Olive oil-based interventions for gingival inflammation and plaque control- A systematic review of clinical evidence

Abstract

Background

Natural compounds have gained attention for their therapeutic potential in managing oral conditions. Olive oil, known for its anti-inflammatory and antimicrobial properties, may offer clinical benefits in managing gingivitis.

Objectives

This systematic review aimed to evaluate the effectiveness of olive oil in reducing gingival inflammation and plaque accumulation in patients with gingivitis.

Methods

A comprehensive literature search was conducted in PubMed, PROQUEST, and EBSCOhost databases to identify studies published between January 2002 and August 2025 that assessed the impact of olive oil on gingival health. Details collected included the study design, characteristics of participants, nature of the intervention, outcome measures, and principal findings.

Results

Twelve studies that meet the inclusion criteria were analyzed. Evidence suggests that olive oil administered through various forms including, oil pulling, mouthwashes, toothpastes, and ozonated preparations, generally reduced gingival inflammation and plaque accumulation. Ozonated olive oil demonstrated superior efficacy compared to regular olive oil. Few studies found that olive oil interventions are comparable to chlorhexidine in reducing gingival inflammation.

Conclusion

Olive oil appears to be a promising natural adjunct in the management of gingivitis, particularly in ozonated form. While current findings are encouraging, further high-quality studies with standardized methodologies and extended follow-up durations are required to confirm these outcomes and frame clinical guidelines. Dental practitioners may consider incorporating olive oil-based products as an adjunctive option alongside conventional gingivitis treatments.

1. Introduction

Plaque-induced gingivitis is one of the most widespread oral diseases, affecting more than three-quarters of the global population [1]. Gingivitis is primarily initiated and sustained by the buildup of bacterial plaque biofilm on surfaces of the teeth. Progression to periodontitis can occur if left untreated, resulting in irreversible damage to the supporting structures of the teeth, thereby underscoring the critical importance of effective gingivitis management [2].

Gingivitis management primarily relies on two key approaches. The first is a preventive strategy that is focused on controlling plaque accumulation and reducing gingival inflammation [3]. The second involves early intervention of gingivitis through conventional techniques such as regular toothbrushing and interdental cleaning, often complemented by chemical anti-plaque agents like chlorhexidine (CHX) mouthwashes [2,4]. However, despite their proven efficacy, prolonged administration of CHX is associated with adverse consequences, including microbial resistance, disruption of the oral microbiome, tooth discoloration and altered taste perception prompting the exploration of safer, biocompatible natural alternatives with comparable therapeutic efficacy [[5], [6], [7]].

Olive oil - A key ingredient in Mediterranean cuisine is extracted from the fruit of Olea europaea L. Its consumption has been widely recognized for its positive impact on human health, particularly in lowering the likelihood of cardiovascular conditions, various forms of cancer, and metabolic disorders such as type 2 diabetes [8]. In addition to these benefits, olive oil has also been associated with improved cognitive function, anti-inflammatory effects, and enhanced bone health [9]. The diverse health benefits of olive oil are attributed to its rich chemical composition. Its rich composition of monounsaturated fatty acids particularly oleic acid along with bioactive constituents such as polyphenols, underpins its well-documented pharmacological actions, including antioxidant, anti-inflammatory, and antimicrobial effects, all of which contribute significantly to disease prevention and overall health maintenance [8,10].

Numerous studies have highlighted the significant impact of olive oil on multiple facets of oral health. Topical oral applications of olive oil have been found to enhance salivary flow in individuals suffering from drug-induced xerostomia. It is also being investigated for its potential in alleviating pain in patients experiencing burning mouth syndrome [11]. Researchers have explored various modes of application of olive oil, including simple oil pulling to specially formulated toothpastes and mouthwashes, for their ability to reduce gum inflammation and plaque accumulation. Ozonated olive oil formulations have demonstrated enhanced antimicrobial activity compared to conventional olive oil in enhancing oral health [12,13]. Clinical observations show that a 10-min daily gum massage with olive oil, sustained over three weeks, led to a significant reduction in plaque scores [14]. Polyphenolic components of olive oil, particularly oleuropein and hydroxytyrosol, may help control inflammatory responses in gum tissues and interfere with bacterial biofilm development. Additionally, the physical action of oil pulling might also help remove bacteria and toxins from the mouth [3].

Although olive oil has been widely tested for its potential in managing gingival inflammation and plaque accumulation, the clinical data remains fragmented and heterogeneous. Variations in study design, intervention protocols, formulations, and outcome measures limit the ability to draw consistent conclusions regarding its clinical effectiveness or superiority over established plaque control agents such as chlorhexidine. Furthermore, while individual studies have reported promising antimicrobial and anti-inflammatory effects, there is currently a lack of a comprehensive synthesis that critically evaluates these findings across different modes of application.

Therefore, the rationale of this systematic review aims to consolidate and critically appraise existing clinical evidence on olive oil-based interventions in gingivitis management. The novelty of this review lies in its comparative evaluation of different olive oil formulations, alongside conventional treatments, while also integrating mechanistic insights with clinical outcomes to provide a more comprehensive understanding of its therapeutic potential. This approach aims to clarify the clinical relevance of olive oil in contemporary gingivitis management and identify key gaps for future research.

2. Methods

2.1. Protocol outline and research question

This systematic review was conducted in accordance with the standard methods cited in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses [PRISMA] guidelines. The review adopted a structured and evidence-based approach to explore the role of olive oil in promoting oral health, with a particular focus on its impact on reducing gingival inflammation and plaque accumulation. The central objective was to synthesize and critically appraise the existing clinical evidence supporting the use of olive oil-based interventions in managing gingivitis. The PICO framework was employed to develop a focused research question: Population [P] - Individuals diagnosed with gingivitis, Intervention [I] - Olive oil-based therapies [e.g., oil pulling, mouthwash, toothpaste, ozonated olive oil], Comparison [C] - Placebo or conventional treatments [e.g., chlorhexidine], Outcome [O] - Reduction in gingival inflammation and plaque accumulation. Based on this framework, the following research question guiding this review was generated. “What is the clinical efficacy of olive oil-based interventions in reducing gingival inflammation and plaque levels compared to conventional treatments or no treatment in patients with gingivitis?"

2.2. Data sources and search strategy

A comprehensive electronic search was conducted in PubMed, ProQuest, and EBSCOhost to identify studies published between January 2002 and August 2025 that examined the effects of olive oil on gingival health. The search strategy combined controlled vocabulary [e.g., MeSH terms] with free-text keywords, adapted for each database. Search terms and their synonyms included: “olive oil”, “extra virgin olive oil”, “ozonated olive oil”, “oil pulling”, “polyphenols”, in combination with “gingivitis”, “dental plaque”, and “oral hygiene”. The search was restricted to articles published in English. Additionally, manual screening of reference lists from relevant studies was performed to identify further eligible publications.

2.3. Inclusion and exclusion criteria

This review included studies that involved participants clinically diagnosed with plaque-induced gingivitis and where olive oil or its formulations were used as the primary intervention. Only randomized controlled trials [RCTs], clinical trials, and cohort studies were considered. Eligible studies were required to report clinical outcomes related to gingival health, such as the plaque index [PI], the gingival index [GI], or bleeding on probing [BOP].

Literature reviews, editorials and case reports were not considered. Studies with participants who had systemic conditions affecting gum health, studies involving tobacco users and patients with periodontitis, research not using olive oil as the primary intervention and studies that failed to provide quantitative data on gingival or plaque-related outcomes were also excluded. Articles that were not available in full text or were not published in English were excluded from the analysis.

2.4. Data extraction and synthesis

Data from the included studies were extracted by two authors using a structured format covering the study design, sample size, mode of intervention, outcome measures, key findings, magnitude of benefit and study limitations. A third author independently reviewed the extracted data for completeness and accuracy. Discrepancies in data extraction were resolved through mutual discussion. A descriptive synthesis was conducted, categorizing studies by the type of olive oil intervention [oil pulling, mouthwash, toothpaste, and ozonated olive oil], and assessing their reported effects on clinical indices such as gum inflammation, plaque accumulation, and comparisons with conventional treatments. Due to substantial heterogeneity across studies in terms of intervention types, outcome measures, study populations, and follow-up durations, a quantitative meta-analysis was not considered appropriate. Instead, a structured narrative synthesis was undertaken, with studies categorized based on the type of olive oil intervention to facilitate meaningful comparison across similar methodologies and outcomes.

2.5. Quality assessment

The Critical Appraisal Skills Programme [CASP] checklist was applied to evaluate the methodological quality and relevance of the included RCT studies [15]. This tool consists of 11 structured questions that examine aspects such as validity, clarity of reporting, and overall usefulness for clinical decision-making. For each item, a score of 1 was assigned if the criterion was met, 0 if not met, and 0.5 if the information was unclear. The cumulative score was then used to categorize study quality into three levels: high quality [7.35–11], moderate quality [3.68–7.34], and low quality [0–3.67].

2.6. Risk of bias assessment

The methodological rigor of RCTs included in this review was evaluated using the Cochrane Risk of Bias 2 [RoB 2] tool [16]. This framework assesses potential bias across five domains: For each domain, studies were judged as having low risk of bias, some concerns, or high risk of bias, and an overall rating was derived accordingly. To enhance clarity and transparency, the findings of the risk-of-bias assessments were summarized using a traffic-light style visualization and summary plots generated through the robvis application.

3. Results

A total of 430 articles were retrieved from the databases - 165 from PubMed, 215 from ProQuest, and 50 from EBSCOhost. Following the removal of 10 duplicate records, 420 articles remained for initial screening. Based on the evaluation of titles and abstracts, 372 articles were excluded for not fulfilling the eligibility criteria. The remaining 48 articles underwent full-text analysis, after which 36 were excluded for specific reasons outlined in the PRISMA flowchart (Fig. 1). Eventually, 12 studies were selected for the final review.

Fig. 1.

PRISMA flowchart depicted the study selection process.

3.1. Study characteristics

All the selected studies were published between Jan 2002 to Aug 2025 and comprised primarily of RCTs and one non-randomized clinical pilot study [NRCPS] from diverse geographical locations, including India, the United Kingdom, Saudi Arabia, Egypt, Brazil, Italy, and Romania. Sample sizes ranged from 6 to 84 participants per study.

The included studies explored various olive oil–based interventions for oral health. These encompassed the use of olive oil–based mouthwashes or oil pulling with either extra virgin olive oil or “Itri” olive oil. Two studies evaluated olive oil–based toothpaste, while another two investigated gingival massage with olive oil, administered either manually or through a microneedling technique. Control groups varied across studies and included chlorhexidine [CHX] mouthwash or gel, coconut oil, commercial toothpaste, saline or placebo. One trial compared the efficacy of ozonated olive oil [OOO] with that of extra virgin olive oil [EVOO], while another tested EVOO combined with herbal components such as Curcuma zedoaria and Azadirachta indica. The most frequently assessed outcomes were plaque index and gingival index, with some studies also recording bleeding index and oral hygiene index. Of the twelve studies reviewed, three were conducted in pediatric populations, while the remainder involved adult participants. Table 1 presents a comprehensive overview of the characteristics and findings of the 12 studies included in this systematic review.

Table 1.

Characterization of the studies included in the systematic review.

Author & Year	Country	Study Design	Sample size	Intervention/control	Outcome measures	Key Findings	Limitations
Pretty et al., 2003	UK	RCT	20	Olive oil dentrifrice/Fluoride dentrifrice	PI	Significant reduction in plaque in study group compared to control. This new olive oil toothpaste formulation may have the potential to inhibit plaque formation and thus improve gingival health.	Small sample size, No placebo comparison group, results based on single outcome [plaque index]
Singla et al., 2014	India	RCT	32	Gingival massage with Olive oil/Sesame oil/Coconut oil/CHX gel	PI, GI	Significant and comparable reduction in plaque scores, & gingival scores was observed with all the types of oil which was like chlorhexidine gel.	Small sample size, no placebo group without any intervention
Qahtani et al., 2017	Saudi	RCT	60	Oil pulling with Virgin olive oil/CHX mouthwash	PI, modified GI	Virgin olive oil demonstrated notable antimicrobial potential. Oil pulling with Virgin olive oil was found to have comparable effect with chlorhexidine in reducing plaque and gingivitis.	Small sample size, short study duration.
Patel & Deshpande., 2020	India	RCT	34	Oil pulling with olive oil/Coconut oil	PI, GI	Significant reduction in plaque scores, & gingival scores was observed with both the oils. Coconut oil slightly superior in preventing gingivitis compared to olive oil.	Small sample size, no comparison with standard treatments like chlorhexidine.
Akash & Arvina., 2021	India	RCT	66	Olive oil/OOO/CHX mouthwash	GI, OHI	OOO was equally effective in reducing plaque and gingivitis like chlorhexidine mouthwash.	Small sample size, short duration of application,
Ramírez GM et al., 2021	Brazil	RCT	82	Oleanolic acid containing toothpaste/fluoride toothpaste + placebo mouthwash/fluoride toothpaste + CHX mouthwash	GI, Interproximal GI, Gingival severity index, PI, Interproximal PI, gingival bleeding	Oleanolic acid containing toothpaste performed similar antigingivitis effects to CHX. However, it failed to provide antiplaque and antigingivitis effects superior to those of fluoride toothpaste.	Small sample size, short study duration, self-reported bleeding score
Selim & Barakat et al., 2022	Egypt	RCT	75	EVOO 0.9% mouth wash/EVOO 0.5% mouth wash/CHX 0.12% mouthwash	PI, Modified GI	Olive Oil 0.9% group showed a less mean PI and modified GI than Olive Oil 0.5% group than CHX group. Olive Oil 0.9% group showed maximum reduction [30%] in modifie GI score.	Small sample size, no placebo control
Zumbo et al., 2023	Italy	NRCPS	75	EVOO mouthwash/fruity oil mouthwash/control no mouthwash	PI, BI	EVOO group exhibited a 48% reduction in mean PI and 64% reduction in BI which is highest of all the 3 groups	Short duration of application, no comparison with standard treatments like chlorhexidine.
Feier et al., 2023	Romania	RCT	71	OOOMouthwash/EVOO mouthwash	PI, GI, BI	Both groups effective in controlling gingivitis. OOO showed significant reduction in plaque scores, gingival bleeding and GI comapred to EVOO	Short duration; small sample size, no placebo or standard control for comparison
Subasree & Swarna., 2024	India	RCT	24	Microneedling of gingiva with olive oil/subgingival scling	PI, GI	Microneedling of gingiva with olive oil demonstrated a significant enhancement in gingival health and a decrease in both average GI and PI compared to subgingival scaling.	Limited to anterior regionsof gingiva due to dermapen design; small sample size; short follow-up period.
Deshpande et al., 2025	India	RCT	84	EVOO/EVOO with 35% CZ/EVOO with 30% AI/normal saline	Plaque index	EVOO reduced plaque by 91.80%, while EVOO with 35% CZ & EVOO with 30% AI achieved 100% plaque reduction within 72 h	Small sample size, very short study duration, discomfort to patients due to bitter taste of one of the intervention, results cannot generalized due to hospitalized nature of children in the study
Valasingam et al., 2025	India	RCT	20	Oil pulling with EVOO/CHX mouthwash	Plaque index, Gingival index	Both olive oil and CHX showed similar effects in reducing plaque. Olive oil group showed significant reduction of gingivitis scores compared to CHX.	Small sample size

RCT-randomized control trial, NRCPS- Non-randomized clinical pilot study, OOO-ozonated olive oil, CHX- Chlorhexidine, EVOO- extra virgin olive oil, CZ- Curcuma zedoaria, AI-azadirachtaindica, PI- plaque index, GI- Gingival index, BI- Bleeding index.

The CASP critical appraisal indicated that the methodological quality of the included RCTs was generally high. All the studies achieved scores between 8 and 10.5 out of 11, reflecting strong validity, clarity of reporting, and clinical relevance (Table 2). Overall, the findings suggest that the majority of included trials were of robust methodological quality, with only minor limitations identified. Fig. 2 shows the ROB2 evaluation of the included randomized controlled trials. Four of the 11 studies (36%) were judged to have a low risk of bias. Five studies (45%) were classified as having some concerns, while 2 studies [18%] were deemed at high risk of bias. Notably, most trials (81%) employed adequate blinding. The main sources of concern arose from insufficiently reported details on the randomization process, particularly sequence generation and allocation concealment. In addition, several studies lacked pre-registered protocols, analysis plans, or trial registrations. The summary of the distribution of risk-of-bias judgments across individual bias domains in the included randomized studies is shown in Fig. 3. One NRPCS was appraised using the ROBINS-I tool and was found to have a moderate overall risk of bias (Fig. 4). Furthermore, according to the JBI critical appraisal checklist for quasi-experimental studies, this study reflected a moderate risk of bias due to baseline imbalances and limited statistical methods, despite having appropriate controls and consistent outcome measurement.

Table 2.

CASP critical appraisal of RCT studies included in the review.

Author and year	CASP Critical Appraisal scores											Final score
	Q1	Q2	Q3	Q4	Q5	Q6	Q7	Q8	Q9	Q10	Q11
Pretty et al., 2003	1	1	1	0.5	1	1	1	1	1	1	0.5	10
Singla et al., 2014	1	1	0	1	1	1	1	1	1	1	0	9
Qahtani et al., 2017	1	1	1	0.5	1	1	1	1	1	1	0	9.5
Patel & Deshpande., 2020	1	1	1	1	1	1	1	1	1	1	0.5	10.5
Akash & Arvina., 2021	1	1	1	0.5	1	1	1	1	1	1	0.5	10
Gloria et al., 2021	1	1	0	1	1	1	1	1	1	1	0	9
Mahmoud et al., 2022	1	1	1	0.5	1	1	1	1	1	1	0.5	10
Feier et al., 2023	1	1	1	0.5	0.5	1	1	1	1	1	0.5	9.5
Subasree & Swarna., 2024	1	1	1	0	1	1	1	1	1	1	1	10
Deshpande et al., 2025	1	1	0	1	1	1	1	1	1	1	0.5	9.5
Sandeep et al., 2025	1	1	1	0	1	1	1	1	1	1	1	10

Q1: Did the study address a clearly formulated research question., Q2: Was the assignment of participants to interventions randomized., Q3: Were all participants who entered the study accounted for at its conclusion., Q4: Were the participants/investigators/‘blind’ to intervention and people assessing/analysing outcome/blinded., Q5: Were the study groups similar at the start of the randomised controlled trial., Q6: Apart from the experimental intervention, did each study group receive the same level of care., Q7: Were the effects of intervention reported comprehensively., Q8: Was the precision of the estimate of the intervention or treatment effect reported., Q9: Do the benefits of the experimental intervention outweigh the harms and costs., Q10: Can the results be applied to your local population/in your context., Q11: Would the experimental intervention provide greater value to the people in your care than any of the existing interventions.Score1: Yes., Score 0.5:can't tell., Score 0: No.

Fig. 2.

Traffic light plot depicting the ROB2 assessment of the RCTs included in the study.

Fig. 3.

Weighted bar chart showing the percentage distribution of risk-of-bias judgments across the domains.

Fig. 4.

Risk of bias assessment using the ROBINS-I tool for non-randomized control trial.

3.2. Olive oil dentifrice/toothpaste

Two studies evaluated olive oil–based dentifrices for their effectiveness in controlling plaque and gingivitis. Both trials reported significant reductions in plaque scores. Pretty et al. observed a 17–22% inhibition of plaque formation compared with a fluoride-matched control toothpaste, while Gloria et al. found that oleanolic acid–containing toothpaste performed similarly to fluoride toothpaste without showing superior antiplaque or antigingival effects [17,18].

3.3. Gingival massage with olive oil

Two clinical trials have investigated the role of olive oil in gingival massage therapies. In a randomized controlled trial, Singla et al. [2014] demonstrated that daily gingival massage with olive oil for three weeks significantly reduced plaque and gingival index scores, with outcomes comparable to those achieved with chlorhexidine gel, while Subasree et al. [2024] explored a novel approach by combining micro needling with topical olive oil application in patients with mild to moderate gingivitis [14]. Over four weeks, this technique resulted in a pronounced improvement in gingival health, producing statistically significant reductions in both gingival and plaque index scores. Collectively, these findings suggest that direct gingival application of olive oil, whether through massage or micro needling delivery, can effectively mitigate plaque accumulation and gingival inflammation.

3.4. Oil pulling with Olive Oil

Studies evaluating the effects of olive oil pulling on plaque and gingivitis found that participants practicing virgin olive oil pulling showed marked reductions in plaque accumulation and gingival inflammation within two weeks, with a stronger effect on plaque reduction than on gingival scores. Patel and Deshpande. [2020] extended these observations over 30 days, comparing olive oil with coconut oil. Both interventions led to notable decreases in plaque and gingival indices; however, while olive oil produced consistent benefits for gingival health, coconut oil demonstrated comparatively greater overall reductions [19]. More recently, Valasalingam et al. [2025] examined pediatric patients performing olive oil pulling for one month and reported significant improvements in plaque and gingival scores. The olive oil group showed comparable plaque reduction to chlorhexidine, but with a greater decrease in gingival inflammation [20].

3.5. Olive oil-based mouthwashes

Clinical investigations into olive oil-based mouth rinses have shown promising benefits in managing gingivitis. Selim MA et al. [2022] tested the clinical impact of olive oil mouth rinses in children with mixed dentition and compared them with chlorhexidine. Both 0.5% and 0.9% olive oil formulations produced significant reductions in plaque and gingival scores within the first three weeks of use, with the higher concentration showing the greatest effect. Interestingly, the 0.9% olive oil rinse achieved up to a 30% decrease in the gingival index, surpassing the improvement seen with chlorhexidine (16.1%) over the same period. Although differences diminished by the three-month follow-up, the findings suggest that olive oil rinses, particularly at higher concentrations, can serve as an effective short-term adjunct for reducing plaque and gingivitis [21]. In a more recent study, Zumbo et al. [2023] evaluated extra virgin olive oil mouthwash in adults with plaque-induced gingivitis and observed substantial improvements after 30 days. The EVO group demonstrated a 48% decrease in plaque index and a 64% reduction in bleeding index, while a fruity olive oil variant showed more modest but still significant benefits. Both interventions outperformed the control group without any intervention, which showed minimal improvement [22]. Similarly, Akash and Arvina. [2021] compared olive oil, ozonated olive oil, and chlorhexidine mouthwashes in patients with gingivitis and reported that ozonated olive oil achieved reductions in plaque and gingival scores comparable to chlorhexidine, whereas plain olive oil was less effective [23]. Feier et al. [2023] further confirmed these findings in a randomized trial, showing that both ozonated olive oil and extra virgin olive oil mouth rinses significantly reduced plaque, bleeding, and gingival indices after three weeks, with ozonated olive oil providing superior improvements across all parameters [24].

3.6. Enhanced formulations of olive oil

Recent studies have explored enriched f olive oil formulations to enhance clinical efficacy in plaque and gingivitis control. Deshpande et al. [2025] conducted a randomized controlled trial in hospitalized children using topical application of formulations with sterile gauze, rather than conventional rinsing methods. The interventions included extra virgin olive oil (EVOO) alone and EVOO enriched with Curcuma zedoaria (CZ) and Azadirachta indica (AI). The enriched formulations were prepared based on minimum inhibitory concentration testing, with 65% EVOO combined with 35% CZ and 70% EVOO combined with 30% AI (v/v ratios). These preparations were applied twice daily for three days. All groups demonstrated significant plaque reduction within 72 h, with EVOO alone reducing plaque by 91.8%. The CZ-enriched formulation achieved complete elimination of visible plaque (100% reduction), while the AI-enriched formulation also demonstrated near-complete plaque reduction. Both enriched formulations showed greater reductions in plaque and microbial counts compared to EVOO alone and normal saline [25].

4. Discussion

Plaque-induced gingivitis remains one of the most common inflammatory conditions affecting humans [26]. Considering its widespread occurrence and the limitations associated with conventional chemical plaque-control agents, there is an increasing interest in exploring biocompatible and naturally derived alternatives [27]. Among these, olive oil has attracted particular attention due to its diverse biological properties and rich phytochemical composition [22]. Historically revered as “liquid gold” by ancient Greeks and described by Hippocrates as a “great healer,” olive oil continues to be recognized for its therapeutic potential in promoting oral and systemic health [28]^.

Across the included trials, olive oil-based formulations consistently demonstrated effectiveness in reducing dental plaque. Overall, the performance of olive oil preparations on plaque control was comparable to that of (CHX) mouthwashes, suggesting that olive oil can serve as a promising natural adjunct for plaque and gingivitis control [14,18,21,23]. However, the observed clinical and methodological heterogeneity among the included studies further supported the use of a narrative synthesis approach rather than quantitative pooling. Plaque-associated microorganisms in gingivitis include Gram-positive and Gram-negative species such as Streptococcus, Actinomyces, Fusobacterium, Veillonella, and Treponema, with microbial diversity increasing as the disease progresses [29]. Chlorhexidine is regarded as the gold standard for chemical plaque control due to its broad-spectrum activity against these aerobic and anaerobic pathogens. Its cationic structure enables binding to negatively charged bacterial surfaces, causing membrane disruption and leakage of intracellular contents [30,31]. Olive oil has shown comparable antimicrobial potential, with studies reporting significant inhibition of S. mutans, Lactobacillus, P. gingivalis, and F. nucleatum. This effect is attributed to its bioactive components, including oleuropein, hydroxytyrosol, oleocanthal, oleacein, and maslinic acid, which collectively reduce microbial aggregation and plaque formation [14,32].

The common clinical signs and symptoms of plaque-induced gingivitis include inflammatory features such as erythema, edema, bleeding, tenderness, and enlargement confined to the gingiva [33]. At the molecular level, its progression is characterized by elevated expression of pro-inflammatory cytokines such as IL-1 family (IL-1α and β, IL-18, IL-33, IL-36α, β, γ), IL-6, IL-17, IL-23 and TNF-α, within the gingival tissues and in crevicular fluid. These mediators contribute to tissue breakdown, stimulate osteoclast activation, and upregulate matrix metalloproteinase expression [34,35]. The severity and extent of gingival inflammation are commonly assessed using the Gingival Index [GI], introduced by Löe and Silness. [36]. Among all the studies included in this review, olive oil–based interventions consistently demonstrated reductions in GI and bleeding scores, indicating a suppression of inflammatory activity. Its phenolic constituents had been shown to downregulate inflammatory pathways by reducing IL-6, IL-1β, and TNF-α levels, inhibiting NF-κB signaling, and suppressing COX-1 and COX-2 expression [37,38]. Furthermore, clinical studies involving extra virgin olive oil consumption reported reductions in systemic inflammatory markers such as IL-6 and CRP, reinforcing its anti-inflammatory potential in vivo [39]. These findings indicate that olive oil has the potential to modulate the resolution of gingival inflammation.

Extra virgin olive oil was more effective than standard olive oil in plaque suppression, while ozonated olive oil provided the strongest protection against gingivitis [23,24]. Mahmoud et al. demonstrated a dose–response relationship, with higher concentrations of olive oil achieving superior outcomes compared to lower concentrations [21]. Unlike refined oils, EVOO is produced solely through mechanical and physical processes that safeguard its natural composition [40]. This limited processing ensures that valuable bioactive components such as phenolic compounds, pigments, volatile molecules, and antioxidants are preserved. Notably, EVOO contains the highest concentrations of polyphenols, and when unfiltered, it retains additional highly polar phenolics that are usually lost during filtration [41]. These compositional strengths may contribute to EVOO's greater potential in reducing plaque accumulation and gingival inflammation compared to regular olive oil. Ozone, a triatomic form of oxygen, exhibits potent antimicrobial activity primarily through oxidative disruption of microbial cell membranes via ozonolysis, followed by secondary oxidation of intracellular proteins and organelles, ultimately compromising cell viability [42]. In vitro experiments have proven the bactericidal effect of ozonated water on plaque bacteria and inhibitory effect on dental plaque formation. Incorporating ozone within a lipid medium like olive oil greatly improves its stability and facilitates easier application [43]. This combination forms stable ozonides and peroxides that gradually release hydrophilic and lipophilic mediators with targeted antimicrobial and wound-healing effects. From an electrochemical standpoint, the opposing charges between ozone molecules and bacterial cell surfaces facilitate selective attraction and microbial destruction [24]. Ozonated olive oil not only enables localized delivery into gingival and periodontal pockets but also promotes tissue repair. Clinical observations have reported improvements in conditions such as gingivitis, dental caries, and oral mucosal irritation [44]. Moreover, its favorable organoleptic properties, non-toxic nature, and excellent biocompatibility make it a safe and effective adjunct in oral healthcare, showing greater plaque reduction and gingivitis control compared to unmodified olive oil Feier et al. [24]. Collectively, ozonated olive oil integrates the biological benefits of olive oil with the oxidative antimicrobial potency of ozone, presenting a promising alternative for managing plaque-associated gingival inflammation.

Heterogeneity across the included studies is also evident in the type and formulation of olive oil used, including extra virgin, refined, ozonated, and enriched preparations [[23], [24], [25]]. Each formulation differs in its bioactive composition and concentration of phenolic compounds, which may influence the observed clinical outcomes and limit direct comparability between studies. In addition, variations in the mode of intervention represent another important source of heterogeneity. Techniques such as oil pulling, gingival massage or microneedling may independently contribute to reductions in plaque accumulation and gingival inflammation through mechanical disruption of biofilm and stimulation of gingival tissues [14,45]. Therefore, the observed clinical improvements cannot be attributed solely to the biochemical properties of olive oil, as the therapeutic outcomes may result from a combination of mechanical and pharmacological effects. These factors complicate the interpretation of findings and limit the ability to attribute outcomes solely to olive oil-based interventions.

4.1. Clinical implications and practical considerations

Despite the growing body of evidence supporting the potential benefits of olive oil-based interventions, their translation into routine clinical practice remains limited. Several factors may hinder their widespread adoption. First, the lack of standardized formulations and protocols across studies makes it difficult to establish clear clinical guidelines. Second, most available studies are short-term and involve small sample sizes, limiting confidence in long-term effectiveness and safety. Third, variability in application methods creates uncertainty regarding the most effective mode of use. In addition, patient compliance, acceptability due to taste, and lack of commercially standardized products for dental use may further restrict practical implementation. These challenges highlight the gap between experimental findings and real-world application, emphasizing the need for well-designed, large-scale clinical trials and standardized therapeutic protocols before olive oil-based interventions can be routinely recommended in clinical practice.

Another consistent feature noted across all included trials was the absence of any reported adverse effects associated with olive oil-based interventions. Participants tolerated olive oil preparations well, regardless of the type of intervention, and none of the studies documented irritation, staining, or discomfort. This favorable safety profile is likely due to the natural origin and excellent tissue compatibility of olive oil, which supports its recurrent clinical use as a gentle and well-tolerated adjunct in maintaining gingival health.

4.1.1. Study limitations

The available clinical evidence on olive oil in the prevention of plaque accumulation and management of gingivitis provides valuable preliminary insights into its antimicrobial and anti-inflammatory potential. Despite encouraging outcomes, several methodological shortcomings were observed across the included trials. Many studies were limited by small sample sizes, short intervention durations [typically 2- 4 weeks], and the absence of placebo or negative control groups. The diversity in olive oil formulations and concentrations, extending from crude to ozonated or polyherbal forms, limited meaningful comparison across studies. Few investigations reported allocation concealment, blinding methods, or pre-registered protocols, which may introduce bias. Moreover, inconsistent outcome measures, reliance on self-reported bleeding scores, and limited microbiological or biochemical analyses restricted the ability to draw mechanistic inferences. These limitations highlight the need for well-powered, standardized, and longer-term studies to establish the clinical effectiveness and reproducibility of olive oil-based interventions in gingival health.

5. Conclusion

Within the limitations of the available evidence, this systematic review indicates that olive oil-based interventions provide measurable benefits in reducing gingival inflammation and plaque accumulation. Most included studies reported consistent short-term improvements in clinical indices, with ozonated olive oil demonstrating the highest efficacy and outcomes comparable to chlorhexidine. Extra virgin olive oil also showed favorable effects, likely due to its preserved polyphenolic content and antioxidant capacity. Although chlorhexidine remains the benchmark for chemical plaque control, olive oil offers a biocompatible and well-tolerated alternative suitable for patients seeking natural adjuncts or those sensitive to chemical agents. Its antimicrobial and anti-inflammatory properties, largely attributed to phenolic compounds further enhanced by ozone incorporation, support its potential as a safe adjunctive therapy. However, current evidence is insufficient to recommend olive oil as a standalone treatment. Larger, multicenter randomized trials with standardized methodologies and longer follow-up periods are required to confirm its clinical effectiveness. In summary, olive oil represents a promising, accessible adjunct in gingivitis management, warranting further rigorous investigation before clinical integration.

Author contributions

Conceptualization: S N; S AK

Project administration: S N; G AK.

Literature search: K T; A S; SRS.

Data analysis: M K; H B; A S.

Original draft preparation: S N; R A; S B.

Review & editing: S N; S AK; G AK; K T; A S; SRS; M K; H B; A S; R A; S B.

Ethics approval

Ethical approval was not required for this study.

Data availability

The data supporting the findings of this study are available from the corresponding author upon request.

Declaration of generative AI in scientific writing

No AI tools were used to generate the content.

Funding sources

The authors did not receive support from any organization for the submitted work.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.