Original Article
Amount of toothpaste used by dental students
2023 Volume 65 Issue 4 Pages 214-218
Details
2023 Volume 65 Issue 4 Pages 214-218
Purpose: This study analyzed associations of cumulative learning, demographic characteristics, fluoride content, and toothbrush head size with the amount of toothpaste used by dental students.
Methods: Students in the third and fifth year of dental school were recruited. Each participant was asked to dispense three toothpastes (pediatric, regular fluoride, and high fluoride) on five toothbrushes (rotation-oscillation, sonic, manual pediatric, and two manual adult toothbrushes). The length and weight of the toothpaste dispensed were recorded. The data were evaluated by nonparametric correlation analysis (P < 0.05).
Results: Eighty-one students (third year = 42; fifth year = 39; mean age: 26.2 ± 5.3 years) participated in the study. More toothpaste was dispensed by third-year students than by fifth-year students (weight: P = 0.014; length: P = 0.037). Men dispensed more toothpaste than did women (weight: P < 0.001; length: P = 0.042). Participants with higher educational attainment dispensed less toothpaste (weight: P < 0.001; length: P < 0.001). The type of toothbrush was associated with the weight of toothpaste dispensed (P < 0.001). Toothbrush head size was inversely associated with the length of toothpaste dispensed (P < 0.001).
Conclusion: The amount of toothpaste used by dental students was associated with cumulative learning, educational attainment, sex, and toothbrush head size but not with the fluoride content of the toothpaste.
The most important aspect of caries prevention is effective mechanical removal of oral biofilm from tooth surfaces [1]. However, other factors, such as a healthful diet and adequate fluoride exposure, assist in preventing dental carries in primary and permanent dentition [2,3]. Fluoride use helps prevent dental caries [2,4,5], and biofilm removal in the absence of fluoride use is insufficient to prevent caries. Some evidence suggests that efficient, twice-daily toothbrushing with a fluoridated dentifrice is the most effective method for preventing dental caries [5,6,7]. Although the effect of fluoride on caries prevention depends primarily on its concentration in the toothpaste, the amount of toothpaste used, toothbrushing frequency, brushing time, and rinsing after brushing are important [8,9,10,11]. Although high fluoride concentrations are associated with better caries prevention [6,12,13], few studies have attempted to evaluate the amount of fluoridated toothpaste that must be dispensed on the toothbrush to ensure effective prevention. Use of 1 cm (or more) of fluoridated toothpaste during twice-daily toothbrushing for 2 min or longer is considered good toothbrushing practice [5], and studies of the behavioral attitudes of Nordic adolescents found that they frequently used more than 1 cm of toothpaste [14]. However, there is no consensus on the amount of toothpaste that should be dispensed for effective prevention by regular brushing.
The European Academy of Pediatric Dentistry recommendations for dispensing of fluoridated dentifrice on toothbrushes are based on the fluoride concentration of the dentifrice and the age of the child [15]. The recommended quantities of 1,000 ppm F dentifrice are 0.125 g, 0.250 g, and 0.5-1.0 g for twice-daily brushing in children aged <2 years, 2-6 years, and >6 years, respectively [15]. However, the amounts dispensed were determined by subjective measurement of parents and thus vary [16,17]. Whether the amount of toothpaste dispensed on a toothbrush is adequate is unclear because it depends on toothbrush size, the length of the paste dispensed, the diameter of the toothpaste tube opening, the pressure applied on the tube, and demographic characteristics (including age, sex, educational attainment, and economic status), which play a role in the amount of toothpaste dispensed—an important consideration, as the amount of paste in the mouth determines the amount of fluoride available. Fluoride availability is correlated with preventive action [11,14,18].
Dental behavioral attitudes are another important consideration. Studies in high-income countries with good prevention programs and policies have reported that caries-active adolescents had inadequate behavioral attitudes toward the use of fluoridated dentifrices and brushing habits [14]. Those who brushed regularly for an adequate duration, used the recommended amount of fluoridated dentifrice, and practiced limited rinsing after brushing were less susceptible to caries [8,19,20,21,22]. However, this behavior was affected by demographic characteristics such as socioeconomic status, and educational status and knowledge, and attitudes toward oral care [5,23,24]. Studies of caries prevention by fluorides have analyzed the amount of toothpaste used, dental habits and behaviors, and demographic characteristics [1,5,7,12,14,25]. However, few studies have investigated whether the amount of toothpaste used corresponds to dental literacy, or whether cumulative learning during years of dental training affects or improves use of the correct amount of toothpaste for daily oral care.
Therefore, the primary aim of this study was to evaluate the effect of cumulative learning (as students advance through the dental curriculum) on the amount of toothpaste used by dental students. The secondary objective was to determine whether the amount of toothpaste used by dental students was associated with demographic characteristics such as age, sex, marital status, socioeconomic status, and formal educational attainment (before dental school). The tertiary aim was to evaluate whether paste amount was associated with the type of fluoridated paste used (paste type) and toothbrush size (brush type). Three study hypotheses were tested:
Clarification of responsibility for this study was requested from the relevant ethics committee in Zurich (Kantonale Ethikkommission Zurich [KEK-Zurich]), which ruled that this study did not fall under the scope of the Human Research Act and that formal ethics approval was not required (BASEQ-Nr: Req-2021-00051).
Study design and settingThis single-center, cross-sectional study was conducted in the clinic of general, special care, and geriatric dentistry (ABS) in the center of dental medicine (ZZM) at the University of Zurich (UZH), in Zurich, Switzerland. Ethics clarification was sought in January 2021. Recruitment of participants and data collection were performed between 1 March 2021 and 31 May 2021. This study did not require any follow-up visits.
Participants/study populationThe study sample comprised students in their third and final (fifth) years of dental study at the ZZM of the UZH. The students were included if they consented to participate, belonged to the ZZM at the UZH, and were in the third or fifth year of the dental curriculum. They were excluded if they withdrew their consent to participate.
Study outcome/endpoints Amount of dentifrice (toothpaste) dispensedThe main outcome variable was amount of toothpaste dispensed by participants on different toothbrushes. The dispensed toothpastes were weighed after the dry weight of the empty toothbrush was measured (W1) and recorded. The participants were requested to apply the toothpaste on the toothbrush as they would for normal daily use. No other specific instructions were given to participants on how they should perform this task. The toothbrush was weighed again (W2), and the amount of toothpaste dispensed, Wtp (g), was calculated as Wtp (g) = W2-W1. This procedure was repeated for each toothpaste and toothbrush. All weights were measured with a digital laboratory balance (Entris Laboratory balance, Sartorius AG, Goettingen, Germany). Length (L1), in mm, of the toothpaste dispensed on the toothbrush head was measured and used to calculate the percentage (%) of the length of the toothbrush head covered by the paste, using the formula L (%) = (L1 / L2) / 100, where L2 was the measured length of the toothbrush head. Three types of dentifrices were dispensed on five types of toothbrushes.
Dentifrice (toothpaste) typesThe three toothpastes used in this study are commercially available dentifrices that differ in fluoride concentration and are popularly used in Switzerland, as follows:
In this study, five toothbrushes commonly used in Switzerland were studied. The shape and size of the brush heads and the method of use differed among the toothbrushes. Two toothbrushes were powered (electric) and three were manual, as follows:
The head size of these toothbrushes was measured before the experiment with a conventional analog measuring caliper (INOX, Knuth GmbH, Wasbek, Germany). One of the authors measured the sizes of 10 random samples of each type of brush, and a mean was calculated for each toothbrush type. The mean lengths and widths of the toothbrush heads are shown in Table 1.
Demographic informationBasic demographic information was collected from all participants, including age, sex, marital status, socioeconomic status, and year of study in the dental curriculum.
| Toothbrush type | Length in mm (mean ± SD) | Width in mm (mean ± SD) |
|---|---|---|
| Rotation-oscillation | 11.70 ± 0.42 | 11.70 ± 0.28 |
| Sonic | 19.15 ± 0.07 | 8.75 ± 0.49 |
| Pediatric | 17.45 ± 0.21 | 9.35 ± 0.07 |
| Manual adult (1) | 21.20 ± 0.28 | 10.60 ± 0.14 |
| Manual adult (2) | 22.30 ± 0.32 | 10.70 ± 0.28 |
SD, standard deviation
Assuming a medium effect size (ρ) of 0.30, an α err prob of 0.05, and a power (1-β err prob) of 0.80, a sample size of 64 participants (Df = 62, critical t = 1.67) was decided on for this pilot study. The sample size calculation was performed using a free software package (G*Power, version 3.1.9.6 for Mac OS X, Heinrich Heine University Düsseldorf, Dusseldorf, Germany) [26,27].
Statistical methodsDemographic information is reported descriptively. Means and standard deviations were calculated for the measured weights and lengths of the dispensed toothpaste. The Kolmogorov-Smirnov (K-S) test was used to confirm a Gaussian distribution (95% CI, P < 0.05). When data were not normally distributed (P < 0.001; K-S test), nonparametric Spearman rank-order correlation analysis was used to investigate associations of cumulative education (year of study in dental curriculum), toothbrush type, toothpaste type, and demographic characteristics (age, sex, marital status, socioeconomic status, educational attainment) with the amount of paste dispensed (P < 0.05). All statistical analysis was performed with statistical software (IBM SPSS Statistics, version 28.0.1.1, IBM corp., Armank, NY, USA).
Study protocol and proceduresParticipation in this study was completely voluntary. Students in the third and fifth year of dental school were recruited from the student pool of the ZZM at UZH. They were enrolled in the study after receiving their consent. All participants completed a form requesting demographic information and received a brief summary of the study procedure but remained blinded to the study outcome. They were instructed to dispense the various toothpastes on the given toothbrush samples as they would normally in their daily routine. Each participant dispensed three different pastes (pediatric [low fluoride], regular fluoride, and high fluoride) on five different types of toothbrushes (rotation-oscillation, sonic, manual pediatric, manual adult #1, and manual adult #2). The participants were not allowed to use the high-fluoride toothpaste with the pediatric toothbrush. The toothbrushes were weighed each time before and after the participant applied the toothpaste. The difference in weight (in grams) was recorded as the paste weight. The amount of paste dispensed was calculated by measuring the length of paste dispensed on the toothbrush head, which was expressed as a percentage of the length of the toothbrush head. Toothbrush heads were thoroughly cleaned, rinsed, and dried before being reused by the next participant. To avoid bias and errors regarding the toothpastes used, toothpaste tubes were replaced with new ones after 40% of the toothpaste had been dispensed, to ensure that the volume of toothpaste available before application was comparable in all trials. All measurements and data were anonymized.
A total of 81 students (third year = 42; fifth year = 39; mean age, 26.2 ± 5.3 years) participated in this study (response rate, 100%). Women comprised 62% of the participants, and 88.9% of participants were single. Most participants (88.9%) belonged to the middle-income group and 50.6% had a bachelor’s degree. The demographic characteristics of the study participants are shown in Table 2.
The weight of toothpaste dispensed by the participants on the toothbrushes used in the study is shown in Table 3. Third-year students dispensed a mean of 0.39 ± 0.17 g, 0.45 ± 0.22 g, 0.42 ± 0.19 g, 0.56 ± 0.26 g, and 0.54 ± 0.27 g of toothpaste on the rotation-oscillation, sonic, pediatric, manual adult (#1), and manual adult (#2) toothbrushes, respectively (Table 3). On average, the third-year students dispensed toothpaste on 68.77% to 93.7% of the length of the toothbrush head; the lowest percentage dispensed was for the sonic toothbrush (68.77 ± 15.66%). The fifth-year students dispensed a mean of 0.38 ± 0.19 g, 0.44 ± 0.22 g, 0.38 ± 0.17 g, 0.47 ± 0.26 g, and 0.46 ± 0.23 g of toothpaste on the rotation-oscillation, sonic, pediatric, manual adult (#1), and manual adult (#2) toothbrushes, respectively (Table 3). The fifth-year students dispensed toothpaste on an average of 64.33% to 93.56% of the length of the toothbrush head; the lowest percentage was for the manual adult (#2) toothbrush (64.33 ± 15.07%). Participants in both groups dispensed the maximum percentage length of toothpaste on the pediatric toothbrush (third-year students: 93.76 ± 14.58%; fifth-year students: 93.56 ± 13.17%; Table 3).
| Total | Third year | Fifth year | |
|---|---|---|---|
| Number of participants (n [%]) | 81 (100) | 42 (100) | 39 (100) |
| Mean age (±SD) in years | 26.2 ± 5.3 | 26.5 ± 6.6 | 25.8 ± 3.4 |
| Sex (n [%]) | |||
| men | 31 (38.3) | 14 (33.3) | 17 (43.6) |
| women | 50 (61.7) | 28 (66.7) | 22 (56.4) |
| Marital status (n [%]) | |||
| single | 72 (88.9) | 34 (81.0) | 38 (97.4) |
| married | 2 (2.5) | 2 (4.8) | - |
| Have children | 7 (8.6) | 6 (14.3) | 1 (2.6) |
| Socioeconomic status (n [%]) | |||
| welfare recipient | 1 (1.2) | - | 1 (2.6) |
| low | 3 (3.7) | 3 (7.1) | |
| middle | 72 (88.9) | 36 (85.7) | 36 (92.3) |
| high | 5 (6.2) | 3 (7.1) | 2 (5.1) |
| Educational attainment (n [%]) | |||
| less than high school | 1 (1.2) | - | 1 (2.6) |
| high school | 11 (13.6) | 10 (23.8) | 1 (2.6) |
| apprenticeship | 2 (2.5) | 1 (2.4) | 1 (2.6) |
| bachelor’s degree | 41 (50.6) | 25 (59.5) | 16 (41.0) |
| master’s degree | 23 (28.4) | 4 (9.5) | 19 (48.7) |
| doctorate, other | 3 (3.7) | 2 (4.8) | 1 (2.6) |
SD, standard deviation
| Rotation-oscillation | Sonic | Pediatric | Manual adult (1) | Manual adult (2) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| toothpaste | n | mean | SD | mean | SD | n | mean | SD | n | mean | SD | mean | SD | |
| Third year | ||||||||||||||
| Weight (g) | pediatric_F | 42.0 | 0.40 | 0.19 | 0.44 | 0.22 | 42.0 | 0.42 | 0.19 | - | - | - | - | - |
| reg_F | 42.0 | 0.39 | 0.16 | 0.49 | 0.24 | - | - | 42.0 | 0.59 | 0.28 | 0.54 | 0.26 | ||
| high_F | 42.0 | 0.38 | 0.15 | 0.43 | 0.20 | - | - | 42.0 | 0.53 | 0.23 | 0.54 | 0.28 | ||
| total | 0.39 | 0.17 | 0.45 | 0.22 | 0.42 | 0.19 | 0.56 | 0.26 | 0.54 | 0.27 | ||||
| Length (%) | pediatric_F | 42.0 | 94.73 | 16.99 | 64.72 | 14.48 | 42.0 | 93.76 | 14.58 | - | - | - | - | - |
| reg_F | 42.0 | 38.57 | 16.44 | 65.81 | 14.20 | - | - | 42.0 | 69.74 | 17.66 | 67.26 | 17.63 | ||
| high_F | 42.0 | 106.12 | 23.75 | 75.78 | 16.15 | - | - | 42.0 | 77.32 | 16.99 | 71.32 | 18.95 | ||
| total | 79.81 | 35.31 | 68.77 | 15.66 | 93.76 | 14.58 | 73.53 | 17.64 | 69.29 | 18.30 | ||||
| Fifth year | ||||||||||||||
| Weight (g) | pediatric_F | 39.0 | 0.40 | 0.19 | 0.49 | 0.24 | 39.0 | 0.38 | 0.17 | - | - | - | - | - |
| reg_F | 39.0 | 0.39 | 0.19 | 0.46 | 0.20 | - | - | 39.0 | 0.53 | 0.22 | 0.52 | 0.23 | ||
| high_F | 39.0 | 0.33 | 0.18 | 0.36 | 0.20 | - | - | 39.0 | 0.42 | 0.29 | 0.41 | 0.21 | ||
| total | 0.38 | 0.19 | 0.44 | 0.22 | - | - | 0.47 | 0.26 | 0.46 | 0.23 | ||||
| Length (%) | pediatric_F | 39.0 | 96.65 | 14.09 | 65.52 | 14.24 | 39.0 | 93.56 | 13.17 | - | - | - | - | - |
| reg_F | 39.0 | 39.46 | 18.86 | 64.30 | 12.16 | - | - | 39.0 | 65.39 | 12.86 | 65.31 | 13.71 | ||
| high_F | 39.0 | 100.99 | 16.87 | 66.64 | 14.66 | - | - | 39.0 | 66.88 | 18.25 | 63.36 | 16.44 | ||
| total | 79.03 | 32.67 | 65.49 | 13.64 | 93.56 | 13.17 | 66.13 | 15.70 | 64.33 | 15.07 | ||||
Rotation-oscillation, electric toothbrush; Sonic, electric toothbrush; Pediatric, pediatric toothbrush; Manual adult (1), manual adult toothbrush (1); Manual adult (2), manual adult toothbrush (2); SD, standard deviation; Pediatric_F, pediatric fluoride (500 ppm F); Reg_F, regular fluoride (1,400 ppm F); High_F, high fluoride (5,000 ppm F); g, grams; %, percentage of the length of the toothbrush
Cumulative learning was associated with the amount of toothpaste dispensed. The amount of paste used was negatively correlated with years of study. Amount of toothpaste dispensed was greater for third-year students than for fifth-year students (weight: rs [889] = −0.082, P = 0.014, Table 4; length: rs [889] = −0.070, P = 0.037, Table 5).
| Paste amount | Year of study | Age | Sex | Marital status | Socioeconomic status | Education level | Toothpaste type | Toothbrush type | |
|---|---|---|---|---|---|---|---|---|---|
| Weight | rs | −0.082* | 0.008 | −0.162** | 0.044 | 0.058 | −0.150** | −0.023 | 0.186** |
| P-value | 0.014 | 0.824 | <0.001 | 0.193 | 0.083 | <0.001 | 0.501 | <0.001 | |
| n | 891 | 880 | 891 | 891 | 891 | 891 | 891 | 891 | |
| df | 889 | 878 | 889 | 889 | 889 | 889 | 889 | 889 |
rs, Spearman’s rho correlation coefficient; *P < 0.05; **P < 0.01
| Paste amount | Year of study | Age | Sex | Marital status | Socioeconomic status | Education level | Toothpaste type | Toothbrush type | |
|---|---|---|---|---|---|---|---|---|---|
| Length (%) | rs | −0.070* | −0.006 | −0.068* | 0.036 | 0.008 | −0.117** | −0.068* | −0.146** |
| P-value | 0.037 | 0.868 | 0.042 | 0.28 | 0.806 | <0.001 | 0.043 | <0.001 | |
| n | 891 | 880 | 891 | 891 | 891 | 891 | 891 | 891 | |
| df | 889 | 878 | 889 | 889 | 889 | 889 | 889 | 889 |
rs, Spearman’s rho correlation coefficient; *P < 0.05; **P < 0.01
Demographic characteristics such as participant sex and educational attainment were associated with amount of toothpaste dispensed on toothbrushes. Men used more toothpaste than did women (weight: rs [889] = −0.162, P < 0.001, Table 4; length: rs [889] = −0.068, P = 0.042, Table 5).
Participants with higher educational attainment used less toothpaste (weight: rs [889] = −0.150, P < 0.001, Table 4; length: rs [889] = −0.117, P < 0.001, Table 5). Other demographic characteristics, such as age, marital status, and socioeconomic status, were not associated with amount of toothpaste dispensed.
Association of toothpaste type and toothbrush type with paste amountToothbrush type, but not toothpaste type, was associated with the weight of toothpaste used (weight: rs [889] = 0.186, P < 0.001, Table 4). However, both toothpaste type and toothbrush type were associated with the length of toothpaste used. Toothpastes with lower fluoride content and smaller toothbrushes were associated with greater length of toothpaste dispensed on toothbrushes (toothpaste type: rs [889] = −0.068, P = 0.043; toothbrush type: rs [889] = −0.146, P < 0.001; Table 5).
This study investigated whether toothpaste use by dental students was associated with cumulative learning (educational experience in dental school), demographic characteristics (age, sex, socioeconomic status, educational attainment), toothbrush head size, and toothpaste type (low, moderate, or high fluoride content) used. Three study hypotheses were established. A sample size calculation was performed for this pilot study by assuming a medium effect size (ρ) of 0.30 with an α err prob = 0.05 for a power (1-β err prob) of 0.80. The number of participants required to avoid sampling error in this pilot study was 64 [26,27]. The participation rate for the invited students was 100%; 81 students were recruited and the required sample size was achieved.
The results revealed that cumulative learning was associated with toothpaste use. Fifth-year students used less toothpaste than did third-year students. Therefore, the primary null hypothesis of this study was rejected. In addition, sex and educational attainment were associated with the amount of toothpaste used: women used more toothpaste, and participants with higher educational attainment used less toothpaste. However, associations of toothpaste amount with other demographic characteristics—age, marital status, and socioeconomic status—were not significant. Hence, the secondary hypothesis was partially rejected.
Furthermore, the present results revealed a complex relationship between the size of the toothbrush head and the amount of toothpaste dispensed by students. Paste amount was evaluated by measuring the weight and length of toothpaste dispensed on the toothbrush head. The length of paste dispensed was greater for smaller brush heads. Moreover, the weights measured were also significantly more, both on the smaller and larger brush heads. There was no association between toothpaste type and toothpaste weight, but the dispensed toothpaste length was shorter when fluoride content was higher. Hence, the tertiary hypothesis was partially rejected.
Although this pilot study strictly adhered to good research principles and methods, some limitations warrant mention. The generalizability of the results is a concern because the study was performed in just one of the four dental schools in Switzerland. However, because this was a pilot study, recruitment from other dental schools in Switzerland was deemed unnecessary. Furthermore, students at the ZZM come from various Swiss-German-speaking regions in and around the city and canton of Zurich. Moreover, the current study cohort included participants who were not native to Switzerland. Therefore, the participant pool may be considered balanced. Although the current cohort may not be representative of the general Swiss population, the results are likely generalizable to the Swiss-German-speaking regions.
This study did not evaluate all toothpastes and toothbrushes available in the Swiss market, which could be regarded as a limitation. However, such a study was not feasible. Nevertheless, the present toothpastes and toothbrushes are commonly available in Switzerland and were carefully selected. Pediatric and both regular and special adult toothpastes were used to ensure inclusion of toothpastes with various recommended fluoride concentrations. The pediatric toothpaste had a low fluoride concentration (500 ppm F), while the regular and special adult toothpastes had moderate (1,400 ppm F) and high (5,000 ppm F) fluoride concentrations. Although numerous dentifrice formulations are marketed in Switzerland, these three formulations are most frequently recommended by dental professionals to patients with varying ages and oral care needs.
Similarly, only five types of toothbrushes of the many that are commercially available were evaluated. The current toothbrushes were selected after determining the relevant criteria. Both manual and powered toothbrushes were included. The former included a pediatric toothbrush and two commonly used adult toothbrushes. This ensured a clear distinction between manual toothbrushes. Two manual adult toothbrushes were included to allow for evaluation of two toothbrush head sizes. Although the difference in head size between the two adult brushes was not large, these toothbrushes were retained to limit errors due to selection bias. Two generic types of powered toothbrushes were studied—a rotation-oscillation brush and an ultrasonic brush. These powered toothbrushes are the most popular currently marketed types. The rotation-oscillation toothbrush, as the name suggests, works by rotation-oscillation movement with a designated number of repeated head movements. It has been very popular and highly recommended for almost 25 years and its efficacy has been demonstrated [28,29,30]. Sonic powered brushes are becoming more popular and are efficient in plaque removal but inferior to rotation-oscillation powered brushes [31,32,33]. Plaque is removed by bristle vibrations on the tooth surfaces at ultrasonic levels. There is no to-and-fro motion of the brush head, only vibratory movement. However, brush head size was the main criterion used to select these powered brushes: the rotation-oscillation toothbrush has a small circular head, while the sonic toothbrush has a standard toothbrush head. Therefore, including one without the other might have influenced the results of this experiment.
Another limitation of this study is that the toothbrush heads were not replaced before each trial. This was not possible logistically because of the cost and other factors, such as time and product availability. This pilot study was self-funded and research funds were not available for the purchase of elaborate or expensive materials. Therefore, although the manual toothbrushes were unique to each participant, the electric brush heads were recycled. The protocol for recycling the brush heads was standardized: after each participant use, the dispensed paste was completely removed from the heads, which were then rinsed thoroughly, dried, and then reused. Most importantly, the toothbrushes were always weighed before and after the participant dispensed the toothpaste, to calculate the actual weight of the paste. Hence, recycling of the toothbrush heads likely had a negligible effect on the results.
A similar limitation is the decision not to give each participant a new tube of toothpaste, because of budget and other practical considerations. The tubes were replaced when they were assessed to be 40% empty, as determined by weighing the tube to verify the original weight before use. The decision to change tubes was made to ensure that dispensing was standardized and not influenced by the amount of paste remaining in the tube. This eliminated the need for varied application of force by participants. Nevertheless, participants may have used varying levels of force, which, along with characteristics such as physical status and sex, may have affected paste application. However, these characteristics, if present, likely had a negligible effect on the results.
The strengths of the current study include its methodological rigor. This study may be considered robust, as all the above limitations were addressed with the best possible methods. To ensure standardization, a single author performed all the data collection, which addressed the possibility of errors related to non-calibration of multiple investigators. Measuring techniques were standardized and performed by a single author so that they were repeatable and reproducible.
The participants were blinded to the precise objective of the study, which limited the possibility that they would be influenced by this knowledge while dispensing the toothpastes. Only the type of toothpaste was known to the participants. Because they were not given specific instructions, dispensing of the paste by the participant was not affected by bias. Another important strength of this study is that the required sample size was achieved and hence the possibility of inaccuracy due to statistical errors was excluded [28]. Moreover, the 100% participation rate for the enrolled students ensures that inclusion bias is not a concern and could not have affected the results.
Mechanical oral biofilm removal is essential for preventing oral diseases. Other important aspects of successful removal of dental plaque are proper technique and use of the correct instruments, complimented by use of an effective dentifrice formulation. Many toothpastes and toothbrushes are currently available. The choice of a toothbrush is usually based on professional advice and personal preference. Although toothpastes are also chosen based on personal preference, professional advice plays a larger role because there are important characteristics to consider, such as fluoride content. Although regular fluoride toothpastes are common, toothpastes with low and high fluoride concentrations are also available. Pediatric toothpastes have low levels of fluoride (≤500 ppm F) because of age-related restrictions on fluoride for children. High-fluoride toothpastes (>2,500 to 5,000 ppm F) are recommended for adults at high risk for dental caries [13]. Regardless of the type of toothpaste selected, an acceptable amount of toothpaste must be used during toothbrushing and maintained in the mouth for a sufficient period of time to yield effective prevention.
Existing evidence is unclear regarding the amount of toothpaste to be dispensed on a toothbrush for daily use, and there are no recommendations that indicate the amount of toothpaste to be used for a specific toothpaste formulation and toothbrush type. This pilot study was undertaken as a first step to evaluate the amount of toothpaste dispensed during normal daily use.
The average amount of toothpaste dispensed by the present third-year dental students was between 0.39 g and 0.56 g, and occupied 69% to 94% of the length of toothbrush head. Fifth-year students dispensed an average of 0.38 g to 0.46 g of toothpaste on approximately 64% to 94% of the toothbrush head. The values for the fifth-year students, while similar to those for third-year students, are nevertheless significantly lower. The fifth-year students were nearing graduation and likely knew the potential benefits and side-effects of dentifrices with varying fluoride concentrations. Therefore, they may have dispensed the pastes more judiciously. This is consistent with previous reports that greater dental knowledge had a significant effect on brushing habits [12]. Furthermore, a previous study found that African American teenagers and children used more toothpaste than did their White and Hispanic peers and that teenagers and children with higher disposable incomes used less toothpaste than did those below the poverty line [25]. That study reported associations of age group, race, and income level with the amount of toothpaste used by children; however, sex and educational background of the head of household were not associated with the amount of toothpaste used. The present results showed no association with age or income level but sex and educational status played a role, perhaps because quality of life is similar, and the cost of living is affordable, for most Swiss. The associations with educational status and sex [12] could be attributable to differences in habits, as confirmed in a previous study [12,25,34].
Previous studies reported correlations between social background and amount of toothpaste used, but these correlations differed by country. In the present study, fluoride content was not associated with the amount of paste dispensed, which is consistent with previous findings [12,25,34]. This result requires confirmation in studies designed to evaluate this outcome, which was beyond the scope of this study.
In summary, cumulative learning, educational attainment, and sex were associated with the amount of toothpaste used by dental students. The size of the toothbrush head appeared to affect the amount of toothpaste used, but fluoride concentration did not.
The authors declare no conflict of interest. This research was conducted in accordance with the research guidelines of Zurich University.
The authors thank the dental students at the University of Zurich who volunteered to participate in this study and acknowledge the support of Elena van der Heijden, of the Clinic of General-, Special care-, and Geriatric Dentistry in the Center of Dental Medicine (ZZM), for her help in successfully completing the study.
