## 4 Discussion  
In the present study, it was observed that desensitizing agents are able to significantly decrease DH in adults after a short follow-up of 30 days. Moreover, it has been reported  
Figure 8: Mean values of omni-comprehensive DH stimuli responses score trend from T0 to T2 in the whole sample. Figure 7: Mean values of acid sensitivity test trend from T0 to T2 in the whole sample. that these agents were effective in reducing DH against different stimuli including tactile, cold thermal, osmotic, and acid agents. In previous studies, it was reported that patients tend to overestimate DH self-perception, and it may be possible that routinary clinical tests limited to tactile or air test did not completely evaluate the full aspects of DH due to the influence psychological status and self-perception seem to have on this pathology [9; 12]. For this reason, we have introduced an omni-comprehensive index that was able to evaluate all aspects linked to DH. As previously discussed, there are several theories on the etiology of dentin hypersensitivity, such as hydrodynamic theory, modulation theory, transducer theory, and gate control theory; but none of these, however, have been fully proved. Therefore, we can conclude that all etiological factors and trigger agents linked to DH are not fully understood, and a full analysis of different agents may be helpful in the evaluation of this condition. We have observed that the air test did not show significant differences after the follow-up. This could have been caused by the methodology applied in the present study, since for this index a scale from 0 to 3 was adopted while a VAS scale with a higher range from 0 to 10 was used for other tests. Furthermore, the subjective aspect of the tests that rely on patients' perception should be considered. In the present study, a slight increase at T1 was recorded for most of the tests, which can be justified by a temporary hypersensitivity following the professional oral hygiene session; moreover, a likely greater awareness of DH by the patient, following the clinical instruction of the dental professional, may have increased DH self-perception. This slight increase of DH, however, has been reported as only temporary since DH decreased significantly at T2, seemingly because of the use of desensitizing devices. Therefore, we may assume that these desensitizing agents need at least 30 days in order to achieve a significant DH decrease. Regarding the differences between the two toothpastes, we can state that both were effective in reducing DH against all stimuli from T0 to T2; a slight difference in favor of product B (a toothpaste containing n-HAp in effective dose 2.25% and 0.15% fluoride, 1500 ppm) was observed, but no statistical significance was observed for this comparison. The patients' age seemed to affect both the SCASS scale and the final omni-comprehensive score, since significantly lower scores have been registered in older patients, with an inversely proportional ratio. This could be caused by the natural accumulation of secondary and tertiary dentin with a partial obliteration of dental tubules during aging. Furthermore, diet plays an important role on the onset and development of dentinal hypersensitivity because of the acidic properties of foods; younger people consume high quantities of soft and sugary drinks, which are one of the main causes of hypersensitivity along with nocturnal or diurnal bruxism, wrong brushing techniques, use of toothpushes with hard bristles, and presence of periodontal diseases with gingival recessions [3]. At the time of onset, since this condition can occur very early in young adults, it is necessary to stop any bad habits and use specific agents that favor remineralization such as: toothpastes, mouthwashes, tooth mouse, and topical application of varnishes. The Dental School of the University of Turin, in 2016, published a study titled \"Comparative clinical evaluation of the efficacy of two professional products for the management of dentinal hypersensitivity: a split-mouth study\" [40].