The role of probiotics and dietary interventions in the treatment of periodontitis: a pilot randomized controlled clinical trial

Abstract

Background

The aim of this pilot study was to evaluate the effects of probiotic supplementation and diet-supported probiotic use on periodontal clinical parameters in individuals with periodontitis.

Methods

A total of 120 female participants aged between 20 and 60 years, diagnosed with periodontitis and without systemic diseases, were included in the study. Participants were randomly assigned into three groups: control group (conventional treatment), probiotic group (conventional treatment + probiotics), and diet + probiotic group (conventional treatment + probiotics + personalized diet). Clinical evaluations were performed using measurements of probing depth (PD) and clinical attachment loss (CAL), while dietary intake was assessed using three-day food records. Data were analyzed using SPSS 21.0 software, and p < 0.05 was considered statistically significant.

Results

After a six-week follow-up, significant reductions in PD and CAL were observed in the probiotic and especially the diet-supported probiotic groups (p < 0.001). In the diet + probiotic group, PD improved by 41.5% and CAL by 42.7%. Nutritional analysis revealed that protein and fiber intake supported periodontal improvement, whereas sugar and carbohydrate consumption had negative effects (p < 0.05).

Conclusion

Probiotics were found to support periodontal healing, and this effect was significantly enhanced by a personalized anti-inflammatory diet. It is recommended that probiotics and balanced nutrition be integrated into a holistic approach in the treatment of periodontitis.

Trial registration

ClinicalTrials.gov Identifier: NCT06944938, First Submitted: 10/04/2025 (Retrospectively registered) First Posted: 25/04/2025.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-025-06510-4.

Background

Periodontitis is a chronic microbial disease characterized by the inflammatory destruction of the supporting tissues around the teeth [1, 2]. With a high global prevalence, if left untreated, this disease may lead to alveolar bone loss and eventually tooth loss, negatively affecting chewing function, aesthetics, and overall quality of life [3, 4]. While pathogenic microorganisms within dental biofilm play a primary role in the disease’s etiology, the severity of periodontal destruction is also influenced by the degree and imbalance of the host’s immune response [5, 6].

Currently, the foundation of periodontitis treatment consists of mechanical debridement and root surface decontamination. However, these methods may be insufficient in preventing microbial recolonization, particularly in advanced cases, which often require adjunctive therapies. In this context, probiotics have recently garnered attention due to their potential to modulate the periodontal microbiota and regulate the inflammatory response [7–9].

Probiotics are live microorganisms that, when administered in adequate amounts, confer health benefits to the host [10]. Strains such as Lactobacillus and Bifidobacterium have been reported to suppress the colonization of periodontal pathogens, reduce inflammatory markers, and strengthen epithelial barrier functions [11, 12]. Moreover, several randomized controlled trials have indicated that probiotics significantly support clinical attachment gain (CAL) and probing depth (PD) reduction following periodontal therapy [13–16].

This pilot study aimed to evaluate the contribution of probiotics to clinical periodontal healing in patients with periodontitis and to investigate the potential synergistic effects of diet-supported probiotic interventions on periodontal health.

Material and method

Study design

This pilot study was designed as a single-center, randomized controlled, prospective clinical trial conducted between 01.10.2019 and 01.10.2020 at a private dental clinic located in Elazığ, Turkey. The study was approved by the Ethics Committee of Fırat University (Approval No: [15], Date: [17.09.2019]) and carried out in accordance with the principles of the Declaration of Helsinki (2013). All participants were informed about the scope of the study and provided written informed consent. The aim of the pilot study was to compare the effects of probiotic supplementation and diet-supported probiotics, when added to conventional periodontal treatment, on clinical periodontal parameters.

Participant selection

Women aged between 20 and 60 years, with a diagnosis of periodontitis, at least 20 natural teeth, and no systemic diseases were included in the study. Inclusion criteria required probing depths between 3 mm and 7 mm (mild to moderate periodontitis [17]. Exclusion criteria included antibiotic or probiotic use within the last six months, pregnancy or lactation, smoking, and any systemic condition (e.g., diabetes, cardiovascular diseases).

Data collection and sample size

Initially, 140 patients were assessed, and 120 female participants meeting the inclusion criteria were enrolled. In this pilot study, only female participants were included in order to reduce biological variability associated with sex-based differences in immune response, hormonal regulation, and metabolic function. The literature widely documents significant differences between males and females in terms of immune system activity, hormonal balance, microbiota composition, and metabolic responses [18–20]. Therefore, the selection of a single-gender sample is commonly adopted in early-phase clinical trials to minimize variability, enhance internal validity, and facilitate the interpretation of findings. Furthermore, several previous studies evaluating the use of probiotics in the treatment of periodontal diseases have similarly included only female participants, thereby allowing for a more homogeneous analysis of hormonal and metabolic influences [21–24]. Consistent with these approaches, the inclusion of only female participants in the present study contributes to the reliability and interpretability of the observed outcomes. Using a computer-generated randomization table, participants were divided into three groups: control group (n = 40), probiotic group (n = 40), and diet + probiotic group (n = 40). All patients received conventional periodontal treatment. In addition, the probiotic group was administered a daily probiotic supplement for six weeks. The diet + probiotic group received the same probiotic protocol plus a personalized diet rich in fiber and prebiotics, similar to the Mediterranean Diet. Sample size was calculated using G*Power 3.1 software, requiring at least 35 participants per group for 80% power and 5% significance level. To accommodate possible dropouts, 40 participants were included in each group.

Anthropometric measurements

Various anthropometric measurements were conducted to assess body composition. Height and body weight were recorded with participants barefoot and in light clothing using a digital scale and stadiometer. Body mass index (BMI) was calculated by dividing body weight in kilograms by the square of height in meters (kg/m²). Waist circumference, hip circumference, and mid-upper arm circumference (MUAC) were measured using a non-stretchable measuring tape, with participants standing upright and measurements taken at the end of a normal exhalation. All measurements were conducted by the same researcher in the morning following standardized procedures.

Probiotic use and diet intervention

The probiotic supplement used in this study was provided in capsule form and administered orally. Each capsule contained 10⁹ CFU (colony-forming units) of live bacteria, primarily Lactobacillus rhamnosus and Bifidobacterium animalis subsp. lactis. Participants were instructed to take one capsule daily with a glass of water after breakfast for six consecutive weeks. Probiotics were selected for their potential to support periodontal healing by promoting a healthy microbial balance in the gastrointestinal and oral microbiota and modulating inflammatory responses.

For the diet + probiotic group, in addition to the probiotic regimen, a personalized nutrition plan was developed under the supervision of a clinical dietitian. The plan was based on the Mediterranean diet and included foods rich in fiber, antioxidants, prebiotics, and omega-3 fatty acids. Participants were encouraged to consume vegetables, whole grains, legumes, olive oil, walnuts, yogurt, and kefir (natural sources of probiotics and prebiotics). Consumption of sugary beverages, refined carbohydrates, processed foods containing trans fats, and excessive animal fat was restricted. Detailed three-day food records were collected from each participant, and the anti-inflammatory quality of the diet was taken into consideration.

Clinical attachment loss (CAL) measurement

CAL measurements were recorded from six sites per tooth (mesiobuccal, buccal, distobuccal, mesiolingual, lingual, and distolingual) using a calibrated UNC-15 periodontal probe. All measurements were performed by a single dentist blinded to group assignments. Attachment loss was assessed as the distance from the cementoenamel junction to the deepest point of the periodontal pocket. Measurements were taken both at baseline and at the end of the 6th week [25].

Probing depth (PD) measurement

Probing depth (PD) was defined as the distance from the gingival margin to the base of the pocket and measured at six sites per tooth. The same dentist conducted all PD measurements, which were recorded at baseline and at the 6th week post-treatment. Together with CAL, PD was considered a primary clinical outcome measure of this study.

Statistical analysis

Statistical analyses were performed using SPSS version 21.0 (IBM Corp., Armonk, NY, USA). The distribution of continuous variables was assessed using the Shapiro-Wilk test, and the study data were found to be normally distributed. For data with a normal distribution, parametric tests were applied. Chi-square test was used to compare categorical variables among groups. One-way analysis of variance (ANOVA) was used to evaluate differences in continuous variables such as age and anthropometric measurements across groups. Repeated-measures ANOVA was conducted to examine changes in periodontal parameters (PD and CAL) before and after treatment. Furthermore, relationships between dietary intake and clinical outcomes were evaluated using Pearson correlation analysis. A p-value of less than 0.05 was considered statistically significant. In addition to p-values, 95% confidence intervals were also reported to provide a more comprehensive interpretation of the statistical findings.

Results

Table 1 presents the sociodemographic characteristics of the participants. No statistically significant differences were observed among the control, probiotic, and diet + probiotic groups in terms of marital status, education level, employment status, or income level (p > 0.05). These findings indicate that the groups were demographically comparable at baseline, allowing outcome evaluation independent of these variables.

Table 1.

Sociodemographic characteristics of the participants

Sociodemographic Characteristics	Control (n = 40)	Probiotic (n = 40)	Diet + Probiotic (n = 40)	p
Marital Status (Married)	26 (65%)	28 (70%)	27 (67.5%)	0.88
High school or below	19 (47.5%)	18 (45%)	17 (42.5%)	0.92
University or higher	21 (52.5%)	22 (55%)	23 (57.5%)	0.89
Employment Status (Working)	26 (65%)	24 (60%)	25 (62.5%)	0.84
Middle Income Level	29 (72.5%)	30 (75%)	31 (77.5%)	0.76

p: Chi-square test

When age and anthropometric measurements were analyzed (Table 2), no statistically significant differences were observed among the control, probiotic, and diet + probiotic groups regarding age, body mass index (BMI), weight, height, mid-upper arm circumference (MUAC), waist circumference, or hip circumference (p > 0.05). This result indicates that the groups had similar baseline body compositions, ensuring that periodontal improvements could be assessed independently of anthropometric differences.

Table 2.

Age and selected anthropometric measurements of the participants

Age and Anthropometric Measurements	Control (n = 40)	Probiotic (n = 40)	Diet + Probiotic (n = 40)	p
Age (years)	41.8 ± 6.4	42.3 ± 6.1	41.5 ± 6.7	0.81
BMI (kg/m²)	25.9 ± 3.4	25.6 ± 3.2	25.4 ± 3.3	0.76
Weight (kg)	69.0 ± 9.1	68.2 ± 8.5	67.5 ± 8.7	0.68
Height (cm)	165.0 ± 6.0	164.3 ± 5.6	164.8 ± 5.9	0.84
MUAC (cm)	27.8 ± 2.4	27.5 ± 2.3	27.2 ± 2.1	0.72
Waist Circumference (cm)	84.9 ± 6.5	85.1 ± 6.2	84.7 ± 6.0	0.90
Hip Circumference (cm)	97.2 ± 7.4	96.7 ± 7.1	96.3 ± 7.0	0.83

p: ANOVA test

Abbreviations: BMI: Body Mass Index; kg: kilogram; m: meter; cm: centimeter; MUAC: Mid-Upper Arm Circumference

Measurements of PD and CAL at baseline and after six weeks are shown in Table 3. At baseline, the groups had similar periodontal pocket depth (PD) and clinical attachment level (CAL), with no statistically significant differences (p = 0.79 for PD, p = 0.91 for CAL). However, by the end of week 6, significant improvements in PD and CAL were observed, particularly in the probiotic and diet + probiotic groups. The most notable reductions were found in the diet + probiotic group, where PD decreased from 5.3 mm to 3.1 mm and CAL from 5.6 mm to 3.2 mm. Repeated measures analysis confirmed that these differences were statistically significant for both parameters (p < 0.001). These findings suggest that probiotics positively contributed to periodontal healing, and this effect was significantly enhanced when combined with a dietary intervention.

Table 3.

PD and CAL measurements of participants at the beginning and at the end of the 6th week

Time	Measurement	Control (n = 40)	Probiotic (n = 40)	Diet + Probiotic (n = 40)	p
Baseline	PD (mm)	5.3 ± 1.0	5.2 ± 0.9	5.3 ± 1.1	0.79
6 Weeks Later	PD (mm)	4.4 ± 0.9	3.6 ± 0.8	3.1 ± 0.7	< 0.001
Baseline	CAL (mm)	5.5 ± 1.1	5.6 ± 1.0	5.6 ± 1.0	0.91
6 Weeks Later	CAL (mm)	4.8 ± 1.0	3.9 ± 0.8	3.2 ± 0.7	< 0.001

p: Repeated measures ANOVA test

Figure 1 illustrates the improvement rates in PD and CAL among participants. The six-week treatment outcomes of the three groups regarding PD and CAL are presented comparatively. The control group showed a PD improvement rate of 17.0% and a CAL improvement of 12.7%. In the probiotic group, both parameters improved by approximately 30% specifically, PD by 30.8% and CAL by 30.4%. The highest improvements were observed in the diet + probiotic group, with a PD reduction of 41.5% and a CAL reduction of 42.7%. These results demonstrate that probiotic supplementation significantly contributes to periodontal healing, and this effect becomes even more pronounced when supported by an anti-inflammatory diet.

Fig. 1.

Participants’PD and CAL healing rates

Table 4 presents the relationship between participants’ three-day dietary intake and periodontal healing parameters (PD and CAL). According to the analysis, there was a significant negative correlation between protein and fiber intake and PD/CAL values indicating that higher intake of these nutrients was associated with better clinical outcomes (p < 0.05). Conversely, a significant positive correlation was found between carbohydrate and sugar consumption and both PD and CAL, suggesting a negative impact on periodontal healing. No significant relationships were observed with other dietary components (p > 0.05). These findings support the role of dietary content in the periodontal healing process.

Table 4.

Correlation between Three-Day nutrient intake and PD/CAL levels

Energy and Nutrient Intake	Mean Intake (X ± SD)	PD (6th week, mm)	CAL (6th week, mm)	p (PD)	p (CAL)
Energy (kcal)	1850 ± 210	3.1 ± 0.7	3.2 ± 0.7	0.42	0.39
Carbohydrates (g)	220 ± 30	3.4 ± 0.6	3.5 ± 0.6	0.04*	0.03*
Protein (g)	70 ± 10	2.9 ± 0.7	3.0 ± 0.7	0.02*	0.01*
Fat (g)	65 ± 9	3.2 ± 0.8	3.3 ± 0.8	0.51	0.49
Saturated Fat (g)	17 ± 4	3.3 ± 0.7	3.4 ± 0.7	0.54	0.52
PUFA (g)	12 ± 3	3.0 ± 0.7	3.1 ± 0.7	0.16	0.15
MUFA (g)	20 ± 4	3.1 ± 0.7	3.2 ± 0.6	0.33	0.30
Sugar (g)	40 ± 10	3.5 ± 0.6	3.6 ± 0.6	0.03*	0.02*
Fiber (g)	28 ± 6	2.9 ± 0.6	3.0 ± 0.6	0.03*	0.02*

*p: Pearson Correlation Test; p < 0.05 indicates statistical significance

Abbreviations: PUFA: Polyunsaturated Fatty Acids; MUFA: Monounsaturated Fatty Acids

Discussion

Periodontitis is a chronic inflammatory disease affecting the supporting tissues of the teeth, resulting from the interaction between microbial dental plaque and host tissues. If untreated, it can ultimately lead to tooth loss. Therefore, in periodontal therapy, not only mechanical approaches but also adjunctive biological and pharmacological agents have gained importance. Literature indicates that both locally and systemically administered antimicrobial agents are effective in reducing periodontal pathogen load [26, 27]. In addition, emerging adjunctive methods such as photodynamic therapy [27, 28], ozone therapy [29–31] and probiotic applications that have attracted attention especially in recent years [9, 12, 32, 33], have drawn considerable attention for their host-modulating effects. The oral cavity is the initial anatomical site of host-microbe interaction, making the maintenance of microbial balance critical for periodontal health. Some studies have demonstrated that probiotic microorganisms such as Lactobacillus and Bifidobacterium can suppress periodontal pathogens through the production of lactic acid, reactive oxygen species, bacteriocins, and short-chain fatty acids [34–36]. Therefore, the use of probiotics as an adjunct to conventional treatment is increasingly seen as a promising approach to support periodontal tissue healing.

This pilot randomized controlled clinical study investigated the effects of probiotic and diet-supported probiotic use on clinical periodontal parameters in individuals with periodontitis. Our findings revealed that probiotic supplementation made a significant contribution to conventional periodontal therapy, and this effect became even more pronounced when combined with a personalized anti-inflammatory diet.

The beneficial effects of probiotics on periodontal diseases can be explained by modulation of the oral microbiota and balancing of the host immune response. Recent studies have consistently demonstrated the positive effects of probiotics on oral health [37–39]. Nguyen et al. reported that Lactobacillus and Bifidobacterium species inhibit the adhesion and proliferation of pathogenic bacteria while enhancing epithelial barrier function [11]. Similarly, Zhang et al. showed that probiotics reduce inflammatory mediators and accelerate local healing in periodontal disease [12, 40]. These mechanisms align with the significant improvements in PD and CAL observed in our probiotic and diet + probiotic groups.

In our study, the PD improvement rate in the diet + probiotic group was 41.5%, and the CAL improvement rate was 42.7%. These rates are consistent with a randomized controlled study by Morales et al., which reported approximately 30% improvement in a probiotic-only group [16]. However, our findings indicate that the effect was significantly enhanced by dietary support. This is in line with a similar study by Şahin et al., which emphasized that a fiber-rich diet in addition to probiotics led to more rapid improvements in periodontal parameters [14].

Nutrition is a critical factor influencing the structural integrity and function of the periodontium. Inadequate or unbalanced nutrition may weaken immune defenses and impair the maintenance of hard and soft oral tissues. Due to the high cell turnover in periodontal tissues, a continuous supply of essential nutrients is necessary. Studies have shown that macronutrients such as carbohydrates, proteins, and fats, as well as vitamins and minerals, modulate inflammatory processes and shape immune responses. Hence, a balanced diet plays a crucial role in maintaining the balance between oral microbiota and periodontal health. Chronic deficiencies in certain nutrients may lead to pathological changes in periodontal tissues [41–44]. The relationship between nutrition and periodontal disease has received increasing attention in recent years. Given the shared risk factors between periodontitis and systemic conditions like cardiovascular and metabolic diseases, dietary habits with a high inflammatory load may also affect periodontal health. In this context, a study by Sağır et al. reported an inverse association between the Dietary Inflammatory Index (DII) and clinical attachment loss (CAL), with lower CAL scores observed in individuals following anti-inflammatory diets [13]. Similarly, in our study, increased intake of protein and fiber was associated with significantly lower PD and CAL values, while higher consumption of sugar and carbohydrates corresponded with worse periodontal outcomes. These results suggest that diet should not be viewed merely as a supportive element but as an active component of periodontal therapy.

Systematic reviews evaluating the efficacy of probiotics also support these findings. A meta-analysis by Hu et al. confirmed that the addition of probiotics to non-surgical periodontal therapy resulted in significant reductions in PD and CAL [15]. Canut-Delgado et al. emphasized that probiotics not only reduce inflammation but also support tissue regeneration through interaction with immune cells [9].

One of the strengths of this pilot study lies in its randomized controlled design with three groups and the integration of both clinical and dietary data. Detailed analysis of three-day food records provided valuable insight into the direct relationship between diet and periodontal healing. Additionally, the inclusion of only female participants helped minimize hormonal and metabolic variability, which is considered a methodological advantage. The homogeneity in sociodemographic and anthropometric characteristics among the study groups also allowed for unbiased comparisons.

However, certain limitations must be acknowledged. First, the study covered a relatively short duration of six weeks, which limits the interpretation of long-term effects. Second, adherence to the dietary protocol was not strictly monitored, as it was implemented individually at home. The inclusion of only female participants in this study should also be considered a limitation, as it restricts the generalizability of the findings to the broader population, particularly to males. Furthermore, participants were not recruited based on a specific phase of the menstrual cycle, and no biochemical assessment of hormonal status was conducted. This, too, should be regarded as a limitation of the study. As a pilot trial, this study presents preliminary findings and highlights the need for further research with larger and more diverse samples, as well as with objective measures of dietary adherence. In addition, due to the absence of objective assessments of dietary compliance and biological markers (e.g., inflammatory cytokines or microbiota profiles), the improvements observed in this pilot study should not be interpreted as definitive evidence of causality. Nevertheless, the findings offer promising preliminary insights that justify future studies incorporating such biological indicators. Future studies with longer follow-up periods, biomarker measurements, and oral microbiota profiling will allow for a more detailed understanding of the underlying biological mechanisms.

Conclusion

This pilot study demonstrated that probiotic supplementation supports periodontal healing in patients with periodontitis, and this effect is significantly enhanced when combined with a personalized anti-inflammatory diet. The PD and CAL improvement rates observed in the diet + probiotic group were significantly higher compared to those in the groups receiving only conventional treatment. Furthermore, diets rich in protein and dietary fiber, and low in sugar and refined carbohydrates, were found to positively contribute to periodontal treatment outcomes. As a pilot trial, the findings suggest that periodontal therapy should not be limited to mechanical interventions alone, but should also incorporate systemic approaches. Future studies incorporating longer follow-up durations, the inclusion of both female and male participants, and the evaluation of a broader range of biological markers—such as microbiota profiles, antioxidant capacity, and inflammatory cytokines—will help to further clarify the biological foundations of these results and provide stronger evidence regarding the relationship between probiotic use and periodontitis. This study offers promising preliminary findings and may contribute to the development of nutrition-based strategies for the treatment of periodontal diseases in future research.

Electronic supplementary material

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Abbreviations

PD

Probing Depth

CAL

Clinical Attachment Level/Loss

CFU

Colony-Forming Unit

BMI

Body Mass Index

MUAC

Mid-Upper Arm Circumference

DII

Dietary Inflammatory Index

RCT

Randomized Controlled Trial

PUFA

Polyunsaturated Fatty Acids

MUFA

Monounsaturated Fatty Acids

SPSS

Statistical Package for the Social Sciences

ANOVA

Analysis of Variance

UNC-15

University of North Carolina periodontal probe – 15 mm model

aPDT

Antimicrobial Photodynamic Therapy

Author contributions

Conceptualization: F.Ç.Y, N.Ç.G.; methodology: F.Ç.Y., N.Ç.G; data curation: N.Ç.G; data analysis: F.Ç.Y.; writing the first draft: F.Ç.Y.; review and editing: F.Ç.Y., N.Ç.G. All authors have read and agreed to the published version of the manuscript.

Funding

This study was supported by the Dicle University – Scientific Research Projects Coordination Unit (DÜBAP).

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

All the practices in this study were conducted according to the guidelines recommended in the Declaration of Helsinki, and all the procedures involving human subjects were approved by the Ethics Committee of Firat University (Ethics approval number 15/2019). All participants were informed about the scope of the study and provided written informed consent.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.