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Year : 2019  |  Volume : 37  |  Issue : 3  |  Page : 292-296

Comparing the effect of dry and wet brushing on dental plaque removal in children

1 Department of Paediatric Dentistry, School of Dentistry; Dental Research Center, Research Institute of Dental Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran
2 Dental Research Center, Research Institute of Dental Sciences, Shahid Beheshti University of Medical Sciences; Department of Operative Dentistry, School of Dentistry, Tehran, Iran
3 Department of Oral and Maxillofacial Radiology, School of Dentistry, Mazandaran University of Medical Sciences, Sari, Iran
4 Department of Paediatric Dentistry, School of Dentistry, Tehran, Iran

Date of Web Publication30-Sep-2019

Correspondence Address:
Dr. Paniz Sheikh Hassani
Department of Paediatric Dentistry, School of Dentistry, Shahid Beheshti University of Medical Sciences, Velenjak, Tehran
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/JISPPD.JISPPD_71_19

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Aims: This study was aimed to assess the efficacy of wet and dry brushing on cleaning outcome of tooth surfaces. Methods: Forty-three children aged 10–12 years were randomly selected and instructed for this brushing project. Each case served as self-control. Each patient was requested to brush through one of the wet/dry techniques for 1 week and other technique on the 2nd week. Samples had a washout step using pumice prophylaxis prior to each brushing week. Tooth Cleanliness Index was used to measure the plaque removal level. Two uniform Oral-B toothbrushes were used one for each week through the Modified Stillman technique. Mann–Whitney test was employed along with the Wilcoxon signed-rank test to analyze the data. Results: The level of brushing efficacy was slightly higher in males with no statistically significant difference between sexes. Remaining plaque measured was higher in wet group with significant difference (7.3 ± 1.7 for dry brushing and 7.6 ± 2.6 for wet brushing) (P < 0.05). Conclusions: Dry and wet brushing did not show a significant difference in their capacity to remove plaque indicating that dry brushing could be considered as an acceptable brushing technique.

Keywords: Children, dental plaque, dry, toothbrushing, wet

How to cite this article:
Ansari G, Torabzadeh H, Nabavi ZS, Hassani PS. Comparing the effect of dry and wet brushing on dental plaque removal in children. J Indian Soc Pedod Prev Dent 2019;37:292-6

How to cite this URL:
Ansari G, Torabzadeh H, Nabavi ZS, Hassani PS. Comparing the effect of dry and wet brushing on dental plaque removal in children. J Indian Soc Pedod Prev Dent [serial online] 2019 [cited 2022 Aug 17];37:292-6. Available from: http://www.jisppd.com/text.asp?2019/37/3/292/268188

   Introduction Top

For many years, the risk of swallowing large amounts of toothpaste by young children has made pediatric dentists concerned over the use of fluoridated toothpaste in very young. Several experimental and epidemiological studies have demonstrated the role of microbial plaque as one of the main causes of dental caries and periodontal diseases.[1] It has been shown that there is a significant correlation between dental hygiene and a rise in caries, periodontal, and cardiovascular disease risk factors.[2]

Appropriate and efficient brushing is a key to microbial plaque control, which includes initial removal as well as maintaining teeth and gum's health.[3] Mechanical and chemical methods are still considered as the most reliable methods for dental plaque control.[4],[5] Proper brushing method is instructed by dental professionals, with an important role played in oral health maintenance of different age groups. The old tradition to supposedly wash the toothbrush before use has currently been practiced by many different communities with varying ethnicity which in fact makes the toothbrush wet. This wetting step is effective on the flexibility and strength of the toothbrush bristles and their clinical performance.[1]

Early childhood caries is mainly caused by lack of appropriate oral hygiene while having a high sugar intake. There are substantial reports on the causative role of bottle milk for early caries development in children with little to no attempt to brush afterward.[6] It is clearly evident that fluoridated toothpaste could directly effect on the mineralization of enamel and therefore reducing the chance of demineralization. The use of toothbrush without toothpaste is believed to have no effect on the bacterial flora and only displaces them within the oral cavity. Children younger than the age of two are also proved to be unable to expectorate and therefore the formation of high volumes of toothpaste foam would bring the child to an unavoidable status of swallowing the oral content. Repeated effect of such action is believed to be a possible cause of future teeth discoloration in the line of fluorosis. Many pediatric dentists prefer to advise parents not to use any toothpaste for their young children to avoid such complication.[2]

The use of wet toothbrush is normally expected to enhance the attrition of the bristles, making them bend, and become ineffective much quicker. Finest nylon bristles are shown to lose their firmness up to 27% when fully saturated with water; therefore, the toothbrush becomes softer than the time it is applied dry. The stiffness of nylon toothbrush can be largely predicted based on quality, height, and thickness of the filaments.[7] Many factors raise the quality of nylon fiber, including water absorption potential and resistance to dislocation, wear, and flex. When the absorption coefficient is high (in toothbrushes with low-quality nylon), toothbrush is very soft and may bend further. It will even become harder after being dried which is undesirable. The duration of consistency loss is relatively high in high-quality nylon, while this duration is very short in low-quality nylon.[7],[8] As moist absorption can directly influence on bristles' consistency, it is therefore expected to make them softer than what it has been designed for. This could, in turn, reduce the force needed to remove the entire dental plaque and may leave some remaining at the surface of the tooth. Usually, the hardness of the selected toothbrush (hard, medium, or soft) is important and specifically advised for relative users. The nylon diameter has been increased by producers in order to reduce the wettability following an increased inconsistency. However, it is believed that such product with thick bristles would be harder and exaggerated in their consistency when used dry.[7]

Studies have shown that hard filament toothbrushes remove more plaque and cause more gingival abrasion.[9],[10] Successful brushing can be achieved if original hardness of toothbrush bristles is maintained.[11] It is suggested that even soft bristle design can successfully help removing dental plaque.[12]

It is also believed that toothbrushes with round bundle head have less cleaning effect, as their long bristles prevent proper cleaning of all areas. Straight fibers of nylon with thin diameter trim head are considered more effective. Furthermore, it is probable that trimmed fibers enter directly into the space between the teeth in a more effective fashion.[8] It is generally believed that the round tip fibers are significantly more effective in cleaning different surfaces. It has been reported that toothbrushes with nonround tip bristles cause gingival trauma as well as a 30% more wearing rate of the gum.[7]

The bent bristles of the toothbrush are normally considered as wear, and it seems to occur within 2–3 months of its starting point of use in wet condition.[13],[14],[15] There are also reports suggesting that the role of toothbrush wear is not considerable in plaque removal quality.[16] However, several other reports have recently suggested significant differences between the capacity of plaque removal of new and used toothbrushes.[17],[18],[19],[20] Tan and Daly concluded that no significant differences could be seen in the amount of plaque remaining between the participants who used one toothbrush for 3 months and those who changed their toothbrush each month.[19] Based on the American Dental Association's recommendation, toothbrushes must be changed after 3–4 months of use, or when bristles are damaged and bent. Bristles' wear depends on individual's habits, e.g., frequency and duration of use and force and technique used when brushing. Therefore, bristles' wear is a determinant parameter of changing toothbrush rather than its age.[21]

The aim of this cross-over clinical investigation was to compare the plaque removal efficacy of dry and wet brushing in children.

   Methods Top

This cross-over clinical investigation was conducted on a group of 50 Iranian 10–12-year-old schoolchildren at their school. Data were recorded for each patient based on a thorough clinical observation and detailed examination of their performance before and after each step of instructed brushing with data being recorded in special forms provided. The study has been independently reviewed and approved by the Institutional Ethical Committee Board of Shahid Beheshti University of Medical Sciences, having ethical approval number 2011070614167. An introductory session was set with potential participants being invited, joining on their personal will. Informed consent was obtained from all parents prior to the start of the investigation.

Sample size estimation was based on Versteeg et al. (2005) with 15% standard deviation leading to the minimum sample size of forty cases. To reduce the chances of disruption by probable loss to follow of 20%, the final sample size was calculated at fifty cases.[22]

Children aged 10–12 years were included with fully erupted central incisors and first permanent molars. Cases were randomly divided into two groups for starting brushing technique with one of the two to eliminate the sequence effect. Instructions were given to both child and accompanying parent for brushing technique to be adopted in each episode.

Children in Group I were instructed to brush using dry technique with a pea-sized unique toothpaste, while those in Group II were instructed to use wet technique with pea-sized toothpaste for a period of 1 week. A 1-week washout period was also considered after which the second experimental week was started by the other technique.

Assessment of dental plaque was performed at the buccal surfaces of teeth 11, 16, and 26, and lingual surfaces of teeth 31, 36, and 46 using Replaque solution (Dentsply, in cooperation with Faqihi's Co., Tehran, Iran) applied to the teeth surfaces using a microbrush. This measurement was carried out in several steps including the first visit before starting the technique, at the end of the 1st week, after the washout period, and at the end of the second step of the experiment. Observations were made using Tooth Cleanliness Index (TCI).[23] An initial in-office plaque removal was performed for all cases using pumice prophylaxis and a rubber cap in order to achieve zero plaque status. Modified Stillman brushing method was instructed and parents were instructed for a close supervision. A unique brand toothbrush (Vision, Oral-B product, USA) with a Crest children's toothpaste (Procter and Gamble Co., USA) were given to each child. Participants were asked to strictly use the toothbrush and toothpaste provided during each course of the study (1 week).

A new set of toothbrush was provided for the second step (2nd week) to eliminate the bristles possible attrition effect. Participants were asked to use the new toothbrush, only, during the 2nd week.

Wilcoxon signed-rank test and Mann–Whitney test were used ran by IBM SPSS Statistics for Windows, version 24.0 (IBM Corp., Armonk, NY, USA) to elaborate the possible differences between groups.

   Results Top

Overall, 43 children were included in this study from which three cases did not follow for the second visit and were omitted. Among the rest of 40 participants, 21 used dry brushing technique as instructed for their 1st week, while the other 19 used wet brushing first. Among the population of this study, 28 (70%) were female and 12 (30%) were male.

Fifteen of the participants (37.5%) were the first child, and the rest were either the second or later in sequence. Sixteen participants (40%) were in Grade 4, and the rest were in a single step higher grade. Most of the participants were attending public schools (87.5%) and the rest were in private schools (22.5%) with annual tuitions. Among the parents of these children, 9 (22.5%) were in administrative jobs, 24 (60%) were self-employed, and 3 (7.5%) had other job titles.

Mothers were less educated with 21 (52.5%) being under diploma, and only 7 (17.5%) had a university degree. The teeth investigated were classified in four groups for data analysis: upper right central incisors (T11); upper posterior teeth (T16) which includes the maxillary left and right first molars; left mandibular central incisors (T31); and lower posterior teeth (T36) which includes the right and left first mandibular molars.

To investigate the effect of time (considering a week washout period), the Mann–Whitney test was employed with results indicating none of the variables showing any significant difference from others. Considering the carry-over effect, Wilcoxon signed-rank test was used with the P < 0.05. This issue did not represent any significant difference either.

The main comparison was between dry and wet brushing techniques with their effect being tested by means of Wilcoxon signed-rank test. Result of this test was very close with no significant difference between the two techniques [Table 1]. [Table 2] demonstrates the different effects of parameters on plaque removal.
Table 1: Dental plaque on sample teeth brushed through dry and wet techniques

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Table 2: The mean plaque score in children at different groups

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   Discussion Top

For long, it has been the focal point in the mind of many dental research groups to find an effective and consistent microbial plaque removal technique. Various methods have been tested to improve the quality of such clinical performance among young children. Different elements have been investigated for their effect on brushing outcome with the toothbrush wetness remained as an issue. Result of the current study indicates that both techniques of dry and wet are equally effective and capable to sufficiently eliminate plaque. The importance of the point is highlighted when young children are expected to use fluoridated toothpaste while brushing daily. This routinely gives rise to the concerns over the risk of fluoride intake level which may pass the safe limit. By knowing the efficacy of dry brushing as similar to the wet, it appears that children may use a dry toothbrush instead and therefore being in a lower risk of overfluoridation.

Based on Hogan et al., the mean plaque removal value did not differ significantly when used and new toothbrushes were compared.[16] In contrast to earlier reports, Glaze and Wade concluded that samples that used a single toothbrush for 10 weeks had more remained plaque compare to those who replaced it every 2 weeks.[17] Based on Rosema et al., the age of a toothbrush is not a determining factor in plaque score reduction. The wear level of the bristles is known to be directly influencing the effectiveness of brushing.[24] However, for a more secure status, the toothbrushes used in the first and second phases of the current study were both newly opened for use. It is demonstrated that toothbrush depreciation has a direct effect on its ability to remove plaque. Although new toothbrushes are able to remove more plaque, this difference is so little, with no significant difference among the groups.[18],[19],[20],[25] A considerable amount of toothbrush wear depends on its head design. It is demonstrated that the retention of plaque is longer in a rectangular toothbrush and those with shorter bristles with different heights. It was also shown that the toothbrush used for <2 months had better plaque removal due to lack of significant wear.[26],[27]

Samples were monitored and emphasized to use only the given toothbrush for each phase of the study to eliminate the bristles quality difference. Meanwhile, a unique toothpaste was administered same as the routinely recommended and available one for children. Attempts were made to ensure the use of similarly formulated toothpaste with special attention to avoid using antiplaque formation materials.

Sgan-Cohen and Vered indicated that a significant increase has been noted in the amount of plaque removal after 60 days compare to that of the 30 days, with a clear training effect based on brushing improvement.[8] In cases of this study, a significant increase was also observed at the end of the 1st week compared to their 1st day using the “TCI.” However, the rise in plaque removal capacity continued in the 2nd week in a lower rate. The role of continuous training should strongly be noted. Patients' knowledge of general health is promoted by oral health education. This may include programs in schools affecting children's lifestyles with improved personal care while reducing costs involved.[28]

Training an appropriate method of brushing could significantly improve the capacity of microbial plaque removal in children with little effect from the toothbrush design.[29] However, a recent study has also indicated that a single brushing instruction does not greatly influence on plaque reduction of young adults.[30] Only one demographic parameter, “mothers' educational level” was significantly influencing the plaque removal amount. As it is clear, the difference in the amount of plaque was only significant in the two parameters, namely father's occupation (P = 0.01) and mother's education level (P = 0.03). It appears to be that by every single increase level in maternal education, the success rate is 0.3 units greater in plaque removal.

   Conclusion Top

  1. There is no difference between brushing by a dry or wet toothbrush
  2. As dry brushing could cause a lower volume of toothpaste foam, it may be considered safer for young children for an effective length of brushing
  3. Dry brushing could also provide a better-cleaned surface compare to when it is wet due to the filament's flexibility rise following wetness.


The authors would like to express their appreciation for the financial support provided by Dental Research Centre, Research Institute of Dental Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran, with the grant number 201107069004. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

The study was financially supported by the Dental Research Centre, Research Institute of Dental Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

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  [Table 1], [Table 2]


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