The effect of 2% chlorhexidine iontophoresis on dentin sealing ability of etch-and-rinse adhesive: An in vitro study

Abstract

Background/purpose: Iontophoresis could enhance the delivery of chlorhexidine into oral tissue. This study aimed to determine the effect of 2% chlorhexidine iontophoresis (CHI) on the sealing ability of etch-and-rinse adhesive in human dentin using hydraulic conductance (HD) measurement, scanning electron microscopy and energy dispersive x-ray spectroscopy (SEM-EDS).

Materials and methods: Thirty-nine sound dentin specimens were prepared from 39 extracted intact third molars. Thirty specimens were used for HD measurement and randomly divided into 3 equal-sized groups; (1) No chlorhexidine treatment (control), (2) passive chlorhexidine treatment (CHT) and (3) CHI on acid-etched dentin. Each dentin surface was treated with etch-and-rinse adhesive. HD of each specimen was measured before treatment, after immediate bonding and after 14 days. The other 9 specimens were subjected to SEM-EDS analysis of the acid-etched dentin and the dentin treated with CHT and CHI. ANOVA test and Student-Newman-Keuls method were used for statistical analysis.

Results: After bonding, there was no significant difference in percentage decrease of HD among the treatment groups (P > 0.05). After 14 days, CHI and CHT groups had greater percentage decrease of HD than the control (P < 0.001 and P = 0.009, respectively). Under SEM-EDS analysis, acid-etched dentin with CHI presented opened dentinal tubule orifices and more chlorhexidine precipitates on dentin than the dentin with CHT, which strongly related to a higher percentage of chloride ions on the CHI dentin surface (P < 0.001).

Conclusion: The use of CHI on acid-etched dentin had a positive effect on dentin sealing ability of etch-and-rinse adhesive.

Keywords: Chlorhexidine; Etch-and-rinse adhesive; Human dentin; Iontophoresis; Sealing ability.

Figure 1

Diagram of the experimental set up for chlorhexidine iontophoresis.

Figure 2

Mean (±1 SD) percentage decreases of hydraulic conductance of human dentin after bonding immediately (black column) and after 14 days (gray column) in no chlorhexidine treatment, passive chlorhexidine treatment and chlorhexidine iontophoresis groups. The same lowercase letter represents no significant difference between after bonding and after 14 days. The same uppercase letter represents no significant difference among the treatment groups (P > 0.05, 2-way RM ANOVA and Student-Newman-Keuls method).

Figure 3

(A–C) Scanning electron micrographs of etched dentin surface (original magnification X3000, scale bar = 5 μm): (A) no chlorhexidine treatment (control); (B) passive chlorhexidine treatment; (C) chlorhexidine iontophoresis. Arrow heads showing chlorhexidine precipitates on treated dentin surfaces.

Figure 4

Energy-dispersive X-ray spectroscopy (EDS) spectra taken from the treated dentin surface of (A) No chorhexidine treatment, (B) passive chlorhexidine treatment, (C) chlorhexidine iontophoresis with the right table for the weight and atomic percentage of the following elements: C–carbon, N–nitrogen, O–oxygen, P–phosphorus, Cl–chloride, Ca–calcium.