flossing. While these methods are effective in reducing gingival inflammation and bacterial load, they often fail to completely eliminate plaque, especially in interdental areas. Probiotics have shown promising potential as adjunctive therapy in the management of periodontal disease by restoring microbial balance, modulating host inflammatory responses, and reducing the levels of pathogenic bacteria.

The objective of this study is to evaluate the prevention and supportive therapeutic efficacy of a oral-spray Bacillus spore probiotics (LiveSpo Smile CARE) in alleviating typical symptoms of periodontal disease. Investigators will assess safety, clinical symptom improvement, and reduction in the oral pathogenic bacterial load in elderly participants after 7, 14, 28, and 42 days of using LiveSpo Smile CARE.

This will be a randomized, blind, placebo-controlled clinical trial. The trial will have 12-18 months of duration. Participants will be required to provide demographic data, oral health history, and information regarding prior antibiotic use. Upon providing written informed consent and meeting eligibility criteria, 90 participants will be enrolled and randomly assigned to two groups (n = 45 per group). The placebo group will receive a 0.9% NaCl physiological saline spray, while the intervention group ("Smile Care") will receive the oral-spray probiotics, LiveSpo Smile CARE.

-Primary outcomes

Changes in clinical symptoms (For example: Debris Index-Simplified [DI-S], Gingival Index [GI], Bleeding on Probing [BOP], Gingival Recession [REC], Probing Depth [PD], Clinical Attachment Level [CAL], Halitosis...) at day 28 vs. day 0.

-Secondary outcomes

Changes in cytokine levels (ELISA) and semi-quantification of bacterial pathogens (real-time PCR) in gingival crevicular fluid samples, collected at day 28 compared with day 0.

- Expected outcomes Change in the oral microbiome composition at day 28 vs. day 0.

Presence of Bacillus subtilis ANA48 and Bacillus clausii ANA39 in gingival fluid will be assessed by real-time PCR at follow-up visits (days 7, 14, 28 and 42) compared with day 0, to confirm product use compliance.

Statistical analysis will be conducted using the chi-square test or Fisher's exact test for categorical variables, and t-test, Mann-Whitney test, or Wilcoxon test for continuous variables, depending on data distribution.

Inclusion Criteria

• Patients aged 35 years and older.
• Patients diagnosed with periodontal disease based on clinical examination, including gingivitis and periodontitis.
• Patients presenting with at least 10 natural teeth in the dental arch.
• Patients with stable general health status and able to comply with study procedures.
• Patients (or their legal guardians) who provide written informed consent and voluntarily agree to participate in the study.

Exclusion Criteria

• Patients with unstable general health, acute systemic or oral diseases, or malignant conditions that may interfere with participation.
• Patients who are currently receiving treatment for periodontal disease at specialized dental facilities.
• Patients currently using any therapeutic or adjunctive products for the management of periodontal disease.

Data or samples share that will be coded, with no PHI include. Approval of the request and execution of all applicable agreements (i.e. a material transfer agreement) are prerequisites to the sharing of data with the requesting party.

Data requests can be submitted starting 9 months after article publication and the data will be made accessible for up to 24 months. Extensions will be considered on a case-by-case basis.

Access to trial IPD can be requested by qualified researchers engaging in independent scientific research and will be provided following review and approval of a study protocol, informed consent form (ICF), and clinical study reports (CSR). For more information or to submit a request, please contact anabio.rd2021@gmail.com

LiveSpo Smile CARE and placebo are indistinguishable regarding taste and smell. The color and turbidity of LiveSpo Smile CARE suspension are unrecognizable to investigators, trainers, caregivers, and paticipants due to opaque plastic container. Only the independent statistician is aware of the group codes.