Does the use of fiber posts increase the fracture resistance of simulated immature teeth? A systematic review.

This systematic review aimed to assess if the use of fiber posts reinforces weakened immature teeth. A systematic review was conducted of laboratory studies that evaluated the fracture resistance of simulated immature teeth restored with fiber posts compared to teeth restored exclusively with resin. An electronic search was performed using the following databases: PubMed/MEDLINE, Web of Science, Scopus and LILACS, BBO, and grey literature. Two independent researchers screened the titles and abstracts of the retrieved studies for relevance to the research question. Subsequently, the full texts of potentially relevant studies were screened based on the exclusion criteria. Ten out of 1792 unique records were included in this systematic review. Risk of bias was assessed using an adapted tool based on the Cochrane risk of bias tool. The laboratory studies included in this systematic review were performed on both human and bovine teeth. Eight studies concluded that fiber posts reinforce the structure of weakened roots, and two studies reported that fiber posts did not strengthen the radicular structure compared to teeth exclusively restored with resin composite. The highly heterogeneous data made it challenging to synthesize the results into a summary estimate, and thus no meta-analysis was undertaken. A summary effect could not be estimated without a meta-analysis. Although the laboratory literature suggests that fiber posts reinforce the structure of immature teeth, the results should be interpreted with caution, as most of the studies had an unclear or high risk of bias.

Bacterial Reduction in Oval-Shaped Root Canals After Different Irrigant Agitation Methods.

OBJECTIVE: This study aimed to assess the antibacterial effect of Easy Clean®, passive ultrasonic irrigation and sonic irrigation against Enterococcus faecalis biofilm in oval-shaped canals. METHODS: Fifty-five extracted human teeth with similar dimensions were selected. Access cavities were prepared and the root canals were instrumented using Wave One® Primary files (25.08). The root canals were then contaminated with an E. faecalis suspension following incubation for thirty days. The contaminated roots were divided into three experimental groups (n=15) according to the irrigant agitation protocol (Easy Clean, passive ultrassonic irrigation and sonic irrigation), in addition to a positive control group (n=5) and a negative control group (n=5). Microbiological samples were taken from the root canals before instrumentation (S1), after instrumentation (S2) and after the final irrigation protocol (S3). The samples were assayed and incubated for 48 hours in order to obtain the residual titer of E. faecalis cells. Viable cells were quantified by colony-forming units (CFU) measurement. The collected data was submitted to statistical analysis by using Shapiro-Wilk`s test, Wilcoxon paired test, Kruskal-Wallis test and Dunn's post-hoc test. The level of significance was set at 5%. RESULTS: All experimental groups presented significant reduction on bacterial load after instrumentation (P<0.05) with similar reduction among the groups. After the agitation protocols, significant reduction in bacterial load was demonstrated for all groups (P<0.05). However, no differences were shown among Easy Clean®, PUI and SI (P>0.05). CONCLUSION: The results showed that all tested groups exhibited similar disinfection effectiveness. However, none of them was able to render all root canals free from microorganisms.

In vitro analysis of microbial contamination of paper points

Introduction: During endodontic treatment, the maintennance of the aseptic chain is mandatory. Therefore, all substances, instruments, and medications inserted into root canals must be free of microorganisms. Objective: To evaluate in vitro and microbiologically the contamination of absorbent paper points. Material and methods: Absorbent paper points of different brands and under different conditions were evaluated and subdivided into the following groups: esterilized by the manufacturer (G1 to G5), not esterilized by the manufacturer (G6), esterilized in autoclave by the operator (G7), and intentionally contaminated (G8). The two last groups were the positive and negative controls, respectively. All paper points were unpacked and immersed into tubes with culture medium for 48 hours and then analyzed according to culture broth turbidity. Results: Only the samples esterilized by the manufacturers Dentsply® (G1), Endopoints® (G2), and Meta® (G3), and the samples esterilized in autoclave by the operator (G7) did not evidence microbial growth after 48 hours. Although sterilized by the manufacturer, both the brands Tanari® (G4) and Roeko® (G5) showed bacterial contamination; Dentsply® (G6) non-sterile paper points also showed bacterial contamination. Conclusion: Paper point esterilization before clinical use should be recommended regardless of the commercial brand.

Efetividade de três soluções na descontaminação de cones de guta-percha e de resilo / Effectiveness of three solutions in disinfection of gutta-percha and resilon pellets

O objetivo deste trabalho foi verificar a efetividade na descontaminação de cones de guta-percha e de resilon com os seguintes grupos: hipoclorito de sódio 5,25% durante 1 minuto; hipoclorito de sódio 2,5% durante 1 minuto; clorexidina 2% durante 1 minuto; glicerina fenicada durante 24 horas. Os agentes apresentaram-se eficazes, sem diferença estatística significativa, embora a clorexidina a 2% tenha apresentado um percentual de 20% de amostras positivas tanto na guta-percha como no resilon, o que pode ser considerado relevante clinicamente. Concluiu-se que o hipoclorito de sódio e a glicerina fenicada podem ser indicados para a descontaminação de ambos os tipos de cone, nas duas concentrações testadas.

The aim of this study was to assess the effectiveness in decontamination of gutta-percha and Resilon with the following groups: 5.25% sodium hypochlorite for 1 minute; 2.5% sodium hypochlorite for 1 minute, 2% chlorhexidine during 1 minute; glycerin fenicada for 24 hours. The agents had been effective, not statistically significant, although the 2% chlorhexidine presented a higher percentage of 20% of positive samples in both the gutta-percha and Resilon in what can be considered clinically relevant. It was concluded that sodium hypochlorite and glycerin fenicada may be indicated for the decontamination of both types of cone, at the concentrations tested.

Influence of different manufacturing methods on the cyclic fatigue of rotary nickel-titanium endodontic instruments.

INTRODUCTION: The aim of this study was to evaluate, by static and dynamic cyclic fatigue tests, the number of cycles to fracture (NCF) 2 types of rotary NiTi instruments: Twisted File (SybronEndo, Orange, CA), which is manufactured by a proprietary twisting process, and RaCe files (FKG Dentaire, La Chaux-de-Fonds, Switzerland), which are manufactured by grinding. METHODS: Twenty Twisted Files (TFs) and 20 RaCe files #25/.006 taper instruments were allowed to rotate freely in an artificial curved canal at 310 rpm in a static or a dynamic model until fracture occurred. RESULTS: Measurements of the fractured fragments showed that fracture occurred at the point of maximum flexure in the midpoint of the curved segment. The NCF was significantly lower for RaCe instruments compared with TFs. The NCF was also lower for instruments subjected to the static test compared with the dynamic model in both groups. Scanning electron microscopic analysis revealed ductile morphologic characteristics on the fractured surfaces of all instruments and no plastic deformation in their helical shafts. CONCLUSIONS: Rotary NiTi endodontic instruments manufactured by twisting present greater resistance to cyclic fatigue compared with instruments manufactured by grinding. The fracture mode observed in all instruments was of the ductile type.

Resistência à flexocompressão de instrumentos endodônticos indicados para canais atresiados e sua correlação com as características morfométricas / Buckling resistance of pathfinders and its geometry

O objetivo deste estudo foi avaliar a resistência à flexocompressão (flambagem) de instrumentos endodônticos empregados no cateterismo de canais radiculares atresiados e se esta varia conforme o comprimento. Flambagem é a deformação lateral apresentada por um instrumento quando submetido a uma força compressiva na direção de seu longo eixo. Foram utilizados instrumentos endodônticos C+File nº 10, K-File nº 10 (Dentsply-Maillefer, Suíça); CC+ nº 10 e C-Pilot nº 10 (VDW, Alemanha), HI-5 nº 10 (Miltex, EUA), Pathfinder CS K2 e Pathfinder SS (SybronEndo, EUA), sendo dez amostras de cada marca comercial em diferentes comprimentos. As dimensões dos instrumentos, tais como diâmetros, comprimento útil, comprimento da parte de trabalho, conicidades, ângulos de inclinação das hélices, ângulo da ponta, forma de seu vértice e presença de ângulo de transição foram determinadas por meio de um microscópio óptico com dispositivo micrométrico acoplado a um computador (Pantec, Panambra, Brasil). Detalhes da forma das pontas e forma das seções retas transversais foram obtidas por meio de um microscópio eletrônico de varredura (MEV - JEOL, JSM-5800, Tókio, Japão). O ensaio de flambagem foi realizado empregando-se uma máquina de ensaio universal (EMIC, DL 10.000, Paraná) e consistiu na aplicação de uma força crescente na direção axial dos instrumentos avaliados, sendo registrada por um software até o deslocamento de 1 mm. A análise dos resultados pelo ANOVA e Tukey revelou que a força máxima para flambar os instrumentos foi maior para os da marca comercial C+File tendo os instrumentos Pathfinder SS apresentado os resultados menos favoráveis. Provavelmente a geometria, que se mostrou completamente distinta para cada grupo de instrumentos, influenciou no comportamento dos mesmos, embora o comprimento não tenha interferido na resistência à flexocompressão.

The aim of this study was to evaluate the buckling resistance of endodontic intruments during the pathfinding of constricted root canals and its lenght influence. Buckling is the elastic deformation of an instrument due to the compressive strenght in its axial direction. The instruments surveyed and tested were: C+File #10, K-File #10 (Maillefer, Switerzland), CC+#10, C-Pilot #10 (VDW, Germany), HI-5 #10 (Miltex, USA) and Pathfinder CS K2 and SS (SybronEndo, USA). Ten instruments from different brands with different lenghts were measured through a optical microscope (Pantec, Panambra, Brazil) aiming to register the diameters, total and useful lenght, taper, helical angles and tip angle, whereas tip details and cross sections were obtained through an electronic microscope MEV (JEOL, JSM-5800). The buckling test was performed at an universal testing machine (EMIC, DL 10.000, Brazil). The maximum load during the elastic deformation was measured by a software while applying increasingly pressure in the axial direction of each instrument till a 1mm deformation. The ANOVA e Tukey test analized the results and revealed that the C+File presented the highest buckling resistance while Pathfinder SS presented the worst results. Different designs might interfere with the results but, in general, the lenght did not have statistical influence.

Resistência à flambagem de instrumentos endodônticos empregados no cateterismo de canais radiculares atresiados / Resistence to buckling of the endodontic instruments used in the catherism of the partially calcified root canals

Este estudo analisa a forma de trabalho, as dimensões e a resistência à flambagem de instrumentos endodônticos empregados no caterismo de canais radiculares etresiados. Foram analisados instrumentos C+File, Colorinox e Nitiflex da Dentisply-Maillefer, CC Cord da Antaeos e HI da Miltex. As dimensões foram determinadas no projetor de perfil. As formas foram obtidas no MEV. A resistência à flambagem foi quantificada pela aplicação de uma força na direção axial dos instrumentos. Concluiu-se que os instrumentos C+File apresentaram formas e dimensões diferentes. Os instrumentos C-File apresentam maior resistência à flambagem seguidos pelo CC Cord.

Avaliação da capacidade de corte de limas tipo K de aço inoxidável e de níquel-titânio / Evaluation of machning efficiency of staineless steel and nickel-titanium K-files

O objetivo deste trabalho foi avaliar a capacidade de corte de limas endodônticas tipo K de aço inoxidável(Flexofile - Maillefer) e de níquel-titânio (Nitiflex - Maillefer) em comprimentos de 21mm ou 25mm. Os ensáios foram realizados empregando-se um dispositivo mecânico capaz de criar um movimento linear aplicado aos instrumentos endodônticos sobre placas de osso bovino. A avaliação da capacidade de corte baseou-se na mensuração das profundidades dos desgastes de caneletas previamente obtidas nos bordos das placas ósseas. Os resultados mostraram diferença significante entre a capacidade de corte das limas Nitiflex e a das Flexofile, sendo as de NiTi mais efetivas. Não houve, porém, influência quanto ao comprimento da lima. Em todos os grupos ensaiados ocorreu decréscimo do rendimento de corte com uso, sendo essa perda mais efetiva do primeiro para o segundo uso