Efficacy of Bioelectric Toothbrush in Reducing Gingival Inflammation: A Randomized Controlled Trial

Technical Summary: Efficacy of Bioelectric Toothbrush in Reducing Gingival Inflammation

Problem Statement
Mechanical plaque control is the primary strategy for preventing plaque-induced gingivitis, yet conventional methods often fail to fully disrupt the protective extracellular polymeric substance (EPS) matrix of mature bacterial biofilms. While powered toothbrushes (sonic and oscillating-rotating) generally outperform manual brushes, their efficacy can be limited by technique sensitivity and the inability of bristles to physically access anatomically constrained regions like interproximal spaces and the subgingival sulcus. Bioelectric (BE) technology, which utilizes low-level microcurrents (50–200 µA) to electrochemically weaken the EPS matrix and disrupt bacterial quorum sensing, has emerged as a potential adjunct. However, randomized controlled trials (RCTs) directly comparing BE toothbrushes against established sonic technologies in a clinical setting are limited. This study addresses the need to evaluate the clinical efficacy of a BE toothbrush compared to standard manual and sonic toothbrushes in reducing gingival inflammation and plaque.

Methodology
This was a single-center, examiner-blinded, parallel-group, randomized controlled trial conducted at Ulsan University Hospital, Republic of Korea.

• Participants: 99 systemically healthy adults (aged 18–65) with mild-to-moderate plaque-induced gingivitis were enrolled. Inclusion required at least 20 functional natural teeth, probing depths ≤ 3 mm, and bleeding on probing (BOP) in 10–50% of sites. Exclusion criteria included smoking, pregnancy, severe periodontitis, and recent use of antibiotics or anti-inflammatory drugs.
• Interventions: Participants were randomly assigned (1:1:1) to one of three groups (n=33 per group):
  1. Manual: Standard flat-trim manual toothbrush (Oral-B® Indicator®).
  2. Bioelectric (BE): A toothbrush emitting a microcurrent of 50–200 µA at 10 MHz via a superimposed AC/DC waveform (Great Gums®; ProxiHealthcare Inc.).
  3. Sonic: A low-to-mid-range powered sonic toothbrush (Aquasonic® Icon™).
• Protocol: All participants brushed twice daily for 2 minutes using a standardized fluoride dentifrice. The study duration was 4 weeks.
• Outcomes: Primary outcome was the baseline-adjusted mean Gingival Index (GI) at week 4. Secondary outcomes included Plaque Index (PI) and percentage of Bleeding on Probing (%BOP).
• Statistical Analysis: Due to a baseline imbalance in PI scores, the primary efficacy analysis utilized Analysis of Covariance (ANCOVA) with baseline values as covariates. Pairwise comparisons were adjusted using the Bonferroni correction.

Key Results

• Gingival Inflammation (GI): At week 4, the BE group achieved a significantly lower baseline-adjusted mean GI score (0.822) compared to both the manual group (1.414; P < 0.001) and the sonic group (1.078; P = 0.023). The BE group demonstrated a 91.82% reduction in GI from baseline, significantly outperforming the sonic (54.55%) and manual (18.71%) groups.
• Plaque Control (PI): Both the BE and sonic groups showed significantly lower adjusted mean PI scores than the manual group (P = 0.002). There was no statistically significant difference between the BE and sonic groups.
• Bleeding on Probing (%BOP): The BE group achieved a significantly lower adjusted mean %BOP (8.76%) compared to the manual group (14.30%; P = 0.033). The difference between the BE and sonic groups (13.11%) was not statistically significant (P = 0.124).
• Safety: No adverse events, oral soft tissue abnormalities, or damage to dental restorations were reported in any group.

Significance and Claims
The paper claims that the bioelectric toothbrush demonstrated superior efficacy in reducing clinical signs of gingival inflammation compared to both manual and sonic toothbrushes over a 4-week period. Notably, the BE group's mean %BOP of 8.76% fell below the 10% threshold defined by the 2017 World Workshop as indicative of clinical gingival health on an intact periodontium.

The authors posit that the BE group's ability to achieve lower inflammation scores despite plaque scores comparable to the sonic group suggests a mechanism beyond simple mechanical removal. They hypothesize that the microcurrent may disrupt the biofilm's EPS matrix, thereby reducing the inflammatory potential of residual biofilm. However, the paper explicitly states that these biological mechanisms were not directly evaluated and remain speculative; the findings demonstrate clinical efficacy rather than confirming the underlying mechanism of action.

The study concludes that bioelectric technology is a promising non-chemical adjunct for daily plaque control, offering short-term clinical utility. The authors maintain a modest tone regarding long-term implications, noting that the 4-week duration precludes conclusions about long-term periodontal maintenance or systemic health benefits, and that future studies with longer follow-ups and microbiological assessments are required to fully elucidate the technology's potential.