ABSTRACT Objective: To compare the influence of different clinical operative motions (pecking motion vs. MIMERACI) on apical debris extrusion using WaveOne Gold and EdgeOne Fire reciprocating files in the mesiobuccal canal of extracted molars. Material and Methods: Sixty mandibular molar teeth with curvature less than 20° were divided into 4 groups (n=15 each): G1A: WOG pecking Group; G1B: WOG MIMERACI Group; G2A: EOF pecking Group; and G2B: EOF MIMERACI Group. The produced debris was collected in the preweighed Eppendorf tubes and following the shaping procedures; they dried in the incubator for 5 days at 70º C. The tubes were weighed again, and the final extruded debris was measured by subtracting the pre-instrumentation from post-instrumentation weight of tubes. The canal preparation time was calculated with a digital chronometer. The obtained data were analyzed using two-way ANOVA at a 0.05 level of significance. Results: MIMERACI method significantly decreased the amount of debris pushed out in both instruments (p<0.05). Neither instruments nor clinical motions created a statistical difference regarding the required time (p>0.05). Conclusion: All tested instruments pushed debris out apically at some level, but MIMERACI operative technique was associated with significantly less apical debris extrusion.

Abstract Objective: To evaluate the difference in torsional resistance, angular deflection and fragment length between two new rotary instruments: AF Blue S4 and S-One. These files share all features except cross-sectional design. Material and Methods: A total of 40 new Nickel-Titanium instruments of 25 mm in length were tested in this study and divided in two groups: 20 AF Blue S4, tip 25 and constant 6% taper and 20 AF-Blue S4 tip 25 and constant 6% taper. The torsional test was performed by the use of a torque recording endodontic motor (KaVo, Biberac, Germany). Torque to Fracture (TtF), Angular Deflection (AD) and Fragment Length (FL) was recorded for each instrument. To ensure an immovable block at 3mm of the instrument tip, an auto-polymerizing resin (DuraLay; Reliance Dental Mfg Co, Worth, IL) was used. Each file was rotated clockwise at a speed of 300 rpm until fracture occurred. Results: Group A (AF Blue S4) showed higher TtF and AD than Group B (S-One), and statistical analysis found significant differences between the two instruments (p<0.05). The mean values for FL showed no significant differences (p>0.05) between the two instruments. Conclusion: The AF Blue S4 seems to have a higher resistance to torsional stress in vitro. Clinically, the use of AF Blue S4 could be safer in narrow canals.

Abstract Objective To evaluate the efficacy of different sonic and ultrasonic devices in the elimination of debris from canal irregularities in artificial root canals. Materials and Methods A resin model of a transparent radicular canal filled with dentin debris was used. Five groups were tested, namely: Group 1 – ultrasonic insert 15.02; Group 2 – ultrasonic insert 25/25 IRRI K; Group 3 – ultrasonic insert 25/25 IRRI S; Group 4 – sonic insert 20/28 Eddy on a vibrating sonic air-scaler handpiece; Group 5 – 20.02 K-file inserted on a Safety M4 handpiece. Two different irrigants (5% sodium hypochlorite and 17% EDTA) and 3 different times of activation (20, 40, and 60 seconds) were tested. Means and standard deviations were calculated and statistically analyzed with the Kruskal-Wallis and Wilcoxon tests (p<0.05). Results No statistically significant differences were found between the two irrigants used. Group 4 removed more debris than the other groups (p<0.05). Groups 1, 2, and 3 removed more debris than group 5 (p<0.05). A statistically significant difference (p<0.05) was found for the time of activation in all groups and at all canal levels, except between 40 and 60 seconds in group 4 at coronal and middle third level (p>0.05). Conclusions No significant differences were found between 5% sodium hypochlorite and 17% EDTA. When the time of activation rises, the dentin debris removal increases in all groups. Both sonic and ultrasonic activation demonstrate high capacity for dentin debris removal.

Resumo A irrigação do canal radicular é coadjuvante na desinfecção e remoção de debris, contribuindo para o sucesso do tratamento endodôntico. Este artigo apresenta uma visão geral das tecnologias atuais indicadas para melhorar a limpeza e desbridamento do canal radicular. Foi realizado um levantamento bibliográfico eletrônico no site Pubmed utilizando palavras-chave específicas ao tema a fim de abordar literatura relevante. Após busca eletrônica, artigos completos foram revisados e os mais apropriados ao tema foram incluídos nesta revisão. Diferentes sistemas de ativação mecânica foram considerados: agitação manual com cone de guta-percha, instrumentos e escovas endodônticas, sistemas de vibração ativados por peças manuais em baixa rotação ou por energia sônica e subsônica, ultrassom, laser, assim como sistemas de irrigação que utilizam pressão apical negativa. Além disso, esta revisão descreve outros meios indicados para ampliar a descontaminação endodôntica por meio de agentes químicos como ozônio e desinfeção por meio de luz. A ativação ultrassônica do hipoclorito de sódio ainda permanece o padrão ouro e nos estudos é usada como controle na comparação aos demais sistemas que empregam agitação mecânica. A presente revisão mostra vantagens de diversos sistema de irrigação e associações entre eles, podendo aumentar a efetividade da irrigação endodôntica.

Abstract Effective irrigant delivery and agitation are prerequisites to promote root canal disinfection and debris removal and improve successful endodontic treatment. This paper presents an overview of the currently available technologies to improve the cleaning of the endodontic space and their debridement efficacy. A PubMed electronic search was conducted with appropriate key words to identify the relevant literature on this topic. After retrieving the full-text articles, all the articles were reviewed and the most appropriate were included in this review. Several different systems of mechanical activation of irrigants to improve endodontic disinfection were analysed: manual agitation with gutta-percha cones, endodontic instruments or special brushes, vibrating systems activated by low-speed hand-pieces or by sonic or subsonic energy, use of ultrasonic or laser energy to mechanically activate the irrigants and apical negative pressure irrigation systems. Furthermore, this review aims to describe systems designed to improve the intracanal bacterial decontamination by a specific chemical action, such as ozone, direct laser action or light-activated disinfection. The ultrasonic activation of root canal irrigants and of sodium hypochlorite in particular still remains the gold standard to which all other systems of mechanical agitation analyzed in this article were compared. From this overview, it is evident that the use of different irrigation systems can provide several advantages in the clinical endodontic outcome and that integration of new technologies, coupled with enhanced techniques and materials, may help everyday clinical practice.

The goal of the present article is to illustrate and analyze the applications and the potential of microcomputed tomography (micro-CT) in the analysis of tooth anatomy and root canal morphology. The authors performed a micro-CT analysis of the following different teeth: maxillary first molars with a second canal in the mesiobuccal (MB) root, mandibular first molars with complex anatomy in the mesial root, premolars with single and double roots and with complicated apical anatomy. The hardware device used in this study was a desktop X-ray microfocus CT scanner (SkyScan 1072, SkyScan bvba, Aartselaar, Belgium). A specific software ResolveRT Amira (Visage Imaging) was used for the 3D analysis and imaging. The authors obtained three-dimensional images from 15 teeth. It was possible to precisely visualize and analyze external and internal anatomy of teeth, showing the finest details. Among the 5 upper molars analyzed, in three cases, the MB canals joined into one canal, while in the other two molars the two mesial canals were separate. Among the lower molars two of the five samples exhibited a single canal in the mesial root, which had a broad, flat appearance in a mesiodistal dimension. In the five premolar teeth, the canals were independent; however, the apical delta and ramifications of the root canals were quite complex. Micro-CT offers a simple and reproducible technique for 3D noninvasive assessment of the anatomy of root canal systems.

L’obiettivo di questo articolo è stato quello di dimostrare la validità della microtomografia computerizzata (micro-CT) per visualizzare, analizzare e studiare l’anatomia dentaria ed endodontica in vitro. Sono stati selezionati 15 differenti elementi dentari umani estratti per motivi ortodontici o parodontali, selezionati tra primi molari dell’arcata superiore con un se-condo canale nella radice mesiovestibolare (MB2), tra primi molari inferiori in cui la radice mesiale avesse un cosiderevole grado di curvatura in senso mesiodistale o tra premolari con una o due radici aventi un’anatomia apicale particolarmente complicata. L’hardware utilizzato per la scansione è stato un micro tomografo computerizzato (SkyScan 1072, SkyScan bvba, Aartselaar, Belgium) mentre il software per la visualizzazione e l’analisi tridimensionale dei dati è stato ResolveRT Amira (Visage Imaging). Gli autori hanno ottenuto le ricostruzioni tridimensionali ottenute da analisi micro-CT di 15 elementi dentari umani estratti. È stato possibile osservare dettagliatamente sia l’anatomia endodontica fine che l’anatomia radicolare esterna degli elementi dentari analizzati. Tra i cinque molari superiori analizzati, in tre casi il canale mesiobuccale secondo (MB2) era confluente con il canale mesiobuccale principale, mentre negli altri due campioni dello stesso elemento analizzati essi erano indimìpendenti con forami apicali separati. Tra i molari inferiori due dei cinque analizzati avevano un unico canale nella radice mesiale di forma estremamente appiattita in senso mesiodistale. Tra gli elementi premolari analizzati, i canali se doppi erano indipendenti ma spesso hanno dimostrato possedere una complicata anatomia apicale con delta e ramificazioni molto intricate. La microtomografia offre una tecnica semplice e riproducibile per l’analisi tridimensionale non invasiva dell’anatomia endodontica.

The goal of the study is to evaluate if the use of rotary nickel-titanium (RNT) instruments, as Hedstroem files, is safe. Twelve twisted files (TF) RNT instruments size 06-25 were selected and randomly divided in 2 groups of 6 instruments each. Group A (new instruments) were used as control. Group B (test) instruments were clinically used only as Hedstroem files in a canal that had been previously instrumented to the working length with other 06-25 RNT instruments. Group B instruments were used only in the straight portion of the canal (1 minute at 1000 rpm). A cyclic fatigue test was performed for each instrument of groups. Data were statistically analyzed (Student's t-test). Results showed no significant difference (P > 0.05) between groups A and B. Data confirmed that the use of TF instruments as Hedstroem files is a safe procedure. Cross section images and volumes of the same instrument, before and after cyclic fatigue testing, have been obtained by means of microtomographic analysis to evaluate possible microstructure alterations.

Scopo dello studio è valutare se l'utilizzo degli strumenti rotanti nichel titanio come Hedstroem file è sicuro. Dodici twisted files (TF), dimensioni 06-25, sono stati selezionati e suddivisi random in 2 gruppi di 6 strumenti ciascuno. Il gruppo A (strumenti nuovi) composto da strumenti utilizzati come controllo. Il gruppo B (test) composto da strumenti utilizzati, clinicamente solo come Hedstroem file in un canale, in precedenza strumentato fino alla lunghezza di lavoro con altri strumenti rotanti 06-25. Gli strumenti del gruppo B sono stati utilizzati soltanto nella porzione rettilinea del canale (1 minuto a 1000 rpm). È stato eseguito un test di fatica ciclica sugli strumenti dei due gruppi. I dati sono stati analizzati statisticamente (Student's t-test). I risultati non mostrano differenze statisticamente significative (P > 0,05) tra i due gruppi. I dati raccolti hanno confermato che l'utilizzo dei TF come Hedstroem file rappresenta una procedura sicura. Tramite analisi microtomografica sono state ottenute delle immagini di sezioni e volumi dello stesso strumento, prima e dopo l'applicazione di fatica ciclica, per valutare eventuali alterazioni microstrutturali.

A new manufacturing method of twisting nickel titanium wire to produce rotary nickel titanium (RNT) files has recently been developed. The aim of the present study was to evaluate whether the new manufacturing process increased the angular deflection of RNT files, by comparing instruments produced using the new manufacturing method (Twisted Files) versus instruments produced with the traditional grinding process. Testing was performed on a total of 40 instruments of the following commercially available RNT files: Twisted Files (TF), Profile, K3 and M2 (NRT). All instruments tested had the same dimensions (taper 0.06 and tip size 25). Test procedures strictly followed ISO 3630-1. Data were collected and statistically analyzed by means ANOVA test. The results showed that TF demonstrated significantly higher average angular deflection levels (P<0.05), than RNT manufactured by a grinding process. Since angular deflection represent the amount of rotation (and consequently deformation) that a RNT file can withstand before torsional failure, such a significant improvement is a favorable property for the clinical use of the tested RNT files.

Recentemente è stato sviluppato un nuovo metodo di costruzione degli strumenti endodontici rotanti (RNT), attorcigliando filamenti di nickel e titanio. Lo scopo del presente studio è stato quello di valutare se il nuovo metodo di produzione incrementa la deflessione angolare degli strumenti rotanti endodontici, comparando quelli prodotti con il nuovo processo di produzione con quelli realizzati con metodiche tradizionali di tornitura. Le prove sono state eseguite su un totale di 40 strumenti dei seguenti commercialmente reperibili: Twisted Files (TF), Profile, K3 e M2. Tutti gli strumenti sottoposti alle prove erano delle stesse dimensioni (taper 0.06 and tip size 25). Le procedure di prova hanno seguito fedelmente quanto indicato nella normativa ISO 3630-1. I dati ottenuti sono stati analizzati statisticamente tramite il test ANOVA. I risultati hanno mostrato che gli strumenti TF presentano un livello di deflessione angolare più elevato (P<0.05) di quelli RNT costruiti con processo di tornitura. Poiché la deflessione angolare rappresenta la quantità di rotazione (e di conseguenza di deformazione) che uno strumento RNT può sopportare prima della rottura a torsione, un tale significativo miglioramento rappresenta una caratteristica auspicabile per l'uso clinico degli strumenti endodontici esaminati nell'ambito di questo studio.