**4.3.4 LED technology (Midwest Caries I.D.)**

Recently, another device for caries detection was developed on LED technology - Midwest Caries I.D. – (DENTSPLY Professional, York, PA, USA) (Figure 9). The handheld device emits a soft light emitting diode (LED) between 635 nm and 880 nm and analyzes the reflectance and refraction of the emitted light from the tooth surface, which is captured by fiber optics and is converted to electrical signals for analysis. The microprocessor of the device contains a computer-based algorithm that identifies the different optical signature (changes in optical translucency and opacity) between healthy and demineralized tooth (Strassler and Sensi, 2008).

Fig. 9. Midwest Caries I.D. device and the standard for calibration procedure.

The demineralization leads to a change in the LED from green to red with a simultaneous audible signal, which is directly related to the severity of caries lesions. According to the manufacturer, when there is a change in the optical translucency and opacity of the dental tissues, the emitted green light changes to red and an audible signal could be heard. The faster the signal, the deeper the lesion. In the literature, there is only one published study which evaluated the Midwest Caries I.D. in vitro performance for occlusal caries detection (Rodrigues et al., 2011). In this study, the device presented the same cut-off limits for cariesfree sites and enamel caries. This means that the Midwest Caries I.D. was not able to differentiate enamel lesions from sound surfaces.

#### **4.3.5 Fiber-optic transillumination (FOTI) and digital imaging fiber-optic transillumination (DIFOTI)**

Fiber-optic transillumination (FOTI) and digital imaging fiber-optic transillumination (DIFOTI) have been introduced to improve early detection of carious surfaces and have been accepted by clinicians as a supplementary tool during clinical examinations.

Traditional and Novel Caries Detection Methods 123

Fig. 11. (A) Digital imaging fiber-optic transillumination (DIFOTI). (B) Tip for occlusal

Over the last decades, the relationship between the extent of caries in teeth and electrical resistance has been investigated. It is possible to assess caries lesions considering the various parameters affecting the electrical measurements of teeth, such as porosity, surface area of the contact "electrode", the thickness of the enamel and dentin tissues, hydration of the enamel, temperature, ionic content of the dental tissue fluids, and the maturation time of the

The studies on electrical caries monitor device (ECM) (Figure 12) have assessed these parameters in a "site-specific" or "surface specific" mode. This method has shown different results of reproducibility and validity (Huysmans et al., 2005; Kühnisch et al., 2006). Some in vitro studies indicated that the presence of stain is a confounder for ECM measurements. Besides, the different cut-off limits for enamel and dentin caries lesions may be needed for stained teeth (Côrtes et al., 2003; Ellwood & Côrtes, 2004). Therefore, its indication in the clinical practice is still uncertain. Further in vivo studies are necessary in order to make this

surfaces.

**4.3.6 Electrical caries monitor (ECM)** 

technology useful in the practice.

Fig. 12. Electrical caries monitor (ECM).

tooth in the oral environment (Neuhaus et al., 2009).

FOTI (Figure 10) device is a practical, easy, fast and inexpensive method of imaging teeth in the presence of multiple scattering. It is based on the changes in the scattering and absorption phenomenon of light photons that increases the contrast between sound and enamel caries. In other words, results from a local decrease of transillumination owing to the characteristics of the carious lesion. The illumination is delivered via fiber-optics from a light source to a tooth surface. The light propagates from the fiber illuminator across tooth tissue to non-illuminated surfaces. The resulting images of light distribution are then used for diagnosis. Its transmission can be observed either in the opposite side or in the occlusal surfaces, when molars and premolars are analyzed. As light scattering is higher in the demineralized enamel, it is possible to see the lesion as a dark area or a shadow. Besides, carious dentin appears orange, brown or grey underneath the enamel. This can help on the differentiation between enamel and dentin lesions. However, it has been show that FOTI diagnosis by naked eye can be subject to great inter- and intra-examiner variation (Neuhaus et al., 2009).

Fig. 10. Fiber-optic transillumination (FOTI).

To overcome the variability dilemma in FOTI, a new method has been tested. DIFOTI (Figure 11) is a method which employs digital image processing for quantitative diagnosis and prognosis in dentistry. It is based on light propagation just below the tooth surface and can be used to determine lesion depth. It uses fiber-optic transillumination of safe visible light to image the tooth. In this system, light delivered by a fiber-optic is collected on the other side of the tooth by a mirror system and recorded with a CCD imaging camera, instantaneously. Thus, DIFOTI images can be acquired in repeatable fashion by maintaining adjustment of a number of imaging control parameters. Then the acquired information is sent to a computer for analysis with dedicated algorithms, which produce digital images that can be viewed by the dentist and patient in real time or stored for later assessment. In addition, this system can use digital image processing methods to enhance contrast between sound and carious tissues and to quantify features of incipient, frank and secondary caries lesions on occlusal, approximal and smooth surfaces. It can also be used to detect other changes in coronal tooth anatomy, such as tooth fractures and fluorosis. DIFOTI presents higher sensitivity in detection early lesions when compared to the radiographic examination and has potential for quantitative monitoring of selected lesions over a period of time (Bin-Shuwaish et al., 2008; Young & Featherstone, 2005).

FOTI (Figure 10) device is a practical, easy, fast and inexpensive method of imaging teeth in the presence of multiple scattering. It is based on the changes in the scattering and absorption phenomenon of light photons that increases the contrast between sound and enamel caries. In other words, results from a local decrease of transillumination owing to the characteristics of the carious lesion. The illumination is delivered via fiber-optics from a light source to a tooth surface. The light propagates from the fiber illuminator across tooth tissue to non-illuminated surfaces. The resulting images of light distribution are then used for diagnosis. Its transmission can be observed either in the opposite side or in the occlusal surfaces, when molars and premolars are analyzed. As light scattering is higher in the demineralized enamel, it is possible to see the lesion as a dark area or a shadow. Besides, carious dentin appears orange, brown or grey underneath the enamel. This can help on the differentiation between enamel and dentin lesions. However, it has been show that FOTI diagnosis by naked eye can be subject to great inter- and intra-examiner variation (Neuhaus

To overcome the variability dilemma in FOTI, a new method has been tested. DIFOTI (Figure 11) is a method which employs digital image processing for quantitative diagnosis and prognosis in dentistry. It is based on light propagation just below the tooth surface and can be used to determine lesion depth. It uses fiber-optic transillumination of safe visible light to image the tooth. In this system, light delivered by a fiber-optic is collected on the other side of the tooth by a mirror system and recorded with a CCD imaging camera, instantaneously. Thus, DIFOTI images can be acquired in repeatable fashion by maintaining adjustment of a number of imaging control parameters. Then the acquired information is sent to a computer for analysis with dedicated algorithms, which produce digital images that can be viewed by the dentist and patient in real time or stored for later assessment. In addition, this system can use digital image processing methods to enhance contrast between sound and carious tissues and to quantify features of incipient, frank and secondary caries lesions on occlusal, approximal and smooth surfaces. It can also be used to detect other changes in coronal tooth anatomy, such as tooth fractures and fluorosis. DIFOTI presents higher sensitivity in detection early lesions when compared to the radiographic examination and has potential for quantitative monitoring of selected lesions over a period of time (Bin-

et al., 2009).

Fig. 10. Fiber-optic transillumination (FOTI).

Shuwaish et al., 2008; Young & Featherstone, 2005).

Fig. 11. (A) Digital imaging fiber-optic transillumination (DIFOTI). (B) Tip for occlusal surfaces.
