This clinical trial aimed at studying the durability of an orthodontic sealant (Pro Seal) used on tooth surfaces for protection against white spot lesions. A total of 35 patients (18 females, 17 males; 17.57 ± 1.36 years) were recruited. Eligibility criteria included healthy patients of both sexes (age > 14 years), absence of labial caries, absence of defective enamel, absence of extensive restorations, and optimum oral hygiene. The participants received a single application of Pro Seal on the bonded teeth. The sealant covered the labial enamel surrounding the brackets. Participants were recalled monthly after sealant application, during which sealant layers were evaluated using an ultraviolet lamp. The assessment was realized using an index similar to the adhesive remnant index (ARI). A total of 30 participants completed the trial. ARI values dropped significantly (P < 0.001) and reached <1.5 at T1 on the index used. An ARI value of 2 was chosen as the threshold below which a tooth presented an insufficient sealant layer. The right and left sides of both jaws did not show any statistically significant difference (P > 0.05). ARI values of homolateral teeth revealed few statistically significant differences between upper and lower teeth. No statistically significant difference between the two sexes (P > 0.05) existed. No harm or disturbance was reported by any of the participants. This study demonstrated that a single application of Pro Seal is effective for 4 weeks and should be renewed monthly. No interjaw, intrajaw, or intersex significant differences were found.