Short-Term Gingival Microcirculatory Responses to Non-Invasive Physical Stimulation: Implications for Accelerated Orthodontic Research

Background/Objectives: Acceleration of orthodontic tooth movement remains a major challenge in clinical orthodontics. Evidence suggests that increased local blood flow around the alveolar bone is key to bone remodeling and potentially reflects early biological responses associated with accelerated orthodontics. This study aimed to investigate the effects of non-invasive physical stimuli on gingival microcirculation. Methods: Eight healthy adult male volunteers were included in the analysis. Gingival blood flow was assessed using laser Doppler flowmetry under the following conditions: no-stimulation condition (None) and four types of stimuli: thermal stimulation (THM), electric field stimulation (ELF), vibration stimulation (VIB), and far-infrared stimulation (FIR). Gingival blood flow was recorded before and after each stimulation, and the rate of change was calculated. Statistical analysis was performed using a linear mixed-effects model with Type III ANOVA (Satterthwaite approximation), followed by Dunnett-adjusted comparisons. Results: A statistically significant difference was observed between stimulation conditions (p = 0.0087). VIB significantly increased gingival blood flow compared with the no-stimulation condition (p = 0.0041), whereas ELF showed a trend toward increased blood flow (p = 0.0936); THM and FIR showed no statistically significant effects. Conclusions: The findings of this study suggest that non-invasive physical stimuli, particularly vibration stimulation, can enhance gingival microcirculation. Although tooth movement was not directly evaluated, the observed hemodynamic changes may represent short-term physiological responses to non-invasive physical stimulation.