The hidden caries was initially described as dentin cavitary progressive lesions with healthy or minimally demineralized enamel that can be identified with radiographic investigations. Because of the initial clinical discreet evolution of this pathology, the subjective signs that draw patients’ attention to the affected tooth appear only in advanced stages of dentinal destruction. Considering the fact that this caries is often detected by chance when radiologically investigating the neighboring teeth, there is a very high probability of detection in a highly advanced stage of evolution towards the dental pulp. The aim of this paper is to evaluate the clinical and statistical distribution of this pathology detected on 312 patients from both genders that came for treatment asking for a second opinion during a period of 5 years. An initial clinical examination was first accomplished for each patient who was also asked to answer to a questionnaire regarding his dental history. For each targeted tooth was performed a radiographic investigation and the radiographic results and the anamnesis data were noted in a treatment sheet especially designed for this study. The results of the study were finally gathered and they represented the basis for the discussions upon the causes that led to misdetection of these caries. The conclusions indicated that dentists’ theoretical deficiencies in detecting and diagnosing this pathology always led to a wrong approach of the case and conducted to a non-realistic treatment plan.