Date of Graduation


Document Type


Degree Type



School of Dentistry



Committee Chair

Peter Ngan

Committee Co-Chair

Erdogen Gunel

Committee Member

Elizabeth Kao

Committee Member

Chris Martin


Introduction: Enamel demineralization adjacent to orthodontic brackets is one of the risks associated with orthodontic treatment. Among the techniques utilized to prevent demineralization, application of orthodontic sealants is widely used to provide mechanical coating and fluoride release for the underlying enamel. The purpose of this study was to compare the efficacy in enamel protection during fixed orthodontic treatment in-vitro and in-vivo between two orthodontic sealant products; Opal Seal (Opal Orthodontics by Ultradent, South Jordan, UT) and Pro Seal (Reliance Orthodontic Products, Itasca, IL). The null hypothesis was that there would be no significant difference in protection against enamel demineralization between Pro Seal and Opal Seal.;Materials and Methods: in-vitro: A total of 27 extracted human third molars with no enamel lesion were collected and cut in half to provide 54 samples. These samples were sterilized and randomly divided into three groups: Control, Opal Seal, and Pro Seal groups. The control group received no treatment. The samples in the sealant groups were etched with 37% phosphoric acid and treated with the assigned sealant according to the manufacturers instruction. The samples then underwent 0, 2, or 4 hours of brushing treatments, followed by 24 or 48 hours of demineralization and remineralization treatment. The depth and area of the lesion and thickness of remaining sealant were examined using confocal microscopy. in-vivo: A total of 19 patients who required comprehensive orthodontic treatment were recruited for the study. Tooth surfaces from second premolars to second premolars were treated with either Opal Seal or Pro Seal using a split-mouth technique. The extent of enamel lesions before and after 14 months of orthodontic treatment was examined with digital photography, using a Visual Scoring System. Data were analyzed using ANOVA and Tukey Kramer test for the in-vitro experiment and logistic regression for the in-vivo experiment. Results: in-vitro: Significant difference in lesion depth was found between the control group (40.11+/-16.77 microm) and sealant groups (Opal: 21.44+/-12.46 microm, Pro: 22.01+/-13.58 microm) (p<0.0001). Significant difference in lesion area was found between the control group (35169.17+/-10816.08 microm2) and sealant groups (Opal: 15566.62+/-9339.36 microm2, Pro: 16685.12+/-10375.36 microm2) (p<0.0001). No differences were found between two sealant groups. The remaining sealant thickness showed a linear decreasing pattern over brushing time. However, no significant differences were found in the remaining thickness between the two sealants. in-vivo: Significant correlation was found between the oral hygiene status and the probability of demineralization (p<0.0001). The incidence of white spot lesions increased exponentially with the decline in oral hygiene level. Conclusion: The application of sealant reduced the depth and area of enamel lesions in-vitro. Pro Seal and Opal Seal provided comparable level of enamel protection in-vivo. The duration of sealant protection as demonstrated with an average of 11.3 hours of mechanical brushing was equivalent to 5.65 months of brushing twice a day clinically. It is recommended to reapply sealants every six month in order to provide the full benefit of sealant treatment especially among the patients with poor oral hygiene.