Comparación entre los sistemas manual de limas de acero inoxidable y el rotatorio de limas de níquel titanio, en la conformación de conductos radiculares curvos in vitro / Comparison between the manual system of stainless steel files and the rotating system of nickel titanium files in the conformation of curved radicular ducts in vitro

Resumen Introducción: Estudio experimental donde se procuró comparar el efecto del sistema manual y del rotatorio sobre la conformación de conductos curvos. Metodología: Una muestra de 40 raíces mesiales de primeras molares inferiores fue aleatorizada en dos grupos iguales: grupos sistema manual de limas K y sistema rotatorio FGK Race®. Se comparó el radio de la curvatura final vs. el inicial mediante el programa Autocat 2015. Se empleó la prueba t con significancia de 0,05. Resultados: El radio de la curvatura varió de manera significativa, tanto para sistema manual como para el rotatorio FGK Race® (p=0,0001 y p=0,0013, respectivamente). Además, el sistema manual produjo mayor variación en el radio de la curvatura al compararlo con el sistema rotatorio 2,23 mm vs. 1,27 mm respectivamente; p=0,13. Conclusiones: Ambos sistemas produjeron modificación en la conformación de los conductos mesiales; sin embargo, en la comparación entre ambos dichas diferencias no fueron significativas.

Abstract Introduction: An experimental study was carried out to compare the effect of the manual system and the rotary system on the conformation of curved conduits. Methodology: A sample of 40 mesial roots of lower first molars was randomized into two equal groups: group manual system of K-files and group rotary system FGK Race®. The radius of the final curvature vs. the initial curvature was compared using the Autocat 2015 program. The t-test with a significance of 0.05 was used. Results: The curvature radius varied significantly for both the manual system and the rotary FGK Race® (p = 0.0001 and p = 0.0013, respectively). In addition, the manual system produced greater variation in the radius of the curvature when compared to the rotary system 2.23mm vs. 1.27mm respectively; p = 0.13. Conclusion: Both systems produced modification on the conformation of the conduits of the mesial roots; however, in the comparison between both systems said differences were not significant.

The comparison of the rate of apical displacement in curved root canals using Neoniti and RaCe files by cone beam CT Scan / Comparação da taxa de desvio apical em canais radiculares curvos utilizando limas Neoniti e RaCe por meio de tomografia computadorizada cone beam (TCCB)

Objective: There is a high prevalence of root canal transportation in the teeth with the curve. Effect of root canal transportation on the success of root canal therapy of tooth is negative and there is no study about comparing RaCe and Neoniti files in root canal transportation. The aim of this study is assessment and comparing two different RaCe and Neoniti files to determine transportation error in various parts of root using CBCT assessment and comparing them with each other. Material and Methods: In this experimental study 50 extracted mandibular molar teeth selected. Teeth were divided randomly into two groups i.e. 25 teeth threated with RaCe file (first group) and 25 teeth threated with Neonitu files (second group). CBCT images were used to measurement thickness of dentine, before and after instrumentation that obtain from NNT viewer 6.1.0 software. Results: In the first group, the mean tooth transportation in 5 mm of apex was 0.15 and, in the second group, the mean tooth transportation in 5 mm of apex was 0.18 mm. There was no statistically significant difference in canal transportation between RaCe and Neoniti files in five millimeters distant from apex area (p = 0.492) and the mean transportation from 9 mm of apex were 0.14 in the second group. There was no statistically significant difference in canal transportation between two groups (p = 0.911). Conclusion: In comparison of these two rotary files, both are equally safe regarding the extent of apical transportation. (AU)

Objetivo: Existe uma alta prevalência de desvio apical em canais radiculares curvos. O efeito do desvio apical no canal radicular sobre o sucesso da terapia endodôntica é desfvorável e não há nenhum estudo comparando as limas RaCe e Neoniti em relação ao desvio apical dos canais radiculares durante o preparo. O objetivo deste estudo é avaliar e comparar duas diferentes limas, RaCe e Neoniti, a fim de para determinar o erro de desvio em várias porções radiculares através de análise por TCCB e compará-los entre eles. Material e Métodos: Neste estudo experimental, 50 dentes molares mandibulares extraídos foram selecionados. Os dentes foram divididos aleatoriamente em dois grupos, ou seja, 25 dentes preparados com as limas RaCe (primeiro grupo) e 25 dentes preparados com limas Neoniti (segundo grupo). Neste estudo para medir a espessura da dentina através do escaneamento, antes e depois da instrumentação, ao mesmo tempo, usamos imagens axiais obtidas do software NNT viewer 6.1.0. Resultados: No primeiro grupo, o desvio apical médio a 5 mm do ápice foi de 0,15 e no segundo grupo o desvio apical médio a 5 mm do ápice foi de 0,18 mm, não havendo diferença estatisticamente significante entre as limas RaCe e Neoniti a cinco milímetros da porção apical (p = 0,492) e o transporte médio a 9 mm do ápice foi de 0,14 no segundo grupo não havendo diferença estatisticamente significante no desvio apical entre os dois grupos (p = 0,911). Conclusão: Os resultados indicaram que não houve diferença significativa no desvio apical médio entre dois sistemas de limas em 3, 9, 7, 5 e 11 mm do ápice e ambos as limas foram seguras (AU)

In Vitro Study of Four Endodontic Irrigation Protocols on Smear Layer Removal in Curved Canals / 天津医药

Objective To investigate the effective endodontic irrigation protocols on smear layer removal from curved canals. Methods Forty extracted mandibular first molars with curved mesial root canal were selected and decoronat-ed. Mesiobuccal root canal was instrumented to F3 using handed ProTaper system, and randomly divided into four groups ac-cording to final irrigation protocols: syringe irrigation (group A), #30K file agitation (group B), passive ultrasonic irrigation (PUI, group C) and combination of #30K file agitation and PUI (group D). The ultrasonic file was located within 0.5 mm coro-nal from start of the curvature. All root canals were mesio-distally split, snicked at the start of the curvature and 2 mm apical-ly from the start of the curvature, and divided into three sections. They wereⅠ,ⅡandⅢfrom coronal to apical. The smear layer of each section of root canal was examined under scanning electron microscope (SEM). Results Group D presented small amounts of scattered or thin smear layers and obtained the lowest score at each section of root canal wall. At sectionⅠandⅡ, there was no significant difference in smear layer score between group D and group C. The smear layer scores were both significantly lower in group D and group C than those of group A and group B (P<0.05). At sectionⅢ, the smear layer score was significantly lower in group D than that of group A, group B and group C, and which was significantly lower in group B and group C than that of group A (P<0.05). Conclusion When ultrasonic file was located coronal from the start of the curvature, K file, which was the same size as dimension of apical portion preparation to agitate and PUI can remove smear layer from curved canals efficiently.

Geometric and dimensional characteristics of simulated curved canals prepared with proTaper instruments

OBJECTIVE: This study identified which regions of ProTaper instruments work during curved root canal instrumentation. MATERIAL AND METHODS: Twelve ProTaper instruments of each type, S1, S2, F1, and F2, were assessed morphometrically by measuring tip angle, tip length, tip diameter, length of each pitch along the cutting blades, and instrument diameter at each millimeter from the tip. Curved canals in resin blocks were explored with manual stainless steel files and prepared with ProTaper instruments until the apical end following four distinct sequences of instrumentation: S1; S1 and S2; S1, S2, and F1; S1, S2, F1, and F2. Image analysis was employed for measuring canal diameters. The diameters of the canals and diameters of the instruments were compared. Data were analyzed by one-way ANOVA and Tukey's test. RESULTS: No statistically significant difference was found between the canals and instrument diameters (p>0.05). The largest diameters in the end-point of the instrumented canals were obtained with F1 and F2 instruments and in the initial and middle thirds with S1 and S2 instruments. CONCLUSIONS: All instruments worked at the tip and along their cutting blades, being susceptible to fail by torsion, fatigue, or the combination of these two mechanisms.

Efeitos do preparo cervical com brocas Gates-Glidden e LA Axxess no desvio apical após preparo biomecânico de canais radiculares / Effects of coronal flaring using Gates-Glidden and LA Axxess burs on apical deviation after root canals biomechanical preparation

Este trabalho teve por objetivo comparar a influência do desgaste cervical realizado com as bricas Gates-Glidden e LA Axxess sobre a ocorrência de desvio apical após o preparo biomecânico dos canais radiculares. Foram selecionados trinta canais mesiovestibulares de molares inferiores humanos do Banco de Dentes da Faculdade de Odontologia da Universidade de Passo Fundo. Os dentes foram acessados e, com auxílio de uma plataforma posicionada, foi realizada uma tomada radiográfica inicial com uma lima # 10 no comprimento real de trabalho. As películas radiográficas utilizadas não foram reveladas a fim de permitir uma segunda exposição. Os dentes foram divididos aleatoriamente em dosi grupos (n =15): Grupo 1 - preparo cervical com brocas Gattes-Glidden; Grupo 2 - preparo cervical com brocas LA Axxes. Posteriormente, os canais foram instrumentados até a lima # 30 no comprimento real de trabalho. Uma nova tomada radiográfica foi realizada pela técnica da dupla exposição sobre plataforma posicionadora. As películas radiográficas foram reveladas e, após, avaliadas por três examinadores. Os dados foram submetidos ao Teste U de Mann-Whitney, que demonstrou não haver diferença estatística significativa entre os dois grupos (p>0,05). Nas condições experimentaisfoi possível concluir que os preparos cervicais realizados com as brocas Gates-Glidden e LA Axxess mostraram níveis semelhantes de ocorrência de desvio apical.

Shaping effects of multi-taper nickel-titanium files combined with nickel-titanium K file in simulated S-shaped canals / 实用口腔医学杂志

Objective:To evaluate the shaping effects of multi-taper ProTaper combined with nickel-titanium(Ni-Ti) K file in simulated S-shaped canals. Methods:Thirty simulated S-shaped resinous canals were randomly divided into three groups and prepared with hand ProTaper, hand Ni-Ti K file, hand ProTaper combined with Ni-Ti K file respectively. The shaping effects were assessed by the amount of material removed from the inner and outer wall of canal as well as the width of canal after instrumentation. Results: The shaping files of ProTaper removed the least material in amount of materials from the same apical dimension. The finishing files of ProTaper removed the most amount of material at the inner side of curvature and outer side of apex. ProTaper combined with Ni-Ti K file removed the least material at the above parts and the widths of canals prepared were gradually decreased from the orifice to the apex. Conclusion:ProTaper combined with Ni-Ti K file exhibited good shaping effects in simulated S-shaped canals.