# Low-Level Laser Therapy for Tooth Sensitivity after Tooth Bleaching: A Systematic Review
## 4 Discussion
Of special interest are several studies that, although they did not meet our inclusion criteria, present compelling findings. One such case is a case report study [37] conducted concurrently with that of [PERSON] et al. [27] and involving only six participants. The researchers employed a split-mouth design to compare LLLT with a control group after administering two different in-office bleaching agents (35% HP and 6% HP N-doped TiO\({}_{2}\) nanoparticles). Similar to the majority of the RCTs included, this study demonstrated that LLLT effectively reduced pain intensity after mechanical and evaporative stimuli for up to 48 h post-TB, with analgesia persisting after 72 h. Furthermore, a randomized clinical trial by [PERSON] et al. [38] suggested that teeth subjected to LLLT prior to the bleaching session, followed by the topical application of 5000 ppm sodium fluoride, exhibited less TS than those treated solely with sodium fluoride (\(p\leq 0.05\)) across various evaluation times. Additionally, [PERSON] et al. [39], in their split-mouth clinical study, proposed that LLLT, when administered before TB, prevented TS more effectively than a placebo, as indicated by daily pain assessment questionnaires (\(p\leq 0.05\)), despite showing no significant difference in evaporative stimulus pain evaluation (\(p>0.05\)). These studies, despite employing LLLT before bleaching, contribute to the growing body of evidence supporting the efficacy of LLLT for controlling post-bleaching TS. The primary strength of the present systematic review lies in its rigorous adherence to strict inclusion criteria. Amidst the diverse array of protocols and parameters explored in the literature, this review exclusively incorporates RCTs with a minimum of ten participants in each group and only compares LLLT to non-LLLT interventions following in-office bleaching sessions. This approach aims to enhance the homogeneity and comparability of the studies, thereby bolstering the robustness of the outcomes. Unlike previous reviews, which lacked such stringent criteria, this systematic review includes only studies that meet these specific requirements, making it the first and most comprehensive systematic review encompassing solely RCTs assessing the efficacy of LLLT on tooth sensitivity. The two previous systematic reviews [40; 41] encompassed non-RCTs studies where LLLT could be used either before or after tooth bleaching [29; 42]. In addition, the current systematic review covers more studies--six in total--including the two most recently published [5; 31], which were overlooked in the previous systematic reviews. The review, however, is marked by certain limitations that necessitate consideration when interpreting its findings. Significant heterogeneity exists among the studies analyzed concerning the type and concentration of bleaching agents, the number and duration of the sessions, and the utilization of light/heat to expedite the process. Similarly, variations in laser parameters--such as type, wavelength, power, energy, pulse duration, total duration, distance from the surface, beam diameter, and point of irradiation--add another layer of complexity to the analysis. Furthermore, the definition of tooth sensitivity varies across studies, which restricts the generalizability of the results obtained. Pain perception is inherently subjective and subject to individual differences influenced by various factors. Moreover, individual variations in tooth anatomy, including enamel and dentin thickness, as well as pulp vitality, can significantly influence sensitivity sensations [19]. From the preceding discussion, it appears that LLLT could offer practical advantages for clinical application and patient care. Initially, its effectiveness has been shown to be comparable to that of other desensitizing therapies for managing post-bleaching tooth sensitivity. Unlike certain desensitizing treatments that require strict adherence to specific application protocols, such as NaF varnish, LLLT demands minimal compliance from patients.