Effect of root canal preparation techniques on chlorhexidine substantivity on human dentin: a chemical analysis

Abstract

Chlorhexidine binds to dentine to provide sustained action. The aim of the present study was to evaluate and compare the substantivity of chlorhexidine using manual, rotary, and reciprocating systems for root canal preparation. Forty-five extracted human single-rooted teeth were used for this study. The samples were divided into three groups (n=15) according to the instrumentation technique used: manual instrumentation (K-File), rotary instrumentation (ProTaper), and reciprocating instrumentation (Reciproc R25). Chlorhexidine gel (2%) was used as auxiliary chemical substance during root canal preparation. Longitudinal grooves were carved on the free surfaces of the roots, providing two halves of each root and resulting in 30 samples per group. Each group was randomly divided into three subgroups (n=10), and substantivity was evaluated after 48h, 7days, and 30days of incubation. The amount of CHX (in mg/mL) was measured through reverse-phase high-performance liquid chromatography. Statistical analysis was performed by analysis of variance and the Tukey test for post hoc comparisons (α=0.05). The manual did not show a statistical significant difference with rotary instrumentation (P>0.05), but higher CHX substantivity was recorded in all periods of observation when compared to reciprocating instrumentation (P<0.05). The CHX substantivity on human dentine is lowest when using reciprocating compared to manual and rotary instrumentation. Using chemical analysis, this study showed that a manual and rotary multi-instrument system results in greater chlorhexidine substantivity on human dentin than a reciprocating single-instrument system.