ORIGINAL RESEARCH |
https://doi.org/10.5005/jp-journals-10015-2432 |
Mutans Streptococci and Oral Health Behavior in Children and Adolescents Having Primary and Permanent Caries: A Case–Control Study
1,3,4Department of Microbiology, Dr Harvansh Singh Judge Institute of Dental Sciences and Hospital, Panjab University, Chandigarh, India
2Department of Pedodontics, Dr Harvansh Singh Judge Institute of Dental Sciences and Hospital, Panjab University, Chandigarh, India
Corresponding Author: Sonia Bhonchal Bhardwaj, Department of Microbiology, Dr Harvansh Singh Judge Institute of Dental Sciences and Hospital, Panjab University, Chandigarh, India, Phone: +91 9872523838, e-mail: sbbhardwaj2002@yahoo.com
Received on: 03 May 2024; Accepted on: 04 June 2024; Published on: 28 June 2024
ABSTRACT
Aim: This case–control study aimed to evaluate the levels of mutans streptococci in primary caries in children and permanent caries in adolescents, with levels of mutans streptococci in caries-free children and adolescents in correlation with the decayed, missing, and filled permanent teeth (DMFT) scores. The oral health behavior of these groups was also studied.
Materials and methods: The sample size comprised 60 subjects—15 children having caries in primary dentition and 15 caries-free children in the age range of 2–5 years, 15 adolescents having caries in permanent dentition, and 15 caries-free adolescents in the age range of 12–15 years. The oral health behavior and dietary practices were recorded according to the World Health Organization (WHO) oral health questionnaire. The decayed, missing, and filled primary teeth (dmft)/DMFT index was calculated using WHO caries diagnostic criteria. Plaque samples were collected aseptically from the tooth sites, pooled, and inoculated on mitis salivarius agar (MSA). The total mutans streptococci count (CFU/mL) was then determined. The data were analyzed using paired t-tests and analysis of variance (ANOVA).
Results: Mutans streptococci in the caries group in children were 1.35 ± 1.99 CFU/mL. This was significantly higher (p < 0.01) compared to mutans streptococci in the caries group in adolescents, which was 0.8 ± 0.14 CFU/mL. The study shows high levels of mutans streptococci in the primary caries group with a high DMFT score correlating with increased sugar consumption and, to a lesser extent, with tooth brushing.
Conclusion: In the present study, it is observed that mutans streptococci are more predominant in caries of children than in the caries of adolescents.
Clinical significance: Caries research has focused largely on mutans streptococci as the main etiological pathogen of dental caries, but its impact on different stages of dentition has not been fully understood. Caries susceptibility associated with mutans streptococci is significantly high in the primary dentition stage. Therefore, the acquisition/transmission of mutans streptococci to prevent caries should be targeted in childhood.
How to cite this article: Bhardwaj SB, Sharma U, Mehta M, et al. Mutans Streptococci and Oral Health Behavior in Children and Adolescents Having Primary and Permanent Caries: A Case–Control Study. World J Dent 2024;15(5):406-410.
Source of support: Nil
Conflict of interest: None
Keywords: Caries, Oral health, Primary teeth, Permanent teeth, Streptococcus mutans.
INTRODUCTION
Dental caries is one of the most common chronic oral infectious diseases in the world.1 Streptococcus mutans has been implicated as the major etiological agent of dental caries.2,3 The ecological plaque hypothesis states that caries result from a shift in the balance of commensal flora to acid-producing bacteria, including S. mutans, due to changes in the oral cavity environment, resulting in biofilm accumulation on the dental surface.4 Mainly, studies have reported a correlation between levels of mutans streptococci and the severity of dental caries, but a few studies have also reported a lack of correlation.3,5 Mutans streptococci are acidogens, using glucosyltransferases to metabolize sucrose, thereby increasing bacterial adhesion and biofilm accumulation on the dental surface.6 The colonization of mutans streptococci is increased with increased sugar consumption, as it decreases the pH and promotes cariogenic flora.7 Tooth brushing also modulates the level of mutans streptococci.8 Poor oral hygiene practices can be a risk factor for caries in children as well as adolescents.
Considerable research has established that S. mutans is an efficient cariogenic microorganism. Recent research has shown a significant shift in oral microbiome composition from the primary to permanent dentition stage, indicating several transitions between primary and permanent dentition stages. This suggests a strong correlation between caries experience in primary teeth and caries outcome in permanent teeth.9 Many studies have investigated the correlation of oral microbiota and caries in different dentition stages using saliva as a sample.10,11 However, the tooth surface is the natural habitat for dental plaque.12,13 The levels of S. mutans in different dentition stages have not been fully explored, particularly using dental plaque samples. Recent techniques like 16S ribosomal RNA sequencing provide adequate phylogenetic information for the identification of bacteria but cannot identify some bacteria at the species level, including streptococci species.9 The present study identified and analyzed colony-forming units (CFUs) of S. mutans by culture technique, considering its simplicity. The relationship between mutans streptococci, sugar intake, tooth brushing, and caries in children compared to adolescents has been largely ignored.
In this case–control study, we evaluated the levels of mutans streptococci in primary caries in children and permanent caries in adolescents, comparing these with levels of mutans streptococci in caries-free children and adolescents and the decayed, missing, and filled permanent teeth (DMFT) scores with respect to oral health behavior.
MATERIALS AND METHODS
The study was conducted from January to October 2023 in the Department of Microbiology at Dr Harvansh Singh Judge Institute of Dental Sciences and Hospital, Panjab University, Chandigarh, India. Ethical clearance was obtained from the Institutional Ethics Committee (PUIEC/2018/119/A-1/29/10), and informed consent and assent were taken from the subjects/parents for inclusion in the study. The subjects underwent a dental examination for caries by a well-trained pediatric dentist according to the criteria recommended by the World Health Organization (WHO) 2013, in the pediatric dental unit of Dr Harvansh Singh Judge Institute of Dental Sciences and Hospital, Panjab University, Chandigarh, India. The dental examination was performed using a plain dental mirror and an explorer under artificial light.
Recruitment and Sampling
The total sample size consisted of 60 subjects. The subjects with caries and age-matched caries-free controls were put into two different groups—(1) 15 subjects with caries in primary dentition and 15 caries-free age-matched controls (age 2–5 years), and (2) 15 subjects with caries in permanent dentition and 15 caries-free age-matched controls (age 12–15 years). Subjects who had taken antibiotics 3 months prior to plaque sampling, had systemic disease, or were undergoing orthodontic treatment were excluded.
The DMFT value was calculated following WHO’s caries diagnostic criteria.14 The prevalence and severity of dental caries were assessed and recorded using the decayed, missing, and filled primary teeth (dmft)/DMFT index (decayed, missing, and filled teeth). The oral health behavior was assessed as per the WHO oral health questionnaire.14 The dental plaque collection was standardized, and all the subjects were asked to refrain from any oral hygiene activity, eating, and drinking in the morning before oral sampling. Plaque samples were derived from the same tooth site in all four quadrants and pooled. The collected samples were put into sterile transport media (thioglycollate broth, HiMedia) and immediately transferred to the microbiology laboratory. A volume of 0.1 mL of the sample was spread on mitis salivarius agar (MSA), HiMedia, Mumbai, in duplicate and incubated at 37°C for 48 hours in a 5% carbon dioxide enriched atmosphere. Colonies on MSA having morphological characteristics of S. mutans (0.5 mm raised convex undulated colonies of light blue color with rough margins) were identified, visualized by Gram staining (gram-positive cocci in chains), and counted under a colony counter. The results were expressed as CFU/mL.15
Statistical Analysis
The statistical analysis was done using Statistical Package for the Social Sciences software (version 22, IBM Corp., Armonk, United States of America). The t-test was used to verify statistical differences in the parameters of sugar consumption and oral habits. Analysis of variance (ANOVA) was performed for the categories of S. mutans variables and their influence on DMFT scores.
RESULTS
In this case–control study, subjects were divided according to their age and type of dentition. The subjects with caries and age-matched caries-free controls were put into two different groups—subjects with caries in primary dentition and caries-free age-matched controls (age 2–5 years) and subjects with caries in permanent dentition and caries-free age-matched controls (age 12–15 years). The gender distribution of the subjects was 29 females and 31 males.
Oral Hygiene Practices
Adequate tooth cleaning was performed by all the subjects in the primary and permanent control groups, whereas in subjects with caries, the frequency of tooth cleaning was only 6.7% (Table 1). Tooth cleaning frequency showed a significant difference in controls compared to subjects with caries in primary and permanent dentition (p < 0.001). However, almost all the subjects (98.3%) brushed their teeth using toothpaste irrespective of age and sex.
Parameter | Primary caries group (%) | Permanent caries group (%) | Primary control group (%) | Permanent control group (%) | p-value |
---|---|---|---|---|---|
Tooth cleaning frequency | |||||
≥2 times/day | 6.7 | 6.7 | 100 | 100 | <0.001 |
<2 times/day | 93.3 | 93.3 | 0 | 0 | |
Dental visits | |||||
Regular ≤6 months | 6.7 | 20 | 100 | 100 | <0.001 |
Irregular >6 months | 93.3 | 80 | 0 | 0 | |
Dietary practices | |||||
Fruits and raw vegetables | |||||
≥2 times/day | 26.7 | 20 | 100 | 100 | <0.001 |
<2 times/day | 73.3 | 80 | 0 | 0 | |
Sugary foods | |||||
≥2 times/day | 93.3 | 60 | 0 | 0 | <0.001 |
<2 times/day | 6.7 | 40 | 100 | 100 | |
Chewing sugared gum | |||||
≥2 times/day | 13.33 | 20 | 20 | 13.33 | 0.670 |
Irregular and never | 86.67 | 80 | 80 | 86.67 |
Dental Visits
Regular dental visits were observed in the subjects of both control groups, whereas only 6.7% of those with primary caries and 20% of those with permanent caries visited the dentist (Table 1). The reasons for the last visit to the dentist were pain in teeth/gums/mouth or routine checkup of teeth/treatment/follow-up, irrespective of age and sex.
Dietary Practices
Fruit and Sugary Foods
Fruit was consumed twice a day or more by the control subjects of both primary and permanent dentition groups. This was significantly different (p < 0.001) in the test groups of primary and permanent dentition caries (Table 1). The frequency and quantity of consumption of sugary foods (biscuits, cakes, cream cakes, lemonade, soft drinks, sweets, candy, jam, milk/coffee/tea with sugar) was more than twice a day in the test groups of primary and permanent dentition with caries. There was also a significant difference in sugar consumption between the primary and permanent caries test groups.
Chewing Sugared Gum
Chewing sugared gum twice daily or more was observed more frequently in children compared to adolescents. However, no significant difference was observed regarding chewing gum practices between the groups (Table 1).
Caries Experience and S. mutans in Different Types of Dentition
In subjects having caries in the primary dentition, the mutans streptococci count of the pooled plaque sample was 1.35 ± 1.99 CFU/mL with a mean dmft score of 8.60 ± 3.58. In the subjects having caries in the permanent dentition, the mutans streptococci count of the pooled plaque sample was 0.8 ± 0.14 CFU/mL with a mean dmft score of 3.67 ± 3.15 (Table 2).
Parameter | Primary caries group [mean ± standard deviation (SD)] | Permanent caries group (mean ± SD) | Primary control group (mean ± SD) | Permanent control group (mean ± SD) | p-value |
---|---|---|---|---|---|
Mutans streptococci* (CFU/mL) | 1.35 ± 1.99 | 0.8 ± 0.14 | 0.06 ± 0.03 | 0.02 ± 0.01 | <0.01 |
DMFT | 8.60 ± 3.58 | 3.67 ± 3.15 | 0 | 0 | <0.01 |
*, To be multiplied by 105
Mutans streptococci are more predominant in the caries of children than in the caries of adolescents. Caries susceptibility due to mutans streptococci depends on the dentition stage and is influenced by dietary factors such as the consumption of sugar, fruits, and raw vegetables. The levels of mutans streptococci are also associated with tooth cleaning frequency in both children and adolescents.
DISCUSSION
Analysis of oral hygiene practices shows that regular dental visits and tooth cleaning are related to better oral healthcare. Inadequate oral hygiene practices contribute to caries in both the primary and permanent dentition groups. The WHO Global Health Index indicates that by 12 years of age, all permanent teeth have erupted except third molars. A frequency of brushing teeth with toothpaste more than two times a day was associated with a lower caries score in both groups. Studies have shown lower DMFT scores in 3–5-year-old children with an early start of tooth brushing and a higher frequency of tooth brushing.16,17 Hoceini et al. have observed lower DMFT scores in association with tooth brushing frequency in adults too.18
Similarly, children and adolescents who consumed fruit more frequently had a lower incidence of caries. The regular consumption of fruits provides secretory immunoglobulin A (IgA) as the first line of defense and inhibits the formation of biofilm.19 Moreover, increased salivary secretions help in mechanical cleansing, removing food debris, and providing phytochemicals and vitamins, preventing the incidence of caries. The consumption of sugary foods was higher in the younger age-group. The consumption of sugar is directly related to plaque formation and the adhesion of mutans streptococci.20
The plaque formation results in increased production of lipoteichoic acid, leading to enhanced adhesion to the tooth surface by mutans streptococci in the presence of sugars.21 Initially, caries was related to the consumption of dietary carbohydrates, but with the introduction of processed sugars in their most cariogenic form, the progression of caries has increased. These factors could be related to the increased presence of levels of mutans streptococci in children with caries in the primary dentition. In a study by Vachiraojpisan et al., it was observed that in children aged 6–19 months, a higher count of salivary S. mutans was a significant predictor of early childhood caries.22 The plaque index was also significantly high in the caries group compared to caries-free group.
Chewing sugared gum showed no significant difference in primary and permanent caries groups, even when it was chewed more than two times a day. This is in accordance with other studies suggesting that chewing gum reduces salivary debris and dental plaque.23 Tangade et al. further observed chewing sugar-free gum and sugared gum was not beneficial in plaque deposition in both groups.24
Mitis salivarius agar is an excellent, highly effective, and selective medium for the isolation of S. mutans. A higher recovery of S. mutans (39.5%) has been reported from MSA compared to conventional media such as blood agar (24.07%).25 The CFU of S. mutans was directly related to the caries score, particularly in the primary caries group. There was a significant decline in the levels of mutans streptococci in relation to caries in adolescents. This shows that species such as S. mutans are more dominant in childhood caries compared to caries in adolescents. The profile of S. mutans changes with the progression of the disease and differs between primary and permanent dentition. This is in accordance with the few studies available.5,9 The members of the Streptococcus colonize early and are predominant in the dental plaque of primary dentition, whereas as the dentition matures, the late colonizers from other genera predominate in the permanent dentition. Mutans streptococci were also observed in healthy children and adolescents, though the counts were very low. It could be concluded that the presence of acidogens like mutans streptococci in healthy children and adolescents at a level of 1–2% or less does not lead to the development of caries, as mutans streptococci levels at carious sites within this range do not significantly impact the local pH.26 In a recent study, 25% of caries-active children did not harbor mutans streptococci, while 42% of caries-free children did have mutans streptococci levels above the cutoff, highlighting the role of nonmutans streptococci species in causing dental caries.27 Current literature supports a polymicrobial etiology of dental caries, with many bacteria such as Actinomyces and Prevotella playing important roles in the development and progression of dental caries along with S. mutans.28
The study shows high DMFT scores in children with high levels of mutans streptococci. This group also consumed more sugar. The consumption of sugar more frequently played a greater role in the development of childhood caries compared to oral health practices. There is a strong correlation between mutans streptococci and individuals consuming a cariogenic diet who have poor oral hygiene practices. The small sample size and the need to evaluate the levels of other oral bacteria are limitations of the present study.
FUTURE DIRECTIONS OF THE STUDY
Caries prevention strategies such as caries vaccines, probiotics, prebiotics, and treatment with silver compounds need to be developed and targeted at an early age/childhood to reverse the imbalance of mutans streptococci and prevent its acquisition/transmission.
CONCLUSION
In the present study, it is observed that mutans streptococci are more predominant in the caries of children than in the caries of adolescents, in whom nonmutans streptococci are more predominant. Caries is a multifactorial disease with mutans streptococci and the frequency of sugar consumption playing important roles in the development of childhood caries. Encouragement for good oral hygiene and dietary practices is essential. It is crucial to continue efforts in the development of a mutans streptococci caries vaccine, which has declined over the years, considering the role of mutans streptococci in caries development, progression, and pathogenicity.
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