Fiber optic transillumination (FOTI) is a method for diagnosing carious dentin lesions in the proximal surfaces. As a non-invasive and practical method, FOTI is a useful addition to visual caries diagnostics.
In both the deciduous and permanent dentition, it is difficult to visually diagnose caries in the proximal surfaces (in the interdental spaces) as long as the surfaces of the teeth have not yet broken down. More than half of all proximal caries lesions remained undetected without further diagnostic measures. In addition to invasive radiographic caries diagnosis, FOTI, as a noninvasive method, is able to detect hidden dentin caries (caries of the dentin) in the interdental spaces at a stage when the surfaces of the teeth have not yet broken down, i.e., the teeth are less deeply destroyed.
Indications (areas of application)
- The FOTI is suitable for the diagnosis of hidden proximal dentin caries (caries of the dentin, starting from the surfaces in the interdental spaces) in the permanent dentition. In combination with the bitewing radiograph, it provides diagnostic confidence in radiographically questionable dentin findings, since a positive radiographic finding can be established only after demineralization of the dentin and thus “lags” the clinical findings by several weeks.
- The procedure can be used reasonably for close-meshed caries progression control.
- Due to the refractive properties of deciduous teeth, the procedure is not as meaningful here as in the permanent dentition.
Contraindications
The procedure is not suitable for diagnostic detection of proximal enamel lesions. For this purpose, radiographic diagnosis by bitewing radiographs should be preferred.
Before the examination
Prior to the examination, air-drying of the teeth in the area to be examined is performed.
The procedure
The procedure takes advantage of the different refractive properties of healthy and decayed tooth structure. Cold light probes are used for fiberoptic transillumination. In cold light, the infrared portion of the light spectrum and thus the heat generation is greatly reduced.
Probe models with small light exit windows and also wedge-shaped beveled light probe tips (e.g. Göttingen model) are particularly effective for FOTI, as these can be inserted further into the approximal space between the adjacent teeth and fit the tooth surfaces better.
The light probe is positioned from buccally or orally (from the cheek or oral cavity) in the area of the interdental space (space between the teeth) and gently swiveled back and forth there. If an approximal lesion (interdental caries) is present, it will appear as a dark area within the otherwise brightly transilluminated tooth when viewed from occlusal (from the occlusal surface), and its position will remain constant as the probe is swiveled.
Potential complications
Enamel cracks, infractions (fracture lines) or enamel hypoplasia (enamel formation disorders) also affect the refractive index of the tooth structure. Therefore, they must be differentiated from carious changes by differential diagnosis.
