Posted at the Institutional Resources for Unique Collection and Academic Archives at Tokyo Dental College, Available from http://ir.tdc.ac.jp/
Title Relationship between Interdental Spacing and Colonization by Streptococcus mutans in Children
Author(s) Yonezu, T; Shintani, S
Journal Bulletin of Tokyo Dental College, 58(2): 111‑116 URL http://hdl.handle.net/10130/5895
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Relationship between Interdental Spacing and Colonization by Streptococcus mutans in Children
Takuro Yonezu1) and Seikou Shintani2)
1) Department of Pediatric Dentistry, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan
2) Department of Pediatric Dentistry, Tokyo Dental College, 2-9-18 Misaki-cho, Chiyoda-ku, Tokyo 101-0061, Japan
Received 13 January, 2016/Accepted for publication 30 August, 2016
Abstract
The purpose of this study was to investigate the relationship between interdental spacing in the upper incisors and other associated factors with colonization by Streptococcus mutans in children. A total of 47 children aged between 24 and 36 months with no decayed cavities were enrolled in the study. Models were obtained to evaluate interdental spacing in the upper anterior region. The relationships between S. mutans colonization and num- ber of erupted teeth, interdental spacing, diet, and oral hygiene behavior were investi- gated. S. mutans was detected in the saliva of 14 children (29.8%). No sociodemographic variable was associated with colonization by S. mutans. Neither number of erupted teeth nor children’s age showed an influence on colonization by S. mutans. However, children with interdental spacing in the upper incisors were less likely to show colonization by S.
mutans (15.8%) than those without (39.3%). Furthermore, children who ceased breast- and/or bottle-feeding by 15 months of age were less likely to show colonization by S.
mutans (22.7%) than those who continued feeding until 19 months of age or more (46.2%).
Key words: Colonization — S. mutans — Interdental spacing — Young children
Introduction
Streptococcus mutans and Streptococcus sobri- nus are the principal bacteria responsible for dental caries in humans12,13). A number of fac- tors in the oral environment have been reported to show a correlation with coloniza- tion by S. mutans, including diet14,17), salivary composition4,6), enamel hypoplasia9,11), erup- tion of teeth5,7,15) and oral hygiene14,16). Tradi-
tionally, colonization of the oral cavity by S. mutans is believed to only occur when teeth are present. According to Gibbons and Houte8), this microorganism requires a non- shedding epithelial surface for colonization, so such activity will only after eruption of the primary teeth. Furthermore, Caufield et al.5) posited that if colonization by S. mutans occurs with tooth emergence, then specific windows of infectivity might exist, and that these might 111
coincide with the eruption of the primary incisors and primary molars. Fujiwara et al.7) also reported that the salivary concentrations of S. mutans correlated significantly with the number of erupted teeth, and that a large increment was observed with eruption of the primary second molars. Other investigators also reported similarly high levels in 24-month- old children10,17). This suggests that, pits and fissures are more readily colonized by S.
mutans than smooth surfaces.
However, Milgrom et al.14) reported a preva- lence of 53% of S. mutans infection in chil- dren aged 6 to 12 months. Some recent stud- ies have shown that abnormalities in hard tis- sue surfaces can also modulate adherence and colonization by S. mutans 9,11). These find- ings indicate that the loss of integrity incurred by enamel hypoplasia compromises the regu- larity of the tooth surface, thus enhancing colonization by S. mutans due to an increase in bacterial adherence and plaque retention.
Here, we hypothesized that an absence interdental spacing in the upper anterior region would also modulate adherence and colonization of S. mutans in children.
The purpose of this study was to investigate the relationship between interdental spacing in the upper primary incisors and other asso- ciated factors with colonization by S. mutans in children.
Materials and Methods 1. Study setting and participants
The present study was conducted at the Minami-Urawa Techno Center (Combi Cor- poration). Children aged 24–36 months were
recruited by monitors at the Combi Corpora- tion, based on the following criteria:
1) Completion of a questionnaire by the parent or guardian regarding the child’s oral hygiene habits and dental, social, and feeding histories.
2) Informed parental/guardian consent for the child’s participation.
3) Good general health and age-appropri- ate cognitive development.
4) No history of recent antibiotic use.
A total of 47 children were enrolled in the study.
All the study procedures were undertaken after obtaining written informed consent from the child’s parents/guardian. The pro- tocol of this study was approved by the Ethics Committee of Tokyo Dental College (approval no. 277).
2. Experimental design
The children were examined for caries with a mirror and explorer under natural light.
Models were then obtained to evaluate inter- dental spacing in the upper anterior region.
An unstimulated saliva specimen was col- lected from each child with a sterile spongy tip (Fig. 1). A sterile, disposable syringe was then used to extract the saliva sample from the spongy tip. The saliva samples were then immediately transferred to a laboratory (GC Oral Check Center, Tokyo) for quantitative detection of total bacteria and S. mutans in saliva by real-time PCR.
3. Statistical analysis
Non-parametric statistical analyses were performed with the Chi-square and Fisher’s exact test. Logistic regression models were
【版面】W：396 pt（片段 192 pt） H：588 pt 【本文】行数不明（手組み） 10pt 12pt 送り
【図】●図番号・タイトル・説明：11.3Q 12.7H New Baskerville ITC Std 図タイトルと説明のアキ 9Q ●タイトル折り返し：番号の後（続 く説明の先頭は字下げ不要） ●図説の幅 片段：片段固定 全段：図幅
【表】●番号・タイトル・説明：11.3Q 12.7H New Baskerville ITC Std タイトルと表のアキ 10.5Q ●罫線 表はじめのみ双罫 表中の 罫の太さ 1.411mm ●表中：11.3Q 12.7H New Baskerville ITC Std ●脚注 11.3Q 12.7H New Baskerville ITC Std 字下げなし 斜体は New Baskerville ITC Std Italic（タグは <l>） 半角ダーシは -（ハイフン）に F50：tohaba の文字スタイルをかけて作成
Fig. 1 Collection of saliva samples Yonezu T and Shintani S 112
also used to determine independent predic- tors for S. mutans colonization. SAS ver.8.02 software was used for the analysis.
Results
No decayed cavities were observed in any of the children. Colonization as indicated by the presence of S. mutans in the saliva was
observed in 14 children (29.8%).
Table 1 shows the relationship between demographic factors, oral hygiene, dietary habits, and detection of S. mutans. Table 2 shows which factors were identified as show- ing a correlation with colonization by S. mutans in the logistic regression model.
No sociodemographic variables showed an association with the colonization by S. mutans.
Neither number of erupted teeth nor age
Table 1 Relationship between microbial levels and general, feeding, and oral health risk factors
Possible risk factors
Children in whom
S. mutans detected n x2 p-value
n %
Age (months)
30- 6 25.0 24
0.29 0.59
24-29 8 34.8 23
Number of erupted teeth
20 8 32.0 25
1.63 0.44
18 1 10.0 10
16 5 41.7 12
Interdental space
Yes 3 15.8 19
0.96 0.33
No 11 39.3 28
Feeding practice
Breast 9 28.1 32
0.00 0.79
Bottle and Mix 5 33.3 15
Duration of feeding
19 months or more 6 46.2 13
1.17 0.56
16-18 months 3 25.0 12
Less than 15 months 5 22.7 22
Dental caries in mother
Yes 5 29.4 17
0.00 0.96
No 9 30.0 30
Brushing by mother
Yes 9 30.0 30
0.00 0.98
No 5 29.4 17
Fluoride dentifrice use
Yes 2 22.2 9
0.00 0.98
No 12 31.6 38
Xylitol tablet use
Yes 3 18.8 16
0.32 0.57
No 11 35.5 31
showed an influence on colonization by S. mutans. However, children with interdental spacing in the upper incisors were less likely to show colonization by S. mutans (15.8%) than those without (39.3%). Furthermore, children who ceased breast- and/or bottle- feeding by 15 months of age were less likely to show colonization by S. mutans (22.7%) than those who continued feeding until 19 months of age or more (46.2%).
Discussion
Traditionally, specific anatomical charac- teristics of the enamel surface are believed to facilitate the colonization by mutans strepto- cocci, and the type and number of present teeth are correlated with its initial acquisi- tion8). The initial infection usually coincides with the emergence of the molar teeth. This suggests that the morphology of the tooth surfaces such as the presence of pits and fis- sures plays an important role in colonization of mutans streptococci 5,7).
The results of the present study showed that neither number of erupted teeth nor children’s age had an influence on coloniza- tion by S. mutans. The results did reveal a dif- ference depending on the presence or absence of interdental spaces, however, and while this disparity was not statistically signifi- cant, it dose suggest that the finding that chil-
dren without interdental spaces in the upper anterior region were more readily colonized by S. mutans cannot be ignored. This suggests that a tight interdental area enhances coloni- zation by S. mutans on the tooth surface due to increased bacterial adherence and plaque retention together with a decrease in carbohy- drate clearance.
Warren et al.18) reported a weak association between the absence of interdental spaces and greater decay experience in the primary dentition. Ben-Basset et al.1) also studied the relationship between interdental spacing and caries, and reported that caries-free children had a significantly higher proportion of sur- faces with at least 0.5 mm of space adjacent to them compared to the caries-affected group.
Furthermore, children who ceased breast- and/or bottle-feeding by 15 months of age were less likely to show colonization by S. mutans (22.7%) than those who continued feeding until 19 months of age or more (46.2%).
Human breast milk is generally thought to be minimally cariogenic based on the results of in vitro study3). On the other hand, a recent animal study2) has suggested that high fre- quency exposure to human breast milk is more cariogenic than that to bovine milk, probably because human breast milk contains a higher concentration of lactose. The results of an earlier study by our group21) showed that children who continued to breastfeed at the
【版面】W：396 pt（片段 192 pt） H：588 pt 【本文】行数不明（手組み） 10pt 12pt 送り
【図】●図番号・タイトル・説明：11.3Q 12.7H New Baskerville ITC Std 図タイトルと説明のアキ 9Q ●タイトル折り返し：番号の後（続 く説明の先頭は字下げ不要） ●図説の幅 片段：片段固定 全段：図幅
【表】●番号・タイトル・説明：11.3Q 12.7H New Baskerville ITC Std タイトルと表のアキ 10.5Q ●罫線 表はじめのみ双罫 表中の 罫の太さ 1.411mm ●表中：11.3Q 12.7H New Baskerville ITC Std ●脚注 11.3Q 12.7H New Baskerville ITC Std 字下げなし 斜体は New Baskerville ITC Std Italic（タグは <l>） 半角ダーシは -（ハイフン）に F50：tohaba の文字スタイルをかけて作成
Table 2 Logistic analysis for acquisition of S. mutans with general, feed- ing and oral health risk factor
p-value Odds ratio 95%CI
Age (months) 0.924 1.09 0.18-6.42
Number of erupted teeth 0.807 0.88 0.32-2.43
lnterdental space 0.077 4.57 0.85-24.61
Feeding practice (method) 0.317 0.34 0.04-2.81
Duration of feeding 0.119 2.32 0.81-6.66
Mother’s dental caries status 0.970 1.03 0.19-5.57
Brushing by mother 0.520 1.87 0.28-12.47
Fluoride dentifrice use 0.334 0.30 0.03-3.51
Xylitol tablet use 0.884 0.87 0.14-5.59
Yonezu T and Shintani S 114
prolonged breastfeeding is a risk factor for caries in early childhood.
Clinical studies have shown that caries risk is correlated with age at which initial S. mutans colonization occurs14). Earlier study by our group found that children who developed caries before 18 months of age exhibited high caries progression up to 3 years of age19,20). In addition, maxillary primary incisors, espe- cially proximal surfaces were most frequently affected by caries in Japanese children aged between 2 and 3 years19,20). Therefore, any strategy for the prevention of dental caries should include timely control of colonization of the oral cavity by cariogenic bacteria in young children. The present study supports the suggestion that special preventive dental care programs should be developed for chil- dren under 18 months of age. These finding might be relevant in the institution of preven- tive strategies for early childhood caries.
Conflict of Interest
The authors declare no potential conflicts with respect to the authorship and/or publi- cation of this article.
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Correspondence:
Dr. Takuro Yonezu
Department of Pediatric Dentistry, Tokyo Dental College,
1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan E-mail: [email protected] Yonezu T and Shintani S
116
