Impact of cooling on shaping ability of thermally treated files in canal models with double curvature.

Background: This study compared the ability of thermally treated files in shaping simulated canals with double curvature. Fifty-six canals were enlarged to a final size of 25 with ProTaper Next (PTN) or ZenFlex (ZF). Materials: Half of the samples were shaped with cooled files (n = 14 each). The amount of removed resin was measured and canal deviation was determined at eight levels. Shaping time and maximum shaping torque values were also recorded. Data were statistically analyzed using analysis of variance and LSD, Kruskal-Wallis, and chi-square tests at a 0.05 significance level. Results: Compared to PTN and cooled PTN, ZF and cooled ZF required lesser time to shape the canals. The maximum torques were found comparable between the groups. All the groups generated negligible deviations at every canal level evaluated and maintained the canal geometry. Although not significant, the cooled PTN and ZF files exhibited lesser canal deviations than their counterparts. Conclusion: All groups demonstrated similar shaping ability whilst maintaining the original curvature of the canal in simulated canals with double curvature. However, ZF groups were able to shape the canals faster than PTN groups. There was a trend that cooled files made lesser canal deviations compared to their counterparts.

BlueShaper: un nuevo sistema multialeación para la instrumentación mecanizada en endodoncia: comunicación breve / BlueShaper: a new multialloy system for mechanized instrumentation in endodontics: brief communication

El objetivo de esta comunicación es describir y analizar el sistema BlueShaper para la preparación quirúrgica mecaniza- da de los conductos radiculares. El sistema dispone de un set básico de 4 limas: Z1, Z2, Z3 y Z4, con un D0 de 0,14 mm, 0,17 mm, 0,19 mm y 0,25 mm respectivamente y conicidad variable que oscila entre el 2 y 10 %. La lima Z1 posee una aleación Pink, que le confiere mayor resistencia a la torsión y una gran capacidad de corte. Las limas Z2, Z3 y Z4 presentan una aleación Blue que aumenta la resistencia a la fatiga cíclica e incrementa su flexibilidad. Para conductos radiculares más amplios se incluyen, además, las limas Z5, Z6 y Z7. La empresa comer- cializa conos de gutapercha BlueShaper que se corresponden con las limas Z3, Z4, Z5, Z6 y Z7. El sistema de limas mul- tialeación Blue Shaper podría considerarse como un nuevo aporte clínico para la preparación mecánica de los conductos radiculares (AU)

The aim of this communication was to describe and analyze the BlueShaper system for the mechanized surgical preparation of root canals. The system has a basic set of 4 files: Z1, Z2, Z3 and Z4, with 0.14 mm, 0.17 mm, 0.19 mm and 0.25 mm DO respective- ly, and variable conicity ranging between 2 and 10 %. Z1 file has a Pink alloy, which gives it greater resistance to torsion and great cutting capacity. The Z2, Z3 and Z4 files feature a Blue alloy that increases resistance to cyclic fatigue and increases their flexibility. For larger root canals, the Z5, Z6 and Z7 files are also included. The company supplies specific BlueShaper ́s gutta-percha cones for Z3, Z4, Z5, Z6 and Z7 files. The BlueShaper multialloy file system could be consid- ered as a new clinical contribution for the mechanical prepa- ration of root canals (AU)

Adjunctive use of different lasers Er, Cr: YSGG, femtosecond, potassium titanyl phosphate and photodynamic therapy on radicular disinfection bonded to glass fiber post.

OBJECTIVE: The aim of this study was to evaluate and compare the effect of different laser prototypes [Er, Cr: YSGG laser (ECYL), potassium titanyl phosphate laser (KTP), and Femtosecond laser (FSL)]and curcumin photosensitizer (CP) activated by Photodynamic therapy (PDT) on the bond strength of Pre-fabricated fiber reinforced composite (PFRC) post-bonded to radicular dentin. MATERIALS AND METHODS: A total of fifty mandibular single-rooted closed apex teeth were extracted carefully, assembled, and decoronated up to the cementoenamel junction. The working length of all specimens was determined by using a 10 K patency file and later, were cleaned and shaped with Protaper NiTi system using the crown down approach, dried, and obturated with gutta-percha using an AH Plus sealer. Post space was prepared by guiding peeso-reamer. Based on the method of disinfection, the samples were allocated to five groups (n=10) at random: samples in group 1: curcumin photosensitizer (CP) activated by PDT, samples in group 2 disinfected using 5.25% NaOCl+17% EDTA, samples in group 3 disinfected using 5.25% NaOCl+17% EDTA+FSL, specimens in group 4 sterilized using 5.25% NaOCl+17% EDTA+KTP and samples in group 5 cleaned with 5.25% NaOCl+17% EDTA+ECYL. The fiber post was cemented via self-etch resin cement into the post space. All specimens with posts were dissected perpendicularly into apical, middle, and coronal dentin and subjected to the universal testing machine for push-out bond strength (PBS) testing. Statistical analysis was performed using a One-Way analysis of variance and Post Hoc Tukey multiple comparison tests. RESULTS: The highest PBS was corroborated when the radicular canal was disinfected with 5.25% NaOCl +17% EDTA+ ECYL at all three root levels (coronal, middle, and apical) and the lowest was adjudicated by decontamination with CP activated by PDT at all inspected root levels. Intergroup comparison presented that specimens in group 2: 5.25% NaOCl+17% EDTA (control) and group 4: 5.25% NaOCl+17% EDTA+KTP revealed comparable PBS outcome to group 5 (p>0.05) while samples in group 3 revealed the equivalent PBS values to group 1 (p<0.05) at all three root levels. CONCLUSIONS: Er, Cr: YSGG laser and potassium titanyl phosphate laser when used in combination with the conventional canal disinfection 5.25% NaOCl and 17% EDTA demonstrated the highest push-out bond strength values at coronal, middle, and apical levels of the root.

Shaping ability of non-adaptive and adaptive core nickel-titanium single-file systems with supplementary file in ribbon-shaped canals analysed by micro-computed tomography.

This study compared shaping ability between two single-file systems and before/after using supplementary file in untouched area, volume of removed dentin, maximum cut depth (the highest cut depth by main file) and remaining thinnest dentin (the thinnest root dentin after preparation). Ribbon-shaped distal canals of mandibular molars were prepared with non-adaptive core (WaveOne Gold) or adaptive core (XP-endo Shaper) files (n = 15/group) and additionally prepared with a supplementary file (XP-endo Finisher), and the shaping ability was investigated using micro-computed tomography. XP-endo Shaper group demonstrated significantly less overall untouched area than WaveOne Gold group (38.21 ± 6.98% vs. 47.68 ± 9.16%) (p < 0.05). No significant difference was detected between XP-endo Shaper and WaveOne Gold groups in volume of removed dentin (1.85 ± 0.53 vs. 1.66 ± 0.33 mm3 ), maximum cut depth (0.10-0.28 vs. 0.10-0.29 mm) and remaining thinnest dentin (0.66-0.80 vs. 0.78-0.88 mm). Supplementary XP-endo Finisher treatment significantly decreased untouched area (11%-23% reduction) (p < 0.05) with minimally cut root dentin (0.01-0.02 mm).

Effect of Glycolic Acid, Maleic Acid, and EDTA in the Removal of Smear Layer from Root Canal Dentin

ABSTRACT Objective: To assess the efficacy of 5% Glycolic Acid (GA), 17% ethylenediaminetetraacetic acid (EDTA) and 7% maleic acid (MA), in removing the smear layer (SL). Material and Methods: For the experiment, forty single-rooted human teeth were selected. To perform the chemo‑mechanical preparation, the root canals were instrumented to an apical size of #30, along with simultaneous irrigation of 2.5% NaOCl. The samples were allotted to the experimental groups based on the final irrigating solution (n=10): (1) The GA group: 05%, (2) the EDTA group: 17%, (3) the MA group: 7%, and (4) the control group: Distilled water. The teeth were evaluated for the presence or absence of SL using SEM. Results: Comparing the 5% GA, 7% MA and 17% EDTA groups, no statistically significant differences were found at the coronal and middle thirds (p>0.05). However, in the apical third, MA had greater efficacy than EDTA (p=0.002) and GA (p=0.041), with a significant difference in the SL removal, while there was no significant difference between the latter (p=0.148). Conclusion: Thus, it was concluded that 7% maleic acid as a final irrigating solution is more efficacious than 17% EDTA and 5% glycolic acid in eliminating the smear layer from the apical portion of the root canal.

Endodontic file separation and its management among dentists in Punjab, Pakistan: a cross-sectional study

The study aimed to find the incidence and awareness of endodontic instrument separation and its management among dental house officers, postgraduate trainees, demonstrators, consultants, and general dentists. Methods: This online questionnaire-based cross-sectional study was conducted with the approval of the IRB in private and public dental hospitals and dental clinics in Punjab. The authors developed the survey tool, which comprises 24 closed-ended items regarding demographics, the incidence of file separation, and awareness about its management. The data were analyzed using IBM SPSS version 24. The Chi-Square Test was used to compare percentages of categorical variables. Results: Postgraduate trainees experienced the most instrument separations (43.6%), made the most retrieval attempts (49.2%), and experienced the most secondary errors during retrieval (52.1%) (p<0.001). Around four out of ten respondents always informed the patients (39.6%) and department (41.6%) about errors. Manual files (69.8%), stainless steel files (75.8%), and short files (60.4%) were more frequently separated, and the most frequent cause was older fatigue files (57.7%). Manual files were more frequently broken in public dental institutes (p=0.003). Two-thirds of the file separations (72.5%) occurred during cleaning and shaping in the apical third of molars (65.1%), especially in mesiolingual canal (56.4%). Bypass attempt was the most common in symptomatic teeth (47.7%). Conclusions: Preventive approaches such as limiting file reuse and constructing a glide path can reduce the occurrence of file separation. Operators should be familiar with the number of uses of the instrument before fatigue and should be trained through workshops and refresher courses

Comparison of five single-file systems in the preparation of severely curved root canals: an ex vivo study.

BACKGROUND: The ex vivo study is to compare the root canal preparation outcomes achieved by five nickel-titanium single-file instrumentation systems (M3-L, Reciproc Blue, V-Taper 2H, WaveOne Gold, XP-endo Shaper) in severely curved molar root canals. METHODS: A total of 60 root canals were selected from extracted human molar teeth with curvatures ranging from 25° to 50° and divided into five groups based on the instrumentation system employed (n = 12). Before and after root canal preparation, a Micro-CT scan was taken, and pre- and post-operative data were analyzed to evaluate the following parameters: volume increment of root canals (VI), untouched root canal areas (UTA), and canal transportation (CT). Apically extruded debris (AD) was collected during preparation. After that, all samples were separated into two parts and examined respectively by scanning electron microscope (SEM) to assess cleaning ability. Data were statistically analyzed with ANOVA (UTA, AD, VI) or Kruskal-Wallis test (CT, SEM-score), the level of significance was set at α = 0.05. RESULTS: There were no significant differences between the five systems regarding the AD, VI, and UTA parameters (P > 0.05). In terms of CT, no significant difference was noted at the straight section of canal and apical levels, while XP-endo Shaper showed less canal transportation than M3-L at the level of curved vertex (P < 0.05), and the centering ability of V-Taper 2H was significantly better than WaveOne Gold at the initial point of bending (P < 0.05). Debris and smear layers were present on the canal walls of all specimens, the apical thirds of the canal presented higher SEM scores than the coronal thirds in all groups (P < 0.05). Reciproc Blue and XP-endo Shaper showed fewer smear scores than WaveOne Gold in the apical thirds (P < 0.01 and P < 0.05, respectively), and no statistical difference was found between other groups in the middle and coronal thirds. CONCLUSION: The five single-file systems evaluated performed equally in apically debris extrusion, dentin removal, and untouched root canal areas, while XP-endo Shaper and V-Taper 2H resulted in less canal transportation compared to M3-L and WaveOne Gold. Regarding cleaning ability, Reciproc Blue and XP-endo Shaper were associated with less smear layer than WaveOne Gold in the apical thirds.

Comparative Evaluation of Root Canal Centering Ability of ProTaper, Mtwo, WaveOne, and Reciproc Using Cone-beam Computed Tomography: In Vitro Study.

AIM: To compare the centering ability of rotating (ProTaper and Mtwo) and reciprocating (WaveOne and Reciproc) file systems using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Eighty extracted human mandibular molars with curvature within 15-45° were selected and randomly divided into four groups (n = 20): group I (ProTaper), group II (Mtwo), group III (WaveOne), and group IV (Reciproc). The selected teeth were arranged in a template, and pre-instrumentation and post-instrumentation CBCT scans were taken using Kodak Carestream CS 9300 machine. The centering ability was measured in four planes namely, at furcation, 3 mm apical to furcation (coronal), 6 mm apical to furcation (middle), and 3 mm coronal to the apex (apical), wherein dentin thickness was measured from pre- and post-instrumentation CBCT scans and recorded for each canal (mesiobuccal and mesiolingual) separately and statistically analyzed. RESULTS: Mtwo and Reciproc remained better centered followed by WaveOne and least by ProTaper in different-level comparisons. In the mesiodistal dimension (MD) at the 3 mm, 6 mm, and 3 mm apical level, Mtwo and Reciproc showed better centering, meanwhile, in the buccolingual dimension, only in the 3 mm apical level, Mtwo and Reciproc remain better centered. A significant difference was seen between the group and type of canal. CONCLUSION: Mtwo and Reciproc showed better centered preparation than ProTaper and WaveOne. Significant differences were seen between the groups and types of canal. CLINICAL SIGNIFICANCE: Root canal instrumentation should maintain the original canal anatomy. The proper enlargement keeping in mind the remaining strength in the tooth structure is essentially decided by how the selected instrument is centered. The alloy used for instrument manufacture and its design (taper, cross-section, and tip) will influence the centered preparation. The type of instrument and the instrumentation techniques should be chosen based on root canal anatomy.

Percepção de uso e preparo químico mecânico realizado com diferentes instrumentos endodônticos por estudantes de graduação em Odontologia: uma revisão sistemática de estudos laboratoriais / Undergraduate dental students' use perception of different endodontic instruments for mechanical­chemical preparation: a systematic review of laboratory studies

O estudo revisou a literatura existente com o objetivo de comparar a percepção de uso, qualidade e tempo do preparo químico mecânico de canais radiculares realizado por estudantes de graduação em Odontologia com instrumentos de níquel-titânio (NiTi) e aço inoxidável. Para isso, as bases de dados eletrônicas PubMed, LILACS, Scopus, Embase,SciELOe CENTRALforam acessadas para verificar e selecionar estudos relacionados com a questão de pesquisa publicados até janeiro de 2021. Estudos laboratoriaisque compararam o uso de instrumentos de NiTi com aço inoxidável por alunos de graduação em Odontologia foram avaliados. Dois revisores independentemente selecionaram os estudos, coletaram os dados e analisaram o risco de viés.Dos 92 estudos potencialmente relevantes, 10 atenderam aos critérios de inclusão para análise de texto completo e, posteriormente, incluídos na revisão sistemática. O risco de viés foi considerado alto em todos os estudos. Instrumentos de NiTi apresentarammaior preferência e melhor percepção por estudantes de graduação em Odontologia, menor tempo e melhor qualidade do preparo químico mecânico, commenor ocorrência de acidentes como degraus, transporte e desvios de canal, apesar de estarem associados à maior ocorrência de fratura de instrumentos (AU).

This literature review aimed to compare undergraduate dental students' perceptions regarding the use of nickel­titanium (NiTi) and stainless steel instruments for the mechanical-chemical preparation of root canals, focusing on quality and time. PubMed, LILACS, Scopus, Embase, SciELO,and CENTRAL electronic databaseswere accessed to verify and select related studies published as of January 2021. Laboratory studies comparing the use of NiTi instruments with stainless steel instruments by undergraduate dental students were evaluated. Two reviewers independently selected the studies, collected the data, and analyzed the risk of bias. Out of the 92 potentially relevant studies, 10 met the inclusion criteria for a full-text analysis and were subsequently included in the systematic review. The risk of bias was considered high in all studies. Undergraduate dental students demonstrated a greater preference for and better perception of NiTi instruments. NiTi instruments also resulted in less time for and better qualityof the mechanical-chemical preparation. These were associated with a lower incidence of accidents, such as canal ledges, transportations, and deviations, as well as a higher incidence of instrument fractures (AU).

Alargamento do forame como complemento no tratamento endodôntico para regeneração de uma lesão periapical extensa: relato de caso / Foraminal enlargement as a complement in the endodontic treatment for the regeneration of an extensive periapical lesion. A case report

Introdução: O alargamento do forame refere-se ao alargamento mecânico intencional do forame para reduzir a carga bacteriana em uma área afetada frequentemente por infecções endodônticas além do limite da constrição apical. Objetivo: O objetivo do presente relato de caso é apresentar a técnica de alargamento do forame de um dente com lesão periapical extensa, como complemento do tratamento endodôntico e alternativa precoce à microcirurgia periapical. Métodos: É apresentado o caso de um incisivo lateral superior endodonticamente tratado, com uma extensa lesão periapical associada. Devido à história clínica e radiográfica, tempo decorrido desde o tratamento endodôntico inicial e alta probabilidade de áreas de reabsorção apical com biofilme extrarradicular, o retratamento endodôntico com alargamento do forame foi indicado como primeira opção, adiando a indicação de cirurgia endodôntica de acordo com a evolução. Resultados: Na avaliação de acompanhamento de dois anos, por exame de imagem, observou-se evolução clínica favorável ao retratamento, com aumento total da densidade óssea. O procedimento cirúrgico endodôntico complementar foi descartado. Conclusão: O alargamento do forame é uma alternativa complementar viável em casos de periodontite apical de longa duração com suspeita de biofilme no nível do forame. Pode ser considerado uma opção antes da indicação de retratamento endodôntico cirúrgico (AU).

Introduction: Foraminal enlargement refers to intentional mechanical enlargement of the foramen to reduce the bacterial load in an area frequently affected by endodontic infections beyond the limits of the apical constriction. The objective of this case report is to present the foraminal enlargement technique of a tooth with an extensive periapical lesion as a complement in the endodontic treatment and an early alternative to periapical microsurgery. Materials and methods: The case is presented of an endodontically treated upper lateral incisor with an extensive associated periapical lesion. Due to the clinical and radiographic history, the time elapsed since the initial endodontic treatment, and the high probability of areas of apical resorption with extra-radicular biofilm, endodontic retreatment with foraminal enlargement was indicated as the first option, postponing the indication for endodontic surgery according to evolution. Results: In the follow-up appointment at 2 years, a favorable clinical imaging evolution of retreatment was observed, with a total increase in bone density. The complementary endodontic surgical procedure was discarded. Conclusion: Foraminal enlargement is a viable complementary alternative in cases of long-term apical periodontitis with suspicion of biofilm at the foramen level. It can be considered an option before the indication of surgical endodontic retreatment (AU).

Introduction of nickel titanium rotary instruments to undergraduate students: afour-yearclinical experience / Introdução de instrumentos rotários de níquel titânio para alunos de graduação: quatro anos de experiência clínica

Many studies address the quality of root canal treatments, but few refer to endodontics usingrotatory techniques performed by noviceoperators. This study evaluatedthe performance of undergraduates in their first contact with rotary root canal instrumentation concerningthe findings of the final periapical radiograph, and thepostendodontic treatment pain.A longitudinal observational studywas performed on periapical radiographs of 491teethfrom 450 patientssubmitted toroot canal treatmentby undergraduate students from 2015 to 2018. The analysis of the length of root canal filling followed the criteria: (i) acceptable, ifperiapical radiograph presentsroot filling ending 0 -1 mm short of radiographic apex; (ii) over, if periapical radiograph presentsroot filling ending beyond the radiographic apex; and (iii) under, ifperiapical radiograph presentsroot filling ending > 1 mm short of radiographic apex. Evaluation of postendodontic treatment painwas categorized into either absence or presenceof pain. Adequate length root canal filling was observed in 65.9% of the cases (324 teeth). Periapical lesions presenceand dimensions did not interfere to the obturation quality.Statistical relation was found between the pulp condition and postendodontic treatment pain. Thepresence of pain was observed in 4.7% of the vital teeth and 0.3% of non-vital teeth. The presence of periapical lesion did not influence postoperative pain.AdequatelengthrootcanalfillingwasobservedinmostcasesandNitTi rotary instrumentation hadapplicability in undergraduate programs, even with novice operators. Besides that, pulp condition had an effect on post endodontic pain (AU).

Muitos estudos abordam a qualidade dos tratamentos de canal radicular, mas poucos se referem à endodontia por meio de técnicas rotatórias realizada por operadores novatos. Este estudo avaliou o desempenho de graduandos no primeiro contato com a instrumentação endodôntica em relação aos achados da radiografia periapical final e à dor pós-tratamento endodôntico. Um estudo observacional longitudinal foi realizado em radiografias periapicais de 491 dentes de 450pacientes submetidos a tratamento endodôntico por estudantes de graduação no período de 2015 a 2018. A análise do comprimento da obturação de canais radiculares obedeceu aos critérios: (i) aceitável, se a radiografia periapical apresentasse término de obturação 0 -1 mm aquém do ápice radiográfico; (ii) acima, se a radiografia periapical apresentasse obturação que termina além do ápice radiográfico; e (iii) abaixo, se a radiografia periapicalapresentasse obturação, terminando > 1 mm aquém do ápice radiográfico. A avaliação da dor pós-operatória foi categorizada em ausência ou presença de dor. A obturação de canais radiculares de comprimento adequado foi observada em 65,9% dos casos (324 dentes). A presença e as dimensões das lesões periapicais não interferiram na qualidade da obturação. Foi encontrada relação estatística entre a condição pulpar e a dor pós-tratamento endodôntico. Presença de dor foi observada em 4,7% dos dentes vitais e 0,3% dos não vitais. A presença de lesão periapical não influenciou na dor pós-operatória. O comprimento de trabalho adequado foi observado na maioria dos casos e a instrumentação rotatória NitTi teve aplicabilidade em programas de graduação, mesmo com operadores iniciantes. Além disso, a condição pulpar afetou a dor pós-operatória (AU).

Influência do pré-alargamento coronário na resistência à fadiga cíclica de instrumentos reciprocantes tratados termicamente / Influence of coronal pre-enlargement on cyclic fatigue resistance of heat-treated reciprocating instruments

Objetivo: O objetivo do presente estudo foi avaliar a influência do pré-alargamento coronário na resistência à fadiga cíclica de dois instrumentos reciprocantes tratados termicamente. Métodos: 20 instrumentos Reciproc Blue (R25 Blue) e 20 instrumentos X1 Blue (X1) foram utilizados para instrumentar blocos de resina simulando um molar superior com três canais radiculares. Os dentes foram divididos em quatro grupos (n=10), de acordo com o instrumento e com a técnica de instrumentação utilizada: grupos R25 e X1 - instrumentação com R25 Blue (25/0.08) ou X1 Blue (25/0.06), respectivamente, sem alargamento prévio; e grupos R25 ou X1 + pré-alargamento cervical - pré-alargamento com os instrumentos ProTaper Universal SX e S1 antes da instrumentação com R25 Blue ou X1. Os instrumentos foram testados com relação à fadiga cíclica utilizando-se um canal simulado de aço inoxidável com ângulo de curvatura de 86 graus e raio de curvatura de 6 mm. Os instrumentos foram acionados utilizando-se o movimento "RECIPROC ALL" do motor endodôntico (VDW) e o tempo de instrumentação até a fratura do instrumento foi contabilizado. Os resultados foram analisados pelo teste t de Student (p<0,05). Resultados: Os instrumentos X1 apresentaram maior resistência à fadiga cíclica do que R25 Blue em ambas as condições testadas (p<0,05). Não houve diferença entre os grupos com e sem pré-alargamento coronário para os instrumentos R25 Blue e X1 (p>0,05). Conclusão: O instrumento X1 Blue apresentou maior resistência à fadiga cíclica do que o Reciproc Blue. O pré-alargamento coronário não foi capaz de aumentar a resistência à fratura por fadiga cíclica dos instrumentos testados (AU).

Objective: The aim of this study was to evaluate the influence of cervical pre-flaring on the cyclic fatigue resistance of two heat-treated reciprocating instruments. Methods: 20 Reciproc Blue (R25 Blue) instruments e 20 X1 Blue File (X1) were used to instrument resin blocks simulating an upper molar with 3 root canals. The specimens were divided into four groups (n=10) according the instrument and type of instrumentation used: R25 and X1 groups: root canal preparation with R25 Blue (25/0.08) ou X1 Blue (25/0.06), without cervical pre-flaring; R25 or X1 + cervical pre-flaring- pre-flaring with ProTaper Universal SX e S1 before instrumentation with R25 Blue or X1 blue. After instrumentation the instruments were tested for cyclic fatigue using a simulated stainless steel root canal with 86 degree bending angle and 6 mm bending radius. The instruments were triggered using the "RECIPROC ALL" motion of a reciprocating endodontic motor (VDW) and the instrumentation time until instrument fracture was accounted. Results were analyzed by Students t-test (p<0.05). Results: Statistical analysis showed that the X1 Blue showed higher resistance to cyclic fatigue than the R25 Blue under both conditions tested (p<0.05). There were no differences between the groups with and without coronary pre-flaring for the R25 Blue and X1 Blue (p<0.05). Conclusion: X1 Blue showed higher resistance to cyclic fatigue than the R25 Blue. The cervical pre-flaring did not increased the resistance to cyclic fatigue fracture of the tested instruments (AU)

Scope of Preparation of Oval and Long-Oval Root Canals: A Review of the Literature.

Successful endodontic treatment depends on cleaning and disinfecting the root canals, in order to provide conditions for three-dimensional filling, which should prevent root canal reinfection. However, anatomical complexities pose a challenge during endodontic treatment. The present study was a literature review carried out in the following databases: PubMed, SciELO, and MEDLINE, which were searched for articles published from 2017 to 2021. Micro-CT studies published in English, which analysed the capacity for preparation of oval and long-oval root canals, were included. The following keywords were used: "oval-shaped canals," "long-oval-shaped canals," "endodontics," and "micro-CT." The aim of this study was to carry out a literature review of micro-CT studies on the scope of the capacity for preparation performed in oval and long-oval root canals with rotary and reciprocating instruments.

Avaliação do nível de sujidade de sistemas rotatório e reciprocante após instrumentação e procedimentos de limpeza pré-esterilização / Evaluation of the dirt level of rotary and reciprocating systems after instrumentation and pre-sterilization cleaning procedures

Objetivos: avaliar a sujidade de limas rotatórias e reciprocantes após instrumentação e procedimentos de limpeza pré-esterilização. Materiais e métodos: 24 limas rotatórias e as 24 limas reciprocantes foram divididas, aleatoriamente, em dois grandes grupos. No primeiro grupo, as 12 limas rotatórias e as 12 limas reciprocantes foram divididas, aleatoriamente, em seis subgrupos (SG): SG1 (controle negativo 1/n=1) ­ 1 lima rotatória não submetida à instrumentação; SG2 (controle negativo 2/n=1) ­ 1 lima reciprocante não submetida à instrumentação; SG3 (controle positivo 1/n=1) ­ 1 lima rotatória submetida à instrumentação e não submetida a qualquer protocolo de limpeza; SG4 (controle positivo 2/n=1) ­ 1 lima reciprocante submetida à instrumentação e não submetida a qualquer protocolo de limpeza; SG5 (grupo teste/n=10) ­ 10 limas rotatórias submetidas à instrumentação e submetidas ao protocolo de lavagem manual; SG6 (grupo teste/ n=10) ­ 10 limas reciprocantes submetidas à instrumentação e submetidas ao protocolo de lavagem manual. No segundo grupo, as 12 limas rotatórias e as 12 limas reciprocantes foram divididas, aleatoriamente, nos mesmos subgrupos, substituindo, nos subgrupos 5 e 6, a lavagem manual pela lavagem em cuba ultrassônica. A análise do nível de sujidade foi realizada por microscopia eletrônica de varredura (MEV), sendo os dados submetidos ao teste de Kruskal-Wallis, com nível de significância de 5%. Resultados: a menor média de sujidade entre os grupos experimentais foi encontrada no SG5 do G1, sem diferença significante em relação aos demais grupos testados (p>0,05). Conclusão: conclui-se que os protocolos de limpeza testados não foram completamente efetivos para a remoção de sujidade das limas endodônticas.(AU)

Objective: to evaluate the dirt of rotary and reciprocating files after instrumentation and pre- -sterilization cleaning procedures. Materials and Methods: 24 rotary files and the 24 reciprocating files were randomly divided into two groups. In the 1st group, 12 rotary files and 12 reciprocating files were randomly divided into six subgroups (SG): SG1 (negative control 1/n=1) ­ 1 rotary file not subjected to instrumentation; SG2 (negative control 2/n=1) ­ 1 reciprocating file not subjected to instrumentation; SG3 (positive control 1/n=1) ­ 1 rotary file submitted to instrumentation and not submitted to any cleaning protocol; SG4 (positive control 2/n=1) ­ 1 reciprocating file submitted to instrumentation and not submitted to any cleaning protocol; SG5 (test group/n=10) ­ 10 rotary files submitted to instrumentation and submitted to the manual cleaning protocol; SG6 (test group/n=10) ­ 10 reciprocating files submitted to instrumentation and submitted to the manual cleaning protocol. In the 2nd group, the 12 rotary files and the 12 reciprocating files were randomly divided into the same subgroups, substituting, in subgroups 5 and 6, manual with ultrasonic bath cleaning. The analysis of dirt levels was performed by scanning electron microscopy (SEM), being the data submitted to the Kruskal-Wallis test, with a significance level of 5%. Results: the lowest average of dirt between the experimental groups was found in SG5 of G1, with no significant difference when compared to the other groups (p>0.05). Conclusion: it could be concluded that the cleaning protocols were not completely effective in removing dirt from endodontic files.(AU)

Estudio comparativo de los tiempos registrados por los instrumentos TruNatomy y ProTaper Next para alcanzar la longitud de trabajo en conductos curvos simulados obturados con GuttaCore / Comparative study of the times recorded by the TruNatomy and ProTaper Next instruments to reach the working length in simulated curved canals filled with GuttaCore

Objetivo: Comparar el tiempo empleado por los instrumen- tos TruNatomy Medium y ProTaper Next X3 para penetrar hasta la longitud de trabajo la masa de obturaciones realizadas con Gut- taCore Primary y sellador en conductos curvos simulados. Materiales y métodos: Se prepararon 20 conductos curvos simulados con instrumentos rotatorios WaveOne Gold Primary y se obturaron con GuttaCore Primary y AH Plus. Las muestras fueron divididas en dos grupos de 10 cada uno. Grupo 1: El material de obturación fue penetrado hasta la lon- gitud de trabajo con instrumentos TruNatomy Medium. Gru- po 2: El material de obturación fue penetrado hasta la longitud de trabajo con instrumentos ProTaper Next X3. Se registraron los tiempos de penetración requeridos para cada grupo y los valores obtenidos fueron analizados mediante la prueba t de Student. Resultados: Los instrumentos ProTaper Next X3 pe- netraron la masa del material de obturación más rápidamente que los instrumentos TruNatomy MediumTM. Las diferencias observadas entre ambos instrumentos fueron estadísticamente significativas (P <0.01). Conclusión: Si bien los instrumentos ProTaper Next X3 y TruNatomy MediumTM penetraron la masa de Gutta- Core Primary de manera eficiente, ProTaper Next X3 penetró hasta la longitud de trabajo más rápidamente (AU)

Aim: Compare the time required by the instruments TruNatomy Medium and ProTaper Next X3 to penetrate up to the working length the mass of fillings made with GuttaCore Primary and sealant in simulated curved canals. Materials and methods: The simulated canals of 20 EndoTraining Blocks were prepared with WaveOne Gold Pri- mary and obturated with GuttaCore Primary and AH Plus. The sample was divided into two groups of 10 each. Group 1: The sealing material was penetrated up to working length with TruNatomy Medium. Group 2: The sealing material was penetrated up to working length with ProTaper Next X3. The penetration time was recorded in each group and the obtained values were statistically analyzed with the Student's t test. Results: ProTaper Next X3 instruments penetrated the sealing material mass faster than TruNatomy Medium. Statis- tically significant differences were observed between the two instruments (P <0.01). Conclusion: While the ProTaper Next X3 and TruNat- omy Medium penetrated the GuttaCore mass to the working length efficiently, the ProTaper Next X3 did it in less time (AU)

Root canal instrumentation efficacy of non-fused and fused primary molar roots: a micro-computed tomography study.

PURPOSE: Pulpectomy may be indicated in restorable primary teeth exhibiting irreversible pulpitis or pulpal necrosis. The purpose of this study was to compare the cleaning and shaping efficacy of NiTi systems (Reciproc® Blue and MTwo®) with manual stainless-steel instrumentation in primary molars using micro-CT analysis. METHODS: Fifty-seven maxillary second primary molars were scanned using micro-CT. Teeth with three divergent roots were divided randomly (n = 15) according to instrument type (K file, MTwo®, and Reciproc® Blue). Teeth with root fusion were instrumented manually as a separate group (n = 12). Pre- and post-instrumentation micro-CT images were superimposed, and the instrumentation area (IA) and procedural complications were recorded. RESULTS: No statistically significant differences in IA between file systems was observed in the non-fused teeth. The mean IA of fused roots was significantly lower than in the non-fused distobuccal (p = 0.003) and palatal (p < 0.001) roots. The root segment had a significant effect on IA (p < 0.001) and the highest mean IA was observed in the apical third. Manual instrumentation had fewer procedural complications compared with rotary systems. CONCLUSION: No differences were determined in the cleaning and shaping effectiveness of all systems in non-fused teeth. Uninstrumented areas (> 60%) occurred in both non-fused and fused primary teeth with fewer procedural complications observed after manual instrumentation.

Comparison Of Centering Ability And Transportation Of The Protaper Next And Oneshape File Rotary Systems For Preparing Simulated Curved Canal.

BACKGROUND: To compare the effect of ProTaper Next and One Shape rotary files on canal transportation and centering abilities in resin block with simulated curved canal. METHODS: An in-vitro experimental study was carried out in Dental clinics. Sixty resin blocks (30 per group) having simulated curved canals prepared with ProTaper Next and One Shape and then filled with red and blue Indian ink, respectively. Photographs of resin blocks obtained using standardized manner were then transferred to the Adobe Photoshop 7.0. Centering abilities and amount of transportation were then calculated at coronal, middle and apical portion of canal for both the groups. Independent sample t-test was used to compare the transportation and centering ability of both file systems. Level of significance was kept at p-value ≤0.01. RESULTS: One Shape file resulted in more canal transportation at all the levels (apical, middle and coronal part) as compared to ProTaper Next file, however, difference was not statistically significant (p-value >0.01). Statistically significant difference was noted at the apical third between these two rotary files with One Shape file showing more centered preparation as opposed to ProTaper Next file (p-value <0.01). CONCLUSIONS: One Shape file system had more centered canal preparations specifically at the apical region as compared to ProTaper Next. One Shape also lead to more canal transportation in comparison to ProTaper Next, however the difference was not statistically significant.

Efficacy of continuous apical negative ultrasonic irrigation (CANUI) in penetration of simulated lateral canals in extracted teeth.

The aim of this study was to evaluate the efficacy of continuous apical negative ultrasonic irrigation into simulated lateral canals and the apical third in straight and curved root canals. Two simulated lateral canals were created 2, 4 and 6 mm from the working length in 120 single-rooted teeth (6 canals/tooth, n = 360 straight, n = 360 curved). The teeth were randomly divided into 3 experimental groups: positive pressure irrigation (PPI) (n = 20); passive ultrasonic irrigation (PUI) (n = 20); continuous apical negative ultrasonic irrigation (CANUI) (n = 20). 20% Chinese ink was added to a 5% sodium hypochlorite solution and delivered into the root canals. The results showed a significantly higher (P < 0.05) penetration of irrigant into the lateral canals and up to working length in the CANUI group for straight and curved roots. CANUI improves penetration into the lateral canals and up to the working length of the cleared teeth in straight and curved roots.

Preventing nickel-titanium rotary instrument from breakage by continuous irrigation with different fluids during root canal preparation.

ABSTRACT: To study the effect of continuous irrigation of rotating nickel-titanium instrument with several common clinical fluids on the diameter, breaking length and breaking position of nickel-titanium instrument, so as to provide some reference and theoretical basis for clinical operation and instrument improvement.A standardized curved root canal model was established, and ProTaper Universal (PTU) F1 instrument was selected for root canal preparation. The nickel-titanium F1 instrument was flushed with distilled water, 0.9% NaCl, 0.2% chlorhexidine, 1% sodium hypochlorite and 5% sodium hypochlorite, and the diameter, length and position of the instrument before and after breakage were recorded.Only 5% sodium hypochlorite influenced the diameter of 6 mm marker points under different irrigation conditions (P < .05). There was no statistical difference in the length of broken instruments among all the groups, and torsional deformation mainly occurred at the end of broken instruments. The broken positions of instruments in all the groups were located at the bending segment of the root canal. The breaking frequency of the 5% sodium hypochlorite group was the highest in the area 3-5.5 mm away from apical foramen, while the other 4 groups had the highest breaking frequency in the area 0 to 1.5 mm away from apical foramen.External irrigation with different fluids did not influence the breaking length of instruments. The closer to the apical foramen was, the higher the breaking frequency of instruments was. However, only 5% sodium hypochlorite can affect the diameter of rotary nickel-titanium instruments, and may lead to early breakage of the instrument, indicating that the use of disinfectants, except 5% sodium hypochlorite, cannot reduce breakage resistance of nickel-titanium instrument compared with distilled water flushing. Furthermore, 5% hypochlorite could not be recommended for irrigation in clinical practice.