Efficacy of preprocedural mouth rinses (Chlorhexidine, essential oil, and hydrogen peroxide) in reducing bacterial aerosols during dental scaling

Abstract

Aim

This study aimed to compare the efficacy of mouth rinsing with chlorhexidine, essential oil, and hydrogen peroxide mouthwashes in reducing bacterial infection in aerosols produced during dental scaling.

Materials and methods

Eighty subjects were randomly assigned to four groups. Ten minutes before treatment, participants rinsed for 1 min with 10 mL of either chlorhexidine, essential oil, hydrogen peroxide, or water. Blood agar plates were used to collect aerosols during the scaling procedure, with plates placed at the patient’s chest, dentist’s chest, and assistant’s chest. Plates were exposed for 30 min during and after treatment, incubated at 37 °C for 48 h, and the total number of colony-forming units (CFUs) was counted and analyzed using SPSS-24 software.

Results

The mean age of participants was 35.01 years, with 57.5% female and 42.5% male. A statistically significant difference was observed in the number of bacterial colonies on the patient’s chest plates (882.56 CFUs), dentist’s chest (99.84 CFUs), and assistant’s chest (48.49 CFUs) (p value < 0.001). Chlorhexidine mouthwash significantly reduced bacterial growth compared to the other groups.

Conclusion

Rinsing with chlorhexidine mouthwash before dental treatment effectively reduces bacterial contamination in aerosols, thereby lowering the risk of infection for dental personnel and patients.

Clinical trial number

Not applicable

Introduction

The transmission of infections via aerosols in dental settings poses significant risks to both patients and dental professionals due to the potential spread of infectious agents [1, 2]. Routine dental procedures often generate aerosols containing saliva, blood, and dental tissue, increasing the risk of exposure to pathogens, including coronaviruses [3]. Aerosols, which are suspensions of solid or liquid particles ranging from 0.001 to 100 μm, can penetrate the lungs, with smaller particles (0.5 to 10 μm) being particularly concerning for infection transmission [4]. Dental instruments such as handpieces and ultrasonic scalers contribute to the aerosolization of these contaminants, leading to workplace contamination and heightened risk for dental staff [1, 4].

The concern surrounding aerosol transmission has been amplified in recent years, particularly in light of the COVID-19 pandemic, which has underscored the importance of infection control measures in dental practices. Dental hygienists and practitioners are at an elevated risk for exposure to infectious diseases due to their proximity to patients and the nature of their work, which often involves procedures that generate significant amounts of aerosols [3]. The presence of bacteria and viruses in the oral cavity, including those from the respiratory tract and dental plaque, further complicates the situation, necessitating effective preventive strategies [4].

Research indicates that pre-treatment use of antimicrobial mouthwashes may reduce microbial aerosols [5–8]. Chlorhexidine is the gold standard for antimicrobial rinses due to its broad-spectrum activity and prolonged action, despite known side effects such as temporary loss of taste, tooth discoloration, and mucosal irritation [4]. Its efficacy in reducing bacterial load in the oral cavity has been well-documented, making it a preferred choice among dental professionals. However, while numerous studies have focused on chlorhexidine, there is limited research on the efficacy of herbal mouthwashes, which are gaining popularity among consumers seeking natural alternatives [4].

Herbal products, which are increasingly popular among consumers, may offer a gentler alternative for oral health. Essential oil mouthwashes, containing compounds like thymol, eucalyptol, menthol, and methyl salicylate, have demonstrated effective antimicrobial properties against oral pathogens [4]. These mouthwashes not only help in reducing plaque and gingivitis but also have fewer side effects compared to traditional antiseptics like chlorhexidine [9]. The appeal of essential oil mouthwashes lies in their natural ingredients, which are perceived as safer and less harsh on oral tissues.

In addition to chlorhexidine and essential oils, hydrogen peroxide has also been recognized for its antimicrobial properties. Hydrogen peroxide has been widely used in dentistry since the 1950s, primarily for its oxidizing properties that help in controlling plaque and treating various oral conditions [10]. It is effective against a broad spectrum of microorganisms, including bacteria, yeasts, and viruses, making it a versatile agent in oral hygiene [10]. Studies have shown that hydrogen peroxide can aid in the treatment of gingivitis and other periodontal diseases, further emphasizing its role in maintaining oral health [11, 12].

Despite the established benefits of chlorhexidine, essential oil, and hydrogen peroxide mouthwashes, there is a notable lack of comparative studies assessing their effectiveness in reducing bacterial aerosols during dental procedures. Existing literature predominantly focuses on the individual efficacy of these agents, resulting in a gap in understanding their relative performance in clinical settings. This study aims to address this gap by comparing the efficacy of these mouthwashes in reducing bacterial infection in aerosols produced during dental scaling. Given the critical need for effective infection control measures in dentistry, particularly in light of the challenges posed by aerosol transmission, this research seeks to provide empirical evidence regarding the efficacy of these mouthwashes and aims to inform best practices in dental hygiene and infection control protocols, ultimately enhancing safety for both patients and practitioners.

Materials and methods

Type of study

This study is designed as a prospective interventional study with a before-and-after design.

Study population

The study population comprised patients referred to the special clinic and the Periodontics Department of the Faculty of Dentistry who required scaling and met the inclusion criteria.

Inclusion Criteria:

1. Individuals with at least 20 permanent teeth.

2. Average plaque index between 0.2 and 0.3.

3. Four or more sites with a probing depth of at least 4 mm.

4. Non-smokers.

5. Systemically healthy individuals.

Exclusion Criteria:

1. Use of systemic or topical antibiotics within the past three months.

2. Oral prophylaxis in the past three months.

3. Presence of five or more carious lesions requiring immediate restorative treatment.

4. Pregnant or lactating women.

Sample size and sampling method

The sample size was calculated using a formula with an alpha of 0.05 and a beta of 0.20, assuming a minimum difference of 35% in the distribution of independent variables (10% for p1 and 45% for p2). The calculated sample size was 20 participants per group, leading to a total of 80 participants, with each of the four groups containing 20 individuals. Participants were randomly assigned to the four groups.

Methods and tools for data collection

This prospective interventional study with a before-and-after design was conducted following ethical approval from the Ethics Committee of Kurdistan University of Medical Sciences (approval number: IR.MUK.REC.1400.145). This study does not qualify as a randomized controlled trial (RCT) as it evaluates the efficacy of different mouthwashes (chlorhexidine, essential oil, hydrogen peroxide) and a control group (water) within the same population, rather than comparing interventions across distinct populations [13–16]. Instead, it employs a pre-post intervention design to assess the reduction of bacterial aerosols in each group. All procedures, including participant recruitment, randomization, and data collection, were carried out in strict accordance with the approved protocol. As this study does not meet the criteria for an RCT, registration in clinical trial registries was not required.

Eighty patients with chronic periodontitis and a plaque index between 2 and 3 were selected based on the inclusion and exclusion criteria from the Periodontology Department and the special clinic of Sanandaj Dental School. Random assignment of participants to groups was conducted using an online randomization software (www.randomization.com). The study included three groups receiving different mouthwashes and one control group using water. The mouthwashes and water were placed in indistinguishable dark-colored containers labeled as a, b, c, and d to maintain blinding. Prior to the scaling procedure, a dental student randomly administered one of the mouthwashes to each patient without revealing the type used.

To collect airborne microorganisms, blood agar plates were strategically placed in three locations: the patient’s chest area, the dentist’s chest area, and the assistant’s chest area, with an average distance of 12 inches from the patient’s mouth. Blood agar was selected as the culture medium because it is a general-purpose, nonselective, and enriched medium that promotes the growth of microorganisms, such as those sampled from air. It supports the growth of a wide range of microorganisms, including both Gram-positive and Gram-negative bacteria, which are commonly found in the oral cavity. This choice ensured comprehensive detection and quantification of airborne bacteria, aligning with the study’s objective of assessing overall microbial load [17]. All surfaces were disinfected with 70% isopropyl alcohol before each appointment. Scaling was performed in a standard dental chair with controlled frequency and water pressure, using a piezoelectric device and suction. The same dentist conducted all treatments to ensure consistency.

Patients who met the minimum inclusion criteria were selected, and the nature of the procedure, along with potential risks, was thoroughly explained to them. Written informed consent was obtained from each participant. Systematic sampling was employed to randomly assign patients to one of four groups: Group A (0.2% chlorhexidine), Group B (essential oil), Group C (1.5% hydrogen peroxide), and Group D (water).

The concentrations of the mouthwashes used in this study were selected based on their established efficacy and safety profiles in dental practice. Chlorhexidine gluconate at a concentration of 0.2% was chosen because it is widely recognized as the gold standard for antimicrobial mouth rinses, with proven efficacy in reducing oral bacterial load and preventing plaque formation [18]. Hydrogen peroxide at a concentration of 1.5% was selected due to its antimicrobial properties and its common use in dental settings as a preprocedural rinse [19]. The essential oil mouthwash used in this study was non-alcoholic (Listerine, New Jersey, USA) which contains thymol, eucalyptol, menthol, methyl salicylate. This formulation is commonly used in clinical practice and has been shown to effectively reduce oral bacteria and plaque [9, 20]. The choice of these concentrations and formulations was further supported by their availability, ease of use, and compliance with clinical guidelines for infection control in dental settings.

Ten minutes prior to treatment, participants rinsed their mouths for 1 min with 10 mL of the assigned mouthwash or water. Each treatment session lasted approximately 30 min, during which three marked blood agar plates were placed uncovered at predetermined locations to collect airborne bacterial samples. After the treatment, the agar plates were incubated for 48 h at 37 °C, and the number of colony-forming units (CFUs) was determined in the Department of Microbiology, School of Medicine. Data were subsequently entered into SPSS-24 software for statistical analysis.

Data analysis method

Data analysis was performed using SPSS-24 software. Descriptive statistics were calculated for qualitative variables (frequency and percentage) and quantitative variables (mean and standard deviation) across the four groups. For inferential analysis, ANOVA was employed to compare the mean number of colony-forming units (CFUs) across the four mouthwash groups, as the data met the assumptions of normality (assessed using the Shapiro-Wilk test) and homogeneity of variance (assessed using Levene’s test).

In cases where ANOVA indicated significant differences, post-hoc pairwise comparisons were conducted using the Bonferroni correction to control for Type I error. However, for certain variables that did not meet the assumptions of parametric tests—specifically, CFU counts at specific locations (e.g., the patient’s chest area) where the data were skewed or exhibited unequal variances—nonparametric equivalents, such as the Kruskal-Wallis test, were employed. The Kruskal-Wallis test was chosen because it is suitable for comparing medians across multiple groups when the data do not follow a normal distribution. The use of nonparametric tests was necessary to ensure the validity of the statistical analysis when the assumptions of normality and homogeneity were violated.

All statistical tests were conducted at a significance level of p < 0.05.

Ethical considerations

Ethical approval for this study was obtained from both the Dean and Vice President of Research of the Faculty of Dentistry and the Ethics Committee of Kurdistan University of Medical Sciences (approval number: IR.MUK.REC.1400.145). Written informed consent was secured from all study participants, ensuring that they were fully informed about the study’s purpose, procedures, potential risks, and benefits. Participants were assured of the confidentiality of their information, which was maintained throughout the study by anonymizing data and securely storing records. Participation in the study was entirely voluntary, allowing individuals the option to withdraw at any time without consequence. Additionally, participants were informed that their decision to participate or withdraw would not affect their access to dental care or any other services provided by the clinic. This study was conducted in full accordance with the World Medical Association’s Declaration of Helsinki (1964) and its subsequent amendments.

Results

Part one: descriptive results of the study

The mean age of the patients included in the study was 35.01 years, with a standard deviation of 9.79 years (age range: 16–63 years). The detailed age distribution across the different mouthwash groups is presented in Table 1.

Table 1.

Average age of patients in the study

Variable	Frequency	Minimum	Maximum	Mean	SD
Chlorhexidine	20	18	45	34.15	8.728
Essential Oil	20	16	42	34.90	5.581
Hydrogen Peroxide	20	17	63	36.65	10.545
Water	20	17	57	34.35	12.848
Total	80	16	63	35.01	9.79

Regarding the gender distribution of the study participants, 42.5% were male and 57.5% were female, as shown in Table 2.

Table 2.

Frequency distribution of gender of patients participating in the study

Mouthwash	Gender	Frequency	Percentage
Chlorhexidine	Male	4	20
	Female	16	80
Total		20	100
Essential Oil	Male	6	30
	Female	14	70
Total		20	100
Hydrogen Peroxide	Male	13	65
	Female	7	35
Total		20	100
Water	Male	11	55
	Female	9	45
Total		20	100
Overall Total	Male	34	42.5
	Female	46	57.5

Statistical analysis using the Kruskal-Wallis test revealed a statistically significant difference in the mean number of bacterial colonies across the three sampling locations (p < 0.001). Specifically, the highest number of bacterial colonies was observed in the patient’s chest area, while the lowest was found in the assistant’s chest area (Table 3).

Table 3.

Frequency and mean of colonies formed on plates at three specific sites for each mouthwash type

Mouthwash		Patient’s Chest	Assistant’s Chest	Dentist’s Chest
Chlorhexidine	Frequency	20	20	20
	Mean	623.1	34.85	57.05
	Median	298	24	47.50
	SD	865.818	25.334	43.529
	Max.	49	9	10
	Min.	3800	100	160
Essential oil	Frequency	20	20	20
	Mean	1109.9	31.1	83
	Median	853	24	70
	SD	734.36	15.559	63.986
	Max.	88	11	17
	Min.	2800	70	262
Hydrogen Peroxide	Frequency	20	20	20
	Mean	965.1	66.55	136.05
	Median	796.5	49.5	82.5
	SD	824.126	57.627	122.606
	Max.	78	7	12
	Min.	3360	260	468
Water	Frequency	20	20	20
	Mean	832.15	61.45	123.25
	Median	840	48.5	48
	SD	494.236	52.599	126.074
	Max.	40	15	11
	Min.	1800	250	450

Part two: analytical results of the study

Mean bacterial colonies in patient chest plates across different mouthwash groups

Statistical analysis revealed a significant difference in the mean number of bacterial colonies on patient chest plates among the different mouthwash groups (p value = 0.026). Specifically, the chlorhexidine group exhibited a more substantial reduction in bacterial growth compared to the other groups, which was statistically significant (Table 4).

Table 4.

Mean colonies formed in patient chest plates across different mouthwash groups

Type of Mouthwash	Frequency	SD	Mean	95% Confidence Interval for Mean		Minimum	Maximum	P value
				Upper Limit	Lower Limit
Chlorhexidine	20	865.818	623.1	1028.32	217.88	49	3800	0.026
Essential oil	20	734.36	1109.9	1453.59	766.21	88	2800
Hydrogen Peroxide	20	824.126	965.1	1350.8	579.4	78	3360
Water	20	494.236	832.15	1063.46	600.84	40	1800
Total	80	751.39	882.56	1049.78	715.35	40	3800

Mean bacterial colonies in dentist chest plates across different mouthwash groups

The statistical analysis also indicated a significant difference in the mean number of bacterial colonies on dentist chest plates among the four mouthwash groups (p value = 0.04). The chlorhexidine group demonstrated a statistically significant reduction in bacterial growth compared to the other groups (Table 5).

Table 5.

Mean colonies formed in dentist chest plates across different mouthwash groups

Type of Mouthwash	Frequency	SD	Mean	95% Confidence Interval for Mean		Minimum	Maximum	P value
				Upper Limit	Lower Limit
Chlorhexidine	20	43.529	57.05	77.42	36.68	10	160	0.04
Essential oil	20	63.986	83	112.95	53.05	17	262
Hydrogen Peroxide	20	122.606	136.05	193.43	78.67	12	468
Water	20	126.074	123.25	182.25	64.25	11	450
Total	80	99.421	99.84	121.96	77.71	10	468

Mean bacterial colonies in assistant chest plates across different mouthwash groups

Analysis of the assistant chest plates also revealed a statistically significant difference in the mean number of bacterial colonies among the four mouthwash groups (p value = 0.01). The reduction in bacterial growth was statistically significant for both chlorhexidine and essential oil mouthwashes, with a slight difference between them, compared to hydrogen peroxide and water mouthwashes (Table 6).

Table 6.

Mean colonies formed on assistant chest plates across different mouthwash groups

Type of Mouthwash	Frequency	SD	Mean	95% Confidence Interval for Mean		Minimum	Maximum	P value
				Upper Limit	Lower Limit
Chlorhexidine	20	25.334	34.85	46.71	22.09	9	100	0.01
Essential oil	20	15.559	31.1	38.38	23.82	11	70
Hydrogen Peroxide	20	57.627	66.55	93.52	39.58	7	260
Water	20	52.599	61.45	88.07	36.83	15	250
Total	80	43.88	48.49	58.25	38.72	7	260

Visual representation of results

The results of this study are visually represented in Figs. 1 and 2, and 3, which illustrate the bacterial colony growth on agar plates placed at different locations during the dental scaling procedure.

Fig. 1.

Sample plate placed on the patient’s chest for each mouthwash type: (A) Essential Oil, (B) Water, (C) Chlorhexidine, (D) Hydrogen Peroxide

Fig. 2.

Sample plate placed on the dentist’s chest for each mouthwash type: (A) Essential Oil, (B) Water, (C) Chlorhexidine, (D) Hydrogen Peroxide

Fig. 3.

Sample plate placed on the assistant’s chest for each mouthwash type: (A) Essential Oil, (B) Water, (C) Chlorhexidine, (D) Hydrogen Peroxide

Discussion

Controlling and minimizing microorganisms in aerosols is crucial for the health of dental personnel. Numerous studies have linked these aerosols to the risk of respiratory infections, as well as eye and skin infections, including tuberculosis and hepatitis B [21–25]. These findings indicate that both dental specialists and patients are exposed to significant levels of bacteria [26]. Therefore, the present study aimed to compare the efficacy of mouth rinsing with chlorhexidine, essential oil, and hydrogen peroxide mouthwashes in reducing bacterial contamination in aerosols generated during dental treatment.

The use of ultrasonic scalers has been clearly associated with increased levels of airborne pollutants, with several studies indicating that this procedure is one of the largest contributors to aerosol generation in dentistry [27–29]. A study published by Bennett et al. [28] reported that mechanical scaling procedures were responsible for 47% of peak microbial aerosol concentrations, highlighting the significant risk posed to dental personnel during such procedures. This study measured microbial aerosol concentrations in general dental practices and found that while the average concentration was generally low, peak concentrations were associated with scaling and cavity preparation, suggesting that these procedures can lead to substantial bacterial exposure. One effective method to reduce bacterial contamination during dental procedures is the use of mouthwash prior to treatment [6].

Chlorhexidine, a bisbiguanide molecule, binds strongly to hydroxyapatite, dental plaque, oral mucosa, salivary proteins, and bacteria. This binding results in a prolonged antimicrobial effect, with approximately 30% of the substance released immediately after rinsing and the remainder released gradually over time [15]. Chlorhexidine is recognized as a broad-spectrum disinfectant with potent antimicrobial activity against both gram-negative and gram-positive bacteria, as well as fungi and some viruses. Its ability to inhibit the formation and development of bacterial plaque for several hours was first described in 1970 [10]. Due to its broad-spectrum activity and sustained action lasting 8–12 h, chlorhexidine is considered the gold standard for antimicrobial rinses [4, 18].

The importance of effective infection control measures in dental settings is further underscored by a study conducted by Takenaka et al. [30], which investigated the efficacy of combining extraoral high-volume evacuators (eHVEs) with preprocedural mouth rinsing. Their randomized clinical trial demonstrated that preprocedural rinsing with povidone-iodine and essential oil significantly reduced bacterial contamination in aerosols produced during ultrasonic scaling, with reductions of 31–38% and 22–33%, respectively. The study found that when the eHVE was positioned close to the patient’s mouth, bacterial contamination was negligible, highlighting the effectiveness of this combined approach in minimizing exposure to airborne pathogens. These findings align with our results, which indicate that chlorhexidine mouthwash effectively reduces bacterial growth in aerosols. Taken together, these studies emphasize the critical role of preprocedural mouth rinses and the use of eHVEs in enhancing infection control protocols in dental practices, particularly during procedures that generate significant aerosolization.

In our study, we included 80 eligible subjects with a mean age of 35.01 years. In contrast, the study by Ammu et al. [31] reported a mean age of 43.38 years, which may be attributed to differences in sample size and population characteristics. Gupta et al. [4] found a mean age of 37.98 years, which aligns more closely with our findings. Other studies did not report the mean age of their participants.

Regarding gender distribution, our study comprised 42.5% male and 57.5% female participants. In the study by Asmita et al. [31], the gender distribution was equal, while Gupta et al. [4] reported 33% female and 67% male participants. The higher percentage of female participants in our study may reflect differences in sample size and population demographics. Other studies did not analyze the gender distribution of their subjects.

Our findings revealed a statistically significant difference in the mean bacterial colonies on the chest plates of the patient, dentist, and assistant across the different mouthwash groups. Specifically, the chlorhexidine group exhibited a more substantial reduction in bacterial growth compared to the other groups, and this decrease was statistically significant. These results are consistent with the findings of other studies included in the literature review. In studies by Ammu et al. [31] and Gupta et al. [4], which closely resemble our research, the effects of 0.2% chlorhexidine mouthwash and an herbal mouthwash on bacterial reduction in dental aerosols during scaling were investigated. Ammu et al. [31] found that preprocedural rinsing with 0.2% chlorhexidine significantly reduced aerosolized bacteria, reinforcing the superior effectiveness of chlorhexidine in minimizing bacterial load on blood agar plates compared to herbal mouthwash. This supports our findings that chlorhexidine is an effective preprocedural rinse for reducing bacterial contamination during dental procedures.

Suresh et al. [15] conducted a microbiological study comparing the efficacy of preprocedural rinsing with 0.2% chlorhexidine and an essential oil mouthwash in reducing viable bacteria in dental aerosols during oral prophylaxis. Their results demonstrated that a one-minute preprocedural rinse with chlorhexidine consistently reduced colony-forming units (CFUs) more effectively than rinsing with the essential oil mouthwash. This finding aligns with our results, which indicate that chlorhexidine is superior in minimizing aerosol bacterial load. Similarly, Haffajee et al. [32] investigated the antimicrobial effectiveness of chlorhexidine, an herbal mouthwash, and an essential oil rinse against various oral bacteria. Their study found that chlorhexidine exhibited the lowest minimum inhibitory concentrations (MICs) compared to both the herbal and essential oil rinses, confirming its potent antimicrobial properties. While the herbal mouthwash was more effective than the essential oil rinse in inhibiting certain periodontal pathogens, chlorhexidine remained the most effective agent overall. Together, these studies reinforce the critical role of chlorhexidine as a primary measure for reducing aerosol cross-contamination during dental procedures.

A review by Ather et al. [33] investigated the effects of povidone-iodine, chlorhexidine, hydrogen peroxide, essential oil, and tetravalent ammonium compounds on the SARS-CoV-2 virus. Their results indicated that while these mouthwashes (excluding chlorhexidine) effectively reduced viral load in aerosols during dental treatment, chlorhexidine did not show a significant difference in viral load reduction compared to distilled water.

In the clinical trial conducted by Sreenivasan and Prasad [34], the effects of chlorhexidine mouthwash on clinical parameters of gingivitis, dental plaque, and oral polymorphonuclear leukocytes (PMN) were assessed. Their study revealed significant reductions in PMN levels, with a 35.9% reduction after one week and a 54.9% reduction after two weeks of treatment, alongside improvements in gingival and plaque indices. These findings reinforce the established efficacy of chlorhexidine in reducing oral inflammation and bacterial load. Similarly, a randomized clinical trial by Deshpande et al. [35] compared the anti-plaque and anti-gingivitis effects of chlorhexidine, green tea, and green tea plus ginger mouthwashes in children. The study found that all three mouthwashes significantly reduced gingival and plaque scores over time, with chlorhexidine demonstrating comparable effectiveness. Although the methodology and objectives of these studies differ from ours, they collectively support our findings that chlorhexidine effectively reduces bacterial aerosols during dental scaling procedures. Furthermore, the results suggest that while chlorhexidine remains a potent agent for managing oral health, herbal mouthwashes may serve as effective alternatives or adjuncts in plaque control.

In addition, in the study conducted by Kamdem et al. [36], the in vitro effects of saline mouthwash versus chlorhexidine on oral flora were evaluated. Their research demonstrated that both mouthwashes significantly reduced oral bacteria, with chlorhexidine exhibiting a more prolonged antibacterial effect. Specifically, the study found that while a 2% saline solution had an antibacterial action lasting approximately 3 h, the 0.1% chlorhexidine solution maintained its efficacy for up to 5 h. This reinforces the established efficacy of chlorhexidine in managing oral microbial populations. Although the methodology and objectives of this study differed from ours, it complements our findings by focusing on the effectiveness of chlorhexidine in reducing bacterial aerosols during dental scaling. Together, these studies highlight chlorhexidine’s critical role in infection control within clinical settings, while also suggesting that saline mouthwash may serve as a viable short-term alternative for certain applications.

Another significant finding from our study was the variation in bacterial growth on the plates placed on the patient’s chest, the dentist’s chest, and the assistant’s chest. Our results indicated a statistically significant difference in the number of bacterial colonies across these three locations, with the highest growth observed on the patient’s chest plates and the lowest on the assistant’s chest plates.

Among the studies reviewed, only three specifically examined the bacterial colony counts in aerosols generated during dental procedures, and all reported higher bacterial counts on the plates positioned on the patient’s chest. Although Suresh et al. [15] conducted a microbiological study comparing the efficacy of preprocedural rinsing with 0.2% chlorhexidine gluconate and an essential oil mouthwash. They utilized blood agar plates to collect aerosols during oral prophylaxis, placing the plates at the patient’s and dentist’s chest areas. Their findings indicated that chlorhexidine significantly reduced the colony-forming units (CFUs) compared to the essential oil mouthwash, reinforcing the effectiveness of chlorhexidine in minimizing bacterial contamination during dental procedures.

Similarly, Ammu et al. [31] evaluated the effects of 0.2% chlorhexidine and a commercially available herbal mouthwash on aerosolized bacteria. In their study, 45 patients were randomly divided into three groups, with one group rinsing with distilled water, another with chlorhexidine, and the third with herbal mouthwash. The study found that chlorhexidine mouthwash was significantly more effective in reducing bacterial load on blood agar plates exposed to aerosols produced during scaling, particularly in the patient’s chest area.

Gupta et al. [4] employed a similar methodology, using three blood agar plates placed on the patient’s chest, the dentist’s chest, and the assistant’s chest to assess bacterial contamination. Their results showed that the highest CFUs were found on the patient’s chest plates, while the lowest counts were observed on the assistant’s chest plates. This study also confirmed that preprocedural rinsing with 0.2% chlorhexidine gluconate significantly reduced bacterial aerosols compared to water and herbal mouthwash, highlighting its role as an effective infection control measure in dental settings.

Together, these studies validate our findings that chlorhexidine is effective in reducing bacterial aerosols during dental scaling procedures. They emphasize the importance of using chlorhexidine as a preprocedural rinse to minimize the risk of cross-contamination and protect both dental professionals and patients from potential infections.

Conclusion

The results of this study indicate that the bacterial load in dental aerosols during scaling is highest in the patient’s chest area, with the lowest bacterial growth observed in the assistant’s chest area. Chlorhexidine mouthwash demonstrated a greater reduction in bacterial growth compared to both essential oil mouthwash and hydrogen peroxide, as well as the control group using water. However, no statistically significant differences were found between the essential oil and hydrogen peroxide groups.

These findings suggest that pre-treatment mouth rinses can play a role in minimizing bacterial contamination in aerosols generated during dental procedures. Given the observed efficacy of chlorhexidine in reducing bacterial load, it may be beneficial for patients in dental offices and clinics to use chlorhexidine mouthwash prior to treatment. This practice could potentially help mitigate the spread of contamination and reduce the risk of infection for dental professionals and patients alike.

In light of ongoing concerns regarding aerosol transmission of infectious agents, these results underscore the importance of implementing effective infection control measures in dental practice. Future research should further explore the comparative effectiveness of various mouthwashes and their implications for dental hygiene protocols, contributing to enhanced safety for both patients and dental professionals.

Suggestions

1. Conduct Studies with a Larger Sample Size: Future research should aim to include a larger sample size to enhance the generalizability of the findings and provide more robust statistical analyses.

2. Investigate the Effect of Mouthwashes on Viral Load: Additional studies should explore the impact of chlorhexidine, essential oil, and hydrogen peroxide mouthwashes on the viral load in aerosols generated during dental procedures. This could provide valuable insights into the effectiveness of these mouthwashes in mitigating the risk of viral transmission.

Research limitations

This study has certain limitations that should be acknowledged. First, the analysis focused on aerobic bacteria capable of growing on blood agar plates, as CFUs were the primary outcome measure. This approach allowed for a standardized and reproducible assessment of bacterial load, but it did not account for viruses, anaerobic bacteria, or microorganisms requiring specialized growth conditions. Future studies could expand on these findings by incorporating additional microbial and viral analyses.

Second, the study was conducted at a single center with a sample size of 80 participants. While this sample size was sufficient to detect significant differences among the groups, a larger, multi-center study could further enhance the generalizability of the results to diverse populations and clinical settings.

Third, the study did not control for potential variability in environmental factors, such as room ventilation, humidity, or the precise distance between the patient’s mouth and the agar plates. These factors could be addressed in future research to provide additional context.

Finally, the study focused on the immediate effects of preprocedural mouth rinses on bacterial aerosols during dental scaling. While this provides important evidence for short-term efficacy, future studies could explore the long-term effects of these rinses, including their impact on clinical outcomes such as infection rates among dental personnel.

Abbreviations

CFU

Colony-forming unit

ANOVA

Analysis of variance

SD

Standard deviation

eHVE

Extraoral high-volume evacuator

PMN

Polymorphonuclear leukocytes

MIC

Minimum inhibitory concentration

Author contributions

S.H. conducted the thesis work and contributed significantly to the research design and implementation.M.R. (Corresponding Author) drafted the manuscript, attended to the manuscript submission, and provided oversight throughout the study.H.S. performed the bacterial tests and supervised microbial analysis.A.A. conducted statistical analyses and managed data interpretation.F.R. assisted in drafting the manuscript and contributed to the overall writing process.S.K. (Corresponding Author) was the main investigator, designed the study, provided primary supervision, and contributed to drafting the manuscript.All authors reviewed and approved the final version of the manuscript.

Funding

This study was supported by Kurdistan University of Medical Sciences. No external funding was received.

Data availability

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethical approval

Ethical approval for this study was obtained from the Ethics Committee of Kurdistan University of Medical Sciences (approval number: IR.MUK.REC.1400.145). The study was conducted in full accordance with the World Medical Association’s Declaration of Helsinki (1964) and its subsequent amendments. Written informed consent was secured from all participants prior to their inclusion in the study. Participants were fully informed about the study’s purpose, procedures, potential risks, and benefits, and their participation was entirely voluntary. Confidentiality of participant information was strictly maintained throughout the study.

Consent for publication

Not applicable. No identifying images or personal details are included in this manuscript.

Competing interests

The authors declare no competing interests.