Response characteristics of the cat somatosensory cortex following the mechanical stimulation to endodontically treated teeth with overextension

Abstract The overextension of filling materials may take place accidentally during an endodontic root canal treatment. Previous studies to understand the correlation between overfilling and paresthesia of teeth were inconsistent. In this study, an intrinsic signal optical imaging technique was employed as the objective tool to compare the response characteristics of the cat somatosensory cortex following mechanical stimulation applied to endodontically treated teeth with overextension (ETTWO) and natural teeth. Based on the evoked cortical response, the signal strength of the ETTWO was found to be significantly higher than that of the natural teeth. However, the tactile threshold of the ETTWO was significantly lower than that of the natural teeth. It was concluded that the tactile function of ETTWO is more sensitive than that of natural teeth, and that the overextension of filling materials can cause hyperesthesia of teeth after root canal treatment.