The aim of this study is to evaluate the Clinical performance of alternating current impedance spectroscopy (CarieScan PRO) in comparison with digital radiograph and ICDAS-II in detection of occlusal carious lesions.

The visual examination is routinely used for detecting caries in dental clinics and was also used in recent studies comparing the efficacy of various visual aids. It has the benefit that it is quick and easy to perform, does not need expensive equipment, and can be completed without unnecessary radiation or fluorescence (Ismail, et al., 2007). In the current study, ICDAS-II was set as "gold standard" due to validated relationship between its codes and the histological depth of a carious lesion as in many other studies. In addition, several studies have shown good reproducibility and accuracy of ICDAS-II for caries detection in permanent teeth especially caries lesions in the outer half of the enamel (Gugnani, et al., 2010). Bitewing radiographs are used to determine the depth of caries involvement. Most often, bitewing examination is affiliated with the diagnosis of interproximal caries. It is strongly recommended that these radiographs be used in the diagnosis of occlusal caries into dentin (Pitts NB et al., 1991).

Inclusion Criteria of teeth:

• Posterior teeth with dark shadow on occlusal surface.
• Vital upper or lower posterior teeth with no signs of irreversible pulpitis.
• Intact contact with opposing teeth.
• Teeth with no previous restorations in other surfaces.

Exclusion criteria of the teeth:

• Periapical pathology or signs of pulpal pathology.
• Tooth hypersensitivity.
• Possible prosthodontic restoration of teeth.
• Heavy occlusion and occlusal contacts or history of bruxism.
• Severe periodontal affection.