CARIES ACTIVITY TESTS : CARIES ACTIVITY TESTS CONTENTS : 2 CONTENTS Introduction
Purpose of caries activity tests
Ideal requisites of caries activity tests
Some important terms
Caries activity tests INTRODUCTION : 3 INTRODUCTION Dental caries (latin word carius=rottenness)
Is a pathological process involving localized demineralization of the inorganic mineral portions of the tooth followed by proteolysis(breakdown of proteins into simpler compounds), resulting in a carious lesion or cavity.
Dental caries can be defined as a carbohydrate modified transmissible local infection with saliva as a critical regulator. INTRODUCTION : 4 INTRODUCTION Caries activity tests measure the degrees to which the local environment challenge (eg: dietary effect on microbial growth and metabolism) favors the probability of carious lesions. PURPOSE : 5 PURPOSE For the clinician-
To determine the need for caries control measures.
As an indicator of patient cooperation.
To act as an aid in timing of recall appointments. Slide 6: 6 As a guide to insertion of expensive restorations.
To aid in determination of prognosis.
As a precautionary signal to orthodontist in placing bands. Slide 7: 7 For the research worker-
As an aid in selection of patients for caries study.
To help in screening of potential therapeutic agents.
To serve as an indicator of periods of exacerbation and remission. IDEAL REQUISITES : 8 IDEAL REQUISITES According to Snyder:-
Have a sound theoretical basis.
Show maximum correlation with clinical status.
Should have validity, reliability and feasibility.
Be accurate with clinical status.
Take little time. Some important terms : 9 Caries activity-
refers to the increment of active lesions(new and recurrent) over a period of time. It is a measure of speed of progression of disease.
refers to the inherent tendency of the host and target tissue, the tooth to be afflicted by the caries process. It is the susceptibility of the tooth to a caries producing environment. Some important terms Slide 10: 10 Caries risk assessment-
procedure to predict the future caries development before the clinical onset of disease.
Caries activity test estimates the actual state of disease activity (progression/ regression). Characteristics Of Caries Predictive Test : Characteristics Of Caries Predictive Test VALIDITY:- child, if placed in a high caries activity category and followed for 2 yrs, should demonstrate high caries increment. Conversely, a child in a low caries activity category should have minimal or no caries increment 11 Slide 12: RELIABILTY:- It implies that when the test is performed on different occasion, it will give reproducible results.
FEADIBILITY:- are those that lend themselves to use in public health programs or for large clinical trials because they are inexpensive , noninvasive and easy to use by semiskilled personnel 12 Factors used in evaluation of caries risk : 13 Factors used in evaluation of caries risk Caries activity tests for the dental office : 14 Caries activity tests for the dental office Dental caries is multifactorial and of complex etiology.
No test is present which can fully explain or predict the disease.
With caries activity tests information can be obtained on selected factors of importance for the process.
The tests should be simple and inexpensive and rapid and accurately reflect the 3 overlapping circles presented by KEYS. Slide 15: 15 In the light of these requirements and circles, caries activity tests can be grouped under:
Bacterial challenge- determination of mutans streptococci as an indicator of relative risk.
Diet- determination of lactobacilli as an indicator of sugar content in the diet. Slide 16: 16 3. Remineralization potential- salivary flow rate and buffer capacity as an indicator of potential biologic repair.
4. Host susceptibility- caries experience as an indicator of past activity. When should the tests be used : 17 When should the tests be used Clarify the reasons behind an on going disease and formulate and motivate the preventive strategy to the patient.
Determine the effect of a causal treatment at follow up visits.
Predict caries development (ie; make a prognosis) at check up visits. Lactobacillus colony count test : 18 Lactobacillus colony count test This test was first introduced by HADLEY in 1933.
Action-estimates the no. of acidogenic and aciduric bacteria in the patient’s saliva by counting the no. of colonies appearing.
Equipment- saliva collecting bottles, paraffin, 2 9ml tubes of saline, 2 agar plates, 2 bent rods, incubator, quebec counter and pipettes. Slide 19: 19 Procedure-
Saliva is collected by having the subject chew paraffin before breakfast and then collecting the saliva in a bottle.
Specimen is shaken to mix it. Slide 20: 20 A 1:10 dilution is prepared by pipetting 1ml of saliva sample into a 9ml tube of sterile saline solution.
This is shaken and a 1:100dilution is made by pipetting 1ml of 1:10 dilution into another 9ml tube of sterile salt solution. Slide 21: 21 0.4ml of each dilution is spread on the surface of an agar plate.
The plates are labelled and incubated at 37 deg C for 3-4 days.
A count of the no. of colonies is then made by using quebec counter. Results : 22 Results Slide 23: 23 Advantages-
Useful for monitoring the effectiveness of restorative dentistry and care completion.
2. Simple to carry out.
3. Useful as a screening test for caries activity in large groups. Slide 24: 24 Disadvantages-
The results are not available for several days.
Cost is relatively high.
Inaccurate for predicting the onset of disease.
Does not completely exclude the growth of other relatively aciduric organisms.
Counting is a tedious procedure. Snyder test : 25 Snyder test Action-measures the rapidity of acid formation when a sample of stimulated saliva is inoculated into glucose agar with bromocresol green as color indicator.
The test is also a measure of acidogenic and aciduric bacteria. Slide 26: 26 Procedure-
Saliva is collected before breakfast by having the subject chew paraffin.
A tube of snyder glucose agar is melted and then cooled to 50 deg C. Slide 27: 27 The saliva specimen is shaken vigourously for 3 mins.and 0.2 ml of saliva is pipetted into the tube and incubated at 37 deg C.
The color change of the indicator is observed after 24, 48, 72 hrs of incubation by comparison with an uninoculated tube against a white background. Color changes in snyder test : 28 Color changes in snyder test incubation at 37 deg C
0.2cc of saliva Slide 29: 29 Tube 1: Uninoculated Synder tube
Tube 2: No color change indicates little or no susceptibility to forming dental caries
Tube 3: Sight color change indicates mild susceptibility to forming dental caries
Tube 4: Significant color change indicates moderate susceptibility to forming dental cariesTube 5: Complete color change indicates high susceptibility to forming dental caries. Slide 30: 30 Advantages-
Test is simple and requires simple equipment.
Test takes only 24-48 hrs
Cost is moderate. Slide 31: 31 Disadvantage of snyder and lactobacillus count test-
Neither of the test can predict the extent of expectancy of caries with any reliability for one individual. Slide 32: 32 Several modifications of snyder test have been proposed to further simplify the method for use in dental office-
A smaller volume(0.2ml) of culture media is inoculated with saliva using caliberated wire loop. This avoids use of pipettes and saves medium and space. Slide 33: 33 2. Alban’s method uses less agar in the medium so that tubes do not require melting.There is no attempt to quantitate the salivary inoculum, which is drooled directly into the tube.
3. The buccal surfaces are swabbed and the cotton applicator incubated in semifluid snyder medium. This has advantage of culturing directly from plaque. Buffer capacity test : 34 Buffer capacity test Action- test measures the no. of millilitres of acid required to lower the ph of saliva through an arbitrary pH interval, such as from pH 7.0 to 6.0, or the amount of acid or base necessary to bring color indicators to their end point.
Equipment- pH meter and titration equipment, 0.05N lactic acid, 0.05N base, paraffin and sterile glass jars containing a small amount of oil. Slide 35: 35 Procedure-
10 millilitres of stimulated saliva are collected under oil atleast 1 hour before eating.
5ml of this are measured into a beaker. After correcting the pH meter to room temp.The pH of the saliva is adjusted to 7.0 by addition of lactic acid or base. Slide 36: 36 Lactic acid is then added to the sample until a pH of 6.0 is reached. The no. of the milliliters of lactic acid needed to reduce pH fro 7.0 to 6.0 is a measure of buffer capacity. Slide 37: 37 There is an inverse relationship between buffering capacity of saliva and caries activity.
The saliva of the individuals whose mouths contain considerable amount of carious lesions frequently has a lower acid buffering capacity than the saliva of those who are relatively caries free.
This test however does not correlate with caries activity. Fosdick calcium dissolution test : 38 Fosdick calcium dissolution test Action- measures the milligrams of powdered enamel dissolved in 4hrs by acid formed when the patient’s saliva is mixed with glucose and powdered enamel.
Equipment- powdered human enamel, saliva collection bottles, sterile test tubes, test tube agitation equipment, and equipment for determining the calcium content of saliva. Slide 39: 39 Procedure-
Twenty five milliliters of gum stimulated saliva collected.
Part of this is analyzed for calcium content.
The rest is placed in an 8 inch sterile test tube with about 0.1g of powdered human enamel. Slide 40: 40 The tube is sealed and shaken for 4hrs at body temp after which it is again analyzed for calcium content.
The chewing of gum to stimulate the saliva produces sugar, if paraffin is used a concentration of about 5% glucose is added.
The ampount enamel dissolution increases as the caries activity increases Slide 41: 41 Advantages-
Requires only 4 hrs.
Test is not simple
Equipment is complex
Cost is high Dewar test : 42 Dewar test This test is similar to fosdick calcium dissolution test except that the final pH after 4 hrs is measured instead of the amount of calcium dissolved.
This test has not been adequately tested for clinical correlation. Mutans Group Of Streptococci Screening Tests : Mutans Group Of Streptococci Screening Tests 43 Plaque/toothpick method : 44 Plaque/toothpick method Action- involves simple screening of a diluted plaque sample streaked on selective culture medium.
2.sterile ringer’s solution(5ml)
4.mitis salivaris agar plates containing sulphadiametine(1g/l)
5.incubator Slide 45: 45 Plaque samples are collected from gingival third of buccal tooth surfaces(one from each quadrant) and placed in ringer’s solution.
The sample is shaken until homogenized. Slide 46: 46 Plaque suspension is streaked across a mitis salivarius agar plate.
After aerobic incubation at 37deg C for 72 hrs, cultures are examined under a low power microscope and the total colonies in ten fields are recorded. Results of s mutans screening test : 47 Results of s mutans screening test From woods
*6 to 15 yrs
#11 to 13 months Saliva/tongue blade method : 48 Saliva/tongue blade method Action-estimates the no. of s mutans in mixed paraffin stimulated saliva when cultured on mitis salivarius bacitracin(MSB) agar.
Equipment- 1.paraffin wax
2.sterile tongue blades
3.disposable contact petridish containing MSB agar
4.incubator Slide 49: 49 Procedure-
Subjects chew paraffin wax for 1 min.
Then sterile tongue blades are given which the subjects rotate in their mouths 10 times, so that both the sides of the tongue blade are thoroughly inoculated by the subject’s flora. Slide 50: 50 Slide 51: 51 Tongue blade is withdrawn through closed lips. Both the sides of the tongue blade are then pressed onto an MSB agar plate which is then incubated at 37 deg c for 48 hrs.
Counts of more than 100CFU by this method are proportional to greater than 106 CFU of S mutans per ml of saliva by conventional methods. Slide 52: 52 For field studies the plates are placed into plastic bags containing expired air, which are then sealed and incubated.
An updated or simpler version of this method, strip mutans (orion diagnostica), uses a liquid medium with a long shelf life, to which the bacitracin is added just before incubation. Slide 53: 53 A plastic spatula instead of wooden blade is used. Colonies of mutans streptococci grow directly on the spatula, which is then removed from the liquid medium, drained and placed under microscope for counting. Slide 54: 54 Slide 55: 55 Advantages-
Simple and practical method for field studies
Requires no transport media/dilution stops S mutans adherence test : 56 S mutans adherence test Action- categorizes salivary samples based on the ability of s mutans to adhere to glass surfaces when grown in sucrose containing broth.
unstimulated saliva (0.1ml) is inoculated in MSB broth. The inoculated tubes are set at 60deg angle and incubated aerobically at 37 deg c for 24 hrs. After growth has been observed, supernatant medium is removed and cells adhering to the glass surface are examined macroscopically. Scoring : 57 Scoring S mutans dip-slide method : 58 S mutans dip-slide method Action- these tests comprise of Dentocult SM, Cariescreen SM.
These tests classify salivary samples according to estimates of s mutans colonies growing on modified mitis salivarius agar.
Equipment- paraffin wax, plastic slides coated with MS agar, CO2 tablets, buffered diluent. Slide 59: 59 Procedure A- (Dentocult SM)
Subject chews paraffin wax and stimulated saliva is collected for 5 mins.
Saliva is poured over agar coated slide, totally wetting the surface, and excess is allowed to drain off. Slide 60: 60 Slides are dried for 10-15mins, bacitracin disks are placed in middle of the inoculated agar.
A co2 tablet is inserted in the tube containing the slide, which is then incubated for 48hrs. Slide 61: 61 A zone of inhibition 10-20 mm in diameter is formed around each bacitracin disk.
S mutans appears as blue colonies growing within the zone of inhibition.
The colony density is compared with a model chart. Dentocult SM strip mutans test : 62 Dentocult SM strip mutans test Sample collection using Screening Strips Sample application using Site Strips Slide 63: 63 Incubation(48 hours) Interpretation(Site Strips) Slide 64: 64 Procedure B-( Cariescreen SM)
Bacitracin tablet is placed in buffered diluent and allowed to dissolve completely.
Subject chews paraffin wax for 15-20 sec swallowing the saliva. Slide 65: 65 While continuing to chew the wax the subject expectorates approx 1-2 ml of stimulated saliva directly into diluent vial, which is then capped and gently mixed by repeated inversion.
The dip slide coated on both sides with MSB agar( without bacitracin), is then immersed for few sec in the buffered diluent containing bacitracin and patient’s saliva. Slide 66: 66 A co2 tablet is placed in the empty dip slide vial, and 2 drops of water are added.
The dip slide is replaced in its vial and cap is securely tightened.
The vial is placed upright for 48hrs at 37 deg C in an incubator and then allowed to stand at room temp overnight. Slide 67: 67 The colony density on agar is compared with a reference colony density chart.
This test correlates strongly with actual laboratory methods of quantifying s mutans by standard culturing.
The s mutans colonies can be recognized when viewed through a magnifying lens by their opaque, highly convex appearance and irregular shape. S mutans replicate technique : 68 S mutans replicate technique Action- localizes s mutans colonies on tooth surfaces using a solid impression matrix composed primarily of sucrose and commercial gum base.
imprint of tooth surface to be sampled is obtained by pressing the matrix against it. Slide 69: 69 Matrix is washed for several sec in water to remove non adherent cells and saliva.
Matrices are placed in liquid broth and incubated at 37 deg C overnight and examined directly for overgrowth of s mutans colonies at specific sites. Prediction of future caries activity based on previous caries experience : 70 Prediction of future caries activity based on previous caries experience Action- as an alternative to chemical or bacteriological tests for determining caries activity, previous caries experience can be reasonable indication of future trends. It is better to omit occlusal surfaces in such estimates.
Equipment- dental light, mirror, explorer, radiographs. Slide 71: 71 Procedure-
Koch grouped 9-10yr old children into a high caries active group and a low caries active group on the basis of restored:-
Proximal surfaces of incisors and first permanent molars. Slide 72: 72 Buccal surfaces of maxillary first permanent molars.
3. Lingual surfaces of mandibular first permanent molars. Slide 73: 73 Those who had a score of 4 or more were considered high caries active whereas those who had a 0 score were considered low caries active. Slide 74: 74 Drawbacks-
Caries will have already occurred in the population.
This method is not applicable to very young, when preventive intervention is desirable.
This method requires professional dental examination. Reference : Reference Cariology Third Edition (Ernest Newbrun, DMD, PhD)
Internet 75 Thank you : Thank you 76