Discussion
inflammation, tooth color enhancement, tooth, tissue damage, orthodontic
INFLAMMATION, EVENTS
The results found on this study showed that bleaching during orthodontic treatment does not appear to be related to an increase in GCF volume. Since GCF collection is a simple and non-invasive procedure, it has been used as a potential indicator of an ongoing inflammation and a useful tool for monitoring post-dental procedures [However, on the other hand, in the FOA group there was a significant increase in the GCF volume, mainly after 28 days of treatment (T1) as expected [Interestingly, despite increasing the GCF volume, the GCF NO- concentration did not change in the FOA group. This means that the increase in GCF volume observed in this study could not be correlated with inflammation after orthodontic movements; however, it was correlated with a stimulus inducing fluid production.In contrast, a significant reduction in the GCF NO- concentrations was detected in the BLE and FOA + BLE groups. In the case of the FOA + BLE group, the bleaching procedure was performed 28 days after the installation of the FOA, because, according to previous studies, inflammatory activity had already been observed [According to the study by Colares et al. [Dental bleaching agents have been suggested to cause tissue damage, a response that is associated with the reduction of GCF NO- levels from 1 to 7 days following dental bleaching [Despite the GCF and NO- concentrations are consider the most adequate method to detect inflammation in patients submitted to in-office bleaching [Unfortunately, several methodological differences between the present and previous studies [Regarding color change, the results of this study showed that the application of hydrogen peroxide at higher concentrations using in-office bleaching demonstrated significant tooth color enhancement during orthodontic treatment when compared with that of the baseline. Although this was in agreement with previous clinical studies [It can be observed that the bleaching agent has the ability to bleach teeth uniformly, even when not in direct contact with the buccal surface. This is because hydrogen peroxide diffusion occurs in multiple directions throughout the tooth structure, allowing for homogeneous bleaching [This can be explained by the permeability of the tooth structure and the lower molecular weight of hydrogen peroxide. Both factors allow that low molecular weight molecules of hydrogen peroxide to easily cross through the enamel surface to dentin by the formation of free radicals that interact with the pigmented organic molecules, destabilizing and bleaching them, and thus producing the whitening effect [It is worth mentioning that both color measurements were superior to 50:50 perceptibility (PT) and 50:50 acceptability threshold (AT). For ΔE, the 50:50 PT value was reported to be 1.2, and the 50:50 AT value was reported to be 2.7 [However, when the BLE group was compared with the FOA + BLE group, some differences were observed when both parameters were compared (ΔETherefore, it is important to compare both the groups using ΔWIConsidering that this was the first randomized clinical study that showed that the use of orthodontic appliances disturbs the bleaching process to some degree, it seems to be an important conclusion. However, the bleaching efficacy can be potentially improved with one additional session of in-office bleaching [Finally, it is worth mentioning that despite the present study have evaluated all hypothesis in posterior teeth, which is not consider teeth in an aesthetic area, it will be expected the same events, in terms of bleaching effect or due to underwent fixed orthodontic appliance in the anterior teeth. Also, as in-office bleaching using high-concentrated hydrogen peroxide in forbidden in several parts of the World, mainly in the European community, this negatively impact the external validity of the present study.Actually, dental bleaching can act as a motivating factor, avoiding patient withdrawal or interruption of treatment. However, as in the present study, the use of orthodontic appliance was the most important factor influencing the inflammatory activity in periodontal tissue. It demonstrated that participants undergoing orthodontic treatment who choose dental bleaching need to have good periodontal health to perform this procedure. If we are taking in account the increase of use of aligners instead fixed appliance, and the use of the same aligners as bleaching tray, this could be other interesting suggestion to associate orthodontic aligners with at-home bleaching [