Additional methods of examination of patient: thermodiagnostics, EOD, use of caries detectors

2. Extra methods of dental patient examination: temperature test, electric pulp testing (EPT), use of caries detectors. X-rays diagnostics, luminescent and transluminative diagnostics. Laboratory methods of diagnostic. Interpretation of results.

Diagnosis in dentistry may be defined as ‘the process whereby the data obtained from questioning, examining and testing are combined by the dentist to identify deviations from the normal. The diagnosis of dental pulp status should be seen as a synthesis of history, clinical examination, special tests, and radiological examination, and not as the outcome of any one specific test. Vitality testing is an important aid in the diagnosis of pulp disease and apical periodontitis. If the pulp is deemed to be severely compromised as a result of the diagnostic testing, then endodontic treatment, or indeed extraction, may be indicated.

DIAGNOSTIC METHODS FOR DENTAL CARIES

Clinical methods

Caries occurs on the occlusal, aproximal and buccal/ lingual surfaces of teeth. On smooth surfaces the lesions normally develop close to the gingival margin and are often covered in plaque. Those developing in fissures and aproximal surfaces are more difficult to detect and diagnosis usually involves indirect methods. Diagnostic tests have been developed to maximise the accuracy of caries detection on each surface. On the buccal and lingual surfaces the optimal assessment is the visual appearance of the surface. A white spot lesion can be seen when enamel has been cleaned and dried. The area is often covered in plaque. On those surfaces hidden from direct visual examination, radiographic examination is the most commonly used diagnostic technique.

 

VISUAL

The Ekstrand system utilises the knowledge that as demineralisation progresses in enamel it spreads laterally. As the process advances into dentine there is  a suggestion that the enamel is undermined. Ekstrand (1998) showed in microbiological studies that there is an equivalent demineralisation front occurring in the overlying enamel. This progression can be examined using a simple process. A clean and well dried enamel surface is assessed for surface integrity and enamel demineralisation and whitening (equivalent to increase in surface porosity). The enamel surface must be thoroughly cleaned and dried. An intact surface without demineralisation indicates a non-advancing lesion. White demineralisation and a break in the enamel surface show that dentine is involved. If the surface is completely dry it is possible to see that the spread of the enamel decalcification matches that of the spread of caries in dentine. Probably the most difficult lesion to assess is recurrent caries occurring around existing restorations. Marginal gaps and ditching are common around most amalgam and tooth-coloured restorations. The distinction between caries and localised material collapse is difficult, with many clinicians interpreting the same appearance in different ways. Marginal gaps which are sticky to probing and are wider than the width of a periodontal probe would generally mean that caries is present and there is a need for operative management. However, pure ditching (which is a breakdown of the amalgam at the tooth surface) does not require restoration. Unlike direct examination of caries, the colour of recurrent caries can aid the process. Shadowing and a blue–brown discolouration within the tooth and surrounding the restoration can indicate an active lesion.

 

RADIOGRAPHY

Figure 4.10 Bite wing radiograph showing interproximal caries in the contact areas.

 

Bitewing radiographs are relatively reliable for detecting aproximal lesions but less so for occlusal lesions. Radiolucencies developing below the contact areas appear like horizontal V-shaped notches in enamel-only lesions (Fig. 4.10). As the lesion progresses into dentine,  a mushroom formation occurs as the enamel appears to be undermined along the enamel–dentine junction (EDJ). The situation is more difficult to assess on the occlusal surfaces as the more mineralised and thicker enamel partly obscures the lesion progression. The advancing lesion is therefore relatively underdiagnosed by radiographs. A rough guide suggests that a lesion is 25% more advanced than when estimated from a radiograph. A bitewing radiograph needs to be taken correctly to have the most diagnostic yield. Film holders yield the most accurate results and ensure that the X-rays pass perpendicularly through the crown of the tooth. This reduces the amount of overlap. A clear outline should be visible of the enamel overlying the dentine and allows good distinction between the two tissues. A clear change in the radiolucency of the tooth can then be seen. Caries appears as radiolucent shadowing and occurs at susceptible sites. Aproximally, this will occur below the contact area and above the alveolar bone. Beneath the occlusal surfaces the faint outline of caries can be detected. The radiolucent zone appears as a diffuse zone beneath the enamel. The extent of the lesion spread is more difficult to visualise as the bulk of the enamel and dentine partly obscures the X-rays; this results in a less accurate assessment of occlusal caries compared to that occurring aproximally. The frequency of bitewing radiographs should be assessed for each individual. A high caries risk individual might require radiographs taken at yearly intervals whereas someone with no caries experience for a number of years would need them less frequently, e.g. every 4–5 years.

Panoramic X-ray, kid of 5 year – follicles of all permanent teeth are visible.

 

TEMPERATURE TEST

Tooth with normal (intact) pulp responds to significant temperature deviations.

Neutral zone (no reaction) for incisors is 30 ° C (50-52 ° C – reaction to heat, 17 – 22 ° C – on cooling).

Thermal testing

 These tests involve the application of cold and heat stimuli to a tooth, to determine sensitivity to thermal changes. Although both are tests of sensitivity, they are actually conducted for different diagnostic reasons. A response to cold usually indicates a vital pulp, regardless of whether that pulp is normal or abnormal. In contrast, an increased response to heat is suggestive of pulpal or periapical pathology that may require endodontic intervention.

Cold tests

 Cold thermal testing causes contraction of the dentinal fluid within the dentinal tubules, resulting in a rapid outward flow of fluid within the patent tubules. This rapid movement of dentinal fluid results in ‘hydrodynamic forces’ acting on the Aδ nerve fibres within the pulp–dentine complex, leading to a sharp sensation lasting for the duration of the thermal test. A variety of cold tests may be employed, the major difference between them is the degree of cold that is applied to the tooth. The most common pulp testing method employed by practitioners is to seek a response to a cold stimuli. Ideally, cold testing should be used in conjunction with an electric pulp tester so that the results from one test will verify the findings of the other test. If a mature, non-traumatized tooth does not respond either to EPT or cold, then the tooth may be considered non-vital. However, caution should be exercised when testing multi-rooted teeth, as they may respond positively to cold, even though only one root actually contains vital pulp tissue. The cold test may be used to differentiate between reversible and irreversible pulpitis. It should be noted, however, whether stimulus application produces a lingering effect or if the pain subsides immediately on removal of the stimulus from the tooth. If the patient feels a lingering pain, even after the cold stimulus is removed, a diagnosis of irreversible pulpitis may be reached. Conversely, if the pain subsides immediately after stimulus removal, a diagnosis of reversible pulpitis is more likely. The clinician should also take into consideration other factors such as a history of pain on lying down and the duration of pain. The diagnosis of reversible/irreversible pulpitis is only a clinical diagnosis and may not correlate with a histological diagnosis.

A simple means of applying a cold stimulus to a tooth is to wrap a sliver of ice in wet gauze and place it against the buccal surface, comparing the reaction between the test tooth and a control tooth. Pencils of ice can be made by filling a plastic straw with water and freezing it in an upright position in a refrigerator. Ethyl chloride (boiling point – 41 °C) may be sprayed onto a cotton pledget, resulting in the formation of ice crystals, prior to application to the tooth. Dichlorodifluoromethane (DDM) (boiling point – 0 °C) is a compressed refrigerant spray, which can similarly be sprayed onto a cotton pledget for cold testing. More recently, ozone-friendly non-chlorofluorocarbon sprays have been introduced in certain countries. Another effective cold stimulus is frozencarbon dioxide (CO2), also known as ‘dry ice’ or ‘carbon dioxide snow’ (boiling point – 72 °C).

For testing purposes, a solid stick of CO2 gas is prepared by delivering CO2 gas into a custom-made plastic cylinder and the stick is applied to buccal surface of the tooth. This investigation is particularly effective when trying to assess teeth that have been restored with full-coverage metal restorations reported that CO2 snow applied to a tooth for min did not jeopardize the health of the pulp, nor does it damage the surface of the enamel. On the other hand, CO2 may cause pitting of the surface of porcelain restorations when applied for as little as 5 s. When testing with a cold stimulus, one must begin with the most posterior tooth and advance towards the anterior teeth. Such a sequence will prevent any melted ice water dripping in a posterior direction which may cause stimulation of other teeth, thereby giving a false response.

Ice-cold water is another useful and in expensive test. The tooth under investigation should be isolated with rubber dam and then bathed with water from a syringe. Cold tests should be applied until the patient definitely responds or the stimulus has been applied for a maximum of 15 s. Overall, cold tests appear to be more reliable than heat tests. Furthermore, there is a general consensus that the colder the stimulus, the more effective the assessment of tooth innervation status.

Heat test

 Heat testing can be undertaken using a stick of heated gutta-percha or hot water. A gutta-percha stick, preferably base-plate gutta-percha, is heated with a naked flame or an electric heater until it becomes soft and glistens. It is then applied to the vaseline-coated surface of the test tooth. It is purported that a tooth surface temperature as high as 150 °C can be achieved with this technique: gutta-percha softens at 65 °C and may be heated in delivery devices up to 200 °C. This test may be difficult to use on posterior teeth because of limited access. A further disadvantage is that excessive heating may result in pulp damage. Prolonged heat application will result in bi-phasic stimulation of Aδ fibres initially, followed by the pulpal C fibres. Activation of C fibres may result in a lingering pain, therefore heat tests should be applied for no more than 5 s. However, inadequate heating of the gutta-percha stick could result in the stimulus being too weak to elicit a response from the pulp. The use of hot water, administered through an irrigating syringe under rubber dam isolation, has also been described as a means of thermal testing. Frictional heat may be generated by using a rubber cup intended for prophylaxis (without paste) against the buccal aspect of a tooth. The normal use of thermal tests on teeth has been showot to be harmful to healthy pulp tissue.

 

CARIES DETECTOR

 

CARIES DETECTOR is an excellent means of detecting caries and plays a major role in maintaining and preserving teeth. It provides support for the excavation of the demineralized outer tooth hard structure affected by the caries, making it possible to remove the caries as completely as possible. At the same time, it makes sure that as little healthy dentin which can be remineralized is removed as possible, secures pulp vitality, and preserves the healthy tooth structure. Numerous studies have shown that it is not possible to distinguish, either optically or mechanically using the sensor test, between irreversibly diseased dentin and healthy dentin which can be remineralized. Using CARIES DETECTOR, you can confidently proceed with the excavation because only the irreversibly diseased dentin is stained red.

 

Caries-Detecting Dyes

In 1972, a technique using a basic fuchsin red stain was suggested (and subsequently developed) to aid in the differentiation of the two layers of carious dentin. Because of potential carcinogenicity, the basic fuchsin stain was subsequently replaced by another dye, acid red solution. Since then, various protein dyes have been marketed as caries-detection agents. Intended to enhance complete removal of infected carious dentin without over-reduction of sound dentin, the dye was purported to stain only infected tissue and was advocated for a “painless” caries removal technique without local anesthetic. The technique was laborious, as it was guided by staining, involved multiple dye application-and-removal repetitions and required the use of a slow-speed bur.

Tactile and visual criteria are normally used to render a cavity caries-free, and the idea of a diagnostic aid that would differentiate infected dentin was considered desirable. Subsequent clinical trials were done in the United States and United Kingdom involving the use of the dye in cavities prepared by dental students and judged to be caries-free by their clinic instructors; the trials revealed dye-stained dentin in 57% to 59% of cavities at the enamel–dentin junction. This finding implied that the clinical judgment of the teachers was often flawed and that the prevalence of residual decay was high. The conclusion was made despite the fact that the laboratory component of the U.K. study did not correlate dye-stained material with infection but rather with lower levels of mineralization, with or without infection. Interestingly, all authors showed particular concern for the amelo-dentinal junction. It is of note that dye stain on more than 50% of the cavity pulpal floors judged by instructors to be complete was considered an inappropriate indication for further dentin removal by the researchers, as it would result in unnecessary pulpal exposures.

Accuracy of Caries-Detector Dyes

A diagnostic aid should show a very low level of false positives to avoid unnecessary treatment. Yet in one study, when the level of infection of dye-stained and unstained dentin at the amelo-dentinal junction was measured at the completion of cavity preparation, it was discovered that not all dye- stainable dentin was infected. Fifty-two per cent of the completed cavities showed stain in some part of the enamel–dentin junction, but subsequent microbiological analysis of dye-stained and non-stained sites resulted in the recovery of very light levels of infection, with no differences between sites. Such bacterial levels were considered clinically insignificant. On the other hand, it has also been demonstrated that absence of stain does not ensure elimination of bacteria.

It is now clearly established that these dyes do not stain bacteria but instead stain the organic matrix of less mineralized dentin. The lack of specificity of caries-detector dyes was confirmed in 1994 by Yip and others, who correlated the location of dye-stainable dentin with mineral density. The dyes neither stained bacteria nor delineated the bacterial front but did stain collagen associated with less mineralized organic matrix. Of even greater significance was the fact that when these authors utilized the dyes on caries-free, freshly extracted human primary and permanent teeth, they discovered that sound circumpulpal dentin and sound dentin at the amelo-dentinal junction took up the stain because of the higher proportion of organic matrix normally present in these sites. Clearly, the routine use of these dyes without an understanding of their distinct limitations will result in excessive removal of totally sound tooth structure and increased likelihood of mechanical pulp exposures.

Dye staining and bacterial penetration are independent phenomena, which significantly limits the usefulness of these dyes for diagnostic purposes. Quantification of the intensity of staining may give a measure of severely diseased tissue, and the contrast afforded by dyes may help identify carious dentin if tactile discrimination is unavailable. However, most clinical investigations have concluded that conventional tactile and optical criteria are the most satisfactory assessment of caries status during cavity preparation and that subsequent use of a caries-detector dye could result in unnecessary removal of sound tooth tissue. Dye-stainable status is not a good predictor for the presence or absence of bacteria in dentin and lacks the necessary specificity for the accurate detection of carious dentin.

Pit and Fissure Occlusal Caries

Fissure caries continues to be a significant clinical problem, despite overall reductions in the prevalence of smooth-surface caries since the advent of fluoride. The point at which operative intervention is required depends on the presence of significant dentinal infection, and this diagnosis can be difficult in the absence of cavitation. Visual occlusal cavitation has been shown to be synonymous with dentinal involvement, but it is generally accepted that diagnosis of dentinal decay beneath discoloured and slightly defective fissures, or even under apparently sound occlusal fissures, can be challenging.

Diagnostic methods include probing (which may actually cause infection or traumatic micro-cavitation), optical criteria, bitewing radiography and electronic caries detectors. Early detection of occlusal lesions is advantageous primarily because it enables the benefits of therapeutic prevention with sealants. As early as 1984, a National Institutes of Health Consensus Development Conference concluded not only that the placement of sealants is a highly effective means of preventing pit and fissure caries but that “the evidence is overwhelming that the vitality of the dental pulp is not endangered by incidental placing of sealants over small pit and fissure lesions. In fact, minor carious lesions covered by sealants seem to become inactive and the process of tooth decay is apparently arrested by the sealant. Investigators have reported negative or reduced bacterial cultures following several years of sealing. No studies have identified significant caries progression beneath an intact sealant.”

Thus, there is substantial evidence to support the contention that a small amount of diagnosed or undiagnosed dentinal caries at the base of fissures would be arrested by the application of resin sealant. Amongst other investigators, Handelman and others sealed frank carious occlusal cavities following microbiological sampling of dentin. After two years, the decrease in viable micro-organisms in the sealed teeth was 99.9%. Clinical and radiological findings indicated that the lesions were arrested. Similarly, Going and others covered dentinal carious lesions with a sealant for a five-year period. Re-entry revealed that sealant treatment alone had resulted in 89% caries reversal. More recent clinical studies have also confirmed the arrested progress of sealed carious dentin, demonstrating that concern about the possible progression of minor carious lesions beneath fissure sealants, undetectable on radiographs, is unfounded.

Use of Caries-Detector Dyes for Occlusal Caries

The value of using dyes for carious enamel detection has proven even more dubious than for dentin. Many, such as procion dyes, produce irreversible staining, which would be clinically unacceptable. The intensity of fluorescent dyes has been found to correlate with mineral loss but, as with the dentinal caries-detector dyes, they are specific only for demineralization.

Dentin demineralization beneath non-cavitated enamel can be reliably predicted by an electronic caries detector. However, studies have shown that subsequent dentin samples indicate no or only a very low level of bacterial infection. Neither visioor electronic readings reliably predicted heavily infected dentin in such cases. Bitewing radiographic analysis was found to be the most reliable diagnostic method. Bacterial counts obtained from radiologically sound fissures were low, and when lesions were radiographically visible in dentin, a significant increase in dentin infection was found. This points to the use of fissure sealing as the appropriate management of affected susceptible fissures that appear sound radiographically.

Given the overwhelming evidence for efficacy and lack of clinical problems with a philosophy of erring on the side of conservatism, the trend to rationalization of invasive treatment for the “diagnosis” of occlusal carious lesions is disturbing. There is a lack of substantive scientific literature supporting the use of dyes on defective or sound occlusal fissures to diagnose infected carious enamel or dentin. The use of surgical intervention subsequent to dye application, usually with air-abrasion techniques, as a method of confirming diagnosis is especially disturbing when based on the use of non-specific protein dyes to identify caries. The fact that such dyes staiormal dentin at the amelo-dentinal junction totally negates this concept. It is a great pity that the reputation of the air-abrasion technique for conservative operative dentistry is being sullied by non-scientific methods of caries diagnosis. Valid, accurate methods of diagnosis would be welcomed by dentists, but caries-detecting dyes fail to provide substantive usefulness. These non-specific dyes will stain food debris, enamel pellicle and any other organic matter trapped in substantial amounts in occlusal fissures and possibly will also stain demineralized enamel. False positives are a significant concern. Balanced against the largely insignificant consequences of false negatives in the diagnosis of incipient occlusal dentinal caries, which can be successfully sealed, the use of an unsubstantiated diagnostic procedure is clearly inappropriate. “Caries in industrialized countries is a disease of slow progression and it is unlikely that a missed borderline dentinal lesion will pose an early threat to the viability of the tooth. Yet the consequences of a false positive decision in clinical terms is the unnecessary filling of a sound tooth and initiation of a cycle of repetitive repair.”

Ideal caries diagnostic methods reduce the risk of unnecessary operative intervention. Currently, a combination of careful visual inspection and radiographic diagnosis would appear to best fulfill the diagnostic requirements for occlusal caries. Together, such criteria produced an 82% and 91% correct diagnosis in permanent and primary molars respectively in a sample of teeth with questionable or minimal caries without visible evidence of cavitation. This level of diagnostic accuracy is of the same order as that found in an in vitro study for a new laser fluorescence system developed for detection of occlusal caries without the use of radiographs. As stated by the authors, the potential utility of such methods of early accurate diagnosis “is to facilitate prevention-based management of dental caries, not merely as a device to aid in the location of dentinal lesions requiring fillings.” It is imperative that the field of dentistry not negate the significant advances made in disease prevention and move backward.

Conclusions

Any diagnostic procedure for the diagnosis of carious tooth structure must be specific, valid, reliable and clinically proven. Caries-detector dyes should therefore stain only in a manner that permits proper discrimination between healthy and diseased tooth structures. As none of the available caries-detection dyes is caries specific, their routine use may lead to a profound degree of over-treatment. Unnecessarily invasive treatment weakens the tooth and is more likely to threaten the health of the dental pulp. A considerable body of evidence shows that careful and thorough use of tactile and visual criteria provides an acceptable assessment of the caries status of dentin during cavity preparation.

Similarly, unnecessary initiation of operative intervention condemns the tooth to a lifetime of restorative care through the re-restoration cycle, with concomitant economic costs and a greater likelihood of premature tooth loss. A combination of visual examination and optimal bitewing radiographs provides the most reliable diagnostic technique for predicting the need for operative treatment of infected dentin under defective or pronounced occlusal fissures. Enamel fissure defects without evidence of cavitation or dentinal involvement are best treated by fissure sealants. There is a considerable body of evidence showing that the inadvertent sealing of early dentinal caries by a fissure sealant is of little consequence, as it will become arrested and not progress. There is a lack of substantive scientific evidence supporting the use of caries-detecting dyes on apparently sound occlusal fissures to diagnose underlying dentinal caries.

TRANSILLUMINATION

This is a rarely used technique to assess caries on molars and premolars but more commonly used on anterior teeth. Direct light reflected by dental mirrors on to the teeth can highlight darkened shadows present between the aproximal surfaces of upper anterior teeth. A carious lesion shows as a darkened shadowed area in dentine surrounded by a normal coloured zone. Light curing lamps can be used to examine the surfaces as white intraoral lights are not common. These lights need to be directed between the contacts of teeth and have sufficient intensity to show the caries. Generally, ambient light sources need to be reduced to improve the reliability of the diagnosis.

Tooth separators

Orthodontic separators have been reported to be useful for directly examining the aproximal areas between contacting teeth. Orthodontic elastic bands are placed between teeth and over a few days gradually separate the teeth so that direct visual inspection of the surfaces can be undertaken. Once the contacts are broken, the lesion is inspected and, if sufficient access is available, operative management commenced if necessary. This procedure is, however, rarely used in clinical practice.

 

ELECTRONIC CARIES METERS

Recent research has suggested that changes to the electrical impedance of enamel can indicate an active lesion. Small d.c. voltages have less resistance in carious enamel than that through an intact surface. The instrument needs a clean and dry surface to work efficiently and is generally used on the occlusal surfaces of molars and premolars. The advantage of using this technique is that it is the occlusal surfaces of molar and premolar teeth where radiographic assessment of caries is less accurate than the aproximal surface. The tip of the probe is less than 1 mm in diameter and can detect changes in the impedance of enamel over very small areas. This means that over small areas the instrument might be very accurate at detecting early carious lesions, but the reliability over larger areas has been questioned. If anything, this technique has the potential to overdiagnose caries by giving false-positive results and so has not resulted in widespread usage.

 

 

 

Figure DIAGNOdent instrument for the detection of carious lesions.

 

DIAGNOdent

This technique, currently commercially available as  an instrument called the DIAGNOdent (KaVo), utilizes the reflectivity of light from the tooth surface. The light reflectivity from a carious and non-carious surface is  different. The instrument is calibrated to detect this difference and informs the operator through a read out. Like the electronic caries meters, these instruments can overdiagnose caries and potentially confuse stained surfaces with carious ones. In addition, some restorative materials have shown similar fluorescent values to those of carious dentine and its application for the detection of secondary caries seems questionable. As a result, these instruments have also not seen wide usage.

 

Measurement of tooth mobility

 

Tooth mobility is assessed using two handles of two hand instruments positioned buccally and lingually. The tooth is moved bucco-lingually with the instruments and the degree of movement recorded (Table 5.2).

 

 

 

This crude system is very subjective but remains the only method in universal use. Recent research has resulted in the development of an electronic device for measuring tooth mobility, the Periotest, which uses an accelerometer to measure the resistance of the tooth to a force applied 16 times over a 4-second period by a small metal cylinder. This method employs a 60-point numerical scale ranging from −10 (ankylosed teeth or osseointegration, e.g. implants) to +50 (extreme mobility) and has the advantage of providing results that are reproducible and comparable with previous readings. Increasing or decreasing trends in mobility of individual teeth can thereby be more accurately assessed (Fig. 5.7).

 

 

 

Figure 5.7 The Periotest, for assessment of tooth mobility using an accelerometer.

 

ELECTRIC PULP TEST

 The objective of EPT is to stimulate intact A    δ nerves in the pulp–dentine complex by applying an electric current on the tooth surface. A positive result stems from an ionic shift in the dentinal fluid within the tubules causing local depolarization and subsequent generation of an action potential from intact A δ nerves. The electric pulp tester is a battery-operated instrument, which is connected to a probe that is applied to the tooth under investigation. It functions by producing a pulsating electrical stimulus, the initial intensity of which should be at a very low value to prevent excessive stimulation and discomfort. The intensity of the electric stimulus is then increased steadily at a pre-selected rate, and a note is made of the read-out on the digital display when the patient acknowledges a warm or tingling sensation. The read-out is not a quantitative measurement of pulp health, but simply provides evidence that the A δ fibres are sufficiently healthy to function. The electric pulp tester is technique sensitive and has a number of limitations. The requirements of an EPT are: an adequate stimulus, an appropriate application method, and careful interpretation of results. Tooth isolation during EPT is essential. Drying the enamel, placement of an interproximal plastic strip, and use of rubber dam can prevent the spread of electrical impulses to adjacent teeth or gingival tissue. Electric current can also be transferred between adjacent teeth through contacting metallic restorations. A conducting medium should also be used to ensure that maximum current passes from the electrode to the tooth surface. A laboratory study by Martin and co-workers concluded that the interface medium made no appreciable difference to either the voltage or the electric current transmitted. However, a more recent study did demonstrate that different media influence the responses gained from electric testing.

There are several considerations regarding optimal placement of the tester electrode. The response threshold is reached when an adequate number of nerve terminals are activated to attain, what is termed a summation effect. An area of high neural density should have a relatively fast and strong response, and requires the least electric current23. Therefore, the most desirable area of assessment in incisor teeth is at the incisal edge, where the enamel is thinnest or absent. The tester should be applied on the tooth surface adjacent to a pulp horn, as this receives the highest nerve density within the pulp. This position equates to the incisal third region of anterior teeth and the mid-third region of posterior teeth. The threshold for response may be influenced by the thickness of the enamel and dentine overlying the pulp. Thus, the response threshold for healthy teeth may be lowest in incisors, slightly greater in premolars, and greatest in molar teeth. A recent study has revealed that the optimum site for tester electrode placement on molars is on the tip of the mesiobuccal cusp.

 

TEST CAVITY PREPARATION

This test may serve as a last resort in testing for pulp vitality. It is only considered when the results of all other tests have proved inconclusive. Its value in clinical practice has been largely anecdotal as there is no evidence base to support its effectiveness. The test cavity is made by drilling through the enamel–dentine junction of an unanaesthetized tooth with good isolation. This may be achieved under rubber dam with a small round diamond bur in a high-speed handpiece with adequate coolant. The patient is asked to respond if any painful sensation is felt during the drilling procedure. If the patient feels pain once the bur contacts the sound dentin, the procedure is terminated and cavity is restored.

 

          LOCAL ANAESTHETIC TEST

When dental symptoms are poorly localized or referred, an accurate diagnosis is extremely difficult. Sometimes, patients may not even able to specify whether the symptoms are from the maxillary or mandibular arch. In such cases, and where pulp testing has proved inconclusive, an anaesthetic test may be helpful. The technique is as follows: using either infiltration or an intraligamentary injection, the most posterior tooth in the area suspected of causing the pain is anaesthetized. If pain persists once the tooth has been fully anaesthetized, the tooth immediately mesial to it is then anaesthetized, and so on, until the pain disappears. If the source of the pain cannot be even localized to the upper or lower jaw, an inferior alveolar nerve block injection is given; cessation of pain indicates involvement of a mandibular tooth. This approach has an advantage over a test cavity, which may incur iatrogenic damage.

LASER DOPPLER flOWMETRY

LDF is another non-invasive method for assessing blood flow in microvascular systems. The technique utilizes a beam of infrared light produced by a laser that is directed into the tissue. As light enters the tissue, it is scattered and adsorbed by moving red blood cells and stationary tissue elements. Photons that interact with moving red blood cells are scattered and frequently shifted according to the Doppler principle. Photons that interact with stationary elements are scattered but are not Doppler shifted. A portion of the light is returned to the photon detector, and a signal is produced. Because red blood cells represent the vast majority of moving objects within the tooth pulp, measurement of Doppler-shifted backscattered light is interpreted as an index of pulpal blood flow.

Laboratory Studies

Bacterial culturing is not routinely performed for oral lesions because of inherent problems with cross contamination. Viral culturing is performed with increasing frequency, especially in immunosuppressed patients with oral lesions of presumptive viral origin (see the image below). The Tzanck test, which looks for evidence of acantholysis in viral diseases (eg, herpes labialis) and autoimmune mucocutaneous diseases (eg, pemphigus vulgaris), is also occasionally used. Both tests unfortunately require that an intact blister be present, which often is not the case. Specific viral antigens can also be detected in biopsy specimens using various immunohistochemical techniques.Culturing of oral lesions is conducted most often when a viral etiology is being considered. Fungal cultures can also be taken; however, more cost-effective diagnostic procedures are available. Bacterial cultures are of limited value because of the difficulty in obtaining a pure specimen.

Fungal infections also are very common in the oral cavity. Potassium hydroxide digestion of a mucosal smear has classically been used to make that diagnosis; however, a dark-field or phase contrast microscope is necessary for in-office diagnosis. Smears can also be stained with one of several histochemical stains to reveal the presence of fungal organisms. These techniques often are more time consuming and expensive. Fungal culturing is of little value in most cases because of the slow growth rate of the organism. Rapid chair-side diagnosis is inexpensively achieved through the use of latex agglutination–based test kits developed for the diagnosis of vulvovaginal candidiasis (see the image below). These test kits are relatively inexpensive, highly accurate, and provide a diagnosis within 2 minutes.

 

Latex agglutination based diagnostic tests for Candida albicans have been available for use in gynecology for several years. While not specifically marketed for e in the diagnosis of oral candidiasis, such tests have proven to be very accurate, easy to use, and cost effective.

Other Tests

A number of diagnostic tests are routinely used in conjunction with a comprehensive oral examination to provide supplemental informatioecessary to arrive at a definitive diagnosis and institute treatment. As with any diagnostic process, the tests and procedures employed should be based on their diagnostic value, relative risks (eg, morbidity), and expense. Earlier diagnosis generally corresponds to earlier treatment and a better prognosis for the patient.

An oral soft tissue biopsy is one of the most commonly used diagnostic tests. While the oral soft tissue biopsy is relatively simple, individuals with some experience in performing intraoral procedures usually obtain it. Adequate lighting and suction are essential. Antibiotic premedication is essential for patients at risk for infective endocarditis and patients with prosthetic joint replacement. A vasoconstrictor (epinephrine) containing local anesthetic is preferred to control surgical bleeding and retard diffusion of the anesthetic into the surrounding tissues; however, in some patients, a vasoconstrictor is contraindicated because of hypersensitivity or other complicating factors. Topical lidocaine is routinely applied to the area of needle insertion to minimize the discomfort associated with needle insertion (see the image below).

Local infiltration anesthesia for intraoral biopsies generally is easy to administer. Use of topical anesthesia prior to needle insertion has not been shown to provide any significant relief of actual discomfort; however, it does decrease patient anxiety regarding local anesthesia. The selection of the specific biopsy site and biopsy technique is determined on the basis of the presumptive diagnosis and location of the lesion. For example, mucocutaneous diseases require an incisional biopsy to determine the specific diagnosis and appropriate treatment. In such cases, an incisional mucosal punch biopsy (3-4 mm in diameter) is sufficient (see the image below). Space-occupying lesions (eg, mucocele on the floor of the mouth) require a scalpel excision (see the second image below).

Biopsy punches come in a variety of sizes and in both reusable and disposable forms. Disposable biopsy punches are lighter and more easily manipulated than their metal counterparts. Most incisional intraoral biopsies can be performed with a 3- or 4-mm punch without suturing. Larger punches can be used for small excisional biopsies but usually require suturing for hemostasis.

Fig. instruments for oral biopsies

A No. 15 Bard-Parker blade, atraumatic forceps, and suture material are used for many oral biopsies and other soft tissue procedures. Take care to avoid the use of nonresorbable suture material for submucosal closure.

Because of the vascularity of this particular anatomic site, perform scalpel incisions in an anterior-posterior direction to minimize severing neurovascular structures. Avoid inclusion of the marginal gingiva in gingival biopsies for esthetic reasons, especially in the anterior maxilla. Handle small biopsy specimens with atraumatic Adson forceps rather than mouse-toothed forceps, which can damage the integrity of small mucosal specimens. The small size of most oral biopsy specimens requires that the specimen be placed in the appropriate fixative immediately after removal from the mouth. Ten percent neutral buffered formalin is used for most routine biopsies.

Fig. fixative solution

Tissue removed from the mouth must be placed in a fixative solution (except for the submission of material for frozen section in the hospital). For routine biopsies, 10% neutral buffered formalin is the fixative of choice. Consult the pathology laboratory for any anticipated special procedures to ensure that the tissue is handled properly.

The most recent development in oral biopsy technique is the oral mucosal brush biopsy, shown below. This technique uses a disposable brush to collect a transepithelial sampling of cells. The sample is screened by a neurally networked computer that is programmed to detect cytologic changes associated with premalignancy and squamous cell carcinoma. The specimen is reviewed by a pathologist for final diagnosis. This technique is ideal for determining the need for scalpel biopsy in benign-appearing oral mucosal leukoplakias.

The brush biopsy is an excellent procedure to screen benign-appearing oral mucosal leukoplakias to determine the need for subsequent scalpel biopsy. The procedure can be performed without anesthesia.

 

EXAMINATION  TYPES

The  four  different  types  of  dental  examinations  are discussed  in  the  paragraphs  that  follow.  To  ensure uniformity  in  nomenclature  and  definitions,  dental examinations are classified by type.

 

TYPE  1,  COMPREHENSIVE EXAMINATION

This  is  the  ideal  examination,  for  it  is  the  most extensive  dental  examination.  The  dentist will  performa comprehensive hard and soft tissue examination that includes:  oral  cancer screening examination;  mouth-mirror,  explorer,  and  periodontal  probe  examination;adequate  natural  or  artificial  illumination;  pano-graphic  or  full-mouth  periapical,  and  posteriorbitewing  radiographs;  blood  pressure  recording;  andwhen indicated, percussive, thermal and electrical test,transillumination,   and   study   models. Included  are those lengthy clinical evaluations required to establisha complex clinical diagnosis and the formulation of atotal treatment plan. For example: treatment planningfor  full-mouth  reconstruction;  determination  of  the etiology  or  differential  diagnosis of  a  patient’s chief complaint,  such  as  temporomandibular  joint  (TMJ)

dysfunction and associated oral facial pain; or lengthy history taking relative to determining a diagnosis, or in-processing examination for officer candidates.

 

TYPE 2, ORAL EXAMINATION

Comprehensive hard and soft tissue examination, which  will  include:  oral  cancer  screening  examination; mouth-mirror,   explorer,   and   periodontal   probe examination;   adequate   natural   or   artificial   illumination;   appropriate   panographic   or   intraoral radiographs as indicated by the clinical examination; and   blood   pressure   recording.   An   appropriate treatment   plan   will   be   recorded.   This   type   is   the routine examination, which is normally done only one time  per  treatment  regimen  per  patient,  unless circumstances warrant another complete examination.

 

TYPE 3, OTHER EXAMINATION

This   examination   consists   of   diagnostic procedures  as  appropriate  for:  consultation  between

staff  or  staff  residents;  observation  where  no  formal consult   is   prepared;   certain   categories   of   physical examinations;  and  emergency  oral  examinations  for evaluation   of   pain,   infection,   trauma,   or   defective restorations.

 

TYPE  4,  SCREENING  EVALUATION

This  type  of  examination  consists  of  a  mouth-mirror and explorer or tongue depressor examination with whatever illumination is available. This category includes  the  initial  dental  processing  of  recruits without  necessarily  being  examined  by  a  dentist  or other   screening   procedures.   A   qualified   dental assistant  or  dental  hygienist  may  perform  a  type  4 examination.

 

OCCASIONS  FOR  DENTAL EXAMINATIONS

Dental   examinations   are   performed   on   various occasions. The type of the examination performed will depend  on  what  the  patient  needing  an  examination requires (i.e., retirement, annual, etc.).

 

ACCESSION

All Navy and Marine Corps personnel who enter the   military   service   will   have   a   dental   record established  with  an  accession  examination  and radiographs.

 

PERIODIC  DENTAL  EXAMINATIONS

Dental  examinations  of  all  active  duty  personnel  must  be  conducted  annually and  on  other  appropriate  occasions  to  establish  the need  for  dental  treatment  and  verify  dental  records. Periodic   dental   examinations   access   the   readiness status   of   active   duty   personnel.   The   annual examination  should  normally  be  a  type  2  examination.

 

PERIODICITY  OF  MEDICAL EXAMINATIONS  (PHYSICALS)

As   a   part   of   each   member’s   medical   physical examination, a dentist must examine the member and record   the   results   on   the   Report   of   Medical Examination,  SF-88  (covered  later  in  this  chapter). Entries  are  also  made  on  the  member’s  EZ603,  and filed in the NAVMED 6150/21-30. All active duty members and reservists will have medical examinations completed as follows: Upon entry to enlisted or commissioned active duty

o      At intervals of 5 years through age 50

o      At intervals of 2 years through age 60

o      Annually after age 60