Subgingival Plaque Removal Efficacy and Oral Soft Tissue Safety of the Wave Electric Toothbrush: An In Vitro and In Vivo Study

<b>Background/Objectives</b>: The novel wave electric toothbrush is considered potentially helpful in removing subgingival plaque to prevent the occurrence of periodontal diseases. This study aimed to assess the cleaning efficacy of a novel wave electric toothbrush on subgingival plaque and its safety profile for oral soft tissues. <b>Methods</b>: In vitro cleaning efficacy evaluations were conducted using oral dental models. The wave electric toothbrushes were divided into low-, medium-, and high-swing parameter groups, with manual brushing (Bass technique) as the control. Simulated plaque was applied to the buccal and gingival sulcus sites of the four first molars, and the plaque removal area and sulcus cleaning depth were measured. For safety evaluation, Sprague Dawley (SD) rats were brushed on their molars daily for 30 days, with bleeding incidents recorded. Oral soft tissues were analyzed through H&E staining and immunohistochemical analysis. Statistical analysis included ANOVA and Kruskal-Wallis (<i>p</i> < 0.05). <b>Results</b>: Medium- and high-swing groups demonstrated superior gingival sulcus cleaning efficacy, showing significant differences compared with the low-swing and control groups (<i>p</i> < 0.05). All swing parameters achieved complete plaque removal on buccal surfaces. No significant differences were observed between the low-swing and manual groups, or between the medium- and high-swing groups, regarding sulcus cleaning efficacy and maximum sulcus depth. During the 30-day in vivo experiment, medium- and high-swing groups showed low bleeding frequencies, primarily at the palatal gingiva and vestibule. Histological analyses indicated that higher swing parameters increased the likelihood of soft tissue injury. <b>Conclusions</b>: Wave electric toothbrushes enhance subgingival plaque removal, with higher swing parameters improving gingival sulcus cleaning. However, stronger parameters may increase the risk of soft tissue damage. Further clinical studies are required to establish optimal guidelines.