A Summary

Visual-Tactile Caries Diagnosis

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). This approach works by observing abnormalities in tooth colouration and structure as well as the "stickiness" of the explorer to the lesion through probing. There has been much controversy because of this, mainly because forceful probing may serve to prevent remineraliztion on a non-cavitated lesion. Moreover, this method is highly subjective and dependent on the quality of the practitioner. The visual-tactile approach is usually the very foremost fundamental method to caries detection and needs to be coupled with other diagnosis methods to complete a thorough check-up.


In order to detect dental caries, both a careful clinical examination and radiographic examination are necessary. A dental examination for caries cannot be considered complete without radiographs. The dental radiographs enables the dental professional not only to evaluate the extent and severity of a carious lesion seen clinically but also to identify carious lesions that are not visible clinically. In this topic, we have covered the common types of radiography used for the detection of caries and the techniques and common errors when taking a radiograph. This will provide us with information that will help us to identify the different types and extent of caries through radiographs. Reseach and development of new and upcoming radiographic technologies such as subtraction radiography are being done to improve existing methods and their effectiveness.

Fiber-Optic Transillumination (FOTI)

Fiber-optic transillumination (FOTI) is an enhanced visual technique that uses the principle of illuminating teeth to detect the presence of caries. The principle behind transilluminating teeth is that demineralized areas of enamel or dentine scatter light more than sound areas. Incipient caries appear as darker areas in the resultant images, which are obtained during screening. FOTI can be used for detection of caries on all surfaces, although it is more useful for proximal lesions. FOTI is also good for early detection of caries. An interesting and useful concept is that despite the low sensitivity of FOTI, the consistently high specificity allows for the ability of FOTI to correctly diagnose caries based on exclusion.

Digital Fiber-Optic Transillumination (DIFOTI)

Digital Imaging Fiber-Optic Transillumination (DIFOTI) is a technique that builds on Fiber-Optic Transillumination (FOTI). It applies the same principle of caries detection via illumination but with an additional grey scale camera to capture the images taken during inspection. The camera attached to the mouthpiece of the DIFOTI instrument captures images either from the lingual/buccal side (for proximal and smooth surface caries) or from the top of the tooth (for occlusal caries). The images can be stored and reviewed at subsequent visits. Since demineralized enamel or dentine scatter light more than sound areas, incipient caries appear darker in the resultant images. The DIFOTI technique has superior sensitivity to conventional radiological methods for the detection of approximal, occlusal and smooth surface caries. DIFOTI can be used for early detection of caries. It is rapid and non-invasive, and patients are encouraged to take on a preventive approach since they are now able to examine the demineralized enamel and condition of their teeth. However, DIFOTI still relies on the clinician’s subjective analysis to confirm a carious lesion. Hence, future research can be done to develop a method to quantify the results and determine the depth of lesions.

Electrical Conductance

The basis of using electrical conductance to detect carious lesions lies in the fact that soluble electrolytes and fluid percolate into these caries found in the enamel and dentine layer and reduce the bulk resistance of the tooth when an electric current is run through it. An electronic caries monitor (ECM) or an electrochemical impedence spectroscopy (EIS) is used to detect these minute deviations from normal electrical conductivity of teeth and detect regions of the tooth which has lesions in their early stage. The method involves the patient holding a contra electrode in the hand while a probe is placed on the surface or site of interest on the tooth. By releasing a fixed current of known voltage, the resistance of the tooth can be obtained. This method is effective both in vitro and in vivo but its application is mostly limited to the former due to the tedious process of carrying out the procedure. The safety and effectiveness of in vivo application of this diagnostic method is highly debated, and the consistent disparity of results retrieved due to insufficient and unpredictable probe contact also raised concerns over the precision of experimental results obtained and the significance of the margin of error.

Laser Fluorescence And Quantitative Light Fluorescence

The working principles of this method of diagnosis is to utilizespecific wavelengths of light to identify carious lesions. For laser fluorescence, the method involvesinducing fluorescence inbacteria byproducts while natural fluorescence of enamel is utilized in QLF.These methods are fascinating and worth investigating because they are non-invasive and can detect relatively small lesions early. However, there may be some controversy between theclaimed sensitivity of the diagnostic methods by the companies producing them and the actual detection capability of these methods, and hence all claims should be taken with a pinch of salt.

Towards The Future: Other New And Emerging Technologies

No single diagnostic method is perfect, and each method has its own limitations and areas of effectiveness. Having more alternatives in diagnostic methods provides practitioners with more options for specific situations, with greater sensitivity and specificity for early caries detection. Hence, it is crucial that new technologies are constantly being researched and developed in order to provide more effective diagnoses and treatment plans. It is particularly fascinating to study some of the latest methods undergoing research and development, and the working principles behind them. Some of these include Infrared Thermography, Ultrasound Technology, Optical Coherence Tomography, and Polarised Raman Spectroscopy. It is interesting to see how the fields of Dentistry, Biochemical Engineering, and Physics are able to merge together in the development of these emerging technologies. Certainly, in due time and with more research and trials, we will be able to see some of these being used clincally in the near future.

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Electrical Conductance | Laser Fluorescence And QLF | Towards The Future: Other New And Emerging Technologies | A Summary


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