This study will evaluate effectiveness of a urethane dimethacrylate (UDMA)-quaternary ammonium methacrylate (K18) resin (UDMA-K18) smooth surface sealant to prevent biofilm attachment to tooth surfaces thereby eliminating the possibility for the tooth to be demineralized. The hypothesis is that UDMA-K18 containing smooth surface sealant will be more effective at reducing enamel demineralization than the UDMA control or no treatment.

Esthetics is a motivating factor to seek orthodontic treatment. However, if oral hygiene is inadequate during fixed appliance wear, unsightly white spot lesions (WSL) may develop. WSLs are areas of enamel demineralization that develop due to microbial assault that manifest as white, chalky opacity on the enamel. Urethane dimethacrylate (UDMA) can be modified to produce an antimicrobial compound, UDMA-K18, that has been proven to decrease microbial attachment in-vitro. (Sticker 2016) The use of a UDMA-K18 containing sealant may help to eliminate the development of WSLs around orthodontic brackets.

This study will place experimental or control smooth surface resins on teeth that are scheduled to be extracted for orthodontic reasons. These teeth are typically bicuspids that are to be extracted to create room for the orthodontic movement of teeth. These teeth are usually not extracted at the advent of first orthodontic bracket bonding but are extracted about 30 days later. The design of this study is to place sealants on those teeth (or as control, no sealant) and evaluate the teeth after they have been extracted.

Design: The study is a prospective, paired randomized control trial for which treatment (no sealant, UDMA-control, or UDMA-K18 sealant) will be applied clinically and evaluated on extracted teeth in laboratory conditions.

Procedures: Before bonding, one premolar per patient will be assigned to a group. The group each premolar is assigned to will be determined by a randomized, computer generated program. The allocation will be concealed in an opaque envelope that will be opened at the time of initial bonding. If a fourth premolar is planned for extraction, a random selection of the treatments will be selected in a 1:1:1 ratio and this treatment will be applied to the fourth premolar.

At the time of initial bonding, the UDMA and UDMA-K18 sealant will be applied to the selected premolar following manufacturer instructions. Briefly, the clinician will isolate the teeth using the NOLA Dry Field System and excess saliva will be removed by drying the teeth with an air-water syringe. In the treatment group, 37 % Phosphoric Acid will be applied to the entire buccal surface for 30 seconds, rinsed, and dried. Next, the assigned sealant will be evenly applied to the entire buccal surface of the premolar and light cured. The sealant which is adhesive will be applied to the bracket pad and the bracket pad will be pushed to place, excess cement will be removed and light cured.

In the control group, 37 % Phosphoric Acid will be applied for 30 seconds strictly to the area where the bracket will be bonded on the buccal surface, rinsed, and dried. No sealant will be applied. The adhesive sealant will be applied to the bracket pad and the bracket pad will be pushed to place, excess cement will be removed and light cured. After 3-6 weeks, the patient will have their premolars extracted. After extraction they will be placed in a Tooth Storage Solution (25 % ethanol, 75 % water with the addition of saturated hydroxyapatite, 20 mg of NaN3, and 40 mg Thymol) that is antimicrobial and does not alter the tooth surface. These teeth will be collected by the investigators for histologic study.

The collected, extracted teeth will be sectioned using a water-cooled, Buhler slow speed diamond saw in three 2mm sections through the bracket base. A polarized light microscopy (PLM) digitized photograph of the cross-sectional sample will be analyzed to determine the depth of lesions, if present. The mineral density profile will be analyzed using contact micro radiography (TMR).

Inclusion Criteria:

• Orthodontic patients at the Department of Orthodontics Clinic, School of Dental Medicine, University of Colorado who agree to consent to this study.
• Orthodontic treatment plans that include fixed appliances from the second premolar to second premolar in both arches.
• Orthodontic treatment plans that include extractions of at least 3 bicuspids at about 1 month after bracket placement.
• The patient has adequate oral hygiene

Exclusion Criteria:

• Evidence of decalcification or restorations on any of the premolars planned for extraction prior to orthodontic treatment,
• Pregnant women (self reported)
• Any condition that contraindicates orthodontic treatment,
• Not willing to consent to the study.

The COMIRB approval and the consent forms specify that we cannot share PHI except as mandated by law. Therefore we do not intend to share any IPD to other researchers.

10 Months, January 2018 to October 2018

Study participants were provided with a 24-hour hot line to call if they experienced any discomfort associated with the placement of the sealant or orthodontic bracket.

The trial design is triple-blinded. The manufacturer will deliver the blinded treatments in identical bottles labelled A and B, therefore, neither the patient nor the clinician will know which treatment is rendered to each tooth. However, the no sealant control will not be blinded. Blinding will continue to be present during the histological portion of the experiment as the assessors will not be aware of which sealant was used to treat each tooth. After a blinded assessment, blinds will be lifted when between-group analysis is performed.