Tooth Brushing Force Research Articles

Effect of toothbrush bristle stiffness and toothbrushing force on the abrasive dentine wear.

ObjectiveTo investigate the influence of toothbrush bristle stiffness and applied brushing force on the resulting abrasive dentine wear in vitro.MethodsOne hundred sixty bovine dentine samples were randomly allocated in eight groups (n = 20). Groups one to four were brushed with a soft‐bristle toothbrush with soft bristles applying 1, 2, 3 and 4 N brushing force, respectively. Groups five to eight were brushed with a medium‐bristle toothbrush applying the same aforementioned brushing forces (120 strokes/min, abrasive slurry (RDA = 121), 25 min). Profiles were recorded before and after the brushing sequence, and the median and interquartile range of abrasive dentine wear were calculated and compared using two‐way ANOVA and pairwise tests corrected after Tukey (α = 0.05).ResultsAt 1, 2 and 3 N brushing force, the tested toothbrushes caused no significantly different abrasive dentine wear. At 4 N brushing force, the medium‐bristle toothbrush caused statistically significantly higher abrasive force than the soft‐bristle toothbrush. Using the medium‐bristle toothbrush, abrasive dentine wear statistically significantly increased with increasing brushing force from 1 to 3 N. However, increasing the brushing force to 4 N did not result in statistically significantly higher wear. Using the soft‐bristle toothbrush, abrasive dentine wear statistically significantly increased with increasing brushing force from 1 to 2 N. However, increasing the brushing force to 3 or 4 N did not result in statistically significantly higher wear.ConclusionThe soft‐bristle toothbrush tends to cause less abrasive wear with increasing brushing force than the medium‐bristle toothbrush.

Gender difference of tooth brushing motion and force on self-brushing and caregivers' brushing in dental professionals

Gender difference of tooth brushing motion and force on self-brushing and caregivers' brushing in dental professionals

Effects of tooth-brushing force with a desensitising dentifrice on dentine tubule patency and surface roughness

ObjectivesTo investigate the effects of a 5% NovaMin containing dentifrice on dentine tubule patency and surface roughness at 100g and 400g tooth brush abrasion forces. Methods75 polished human dentine samples were prepared and randomly allocated into one of five groups; control (1), Na2PFO3 100g abrasion force (2), NovaMin 100g (3), Na2PFO3 400g (4) and NovaMin 400g (5). The control group underwent two 2-min cycles of artificial saliva (AS), one 2-min erosion cycle; the rest underwent two toothbrush abrasion cycles in an AS/dentifrice slurry and one 2-min erosion cycle. All samples were imaged at baseline and post intervention using Tandem Scanning Microscopy and Profilometry to analyse tubule patency and roughness. ResultsMean tubule patency increased significantly between baseline and post intervention in groups 1,2 and 4 and decreased significantly post intervention in groups 3 and 5 (p<0.01). Post intervention, there were statistically significant differences in mean patent tubules between NovaMin and the Na2PFO3 and control groups (p<0.001). Surface roughness increased for all groups between baseline and post interventions (P<0.001); mean (SD) roughness increases for groups 1, 2, 3, 4 and 5 were 0.14 (0.05) μm, 0.18 (0.04) μm, 0.16 (0.06) μm, 0.19 (0.07) μm and 0.21 (0.02) μm respectively. Differences between group 1 and 5 were significant (p<0.01). ConclusionsBrushing with NovaMin resulted in significant dentine tubule occlusion at 100g and 400g, but brushing with Na2PFO3 resulted in increased tubule patency. Surface roughness increased significantly at 400g brushing with NovaMin. There was no correlation between tubule patency and surface roughness. Clinical significanceA NovaMin desensitising dentifrice resulted in tubule occlusion even at high brushing forces. There was minimal increase in surface roughness at the lower (100g) brushing force.

Comparative evaluation of cemental abrasion caused by soft and medium bristle hardness toothbrushes at three predetermined toothbrushing forces: An in vitro study.

Background:Plaque control has been shown to have a pivotal role in maintaining optimal periodontal health. Toothbrushing as a mechanical plaque control tool is the most popular and effective option for self-performed oral health maintenance. However, the detrimental effects of bristle hardness and force exerted by toothbrushes on the tooth surface are the areas of concern.Objective:The aim of this in vitro study was to evaluate the abrasive effect of two different manual toothbrushes exerting predetermined forces on cemental surfaces of the teeth.Materials and Methods:Sixty extracted first molars were selected. Totally six experimental groups were formed based on the three predetermined forces 1.5, 3, and 4.5 Newton (N) and two types of manual toothbrushes, i.e., soft and medium bristle hardness. Buccal and lingual surfaces were independently brushed for 5000 cycles using specially designed toothbrushing machine. Throughout the experiment, type and quantity of toothpaste were kept constant. Post 5000 cycles of toothbrushing, change in surface roughness was measured using profilometer in microns and change in weight indicating loss of substance was measured in milligrams.Results:Abrasion of cementum is force dependent. Data revealed that both soft and medium bristle hardness toothbrushes cause significant cemental abrasion at 3 and 4.5 N forces.Conclusions:Higher is the force, more is the cemental surface abrasion. Soft bristled toothbrush causes more cemental abrasion than medium bristled toothbrush at 3 and 4.5 N forces.

1B27 歯ブラシの運動と力の3次元計測システムの開発

1B27 歯ブラシの運動と力の3次元計測システムの開発

The effect of toothbrush abrasion force on dentine hypersensitivity in-vitro

ObjectivesThis study investigated the effect of tooth brushing force on changes in dentine tubule patency in an erosion-toothbrush abrasion model. Methods60 dentine samples prepared with an artificial smear layer and divided randomly into control (no toothbrush), 100g, 200g or 400g toothbrush groups. They were immersed in 3:1 artificial saliva/NaF 1450ppm and either brushed (p35 soft tooth brush; 120 strokes) or not brushed. Then samples were subjected to agitated acid challenge (0.3% citric acid pH2.6 for 2min). Finally, samples were re-brushed. Calibrated software calculated patent dentine tubules that cause DH in confocal microscopy images taken of samples at each stage. ResultsAt baseline, mean patent tubules in all samples were 188 (SD54) with no significant inter-group differences. Following first brushing, mean patent tubules decreased using 100g to 150 (SD32) (p<0.01) and increased using 400g to 215 (SD45) (p=0.02). Following acid challenge, patent tubules increased to 218 (SD40) in all samples (p<0.01) with no significant inter-group differences. Following further brushing, mean patent tubules decreased using 100g to 175 (SD72) (p<0.01), but increased with 400g to 232 (SD52). ConclusionsAt higher brushing forces (400g), more tubules were exposed. At lower brushing forces (100g), tubule patency decreased even post-acidic challenge. Clinical significanceIt is often recommended to our patients with DH to brush using lighter brushing forces but our understanding of this force on dentine tubule patency is unknown. The management of DH requires lighter brushing forces to reduce the numbers of patent dentine tubules.

Analysis of tooth brushing cycles

The aim of this study was to demonstrate the effectiveness of an analysis of tooth brushing cycles using a system that measures tooth brushing motion and brushing force with an accelerometer and strain tension gage attached to a toothbrush. Mechanical plaque removal with a manual toothbrush remains the primary method of maintaining good oral hygiene for the majority of the population. Because toothbrush motion has not been fully understood, it should be clarified by analysis of tooth brushing cycles. Twenty healthy female dental hygienists participated in this study. Their tooth brushing motions were measured and analyzed using an American Dental Association-approved manual toothbrush to which a three-dimensional (3-D) accelerometer and strain tension gage were attached. 3-D motion and brushing force on the labial surface of the mandibular right central incisor and the lingual surface of the mandibular left first molar were measured, analyzed, and compared. Multilevel linear model analysis was applied to estimate variables and compare motion and forces related to the two tooth surfaces. The analysis of tooth brushing cycles was feasible, and significant differences were detected for durations and 3-D ranges of toothbrush motion as well as brushing force between the two tooth surfaces. The analysis used in this study demonstrated an ability to detect characteristics of tooth brushing motion, showing tooth brushing motion to change depending on the brushed location. These results also suggest that more detailed instructions might be required according to patient's oral condition.

Non‐carious cervical lesions and occlusion: a systematic review of clinical studies

Non-carious cervical lesions (NCCLs) are a group of lesions that affect the cervical area of the teeth. Different aetiological factors have been reported, among them tooth brushing force, erosive agents and occlusal forces. The aim of this study was to ascertain, by means of a systematic review, the association between NCCLs and occlusion. A search was performed in the MEDLINE database, retrieving a total of 286 articles. After title and abstract screening, the clinical investigations were read in full to select those that evaluated the occlusal aspects of NCCL aetiology. This systematic review describes the results of three prospective and 25 cross-sectional studies. As there is an extreme heterogeneity in design, diagnostic criteria, forms of analysis and associated factors, a meta-analysis was not possible. The wide variety of classification and diagnostic criteria reflects a high range of reported prevalence. An extensive heterogeneity of independent variables was noted, even in occlusal analysis, which helps to mask any conclusion about the role of occlusion in NCCL aetiology. The literature reveals that studies on this topic are subject to a substantial amount of bias, such as evaluation (use of non-blinded examiners) and confounding bias (no control of others aetiological factors). Up to now, it has been impossible to associate NCCLs with any specific causal agent, and the role of occlusion in the pathogenesis of non-carious cervical lesions seems as yet undetermined. Therefore, additional studies, properly designed to diminish bias, are warranted.

Does any relationship exist between self reported gingival bleeding, oral health perception, practices and concerns?

Background:The objective was to determine the relationship between self-reported gingival bleeding, oral health perception, practices and concerns.Materials and Methods:This cross-sectional survey among undergraduates of University of Benin, Benin City, Nigeria was conducted between April and May, 2011 using a self-administered 21-item structured questionnaire. Data analysis was done using Statistical Packages for the Social Sciences and P<0.05 was considered significant.Results:Out of the 400 questionnaires that were distributed, 338 were returned filled giving a retrieval rate of 84.5%. About three-quarters (71.3%) of the respondents were younger than 22 years. Males constituted 65.1% while the remaining 34.9% were females. The prevalence of self-reported gingival bleeding among respondents in this study was 12.7%. Individuals with gingival bleeding were significantly more likely to rate their dental and gingival health as fair/poor, use strong brushing stroke during tooth brushing and report worsening condition of teeth despite daily tooth brushing, express worry about the gingival color and less likely to be satisfied about the appearance of their teeth and to have received professional instruction on tooth brushing.Conclusion:Data from this survey revealed an established relationship between gingival bleeding, perceived dental and gingival health, tooth brushing force, professional instruction on tooth brushing, perception of the condition of teeth in relation to daily tooth brushing, worry about the color of gingiva, and satisfaction with the appearance of the teeth.

Does concern about halitosis influence individual′s oral hygiene practices?

Objective:The objective of this study was to assess whether the concern about halitosis influence oral health attitude and practices among young literate adults in Nigeria.Materials and Methods:This cross-sectional survey of 400 randomly selected temporary camp resident adults in Anambra state, South Eastern Nigeria was conducted using a modified version of the Hiroshima University-Dental Behavioral Inventory questionnaire.Results:Out of the 400 questionnaires distributed, only 294 were filled and returned giving an overall response rate of 73.5%. Half (50.0%) of the participants in this study expressed concern about halitosis. The participants that expressed concern about halitosis were mostly in the 25- to 27-year-old age group, females, known smoker, regular dental floss, and mouth wash users, had incorrect tooth brushing knowledge, brushed teeth more frequently and more forcefully, had no previous dental treatment, prefer symptomatic dental visit, experienced gingival bleeding, expressed worry about the color of their gingiva and teeth but were satisfied with the dental appearance.Conclusion:Data from this study showed that concerns about halitosis-triggered behavioral reaction in oral self-care practices namely tooth brushing frequency, tooth brushing force, mouth wash, and dental floss use. Also revealed were poorer oral health and lower preventive dental visit practices among participants concerned about halitosis. There is need for improved public knowledge and awareness about halitosis by the dentist in Nigeria.

Controlled Toothbrush Abrasion of Softened Human Enamel

The aim of this in vitro study was to compare toothbrush abrasion of softened enamel after brushing with two (soft and hard) toothbrushes. One hundred and fifty-six human enamel specimens were indented with a Knoop diamond. Salivary pellicle was formed in vitro over a period of 3 h. Erosive lesions were produced by means of 1% citric acid. A force-measuring device allowed a controlled toothbrushing force of 1.5 N. The specimens were brushed either in toothpaste slurry or with toothpaste in artificial saliva for 15 s. Enamel loss was calculated from the change in indentation depth of the same indent before and after abrasion. Mean surface losses (95% CI) were recorded in ten treatment groups: (1) soft toothbrush only [28 (17–39) nm]; (2) hard toothbrush only [25 (16–34) nm]; (3) soft toothbrush in Sensodyne MultiCare slurry [46 (27–65) nm]; (4) hard toothbrush in Sensodyne MultiCare slurry [45 (24–66) nm]; (5) soft toothbrush in Colgate sensation white slurry [71 (55–87) nm]; (6) hard toothbrush in Colgate sensation white slurry [85 (60–110) nm]; (7) soft toothbrush with Sensodyne MultiCare [48 (39–57) nm]; (8) hard toothbrush with Sensodyne MultiCare [40 (29–51) nm]; (9) soft toothbrush with Colgate sensation white [51 (37–65) nm]; (10) hard toothbrush with Colgate sensation white [52 (36–68) nm]. Neither soft nor hard toothbrushes produced significantly different toothbrush abrasion of softened human enamel in this model (p > 0.05).

The effect of duration and force of mechanical toothbrushing stimulation on proliferative activity of the junctional epithelium.

Gingival bleeding is frequently accompanied by an ulcerated epithelium, with repair depending on the proliferative activity of the epithelial cells. The present study examined the proliferative activity of the junctional epithelium (JE) under several different methods of toothbrushing stimulation. Twelve dogs were used in this 3-week experiment. Prior to the experiment, all teeth underwent daily removal of plaque and calculus using a scaler. Teeth were then divided into quadrants: 9 teeth in 3 quadrants (test, 3 per quadrant) were mechanically stimulated by toothbrushing for various time intervals (10, 20, or 40 seconds) and at various forces (100, 200, or 250 gf). The 3 teeth in the fourth quadrant served as controls. The proliferative activity of the basal cells of the junctional epithelium was evaluated for expression of proliferating cell nuclear antigen (PCNA). The numbers of PCNA-positive basal cells and total basal cells were counted, and the width of the junctional epithelium was measured. Toothbrushing force significantly affected the PCNA-positive basal cell ratio (P < 0.05). The 200 g toothbrushing force produced the highest PCNA-positive basal cell ratio, which was significantly higher than that using the 100 g force (P < 0.05). In junctional epithelium stimulated with a toothbrush, the PCNA-positive basal cell ratio is more sensitive to toothbrushing force than to duration.

Microstructural analysis of demineralized primary enamel after in vitro toothbrushing.

The aim of this study was to investigate, in vitro, the morphological characteristics of demineralized primary enamel subjected to brushing with a dentifrice with or without fluoride. In order to do so, 32 enamel blocks were divided in 4 different groups containing 8 blocks each. They were separately immersed in artificial saliva for 15 days. The experimental groups were: C - control; E - submitted to etching with 37% phosphoric acid gel (30 s); EB - submitted to etching and brushing 3 times a day with a non-fluoridated dentifrice; EBF = submitted to etching and brushing 3 times a day with a fluoridated dentifrice. The toothbrushing force was standardized at 0.2 kgf and 15 double strokes were performed on each block. After the experimental period, the samples were prepared and examined under SEM. The control group (C) showed a smooth surface, presenting scratches caused by habitual toothbrushing. The etched samples (E) exhibited different degrees of surface disintegration, but the pattern of acid etching was predominantly the type II dissolution. The brushed surfaces were smooth, with elevations which corresponded to the exposure of Tomes' process pits and depressions which corresponded to interrod enamel. Particles resembling calcium carbonate were found in the most protected parts of the grooves. No morphological differences were observed between brushing with fluoridated (EBF) and non-fluoridated (EB) dentifrice. The results suggest that the mechanical abrasion caused by brushing demineralized enamel with dentifrice smoothes the rough etched surface, and the presence of fluoride does not cause morphological modifications in this pattern.

Toothbrushing forces in children with fixed orthodontic appliances.

The aim of this investigation was to determine whether toothbrushing forces are influenced by wearing fixed orthodontic appliances. Thirty children, (10 males, 20 females) with planned fixed appliance therapy and aged 10-15 years, were recruited to the study. No subject had previously worn an orthodontic appliance. At baseline, each subject brushed their teeth in their usual way, unsupervised. The toothbrush used was a purpose-designed electronic instrument that measured the force applied to the brush and transmitted force data by radio to a remote PC. After toothbrushing, subjects had orthodontic brackets fitted. Toothbrushing was repeated at 2 and 14 weeks after baseline, and brushing forces recorded. There were no significant differences between the measurements made at baseline and those made at 2 and 14 weeks. There were no differences between males and females in the forces used at any time point. It was concluded that toothbrushing forces are unaffected by placing fixed orthodontic appliances in children. The brushing forces recorded were comparable with those previously found by other investigators.

Relationship between the plaque removal efficacy of a manual toothbrush and brushing force.

This survey investigated the association between the efficacy of plaque removal and toothbrushing forces during a normal brushing regime. The 94 subjects participating in this study were requested not to brush 24 h prior to the experiment. Panelists brushed for 1 min with a manual toothbrush. Before and after brushing, plaque was assessed using the Turesky modification of the Quigley & Hein plaque index. A second 1-min exercise of brushing was carried out to assess the toothbrushing force. The mean plaque reduction was 39%, with vestibular surfaces being cleaned most effective (69%) and the lingual surfaces the least (21%). The mean brushing force was 330 g. No correlation was observed between efficacy and brushing force (r=0.14, p=0.16). The relationship between pre- and post-brushing plaque was stronger (r=0.68, p<0.001). Multiple regression analysis entering squared values of force as an independent variable into the equation, indicated that the relation between efficacy and force was not linear. A curve could be fitted to the plot (p=0.0004), demonstrating that up to a certain level of force, an increase of force is associated with an increase in efficacy (r=0.33, p<0.01). Beyond this point, application of higher forces resulted in reduced efficacy (r=-0.49, p=0.03). As was calculated in this particular test this 'transition' level of force was 407.4 g. The absence of a correlation between brushing force and plaque removal efficacy suggests that in a 'user model' brushing situation, other factors than brushing force are of major influence on the amount of plaque removed.

Toothbrush pressures of orthodontic patients

The intention of this study was to determine whether toothbrushing pressures varied significantly between groups of orthodontic patients who were good toothbrushers and those who were poor toothbrushers. Seventy-two patients undergoing full-banded orthodontic treatment were selected from the author's practice and were subjectively paired by him according to their habitual oral hygiene. One group of thirty-six patients who habitually displayed poor oral hygiene was compared to a group of thirty-six patients who habitually displayed good oral hygiene. A specially designed strain gauge with a force-averaging feedback mechanism was attached to each patient's manual toothbrush, and the force with which that patient brushed was averaged and recorded in pounds. The poor brushers averaged 0.20 pound, whereas the average pressure of the good brushers was 0.89 pound. The statistical evidence indicates that the difference between the two groups is highly significant and is unlikely to be due to chance alone. This study has shown that toothbrush pressures can be easily and accurately measured. The attempt to objectify a single characteristic of toothbrushing behavior in an orthodontic population is an effort to avoid the medical model explanation of behavior vis-a-vis the nonspecific and subjective word attitude. Future studies will determine whether poor toothbrushers can be changed into good toothbrushers through the progressive acquisition of greater toothbrushing forces.

Abrasive wear of bonding adhesives: Studies during treatment and after bracket removal

Two clinical experiments were performed to evaluate the rate of abrasive wear of some commonly used bonding materials, all filled diacrylate resins. The first study was done on seven orthodontic patients. When the four maxillary incisors were bonded, excess material was deliberately left around the margin of the bracket bases. Bonding adhesives with submicron-size (0.2 to 0.3 μm) filler particles (adhesive E) and larger (average 10 to 30 μm), coarser fillers (adhesives C and S) were studied. The three adhesives were randomly divided between the patients, so that any two of them were used in the same person. At time of bonding and 3 and 6 months later, impressions of the incisors were taken and positive replicas were made. Stereomicroscopy and scanning electron microscopy were used to evaluate any reduction and/or differences in appearance of excess adhesive. The second experiment took place after debonding in ten other persons. At the time of bracket removal, residual adhesive was purposely left on those teeth expected to be most exposed to tooth-brushing forces, namely, the maxillary left canines and neighboring teeth. Studies on abrasive wear in this part were restricted to the adhesive with submicron-size filler particles. A quick-etch technique (10 seconds) proved efficient in revealing the remnants and their wear pattern. The teeth were examined for presence and appearance of residual adhesive at 1- to 2-month intervals for a period of up to 1 year. Standardized intraoral photographs were taken at each visit. Both experiments demonstrated uniform and somewhat surprising results in that the abrasion of all three bonding materials apparently was minimal. Around brackets (Experiment I), excess of the adhesive with submicron filler particles demonstrated slightly more smoothening of surface irregularities than that of the two adhesives with larger filler particles. The latter remained practically unchanged throughout the periods observed. After debonding (Experiment II), the residual adhesive with submicron filler particles showed clinically almost insignificant abrasion. Only the very thin films of adhesive were reduced in size or eliminated, while the thicker layers showed almost no wear over the 1-year observation period (Figs. 6 to 8). As discussed, the clinical consequence of minimal abrasive wear should be that great emphasis must be paid to the use of (1) a bonding technique focused on active removal of excess adhesive around the bracket bases and (2) a debonding technique in which the enamel is left virtually free of adhesive remnants.

Wear of the toothbrush bristles under Bass technique with special reference to the toothbrushing force (author's transl)

The present study was made in vivo and weekly observed to the wear of toothbrush bristles under Bass technique reference to the toothbrushing force, and also to the pollution of the toothbrush bristles.The results obtained were as follows:1. Toothbrushing force in Bass technique was 218g on average.2. Discrepancy in the individual tooth brushing patterns which were evident from the brushing force curve was due to the individual variation in relation to grasp of the toothbrush.3. At one week after brushing, the wear of the toothbrush bristles were a little regardless of the toothbrushing forces. At four weeks after brushing, the tip of bristles was observed to overspread above average of the brushing force.4. At one week after brushing, coccoid microorganisms were observed at the round cut off tip of the bristles. Thereafter, coccoid and rod-like microorganisms were observed around the tip of the bristles.

Toothbrushing force, the number of brushing strokes and plaque removal effect with manual toothbrushes with reference to the number of times a toothbrush is used

Toothbrushing force, the number of brushing strokes and plaque removal effect with manual toothbrushes with reference to the number of times a toothbrush is used

EFFECTS OF TOOTHBRUSHING HABITS AND TOOTHBRUSHING FORCE ON TOOTHBRUSHING

Toothbrushing habits were studied by chronocyclograph and EMG as to the movements o upper extremity muscles. Quantitative determinations were successfully made of toothbrushing force and contact pressure of toothbrush against the teeth.In a toothbrushing with a manual toothbrush horizontally or with a stiff bristle manual toothbrush, M. deltoideus got markedly contracted. The rolling toothbrushing method or the use of a soft bristle manual brush was accompanied by active exertion of M. flexor carpi radialis and M. flexor pollicis brevis.Toothbrushing force changes depending upon the kind of the brush used and the locality of brushing as well as upon the stiffness or softness of bristle. It is even more influenced by individual brushing activities, that is habits in brushing.Individuality of toothbrushing force was more marked with a manual toothbrush than with an automatic toothbrush. Individuality of contact pressure was also found with a manual toothbrush.1) Contact pressure was generally 20-400g, and toothbrushing force 200-1000g, proportional relationship being not always existent between the former and the latter.2) Toothbrushing force with a manual soft bristle toothbrush was greater than with a manual stiff bristle toothbrush.3) Toothbrushing force with the same manual toothbrush showed no variation subject to different toothbrushing methods.4) Toothbrushing force with a manual toothbrush on a rolling method showed variations depending upon the locality of toothbrushing, i. e., toothbrushing force was greater in anterior teeth than in lateral teeth. But no variations were observed on a horizontal method.5) Toothbrushing force was greater in the frontal bristle portion of a manual toothbrush than in the middle or the rear portion.6) Toothbrushing force with an automatic toothbrush revealed slightly less individuality than with a manual toothbrush. But no relationship in toothbrushing force was observed between these two toothbrushes.When a manual toothbrush was used a corelationship was observed between toothbrushing force and effectiveness of toothbrushing with Skinner's iodine solution, i. e., the greater the toothbrushing force the more the effectiveness of toothbrushing. Thus it is required that individuals, who perfunctly brush their teeth improve their habitual practice of brushing.An automatic toothbrushing was not so much affected by toothbrushing habits as a manual toothbrushing. It's effectiveness, being various, was not related with toothbrushing force.But an automatic toothbrushing, if performed with purposely varying toothbrushing force. might show more effectiveness as toothbrushing force increased.In order to use an automatic toothbrush most effectively attention should be given to toothbrushing force or to the prolongation of brushing time. It is suggested that an automatic toothbrush be equipped with an apparatus to adjust toothbrushing force with care that too big toothbrushing force may influence upon periodontal tissues.