Effect of Passive Ultrasonic Activation on Organic Tissue Dissolution from Simulated Grooves in Root Canals Using Sodium Hypochlorite with or without Surfactants and EDTA.

INTRODUCTION: The aim of this study was to evaluate the porcine palatal mucosa dissolution from artificial grooves using a final rinse with sodium hypochlorite (NaOCl) with or without a surfactant or ultrasonic activation (PUI).

METHODS: The root canals of 130 human maxillary central incisors were chemomechanically prepared and the teeth split. A standardized longitudinal intracanal groove was created in 1 of the root halves. One hundred thirty porcine palatal mucosa samples were collected, adapted in order to fit into the grooves, and weighed. The reassembled specimens were randomly divided in 3 experimental groups (n = 40) based on their irrigation protocol (ie, positive pressure [PP] and PUI during 15 [PUI-15] or 30 seconds [PUI-30]) and divided in subgroups according to the NaOCl preparation used: Vista 6% plain (Vista Dental Products, Racine, WI) or Chlor-XTRA (Vista Dental Products) (containing surfactant). An EDTA intermediate rinse was included. Palatal mucosa weights were measured after the assays. The intergroup weight changes were statistically analyzed.

RESULTS: Complete dissolution did not occur in any sample. Chlor-XTRA subgroups were associated with increased weight reduction compared with Vista 6% plain subgroups; however, the differences were significant (P < .05) only for PP and PUI-15. PUI-30 increased weight reduction compared with PP for both hypochlorites and PUI-15 using Vista 6% plain (P < .05). PUI-30 with Vista 6% plain performed significantly better than PP with Chlor-XTRA (P < .05).

CONCLUSIONS: The addition of a surfactant to NaOCl and/or PUI activation increased palatal mucosa dissolution within artificial grooves in the root canal of incisor teeth. PUI agitation was often able to compensate for the absence of surfactants.