The Penetration Depth and Bactericidal Efficacy of 2% Chlorhexidine Iontophoresis in Human Coronal Dentin In Vitro

Abstract

Objectives Iontophoresis could facilitate drug transport into human dentin. This study aimed to investigate the impact of iontophoresis on the penetration depth and bactericidal efficacy of 2% chlorhexidine (CHX) in human coronal dentin using confocal laser scanning microscopy (CLSM). Methods Fifty-one coronal dentin specimens, prepared from 51 extracted intact human third molars, were used in the study, which was divided into 2 series. Series 1 investigated the penetration depth of 2% CHX labeled with rhodamine B dye (CHX + R) in coronal dentin using CLSM, comparing a 5-minute passive treatment and 5-minute iontophoresis (n = 10/group). Series 2: part 2.1 studied the bactericidal efficacy of 2% CHX iontophoresis by determining the percentage of intratubular bacterial viability using CLSM (group 1: noninfected dentin, group 2: untreated infected dentin, group 3: 5-minute distilled water iontophoresis, group 4: 5-minute passive CHX treatment, group 5: 5-minute CHX iontophoresis; n = 5/group); part 2.2 verified the presence of Streptococcus mutans biofilms within dentinal tubules of a dentin infection model by the centrifugation method using scanning electron microscopy (n = 6). The data were analyzed using an independent samples t test (series 1) and a 1-way analysis of variance, followed by the Tukey test (series 2), with a significance level of α = 0.05. Results Five-minute iontophoresis (713.31 ± 169.45 μm) exhibited deeper penetration of CHX + R in coronal dentin than 5-minute passive treatment (199.54 ± 36.83 μm, P < .001). Also, 5-minute CHX iontophoresis could reduce the percentage of intratubular bacterial viability more than 5-minute passive CHX treatment ( P < .001); meanwhile, 5-minute distilled water iontophoresis could not show this effect ( P = .994). Conclusions Anode iontophoresis could increase the penetration depth and bactericidal efficacy of 2% CHX in human coronal dentin. Clinical Relevance A 2% CHX iontophoresis has potential use in reducing the viability of intratubular bacteria in human coronal dentin.