saliva test steps

8/12/2019 Saliva Test Steps

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S T E P W I S E

BY COLLEENCOULTER , (GC ASIA),AND LAURENCE JWALSH (UNIVERSITYOF QUEENSLAND)

Saliva is natures miracle in the mouth:saliva plays a vital role in dentalhealth as patients strive to maintain a

healthy dentition throughout their lives.

Saliva is the primary growth environmentfor ora of the oral cavity. As the physico-chemical properties of the saliva arechanged, this affects what microorganismswill grow in the mouth. In terms of mineralloss, if the environment of the mouth isacidic, then mineral loss is likely to occur;however, if the environment has an alkalinepH, then the gain of mineral is equallypossible, and in this context it is important torecognise that saliva is the major reservoirfrom which this mineral comes.

What happens when saliva stops protectingthe teeth is exactly the opposite. In the mouthwhich has a consistently low salivary pH atrest, it is not unusual to see recurrent caries,

accelerated tooth wear, dental erosion, andCandida albicans infection. Salivary testingprovides baseline information that helps theclinician determine the ability of the saliva toprotect the teeth from mineral loss. Follow-tests can then be used for monitoring.

In those patients who display acceleratedtooth wear, there is strong evidence fora critical role of saliva, particularly of theresting salivary pH. There are severalreasons for a link between salivarydysfunction and tooth wear:

reduced clearance of dietary acids, reduced pH of the saliva, thus favouring

the net loss of mineral from the teeth, reduced buffer capacity, preventing both

dietary and also endogenous acids frombeing neutralised,

reduced remineralisation of surfaces, and softening of tooth structure leading to

accelerated wear from normal wear andtear under occlusal and incisive forces,and labial wear from toothbrushing.

A saliva test is an excellent way of being ableto identify that these patients suffer fromthis particular problem, and it provides the

framework around which their managementis based. Repeat saliva testing can showwhen the lifestyle factors which drive theproblem have been corrected. Once thispoint has been reached, the dentist canthen go on to restore the teeth with some

saliva testing G O O D P R A C T I C E , G O O D S E N S E !

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con dence that the physical properties ofthe tooth structure are optimal.

STEPS IN SALIVA TESTING

This section presents a step-by-step walkthrough the saliva testing process. A salivatesting procedure normally consists of aseries of steps, which are described in moredetail in the following paragraphs:

1. the rate of production of resting salivaas a surrogate measure of hydration,

2. the viscosity of resting saliva as asurrogate for measuring its relative waterand mucin content,

3. the pH of resting saliva,4. the rate of production of stimulated

saliva,5. the pH of the stimulated saliva, and6. the buffer capacity of the stimulated

saliva.

The rst part of the procedure is to havethe patient sitting up and relaxed, and togently grasp hold of the lower lip and toblot it gently with a gauze square. The timetaken to form droplets of saliva on the minorglands of the lower lip can then be timed.Individual droplets will appear, leaving aglistening surface. The maximum timerequired for this period of observation is 60seconds. Minor salivary gland ducts whichare not producing any saliva at the end ofthis 60-second period are easy to observe.

The patient should then expectorate allresting saliva from their mouth into a smalldisposable cup. The second stage is toassess the viscosity of this saliva which canbe determined by visual examination, that is ,is it watery, bubbly, or frothy and sticky? Thisis sometimes more easily seen by placingthe cup against a dark background.

The third step is testing the pH of the

sample of resting saliva in the cup. This isdone by dipping pH test paper directly intothe sample of oral uid to wet it, and thenremoving it immediately. It is important notto let the paper dry before scoring it as thiscan affect the visual interpretation of thecolour. The individual pH value should berecorded in the patient notes. The collectioncup is then rinsed with water and shakendry, so that it can be re-used in the followingstep.

In the commonly used Saliva-Check BufferTest Kit (GC Corporation), the pH paperhas been designed speci cally to functionlike a series of traf c lights, going fromred through to yellow through to green. Thecolour can be matched directly to the scale

provided, and a red, yellow or green overallresult obtained.

The fourth step is to test the quantity ofthe stimulated saliva in order to screen forthe possibility of salivary gland disease,particularly gland damage from lymphocyticsialoadenitis which can occur with a rangeof different medical conditions. To stimulate

the production of saliva, an inert piece ofparaf n wax is typically used. The paraf nis removed from its packaging and thepatient then chews. All saliva produced in atimed period (eg. two or ve minutes) is thendrained into a cup. It is best that the patientbe left to produce the sample of stimulatedsaliva in quiet and in privacy.

The volume measured is the liquidcomponent, not any supervening frothymaterial, and this must be read at the base

of the meniscus. From this value, one canthen calculate the actual ow rate in ml/minute, which should be recorded into thepatient notes and classi ed using the traf clight system into very low, low or normal. Anormal individual should be able to produce1 ml of saliva per minute when chewing.

The fth step is to test the pH of thestimulated saliva using pH paper. Because ofthe higher concentration of bicarbonate ionsin parotid saliva, this should be markedlyhigher than the pH value at rest. The strikingcolour difference of the pH paper betweenthe resting and stimulated saliva will oftenattract the patients interest, and provides avaluable starting point for discussions as tothe protective roles of saliva.

The nal stage of the test is the buffercapacity, which is assessed by challengingthe stimulated saliva in an aqueousenvironment with differing amounts of lacticacid. A small pipette is used to withdrawa small quantity of saliva, which is then

placed on test pads to give a colour result.Suf cient saliva must be placed in order towet the pad fully. Any excess can be blottedaway.

In the GC kit, if the applied saliva has a lowbuffer capacity, the test pads will remainbright red. If the saliva has a normal buffercapacity, each of the three pads will turngreen. Intermediate results with a bluecolour and partial transitions, are alsopossible. Each pad that scores green is

given four points, a partial green/blue resultthree points, blue two points, blue/redpartial transitions one point, and red padzero points. In this way, a 12-point scale iscreated from which one can identify laterchanges in buffer capacity over time as part


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of monitoring the progress of the patient.The allotted points are tallied. If the patientscores between 10 and 12, a combinedtotal, this indicates that their buffer capacityis within the normal range. The remainingsample of stimulated saliva can also beused for other tests such as a solid phaseimmuno-assay for Streptococcus mutanslevels.

CLINICAL APPLICATIONS OF SALIVATESTING

One can use the Saliva Check Buffer TestKit in a range of clinical situations. Inpatients who present with cervical dentinalhypersensitivity, one may see severalareas where there is cervical tooth lossfrom dental erosion. In a patient who hasaccelerated tooth wear, the resting pH maybe rather low, for instance near 5.4. If thestimulated pH was also low, for example 5.8,and the buffer capacity below normal, thisindicates a more complex problem whichaffects the gland tissues such as organicsalivary gland disease.

Where there is dramatic loss of toothstructure, this could occur from wearof softened tooth structure. The restingsalivary pH may be low and near the critical

threshold. If the stimulated pH was normaland the buffer capacity also normal, onewould concentrate on occupation, recreationand medication in the rst instance. Closerexamination of the maxillary incisors wouldprovide a clue as to the presence of re ux

disease.

In a patient with incipient root surfacecaries, the resting ow rate may be low, andthe resting pH may also be low (eg. at 5.6),while the stimulated pH could be nearer thenormal range (at 6.8). In such a patient, lowbuffer capacity would suggest major salivarygland disease such as Sjogrens Syndrome,which is not uncommon in elderly femalepatients.

Similarly, patients with cervical lesionswhich encircle the teeth, a low ow rate,high viscosity and low resting pH (such as5.8) would not be unexpected. If there wasalso a low buffer test result, this would implydamage to the functional capacity of thesalivary glands.

Saliva testing helps to point the clinician inparticular directions and away from others,and it provides a means to assess changesover time as various factors in the patientslifestyle are altered. Understanding thesalivary environment is critical to achievinglong-term oral health for the patient. Onecan restore teeth, but those restorations aredoomed to fail rapidly unless the salivaryenvironment is corrected.

FOOTNOTE:

The text of this article has been adapted withpermission from the manual Saliva Testing: GoodPractice, Good Sense by LJ Walsh, published by GCAsia 2002.

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Fig 1. An overview of the saliva testing process. a) Assessing the resting ow rate using the droplet time. b) Collecting resting saliva. c) Testing the pHof resting saliva. d) Components used for testing pH and buffer capacity, comprising pH test paper, a collection vessel for sa liva and buffer test strips(packed in foil). e) Measuring the pH of the resting saliva. f) Collecting stimulated saliva into a graduated container. g) and h) Applying stimulatedsaliva to pH test paper using a pipette. i) and j) Testing buffer capacity using test pads impregnated with acid.

saliva test steps

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