The purpose of this study is to assess the effectiveness of nitrous oxide/oxygen administration in reducing the discomfort of intranasal midazolam administration for moderate sedation for dental procedures.

This study will determine the effectiveness of two different concentrations of nitrous oxide for reducing the pain of intranasal midazolam when given for subjects already planned for moderate sedation for completion of dental procedures in the pediatric dental clinic. Moderate dental sedation is useful because it helps relieve anxiety and make the dental procedure less memorable and more comfortable for the patient. Sedation appointments typically go smoothly when the patient is calm rather than when the patient is upset. Giving midazolam through the nose can be painful and the dental provider risks upsetting a patient and causing the sedation appointment to fail. Therefore, the goal of this study is to test whether nitrous oxide administration is effective in reducing the pain from intranasal midazolam administration. The effectiveness will be measured by the primary outcome of heart rate pre- and post- midazolam administration for the two randomly assigned study arms. The first study arm will be given 30% nitrous/70% oxygen and the second study arm will be given 70% nitrous/30% oxygen prior to the midazolam administration. The secondary outcome will compare subject, dental provider, and the parent/guardian answers to questions regarding the subject's experience pre- and post- midazolam administration. The investigators hypothesize lower changes in heart rate and less pain reported following midazolam administration in subjects given 70% nitrous oxide.

Inclusion Criteria:

• Patients selected to undergo moderate sedation at the Children's Hospital Colorado Dental Clinic
• Subject must have visited the dental clinic within 4 months of their sedation appointment for a regular dental examination
• Subject must have a well-child visit with their primary care physician within the last 12 months prior to their sedation appointment
• Child must fall between the ages of 3 to 8 years old
• Child must be healthy, American Society of Anesthesiologists scale I or II
• Children under 4 years will be asked to count and explain the instrument before enrollment.

Exclusion Criteria:

• Upper respiratory illness (URI) symptoms less than 4 weeks before sedation appointment
• American Society of Anesthesiologists scale III or IV
• Children with special needs including intellectual disability, congenital malformations, chronic conditions
• Chronic lung disease
• Cyanotic heart disease
• Children with anatomic airway abnormalities or moderate to severe tonsillar hypertrophy
• Any contraindications to nitrous oxide use including: Chronic obstructive pulmonary diseases, current upper respiratory tract infections, recent middle ear disturbance/surgery, severe emotional disturbances or drug-related dependencies, previous treatment with bleomycin sulfate, methylenetetrahydrofolate reductase (MTHFR) deficiency, cobalamin (Vitamin B12) deficiency
• Allergy or hypersensitivity to nitrous oxide or midazolam

There is no plan to share individual personal data with other researchers.

Sedation provider who will administer the pain scale tests and the participant will be masked to the subject's assigned study arm (30% or 70% nitrous oxide with midazolam). The attending pediatric dentist and dental assistant will not be blinded for patient safety.