Visual-Tactile Caries Diagnosis

Brief Description

This is the most conventional method of dental examination, where the dentist detects the presence of caries and diseases in the mouth via sight (visual inspection) or touch (usually using a dental explorer).


Working Principles

Caries occur when the tooth surface is damaged due to prolonged exposure to acids. These acids can arise from bacteria, or from our diet. The destruction of the tooth structure (dentine, enamel, and finally the pulp) leads to irreversible pathological changes in the tooth, which can be detected by visual inspection or by the sense of touch. Ideally, dentists should look out for good visual indicators that involve features which are purely associated with caries itself. This is to prevent misdiagnosis and confusion over the patient’s oral health condition.

The initial stage of caries is the dissolution of surface enamel crystals, leading to a change in its optic behaviour. Healthy enamel should be slightly translucent, but partially dissolving enamel is opaque. Dissolving enamel is more porous due to the acidic effect on the tooth, and hence scatters more light to give rise to it its opaque appearance.
The difference between air’s refractive index (1.00) and that of hydroxyappatite (1.66) (the substance which enamel is made of) is larger than that between hydroxyappatite and water (1.33). This means that a mildly demineralised tooth covered with water might not appear opaque, but might appear so when it is air dried. In other words, a lesion that has to be dried before opacities are observed has loss less minerals than a tooth which appears opaque even when wet (Ekstrand, 2004). This highlights the importance of drying all teeth during a dental examination, so as to detect caries in their early stages. Early stage caries (before cavitation and the loss of tooth structure occurs) are reversible, and early detection plus excellent oral hygiene might lead to a reversal of the cavitation process. (Ismail, 2004)


(Picture Source: Pesqui, Odonto. 2003)

The demineralization of dentine weakens tooth structure and exposes dentine, giving rise to the “tackiness” found on carious teeth. Dentists make use of this tactile property in the diagnosis of caries as well.

Lastly, there are also colour changes that occur as teeth decay. The crowns of such teeth can appear black or brown, while carious roots might have a yellow/orange/tan/light brown appearance.


The Method



A video showing a basic dental examination, not exclusively limited to visual-tactile caries diagnosis.
(Video source: Gordon, 2009)

First, all teeth are cleaned to remove plaque, calculus and other foreign materials. The teeth should also be dry and well illuminated. With the help of special tools, the dentist proceeds to visually inspect the tissue inside the mouth, including checking for signs of oral cancers. All exposed surfaces of the teeth (lingual, buccal, occlusal) are inspected with the help of a dental mirror. Using the dental probe, the bumps and valleys on the surface of the tooth are gently felt. At the same time, the dentist looks out for indications of caries/enamel dissolution and demineralization. Some of them are listed below:

- “Tackiness” on the surfaces of the tooth. The probe sticks to surfaces of the tooth when a little pressure is applied, and a definite pull is required to remove the probe (resistance in removing probe known as a tugback). This method is no longer used since it may result in the cavitation of initial lesions which may be reversed.

- Discontinuity of the enamel

- Discolouration:

o White spots on clean, dry, illuminated teeth

o Yellow tinge due to erosion of enamel and greater exposure of underling dentine

o Black/brown areas, especially along pits and fissures

o Yellow/orange/tan/light brown appearance of roots

- Penetration of tooth surface by explorer. This method is no longer advised since it may cause damage to reversible initial lesions.

- Loss of translucency and lustre of tooth surface

- Exposure of dentine and/or pulp

- Rough surfaces on otherwise smooth tooth surfaces (etc cusps, buccal/lingual surfaces of posterior teeth)
(Ismail, 2004)

Effectiveness

"Once the teeth are separated, a good eye, experienced in this kind of diagnosis, and the mirror will usually be sufficient" (Anonymous, 1869) Visual-tactile diagnosis is a relatively fast, cheap and reliable means of caries diagnosis. Research done by Ekstrand et al. (1997) and Ricketts et al. (2002) shows the effectiveness of this type of diagnosis.




Using wisdom teeth that were scheduled for extraction, these teeth were classified according to the depth and type of caries activity using the criteria in the table below. A histological examination was then done on the extracted teeth. The result was that Kappa values (which can range from -1 to +1) ranged between 0.74 and 0.85 for intra-examiner examinations, and between 0.78 and 0.80 for inter-examiner examinations.

Kappa value: chance of agreement between 2 sets of data. In this case, it refers to the degree of agreement of caries classification between the visual-tactile method of diagnosis, and the histological findings.

In another 3 year study done by Machiulskiene et al.,2001, inter-examiner reliability, which was tested each year, ranged from substantial to excellent. These studies show that visual-tactile diagnosis is sufficiently effective in diagnosis of progress of caries in the oral environment. (Ekstrand, 2004)


(Table source: Ekstrand, 2004)




However, there are limitations associated with this type of diagnosis.

1. Caries scripts are mental images dentists have of the patterns in caries formation. These abstract images are formed during dental school, and are continuously changed as the dentist gains experience. When the dentist is faced with a clinical presentation that matches his/her personal caries scripts, it will then lead the dentist to decide on his/her treatment plan. As these caries scripts are highly susceptible to personal bias, non-tangible and difficult to describe, this leads to a large discrepancy of caries scripts across dentists. This is one factor that explains why different dentists make can lead to varying caries diagnosis of a patient after doing a visual-tactile examination, as their caries scripts differ. (Heidmann, Nyvad. 2006)

2. Cavities are often located at the bottom of deep fissures or in their walls and difficult to detect during visual examination and with the aid of a probe. It can be difficult to determine the depth and location of the cavity from pure visual inspection, especially if the cavity is located on the approximal and root surfaces of the tooth. (Tomasik, Weyna, Tomasik, Lipski, Woźniak, Durham 2005)

Picture source: Dental caries. Retrieved from http://en.wikipedia.org/wiki/Dental_caries

Picture A shows only a small, seemingly harmless black spot on the occlusal surface of the molar. However, an X-ray (picture B) and the removal of surface enamel (picture C) reveal a large cavity on the mesial tooth surface . Picture D shows the tooth after all carious material has been removed.

3. Visual examination of occlusal surfaces that are intact to the naked eye generally has a sensitivity of as 30%, but can rise with experience and proper training. Specificity higher than 80% and sensitivity of 60% can also be achieved in the diagnosis of borderline dentine caries lesions. (McComb & Tam ,2001)

4. The presence of a stain does not necessarily mean the presence of caries. A lesion which appears brown and shiny suggests dental caries was once present but the demineralization process has stopped, leaving a stain. Tobacco use, certain foods (coffee, tea, wines) and certain medications (chlorhexidine, Tetracycline) can also cause staining, leading to misdiagnosis. (McComb & Tam ,2001) Lussi concluded in the book “Comparison of different methods for the diagnosis of fissure caries without cavitation” that
“using these [discolouration] parameters for diagnosis of dentinal caries,
at least 55% of sound teeth would be misclassified (false positive).”

5. A “sticking” probe might be due to the anatomical features of the tooth and does not necessarily indicate decay. Using the probe can also potentially damage tooth structure, and even lead to the implantation of certain organisms that can even enhance the decay process. (McComb & Tam ,2001)

6. White spots appearing on the tooth are not an exclusive observation associated with demineralization. They could also be the result of fluorosis (too much fluoride in the tooth) . Hence, extra care must be taken to prevent misdiagnosis. The white spots appearing on the tooth should also be accompanied by other indications of demineralization, such as roughness of the tooth surface, softness of the tooth structure or a loss of luster. The outline of the white spot should also be taken into consideration. For example, white streaks are more likely to be associated with fluorosis instead of demineralization. (Ismail ,2004)

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References

1. Enamel Fluorosis. American Academy of Pediatric Dentistry. Retrieved from http://www.aapd.org/publications/brochures/fluorosis.asp.

2. Dental probes & explorers. Retrieved from http://medical-tools.com/dental/probe-explorers1.php.

3.Ekstrand, K. R. (2004). Improving clinical visual detection--potential for caries clinical trials. J Dent Res, 83 Spec No C, C67-71.

4. Naba’a, L. Advanced methods of quantification of occlusal caries. Retrieved from http://www.the-o-zone.cc/HTMLOzoneF/pdf/AdDiag01.pdf.

5. Fejerskov, O., & Kidd, E. (2008), Dental Caries: The Disease and Its Clinical Management 2nd edition. Wiley-Blackwell.

6. Gordon, J. (2009) The dental comfort zone. http://www.dentalcomfortzone.com/media.php.

7.Baelum, V., Heidmann, J., & Nyvad, B. (2006). Dental caries paradigms in diagnosis and diagnostic research. Eur J Oral Sci, 114(4), 263-277.

8. Ismail, A. I. (2004). Visual and visuo-tactile detection of dental caries. J Dent Res, 83 Spec No C, C56-66.

9. McComb, D., & Tam, L. E. (2001). Diagnosis of occlusal caries: Part I. Conventional methods. J Can Dent Assoc, 67(8), 454-457.

10.Scheid, R.C., & Woelfel, J B. (2007). Woelfel's dental anatomy: its relevance to dentistry, 7th edition. Lippincott Williams & Wilkins.

11. Summit, B.J. (2001) Fundamentals of Operative Dentistry: A Contemporary Approach, 2nd edition. Illinois: Quintessence Publishing.

12. Tomasik, M. (2005). Comparison of visual and laser examination of first permanent molars in patients aged 6-7 years. Retrieved from http://www.dur.ac.uk/anthropology.journal/vol12/iss2-3/tomasik1/tomasik1.html.