Evaluation of chlorhexidine substantivity on human dentin: a chemical analysis.
BACKGROUND
The aim of this study was to investigate the substantivity of chlorhexidine (CHX) solution and gel within a root canal system for 24 hours, 30 days, and 90 days.


METHODS
Forty-five extracted human anterior teeth were used for this study. The samples were divided into 3 groups according to the chemical auxiliary substance used to perform the root canal preparation: group 1, 2% liquid CHX; group 2, 2% gel CHX; and group 3, distilled water (the control group). The working length was determined by inserting a #10 K-file into the canal up to the moment its tip was seen in the apex foramen and then withdrawing it 1 mm. The roots were prepared up to the instrument #45. Longitudinal grooves were carved on the free surfaces of the roots, providing 2 halves of each root and resulting in 30 samples per group. Each group was randomly divided into 3 subgroups (n = 10), and substantivity was evaluated after 24 hours, 30 days, and 90 days of incubation. The amount of CHX (in micrometers) 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).


RESULTS
The control group showed no substantivity. Significant amounts of CHX solution and gel remained retained in dentin substrates independent of the time of incubation (P < .05). CHX solution showed a higher substantivity than CHX gel, with the exception of groups incubated for 90 days. The decreasing amounts of retained CHX inside the canal were for 24 hours >30 days >90 days for CHX solution and 24 hours >30 days ≥ 90 days for CHX gel.


CONCLUSIONS
The results of this study indicate that CHX solution and gel are retained in root canal dentin for up to 90 days.
Department of Restorative Dentistry, UPF, Passo Fundo, Rio Grande do Sul, Brazil.
Matheus
M
Souza
Doglas
D
Cecchin
Ana Paula
AP
Farina
Carlos Eduardo
CE
Leite
Fernanda Fernandes
FF
Cruz
Charles da Cunha
Cda C
Pereira
Caio Cezar Randi
CC
Ferraz
José Antônio Poli
JA
Figueiredo
D000328:Adult; D000891:Anti-Infective Agents, Local / Q000008:administration & dosage / Q000032:analysis / Q000494:pharmacology*; D002710:Chlorhexidine / Q000008:administration & dosage / Q000032:analysis / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D056148:Chromatography, Reverse-Phase; D003786:Dental Pulp Cavity / Q000187:drug effects*; D003804:Dentin / Q000187:drug effects*; D005782:Gels; D006801:Humans; D008422:Materials Testing; D012388:Root Canal Irrigants / Q000008:administration & dosage / Q000032:analysis / Q000494:pharmacology*; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods; D012996:Solutions; D013997:Time Factors; D055815:Young Adult
D000891:Anti-Infective Agents, Local; D005782:Gels; D012388:Root Canal Irrigants; D012996:Solutions; D002710:Chlorhexidine