Introduction

Individuals who seek orthodontic treatment to correct dental malocclusions often have difficulty in keeping their teeth clean due to malocclusion. 1 The insertion of fixed orthodontic appliances induces an increase in plaque formation associated with a qualitative bacterial shift from aerobic to anaerobic micro flora that endangers the integrity of hard and soft tissues. 2

In clinical studies, an increased incidence of incipient carious lesions and generalized gingival inflammation has been found in patients undergoing fixed orthodontic appliance therapy. The ecological changes in oral microbiota affect the composition, metabolic activity and pathogenicity of the biofilm and can be explained by a higher number of plaque-retentive sites and impaired mechanical plaque removal. Furthermore, it has been observed that the material and surface properties of the bracket can influence bacterial attachment, plaque retaining capacity and microbial diversity. 2 A significant relationship exists between bracket material and biofilm formation on bracket surfaces. 3, 4

The wires can be secured to the bracket by different methods that is, ligation with steel wires, with elastomeric ligatures or self-ligating brackets. Studies suggest that the elastomeric ligatures increase the retention of dental biofilm compared with the two other methods. 1, 2, 3, 4, 5 Recently, lingual treatment technique is being used, to meet the increasing esthetic expectations of orthodontic patients and studies have demonstrated increased biofilm formation with lingual brackets.6

Numerous clinical and laboratory studies have been conducted in patients receiving fixed orthodontic treatment which compared the effectiveness of different types of manual and powered toothbrushes with conventional and advanced designs. However, the results were found to be conflicting. 7 Hence, to overcome the lacunae in literature, the aim of the present study was to evaluate and compare the effects of manual tooth brushing and powered tooth brushing on biofilm formation on metal orthodontic brackets and on gingival and periodontal health of the patient undergoing orthodontic treatment.

Materials and Methods

It was a randomized controlled clinical trial conducted in the department of Orthodontics and Dentofacial Orthopaedics, Chhattisgarh Dental College and Research Institute, Rajnandgaon, Chhattisgarh. A total of 36 healthy patients (no infections or non-infectious diseases, example, HIV, diabetes) in the age range of 15 to 25 years, treated with fixed labial orthodontic appliance with stainless steel brackets, having crowding less than 5 mm and were able to understand and willing to follow the instructions were selected from the Out Patient Department (OPD) of Orthodontics and Dentofacial Orthopaedics and undergoing orthodontic treatment. Subjects with history of professional oral prophylaxis within 6 months before the start of the study, any systemic diseases, immunosuppressant drugs, mentally handicapped subjects, poor manual dexterity, history of periodontal disease or extensive dental restorations or missing central incisors or second premolars were excluded from the study.

A total of 36 patients meeting the inclusion criteria from the out-patient department, were enrolled in the study. Baseline periodontal evaluation that is, API, GI and SBI constituted the readings at T₀ and was performed as follows- API, given by Lange (1977) 8 is used to evaluate the level and rate of plaque formation on tooth surfaces, and to test the efficacy of oral care products for removal and prevention of plaque deposits from these surfaces. API was determined by moving a periodontal probe within the gingival sulcus, buccally in the first and third quadrants, and lingually in the second and fourth quadrants. The presence of plaque after probing was recorded as a positive finding. The API was calculated by dividing the number of positive findings by the number of examined sites, resulting in a percentage index. SBI is an index for assessment of gingival bleeding, developed by Muhlemann and Son.S (1971). 9 This index system is a modification of the papillary-marginal index of Muhlemann & Mazor (1958). 10 The presence of early inflammatory gingival disease can be assessed by gentle probing on the gingival sulcus. SBI was determined by moving a WHO probe within the gingival sulcus towards the papilla from both sides, buccally in the first and third quadrants, and lingually in the second and fourth quadrants. After 10-30 seconds, the results were recorded dichotomously as "+ if bleeding" and/or "- if not bleeding" for every interproximal area. The SBI was calculated by dividing the number of bleeding points by the number of probing sites, resulting in a percentage index. The GI given by Loe and Silness (1967) 11 is used to determine the gingival inflammation. This index scores the marginal and interproximal tissues of the gingiva separately on the basis of score 0 to 3. The GI was evaluated from each of the four gingival areas (buccal, mesial, lingual/palatal, and distal) of the tooth and was given a score from 0 to 3, as shown in the table given below.

Löe and Silness Gingival Index 11

The scores from the four areas of the tooth were added and divided by four to get the GI for the tooth. Finally, by adding the indices for the teeth and dividing them by the total number of teeth examined, the GI for the individual was obtained. The index for each subject was thus an average score for the areas examined. The study participants were subjected to professional oral prophylaxis and periodontal evaluation was repeated 1 week after professional oral prophylaxis as described above. This constituted the readings at T₁. After periodontal evaluation, fixed labial orthodontic treatment was started and bonding of the Koden MBT 0.022" slot brackets using Koden orthodontic adhesive and Bluemax LED light curing unit was performed. The patients were instructed and trained to clean their teeth using toothpaste and Manual Toothbrush for 3 months. After 3 months, periodontal evaluation as described above was performed and readings at T₂ were obtained. A set of two quadrants (first and third quadrant / second and fourth quadrant) was randomly selected, using lottery system, in each patient. A bracket was debonded randomly from central incisor and second premolar from selected quadrant. Thus, two brackets were debonded from each patient. The brackets were carefully removed using J. J Orthodontics Bracket debonding plier without disrupting the biofilm layer and placed in a sterile tray. Immediately after debonding, new Koden MBT 0.022" slot brackets were bonded on the respective tooth. The debonded brackets were stored in separate boxes at room temperature. 6 The brackets were then studied under the SEM for quantitative analysis of biofilm formation, at T₂. Biofilm formation was screened using the Rutherford backscattering detection (RBSD) method on SEM. This technique measured the backscattering of high-energy electrons impinging on a sample. Due to different atomic weights, areas with lighter elements (example, carbon in biofilm) appeared as dark surfaces, and areas with heavier elements (example, iron in stainless steel brackets) appeared as bright surfaces. Biofilm was verified with SEM at high magnification. After conversion to a binary display, the extent of biofilm coverage was calculated based on the different grey values. 3 A binary image was obtained by determining the threshold value in the gray scale. The dark areas of the biofilm, the entire bracket surface area, and their ratio were calculated. Photomicrographs from the vestibular aspect of each bracket were obtained by RBSD method at 20 kV and 50X magnifications. The photomicrographs were analyzed for quantitative biofilm formation. 6 After bonding with new brackets, the patients were randomly divided into two groups (18 participants in each group), using lottery system. Group 1: Patients for Powered toothbrush; Group 2: Patients for Manual toothbrush. Group 1 patients were instructed and trained to clean their teeth using toothpaste and Powered toothbrush while Group 2 patients continued to clean their teeth using toothpaste and Manual toothbrush for next 3 months. After 3 months, periodontal evaluation as described previously was performed again and readings at T₃ were obtained. Then, the brackets were debonded and studied under SEM, at T₃ in a similar way as described above.

Statistical Analysis

Data obtained was compiled on a MS Office Excel Sheet (v 2019, Microsoft Redmond Campus, Redmond, Washington, United States). Data was subjected to statistical analysis using the Statistical package for social sciences (SPSS v 26.0, IBM). In this study, biofilm formation with manual and powered toothbrush as well as various periodontal evaluation such as approximal plaque index, sulcular bleeding index and gingival index were tested and compared. All the values for each index were recorded, tabulated, and statistically analyzed to calculate the mean and standard deviation for each group. All data was entered into a computer by a coding system and was checked to avoid any entry errors or repetitions. Descriptive statistics like frequencies and percentage for categorical data, Mean & SD for numerical data have been depicted. Friedman, Wilcoxon signed rank, Mann-Whitney U and Shapiro-Wilk test were the various tests used for testing of data.

Results

All 36 patients completed the study with no adverse effects reported by any of the subjects or noted by the examiner. No difference was found in the brushing skill of the patients with manual toothbrushes in reducing plaque on metal orthodontic brackets. No significant difference was seen in API (P = .249), SBI (P = .643) and GI (P = .104) values between T₂ & T₁ time intervals on comparing both the groups. The inter-group comparison of differences in values for API, SBI, GI score between T₂ & T₁ time intervals is shown in Table 1.

Figure 1

Diagnostic instruments

Figure 2

Orthodontic bonding material

Figure 3

Colgate manual (Left) and powered toothbrush (Right)

Figure 4

Scanning electron microscope

Figure 5

Setup of Scanning electron microscopy

Figure 6

Loading of samples for SEM testing

Figure 7

SEM images of upper central incisor bracket

Figure 8

SEM images of upper second premolar bracket

Figure 9

SEM images of lower central incisor bracket

Figure 10

SEM images of lower second premolar bracket

Figure 11

Binary image of a central incisor bracket

Figure 12

Periodontal evaluation at T₀

Figure 13

Periodontal evaluation at T₁

Figure 14

Periodontal evaluation at T₂

Figure 15

Debonding of the bracket for SEM evaluation

Figure 16

Periodontal evaluation at T₃

All the patients cleaned their teeth with equal efficiency in both the groups. The inter group comparison of values for API, SBI, GI at T2 time interval as shown in Table 2, showed statistically significant difference between the groups for GI score (P = .016). No statistically significant difference was observed for API (P = .248) and SBI (P = .086) scores.

Powered toothbrushing was found to be more effective in reducing API and SBI scores, as statistically high significant difference was seen in API score (P = .004) and SBI score (P < .001) between T₃ & T₂ time intervals on comparing both the groups. Both the manual and powered toothbrushing had equal effect on GI scores, no significant difference was seen in GI score (P = .540) between T₃ & T₂ time intervals on comparing both the groups (Table 3).

At T₃ time interval, powered toothbrushes were found to be more effective in reducing gingival inflammation, statistically high significant difference for the values between the groups for all the three parameters (API, SBI and GI). API, SBI and GI showed higher values for group II patients (Manual toothbrushing) (API= 70.23±15.45, SBI= 73.61±15.97, GI= 0.72±0.12) (Table 4).

On inter group comparison of amount of biofilm formation between T2 & T3 time intervals in anterior and posterior region, higher amount of biofilm formation in both the anterior and posterior regions in group II patients (Anterior region= 12.05±6.90, P = .001, posterior region= 10.32±9.75, P = .001) (Table 5).

Discussion

Fixed orthodontic treatment allows three-dimensional correction of malocclusions.12 Bonding of orthodontic brackets presents a major advancement in orthodontics after years of using multi banded fixed appliances.13 Epidemiological and experimental studies have demonstrated that gingival inflammation, as well as dental caries, is dependent upon the presence of bacterial plaque on the teeth.14

The most interesting field of research presents the determination of periodontopathogenic bacterial changes in subgingival dental plaque in patients undergoing fixed orthodontic treatment. 15, 16 This includes evaluation of quantitative and qualitative shifts of dangerous, black-pigmented anaerobes such as Prevotella inter media and Actinobacillus actinomycetemcomitans, the microbes solely responsible in the initiation and progression of periodontitis. 17, 18, 19

The placement of fixed appliances not only encourages biofilm formation but also raises the level of acidogenic bacteria inside the biofilm. 20 If patients do not maintain good oral hygiene during orthodontic treatment, the dental biofilm will produce acids that lead to enamel demineralization and white spot lesions around the orthodontic appliance. Development of the biofilm is related to the presence of gingivitis, and greater the plaque accumulation, the higher the gingival bleeding index.21, 22 Because of the unpredictable nature of periodontal disease progression, orthodontic patients with gingivitis must be considered to be at risk of periodontal damage.

Toothbrushing is an important procedure to maintain oral hygiene and therefore, gingival, and periodontal health, during orthodontic treatment. There are many evidences that toothbrushing reduces gingivitis. It may prevent periodontitis and certainly prevents tooth decay if carried out in conjunction with fluoride toothpaste. These benefits occur whether the brush is manual or powered and the results of review conducted by Lang et al do not indicate that toothbrushing is only worthwhile with a powered toothbrush.13 This randomized controlled clinical trial provides important information on the efficacy of powered toothbrush, for the oral health of patients undergoing fixed orthodontic therapy, using scanning electron microscope.

The novelty of the present study was that in this study, along with periodontal evaluation i.e., API, SBI and GI, quantitative evaluation of amount of biofilm formation on metal orthodontic brackets under scanning electron microscope using Rutherford back scattering detection (RBSD) was done. The RBSD photomicrographs allowed the detection of biofilm-coated surfaces. Biofilm coverage was validated by using SEM with high magnification. In the RBSD technique, primary electrons leave the sample as a consequence of an elastic scattering process depending on atomic weight (Rutherford backscattering). In these element-contrast photomicrographs, surfaces covered with elements of low atomic weight (such as oral biofilms) give darker images than surfaces with a higher atomic weight (such as stainless steel) and software-assisted analysis of biofilm coverage can be performed on the basis of the resulting differences in grey values. Plaque- and non-plaque covered surfaces were differentiated on the basis of the grey values after conversion to a binary display. The extent of coverage with biofilm was calculated using surface analysis software (Image J software). A lesser ratio indicated less biofilm accumulation. 3, 4, 5, 6

In this study periodontal indices, including API, SBI and GI, were recorded at four sessions for each patient i.e., before oral prophylaxis (T₀), after oral prophylaxis (T₁), after 3 months of bonding (T₂) and after 6 months of bonding (T₃). 3 months after bonding, T₂ readings were recorded and then the participants were divided into two groups i.e., Group I- Powered toothbrushing & Group II- Manual toothbrushing, before which all patients were performing manual toothbrushing. The study design offered an advantage that effects of the two types of toothbrushes can be measured in the same participant as half of the study participants used manual toothbrush for first three months after bonding (T₁ to T₂) and then were asked to use powered toothbrush for the next three months (T₂ to T₃). These advantages include a decrease in within-subject confounding factors (e.g., age, gender, and hand skills). Also, intragroup comparisons could be made as group II patients continued manual toothbrushing for the entire 6 months of the study (T₁ to T₃) i.e., toothbrushing skill of individual patients could be evaluated.

It was observed that all the three periodontal indices scores i.e, API, SBI and GI increased significantly between T₁ & T₂ time intervals for patients of both the groups [API mean difference= -34.72±17.44, P = 0.000 (group I), mean difference= -29.16±23.08, p value = 0.001 (group II), SBI mean difference= -34.72±17.44, P = 0.000 (group I), mean difference= -36.11±21.39, P = 0.000 (group II), GI mean difference= 0.30±0.08, P = 0.000 (group I), mean difference= 0.29±0.11, P = 0.000 (group II)] and this increase in periodontal indices scores from T1 to T2 time intervals was expected because at T1, they were recorded immediately after oral prophylaxis. All the patients showed satisfactory and similar dexterity for cleaning their teeth using manual toothbrushing.

In group I patients, API and SBI scores improved significantly between T₂ & T₃ time intervals (API mean difference= 13.89±15.39, P = 0.004), SBI mean difference= 9.72 ±15.19, P = 0.020) while GI scores showed no significant difference was found between T₂ & T₃ time intervals (mean difference= 0.02±0.10, P = 0.248). The contrasting results of API & SBI scores being significant between T2 & T3 time intervals while GI scores being insignificant between T2 & T3 time intervals may be due to the fact that the API (Lange, 1977) 8 and SBI (Muhlemann and Son.S, 1971) 9 were evaluated dichotomously being either positive if the plaque/bleeding was present or negative if the plaque/bleeding was absent while GI (Loe and Silness, 1967) 11 was evaluated more specifically with scores ranging from 0-3 with 0= Normal gingiva, 1= Mild inflammation, 2= Moderate inflammation and 3= Severe inflammation. Hence, there was a difference in the method of evaluation of API & SBI as compared to that of GI.

In group II patients, API, SBI and GI scores showed no significant difference between T₂ & T₃ time intervals. (API mean difference= -4.16±9.59, P = 0.08, SBI mean difference= -4.55±11.64, P = 0.015, GI mean difference= 0.04±0.06, P = 0.223). Thus, on intragroup comparison, group I patients showed better cleaning efficiency with powered toothbrushing as compared to the first three months, when these participants were using manual toothbrush while the group II patients showed similar efficiency as they used manual toothbrushing for the entire six months.

In the study by P. Heaseman et al. (1998) 23 no significant difference was found in the reduction of API and SBI score on comparing different types of toothbrushes. Other studies by Lamendola-Sitenga K et al. (1998), 24 Veronique Thienpont et al. (2001) 25 also found no significant difference in reduction of API score on comparing different types of toothbrushes. Yılmaz Zafer Bilen et al. (2021), 26 Lahcen Ousehal et al. (2011) 27 found electric toothbrush to be more efficient than manual toothbrush in improving only the API scores while in the study by Boyd et al. (1989) 28 found electric toothbrush more efficient than manual toothbrushing in improving both the plaque index and bleeding index scores.

Seong-Joon Park et al (2005) 29 found no statistically significant differences in the SBI and GI scores between the electric and the manual toothbrush groups. While some other studies conducted by Heymann P Ho et al (1997) 30 comparing Sonicare sonic toothbrush and a traditional manual toothbrush found reduction of SBI and GI scores was significantly greater in the Sonicare group than in the manual group (P < 0.001).

In the present study, at T₂ time interval, the highest amount of biofilm formation was seen on lower anterior region (78.40±12.60) while the lowest amount of biofilm formation was seen on upper anterior region (32.93±16.74). This can be attributed to the fact that a higher amount of plaque formation is seen in lower anteriors due to salivary proteins. No statistically significant difference (P > 0.05) was observed in the amount of biofilm formation between the two groups in all the four quadrants as well as in the anterior and posterior region of each quadrant. Thus, we can infer from the results that manual toothbrushing was effective in reducing the biofilm accumulation equally in all areas of the oral cavity if the patients are properly trained and they follow correct brushing technique.

As seen at T₂ time interval, the patients in both group I and group II showed the highest amount of biofilm formation on lower anterior region (Group I=71.70±12.34, Group II= 76.88±9.61) and the lowest amount on upper anterior region (Group I=32.49±12.76, Group II= 53.22±18.75) at T₃ time interval also, owing to the similar reason. Statistically significant difference (p<0.05) was observed in the amount of biofilm formation between the two groups in upper and lower left premolar region. This can be attributed to the fact that right-handed subjects are more successful in plaque control of the left quadrants and vice versa 31 and all the participants in current study were right-handed. Group II patients (manual tooth brushing) showed a higher amount of biofilm accumulation in both the regions. Thus, powered toothbrushing was more effective than manual toothbrushing, in reducing the amount of biofilm accumulation around orthodontic brackets, especially on the left premolar regions.

On comparing the amount of biofilm formation in anterior and posterior regions of the groups between T₂ & T₃ time intervals, statistically significant difference was found. Group II patients showed higher amount of biofilm formation in both the anterior and posterior regions (Anterior mean= 12.05±6.90, posterior mean= 10.32±9.75) i.e., patients who used manual toothbrush for the entire 6 months (from T₁ to T₃) after bonding showed higher amount of biofilm accumulation. Thus, we can infer from the results that powered toothbrushing was more effective in reducing the biofilm accumulation around the metal orthodontic brackets in both anterior and posterior regions.

There are no documented studies testing the amount of biofilm accumulation under scanning electron microscope on labial metal orthodontic brackets comparing the efficacy of manual and powered toothbrushing. But other SEM studies have been done evaluating the biofilm formation on different bracket materials i.e., ID Lindel et al (2011) 3 conducted a study to analyse the long-term impact of the bracket material (stainless steel and ceramic) on the extent of biofilm coverage under clinical conditions. They found that ceramic brackets exhibit less long-term biofilm accumulation than metal brackets. SB Yener et al (2020) 6 conducted a study to evaluate and compare the biofilm formation between labial and lingual orthodontic brackets. Total biofilm formation was 41.56% (min 29.43% to max 48.76%) on lingual brackets and 26.52% (min 21.61% to max 32.71%) on labial brackets. the biofilm accumulation on lingual orthodontic therapy was found to be more than labial orthodontic therapy. No difference was observed in intraoral location.

Limitations of the Study

Even after meticulous planning and precise execution of designed study some shortcomings are inevitably anticipated. Following are some of the limitations:

Conclusion

It can be concluded that powered toothbrushes are more effective in removing plaque and thus reducing gingival inflammation in patients with fixed orthodontic appliances. Orthodontists should also focus on increasing patients’ awareness regarding the importance of oral hygiene maintenance and professional oral prophylaxis undergoing fixed orthodontic treatment.

Source of Funding

None.

Conflict of Interest

None.