|Year : 2013 | Volume
| Issue : 2 | Page : 130-133
Evaluation of microflora of root carious lesions in different age groups: A microbiological study
Ashok Aparna1, Mithra N Hegde1, Veena Shetty2
1 Department of Conservative Dentistry and Endodontics, A. B. Shetty Memorial Institute of Dental Sciences, Deralakatte, Mangalore, Karnata, India
2 Department of Microbiology, K.S. Hegde Medical Academy, Nitte University, Deralakatte, Mangalore, Karnataka, India
|Date of Web Publication||21-May-2013|
Department of Conservative Dentistry and Endodontics, A.B. Shetty Memorial Institute of Dental Sciences, Nitte University, Deralakatte, Mangalore - 575 018, Karnataka
Source of Support: None, Conflict of Interest: None
Aim: To evaluate the prevalence of mutans streptococci, lactobacilli and Actinomyces species in root carious lesions in middle-aged and older adults of South Indian population and to comparatively evaluate the microbial count in two different age groups. Materials and Methods: Specimens of root carious lesions were collected from 60 adults for bacteriological studies. Amongst which 28 subjects belonged to middle age group (35-44 years) and 32 subjects to older age group (55-75 years). Standard procedures of culture, isolation and identification of aerobic and anaerobic bacteria were adopted in the study. Results: The analysis of results was performed using Chi-square test. SPSS 20 has been used to analyze the data. Among the isolated microorganisms, streptococci (56.7%) and lactobacilli (28.3%) were more prevalent in root caries lesions compared to actinomyces species (15.0%) and most frequently occurred in older adults. There is also a statistically significant association between the age group and the presence of lactobacillus (P=0.024). Conclusions: Aerobic Gram-positive cocci (Streptococcus mutans, lactobacillus) as well as anaerobic bacteria (Actinomyces spp.), occurred most frequently in root carious lesions in older adults as compared to middle-aged population.
Keywords: Actinomyces spp, aerobic/anaerobic bacteria, lactobacilli, root caries, streptococcus mutans
|How to cite this article:|
Aparna A, Hegde MN, Shetty V. Evaluation of microflora of root carious lesions in different age groups: A microbiological study. Eur J Gen Dent 2013;2:130-3
|How to cite this URL:|
Aparna A, Hegde MN, Shetty V. Evaluation of microflora of root carious lesions in different age groups: A microbiological study. Eur J Gen Dent [serial online] 2013 [cited 2019 Jul 19];2:130-3. Available from: http://www.ejgd.org/text.asp?2013/2/2/130/112310
| Introduction|| |
Root caries is an important dental disease, especially since the number of elderly dentate people in institutions is increasing. , Root surface caries, as the name implies, occurs on root cementum or dentine and is caused by a microbial biofilm. The disease is secondary to gingival recession, since in a healthy mouth, cementum and dentine are not exposed to the microflora and therefore, are not prone to colonization. ,,
The aetiology of root caries is multifactorial of which microbiological factor plays a critical role. ,, While there is ample evidence to imply a strong association between mutans group streptococci and coronal caries, ,,,, similar data on microbiological agents in root caries is poorly understood.
Historically, mutans streptococci and lactobacilli have been associated with the initiation and progression of root caries. Despite the significantly raised levels of mutans streptococci, there is no reliable evidence that they initiate or cause the progression of root lesions, either on their own or even in concert with other bacteria.  Some epidemiological studies have shown that Actinomyces spp. are predominant bacteria in root caries, ,,,,, while others have demonstrated a variety of bacteria and failed to implicate any single bacterial genus as a predominant isolate. ,,
A cross sectional study conducted in the South Canara District of Karnataka in the year 2007-2008 has revealed that root surface caries was more prevalent in males, in the age group of 51-65 as compared to the age group of 31-51 and has been positively associated with age.  However, the information that is available on the nature of the microflora associated with root surface lesions is in some instances superficial.  There are no statistical data of any microbiological study on root carious lesions on the South Indian population. Hence, there is a need to identify the micro-organisms involved in the cause and progression of root caries for its prevention and management.
This study evaluated whether the prevalence of various micro-organisms were dependant on the age of the individuals. Its aims were to evaluate the prevalence of mutans streptococci, lactobacilli and Actinomyces species in root carious lesions in middle-aged and older adults of South Indian population and to compare the microbial prevalence in adults in 2 different age groups.
| Materials and Methods|| |
This study was conducted in the University, after the approval from institutional ethical committee.
Twelve thousand and five hundred healthy adult patients under the age group of 35-75 years had reported at the OPD between December 2011-June 2012.Out of these, only 60 patients fulfilling the inclusion and exclusion criteria were reported.
- Healthy adults with no history of medications, systemic illness and radiotherapy
- Soft, active root carious lesions.
Samples of infected dentin were collected from these 60 subjects by a single examiner. Among them, 60 adults were classified into middle-aged group (35-44 years) with 28 subjects and older group (55-75 years) with 32 subjects. After the removal of infected dentin, the teeth were restored and patients were given instructions about tooth brushing techniques and oral hygiene aids and were later recalled for follow up of maintenance.
- Teeth with restorations
- Teeth undergoing non-invasive treatment strategies.
Instruments used in the study were sterile stainless steel mouth mirror, spoon excavator, sample tubes, petri plates.
Carious dentin was sampled from individual soft root caries lesions. To minimize contamination of the underlying infected dentin with superficial plaque, which has a different microbial composition, the plaque overlying the lesion was removed using a toothbrush and sterile water. The infected dentin was sampled by means of a sterile excavator passing through the vertical dimension of the lesion, from the gingival margin. Each sample was placed into 2 ml of Thioglycollate medium (Hi Media, Mumbai, India).
Microbial analysis of samples
Using conventional plating methods, each sample was processed within 3 hours to determine the prevalence of Streptococci, Lactobacilli and Actinomyces species. Mitis Salivarius Agar, Lactobacillus MRS Agar and Actinomyces Agar (Hi Media, Mumbai, India) were used to culture Streptococci, Lactobacilli and Actinomyces species respectively.
A Chi-square test was conducted to understand how the oral flora varies with aging population. SPSS 20 has been used to analyze the data. Due to categorical nature of observed data, non- parametric test, Chi-square test has been used to analyze the significant differences in the microflora of root caries patients as a function of age.
| Results|| |
[Table 1] shows that Streptococcus mutans were present in 34 (56.7% of the total) samples. Specifically, 13 samples (38.2%) in the age group of 35-44 years identified the presence of Streptococcus mutans and 21 samples (61.8%) found its existence in the age group of 55-75 years. The Chi-square examines whether there is an association between the two categorical variables, age group and presence of the bacteria Streptococcus mutans in root caries patients. In this case, the P value is 0.134 [Table 2]. Hence, stating there is no significant difference in the presence of Streptococcus mutans among the age groups in root caries patients. [Table 1] also suggests that lactobacillus was present in 17 (28.3% of the total) cases. Among these, lactobacillus was present in four samples (23.5%) in the age group of 35-44 years and in 13 samples (76.5%) in the age group of 55-75 years. In this case, the P value is 0.024 [Table 2], thus stating there is a significant difference in the presence of lactobacillus among the age groups in root caries patients.
|Table 1: Comparison of the prevalence of Streptococcus mutans, Lactobacillus and Actinomyces spp. in middle aged (35‑44 years) and older adults (55‑75 years)|
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Actinomyces spp. was present in 9 (15.0% of the total) samples [Table 1]. Specifically, in the age group of 35-44, Actinomyces spp. was present in 2 samples (22.2%) and in the age group of 55-75 years identified 7 samples (77.8%). In this case, the P value is 0.111 [Table 2]. Hence, stating there is no significant difference in the presence of Actinomyces spp. among the age groups in root caries patients.
The predominant microrganism isolated from 60 root carious lesions was Streptococcus mutans followed by Lactobacillus and Actinomyces spp and all the three microorganisms were predominant in older group (55-75 years) as compared to middle-aged group (35-44 years). Also, there is a significant association between the age group and the presence of Lactobacillus [Table 1] and [Figure 1].
|Figure 1: Comparison of prevalence of Streptococcus mutans, Lactobacillus and Actinomyces spp. in middle aged (35‑44 years) and older adults (55‑75 years)|
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| Discussion|| |
The present study offers the evaluation of the microflora associated with root surfaces in middle-aged and elderly subjects based on conventional plating methods. Among the 60 samples collected, 28 samples belonged to 35-44 years (middle age) and 32 samples to 55-75 years (older age).
The first studies of lesions of root surface caries in humans made by Sumney and Jordan identified S. mutans as a significant component of the flora. However, Actinomyces were also identified. This study stated that a unique bacterial flora exists for caries that originates on different surfaces of the dentition, emphasizing a unique flora from root surface caries lesions. 
The predominant microorganisms isolated by Shen et al.  from 30 root caries lesions were Lactobacillus spp. (90%), Streptococcus spp. (100%) and Actinomyces spp. (63%). This result of the present Chinese subject was in agreement with studies, most of which conducted on Caucasians subjects, at other parts of the world. ,
Study by Ellen et al., showed that root surfaces harboring Lactobacillus and S. mutans were at greater risk of becoming carious and that persons with both bacteria in their plaque were at higher risk of developing root surface caries. Although A. viscosus was commonly isolated, Ellen et al. could not detect differences between the isolation or numbers of this organism. 
However, it was known from the earlier studies of Jordan and Hammond that the flora was more complex and included 'intermediate' strains of Actinomyces.
In the present study, the predominant microrganism isolated was Streptococcus mutans followed by Lactobacillus and Actinomyces spp. which were also identified in few subjects. Among the 60 samples collected, Streptococcus mutans were identified in 34 (56.7% of the total) samples. Out of these, 13 (38.2%) samples belonged to 35-44 years (middle age) and 21 (61.8%) samples- to 55-75 years (older age). Lactobacillus was present in 17 (28.3% of the total) samples whereas Actinomyces spp. was identified in 9 (15.0% of the total) samples. Specifically, in the age group of 55-75 years, Lactobacillus was identified in 13 samples (76.5%) and Actinomyces spp. in 7 samples (77.8%). This suggests that Streptococcus mutans, Lactobacillus and Actinomyces spp were predominant in older group (55-75 years) as compared to middle-aged group (35-44 years). Also, there is a significant association between the age group and the presence of Lactobacillus.
Apparently, a stage has been reached in the analysis of the microbiology of plaque associated with root caries where workers are locked into the enumeration of a limited number of bacteria dictated by selective media. Yet there is considerable information on diversity among even those species that we accept as 'target' organisms, the 'mutans streptococci', oral Streptococcus, Actinomyces, and Lactobacillus. Consideration of this diversity in future studies may reveal other associations between bacteria and root surface caries. Recently, microarray analysis of the microflora of root caries also demonstrated that other species in addition to Streptococcus mutans, lactobacilli and Actinomyces may be also involved in the root caries process.
Given careful characterization of the flora and the state of the lesions, it is likely that microbiology will be useful in diagnosing the state of a root surface lesion and in determining the mode of treatment in control of the progression of root surface lesions. 
| Conclusion|| |
Streptococcus mutans , Lactobacillus and Actinomyces spp. were higher in older group (55-75 years) as compared to middle-aged group (35-44 years) of South Indian population with Streptococcus mutans being the highest in mumber followed by Lactobacillus and Actinomyces spp. respectively.Also, there is a significant association between the age group and the presence of Lactobacillus.
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[Table 1], [Table 2]