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Cleansing effectiveness of conventional and electric toothbrushes
Cleansing effectiveness of conventional and electric toothbrushes: a clinical comparison
John C. Derbyshire,* D.D.S., M.S., Upper Darby, Pa., and Surendra M. Mankodi,f B.D.S., M.S.D., Iowa City
When manual and electric toothbrushes were compared, the electric toothbrush was found superior in overall cleansing effectiveness. It is significant that the subjects for the study were students of dental hygiene who could be expected to be more conscientious and skillful man ual brushers than members of the general population.
The accepted instrument for use in oral hygiene is the toothbrush, and recently the electrically powered toothbrush has become available. Both the public and the dental profession first regarded it as merely a gadget; however, some have suggested that it has psychological appeal and that people enjoy using it, brush longer with it and thereby improve their oral hygiene.1 Were this its only value, the advantages which accrue when it
is used probably would be short-lived. The purpose of this study was to find whether there was any physical benefit to be gained from use of the electric brush or whether all the reported advantage stemmed from its gadget appeal. In another study2 we had compared the conventional toothbrush with an elec trically powered toothbrush3 (Broxodent, E. R. Squibb and Sons Co.) with regard to the stimulation of gingival keratinization. When stained by the Papanicolaou technic, gingival smears taken from quadrants brushed with the electric brush were found to have more kerati nized cells than smears from the manu ally brushed quadrants. Periodontal patients or handicapped children used as subjects in many other studies of this new method of toothbrushing probably would benefit from the rou tine use of any toothbrush. We believe that comparisons of brushing methods
64/313 • THE JO U R N A L OF THE A M E R IC A N DENTAL A SSO C IA TIO N
Sample o f p a rt o f c h a rt used fo r scoring stains on tee th. Top circles represent m axillary te e th ; bottom ones, m a n d ib u la r te e th . Numerals designate po sitio n o f tee th in mouth. Bold horizontal line through circles divides them in to buccal surface on outside and lingual or p a la tal surface on inside. Smaller lines inside circle d iv id e it into various segments, such as, mesial, centra) and dista l. Thick black marks are regions o f stain. Thus, to o th no. 18 w ill have maximum score o f 6; no. 19 has score o f 5, and no. 21 has score o f I
made with such groups do not constitute a rigorous enough test for the electrically powered toothbrush. The subjects in this study were female students of dental hygiene plus two fe male dental hygiene instructors at the State University of Iowa College of Den tistry. There were 29 subjects in the study, and the group was of uniform age, 20 to 27 years. Being students of dental hygiene, they were thought the best mo tivated and trained group of manual brushers available. Because of their train ing, they also were more apt to follow a standardized and thorough technic of manual brushing. Furthermore, all had complete dentitions except for a few with out first bicuspids, which had been ex tracted for orthodontic reasons, and a few without third molars, which either had been extracted or had not erupted. Neither periodontal involvement nor mal occlusion of any consequence was found in any subject. The mean number of brushings per day was 3.38 times. During the study, all subjects used the same brand of dentifrice, the same type of manual toothbrush (2-row, hard bristle) and the same type o f electrically powered toothbrush (Broxodent). M ETHOD
Initially, all subjects were given a prophy laxis, the thoroughness of which was assured by the use of the disclosing solu tion. Each participant was instructed to
brush one side of her mouth, upper and lower, with the conventional brush, and the other side with the electric brush. After three weeks of this regimen the subjects were examined in the following manner: After thorough rinsing of the mouth with the disclosing solution, plaque accumulations were charted and scored. One of us (S.M .M .), who did not know which side had been brushed with the electric brush, evaluated the sub jects’ mouths for cleanliness. A six-pointsper-tooth scale was designed tp score the six clearly defined regions of a tooth: mesiobuccal, buccal central, distobuccal, mesiolingual, lingual central and distolingual surfaces (illustration). In this scoring method, the occlusal surface is not taken into account. The presence of stain in any amount of any one of the six tooth surfaces was counted as a score of one. Thus, the score for a single tooth can vary from a minimum of zero to a maximum of six. This was desig nated as the “ raw” score. Because the anterior teeth constituted a region of overlap between the two brushing meth ods, only the molars and bicuspids in each quadrant were scored for plaque accumu lation. This completed the measurements in the first or A series, after which the sub jects used the manual brush only for four weeks. This four-week interval was in tended to negate the effects of the electric brush. At the end of this period, another thorough prophylaxis was given, and the
DERBYSHIRE— M A N K O D I . . . VOLUME 69, SEPTEMBER 1964 • 65/319
subjects started a second three-week pro gram (series B) in which they reversed the sides on which the two brushes were used in series A. At the conclusion of the trial, the subjects were examined as in series A, and the plaque scoring was re peated.
Table • Comparison of cleanliness electric and manual toothbrushing
Method of brushing
Mean of plaque scores (%) Upper arch
low er arch
achieved
by
Standard deviation Upper arch
Lower arch
Electric
25.13
46.66
13.42
16.20
Manual
33.93
51.00
17.13
17.72
O B S E R V A T IO N S
To remove any effect of left- or righthandedness in this study, plaque scores from all quadrants brushed with the elec tric brush, in both series A and B, were totaled without regard to the side of the mouth brushed. Similarly, all manually brushed quadrants in both series A and B were totaled regardless of side of the mouth brushed. This procedure provided us with four columns of plaque scores, one for each of the following: electric upper, electric lower, manual upper and manual lower quadrants. T o correct for the num ber of missing teeth in the quadrants under examination, plaque raw scores were converted to percentage scores. Per centage scores are arrived at by multiply ing the sum of individual scores of teeth in the quadrant by the factor of 100 over maximum possible score in the same quadrant. Calculation of the mean and standard deviation of each of these col umns indicated that a difference in mean cleanliness did exist between upper and lower or between manual and electric brushing methods (table). The most effective cleaning was in the upper arch with the electric brush. Fol lowing this combination in order of ef fectiveness were the upper arch-manual brush, lower arch-electric brush and lower arch-manual brush combinations. There fore, it was necessary to find whether this mean difference in cleaning effective ness was attributable to the arch, to the brushing method or to an interaction be tween arch and brushing method. The statistical technic used to test the signifi cance of our results was the analysis of variance. The specific test employed was the two-factor, repeated measurement de-
sign as advocated by Lindquist.3 The level of significance chosen was 0.01. The value of F at this level was 7.6. The initial step was to evaluate the arches, upper against lower, without re gard to brushing method. The obtained F value of 63.98 is far greater than that required for significance at the 0.01 level. It indicated that the upper arch was more thoroughly cleaned than the lower in this group of better than average brushers. Because this test showed a significant dif ference in cleanliness favoring the upper arch, the test of the interaction of the' method of brushing and the arch was set up. We wished to know whether the su perior cleanliness in the upper arch was due to a particular brushing method. The mean difference proved to be nonsignifi cant at the 0.01 level, the obtained F value being 1.28. Thus, it can be con cluded that the mean difference in clean liness between upper and lower arches was not attributable to a method of brush ing but rather to the inherent ease with which the upper arch can be cleaned. Because the superior degree of cleanli ness of the upper arch could not be at tributed to particular brushing technic, the difference in overall cleanliness was compared as to brushing method regard less of arch. In other words, all quadrants brushed with the electric brush were com pared to all manually brushed quadrants. The obtained F value of 14.06 in this instance proved greater than the F value required to show significance at the 0.01 level of confidence. Therefore, when the mean difference in overall cleansing effec
¿6/320 • THE JO U R N A L OF THE A M E R IC A N DENTAL A SSO C IA T IO N
tiveness between the two brushing meth ods is considered, this difference is signifi cant and attributable to the electric brush. SUM M ARY
A comparison of a manually operated toothbrush and an electrically powered toothbrush (Broxodent) was undertaken. A select sample of well-trained, highly motivated students of dental hygiene was used as subjects. A comparison of the cleansing effectiveness was made. The following conclusions were reached: In this select group, the upper arch was cleaned more effectively than the lower arch. The superior cleanliness of the upper arch was attributable to the inherent ease with which the upper arch can be cleaned by either brushing technic. The electrically powered brush used in this study was superior in overall cleaning effectiveness to the manually operated brush. We believe that the subjects in this study provided a rigorous test for
comparison of the electrically powered toothbrush with the manually operated toothbrush. That it was proved superior to the manual brush when used by this select group of subjects emphasizes its po tential value for the general population. This potential can be realized by devel oping a systematic brushing technic, the effectiveness of which can be evaluated by the use of disclosing solution. 323 Sherbrook Boulevard
The authors thank Dr. Dee Norton, College of Educa tion, State University of Iowa, for his assistance and advice regarding the statistical analysis of the data, and the E. R. Squibb and Sons Co. for their support of this study. *Assistant professor of stomatology, State University of Iowa, College of Dentistry, Iowa City. Currently USPHS postdoctoral research fellow, University of Penn sylvania, School of Dental Medicine. tVisiting assistant professor of stomatology, State University of Iowa, College of Dentistry. 1. Quigley, Gertrude A., and Hein, B. W. Compara tive cleansing efficiency of manual and power brushing. JADA 65:26 July 1962. 2. Derbyshire, John C., and Mankodi, Surendra M. Gingival keratinization with conventional and electric toothbrushes: a cytological comparison. JADA *68:255 Feb. 1964. 3. Lindquist, E. F. Design and analysis of experiments in psychology and education. Boston, Houghton Mifflin Co., 1953, p. 393.
Problems of In ner Space • W e d o better w ith the p ro b le m s o f O u t e r S p a c e t h a n w e d o w ith the p ro b le m s o f In n e r S p a c e — th a t is, w h a t is c o n ta in e d w it h in o u r o w n selves a n d o u r p a tte rn s o f b e h a vio r. N o less a th in k e r th a n B e r t ra n d R u s s e ll h as said th a t the scie ntists m u s t close this g a p o r else “ M a n w ill d e stro y h im se lf w ith h is h a lfw a y cleverness.” Frank Stanton, Stanford
University M ed ical C enter Dedication Cerem ony, S eptem ber 18, 1959.
John C. Derbyshire,* D.D.S., M.S., Upper Darby, Pa., and Surendra M. Mankodi,f B.D.S., M.S.D., Iowa City
When manual and electric toothbrushes were compared, the electric toothbrush was found superior in overall cleansing effectiveness. It is significant that the subjects for the study were students of dental hygiene who could be expected to be more conscientious and skillful man ual brushers than members of the general population.
The accepted instrument for use in oral hygiene is the toothbrush, and recently the electrically powered toothbrush has become available. Both the public and the dental profession first regarded it as merely a gadget; however, some have suggested that it has psychological appeal and that people enjoy using it, brush longer with it and thereby improve their oral hygiene.1 Were this its only value, the advantages which accrue when it
is used probably would be short-lived. The purpose of this study was to find whether there was any physical benefit to be gained from use of the electric brush or whether all the reported advantage stemmed from its gadget appeal. In another study2 we had compared the conventional toothbrush with an elec trically powered toothbrush3 (Broxodent, E. R. Squibb and Sons Co.) with regard to the stimulation of gingival keratinization. When stained by the Papanicolaou technic, gingival smears taken from quadrants brushed with the electric brush were found to have more kerati nized cells than smears from the manu ally brushed quadrants. Periodontal patients or handicapped children used as subjects in many other studies of this new method of toothbrushing probably would benefit from the rou tine use of any toothbrush. We believe that comparisons of brushing methods
64/313 • THE JO U R N A L OF THE A M E R IC A N DENTAL A SSO C IA TIO N
Sample o f p a rt o f c h a rt used fo r scoring stains on tee th. Top circles represent m axillary te e th ; bottom ones, m a n d ib u la r te e th . Numerals designate po sitio n o f tee th in mouth. Bold horizontal line through circles divides them in to buccal surface on outside and lingual or p a la tal surface on inside. Smaller lines inside circle d iv id e it into various segments, such as, mesial, centra) and dista l. Thick black marks are regions o f stain. Thus, to o th no. 18 w ill have maximum score o f 6; no. 19 has score o f 5, and no. 21 has score o f I
made with such groups do not constitute a rigorous enough test for the electrically powered toothbrush. The subjects in this study were female students of dental hygiene plus two fe male dental hygiene instructors at the State University of Iowa College of Den tistry. There were 29 subjects in the study, and the group was of uniform age, 20 to 27 years. Being students of dental hygiene, they were thought the best mo tivated and trained group of manual brushers available. Because of their train ing, they also were more apt to follow a standardized and thorough technic of manual brushing. Furthermore, all had complete dentitions except for a few with out first bicuspids, which had been ex tracted for orthodontic reasons, and a few without third molars, which either had been extracted or had not erupted. Neither periodontal involvement nor mal occlusion of any consequence was found in any subject. The mean number of brushings per day was 3.38 times. During the study, all subjects used the same brand of dentifrice, the same type of manual toothbrush (2-row, hard bristle) and the same type o f electrically powered toothbrush (Broxodent). M ETHOD
Initially, all subjects were given a prophy laxis, the thoroughness of which was assured by the use of the disclosing solu tion. Each participant was instructed to
brush one side of her mouth, upper and lower, with the conventional brush, and the other side with the electric brush. After three weeks of this regimen the subjects were examined in the following manner: After thorough rinsing of the mouth with the disclosing solution, plaque accumulations were charted and scored. One of us (S.M .M .), who did not know which side had been brushed with the electric brush, evaluated the sub jects’ mouths for cleanliness. A six-pointsper-tooth scale was designed tp score the six clearly defined regions of a tooth: mesiobuccal, buccal central, distobuccal, mesiolingual, lingual central and distolingual surfaces (illustration). In this scoring method, the occlusal surface is not taken into account. The presence of stain in any amount of any one of the six tooth surfaces was counted as a score of one. Thus, the score for a single tooth can vary from a minimum of zero to a maximum of six. This was desig nated as the “ raw” score. Because the anterior teeth constituted a region of overlap between the two brushing meth ods, only the molars and bicuspids in each quadrant were scored for plaque accumu lation. This completed the measurements in the first or A series, after which the sub jects used the manual brush only for four weeks. This four-week interval was in tended to negate the effects of the electric brush. At the end of this period, another thorough prophylaxis was given, and the
DERBYSHIRE— M A N K O D I . . . VOLUME 69, SEPTEMBER 1964 • 65/319
subjects started a second three-week pro gram (series B) in which they reversed the sides on which the two brushes were used in series A. At the conclusion of the trial, the subjects were examined as in series A, and the plaque scoring was re peated.
Table • Comparison of cleanliness electric and manual toothbrushing
Method of brushing
Mean of plaque scores (%) Upper arch
low er arch
achieved
by
Standard deviation Upper arch
Lower arch
Electric
25.13
46.66
13.42
16.20
Manual
33.93
51.00
17.13
17.72
O B S E R V A T IO N S
To remove any effect of left- or righthandedness in this study, plaque scores from all quadrants brushed with the elec tric brush, in both series A and B, were totaled without regard to the side of the mouth brushed. Similarly, all manually brushed quadrants in both series A and B were totaled regardless of side of the mouth brushed. This procedure provided us with four columns of plaque scores, one for each of the following: electric upper, electric lower, manual upper and manual lower quadrants. T o correct for the num ber of missing teeth in the quadrants under examination, plaque raw scores were converted to percentage scores. Per centage scores are arrived at by multiply ing the sum of individual scores of teeth in the quadrant by the factor of 100 over maximum possible score in the same quadrant. Calculation of the mean and standard deviation of each of these col umns indicated that a difference in mean cleanliness did exist between upper and lower or between manual and electric brushing methods (table). The most effective cleaning was in the upper arch with the electric brush. Fol lowing this combination in order of ef fectiveness were the upper arch-manual brush, lower arch-electric brush and lower arch-manual brush combinations. There fore, it was necessary to find whether this mean difference in cleaning effective ness was attributable to the arch, to the brushing method or to an interaction be tween arch and brushing method. The statistical technic used to test the signifi cance of our results was the analysis of variance. The specific test employed was the two-factor, repeated measurement de-
sign as advocated by Lindquist.3 The level of significance chosen was 0.01. The value of F at this level was 7.6. The initial step was to evaluate the arches, upper against lower, without re gard to brushing method. The obtained F value of 63.98 is far greater than that required for significance at the 0.01 level. It indicated that the upper arch was more thoroughly cleaned than the lower in this group of better than average brushers. Because this test showed a significant dif ference in cleanliness favoring the upper arch, the test of the interaction of the' method of brushing and the arch was set up. We wished to know whether the su perior cleanliness in the upper arch was due to a particular brushing method. The mean difference proved to be nonsignifi cant at the 0.01 level, the obtained F value being 1.28. Thus, it can be con cluded that the mean difference in clean liness between upper and lower arches was not attributable to a method of brush ing but rather to the inherent ease with which the upper arch can be cleaned. Because the superior degree of cleanli ness of the upper arch could not be at tributed to particular brushing technic, the difference in overall cleanliness was compared as to brushing method regard less of arch. In other words, all quadrants brushed with the electric brush were com pared to all manually brushed quadrants. The obtained F value of 14.06 in this instance proved greater than the F value required to show significance at the 0.01 level of confidence. Therefore, when the mean difference in overall cleansing effec
¿6/320 • THE JO U R N A L OF THE A M E R IC A N DENTAL A SSO C IA T IO N
tiveness between the two brushing meth ods is considered, this difference is signifi cant and attributable to the electric brush. SUM M ARY
A comparison of a manually operated toothbrush and an electrically powered toothbrush (Broxodent) was undertaken. A select sample of well-trained, highly motivated students of dental hygiene was used as subjects. A comparison of the cleansing effectiveness was made. The following conclusions were reached: In this select group, the upper arch was cleaned more effectively than the lower arch. The superior cleanliness of the upper arch was attributable to the inherent ease with which the upper arch can be cleaned by either brushing technic. The electrically powered brush used in this study was superior in overall cleaning effectiveness to the manually operated brush. We believe that the subjects in this study provided a rigorous test for
comparison of the electrically powered toothbrush with the manually operated toothbrush. That it was proved superior to the manual brush when used by this select group of subjects emphasizes its po tential value for the general population. This potential can be realized by devel oping a systematic brushing technic, the effectiveness of which can be evaluated by the use of disclosing solution. 323 Sherbrook Boulevard
The authors thank Dr. Dee Norton, College of Educa tion, State University of Iowa, for his assistance and advice regarding the statistical analysis of the data, and the E. R. Squibb and Sons Co. for their support of this study. *Assistant professor of stomatology, State University of Iowa, College of Dentistry, Iowa City. Currently USPHS postdoctoral research fellow, University of Penn sylvania, School of Dental Medicine. tVisiting assistant professor of stomatology, State University of Iowa, College of Dentistry. 1. Quigley, Gertrude A., and Hein, B. W. Compara tive cleansing efficiency of manual and power brushing. JADA 65:26 July 1962. 2. Derbyshire, John C., and Mankodi, Surendra M. Gingival keratinization with conventional and electric toothbrushes: a cytological comparison. JADA *68:255 Feb. 1964. 3. Lindquist, E. F. Design and analysis of experiments in psychology and education. Boston, Houghton Mifflin Co., 1953, p. 393.
Problems of In ner Space • W e d o better w ith the p ro b le m s o f O u t e r S p a c e t h a n w e d o w ith the p ro b le m s o f In n e r S p a c e — th a t is, w h a t is c o n ta in e d w it h in o u r o w n selves a n d o u r p a tte rn s o f b e h a vio r. N o less a th in k e r th a n B e r t ra n d R u s s e ll h as said th a t the scie ntists m u s t close this g a p o r else “ M a n w ill d e stro y h im se lf w ith h is h a lfw a y cleverness.” Frank Stanton, Stanford
University M ed ical C enter Dedication Cerem ony, S eptem ber 18, 1959.