Efficacy of an electric toothbrush on plaque control compared to two manual toothbrushes

Abstract

Objectives: This study aimed to compare an electric toothbrush with two manual toothbrushes, in their relative efficacy to control plaque. Design: Randomised clinical trial. Setting: Kerman Dental School, Iran. Participants: Forty-five volunteer dental students were randomly assigned to one of three groups. All subjects received a baseline plaque assessment using O’Leary plaque index, and then a prophylaxis to achieve the plaque index of zero. Subjects were trained to brush twice daily, with their assigned device and return after 1 week and then after 2 weeks for plaque assessment. Chi-squared and ANOVA were mainly used. Main outcome measure: Plaque assessment using O’Leary plaque index. Results: Although Jordan toothbrush consistently resulted in lower plaque indices compared to both manual toothbrushes, those differences were not statistically significant, F(2, 42) = 2.45, P = 0.10. Plaque reduction from week 1 to week 2 was significant in Jordan Power group (60%, from 13.46 to 5.44, P = 0.010) and Panbehriz Classic group (53%, from 20.92 to 9.91, P = 0.007). Conclusion: The results of this study shows no evidence of statistically significant difference in respect to plaque control, between Jordan Power electric toothbrush and either of Oral-B Advantage or Panbehriz Classic manual brushes in a group of dental students after 2 weeks.

INTRODUCTION

The role of dental plaque accumulation in the development of dental caries and periodontal diseases is well established; thus its removal is critical for the long-term maintenance of oral health1., 2.. Regular tooth brushing remains as the major method of plaque removal¹. Since the introduction of electric toothbrushes in 1960, there have been many changes in their design aimed at improving plaque removal. Those currently available vary greatly in brush head design, filament pattern and speed and type of motion1., 2.. Their decreasing prices, together with increased general awareness of oral health, have led to expansion of using such toothbrushes all over the world1., 3..

As new designs of powered toothbrushes are introduced every so often, the need for clinical evidence increases as to which kind of toothbrush is the most effective in plaque control and oral health improvement. Increasingly, clinical trials indicate some electric brushes have greater efficacy on plaque removal than other toothbrushes1., 2., 3..

Several studies have compared plaque removal and other oral health indices with electric and manual toothbrushes3., 4., 5., 6., 7., 8., 9., 10., 11., 12., 13., 14., 15., 16., 17., 18., 19., 20., 21., 22., 23., 24., 25., 26., 27., 28., 29., 30.; the results are controversial. Some trials have shown some electric brushes with certain features are superior to other power toothbrushes3., 4., 5., 6., 7.. Many electric toothbrushes have been shown to be more effective plaque removers than manual brushes6., 7., 8., 9., 10., 11., 12., 13., 14., 15., 16., 17., 18., 19., 20., especially in proximal¹⁰ and supra-gingival¹² surfaces. Some trials have found manual toothbrushes more effective than electric toothbrushes²³. A recent in-vitro study concluded that power or sonic toothbrushes may lead to significantly higher loss of demineralised enamel compared to manual control²⁴. On the other hand, many studies were unable to show any significant difference regarding plaque index between the manual and electric toothbrushes25., 26., 27., 28.. There is a fast growing demand in some developing counties, such as Iran, for the utilisation of use of available foreign and homemade oral health products. Dental professionals are always confronting patients with questions regarding using available electric toothbrush and some brand of manual toothbrushes that are either foreign or Iranian. In addition, there is a big difference between prices of these products in market; range from $20 (200,000 rials) to $2 (20,000 rials) and it is very important to justify the use of the products through an evidence-based approach.

The present study was designed to compare the efficacy of the Jordan Power toothbrush to control plaque with two commonly used manual toothbrushes, namely Oral-B Advantage toothbrush and Panbehriz Classic toothbrush (which are the most available toothbrushes in Iran) over a 2-week period.

MATERIALS AND METHODS

Study population

Subjects were recruited from preclinical dental student volunteers of Kerman University. Eligible participants were non-smokers, had good general health and 28 teeth (not including third molars). Exclusion criteria included: any systemic diseases (e.g. diabetes mellitus) or physical limitation or restriction that might preclude normal oral hygiene; use of any medication (e.g. oral contraceptives); pregnancy; presence of orthodontic appliances or implants; crowding of the teeth; overhangs and large restorations; crowns or bridges; pockets more than 4 mm depth. All subjects had to refrain from other oral hygiene procedures, such as inter-dental cleaning products, chewing gums, and mouth rinses for the duration of the study. All subjects gave written informed consent to their participation before the study commenced.

Study design

A randomised, examiner-blind, parallel group design was carried out over a 2-week period in the Periodontology Department of Dental School of Kerman University of Medical Sciences in Iran. The study design was ratified by the Ethics Review Board of the University prior to commencement. No toothbrush manufacturer either directly or indirectly sponsored the trial but the companies’ representatives were informed about the trial when they were asked to supply their product for the study (Farshid dental product supplier, Kerman, Iran).

Consecutive sampling was conducted in order to recruit dental students who volunteered in response to an advertisement. At a baseline assessment, subjects who had refrained from all hygiene procedures in the preceding 10 hours and from eating in previous 4 hours were examined in order to determine if they were eligible and received a baseline plaque measurement. Prophylaxis and polishing were performed to achieve the same plaque index of zero for all qualified subjects.

Eligible subjects were then randomised into three groups by sealed envelope method: Jordan Power electric toothbrush (Norway) with soft end-rounded bristles and rotation oscillation action, Oral-B Advantage manual toothbrush (USA), or Panbehriz Classic manual toothbrush (Iran). After acceptance of a subject, an envelope was opened; the card inside directing to which group the participant was allocated.

When brushing manually, the subjects received instruction in the Bass technique. For the electric toothbrush they were asked to brush in accordance with instructions provided by the manufacture, a copy of which was supplied to each. They were provided with the same toothpaste (Crest Complete 7) and brushed twice daily, each timed for 2 minutes. All subjects returned after 1 week and then after 2 weeks of product use for a repeat plaque assessment, having refrained from all hygiene procedures in the preceding 10 hours and from eating in the previous four hours.

Clinical assessments

Clinical evaluations were performed by two trained and calibrated examiners (weighted Kappa = 89%) who were kept blind to the products and group allocations. Before each follow-up examination, the study coordinator reminded all participants not to reveal their group assignment to the examiners. Plaque was evaluated using the O’Leary method³¹. Examiners were unaware of previously given plaque scores. The mean of two examiner-obtained measures constituted the final plaque index. Participants were kept unaware of their plaque index.

Statistical methods

The study intended to test the hypothesis that in a group of trained dental students there is no significant difference between manual and electric toothbrush plaque removal efficacy. A sample size of 15 subjects per group was estimated for this study based on a previous study of a similar design¹⁶. O’Leary plaque indices after 1 and 2 weeks of product use were the outcome measures.

Baseline distributions between treatment groups were compared for age and plaque scores using analysis of variance (ANOVA) and for gender using chi-squared test. Plaque indices were expressed as means and standard deviations (SD). Within each treatment group, the follow-up scores were analyzed using a paired t-test. The groups were compared for plaque indices using a repeated measure ANOVA; in order to better fit the model’s assumptions, all plaque scores were transformed to square-root. If there were significant differences, Tukey HSD test was used to explore further to see where the differences lay. Values of P < 0.05 were considered statistically significant. Re-analysis with non-parametric tests showed no evidence of differences from the present results.

RESULTS

Of 45 enrolled subjects (20 males, 25 females), none withdrew prematurely (Figure 1). The mean age of the subjects was 20.8 ± 1.7 years (range, 18–29 years). The treatment sequence groups were well balanced; there was no significant difference in respect of gender, age, or baseline plaque index (Table 1).

Figure 1.

Flow of participants through each stage.

Table 1.

Baseline demographic and clinical characteristics of groups

	Jordan Power (n = 15)	Panbehriz Classic (n = 15)	Oral-B Advantage (n = 15)	P-value between groups
Age (year, mean ± SD)	21.2 ± 2.3	20.3 ± 1.0	20.9 ± 1.6	0.33* NS
Gender (female/male)	10/5	9/6	6/9	0.31† NS
Baseline PI (mean ± SD)	43.46 ± 17.20	49.14 ± 21.92	51.61 ± 20.86	0.25* NS

SD, standard deviation; NS, non-significant; PI, plaque index.

^*One-way analysis of variance.

^†Chi-squared test.

As illustrated in Figure 2, plaque scores in the Jordan Power group were consistently lower over the 2-week period; average plaque index clearly decreased after the first week of brushing in all groups, and variation in performance decreased over time, especially in the Jordan Power group. However, analysis of the results demonstrated no statistically significant difference between groups regarding plaque index after 2 weeks of brushing, F(2, 42) = 2.45, P = 0.10.

Figure 2.

Plot of model estimated means for the three toothbrush groups for each of the three visits of the study (consider that all plaque indices were zeroed after baseline assessment).

There was a statistically significant reduction in the scored plaque index between week 1 and week 2 in the Jordan Power group (from 13.46 to 5.44, P = 0.010), representing a 60% reduction. There was also a significant 53% reduction in the plaque index in the Panbehriz Classic group (from 20.92 to 9.91, P = 0.007). There was a 44% reduction in plaque index in the Oral-B Advantage group (from 15.00 to 8.46), however it was not statistically significant (P = 0.64); note Table 2. The 95% confidence intervals for the mean differences of the mean differences between week 1 and 2 for each group are shown in Table 2.

Table 2.

Comparison between plaque index means

	Jordan Power (n = 15)	Panbehriz Classic (n = 15)	Oral-B Advantage (n = 15)	Total (N = 45)
Baseline PI (mean ± SD)	43.46 ± 17.20	49.14 ± 21.92	51.61 ± 20.86	49.74 ± 20.37
Week 1 PI (mean ± SD)	13.46 ± 10.41	20.92 ± 14.17	15.00 ± 11.34	16.46 ± 12.24
Week 2 PI (mean ± SD)	5.44 ± 2.01	9.91 ± 5.31	8.46 ± 6.31	7.94 ± 5.16
95% CI for diff. week 1–week 2	(2.24, 13.81)	(3.49, 18.53)	(−0.43, 13.50)	(4.88, 12.17)
Paired t-value*	2.98	3.14	2.01	4.71
P-value	0.010*	0.07*	0.64 NS	<0.001*

SD, standard deviation; NS, non-significant; PI, plaque index.

^*Paired t-test for comparison between means at week 1 and week 2 for each group separately.

DISCUSSION

In the present study a commonly used electric toothbrush with rotation oscillation action, Jordan Power, was compared to two conventional manual brushes with different design, Oral-B Advantage and Panbehriz Classic. The results of this 2-week parallel group study shows that in a group of dental students trained in brushing technique, there was no significant difference in plaque indices between the electric toothbrush and either of the two manual toothbrushes.

One commonly used method to compare toothbrushes in respect to plaque control, is to consider a period during which all participants abstain from all oral hygiene procedures to allow accommodation of plaque, and then see how different brushes reduce the plaque index. However, we conducted a different approach in the current study by reducing the plaque index of all eligible participants to zero before brushing and then evaluating the efficacy of brushes in plaque control. We also enrolled dental students who because of their motivation, field of study and skills have the optimum competence and compliance for perfect brushing.

There is overwhelming evidence that electric toothbrushes are more effective plaque removers when compared to manual brushes6., 7., 8., 9., 10., 11., 12., 13., 14., 15., 16., 17., 18., 19., 20.. Systematic reviews have shown that electric toothbrushes with rotation oscillation action removed plaque and reduced gingivitis more effectively than manual brushes; no other powered designs were as consistently superior to manual toothbrushes1., 2.. Nevertheless, results from some clinical trials were not able to demonstrate any significant differences in plaque removal between power brushes with rotation oscillation action and manual brushes25., 27., 28.. Moreover, some manual toothbrushes have been found more effective than electric toothbrush both in clinical trials²³ and in in-vitro studies²⁴.

It is generally believed that if manual tooth brushing is performed correctly as instructed and for a sufficient duration of time, adequate plaque removal is achievable1., 4.. However, seemingly many tooth-brushers fail to brush effectively or on a regular basis⁴. On the other hand many features may assist the cleaning efficacy of an electric toothbrush to be more effective, particularly on difficult to access surfaces; these key features include: specially designed brush head which allows easier access to all surfaces; 3D motion features which improve interdental penetration; pressure control systems; built-in timer; etc. When compared to manual toothbrushes, electric toothbrushes require less manual dexterity and brushing skills. The novelty effect also is another issue of concern in power toothbrushes; some effects are likely to appear in the short-term that may not be sustained over the long run.

With adequate plaque reduction, the average time spent brushing is considered as more important than how often it is performed per day³². The major amount of plaque removal is reachable after 30 seconds of brushing per quadrant³³. Most trials consider a duration of 2 minutes for tooth brushing, and many use a timer and diaries to guarantee sufficient brushing, however, discrepancies between actual and estimated tooth brushing time are reported32., 33.. In the long-term it can deteriorate further, as a telephone survey conducted 6 months after the commencement of one study indicated that most subjects were not using the device twice a day as they had during the study²⁰.

To our knowledge very few studies have investigated the efficacy of toothbrushes in dental students or dental professionals; typically these two groups are prohibited from participating in such studies. One study consisting of dental students was unable to show a significant difference between manual brushing and any of two tested electric brushes in respect to plaque removal²⁸. This has been demonstrated in the current study; as trained dental students and dental professionals are probably the most efficient brushers, adequate plaque removal is achievable with correct and regular brushing with either manual or electric toothbrushes.

In our study there was relatively large plaque accumulation after the first week of brushing, which decreased significantly in all groups, except Oral-B in the following week. Seemingly our subjects required a period for familiarisation with the use of their assigned products. In the Oral-B group though there was also a 43% reduction in mean plaque index, but it was insignificant; it is likely that participants required less time to get familiar to the product in the Oral-B group so the results after 1 week are not significant compared to the second week.

Compared to size and duration of this trial the general population is much larger and more diverse, and brushing continues for much longer time. Although tooth brushing is primarily focused on controlling plaque, its main purpose in the long-term is to maintain good gingival health. Hence as well as plaque removal efficacy, clinical assessment and comparison should encompass investigation of their influence on gingival health. Thus, studies of larger scale and duration are required to fully evaluate the effects of electric toothbrushes on plaque control and gingival health indices. Studies with crossover design and samples recruited from general populations as well as dental professionals would provide additional information on efficacy of training and brushing methods when comparing toothbrushes. Moreover, cost-analysis trials are necessary to establish a more clear recommendation.

CONCLUSION

It is concluded that there is no significant difference in respect to plaque index, between the Jordan Power electric toothbrush, and either the Oral-B Advantage or Panbehriz Classic manual brushes after 2 weeks of use in a group of dental students.

Acknowledgements

The authors wish to sincerely thank all students who participated in the study. This study was supported by a grant from the Vice chancellor for research, Kerman University of Medical sciences.