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ORIGINAL ARTICLE
Year : 2020  |  Volume : 23  |  Issue : 4  |  Page : 545-549

Investigating the effect of handedness on the dental caries pattern, gingival index, and plaque index in 6–10 years old children


1 Department of Pediatric Dentistry, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran
2 Department of Pedodontics, Private Practice, Tehran, Iran
3 Department of General Practitioner, Private Practice, Tehran, Iran
4 Department of Pediatric Dentistry, Tehran University of Medical Science, Tehran, Iran

Date of Submission01-Nov-2019
Date of Acceptance07-Dec-2019
Date of Web Publication4-Apr-2020

Correspondence Address:
Dr. N Tavana
Department of Pediatric Dentistry, School of Dentistry, Tehran University of Medical Sciences, Amirabad St. Tehran
Iran
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/njcp.njcp_600_19

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   Abstract 


Background: Handedness is one of the individual characteristics that causes different mental and practical capabilities including different abilities to perform oral hygiene instructions. It seems that the right-handed and left-handed individuals have different ability in brushing and removing plaque at different areas of the mouth. Aims: To investigate the effect of handedness on decay pattern, gingival index, and plaque index in 6–10 years old children. Subjects and Methods: In this cross-sectional study, children 6–10 years of age who fulfilled the inclusion criteria were selected. Dental caries and plaque and gingival indices were also measured and recorded for each child. Then the relationship between the handedness and the recorded variables was evaluated. Independent t-test and nonparametric Mann–Whitney test were used for the statistical comparison of quantitative variables between two right-handed and left-handed groups and Chi-square test was used for the statistical comparison of qualitative variables between these two groups. Data were analyzed using SPSS software version 20. Results: The results showed that there was no significant relationship between any of the variables with being left- or right-handed. A significant relationship was observed only between the lowest plaque index and handedness (P < 0.05). Conclusion: A relationship cannot be considered between the handedness of children and their oral health status.

Keywords: Dental caries, dental hygiene, handedness


How to cite this article:
Mokhtari S, Sanati I, Babaki F A, Alamdari S, Tavana N. Investigating the effect of handedness on the dental caries pattern, gingival index, and plaque index in 6–10 years old children. Niger J Clin Pract 2020;23:545-9

How to cite this URL:
Mokhtari S, Sanati I, Babaki F A, Alamdari S, Tavana N. Investigating the effect of handedness on the dental caries pattern, gingival index, and plaque index in 6–10 years old children. Niger J Clin Pract [serial online] 2020 [cited 2020 Nov 24];23:545-9. Available from: https://www.njcponline.com/text.asp?2020/23/4/545/281934




   Introduction Top


Dental caries is one of the most common infectious diseases that has a multifactorial etiology, mainly related to the eating habits and lifestyle.[1] In dental caries, the hard tissue loses calcium and phosphorus minerals as a result of acid secretion caused by cariogenic bacteria (mainly Streptococcus mutans) and fades gradually in this disease.[2] Good oral hygiene is an important factor for preventing dental caries and periodontal disease, and effective removal of dental plaque plays a great role in maintaining oral health. Manual tooth brushing is highly effective if performed in a correct manner and specified time. It remains the most efficient long-term means of removing dental plaque in children.[3]

Children's ability to use the toothbrush varies greatly according to their age, individual dexterity, and motivation. Improving the ability to brush occurs with age up until age 10 years due to increasing of motor competence. Children develop gross motor skills prior to fine motor skills and these skills continue to build upon each other as children grow older.[4]

It seems that the right-handed and left-handed individuals have different ability in brushing and removing plaque at different areas of the mouth. What causes determining being dominant of a hand in individuals is the dominant hemisphere of brain. Handedness, language understanding, and speech are related to the practical behavior which is conducted by monitoring the dominant hemisphere in most individuals, and over 90% of adult individuals are right-handed as a result of the left hemisphere dominance.[5]

Although the impact of handedness on gingivitis and dental plaque is still under debate, some believe that this can cause differences in oral hygiene and health status of individual.[6] Whether an individual prefers which hand depends on the center of cerebral activity, neuromuscular structure, and genetic factors.[7]

According to this issue, the methods of oral hygiene education and strategies for prevention can be different with each other in the right-handed and left-handed people to result in enough plaque removing at different areas of the mouth.[5] This research aims to investigate the effect of handedness on decay pattern, gingival index (GI), and plaque index (PI) in 6–10 years old children.


   Subjects and Methods Top


All stages of this cross-sectional study were approved by the Ethics Committee of Shahid Beheshti University of Medical Sciences. Children 6–10 years old from two primary schools were investigated at a region in Tehran. Individuals who were healthy and were not taking medication or under orthodontic treatment were included in the study. Informed consent was also obtained from parents of all subjects who participated in the study.

Among all children, 140 had fulfilled the inclusion criteria. Handedness of students was determined according to Edinburg questionnaire.[8] Overall, 29 and 129 children were placed, respectively, in the left-handed and right-handed groups. Applying a pilot study revealed that this sample size is acceptable for the study. The parents were asked about responsible individual for tooth brushing of children.

The students were then examined in a room with proper light by a trained dentist using a mirror and dental probe and their DMFT and dmft indices were calculated separately. Examination of all students was done by one person. GI (Loe and Silness 1963) was also determined in each quadrant as 0–3 (0 = normal gingiva, 1 = mild inflammation, slight change in color, and no bleeding on probing, 2 = moderate inflammation, redness, edema, and glazing, or bleeding on probing, 3 = severe inflammation, redness and marked edema, tendency to spontaneous bleeding, and ulcer).[9] Furthermore, the PI (Silness and Loe 1964) was measured for each sample in each quadrant.[9] A number (1–4) was assigned to each quadrant according to the percentage of PI to facilitate the record of PI. A score of 1 and 4 showed, respectively, the lowest and highest amount of PI. In fact, these numbers specified the sequence of quadrants in terms of the PI.

Independent t-test and nonparametric Mann–Whitney test were used for the statistical comparison of quantitative variables between two right-handed and left-handed groups and Chi-square test was used for the statistical comparison of qualitative variables between these two groups.

The multivariate linear regression models were used in the quantitative implications of study due to presence of the confounding factors. Data were analyzed using SPSS software version 20.


   Results Top


A total of 140 children age 6–10 years old were investigated, among which 111 children (including 53 boys and 58 girls) were right-handed and 29 children (including 17 boys and 12 girls) were left-handed in this study. In all cases, brushing was conducted by children themselves. The descriptive results of the studied variables are shown in each right- and left-handed group in [Table 1]. There was no significant difference between genders in the studied variables.
Table 1: Descriptive statistics of the studied variables separately for the right- and left-handed subjects

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Comparing the quantitative variables (including DMFT, dmft, age, and number of brushing per day) in both genders using Mann–Whitney test, the results showed no significant difference between both genders and the DMFT difference between genders was borderline (P = 0.56) and DMFT was slightly more in girls.

Investigation of the relationship between age and number of brushing per day with right/left hand also showed that these factors are not affected by the handedness; in other words, there is not a significant difference between two groups in terms of these factors (P > 0.5).

The gingival index

The results of comparing the GI showed that 53 samples (38%) had normal gingiva, 56 individuals (40%) had mild gingivitis, and 31 (22%) had moderate gingivitis, and severe gingivitis was not seen between samples.

Among the left-handed children, most samples (about 51%) had normal gingiva (no gingivitis), while most individuals (65%) of the right-handed group showed a mild or moderate gingivitis. However, there was no significant relationship between the GI and handedness (P = 0.19).

The plaque index

The results of evaluating the PI are shown in [Table 2] and [Table 3]. [Table 2] and [Table 3] show the maximum and minimum PI, respectively.
Table 2: Relationship between the handedness and the quadrant with most plaque index using Chi-square test

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Table 3: Relationship between the handedness and the quadrant with least plaque index using Chi-square test

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Overall, the most PI was seen mostly in the lower left quadrant (37%). However, the most PI was seen in the upper right, lower right, and upper left quadrants in 21%, 20%, and 20% of subjects, respectively.

The lowest PI was seen mostly in the lower right quadrant (48%), followed by the upper left (23%), upper right (17%), and lower left (12%) quadrants.

Among the right-handed individuals, the most PI was often observed in lower left quadrant (40% of the right-handed group), followed by the upper right quadrant (22% of the right-handed group), and this often was observed among the left-handed individuals in the lower right and left quadrants (62% of the left-handed group).

Among the right-handed subjects, the lowest PI was often observed in the lower right quadrant followed by the upper left quadrant and this often was observed among the left-handed subjects in the lower right quadrant followed by the upper right.

The ratio of right-handed to left-handed individuals was also specified in each quadrant to evaluate the relationship of handedness with the lowest PI in each quadrant. Accordingly, the lowest PI was five to six times more in the right-handed than the left-handed individuals in the quadrants of the upper left and lower right, respectively, and this difference was statistically significant.

Despite this, the most PI was five to six times more in the right-handed individuals in the quadrants of lower left (32%) and upper right (18%), respectively, but this difference was not statistically significant.

The quantitative variables of study (DMFT, dmft)

Both Mann–Whitney test and independent t-test did not show a statistically significant relationship between quantitative variables (including DMFT, dmft) and handedness. Although the mean DMFT and dmft was different between the right- and left-handed individuals, it was not statistically significant. The multivariate linear regression which was used to investigate the relationship of handedness with PI, GI, dmft, and DMFT considering the subjects' age and gender showed that there is no statistical relationship between any of the studied variables and handedness (P > 0.05).


   Discussion Top


Having good oral hygiene is one of the important and effective factors in oral and dental health and usually has a close relationship with the GI, PI, and dental caries. Handedness is one of the individual characteristics that causes the different mental and practical capabilities including different abilities to perform oral hygiene instructions.[10]

In left-handed individuals, the right hemisphere of the brain is dominant. The hemispheres of the brain have differences with each other structurally and functionally and each one has been specialized for specific cognitive functions. Therefore, right-handed and left-handed individuals are different in terms of mental and practical performances.[11],[12] For example, left-handed individuals usually work better than right-handed ones in music and painting. Several studies have also compared the various mental and practical aspects in these two groups.[13],[14] In addition to the mental performance, some studies have compared other aspects between left- and right-handed people. Orbak et al.[15] state that tooth eruption sequence is different between these two groups. In another study, Ciçek et al.[16] suggest that left-handedness appears to be a predictor factor for recurrent aphthous stomatitis. The relationship between the handedness and the ability to maintain good oral hygiene was investigated using some indices in this study. There was no statistically significant relationship between the handedness and the GI in the different quadrants.

In terms of the PI, a significant relationship was not seen between the most PI and handedness; but there was a significant relationship between the lowest PI and handedness, although the most PI was five to six times more in right-handed individuals in the upper right and lower left quadrants.

Because the GI and handedness had no significant relationship, therefore, the significant difference that is seen in the least PI of the right-handed and left-handed individuals probably has no clinical importance; because if the handedness had a significant effect on oral hygiene status, the difference between the highest PI and the GI was also significant. So, the significant difference in the lowest PI between two groups is not clinically significant.

In this study, the relationship between the handedness and PI has also been investigated in each quadrant separately. Because the past studies generally have evaluated total PI, GI, and other indices in right- and left-handed individuals and they were performed on adults, there is no possibility of accurate comparison with previous studies. But the results of several studies are consistent with the obtained results of this research. These studies have also not showed a significant difference between the handedness and the status of oral hygiene.[6] However, it has been noted by Kadkhodazadeh and Khodadustan[17] that there is no difference in the PI and GI between right-handed and left-handed individuals, but left-handed subjects have better and more access to the right side of the mouth to perform oral hygiene, while this issue is vice versa about right-handed individuals. Other different studies have also stated that left-handed individuals have better oral hygiene.[18] Furthermore, Cicek et al.[6] have shown that the PI and tongue coating index of the left-handed individuals are higher than the right-handed ones. The results of Tezel et al.'s[19] study are also in agreement with Cicek et al.'s.[6] They stated the rate of periodontitis in the left-handed adults is more in their study. Cicek et al.[6] also reported that the amount of sulfurous compounds which result in oral malodor is less in the left-handed people. It seems that the results of Kadkhodazadeh and Khodadustan,[17] Cicek et al.,[6] and Tezel et al.'s[19] study all confirm each other. It can be explained such that left-handed individuals perform better oral hygiene, and therefore they have less oral malodor and more gingival recession (due to powered and aggressive tooth brushing).

In contrast, some other researchers such as Cakur et al.[20] believe that right-handed individuals have better oral hygiene and less dental caries. Therefore, there are controversies in this domain. The differences in the results of different studies confirm that many factors can affect the ability of having good oral hygiene and less dental caries. Different ages of the investigated subjects, different individual chewing habits and different preferred side for chewing, different amount and concentration of saliva, socioeconomic, and cultural status, the nutritional patterns, diet, method, and time of brushing, using additional techniques for maintaining oral hygiene, and so on are all factors that affect GI and PI and the amount of the caries.[20] Even if the subjects could be selected similar as much as possible, inevitably, there are high individual differences that can influence results. The subjects of this study were all at the age range of 6–10 years and were selected from one region in Tehran to have similar socioeconomic and cultural status as possible. Although some studies show significant difference in the prevalence of dental caries and the level of oral hygiene in the right- and left-handed individuals, this was not observed in our research between two groups. However, in terms of the numerical difference, in general, the oral hygiene status, that is, GI and PI, was better in the left-handed individuals in our study. While exact numerical values of DMFT and dmft were very close together. It is clear that decay is a time-consuming process and occurs in long-term. So the procedure of present decay was started since a long time ago when the children were not yet able to brush their teeth alone and this was carried out by their parents. Therefore, in fact children handedness has not showed its net effect on the rate of caries yet. In addition, the position of the parents during brushing children's teeth and handedness of parents are also effective on this issue. But GI and PI are two indices which tell the status of oral hygiene is also effective on them in the short-term. So the differences in PI and GI of the right-handed and left-handed children (i.e., better oral hygiene status of the left-handed individuals) can be influenced by their different skill and ability to perform good oral hygiene. But this difference is not statistically significant. Because other factors are influencing children's oral hygiene status and they are still being monitored by their parents directly and indirectly.

According to the obtained results of this study and comparison with the conducted studies, a strong relationship cannot be considered between children handedness at the ages of 6–10 years and the oral hygiene status and their caries because many factors along with handedness are impressive on them at these ages.

In conclusion, the obtained results of this study showed that a relationship cannot be considered between the handedness and children's oral hygiene status. It is suggested to do more extensive studies to investigate this relationship on children who all are kept at a center such as the Welfare. This can be helpful because subjects of these centers may have more similarities with the environmental factors. For example, surely they all brush their teeth themselves or a coach with a single method has the responsibility of their oral hygiene and their diet pattern is also similar, considering the investigated age group has a high importance in the comparison of results.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Tables

  [Table 1], [Table 2], [Table 3]



 

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