Previous Trigemino-Cardiac Reflex(TCR) related studies reported that stimulation of trigeminal nerve induces trigeminal nerve reflection, and then causes blood pressure rapidly decreasing. Finally, sudden blood pressure decreasing results in syncope. Clinical data has been collected and analyzed in the past four months, and the primary results showed significantly difference. This phenomenon may be probably observed in other dental treatments. Hence, the objective of this study is to remind clinical dentists to monitor patients' physical conditions when conducting root canal relevant treatments and to avoid situations such as syncope, and reduce medical disputes and benefit dentists and patient as a result. In the recent year, syncope often occurs during denture procedures. The value of this study will inform clinical dentist to notice risk of dental relative treatments. In addition, it will improve patients' safety.