Caries Risk Assessment

Introduction

The American Academy of Pediatric Dentistry (AAPD) recognizes that caries-risk assessment and management protocols can assist clinicians with decisions regarding treatment based upon caries risk and patient compliance and are essential elements of contemporary clinical care for infants, children, and adolescents.

Caries Susceptibility is an inherent property of the host and tooth to be affected by carious process.
            It refers to the number of new lesions that may develop in an individual over a period of time while caries activity suggests the number of lesions that an individual has at the time of recording (new and old). Caries susceptibility varies in different individuals, in different teeth and also on different surface of each tooth.

Primary teeth: Second molar, first molar, canine, lateral incisor, central incisor

Permanent Teeth: First molar, second molar, upper second bicuspid, upper first bicuspid and lower second bicuspid, upper central and lateral, upper central and lateral, upper cuspids and lower first bicuspids, lower central and lateral incisors and lower cuspids.

Dental caries is a biosocial disease that can be prevented if certain risk factors could be identified in susceptible individuals or community.

Caries Activity Test

Test based on the estimation of microorganism numbers have been developed to relate to caries activity. These tests aid the clinician to educate regarding their caries activity and motivate the patients in good oral hygiene practices.

Caries activity testing is essential to establish initial baseline of cariogenic pathogens as a basis for future evaluation and preventive dentistry. It is also essential to ensure low level of caries activity before starting extensive restorative procedures and to monitor patient behavior towards reducing the number of S. mutans and lactobacilli to curtail sucrose intake.

Ideal requisites of caries activity tests

1.     Caries activity test should have maximum correlation between predicted and actual caries development.

2.     It should have reliability and validity.

3.     It should be simple with regard to technical procedures and skills required.

4.     Results should be obtained rapidly, within hours or few days.

5.     There should be measurement of mechanisms involved in the carious process.

Classifications

Microbial Tests

1.     Lactobacillus count test

2.     Snyder test

3.     Alban’s test

4.     Dentocult lactobacilli test

5.     Mutans group of streptococci screening tests
        Plaque/tooth pick method
        Saliva/tongue blade method
        S. mutans adherence method
        S. mutans replicate technique
        S. mutans dipslide method

6.     Swap test

7.     Oricult test

Tests for evaluating salivary defense

1.     Salivary reductase test

2.     Dentobluff test

3.     Salivary viscosity

4.     Salivary flow rate test

5.     Fosdick calcium dissolution test

6.     Dewar test

Tests for evaluating tooth defense

1.     Critical visual examination

2.     Fluoride levels as a method to tooth resistance

3.     Intraoral cariogenecity test

4.     Past caries experience

5.     Vangaurd electronic caries detector

Lactobacilli Colony Count Test

Count of lactobacilli is one of the oldest and most widely used tests of caries activity.

High number of lactobacilli found in subjects with abundant carious lesions.

Their levels in saliva reflect the number of existing lesions and aciduric conditions in the mouth.

Procedure
5-10 ml stimulated saliva by chewing paraffin collected in sterile bottle

1:100 dilution made, mixed and 0.4 ml of each dilution spread on surface of agar plate with bent glass rod, and are incubated at 37°C for 3-4 days.

A count of number of colonies is then made with Quebec counter.

Result

No. of organism	Symbolic designation	Degree of caries
0-1,000	+	None
Less than 10,000	+	Slight
Less than 1,00,000	++	Moderate
More than 1,000,000	++++	Marked

Snyder Test

Simple calorimetric test devised by Snyder in 1951 based upon the rate of acid production when a sample of stimulated saliva is inoculated into a glucose and agar containing medium pH 4.7-5.0 containing color indicator bromocresol green.

This test estimates the number of both aciduric and acidogenic organisms in saliva because it relies on production of additional acid under already acidic culture condition.

To evaluate visually the rapidity and extent of acid production, bromocresol green indicates pH change.
A standardized color chart is used as an ad in determining color change.
At the end of 24, 48 and 72 hour color medium is recorded as 1-4 on the basis of whether the color remains the same or changes by comparison with an uninoculated tube against a white background.

Swab Test

Developed by Grainger et al in 1965 which is valuable for evaluating caries activity in very young children.
It measures the aciduric-acidogenic component of the oral flora after a suitable incubation period by employing a color indicator in the test medium or by directly reading the pH on a pH meter. Oral flora is sampled by swabbing the buccal surface of teeth with cotton applicator.

The change in pH following a 48 hour incubation is read on a pH meter or color change is read on color comparator.

Interpretation:

pH 4.1 and <4.1	Marked Caries activity
pH 4.2 - 4.6	Active
pH 4.5 – 4.6	Slightly active
pH >4.6	Caries inactive

Advantage:
Tests are of value in predicting caries increments in children.
No collection of saliva is required.

Salivary Defense Factors

Salivary Flow Rate

Unstimulated saliva collection

Patient sits up-right with head bent forward and let saliva drip into graduated tube without chewing.
0.3-0.4 ml/min average collection
if less than 0.1 ml/min, it is considered high caries risk.

Stimulated saliva collection

Patient is in upright position with head bent forward. Flow rate is determined by collecting paraffin stimulated saliva in a calibrated cylinder/test tube over a 5 min period.
Approx. 10.1 ml/5 min in male, 8.6 ml/min in female
values less than 0.7 ml/min considered high caries risk.

Viscosity of saliva

As salivary flow decreases, viscosity increases.

This inverse relation is important since saliva that is more viscid is less effective in clearing the mouth.

Viscosity is determined by comparing it with that of water.

Special Ostwald pipette with calibrated bore is used.

Relative viscosity = Time required for saliva/Time required for water, which is about 1.5.

Salivary Buffer Capacity Test

Dentobluff Strip Test

One drop of stimulated saliva is placed
on a test strip containing an acid and a
 pH indicator.

After 5 minutes, when the reaction between saliva and acid has taken place, the color of the test pad is compared to color chart of the pH indicator.

This system identifies saliva with low, intermediate and high buffer capacity.

Patients with higher buffer capacity are quite resistance to caries while those with low are susceptible to caries.

Salivary reductase test

This test measures the rate at which an indicator molecule, diazoresorcinol, changes from blue to red to colorless or leukoform on reduction by the mixed salivary flora.

Saliva is collected using special flavored paraffin and expectorated into collection tube. 5 ml of saliva mixed with the fixed amount of diazoresorcinol, the reagent upon which the reductase enzyme is to react. Color changes after 30 second and 15 minutes is taken.

Result

Score	Time	Color	Caries activity	Score
1	15 min	Blue	Non conducive	1
2	15 min	Orchid	Slightly conducive	2
3	15 min	Red	Moderately Conducive	3

Conclusion

Timely checkups and regular dental visits can help prevent dental caries in a susceptible person as well.

Caries risk assessment helps to find caries activity and helps the clinician to motivate the patient with good oral hygiene practices.

Reference

•       Textbook of PEDODONTICS, 2^nd Edition Shova Tandon

•       AAPD Guidelines (www.aapd.org)