Comparison of neurotoxicity of root canal sealers on spontaneous bioelectrical activity in identified Helix neurones using an intracellular recording technique.
OBJECTIVE
To evaluate the neurotoxic effects of two endodontic sealers, AH-26 and Roth 801, on firing excitability and action potential configuration of F1 neural cells in the suboesophageal ganglia of Helix aspersa.


METHODS
A conventional intracellular current clamp technique was used to study the blocking effects of AH-26 and Roth 801 on ionic currents underlying the action potential of F1 nerve cells. The sealers were prepared according to the manufacturers' directions and were applied to the bathing media in two ways: invasive (0.05 mL of total mixture of each sealer was applied at a distance of 3 mm from the cell), or gradual (0.05 mL of the extract of each dissolved mixture of sealers in normal Ringers solution was perfused).


RESULTS
When applied in an invasive mode, both sealers reduced the duration, the amplitude of action potentials and the amplitude of after-hyperpolarization potentials significantly and led to dramatic changes in action potential configuration. In the gradual mode of application, AH-26 showed a biphasic action; it first increased the excitability and then decreased the action potential parameters, while Roth 801 exhibited solely blocking effects.


CONCLUSIONS
Both sealers had significant inhibitory effects on excitability of F1 neuronal cells.
Asgari
S
S
Department of Endodontics, Faculty of Dentistry, Shaheed Beheshti Medical Sciences University, Tehran, Iran.
Janahmadi
M
M
Khalilkhani
H
H
D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D001729:Bismuth / Q000633:toxicity; D004338:Drug Combinations; D004853:Epoxy Resins / Q000633:toxicity; D017952:Ganglia, Invertebrate / Q000187:drug effects; D006372:Helix, Snails; D007473:Ion Channels / Q000187:drug effects; D009474:Neurons / Q000187:drug effects*; D012387:Root Canal Filling Materials / Q000633:toxicity*; D012815:Signal Processing, Computer-Assisted; D012834:Silver / Q000633:toxicity; D014025:Titanium / Q000633:toxicity; D015035:Zinc Oxide-Eugenol Cement / Q000633:toxicity
D004338:Drug Combinations; D004853:Epoxy Resins; D007473:Ion Channels; D012387:Root Canal Filling Materials; D015035:Zinc Oxide-Eugenol Cement; D012834:Silver; C028044:epoxy resin AH-26; C074935:Roth's 801 Sealer; D014025:Titanium; D001729:Bismuth