Toothbrushing force in relation to plaque removal

Plaque removal characteristics of electric toothbrushes using an in vitro plaque model

BACKGROUND/AIM

The purpose of the study was to investigate and quantify the efficacy of plaque removal by commercially available electric toothbrushes using an in vitro system based on artificial plaque grown on glass slides.

MATERIAL AND METHODS

Artificial plaque based on Streptococcus sanguis and Streptococcus mutans was cultured in a series of phosphate buffer solution, sucrose solution and brain heart infusion on sterile glass slides, for a period of 5 weeks. 7 different electric toothbrushes of current designs were operated in contact with the glass slides under loads of 1 or 2N for 10 s after which image analysis of the brushed slides was undertaken to calculate the absolute and relative areas of removal.

RESULTS

The electric toothbrushes showed a larger area of plaque removal as loading force increased from 1 to 2N. The area of biofilm removed also depended on the head design and ranged from 258 mm(2) (1N, Interplak) and 314 mm(2) (2N, Interplak), to 30 mm(2) (1N, Braun 3D), and 148 mm(2) (2N, Blend-a-Dent). The area of biofilm removal was significantly different among all electric toothbrushes at p<0.01 (ANOVA). All electric toothbrushes removed more biofilm than the actual contacting tufted area of the head.

CONCLUSION

The artificial plaque model system under different loading conditions showed differences in the absolute area of removal per electric toothbrush and also differences in the relative removal per unit contact bristle area. These differences on operating variables should be considered when evaluating new electric toothbrushes.

Comparison of the clinical effects and gingival abrasion aspects of manual and electric toothbrushes

AIMS

The clinical effects and gingival abrasion aspects of 2 electrical tooth-brushes (Braun Oral-B Plak Control Ultra and the novel development Braun Oral-B Plak Control 3D) were to be compared with conventional manual tooth-brushing.

MATERIAL AND METHODS

In a cross-over study, 26 dental student volunteers participated and were assigned to 1 of 3 groups. Following instruction in the use of the electric as well as manual toothbrushes, the volunteers were timed for 2 min each day to apply one electric or the manual toothbrush, respectively, during 3 experimental phases of 2 weeks. No other methods of tooth cleaning were to be performed except the one specified for the respective test period. When brushing manually, the Bass toothbrushing technique was applied. Between each test period, a recovery period of 1 week was allowed during which no oral hygiene was performed at all. At the start and the end of each of the experimental periods, the extension of plaque deposits from the gingival margin in coronal direction was assessed using the Turesky et al. modification of the Quigley and Hein plaque index. Presence or absence of gingival inflammation was evaluated by bleeding and probing (BOP). The extent and severity of gingival abrasions were assessed by use of a modified method of Breitenmoser et al. and adapted by Danser et al.

RESULTS

The plaque-reducing effect was similar in all groups with the same cleaning regime. For that reason, the result of the different experimental phases with the respective cleaning modalities were collapsed. Cleaning with the Braun Oral-B Plak Control Ultra electric toothbrush resulted consistently in the lowest plaque scores when compared to both the Braun Oral-B Plak Control 3D and the manual toothbrush. Although the differences in plaque reduction were statistically significant between cleaning with Braun Oral-B Plak Control Ultra and 3D, they were small and of questionable clinical relevance. No significant differences in plaque reductions were found between manual brushing and any of the 2 electric brushes. Gingival abrasions were least pronounced following brushing with the Braun Oral-B Plak Control 3D electric toothbrush. However, no significant differences in gingival abrasion were encountered following brushing with the Braun Oral-B Plak Control Ultra electric in comparison with the manual toothbrush.

CONCLUSIONS

The results of the present study have shown that in a group of dental students trained in manual brushing technique, where efficacy was similar with the 3 toothbrushes tested, there is no evidence of greater gingival abrasion with either Braun Oral-B Plak Control Ultra or 3D when compared with a manual brush.

Effect of brushing with sonic and counterrotational toothbrushes on the bond strength of full veneer crowns

STATEMENT OF PROBLEM

Earlier studies on orthodontic brackets have shown a loss of bond strength after a sonic toothbrush was used.

PURPOSE

This in vitro study evaluated the difference in bond strength of single complete veneer crowns after being subjected to the equivalent of 2 years of brushing with sonic and counterrotational toothbrushes.

MATERIAL AND METHODS

Complete gold crowns were fabricated with a conventional indirect technique for 30 extracted, intact, prepared human premolar teeth. Castings were then luted to the teeth with glass ionomer cement. Teeth were randomly divided into 3 groups of 10 teeth each, 1 group to be brushed with Sonicare sonic toothbrush, 1 group to be brushed with Interplak counterrotational mechanical toothbrush, and 1 group as the control. Groups 1 and 2 were then brushed for the equivalent of 2 years per tooth. A uniform force of 50 g for the sonic toothbrush and 120 g for the counterrotational toothbrush was used. Control specimens were not brushed. Brush heads and sample teeth in contact with the toothbrush were kept moist at all times. Tensile dislodgment force was determined with an Instron universal testing machine.

RESULTS

The castings brushed with a sonic toothbrush required a mean of 43.22 kg (+/- 11.16) force to remove the crowns from the teeth, whereas the counterrotational group required a mean of 42.87 kg (+/- 10.42) and the control group a mean of 42.12 kg (+/- 6.61). Analysis of variance on the force data indicated no differences among the 3 groups in the force needed to remove the castings (F[2,24] = 0.031, P = .97).

CONCLUSION

This in vitro study demonstrated no significant differences between groups in the amount of tensile dislodgment force required to remove cemented full veneer crowns from prepared teeth after brushing for the equivalent of 2 years time with a sonic toothbrush or a counterrotational toothbrush.

Evaluation of the incidence of gingival abrasion as a result of toothbrushing

The aims of the present study were: (1) to establish the incidence of gingival abrasion as a result of toothbrushing, using a manual and electric toothbrush; (2) to establish the influence of filament end-rounding on the incidence of gingival abrasion and the efficacy of toothbrushing; (3) to assess whether the speed of the electric brush has a feedback-effect on the brushing force used and to correlate the incidence of gingival abrasion with force. 2 experiments were carried out. In the first experiment, 50 subjects brushed for 3 weeks every other day with either a manual (Butler 411) or an electric toothbrush (Braun/Oral-B Ultra Plaque Remover-D9). All received brief instructions and were asked to abstain from oral hygiene 24 hrs before their appointment. After disclosing the teeth and gums with Mira-2-Tone solution, plaque and gingival abrasion were assessed. Next, the panelists brushed in a random split-mouth order. After brushing and a second disclosing, plaque and abrasion were re-assessed. The results showed that the incidence of gingival abrasion was comparable for the manual and the D9. Using a similar design as in experiment no. 1, in experiment no. 2 a new group of 47 subjects brushed for 3 weeks alternating between the Braun/Oral-B Plaque Remover-D7 and D9. At the appointment, the subjects first brushed in a split-mouth order with the D9 with 2 different types of endrounding. Plaque and abrasion were assessed. Immediately following this brushing exercise, the subjects re-brushed with the D7 (2800 rot/min) and the D9 (3600 rot/min) during which brushing force was measured. The results of this experiment showed that endrounding has no effect on plaque removal but does effect the incidence of gingival abrasion. Brushing force is not influenced by the speed of the brushhead and no correlation with the incidence of gingival abrasion was observed. In conclusion, the results of this study show that gingival abrasion is not influenced by brushing force, but is affected by filament endrounding.

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.