Effect of electric toothbrushes versus manual toothbrushes on removal of plaque and periodontal status during orthodontic treatment

ORIGINAL ARTICLES

Effect of electric toothbrushes versus manual toothbrushes on removal of plaque and periodontal status during orthodontic treatment L. M. Trimpeneers, DDS, PhD, a I. A. Wijgaerts, DDS, b N. A. Grognard, DDS, b L. R, Dermaut, DDS, PhD, ~ and P. A. Adriaens, DDS, PhD b

Gent and Brussels, Belgium This study compared the effectiveness of three different types of electric toothbrushes, i.e., Interplak, Philips, and Rotadent, with a manual multitufted toothbrush (Blend-a-Med), in removing supragingival plaque and in preventing the development of gingivitis in adolescent patients with fixed orthodontic appliances. A single blind, cross-over, clinical trial was carried out in 36 adolescent patients, randomly divided into four equal groups. Every group tested each type of toothbrush, in a different sequence. Plaque and gingival scores were recorded at baseline and after 1 and 2 months of the test period. All patients received a professional prophylaxis after each clinical evaluation, except during the test period. The analysis of the data was performed with the nonparametric Friedman test. The results demonstrated, in essence, for all parameters that the manual toothbrush was the most effective. Of the three electric toothbrushes tested, the Philips toothbrush seemed to give slightly better results than the Interplak toothbrush, whereas Rotadent very clearly gave results inferior to all others. Personal preference on the four toothbrushes used revealed that the group as a whole least preferred a manual brush. However, the answers on the questionnaire did not always show a logical consistency. Therefore it should be interpreted with some caution. (Am J Orthod Dentofac Orthop 1997;111:492-7.)

T h e role of dental plaque accumulation in the cause of dental caries and periodontal diseases is well established? -3 Orthodontic patients, especially adolescents, often show ineffective plaque control, because of difficulties in performing oral hygiene with fixed orthodontic appliances in place. 4'5 Orthodontic appliances protect the dental plaque from the mechanical action of brushing and mastication. 6 Undisturbed supragingival plaque accumulation initiates gingival inflammation. 17 Gingivitis, together with gingival hyperplasia, is often observed during orthodontic treatment. 8 These pathologic changes reflect the onset of a destructive process in the periodontium. 9 Orthodontic patients, treated with fixed appliances, are also at increased risk for white spot formation (decalcification) on the coronal surfaces aAssistant professor, Department of Orthodontics, University of Gent. bAssistant professor, Department of Periodontology, University of Brussels. aChairman, Department of Orthodontics, University of Gent. bChairman, Department of Periodontology, University of Brussels. Reprint requests to: Prof. Dr L. R. Dermaut, Department of Orthodontics, University of Gent, Dental School, De Pintelaan 185, B-9000, Gent, Belgium. Copyright © 1997 by the American Association of Orthodontists. 0889-5406/97/$5.00 + 0 8/1/71174

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of bonded or banded teeth. 1°-12In an earlier clinical study 13 an overall decalcification rate from 10.0% to 12.7% was found. Although mouthwashes may be helpful in helping to reduce dental plaque formation, 4'7'14 and although the application of topical fluorides is one of the most effective caries preventive methods, 1517 optimum mechanical removal of plaque by oral hygiene procedures is the most important factor during orthodontic treatment. Several electric toothbrushes have been developed in an attempt to improve brushing efficacy. Only a limited number of studies have evaluated their efficacy in orthodontic patients, comparing electric toothbrushes with manual toothbrushing. The results from these studies are conflicting. In addition, most of those clinical studies compared only limited numbers of orthodontic patients and short observation periods. Therefore the aim of this study was to compare the efficacy of three different types of electric toothbrushes, i.e., Interplak (Bausch & Lomb), Philips (Philips), and Rotadent (Novitas), with a manual multitufted toothbrush (Blend-a-Med, Proctor & Gamble), in removing supragingival plaque and in preventing the development of gingivitis in adolescent patients with fixed orthodontic appliances.

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Table II, Plaque Index brackets

Table I. Bleeding Index

Score

Description

Score

Description

No bleedingafter probingwithin 10 seconds. Point bleedingafter probingwithin 10 seconds. Abundantbleedingafter probingwithin 10 seconds.

0 1 2 3

No plaque Islands of plaque Continuous line --< 1 m m in width Continuous line > 1 m m in width

MATERIAL AND METHODS Study Design A single blind, crossover, clinical trial was carried out in adolescent patients from a private orthodontic practice. The study was initiated in January 1992 and was completed in March 1993, with an interruption of 2 months during the summer holidays (July and August) in 1992. The protocol was reviewed and approved by the Ethics Committee of the University of Brussels. Written informed consent was obtained from the parents before the enrollment of their child in the study. Study Population

The study population consisted of 36 systemically healthy patients with a mean age, at the start of the study, of 12 years and 10 months (range: 11 years and 5 months to 15 years and 2 months). Nineteen girls (mean age: 12 years and 7 months) and 17 boys (mean age: 13 years and 1 month) participated in the study. During the course of the study, one boy was withdrawn because of lack of compliance with orthodontic treatment. All patients were treated by the same orthodontist (L.T.), with fixed appliances on both upper and lower dental arches. All teeth were bonded with unipoint contact brackets on laminated minimesh, except for the first molars, which received bands cemented with Aquacem glass ionomer cement (De Trey, Dentsply).

Clinical Assessments At each visit, the scoring was performed by three examiners according to a single blind protocol. Each examiner scored the same parameter during the entire course of the study. Teeth without brackets (according to the treatment plan) were not scored. Modified Gingival Index is (GI). All buccal and lingual marginal units, as well as all buccal and lingual papillary units of all permanent incisors, canines, premolars, and first molars in the upper and lower jaws were examined. This GI was scored by a single calibrated examiner (N.G.). Bleeding on Probing Index (BI). A Florida Probe a9 with a standardized probing force (0.25 N) was used by a single calibrated (properly trained) examiner (I.W.) for all measurements throughout the entire study. Probing was performed at six sites around each tooth, i.e., the midbuccal and midlingual sites, as well as at the mesial and distal line-angles on the buccal and lingual aspects of the interdental surfaces. The probe was inserted along the long axis of the tooth until the 0.25 N force was reached.

For each site, a score between 0 and 2 was given (Table I). When the probe could not be inserted along the long axis of the tooth, no score was given. This mainly occurred for several buccal surfaces, where the orthodontic brackets interfered with probing. Plaque Index 2° (PI). With a cotton pellet, a 4% erythrosin disclosing solution (Diaplac, OY M61nlycke AB) was applied to all tooth surfaces. To have standardized amounts of staining solution, one pellet was used to disclose one arch. Both the PI and the Plaque Index around the brackets were recorded by the same calibrated examiner (L.T.) throughout the entire study. Plaque Index brackets (PIb). Because fixed orthodontic appliances create specific areas for plaque retention, a PI was designed to evaluate the amount of plaque on and around the brackets. A score from 0 to 3 was given (Table II).

Toothbrushes Four brushes (three electric and one manual) were evaluated in this clinical study: Interplak, Philips, Rotadent (with hollow cup-shaped brush), and the Blend-a-Med Dental Plus Junior toothbrush with medium stiffness.

Course of the Study The 36 patients were randomly divided into four equal groups. Each patient (except one boy) used all four different brushes (three electric and one manual), but in a randomly designed sequence. Each experimental period lasted for 2 months, with a score taken at baseline, month 1, and month 2. Between each experimental period, a 1-month "wash-out" period was inserted, during which the manual toothbrush was used by all participants to return to comparable baseline values. During this month, all patients brushed according to the instructions given at the start of the orthodontic treatment. At baseline and after 1 and 2 months, all clinical parameters were measured. After the baseline and month 2 scoring, all patients received a professional prophylaxis comprising a supragingival and subgingival scaling with ultrasonic and hand instruments, followed by a polishing of all tooth surfaces with prophy brushes (Haw6-Neos Dental) and Uni-Pro (Henry Schein, Inc.) polishing paste containing 1.23% of fluoride phosphate. The polishing paste with the finest particle size was used. During the study, all patients used the same Blend-a-

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Table IIh Levels of significance and corresponding points

Table IV. Between brush-effect on baseline for all parameters

(mean) p-value

Points Manual

p 0.02 < p 0.01 < p 0.005 < p p

> 0.05 -< 0.05 -< 0.02 -< 0.01 -< 0.005

0 1 2 3 4

Gingival Index Bleeding Index Plaque Index Plaque Index brackets

1.38 0.47 1.07 1.35

Interplak Philips Rotadent 1.36 0.45 1.10 1.35

1.38 0.44 1.03 1.26

1.40 0.44 1.18 1.33

p-value 0.08 NS 0.10 NS 0.06 NS 0.75 NS

p > 0.05: nonsignificant (NS).

Med dentifrice (Procter & Gamble) containing sodium fluoride (NaF) (1450 ppm F ) . At the start of their orthodontic treatment, the patients were instructed by the orthodontist to brush according to the modified Bass method. After the prophylaxis, all patients received their randomly assigned toothbrush. For the manual toothbrush, no further instructions were given. For the use of the electric toothbrushes, the patients were instructed to brush according to the manufacturer's instructions, a copy of which was supplied to each of them. Patients were asked to brush twice daily, i.e., in the morning and in the evening. According to the literature, the efficacy of plaque removal differs for each toothbrush. However, for each individual toothbrush, the plaque removing efficacy increases with the brushing time. The major part of the plaque removing effect is reached after 30 seconds of brushing per quadrant. 21 Other investigators 22'23 standardized the duration of toothbrushing to 2 minutes. Because of the increased plaque retention, oral hygiene is even more time-consuming when fixed orthodontic appliances are in place. The brushing time in our study was arbitrarily set at 3 minutes. Considering the fact that the duration of toothbrushing was standardized, it is questionable whether it is equitable to state that one brush performs "better" than another. 24 It was not the purpose of this study to test this parameter. Therefore the time factor was standardized at 3 minutes, by means of a countdown stopwatch, provided to each patient at the start of the study. Every second week, the manual toothbrushes and the brushheads of the electric toothbrushes were replaced. At the end of each test period, the patients were asked to return their used brushes or brushheads to check their compliance. Cooperation was encouraged by means of some presents as reward and pocket money for the children. When all patients had completed two test periods, there was an interruption of 2 months during the summer holidays. During this 2-month period, the patients were asked to brush with the manual toothbrush as instructed before the start of the orthodontic therapy. After the summer holidays, two test periods of 2 months, each preceded by 1 month of wash-out, were completed. All patients were told to refrain from using dental floss, interproximal brushes, or other hygiene aids during the entire course of the study. They were requested to have routine dental examinations with their general dentists every 6 months. They were not allowed to receive topical fluoride applications, neither to rinse with Fsolutions nor any oral antiseptics.

The intake of medication was recorded from a record kept by each patient. All patients were asked to fill out a questionnaire to evaluate the subjective findings of each patient concerning the toothbrush they had used in the previous period. When they had finished the test periods, they were asked to make a comparison between the four toothbrushes and to rank them, starting with the toothbrush they preferred.

Statistical Analysis The analysis of the data was performed with the nonparametric Friedman's test. A between-brush effect was analyzed for each parameter at baseline, at month 1 and at month 2. Statistical significance was accepted for p -< 0.05. We divided the levels of significance into five categories, and points from 0 to 4 were given to each category (Table III). Whenever two toothbrushes were statistically significantly different, the brush with the lowest rank, determined by the Friedman's test, was given the point. To determine the "best" toothbrush, the four brushes were ranked according to the sum of their points; the highest sum indicated the most effective toothbrush.

RESULTS T h e overall results for the different parameters at baseline are listed in Table IV. N o statistical differences were f o u n d a m o n g the four groups. To look f o r the differences f o u n d at m o n t h I and m o n t h 2, the brushes were c o m p a r e d two by two for all parameters. Points were given to the best brushp e r f o r m a n c e according to the level of significance. The results are represented in Tables V and VI. A t m o n t h 1, no statistical differences were f o u n d a m o n g the toothbrushes for the gingival index (all points were zero). As c o m p a r e d two by two, no differences were f o u n d for any of the p a r a m e t e r s between the m a n u a l and the Interplak toothbrush, as well as between the Interplak and the Philips toothbrush. T h e m a n u a l toothbrush showed better p e r f o r m a n c e than the Philips t o o t h b r u s h in plaque removal (PI), but the reverse for the latter one that scored better for the bleeding index (BI). W h e n e v e r in comparison with the R o t a d e n t toothbrush, the

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Table V. Short-term effect between all brushes for all

Table VI. Long-term effect between all brushes for all

parameters (month 1-score)

parameters (month 2-score)

Significance

Points (best)

Significance

[

Points (best)

ManuaI-InterpIak

GI: 0.54 BI: 0.16 PI: 0.52 PIb: 0.71

0 0 0 0

Manual-Interplak

GI: 0.22 BI: 0.41 PI: 0.03 PIb: 0.05

0 0 1 (Manual) 0

Manual-Philips

GI: 0.79 BI: 0.00 PI: 0.00 PIb: 0.08

0 4 (Philips) 4 (Manual) 0

Manual-Pbilips

GI: 0.14 BI: 0.03 PI: 0.00 PIb: 0.13

0 1 (Philips) 4 (Manual) 0

Manual-Rotadent

GI: 0.68 BI: 0.05 PI: 0.59 PIb: 0.00

0 1 (Manual) 0 4 (Manual)

Manual-Rotadent

GI: 0.00 BI: 0.36 PI: 0.04 PIb: 0.00

4 (Manual) 0 1 (Manual) 4 (Manual)

Interplak-Philips

GI: 0.86 BI: 0.13 PI: 0.09 PIb: 0.23

0 0 0 0

Interplak-Philips

GI: 1.00 BI: 0.13 PI: 0.50 PIb: 0.63

0 0 0 0

Interplak-Rotadent

GI: 0.95 BI: 0,00 PI: 0.84 PIb: 0.00

0 4 (Interplak) 0 4 (Interplak)

Interplak-Rotadent

GI: 0.04 BI: 0.09 PI: 0.92 PIb: 0.00

1 (Interplak) 0 0 4 (Interplak)

Philips-Rotadent

GI: 0.81 BI: 0.00 PI: 0.23 PIb: 0.02

0 4 (Philips) 0 i (Philips)

Philips-Rotadent

GI: 0.07 BI: 0.00 PI: 0.50 PIb: 0.00

0 4 (Philips) 0 4 (Philips)

9 Manual 9 Philips 8 Interplak 0 Rotadent

Overall total

Overall total

GI: GingivaI Index. BI: Bleeding on Probing Index. PI: Plaque Index. PIb: Plaque Index brackets.

p-value indicated significance, this toothbrush demonstrated the poorer results. Whenever the manual toothbrush differed significantly from another toothbrush, the manual toothbrush performed better, except for the BI, compared with the Philips toothbrush, as previously mentioned. At month 2, almost all short-term tendencies were confirmed. According to Tables V and VI, in general, the manual toothbrush did not rank higher for the B I s compared with the electric toothbrushes. As far as the PI is concerned, the differences were obvious, i.e., a higher ranking for the manual toothbrush. In the overall ranking, the manual toothbrush performed as well as the Philips toothbrush after the first month. At the end of the experimental period (2 months), it had the highest ranking. The Rotadent toothbrush was found to have the lowest ranking throughout the entire experimental period. In answer to the questionnaire, all patients made

495

14 Manual 9 Philips 5 Interplak 0 Rotadent

a comparison on preference among the four brushes they had used and ranked them, starting with the brush they preferred. Their subjective scores are given in Table VII. DISCUSSION

No significant differences were found between the groups for baseline clinical indices. This indicates that the randomly divided groups were homogeneous, and that a 1-month "wash-out" period brought all participants to a comparable baseline. Of all parameters tested, the GI seemed to show the lowest value in comparing the effectiveness of toothbrushes, because this index revealed no statistical differences between the toothbrushes at month 1, and only few points were scored at month 2 for this parameter. After each test period, the patients conscientiously responded to a set of questions; the answers, however, did not always show a logical consistency, so the results were interpreted with caution and most of them were not published. Several investigators have evaluated the efficacy of electric toothbrushes compared with manual

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Table VII. O r d e r of preference: subjective score given by patients at the end of trial 1. Girls: Philips > Manual > Interplak = Rotadent 2. Boys: Philips > Interplak > Rotadent > Manual 3. Group: Philips > Interplak > Rotadent > Manual

ones. Very few, however, reported on the effect in orthodontic patients and none on four different toothbrushes in the same clinical study over a long trial period in a larger study population. A series of clinical trials assessed the efficacy of the Interplak electric toothbrushY -29 Although the results of these trials suggest that the plaque removal with an Interplak electric toothbrush may be superior to manual toothbrushing, they must be considered with caution. Each study suffered from one or more of the following drawbacks: lack of controls and an extremely short trial period, nonrandom assignment of treatment, or lack of a blind examiner.23 In a short-term study in a group of periodontal patients, Killoy et al.3o found the Interplak electric toothbrush to be more efficient than the manual one, with a mean plaque reduction of 70% for the Interplak electric toothbrush and 65% for the manual one. During orthodontic therapy, Wilcoxon et al. 31 compared the long-term efficacy of the Interplak electric toothbrush to the plaque-removing efficacy of a manual orthodontic toothbrush (Oral-B 15) with soft bristles. Plaque and gingival scores were significantly lower after brushing 2 months with the counterrotational power brush (Interplak). This finding was irrespective of the sequence in which the brushes were used. The efficacy in plaque removal of the Interplak electric toothbrush was also compared with the plaque-removing efficacy of a multitufted manual toothbrush (Oral-B 40) in a patient population of 30 healthy patients by Ciancio and Mather. 32 The results demonstrated a significantly lower PI for the Interplak. Because of the very short experimental period (2 weeks) and the novelty of the power brush, which may have influenced the use of this device by the users, these results should also be interpreted with caution. Besides plaque removal and relatively shortterm periodontal status, it is worth paying attention to the potential abrasiveness of the electric brushes on enamel and dentin. From an in vitro study,33 it appears that the Interplak is no more abrasive than a manual multitufted brush. However, in vivo studies on soft tissue, abrasiveness has yet to be reported. As originally designed, the Rotadent electric

American Journal of Orthodontics and Dentofacial Orthopedics May 1997

toothbrush has been tested in dental students over a 14-day period, but failed to be more effective in removing dental plaque than a conventional toothbrush. 33 After the design and texture of the bristles were modified, in the hands of 40 adult periodontal patients, this brush proved to be just as effective as an oral hygiene kit. 34 Murray et al. 35 evaluated the microbiologic effect of the Rotadent in 40 subjects who had received periodontal treatment and concluded that " . . . the rotary tooth cleaner and conventional toothbrushing are equally effective in controlling gingivitis and fostering a less pathogenic microflora." The clinical results of the same study material indicate that " . . . the Rotadent is as efficient for plaque removal and control of gingival inflammation as a combination of conventional toothbrushing, flossing, and toothpicks for patients in periodontal maintenance. ''36 Forty adolescent orthodontic patients entered another clinical trial during an 18-m0nth study period. 3v The findings suggest that the Rotary electric toothbrush is more efficient than conventional toothbrushes for removing plaque and controlling gingivitis in adolescents during orthodontic treatment. CONCLUSION

In conclusion, in studies on efficacy of toothbrush performance, conflicting results are still encountered. A partial explanation for this confusion can be the fact that perfectly controlled clinical studies on oral hygiene are nearly impossible to perform because of the numerous influencing factors involved. In addition to this variability in the studies, the lack of a standard experimental set-up makes comparison exceedingly difficult? 8 With respect to these problems, Ash39 advocated (a) long-term studies to help offset the novelty effect, (b) use of numerical indices to provide for objective statistical evaluation of results, (c) use of as many criteria as possible to evaluate efficacy, and (d) use of an experimental method that controls for obtaining similar and comparable experimental groups. In the current study, we developed a design in accordance with these suggestions. We concluded after evaluation of the short-term (1 month) and long-term (2 months) results that the manual toothbrush was the most efficient in removing supragingival plaque in adolescent patients with fixed orthodontic appliances. Of the three electric toothbrushes tested, the Philips toothbrush seemed to give slightly better results than the Interplak toothbrush, whereas Rotadent very clearly gave results inferior to all others. We thank the companies Braun, Deprophar, Hospithera, and Procter & Gamble for supporting the study. We

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also gratefully acknowledge the assistance of our colleagues M. Moradi Sabzevar, S. Lamoral, and C. Mertens in taking care of the professional prophylaxis to all patients at the start of each test period, as well as Mrs. B. Jouret for typing the manuscript. REFERENCES 1. L6e H, Theilade E, Jensen SB. Experimental gingivitis in man. J Periodontol 1985;36:177-87. 2. Lindhe J, Hump SE, LOe H. Plaque-induced periodontal disease in beagle dogs. J Periodont Res 1975;10:243-55. 3. Suomi JD, Doyle J. Oral hygiene and periodontal disease in an adult population in the United States. J Periodontol 1972;43:677-81. 4. Zachrisson BU. Cause and prevention of injuries to teeth and supporting structures during orthodontic treatment. Am J Orthod 1976;69:285-300. 5. Boyd RL. Longitudinal evaluation of a system for self-monitoring plaque control effectiveness in orthodontic patients. J Clin Periodontol 1983;10:380-8. 6. Brightman LJ, Terezhalmy GT, GreenwelI H, Jacobs M, Enlow DH. The effects of a 0.12% chlorbexidine g~uconate mouth rinse on orthodontic patients aged 11 through 17 with established gingivitis. Am J Ortbod Dentofac Orthop 1991;100: 324-9. 7. Theilade E, Wright WH, Jensen SB, L6e H. Experimental gingivitis in man. J Periodont Res 1966;1:1-13. 8. Morrow D, Wood DP, Speechley M. Clinical effect of subgingival chlorhexidine irrigation on gingivitis in adolescent orthodontic patients. Am J Orthod Dentofac Orthop 1992;101:408-13. 9. Diamanti-Kipioti A, Gusberti FA, Lang NP. Clinical and microbiological effects of fixed orthodontic appliances. J Clin Periodontol 1987;14:326-33. 10. Gorelick L, Geiger AM, Gwinnett AJ. Incidence of white spot formation after bonding and banding. Am J Orthod 1982;81:93-8. 11. Mizrahi E. Surface distribution of enamel opacities following orthodontic treatment. Am J Orthod 1983;84:323-31. 12. Zachrisson BU, Zachrisson S. Caries incidence and orthodontic treatment with fixed appliances. Scand J Dent Res 1971;79:183-92. 13. Trimpeneers LM, Dermaut LR. A clinical evaluation of the effectiveness of a fluoride-releasing visible light-activated bonding system to reduce demineralization around orthodontic brackets. Am J Orthod Dentofac Orthop 1996;110:218-22. 14. Miller RA, Melver JE, Gunsolley JC. Effects of sanguinaria extract on plaque retention and gingival health. J Clin Orthod 1988;5:304-7. 15. Seppa L, P6ll~ihen L. Caries preventive effects of two fluoride varnishes and a fluoride mouthrinse. Caries Res 1987;21:375-9. 16. Adriaens ML, Dermaut LR, Verbeeck RMH. The use of "Fluor Protector," a fluoride varnish, as a caries prevention method under orthodontic molar bands. Eur J Orthod 1990;12:316-9. 17. Boyd RL. Comparison of three self-applied topical fluoride preparations for control of decalcifications. Angle Orthod 1993;1:25-30. 18. Lobene R. A modified Gingival Index for use in clinical trials. Clin Prev Dent 1986;8:3-6. 19. Gibbs CH, Hirschfeld JW, Lee JG, Magnusson I, Thousand RR, Yerneni P, Clark WB. Description and clinical evaluation of a new computerized periodontal probe-the Florida Probe. J Clin Periodontoi 1988;15:137-44.

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20. Quigley GA, Hein JW. Comparative cleansing efl%iency of manual and power bmsifing. J Am Dent Assoc 1962;65:26-9. 21. Van der Weijden GA, Timmerman MF, Nijboer A, Lie MA, Van der Velden U. A comparative study of electrical toothbrushes for the effectiveness of plaque removal in relation to toothbrushing duration: timer study. J Clin Periodontol 1993;20:47681. 22. Walsh TW, Glenwright HD. Relative effectiveness of a rotary and conventional toothbrush in plaque removal. Commun Dent Oral Epidemiol 1984;12:160-4. 23. Baab DA, Johnson RH. The effect of a new electric toothbrush on supragingival plaque and gingivitis. J Periodontol 1989;60:336-41. 24. Van der Weijden GA, Danser MM, Nijboer A, Timmerman MF, Van der Velden U. The plaque removing efficacy of an oscillating/rotating toothbrush: a short-term study. J Clin Periodontol 1993;20:273-8. 25. Coontz ES. The effectiveness of a new oral hygiene device on plaque removal. Quintessence Int 1983;14(7):739-42. 26. van Venrooij JR, Philips C, Christensen J, Mayhew MJ. Plaque removal with a new powered instrument for orthodontic patients in fixed appliances. Compend Contin Educ Dent 1985;6:S142-6. 27. Long DE, Killoy WJ. Evaluation of the effectiveness of the Interplak home plaque removal instrument on plaque removal in orthodontic patients. Compend Contin Educ Dent I985;6:S156-60. 28. Martin WE, Kiger RD, Levy SM, Feller RP. A clinical evaluation of mechanical and conventional toothbrushing by institutionalized elderly patients. J Dent Res 1987;66:234. 29. Yankell SL, Emling RC, Cohen DW, Vanarsdall JR. A four-week evaluation of oral health in orthodontic patients using a new plaque-removal device. Compend Contin Educ Dent 1985;6:S123-7. 30. Killoy WJ, Love JW, Love J, Fed PF, Tira DE. The effectiveness of a counter-rotary action powered toothbrush and conventional toothbrush on plaque removal and gingival bleeding: a short term study. J Periodontol 1989;60:473-7. 31. Wilcoxon DB, Ackerman RJ, Killoy WJ, Love JW, Sakumura JS, Tira DE. The effectiveness of a counterrotational-aetion power toothbrush on plaque control in orthodontic patients. Am J Orthod Dentofac Orthop 1991;99:7-14. 32. Ciancio SG, Mather ML A clinical comparison of two electric toothbrushes with different mechanical actions. Clin Prey Dent 1990;i2(3):5-7. 33. Walsh TF, Glenwrigbt HD. Relative effectiveness of a rotary and conventional toothbrush in plaque removal. Commun Dent Oral EpidemioI 1984;12:160-4. 34. Glavind L, Zeuner E. The effectiveness of a rotary electric toothbrush on oral cleanliness in adults. J Clin Periodontol 1986;13:135-8. 35. Murray PA, Boyd RL, Robertson PB. Effect on periodontal status of rotary electric toothbrushes vs. manual toothbrushes during periodontal maintenance: II, microbiological results. J Periodontol 1989;60:396-401. 36. Boyd RL, Murray P, Robertson PB. Effect on periodontal status of rotary electric toothbrushes vs. manual toothbrushes during periodontal maintenance: I, clinical results. J Periodontol 1989;60:390-5. 37. Boyd RL, Murray P, Robertson PB. Effect of rotary electric toothbrush versus manual toothbrush on periodontal status during orthodontic treatment. Am J Orthod Dentofac Orthop 1989;96:342-7. 38. Jackson CL. Comparison between electrical toothb'rushing and manual toothbrushing, with and without oral irrigation, for oral hygiene of orthodontic patients. Am J Orthod Dentofac Orthop 1991;99:15-20. 39. Ash MM. A review of the problems and results of studies on manual and power toothbrushes. J Periodontol 1964;35:202-13.