|Year : 2013 | Volume
| Issue : 1 | Page : 25-28
Oratest: A new concept to test caries activity
S Saxena1, Siddharth Pundir2, Jain Aena3
1 Professor & Head Department of Oral Pathology & Microbiology, Rungta Dental College, Bhilai, Chattisgarh, India
2 Senior Lecturer, Department of Oral Pathology & Microbiology, Rungta Dental College, Bhilai, Chattisgarh, India
3 Department of Periodontics, Rungta Dental College, Bhilai, Chattisgarh, India
|Date of Web Publication||27-May-2013|
House No: 8, Sector-11, Shastri Nagar, Meerut Uttar Pradesh - 250 004
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Caries activity tests are based on the concept of a specific odontogenic infection, the principle causative organism being streptococci mutans. Their predominance is attributed to its acidogenic and aciduric nature after a selective growth advantages over the other non- acid tolerant organisms. Many studies on caries activity are aimed at finding relevant microorganisms. Till date, the ideal method to evaluate in terms of sensitivity, specialization and reliability has not been found. Many of these caries activity tests require extensive work up time and additional equipment. Rosenberg et al. in 1989 developed Oratest, a simple, economical, non- invasive and less time-consuming test for estimating the oral microbial level. The test is simple and consists of rinsing the mouth with 10 ml of sterile milk, 3 ml of which is mixed with 0.12 ml of 0.1% methylene blue dye and observed for colour change. The present study sample consists of twenty five children with dental caries and twenty five controls, free of caries, gingivitis and other oral ailments. This study is being conducted in the department of Oral Pathology & Microbiology and is in the preliminary phase so further results are awaited.
Keywords: Caries, caries test, Oratest
|How to cite this article:|
Saxena S, Pundir S, Aena J. Oratest: A new concept to test caries activity. J Indian Soc Pedod Prev Dent 2013;31:25-8
| Introduction|| |
The oral cavity is inhabited by many different bacterial species that are involved in various diseases. Caries, gingivitis and periodontitis are of particular interest to the dentist. Caries is caused by a smaller group of known species such as mutans Streptococci, Lactobacilli and Actinomyces. 
Information about the total amount of bacteria and the composition of the oral flora may aid in the assessment of an individual's risk of contacting one of the above-mentioned diseases , and the prediction of a clinical course. In addition, a high oral bacterial load was found to confer risk for coronary heart disease and preterm low birth weight.  The complex structure and physiology of the oral ecosystem make a reliable microbiological diagnosis and its interpretation very difficult. There are three critical issues: (i) the sensitivity of detection, (ii) the reproducibility of sample taking and (iii) the relation of the findings with respect to the pathogenic and commensal flora. 
Rosenberg et al. in 1989 developed Oratest, a simple, economical, noninvasive and less time-consuming test for estimating the oral microbial level. The test is simple and consists of rinsing the mouth with 10 ml of sterile milk, 3 ml of which is mixed with 0.12 ml of 0.1% methylene blue dye and observed for color change. The present study sample consists of 25 children with dental caries and 25 controls, free of caries, gingivitis and other oral ailments. This study is being conducted in the Department of Oral Pathology and Microbiology.
Principle of oratest
Oratest is based on the rate of oxygen depletion by microorganisms in expectorated milk samples. In normal conditions, the bacterial enzyme, aerobic dehydrogenase, transfers electrons or protons to oxygen. Once oxygen gets utilized by the aerobic organisms, methylene blue acts as an electron acceptor and gets reduced to leucomethylene blue.
Thus, the reduction of methylene blue reflects the metabolic activity of the aerobic organisms.
Oratest is based on whole mouth rinsing with sterile milk, which serves to dislodge the microorganisms and also provides a substrate for their further metabolism. White color of the milk enables the observer to detect the formation of leucomethylene blue. 
| Materials and Methods|| |
The present study was conducted on 50 children of Meerut city, who were randomly selected from those who reported to the Department of Pedodontics, Subharti Dental College, Meerut.
The armamentariums used in the study were:
The sample was divided into two groups. Group I (test group) consisted of 25 children with dental caries and Group II (control group) consisted of 25 children free of caries, gingivitis and other oral ailments, with plaque scores of zero as per the Quigley-Hein Index (Plaque Index). 
- Sterile beakers
- Sterilized milk (double-toned cow milk, 3% fat, pH 6.5)
- Test tubes
- 0.1% aqueous solution of methylene blue
- 10 ml disposable syringes
- Pipette, mirror, stopwatch and test tube stand.
Criteria for selection of the test group
The criteria for selection of the test group were:
The subjects were examined and the dft index was recorded. Consent was obtained from the parents. All subjects were taken for the study after a lapse of 90 min since the last consumption of food or drink.
- dental caries involving one or more teeth,
- gingival index score of zero
- absence of abscess, draining sinus or cellulitis and
- absence of history of antibiotic for the past 1 month.
The children included in the study were given 10 ml of ultra-high-temperature sterilized cow's milk and each child was asked to rinse his/her mouth vigorously for 30 s. The expectorate was collected in the same beaker and 3 ml of this was transferred to the screw cap tube with the help of a disposable syringe. To this, 0.12 ml of 0.1% methylene blue was added, thoroughly mixed and then placed on a stand in a well-illuminated area. The tubes were observed every 10 min for any color change at the bottom that would easily be discernible in the mirror at room temperature. The time required for a color change from blue to white within a 6-mm-diameter circle on the bottom of the test tube was recorded.
| Results and Discussion|| |
The present study was performed on 50 children, 25 with dental caries and 25 controls with no oral ailments. The mean time taken for the change of color from blue to white was 55.6 ± 2.31 min in the (Group I) caries group whereas it was 278.5 ± 1.50 min for the controls (Group II). [Figure 1] and [Figure 2] The difference between the two groups was highly statistically significant [Graph 1[Additional file 1]] and [Table 1].
The average time for changing the color in Group I and Group II with SD and SEM is shown in the following table [Table 2].
A significant difference was observed in time between the two groups for changing their color. It was quite high in Group II.
Group 1 was subdivided into three subgroups according to the number of decayed teeth for convenience in the statistical analysis. Subgroup 1 had one to two carious lesions; subgroup II had three to five carious lesions whereas in subgroup III there were seven to nine carious lesions. Shortest time for color change was observed in subgroup III with maximum decayed teeth (52.2 min) and longest time was taken by subgroup I with one to two lesions (55.6 min).
The group with less than three carious lesions that took the longest time however took less time than the controls. There was also a marked difference in the three subgroups [Graph 2[Additional file 2]] and [Table 3].
This further proved the hypothesis that higher the infection, lesser was the time taken for the change in the color of the expectorate, reflecting higher oral microbial levels. This is in accordance with the findings of Rosenberg et al. 
It is obvious that around 45-50 min is the time taken for the initiation of color change, which was short in these patients, and thus the applicability of this test in these patients with rampant caries is suggested for monitoring the preventive measures.
In routine clinical practice, we face several situations where oral hygiene maintenance has to be monitored. Such situations include cases with dental caries, gingival and periodontal disease and appliance therapy. This test could prove useful in all the situations mentioned above.
The limitation of this test is the lack of specificity as positive observations can be obtained in gingivitis and other oral ailments.
In the present study, when all 50 subjects were grouped together, significant correlation was found between time required for color change and plaque index [Table 4]. Tal Haim and Rosenberg Mel  observed similar results when they compared Oratest scores with commonly used techniques for clinical evaluation of plaque levels and gingival inflammation. They also reported that higher the Oratest scores, lower the value of the plaque index (γ = 0.58, P = 0.001).
As the Oratest gives positive observations in cases of gingival diseases, periodontal diseases, halitosis, etc., its limitation is the lack of specificity as it does not identify the source of the microorganisms. The test can be easily learnt by the auxillary personnel and hence can be used as a diagnostic tool in school health programs. The positive results can easily be visualized by the practitioner, child and the parent and thus can be used to motivate. As it does not require any special instruments, it can be used to monitor the treatment progress. It can provide a baseline with which subsequent changes in clinical status and oral hygiene (i.e., following oral prophylaxis) can be monitored in a chair side or even in a home environment.
The present study thus further proved the hypothesis that higher the level of infection, lesser was the time taken for the change in color of the expectorate, reflecting higher oral microbial levels. Thus, the test can be used as one of the tools to estimate the activity of demineralization by the bacteria conducive to the suitable environment [Figure 3] and [Figure 4].
| Conclusions|| |
A caries activity test facilitates the clinical management of patients as they determine the need and extent of personalized preventive measures. It serves as an index for the success of therapeutic measures and also helps to motivate and monitor the effectiveness of educational programs relating to dietary and oral hygiene procedures. It is of particular importance in identifying high-risk groups and individuals.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4]