Using manual versus mechanized glide path instruments and ProTaper Gold versus ProTaper Next systems in curved canals: micro-CT study

Abstract The aim of this study was to evaluate the root canal shaping effect of ProTaper Gold (PTG) versus ProTaper Next (PTN) instrumentation systems, and of a manual #15 K-type file (K15) versus the ProGlider (PG) mechanized instrument for glide path creation, in severely curved mesial canals. Twenty-four mandibular molars with two separate mesial canals were anatomically matched using computed tomographic scanning, and then divided into two groups (n=12) according to the glide path instrument used, either K15 or PG. In all teeth, the PTG system was used to prepare the mesiobuccal canal, and the PTN, the mesiolingual canal. The teeth were scanned by computed microtomography, before and after root canal preparation, and the values of the initial volume, final volume, volumetric variation, untouched walls, and canal transportation variables were determined. The data were analyzed using the two-way ANOVA test, and the Tukey test for multiple comparisons. There was no significant difference among the study groups regarding volumetric variation or root canal transportation, either in the cervical, middle or apical thirds, or in the entire root canal (p>0.05). In the apical third, the percentage of untouched walls was significantly higher in groups using K15 than in those using PG (p<0.05), namely 33.144% and 23.285%, respectively, irrespective of the instrumentation system. In the other regions, there was no difference between K15 and PG regarding this variable. It was concluded that PG was associated with a lower rate of untouched walls in the apical region than K15.

Cyclic fatigue resistance of three reciprocating nickel-titanium instruments with heat treatment at intrachannel temperature

Introduction: the in vitro study compared the dynamic cyclic fatigue resistance of 3 reciprocating NiTi files with heat treatment. Methods: we distributed 30 new endodontic files in three groups. The endodontic files selected for this experiment were: AF Blue R3 25/06 (AFB) (Fanta Dental, Shanghai, China), X1 Blue File 25/06 (X1B) (MK Life, Porto Alegre, RS, Brazil), and Reciproc Blue 08/25 (RB) (VDW, Munich, Germany. We measured the time to file fractureand the length of the fractured fragment. ANOVA analysis was used, followed by the Tukey test for multiple comparisons, with a significance level of 5% (P < 0,05). Results: the mean time in seconds until the file fractured was 170.7 ±15,1 for AFB files, 110,4 ±26,8 for X1B, and 163,3 ±22,9 for RB files. This difference was statistically significant when comparing X1B to AFB (p: 0,000) and X1B to RB (p: 0,000). However, there are no statistically significant differences between RB and AFB (p:0,739). Conclussions: this study found that RB and AFB files exhibit similar resistance to cyclic fatigue.

Introducción: el estudio in vitro comparó la resistencia a la fatiga cíclica dinámica de 3 limas NiTi recíprocas con tratamiento térmico. Métodos: distribuimos 30 limas endodónticas nuevas en tres grupos. Las limas endodónticas seleccionadas para este experimento fueron: AF Blue R3 25/06 (AFB) (Fanta Dental, Shanghai, China), X1 Blue File 25/06 (X1B) (MK Life, Porto Alegre, RS, Brasil), y Reciproc Blue 08/25 (RB) (VDW, Munich, Alemania. Se midió el tiempo transcurrido hasta la fractura de la lima y la longitud del fragmento fracturado. Se utilizó el análisis ANOVA, seguido de la prueba de Tukey para comparaciones múltiples, con un nivel de significación del 5% (P < 0.05). Resultados: el tiempo medio en segundos hasta la fractura de la lima fue de 170.7 ±15.1 para las limas AFB, 110.4 ±26.8 para las X1B y 163.3 ±22.9 para las RB. Esta diferencia fue estadísticamente significativa al comparar X1B con AFB (p: 0.000) y X1B con RB (p: 0.000). Sin embargo, no hay diferencias estadísticamente significativas entre RB y AFB (p:0.739). Conclusiones: en este estudio se ha comprobado que las limas RB y AFB presentan una resistencia similar a la fatiga cíclica.

Análisis microbiológico a corto y largo plazo del material usado para esterilizar instrumental odontológico / Short and long-term microbiological analysis of the material for sterilize dental instruments

Introducción: el material para empaquetar el instrumental odontológico, como pueden ser bolsas de tela, papel o plástico, es usado por profesionales de la salud; sin embargo, es necesario esclarecer la efectividad de cada uno y determinar el tiempo que permanece estéril luego del procedimiento. Objetivo: identificar la eficacia de tela, plástico y papel como materiales para esterilizar instrumental a corto y largo plazo. Material y métodos: se realizaron cultivos sólidos y líquidos de instrumental esterilizado en tres materiales y con diferentes tiempos de postesterilización. Se incubaron a 36 oC por 72 horas en condiciones aerobias y anaerobias. Los resultados se analizaron usando una prueba de Kruskal-Wallis, seguida de una prueba de Dunn. Resultados: los resultados mostraron que inmediatamente después del proceso de esterilización, los tres materiales son efectivos (Kruskal-Wallis test, p = 0.2752), 24 horas (p = 0.2492), siete (p = 0.0509) y 14 días (p = 0.0006). Veinticuatro horas posterior a la esterilización la tela no es efectiva, el plástico disminuye su efectividad y el papel sigue siendo efectivo. Conclusión: en nuestros resultados, el papel es la mejor opción para esterilizar instrumental (AU)

Introduction: material such as cloth, paper or plastic bags to wrap dental instruments is used by health professionals, however, it is necessary to clarify the effectiveness of each one and determine if it remains sterile after the procedure. Objective: to determine the effectiveness of cloth, plastic and paper as materials to sterilize dental instruments in the short and long term. Material and methods: we carry out solid and liquid cultures of sterilized instruments in three materials, at different post-sterilization times, incubated at 36 oC for 72 hours under aerobic and anaerobic conditions, and the results were analyzed using a Kruskal-Wallis test, followed by from a Dunn's test. Results: our results showed that immediately after the sterilization process the three materials are effective (Kruskal-Wallis; p = 0.2752), 24 hours (p = 0.2492), 7 (p = 0.0509) and 14 (p = 0.0006) days. Twenty-four hours after the cloth is not effective, plastic decreases its effectiveness and paper remain effective. Conclusion: in our results, paper is the best option to sterilize dental instruments (AU)

Influence of traverse and waveone gold glider glide path files on the amount of apically extruded debris / Influência das limas glide path Traverse e Wave One Gold Glider na quantidade de detritos extruídos apicalmente

Objective: The aim of this study was to evaluate the effect of different glide path files on the amount of apically extruded debris. Material and Methods: Sixty single-canaled mandibular premolars were accessed and randomly divided into three groups (n= 20) according to the file used for glid path creation; group A using Traverse file, group B using WaveOne Gold Glider, group C using stainless steel K file. All teeth were then instrumented using the Reciproc system. The debris extruded apically during instrumentation were collected into pre-weighed Eppendorf tubes which were then stored in an incubator at 70 °C for 5 days. The weight of the dry extruded debris was established by subtracting the pre-instrumentation and post instrumentation weights of the Eppendorf tubes. The data were analyzed using one-way ANOVA test, and post hoc analysis. Results: WaveOne Gold Glider produced the least amount of apical extruded debris (0.41±0.25) followed by the Traverse group (0.59±0.20) then the K-file group (0.64±0.16) with a statistically significant difference (p=0.003). Conclusion: Apical extrusion of debris is inevitable during root canal cleaning and shaping. Creation of glide path using engine-driven files produces less amount of apically extruded debris compared to hand-driven K-files. (AU)

Objetivos: O objetivo deste estudo foi avaliar o efeito de diferentes limas glide path na quantidade de detritos extruídos apicalmente. Metodologia: Sessenta pré-molares inferiores com canal único foram acessados e divididos aleatoriamente em três grupos (n= 20) de acordo com a lima utilizada para criação do glid path; grupo A usando lima Traverse, grupo B usando WaveOne Gold Glider, grupo C usando lima K de aço inoxidável. Todos os dentes foram então instrumentados usando o sistema reciprocante. Os detritos extruídos apicalmente durante a instrumentação foram coletados em tubos Eppendorf pré-pesados que foram então armazenados em uma incubadora a 70°C por 5 dias. O peso dos detritos secos extruídos foi estabelecido subtraindo-se os pesos dos tubos Eppendorf antes e após instrumentação. Os dados foram analisados por meio do teste one-way ANOVA e análise post-hoc. Resultados: WaveOne Gold Glider produziu a menor quantidade de detritos apicais extruídos (0,41±0,25) seguido pelo grupo Traverse (0,59±0,20) e depois pelo grupo K-file (0,64±0,16) com uma diferença estatisticamente significativa (p=0,003). Conclusão: A extrusão apical de detritos é inevitável durante a limpeza e modelagem do canal radicular. A criação do glide path usando limas acionadas por motores produz menos quantidade de detritos extruídos apicalmente em comparação com as limas K manuais. (AU)

Tactile perception of roughness to assess activity in artificial initial caries lesions with a novel force-controlled probe

Abstract Roughness-tactile perception is part of activity assessment in initial-caries-lesions. Hypothesizing that a probe's design influences this examiner's assessment, four probes were designed. The aims of this study were to select the probe with highest inter-/intra-examiners' roughness-assessment agreement and to determine its diagnostic accuracy on artificial initial-caries lesions. A pilot study was conducted with trained dentists to select one controlled-pressure probe design (n = 4) by assessing roughness on known-roughness metal plaques with 5-point Likert scale. Diagnostic accuracy of roughness assessment was conducted with the selected controlled-pressure probe and the WHO-probe on sound and artificial initial-caries-lesion (n = 20) human enamel blocks. Intra-class correlation coefficients (ICCs) and quadratic weighted-Kappa scores were used to assess examiners' reproducibility and Multilevel Poisson models to determine diagnostic accuracy between both probes controlling for confounding variables. The probe design with the highest inter/intra-examiner's agreement (ICC = 0.96) was selected for subsequent analyses. Unadjusted sensitivity, specificity and accuracy values were for the controlled-pressure and the WHO probes: 71.1%,90.6%,81.2%, and 67.4%,84.6%,75.8%, respectively (p > 0.05). Examiner remained the most important factor influencing diagnostic accuracy. While this study did not show significantly higher diagnostic accuracy of the designed controlled-pressure vs. the WHO-probe when used by trained dentists, all over roughness-assessment accuracy and reproducibility were high.

Effect of nickel-titanium alloys on root canal preparation and on mechanical properties of rotary instruments

Abstract The aim of this study was to evaluate the quality of curved root canal preparation, torsional fatigue, and cyclic fatigue of rotary systems manufactured with different NiTi alloys. Ninety single-rooted canals with curvatures of 15° to 30o were scanned and divided into three groups according to the rotary system used: BT-Race (BTR) - 10.06, 35.00, 35.04; SequenceRotaryFile (SRF) - 15.04, 25.06, 35.04; and ProDesignLogic (PDL) - 25.01, 25.06, 35.05. Each system was used on three specimens. The teeth were prepared, scanned, and analyzed to assess increase in volume, transportation, and centering ability of the root canal. Torsional fatigue of glide path instruments (BTR 10.06, SRF 15.04 and PDL 25.01) and cyclic fatigue of the finishing instrument (BTR 35.04, SRF 35.04 and PDL 35.05) were obtained by analyzing completely new instruments (n = 10) and instruments after they had been used three times (n = 10). After the torsional and cyclic fatigue tests, the fractured surface of the new and used instruments were examined by scanning electron microscopy. Increase in volume, canal transportation, and centering ability showed no significant differences among the groups (p > 0.05). The torsional test showed that SRF 15.04 produced the highest torque values for both new and used instruments, followed by PDL 25.01 and BTR 10.06 (p < 0.05). PDL 25.01, both new and used, exhibited higher values of angular deflection followed by SRF 15.04 and BTR 10.06 (p < 0.05). As regards cyclic fatigue, use of PDL 35.05, both new and used, required a longer time and larger number of cycles than did SRF 35.04 and BTR 35.04 (p < 0.05). Clinical use affected the torsional fatigue of BTR; however, cyclic fatigue was not significantly affected (p < 0.05). All rotary systems were able to prepare the curved canals satisfactorily and were used safely on the three specimens. Relative to torsional fatigue, SRF 15.04 exhibited a higher torque, and PDL 25.01, higher angular deflection. BTR 10.06 was the most affected by clinical use. PDL 35.05 showed greater resistance to cyclic fatigue.

EVALUATION OF ENDODONTIC FILES USED BY UNDERGRADUATED STUDENTS' CONTAMINATION, AFTER CLEANING AND STERILIZATION

Introduction: A thorough endodontic files decontamination protocol, prior to sterilization, is extremely important. Retentions existing in the files active part hinder asepsis, and inadequate cleaning interferes with the sterilization process. Thus, the aim of this study was to evaluate the endodontic files contamination used by undergraduate students from the University Southern Santa Catarina (Unisul), after cleaning and sterilization process. Materials and Methods: Dentistry undergraduate students from the 6th to the 10th period at Unisul, Pedra Branca unit, participated in the research. Endodontic files, caliber # 40, # 45 or # 50, were collected from the sterile metal box and then incubated in a broth culture medium, at 37ºC, in aerobiosis. After 48 hours, the culture medium was evaluated for turbidity, which would indicate the instrument contamination. The total number of contaminated samples for each period was computed and the data statistically analyzed by the chi-square test (α = 5%). Results: A total of 98.46% of the files were sterile. Only 1 file, from a 10th period student, showed contamination. There was no association between the contamination presence and course period (P > 0.05). Conclusion: The endodontic files cleaning and sterilization process is being carried out effectively by dentistry undergraduate students from the 6th to the 10th period at Unisul, Pedra

Resistance to fracture due to cyclic fatigue of stainless steel manual files and its association to surface roughness / Resistencia a la fractura por fatiga cíclica de las limas manuales de acero inoxidable y su relación con la rugosidad superficial

ABSTRACT The aim of this study was to evaluate the possible association between the roughness of 5 brands of stainless steel endodontic files and their resistance to fracture due to cyclic fatigue. The study includedfive different brands of stainless steel endodontic files: SybroEndo Triple-Flex Files (Kerr, Glendora, USA), Ready Steel K-Flexofile (Dentsply Sirona, Ballaigues, Switzerland), Mani Flexile Files (Mani, Tochigi- Ken, Japan), FKG K-Files (FKG, La Chaux-de-Fonds, Switzerland) and Zipperer Flexicut Files (VDW, Munich, Germany). Twelve files per brand (total 60 files) were evaluated. File surface roughness over an area (Sa) was quantified using a focus variation microscope. Then the files were subject to a cyclical fatigue test to determine the number cycles to fracture due to fatigue and length of fractured fragment. Finally, fractographic analysis was performed using a scanning electron microscope. The electropolished Ready Steel K-Flexofile® files had the highest roughness according to Sa parameters, though they also had the highest resistance to fracture due to cyclic fatigue and the longest fractured fragment. Moderate positive correlation was found between fractured fragment length and roughness. The fractured surface showed characteristics of ductile fracture with cracks and plastic deformation. The electropolished stainless steel Ready Steel K-Flexofile® files werethe most resistant to fracture due to cyclic fatigue even though they had highest surface roughness.

RESUMEN El objetivo del presente estudio fue evaluar la posible asociación entre la rugosidad de 5 marcas de limas endodónticas de acero inoxidable y su resistencia a la fractura por fatiga cíclica. Se incluyeron cinco grupos diferentes de limas endo-dónticas de acero inoxidable: SybroEndo Triple-Flex Files (Kerr, Glendora, EE. UU.), Ready Steel K-Flexofile (Dentsply Sirona, Ballaigues, Suiza), Mani Flexile Files (Mani, Tochigi-Ken, Japón), FKG K-Files (FKG, La Chaux-de-Fonds, Suiza) y Zipperer Flexicut Files (VDW, Munich, Alemania); se evaluaron doce instrumentos por grupo para un total de 60 limas. Mediante un microscopio de variación focal se cuantificó la rugosidad superficial por área (Sa) de los instrumentos, posteriormente fueron sometidos a una prueba de fatiga cíclica donde se determinó el número de ciclos de fractura por fatiga y la longitud del fragmento fracturado. Finalmente, se realizó un análisis fractográfico mediante microscopía electrónica de barrido. Las limas Ready Steel K-Flexofile® con electropulido mostraron el mayor valor de rugosidad en los parámetros Sa; sin embargo, también tenían la mayor resistencia a la fractura por fatiga cíclica y la mayor longitud del fragmento fracturado del instrumento. Además, se encontró una correlación moderada positiva entre la longitud del fragmento fracturado y la rugosidad. La superficie fracturada mostró características de fractura dúctil con grietas y deformación plástica. Las limas Ready Steel K-Flexofile® fabricadas en acero inoxidable con electropulido, fueron más resistentes a la fractura por fatiga cíclica a pesar de tener la mayor rugosidad superficial.

Avaliação da resistência à fadiga cíclica e torcional de quatro instrumentos rotatórios de NiTi com secções transversais semelhantes e diferentes tratamentos térmicos / Cyclic and torsional fatigue resistance of four rotary NiTi instruments with similar cross-sectional design and different thermal treatments

Objetivo: O objetivo do presente trabalho foi avaliar a resistência à fadiga cíclica e torcional de instrumentos rotatórios de níquel-titânio com secções transversais semelhantes e confeccionados com diferentes tipos de tratamentos térmicos: Hyflex CM (HCM 25/.06), Vortex Blue (VB 25/.06), Sequence Rotary File (SRF 25/.06) e EdgeSequel (EDF 25/.06) (n=20). Métodos: O teste de fadiga cíclica avaliou o tempo e o número de ciclos para a fratura (NCF) dos instrumentos em canal artificial com 60° de curvatura e 5mm de raio (n=10). O teste de torção avaliou o torque máximo e a deflexão angular para a fratura dos 3mm da ponta dos instrumentos (n=10). Após o teste de torção e de fadiga cíclica, os instrumentos foram avaliados em microscopia eletrônica de varredura (MEV) (n=10). Os dados foram analisados empregando-se os testes ANOVA e de Tukey, sendo selecionado um nível de significância de 5%. Resultados: HCM apresentou o maior tempo e NCF entre todos os instrumentos avaliados (p<0,05). O SRF apresentou um tempo semelhante (p>0,05) e menor NCF (p<0,05) do que o VB. Em relação ao teste torcional, o HCM apresentou menor valor de torque e maior deflexão angular entre os grupos avaliados (p<0,05). Não houve diferenças significativas entre VB, SRF e EDF em relação à deflexão angular (p>0,05). Conclusão: O HCM apresentou maior resistência à fadiga cíclica e deflexão angular. Entretanto, o VB apresentou maior resistência torcional para a fratura (AU).

Objective: The aim of this study was to evaluate the cyclic and torsional fatigue resistance of Nickel-Titanium rotary instruments with similar cross-sectional design and manufactured by different thermal treatments: Hyflex CM (HCM 25/.06) Vortex Blue (VB 25/.06), Sequence Rotary File (SRF 25/.06) and EdgeSequel (EDF 25/.06) (n=20). Material and Methods: Cyclic fatigue test evaluated the time and number of cycles to failure (NCF) in an artificial stainless steel canal with 60° and 5-mm radius of curvature (n=10). The torsional test (ISO 3630-1) evaluated he maximum torque and distortion angle to failure at 3 mm from the tip (n=10). After the torsional and cyclic fatigue test the instruments were evaluated by scanning electron microscope (SEM). Data were analyzed using one-way ANOVA and Tukey tests, and the level of significance was set at 5%. Results: The HCM presented the longest time and highest NCF to fatigue than all the groups (P<0.05). The SRF presented similar time (P>0.05) and lower NCF (P<0.05) to fatigue than VB. Regarding to the torsional test, HCM presented the lowest torque load and the highest distortion angle of all the groups (P<0.05). No significant difference was found among VB, SRF and EDF regarding the distortion angle (P>0.05). Conclusion: The HCM presented the highest cyclic fatigue resistance and distortion angle to failure. However, the VB showed higher torsional load to failure. (AU).

Evaluation of type of kinematics on glide path procedures and torsional fatigue resistance after preparation of moderately curved canals

Abstract: Sixty moderately curved canals of mandibular molars classified as Vertucci's type IV canal configuration were selected by micro-CT 1174. The teeth were divided into two groups according to the kinematics used, whether reciprocating or rotary motion (n=30, totaling 60 mesial root canals). The instruments used to perform the glide path procedures had identical features (0.15 mm of tip size, 0.04 mm/mm taper, thermal treatment, and square cross-section), but differed in the direction of the cutting blade. The duration of the procedure and the absolute and percentage frequency of the instruments to reach the full working length were recorded. The torsional test (3630-1; 1992) was performed on both used and unused instruments, to evaluate a possible reduction in the torsional resistance when using the glide path procedure. Statistical analysis was performed using the unpaired t-test and the chi-square test, and the level of significance was set at 5%. The type of kinematics used affected the duration of glide path procedures, and the reciprocating motion seemed to induce less torsional stress during glide path procedures.

Analysis of the characteristics of periodontal curettes used for scaling the roof of the furcation by manual versus digital method / Análise das características de curetas periodontais utilizadas para raspagem em teto de furca pelo método manual versus digital

Abstract Introduction The treatment of periodontal disease in multiradicular teeth with furcation involvement is a challenge for dentists, with unpredictable results. Objective To evaluate the characteristics of the active tip of periodontal curettes used for scaling the furcation roof, comparing the manual versus digital method. Material and method Forty-two Pádua Lima (PL) curettes of the Millennium® brand (n = 6 for each model) were evaluated: PL 1-2, PL 3-4, PL 5-6, PLW 1-2, PLW 3-4, PLW 5 -6, and PLF. The following were measured: total length of the coronary face (CTc, millimeters, mm), total length of the lateral face (CTl, mm), width of the coronary face (Lc, mm), and width of the lateral face (Ll, mm). The measurements were performed in duplicate. Result The results showed that weight varied among the curettes (p <0.05), however the handle diameter was similar for all instruments (p> 0.05). Considering that seven different types of curettes were evaluated, the parameters of CTl and Ll showed a statistical difference for all evaluated curettes (7: 7 ratio), with higher values ​​for the caliper method compared to the software (p <0.05). There was a statistically significant difference between assessment methods for CTc and Lc measurements (p <0.05), showing that there was a coincidence of values ​​in the proportion of 4:7 for measurements of CTc and 5:7 for Lc. Conclusion The comparison between methods generally resulted in lower values ​​and greater variation for the digital method, thus favoring the use of the manual method to measure the active tip of periodontal curettes.

Resumo Introdução O tratamento da doença periodontal em dentes multirradiculares com envolvimento de furca tem sido um desafio para os cirurgiões-dentistas, com resultados imprevisíveis. Objetivo Avaliar as características da ponta ativa de curetas periodontais utilizadas para raspagem do teto de furca, comparando o método manual versus digital. Material e método Foram avaliadas 42 curetas de Pádua Lima (PL) da marca Millennium® (n=6 para cada modelo): PL 1-2, PL 3-4, PL 5-6, PLW 1-2, PLW 3-4, PLW 5-6 e PLF. Foram mensurados: comprimento total da face coronária (CTc, milímetros, mm), comprimento total da face lateral (CTl, mm), largura da face coronária (Lc, mm) e largura da face lateral (Ll, mm). As mensurações foram em duplicata. Resultado Os resultados mostraram que o peso variou entre as curetas (p<0,05), porém o diâmetro do cabo foi semelhante para todos os instrumentos (p>0,05). Considerando que foram avaliados sete tipos de curetas diferentes, os parâmetros de CTl e Ll se mostraram com diferença estatística para todas as curetas avaliadas (proporção 7:7), com valores maiores para o método do paquímetro em comparação ao software (p<0,05). Houve diferença estatisticamente significativa entre métodos de avaliação para as medidas de CTc e de Lc (p<0,05), mostrando que houve uma coincidência de valores na proporção de 4:7 para as mensurações de CTc e de 5:7 para Lc. Conclusão A comparação entre métodos resultou, em geral, menores valores e maior variação para o método digital, favorecendo, dessa forma, o uso do método manual para a mensuração da ponta ativa de curetas periodontais.

Effects of clinical use of NiTi reciprocating instruments on cyclic and torsional resistance, and on roughness

Abstrac The aim of the present study was to evaluate the cyclic fatigue, torsional resistance and surface roughness of Reciproc R25 instruments in four different situations, namely as new instruments and as instruments tested after clinical preparation of one, two or three maxillary molars with four root canals. The total time required to perform each root canal preparation was recorded. Cyclic fatigue resistance was determined by the time to fracture using a customized testing device (n = 10 per group). The torsional test evaluated the torque and angle of rotation to failure according to ISO 3630-1 (n = 10 per group). The roughness of the working parts of new and used instruments was evaluated with a profilometer (n = 5 per group). Statistical analysis was performed using one-way ANOVA and Tukey's test. The level of significance was set at 5%. No fractures or deformations were observed after clinical use. Higher preparation time was needed during the third use of the instruments for all root canals (p < 0.05). There were no significant differences among the groups in regard to either cyclic fatigue or torsional resistance (p > 0.05). Regarding the roughness measurements, groove depth was higher on new and one- versus two- or three-maxillary-molar-prepared instruments (p < 0.05). It can be concluded that the clinical use of Reciproc instruments increased preparation time and decreased surface roughness. However, clinical use did not affect the cyclic fatigue or torsional resistance of the Reciproc instruments.

Influence of voxel size on micro-CT analysis of debris after root canal preparation

Abstract: The aim of this study was to assess the influence of micro-computed tomography (micro-CT) voxel size on the evaluation of debris accumulation after passive ultrasonic irrigation (PUI) in curved root canals prepared with rotary nickel-titanium files. Mesial root canals (n = 24) of mandibular molars with curvature between 25° and 35° were prepared using ProDesign Logic 30/.05 (PDL) or HyFlex EDM 25/.08 (HEDM). PUI was performed after root canal preparation of all root canals. The specimens were scanned using high-resolution (5 μm voxel size) micro-CT imaging before and after experimental procedures. The percentage of debris was analyzed in the middle and apical thirds using images with 5, 10 and 20 μm voxel sizes. Data were compared using unpaired and paired Student's t-test, ANOVA and Tukey's statistical tests (α = 0.05). There were no differences among the debris analyses performed at different voxel sizes (5, 10 and 20 μm) (p > 0.05). The percentage of debris was similar between the root canals prepared by PDL and HEDM before and after PUI (p > 0.05). In both groups, the percentage of debris decreased in the middle third after PUI (p < 0.05). Within the limitations of this ex vivo study, it can be concluded that the voxel sizes evaluated did not have a significant impact on the analysis of accumulated debris. However, the results showed a tendency for detection of more debris in the analysis performed using a lower voxel size. PUI decreased the debris accumulation in the middle third of curved root canals.

Comparação do alargamento apical do canal radicular através dos sistemas de instrumentação SAF e Reciproc / Comparison of apical enlargement of the root canal through SAF and Reciproc instrumentation systems

Objetivo: Comparar o aumento percentual da área da secção reta transversal de canais radiculares, no nível de 3 mm aquém do ápice radicular, após instrumentação com dois sistemas de instrumento único. Métodos: Dezenove primeiros molares inferiores extraídos tiveram as raízes mesiais seccionadas no nível de 3 mm aquém do ápice radicular, sendo os 2 milímetros finais de cada raiz removidos e descartados, para proceder a mensuração da área pré-operatória, através de estereomicroscopia. As raízes foram instrumentadas com os sistemas SAF e Reciproc R25.08 e procedeu-se nova mensuração para comparação do aumento percentual da área. O aumento percentual da área da secção reta transversal foi comparado e analisado estatisticamente pelo teste t de Student. O nível de significância foi estabelecido em 5% (p < 0,05). Resultados: O aumento percentual da área dos canais foi significativamente maior para o grupo Reciproc (p = 0,001) em comparação com o grupo SAF. Os canais instrumentados com o sistema SAF tiveram sua área aumentada em média 53,5%, enquanto que nos instrumentados com o sistema Reciproc a média foi 154,5%. Conclusão: O sistema Reciproc proporcionou um aumento percentual da área da secção reta transversal dos canais radiculares, no nível dos 3 mm apicais, 3 vezes maior que o sistema SAF.

Aim: To compare the percentage increase in the cross-sectional area of root canals, at the level of 3 mm from the root apex after instrumentation with two single instrument systems. Methods: The roots of 19 extracted mandibular first molars were sectioned 3 mm short of the apex level, with the final 2 millimeters of each root removed and discarded in order to enable the preoperative area to be measured by stereomicroscopy. Subsequently, the roots were instrumented with the SAF and Reciproc 25/.08 systems, alternating the technique used per canal from root to root, and a new measurement was performed. After, the percentage increase in area was calculated considering the values of the original and the final area. The Student'st-test was applied to the results, with a level of significance set at 5%. Results: The percentage increase in area of the root canals was significantly higher for the Reciproc (p = 0.001) when compared to the SAF group. In the canals instrumented with the SAF system, the mean increase in area was 53.5%, while in those using the Reciproc system, it was 154.5%. Conclusion:The Reciproc system produced a 3-fold higher percentage increase in the cross-sectional area of the root canals at the level of 3 mm from the root apex than did the SAF system.

Accuracy of Root ZXII, E-PEX and FIND apex locators in teeth with vital pulp: an in vivo study

Abstract: This research evaluated, in vivo, the accuracy of three electronic apex locators - EALs (Root ZXII, E-PEX and FIND) in teeth with vital pulp submitted to biopulpectomy, preserving the periodontal stump. For this study, 90 single-rooted teeth with extraction indication were selected. After positive pulpal cold sensitivity test, pulp chamber access was performed. The cervical and middle thirds of root canals were instrumented with Reciproc R25, and the K#15 file was used as a standard instrument to determine working length, forming 2 groups: Constriction (insertion of the instrument until the apical constriction limit) and Foramen (insertion of the instrument until the foramen and then repositioning at constriction, without removing the file from the canal). The hand file was stabilized with a light-cured flow resin. After extraction, the samples were analyzed through microCT SkyScan 1272, with CTAN software, which evaluated the proximity between the tip of the file to the apical constriction, providing data for comparative analysis using Kruskal-Wallis and Dunn tests (p<0.05). There was a statistically significant difference in the abilities of the EALs to detect the apical constriction after reaching the foramen with Root ZX II showing higher accuracy (89%). However, there was no difference in the accuracy of the three EALs in detecting the apical constriction without reaching the foramen. Based on the present results, we conclude that EALs may show accurate measures in detecting apical constriction and foramen, even without damaging the periodontal stump in biopulpectomy.

Remoção de obturações endodônticas de Endosequence BC/CPoint em canais radiculares curvos usando instrumentos rotatórios ou reciprocantes / Removal of Endosequence BC/CPoint endodontic fillings in curved root canals using rotary or reciprocating instruments

Objetivo: O presente estudo usou micro-CT para avaliar a quantidade de material obturador remanescente em canais radiculares curvos que tinham sido obturados com cimento Endosequence BC/Cpoint ou com cimento AH/ guta-percha, depois do retratamento utilizando instrumentos rotatórios ou reciprocantes. Métodos: Sessenta canais mesiovestibulares de molares superiores foram instrumentados até MTwo #35.04. As amostras foram randomicamente alocadas em quatro grupos (n=15): os canais do G1 e G2 foram obturados com AH/guta-percha, e os canais do G3 e G4 foram obturados com BC/Cpoint. O material obturador foi removido usando instrumentos rotatórios ou reciprocantes ­ G1 e G3: R25 Reciproc + reinstrumentação com R40; e G2 e G4: Sistema ProTaper Universal Retratamento + reinstrumentação com MTwo 40.06. Micro-CTs foram usadas para medir a quantidade de material obturador remanescente (mm3 ) para o canal inteiro e para cada terço, em dois momentos: 1) após a remoção do material obturador; e 2) após a reinstrumentação. Resultados: Após a remoção do material obturador, BC/CPoint permaneceu mais dentro do canal do que AH/guta-percha quando o canal inteiro (29,92% x 19,25%, p=0,0290) e o terço apical foram analisados. Após a reinstrumentação, BC/CPoint permaneceu mais do que AH/guta-percha somente no terço apical. Protocolos de tratamento com instrumentos rotatórios ou reciprocantes removeram material obturador sem diferença para AH/guta-percha (G1 e G2: p> 0,05) e BC/CPoint (G3 e G4: p> 0,05). Conclusões: BC/Cpoint é mais difícil de ser removido de canais radiculares curvos do que AH/guta-percha. Instrumentos rotatórios e reciprocantes têm habilidade similar na remoção de material obturador (AU).

Objective: This study used micro-CT to evaluate the amount of remaining filling material in curved root canals obturated with Endosequence BC Sealer/Cpoint or AH/gutta-percha after a rotary or reciprocating retreatment. Methods: Sixty mesiobuccal canals of maxillary molars were instrumented up to MTwo #35.04. Samples were randomly assigned to four groups (n=15): canals from G1 and G2 were filled with AH/gutta-percha, and canals from G3 and G4 were filled with BC/Cpoint. Filling material was removed using rotary or reciprocating instruments: G1 and G3: R25 Reciproc + re-shaping with R40; and G2 and G4: ProTaper Universal Retreatment system + re-shaping with MTwo 40.06. Micro-CT was used to measure the remaining amount of filling material (mm3 ), for the whole canal, and for each third, in two moments: 1) after filling removal and 2) after canal re-shaping. Results: After filling removal, BC/CPoint remained more into the canal than AH/Gutta-percha when the whole canal (29.92% x 19.25%, p = 0.0290) and the apical third were analyzed. After re-shaping, BC/CPoint remained more than AH/Gutta-percha only in the apical third. Rotary or reciprocating retreatment protocols removed filling material without difference for AH/gutta-percha (G1 and G2: p > 0.05) and BC/CPoint (G3 and G4: p > 0.05). Conclusion: BC/Cpoint is more difficult to be removed from curved root canals than AH/gutta-percha. Reciprocating and rotary instruments have similar ability to remove filling material (AU).

Self-reported habits regarding dental bur use and conditioning among academic and non-academic argentinian dentists / Autoreporte sobre hábitos de uso y acondicionamiento de fresas de odontólogos argentinos en ámbitos académicos y no académicos

ABSTRACT The removal of tissues affected by caries lesions is one of the mostfrequentprocedures in daily dental practice. The aim ofthis study was to collect information about the habits of members of the academic and non-academic dental community in Argentina regarding the use and conditioning of burs employed in the removal of dentin during the treatment of carious lesions. A 14-item questionnaire was prepared, and once validated in small groups, it was sent to three lists of dental subscribers through the computer services area of the School of Dentistry, University of Buenos Aires, Argentina (FOUBA). By the deadline for receiving responses, which was set as four weeks after the sending date, 294 replies were received. Results: percentage (95%CI): 47.93% (42.18-53.68%) of the respondents were faculty members, of whom 37.24% (31.68-42.81%) claimed to belong to FOUBA. Of the respondents, 26.90% (21.79-32.00%) reported being under 35 years old, 37.59% (32.01-43.16%) 36 to 45 years old, 22.07% (17.30-26.84%) 46 to 55 years and 11.38% (7.72-15.03%) over 55 years. Regarding bur type, 68.07% (62.31%-73.44%) claimed to use round burs to remove carious dentin and 27.72% (22.60%-23.31%) round + others. Regarding rotary speed, 22.07% (17.30-26.84%) use medium speed, 32.76% (27.36-38.16%) use high speed, and 32.76% (27.36-38.16%) use medium + super high. Only 17.93% (13.5222.35%) indicated that they know how to quantify the number of times they use their burs, while 50.34% (44.59-56.10%) of the respondents said that they use burs "until they no longer cut", 23.79% (18.89-28.69%) use them 1 to 5 times. 98.27% (96.77-99.77%) said they clean their burs once used. When the answers regarding the use of rubber dam were compared with area of specialization (Chi-square), it was found that faculty members mention the use of burs under rubber dam always or almost always 74.82% (67.60-82.04%) while outside the academic field, 51.01% (42.98-59.03%) of dentists say that they never or almost never do so (p <0.001). Conclusion: Most respondents state that they sterilize their rotary instruments in some way after use. About half of them do not keep track of the number of uses and use burs "until they no longer cut".

RESUMEN La eliminación de los tejidos afectados por las lesiones de caries es uno de los procedimientos más realizados en la práctica diaria de la odontología. El objetivo de este estudio fue recolectar información acerca de los hábitos de miembros de la comunidad odontológica de la Argentina en cuanto a la selección, utilización y acondicionamiento de fresas para la remoción de dentina en el tratamiento de lesiones cariosas. Se elaboró un cuestionario de 14 reactivos que fue validado en pequeños grupos. Una vez definido el formato final se lo envió a tres listas de suscriptores odontólogos a través del de área de Informática de la Facultad de Odontología de la Universidad de Buenos Aires (FOUBA). El plazo para la recepción de respuestas se estableció en cuatro semanas luego del cual se obtuvieron 294 réplicas. Resultados: porcentaje (IC95%), el 47,93% (42,18-53,68%) eran docentes, de los cuales el 37,24% (31,68-42,81%) afirmó ser docente de la UBA. El 26,90% (21,79-32,00%) refirió tener menos de 35 años, el 37,59% (32,01-43,16%) entre 36y 45 años, el 22,07% (17,30-26,84%) entre 46 y 55 años y el 11,38% (7,72-15,03%) más de 55 años. El 68,07% (62,31%-73,44%) afirmó utilizar fresas redondas y el 27,72% (22,60%-23,31%) redondas + otras. En cuanto a la velocidad utilizada: media velocidad: 22,07% (17,30-26,84%), superalta: 32,76% (27,3638,16%), media + superalta: 32,76% (27,36-38,16%). Sólo el 17,93% (13,52-22,35%) indicó que sabe cuantificar la cantidad de usos que les dan a sus fresas, en tanto que el 50,34% (44,5956,10%) de los consultados afirmó que utiliza las fresas "hasta que no corten más", el 23,79% (18,89-28,69%) le da entre 1 y 5 usos. El 98,27% (96,77-99,77%) afirmó que limpia sus fresas una vez utilizadas. Cuando se contrastaron las respuestas respecto al uso de aislamiento con el área de desempeño (Chi-cuadrado) se encontró que los docentes refieren utilizar las fresas con aislamiento absoluto siempre o casi siempre 74,82% (67,60-82,04%) mientras que fuera del ámbito académico el 51,01% (42,98-59,03%) respondieron que nunca ó casi nunca lo hacen (p < 0,001). Conclusión: la mayoría afirma que acondiciona de alguna manera el instrumental rotatorio luego de su uso, alrededor de la mitad no lleva registro del número de usos y sostiene que utiliza las fresas "hasta que no cortan más".

Eficacia de esterilización del instrumental odontológico en las centra-les de esterilización de la Facultad de Odontología de la Universidad Central del Ecuador, mediante la utilización de indicador biológico / Effectiveness of sterilization of dental instruments in the sterilization centers of the Faculty of Dentistry of the Central University of Ecuador, through the use of biological indicator

RESUMEN El riesgo por infección cruzada se encuentra permanentemente durante la práctica odontológica, razón por la cual es vital aplicar las normas de bioseguri-dad y mantener un control estricto del proceso de esterilización del material e instrumental empleado; para esto, la utilización de indicadores biológicos ayu-da a obtener mayor confiabilidad en la determinación de la eficacia del proceso esterilización, ya que evidencian la destrucción o no de esporas. Objetivo: Establecer la eficacia de esterilización por calor húmedo del instrumental odontológico en las centrales de esterilización de pregrado, quirófano y exodoncia de la FOUCE, mediante el uso de indicador biológico en la capacidad máxima de las autoclaves. Materiales y métodos: la investigación fue desarrollada en el autoclave de las centrales de esterilización de pregrado, quirófano y exodoncia FOUCE, colocando un indicador biológico en cada uno de ellos a 121ºC, 1 atmósfera y activando el proceso de esterilización propiamente dicha por 20 minutos, para luego de ser incubado obtener el resultado. Este estudio se llevó a cabo en dos ciclos de esterilización al día, dos días a la semana, durante un mes. Resultados: En la central de esterilización de pregrado, el 100% de sus muestras fueron negativas a presencia de esporas. En la central de esterilización de quirófano el 50% de las muestras fueron negativas y el 50% positivas. Y en la central de esterilización de exodoncia el 94% de las muestras fueron negativas y el 6,0% positivas. Conclusión: La Facultad de odontología de la Universidad Central del Ecuador, en sus centrales de esterilización de pregrado, exodoncia y quirófano cuentan con una eficacia del 81,25%

ABSTRACT The risk of cross infection is permanently found during dental practice; for this reason, it is vital to apply biosafety standards and maintain strict control of the sterilization process of the material and instruments used; for this, the use of biological indicators helps to obtain greater reliability in determining the effectiveness of the sterilization process, since they show the destruction or not of spores. Objective: Establish the effectiveness of wet heat sterilization of dental instruments in FOUCE undergraduate, operating room and exodontic sterilization plants, using the biological indicator in the maximum capacity of the autoclaves. Material and methods: the research was carried out in the autoclave of the FOUCE undergraduate, operating and sterilization plants, placing a biological indicator in each of them at 121°C, 1 atmosphere and activating the sterilization process for 20 minutes, after being incubated get the result. This study was carried out in two sterilization cycles a day, two days a week, for a month. Results: in the undergraduate sterilization center, 100% of its samples were negative in the presence of spores. In the operating room sterilization center 50% of the samples were negative and 50% positive. And in the exodontic sterilization center 94% of the samples were negative and 6.0% positive. Conclusion: The dental faculty of the Central University of Ecuador, in its undergrad-uate sterilization centers, tooth extraction and operating room have an efficiency of 81.25%.

Resistência à fadiga cíclica e torcional dos instrumentos reciprocantes W File e X1 Blue File / Cyclic and torcional fatigue resistance of W File and X1 Blue file reciprocating instruments

Objetivo: O objetivo deste estudo foi avaliar a resistência à fadiga cíclica e torcional dos sistemas reciprocantes WFile 25.07 (WF, TDKaFile, Cidade do México, México) e X1 Blue File 25.06 (X1 BF, MK Life, Porto Alegre, Bra- sil) à temperatura corporal. Material e Métodos: Foram utilizados 40 instrumentos reciprocantes WFile 25.07 (WF 25.07) e X1 BF 25.06 (n=20, cada grupo). O teste de fadiga cíclica foi realizada à temperatura corporal (36±1°C). Os instrumentos foram ativados com movimento reciprocante em um canal artificial de aço inoxidável com ângulo de 60o e 5mm de raio de curvatura (n=10). O teste torcional avaliou o torque e o ângulo de rotação necessários para a fratura dos instrumentos (n=10) nos 3mm iniciais da parte ativa do instrumento, de acordo com a norma ISO 3630-1. Os fragmentos fraturados foram avaliados em microscopia eletrônica de varredura (MEV). Os dados obtidos foram submetidos aos testes estatísticos de Kolmogorov-Smirnov e t de Student, sendo utilizado o nível de significância de 5%. Resultado: O X1BF25.06 apresentou maior tempo e número de ciclos para a fratura do que o WF 25.07 (p<0,05). O teste de torção demonstrou que o WF 25.07 apresentou maior torque do que o X1 BF 25.06 (p<0,05). Em relação ao ângulo de rotação, o X1 BF 25.06 apresentou maiores valores do que o WF 25.07 (p<0,05). Conclusão: O X1 BF apresentou maior resistência à fadiga cíclica e maior ângulo para a fratura do que o WF 25.07. Entretanto, o WF 25.07 apresentou maior torque para a fratura do que o X1 BF 25.06 (AU).

Introduction: The aim of this study was to evaluate the cyclic and torsional fatigue resistance of reciprocating single-file systems W File 25.07 (WF, TDKaFile, Mexico City, Mexico) and X1 Blue File 25.06 (X1 BF, MK Life, Porto Alegre, Brazil) at body temperature. Materials and Methods: Forty reciprocating instruments of the W File 25.07 (WF 25.07) and X1 BF 25.06 (n=20) were used. Cyclic fatigue tests were performed at body temperature (36° ± 1°C). The instruments were reciprocated until fracture occurred in an artificial stainless steel canal with a 600 angle and a 5-mm radius of curvature (n=10). The torsional test evaluated the torque and angle of rotation at failure of new instruments (n=10) in the portion 3 mm from the tip according to ISO 3630-1. The fractured surface of each fragment was observed by using scanning electron microscopy (SEM). Data were analyzed using one-way ANOVA and Tukey tests, and the level of significance was set at 5%. Results: X1 BF 25.06 had significantly higher time and NCF to failure than WF 25.07 (P<0.05). The torsional test showed that WF 25.07 had significantly greater torsional strength (p<0.05). In relation to angular rotation, the X1 BF 25.06 showed higher angular rotation values to failure than WF 25.07 (p<0.05). Conclusion: The X1 BF 25.06 had the highest cyclic fatigue resistance and highest angular rotation values to fracture in comparison with WF 25.07. However, WF 25.07 showed higher torsional resistance to fracture than X1 BF 25.06 (AU).

Influência do ProTaper/ProTaper Next, comparado a outros sistemas rotatórios/reciprocantes, no risco e na intensidade da dor pós-operatória após instrumentação endodôntica em pacientes adultos: uma revisão sistemática e metanálise / Influence of ProTaper/ProTaper Next, compared to other rotatory/reciprocating systems, on the risk and intensity of postoperative pain after endodontic instrumentation in adult patients: a systematic review and meta-analysis

Introdução: O sucesso da terapia endodôntica depende não apenas de sua eficácia e conclusão adequada, mas também do mínimo desconforto do paciente. Objetivo: O objetivo dessa revisão sistemática e metanálise é avaliar o risco e a intensidade da dor endodôntica pós-instrumentação em pacientes adultos. Métodos: Uma pesquisa abrangente foi realizada no MEDLINE via PubMed, Scopus, Web of Science, LILACS, BBO e Cochrane Library e SIGLE, sem restrições. Também foram pesquisadas a conferência anual dos resumos da IADR (1990-2016) e o registro de ensaios não publicados e em andamento. As dissertações e teses foram pesquisadas utilizando-se os bancos de dados das dissertações ProQuest e das bases de teses Periódicos Capes. Apenas ensaios clínicos randomizados que compararam o risco ou a intensidade da dor resultante do tratamento endodôntico em pacientes adultos foram incluídos. Resultados: Após a remoção das duplicatas, 827 artigos foram identificados. Após a triagem do título e resumo, restaram 26 estudos, dos quais 13 foram ainda excluídos, permanecendo 10 para análise qualitativa e 7 para a metanálise. Não foi observada diferença significativa no risco/ intensidade da dor após o tratamento endodôntico nesse estudo. O risco de dor foi de 1,09, com intervalo de confiança de 95%, variando de 0,87 a 1,38 (p=0,45). A diferença padronizada g de Hedges nas médias da intensidade da dor após 24 horas foi de ­ 0,05, com intervalo de confiança variando de ­ 0,21 a 0,11 (p=0,53). Conclusões: Nessa metanálise, não foram encontradas diferenças no risco e na intensidade da dor após o tratamento endodôntico com ProTaper e outros sistemas rotatórios ou reciprocantes (AU).

Introduction: The success of endodontic therapy depends not merely on their efficacy and proper completion but also on minimal patient discomfort. The purpose of this systematic review and meta-analysis is to evaluate the risk and intensity of post instrumentation endodontic pain in adult patients. Methods: A comprehensive search was performed in the MEDLINE via PubMed, Scopus, Web of Science, LILACS, BBO and Cochrane Library and SIGLE without restrictions. The annual conference of the IADR abstracts (1990-2016), and unpublished and ongoing trials registry were also searched. Dissertations and theses were searched using the ProQuest Dissertations and the Periodicos Capes Theses Databases. Only randomized clinical trials that compared the risk or intensity of pain resulting from endodontic treatment in adult patients were included. Results: After the removal of duplicates, 827 articles were identified. After title and abstract screening, 26 studies remained. Thirteen studies were further excluded while 10 studies remained for qualitative analyses and 7 for the meta-analysis. No significant difference in the risk/intensity of pain after endodontic treatment was observed in this study. The risk of pain ratio was 1.09, with a 95% confidence interval of 0.87 to 1.38 (p = 0.45). The Hedges g standardized difference in means of pain intensity at 24 h was -0.05, with a confidence interval varying from -0.21 to 0.11 (p = 0.53). Conclusions: No differences in risk and intensity of pain after endodontic treatment with ProTaper and other rotatory or reciprocating systems were found in this meta-analysis (AU).