Vittorio Franco

Final Rinse Optimization: Influence of Different Agitation Protocols

INTRODUCTION This study examined the effect of different root canal irrigant agitation protocols in the penetration of an endodontic irrigant into dentinal tubules. METHODS Fifty-six human single-rooted teeth were shaped with nickel-titanium instruments, and a final rinse of 5% sodium hypochlorite labeled with 0.2% alizarin red was performed. Specimens were assigned to 7 groups (N = 8) and submitted to the following rinse activation protocols: no agitation (control group), K-File or gutta-percha agitation, or different sonic (EndoActivator [Advanced Endodontics, Santa Barbara, CA] and Plastic Endo, Lincolnshire, IL) and ultrasonic (Satelec [Acteongroup, Merignac, France] and EMS, Nyon, Switzerland) agitations. Specimens were sectioned at 1, 3, and 5 mm from the apex in 1-mm-thick slabs, ground, and prepared for fluorescence microscopy at 100x with a wavelength of 450 milliseconds. Irrigant penetration into dentinal tubules was analyzed by using Kruskal-Wallis analysis of variance followed by post-hoc comparisons. RESULTS Groups were ranked in the following order: control = K-file = gutta-percha < EndoActivator = Plastic Endo < Satelec = EMS. At 1 mm from the apex, the highest score was found for the EMS group compared with the control, K-file, gutta-percha, EndoActivator, and Plastic Endo groups, whereas no difference was found with the Satelec group. CONCLUSION The results support the use of an ultrasonic agitation to increase the effectiveness of the final rinse procedure in the apical third of the canal walls.

Removal of Surgical Smear Layer

INTRODUCTION During apicoectomy and retrograde cavity preparation, a smear layer, which contains microorganisms and necrotic pulpal tissues, is formed on the dentinal surfaces cut by the instruments. Bacteria can survive and proliferate inside or below the smear layer. The purpose of this study was to evaluate in vitro two different procedures for the removal of the smear layer in retrocavities prepared with ultrasonic retrotips. METHODS Twenty-eight single-rooted teeth were cleaned, shaped, and obturated with gutta-percha and sealer. The apical 3 mm of each root were cut with a carbide bur, and retrograde cavities were prepared with ProUltra ultrasonic retrotips (Maillefer Dentsply, Baillagues, Switzerland) at a depth of 3 mm. Teeth in group A were treated with a gel of 35% orthophosphoric acid for 15 seconds, and teeth in group B were treated with a gel of 24% EDTA at a neutral pH for 2 minutes. The samples were prepared for scanning electron microscopic observation and scored for the presence of the smear layer on the retrocavity walls. RESULTS Eighty percent of the teeth in group A showed an optimal degree of cleanliness of the walls, with dentinal tubules completely open. The majority of analyzed samples coming from group B showed dentinal tubules covered with the smear layer. CONCLUSIONS The analysis of the samples showed that orthophosphoric acid is more effective than EDTA in removing surgical smear layer even with less time of action.

Computed microtomography study of untreated, shaped and filled mesiobuccal canals of maxillary first molars

This study assessed the effectiveness of modern endodontic shaping and filling procedures on mesiobuccal roots of maxillary molars with two canals. The canals of 20 mesiobuccal roots were treated with Mtwo rotary files, passive ultrasonic irrigation and Guttafusion obturators. X-ray computed microtomography analysis was carried out prior to treatment, after canal shaping and after canal filling to determine the alterations of the canal volume before and after the instrumentation, the volume of the hard tissue debris, and percentage of the volume occupied by filling materials. The shaping instruments and filling materials reached only partially the endodontic space of the second mesiobuccal canal and the accessory endodontic structures. Canal irregularities, ramifications, and interconnections were accumulation sites of hard tissue debris. This study demonstrated that rotary files, passive ultrasonic irrigation and carrier-based filling systems could be partially effective for the treatment of the mesiobuccal canals and their accessory endodontic structures.