Intravenous sedation was used for dealing with transient hypertension, so-called white-coat hypertension, before dental treatment. Midazolam used as a sedative also has antianxiety effect, and the mechanism is guessed that it minimizes patients' stress, resulting in the stability of blood pressure. The purpose of this randomized controlled trial (RCT) is to evaluate the effect of low dose of midazolam on blood pressure and anxiety scale in white-coat hypertensive dental patients.

Inclusion Criteria:

SBP>=140mmHg or DBP>=90mmHg measuring when the patient sits on dental chair and has settled down for 5 minutes among dental outpatients scheduling intravenous sedation with American Society of Anesthesiologists physical status I or II.

Exclusion Criteria:

1. Uncontrolled or unstable hypertension
2. Secondary hypertension such as hyperthyroidism and pheochromocytoma
3. Taking sympathomimetic drugs
4. Contraindication of midazolam such as myasthenia gravis and acute narrow-angle glaucoma
5. A pregnant woman or during lactation period
6. Psychiatric disorder such as schizophrenia
7. Not having intelligence enough to read, understand and write a Japanese version of STAI
8. Judged unsuitable by a researcher