## 4 Discussion
On the other hand, the best results in pain reduction after EAT stimulation recorded using the VAS score, both after 1 week and after 1 and 6 months, were found for patients in Group 2, with total VAS scores of 41, 51, and 65 and means of 1.20, 1.5, and 1.91, respectively. This indicates that VivaSens is quickly effective when used alone and even more performing when associated with diode laser irradiation compared to NaF, used alone or associated with DL. Several studies have shown the efficacy of VivaSens as an in-office desensitizing agent. Our findings are consistent with the findings of [PERSON] et al. who evaluated the ability of the desensitizing agents VivaSens and DL on dental tubule occlusion and their effectiveness over time using scanning electron microscopy on extracted teeth. The search concluded there was no statistically significant difference between the VivaSens and the Laser groups. This indicates that both agents are equally effective in the obliteration of dental tubules [24]. Our study shows that NaF associated with DL represents the treatment of choice in the short and long term (t2, t3, and t4, with total VAS scores of 41, 51, and 65, respectively). These data are in agreement with a previous study performed by [PERSON] et al. that showed that the use of NaF associated with DL diode laser had a very high capability to provide relief of DH-related pain, both immediately and after 1 and 6 months from the treatment, compared to NaF and DL used alone and to the Gluma Desensitizer [18]. The effectiveness of NaF is related to mechanical occlusion linked to the precipitation of insoluble calcium fluoride (CaF) crystals within the tubules, without adhesion. The lower short- and long-term efficacy of NaF in comparison with NaF plus DL may be attributed to a fairly rapid loss of the occluding layer of CaF due to dissolution in saliva [25]. VivaSens is a desensitizer agent in an alcohol-based liquid solution, containing polyacrylic acid modified with methacrylate and potassium fluoride without glutaraldehyde, which creates a film-like varnish on the tooth surface and relieves pain through various mechanisms. VivaSens seals the dental tubules by inducing the precipitation of proteins and calcium in the dental fluid (mechanical work), while the presence of potassium fluoride provides additional protection with a rapid pain reduction resulting from the depolarization of nerve fibers (neural mechanism). This explains the rapidity of action of this agent on pain relief, which improves with the association with a DL (total VAS score and mean in SG3 of 30 and 0.97 and in SG4 of 26 and 0.90, respectively) immediately at the end of the treatment. The association of DL with VivaSens does not enhance the effect for a long time probably because, over time, the effectiveness of potassium fluoride is reduced, leaving only the precipitation of proteins in the dental fluid to guarantee a mechanical blockage of the open dental tubules. These results are in agreement with previous in vivo studies evaluating the efficacy of VivaSens on DH pain and detecting a rapid pain relief, though with no statistical difference in comparison with other tested desensitizing agents [26,27]. The data in our study showed a higher long-term effectiveness of NaF in association with DL used at a low power (0.5 Watt) on the reduction of pain caused by DH, in comparison with NaF used alone, probably because at the power chosen, DL had bio-stimulating effects on dentin, promoting the formation of new dentin, which could justify the longer duration of the protective effect on pain. In addition, the higher effectiveness of the use of NaF when associated with the DL compared to VivaSens may be related to the action of the diode laser that could allow a deeper penetration of NaF into the dentin tubules, facilitating the precipitation of CaF, which, in combination with laser-induced occlusion derived from the superficial melting of proteins into the dentin fluid, maintains the occlusion of tubules longer, lessening the discomfort from DH [28].