CYCLIC AND TORSIONAL FATIGUE RESISTANCE OF THERMALLY TREATED ROTARY NiTiINSTRUMENTS WITH DIFFERENT DESIGNS

Aims: The aim was to evaluate the cyclic and torsional fatigue resistance among thermally treated NiTi rotary instruments with different design features.Materials and methods: Sixty instruments of three systems were used (n=20): TruNatomy 26.04 (TN 26.04), BassiLogic 25.05 (BL 25.05), and Flat File 25.04 (FF 25.04). The cyclic fatigue test (n=10) was performed to evaluate the time to fracture (s) and the number of cycles until failure (NCF). The torsion test was performed to evaluate the torque (N.cm) and maximum angular deflection until fracture (n=10). The fracture surface of each fragment was examined under a scanning electron microscope. The data were analyzed by Tukey's test (p<0.05).Results: BL 25.05 and FF 25.04 instruments had a higher number of cycles and time to fracture compared with TN 26.04 (p<0.05). TN 26.04 instruments showed lower torque to fracture.Conclusions: Based on the proposed objectives and the methodology used, TruNatomy 26.04 instruments present lower resistance to cyclic fatigue and torsional fatigue when compared to BassiLogic 25.05 and Flat File 25.04 instruments.

Shaping ability of a pediatric motor-driven instrumentation system in primary molar root canal prototypes

Abstract Evaluate the shaping ability and preparation time using a pediatric motor-driven rotary instrumentation compared to other systems in resin prototypes of primary molars. Methods: Thirty specimens were scanned in micro-CT and divided into three groups according to the instrumentation type: pediatric motor-driven Sequence baby File (SBF); conventional motor-driven (Sequence Rotary File - SRF); manual K file. Instrumentation time was timed. After preparation, the specimens were scanned again. The pre- and post-instrumentation images were superimposed to measure the amount of root canal deviation and the resin remnant thickness. ANOVA followed by the Tukey test analyzed the comparisons between groups (p<0.05). Results: No statistically significant differences occurred in root canal deviation among groups (p>0.05). There were statistically significant differences in the comparison among root thirds (p<0.001) but without significant differences in the interaction group vs. root third (p>0.05). Both motor-driven instrumentations showed statistically greater weariness than manual instrumentation (p<0.001), without significant significant differences between SBF and SRF. Motor-driven instrumentation had a shorter working time than manual instrumentation (p<0.001). Conclusion: Pediatric motor-driven instrumentation demonstrated good outcomes in relation to root canal deviation and amount of remnant structure, with shorter instrumentation time. SBF can be a suitable alternative for endodontic instrumentation in primary molars.

Resumo Objetivo: Avaliar os resultados da instrumentação endodôntica e o tempo de preparo de lima odontopediátrica ativada por motor (Sequence Baby File- SBF) em canais de molares decíduos prototipados. Métodos: Trinta espécimes foram escaneados em micro-CT e divididos em três grupos de acordo com o tipo de instrumentação: mecanizada odontopediátrica (SBF); mecanizada convencional; lima K manual. O tempo de instrumentação foi cronometrado. Após o preparo, os espécimes foram escaneados novamente. As imagens pré e pós-instrumentação foram sobrepostas e a quantidade de desvio do canal radicular e a espessura de resina remanescente foram mensurados. Para as análises de comparações entre os grupos foram realizados teste ANOVA seguido do teste de Tukey (p<0,05). Resultados: Não ocorreram diferenças estatisticamente significativas entre os grupos no desvio do canal radicular (p>0,05). Houve diferenças estatisticamente significativas na comparação entre terços radiculares (p<0,001), mas sem diferenças significativas na interação grupo vs. terço radicular (p>0,05). A instrumentação mecanizada apresentou desgaste estatisticamente maior do que a instrumentação manual (p<0,001), sem diferenças estatísticas entre a SBF e a lima mecanizada convencional. A instrumentação mecanizada teve menor tempo de trabalho quando comparado a instrumentação manual (p<0,001). Conclusão: A instrumentação mecanizada odontopediátrica demonstrou bons resultados em relação ao desvio do canal radicular e quantidade de estrutura remanescente, com menor tempo de instrumentação. A SBF pode ser uma alternativa adequada para a instrumentação endodôntica em molares decíduos.

Influence of temperature on the torsional properties of two thermally treated NiTi rotary instruments

Abstract This study aimed to evaluate the influence of temperature on torsional strength and angular deflection of two experimental NiTi rotary instruments manufactured from Blue and Gold thermal treatments and with identical cross-sections. A total of 40 experimental NiTi instruments 25.06 and with a triangular cross-section and manufactured from Blue and Gold thermal treatments were used (n=20). The torsional test was performed in the 3 mm from the tip of the instrument according to ISO 3630-1. The torsional test evaluated the torsional strength and angular deflection to failure at room temperature (21°C ± 1° C) and body temperature (36°C ±1°C). The fractured surface of each fragment was observed by using scanning electron microscopy (SEM). Data were analyzed using an unpaired t test for inter and intra-group comparison and the level of significance was set at 5%. The results showed that the body temperature did not affect the torsional strength and angular deflection of the instruments when compared with room temperature (P>0.05). However, at body temperature, the Blue NiTi instruments presented significantly lower angular deflection in comparison with Gold NiTi instruments (P<0.05). There was no significant difference regarding the torsional strength of the instruments at body temperature (P>0.05). The temperature did not affect the torsional strength of the instruments manufactured from Blue and Gold technology. However, the Blue NiTi instruments presented significantly lower angular deflection than Gold instruments at 36°C temperature.

Resumo O objetivo deste estudo foi avaliar a influência da temperatura nas propriedades de torção (resistência à torção e deflexão angular) de dois instrumentos rotatórios experimentais de NiTi fabricados com secção triangu.ar e tratamentos térmicos Blue e Gold. Quarenta instrumentos experimentais de NiTi 25.06 com tratamento térmico Blue e Gold foram usados (n= 20). Foi avaliada a resistência torcional e a deflexão angular até a fratura na temperatura ambiente (21°C ± 1°C) e corporal (36°C ± 1°C). O teste torcional foi realizado nos 3 mm da ponta dos instrumentos de acordo com a ISO 3630-1. A superfície fraturada de cada instrumento foi observada pelo microscópio eletrônico de varredura (MEV). Os dados foram analisados por meio do teste t não pareado para a comparação inter e intragrupos e o nível de significância à 5%. Os resultados demonstraram que a temperatura corporal não afetou a resistência a torção e deflexão angular quando comparada com a temperatura ambiente (P>0.05). No entanto, na temperatura de 36°C o instrumento com tratamento térmico Blue apresentou menor deflexão angular quando comparado com o Gold (P<0.05). Não houve diferença significante entre os dois instrumentos em relação a resistência à torção. A temperatura corporal não modificou a resistência torcional dos instrumentos fabricados com tecnologia Blue e Gold. No entanto, os instrumentos com NiTi Blue apresentaram menor deflexão angular do que o Gold a 36°C.

Divergence between confidence and knowledge of endodontists regarding non-odontogenic pain

Abstract This study aimed to assess the self-reported levels of confidence and knowledge related to non-odontogenic pain among a group of Brazilian endodontists. Methodology A total of one hundred and forty-six endodontists affiliated with the Brazilian Society of Endodontics participated in the survey. The questionnaire, distributed via email or WhatsApp, contained inquiries designed to gauge self-perceived confidence and knowledge concerning non-odontogenic pain. The practitioners were categorized into four groups based on their self-reported familiarity with various orofacial pain types, classified as either sufficient or insufficient, and on their engagement in ongoing educational programs related to orofacial pain. Data were analyzed by Chi-Square Test and Fischer's exact test (p<0.05). Results Overall, self-reported confidence about non-odontogenic pain was high, especially for endodontists who considered their knowledge about orofacial pain sufficient, regardless of whether they had (71.1% - 97.8%) or not (35.7% - 96.4%) been continuously involved in education courses on orofacial pain. In general, self-reported knowledge about non-odontogenic pain was insufficient (0% - 42%), except in the question about how they would act in cases of pain that persists beyond the normal healing time after an endodontic procedure (70.6% - 81.9%). In general, endodontists are confident in their diagnosis and treatment of non-odontogenic pain. Nonetheless, this confidence did not correlate with a commensurate knowledge depth of. Thus, specialization courses in endodontics should highly consider training and qualifying these professionals in the diagnosis of non-odontogenic pain.

CYCLIC AND TORSIONAL FATIGUE RESISTANCE OF THREE DIFFERENT THERMALLY TREATED NICKEL-TITANIUM ROTARY INSTRUMENTS

Background: The aim of this study was to evaluate the cyclic fatigue and torsional fatigue resistance of three thermally treated rotary instruments, such as: Logic 2 25.05 (LOG 25.05), Edge Taper Platinum 25.06 (EDT 25.06) and ProTaper Gold 25.08 (PTG 25.08).Methods: A total of 60 rotary instruments of LOG 25.05, EDT 25.06 and PTG 25.08 were used (n=20). Cyclic fatigue tests were performed at 36°C using an artificial stainless steel canal with a 60ºangle and a 5-mm radius of curvature. The time (in seconds) and number of cycles to fracture (NCF) was recorded. The torsional test evaluated the torque and angle of rotation to failure at 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 Holm-Sidak's tests for multiple comparison, the level of significance was set at 5%.Results: EDT 25.06 had highest cyclic fatigue resistance (time and NFC), followed by LOG 25.05 and PTG 25.08 (P<0.05). There were no significantly difference between LOG 25.05 and ETP 25.06 regarding the NCF (P>0.05). In relation the torsional test, the LOG 25.05 and ETP 25.06 presented similar torque (P>0.05). The PTG presented greater torque than the other groups (P<0.05). The PTG 25.08 presented the lowest angular rotation to fracture than the other groups (P<0.05). The SEM images demonstrated typical features of cyclic and torsional fracture.Conclusion: In conclusion, the LOG 25.05 and ETP 25.06 presented similar cyclic and torsional properties. The PTG 25.08 showed greater torsional strength.

A biocomplex to repair experimental critical size defects associated with photobiomodulation therapy

Abstract Background: The association of scaffolds to repair extensive bone defects can contribute to their evolution and morphophysiological recomposition. The incorporation of particulate biomaterials into three-dimensional fibrin bioproducts together with photobiomodulation therapy (PBM) has potential and can improve regenerative medicine procedures. The objective of this experiment was to evaluate the effects of PBM therapy on critical size defects filled with xenogenic bone substitute associated with fibrin biopolymer. Methods: A critical defect of 8 mm was performed in 36 Wistar male adult rats that were divided into four groups. Groups BC and BC-PBM were defined as controls with defects filled by a clot (without or with PBM, respectively) and groups XS and XS-PBM that comprised those filled with biocomplex Bio-OssTM in association with fibrin biopolymer. PBM was applied immediately after the surgery and three times a week every other day, with the parameters: wavelength of 830 nm, energy density 6.2 J/cm2, output power 30 mW, beam area of 0.116 cm2, irradiance 0.258,62 W/cm2, energy/point 0.72 J, total energy 2.88 J. Fourteen and 42 days after the surgery, animals were euthanatized and subjected to microtomography, qualitative and quantitative histological analysis. Results: The BC-PBM and XS-PBM groups had a similar evolution in the tissue repair process, with a higher density of the volume of new formed bone in relation to the groups without PBM (p = 0.04086; p = 0.07093, respectively). Intense vascular proliferation and bone deposition around the biomaterial particles were observed in the animals of the groups in which biocomplex was applied (XS and XS-PBM). Conclusion: PBM therapy allowed an improvement in the formation of new bone, with a more organized deposition of collagen fibers in the defect area. Biocomplex favored the insertion and permanence of the particulate material in bone defects, creating a favorable microenvironment for accelerate repair process.

A biocomplex to repair experimental critical size defects associated with photobiomodulation therapy

The association of scaffolds to repair extensive bone defects can contribute to their evolution and morphophysiological recomposition. The incorporation of particulate biomaterials into three-dimensional fibrin bioproducts together with photobiomodulation therapy (PBM) has potential and can improve regenerative medicine procedures. The objective of this experiment was to evaluate the effects of PBM therapy on critical size defects filled with xenogenic bone substitute associated with fibrin biopolymer. Methods: A critical defect of 8 mm was performed in 36 Wistar male adult rats that were divided into four groups. Groups BC and BC-PBM were defined as controls with defects filled by a clot (without or with PBM, respectively) and groups XS and XS-PBM that comprised those filled with biocomplex Bio-OssTM in association with fibrin biopolymer. PBM was applied immediately after the surgery and three times a week every other day, with the parameters: wavelength of 830 nm, energy density 6.2 J/cm2, output power 30 mW, beam area of 0.116 cm2, irradiance 0.258,62 W/cm2, energy/point 0.72 J, total energy 2.88 J. Fourteen and 42 days after the surgery, animals were euthanatized and subjected to microtomography, qualitative and quantitative histological analysis. Results: The BC-PBM and XS-PBM groups had a similar evolution in the tissue repair process, with a higher density of the volume of new formed bone in relation to the groups without PBM (p = 0.04086; p = 0.07093, respectively). Intense vascular proliferation and bone deposition around the biomaterial particles were observed in the animals of the groups in which biocomplex was applied (XS and XS-PBM). Conclusion: PBM therapy allowed an improvement in the formation of new bone, with a more organized deposition of collagen fibers in the defect area. Biocomplex favored the insertion and permanence of the particulate material in bone defects, creating a favorable microenvironment for accelerate repair process.(AU)

Evaluation of in vitro experimental model for analysis of bioceramic sealers

Abstract This study aimed to evaluate physicochemical properties of three ready-to-use calcium silicate-based endodontic sealers: Endosequence BC Sealer, Bio C Sealer, and Sealer Plus BC. Radiopacity was evaluated using specimens of 10 mm in diameter and 1 mm in height, along with an aluminum step wedge. For the flow test, 0.5 mL of each sealer was deposited between glass plates and the mean of the measurement of two diameters was considered the cement flow value. For pH and calcium release, root canals of 30 prototypes of upper incisor acrylic resin teeth were filled with sealer and gutta percha point and then immersed in containers with 13 mL of ultrapure water. Both pH and release of calcium ions (atomic absorption spectrophotometer) were measured at 3, 24, 72, and 168 h. Acrylic resin teeth were scanned by Micro-CT 1174 at the time of pH and calcium ion readings for volumetric change analysis. The data were analyzed by ANOVA, Tukey's, Kruskal-Wallis, and Dunn's tests. Endosequence BC Sealer presented the lowest, and Bio C Sealer the highest volumetric change after 72 h and 168 h (p < 0.05). Endosequence BC Sealer presented higher radiopacity (p < 0.05). All materials showed alkalinization capacity. All of them presented calcium ion release, with a higher value for Sealer Plus BC. All materials presented alkalinization, calcium release capacity, radiopacity, and flow above the minimum values required by the ISO standard. The highest volumetric loss was experienced by Bio C Sealer and the lowest one by Endosequence BC Sealer.

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.

Procedimentos regenerativos endodônticos com clorexidina a 2% e hidróxido de cálcio: relato de caso / Endodontic regenerative procedures with 2% chlorhexidine and calcium hydroxide: case report

Introdução: Muitas substâncias têm sido utilizadas como irrigantes e curativos intracanal nos tratamentos de dentes com rizogênese incompleta, visando obter a regeneração pulpar. A clorexidina a 2% em associação com hidróxido de cálcio P.A. pode ser uma alternativa. Métodos: No presente caso clínico, o dente #45 com periodontite apical, em um paciente com 13 anos de idade, foi tratado com solução de clorexidina a 2% como irrigante. A clorexidina na forma de gel a 2% foi utilizada como auxiliar da instrumentação e, em associação com o hidróxido de cálcio, foi utilizada como curativo durante 14 dias. Após esse período, o canal foi irrigado com solução fisiológica e, sob anestesia alveolar mandibular, uma lima K #70 foi utilizada ultrapassando levemente o ápice, para causar sangramento. Após observar que o sangue dentro dos canais alcançou a porção cervical, o cimento biocerâmico MTA Branco foi colocado na porção cervical do canal. Resultados: A apicificação e o desenvolvimento da raiz em comprimento e largura puderam ser observados já no controle de três meses, e continuaram até a última revisão, no controle de um ano. Alterações de cor não foram observadas nese período de acompanhamento. Conclusões: A clorexidina associada ao hidróxido de cálcio pode ser uma alternativa aos procedimentos de regeneração pulpar (AU).

Introduction: Many substances have been used as irrigating solutions to promote pulp regeneration and root development in teeth with incomplete rhizogenesis. The use of 2% chlorhexidine as an irrigating solution in association with Calcium Hydroxide could be an alternative. Methods: In the case of the patient, a 13-year-old boy, here presented, tooth 45 with apical periodontitis was treated with 2% Chlorhexidine solution as irrigant adjuvant to instrumentation, in association with Calcium Hydroxide used as a dressing for 14 days. After this period, the canal was cleaned with a physiological solution and under mandibular alveolar anesthesia, a # 70 K file was used slightly over the apex to cause bleeding. After observing that blood inside the canals had reached the cervical portion. White MTA was placed in the cervical portion of the canal. Results: Induced apexification and development of increasing root length and width could already be observed in the three-month control exam, and this continued until the last review in the one-year control exam. No color changes were observed in this follow-up period. Conclusions: Chlorhexidine and calcium hydroxide could be used as an alternative to pulp regeneration procedures (AU).

Successful revascularization procedure in an immature permanent necrotic second lower molar: a case report with 4. 5- years follow- up

Background: Infection control is mandatory for revascularization procedures, enabling to eliminate patient's clinical symptoms and signs. Despite presenting a complex morphology when compared to anterior teeth, if a strict disinfection protocol is adopted and the revascularization procedure's biological principles are followed, the therapy can be successful in molar teeth. Methods: This case report aims to present a clinical case of successful revascularization in an immature permanent necrotic second lower molar. Clinical decisions and explanations regarding possible mechanisms related to the treatment's success in a tooth with complex morphology are discussed. Results: Revascularization procedures were performed on a 12-year-old male patient diagnosed with symptomatic periapical periodontitis in a tooth 37. The case highlights the need for infection control and biological principles that surrounds the success of this therapy. Follow-up times presented in this case were six months, 1, 2, 4 and 4.5-years, respectively. Continued root development was observed, and the tooth remains intact and without symptoms. Conclusion: The association of infection control and the biological principles of revascularization procedures allow the maintenance and continuation of tooth development, even when these present complex morphologies.

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).

Uso da tecnologia e cimento de silicato de cálcio na resolução de complicações no retratamento endodôntico: relato de caso / Use of technology and calcium silicate cement in the resolution of endodontic retreatment complications: Case report

Introdução: Acidentes e complicações podem acontecer em qualquer fase do tratamento endodôntico. Podem ocorrer devido a diversos fatores, como falhas dos instrumentos, dificuldades anatômicas e limitações do profissional, o que, muitas vezes, pode alterar o prognóstico de um caso. Objetivo: O presente relato de caso aborda uma situação em que uma paciente se apresentava com dois instrumentos fraturados e uma perfuração radicular em um dente molar inferior com periodontite apical. Relato do caso: Os fragmentos foram removidos por meio de técnica mecanizada e ultrassônica padronizada, e a perfuração foi tratada e selada com material à base de silicato de cálcio. Conclusão: O emprego de recursos tecnológicos atuais favoreceu a resolução do caso, melhorando seu prognóstico. O restabelecimento da condição de normalidade do dente e tecidos adjacentes foi confirmado por exames radiográficos e tomográficos (AU).

Introduction: Accidents and complications may happen at any endodontic treatment stage. These are likely to change the prognosis of treatment and can be due to factors related to instrumental failure, anatomic difficulties and the professional's limitations. Objective: This case report addresses a case where a patient presenting two separated instruments and a root perforation in a lower molar with apical periodontitis. Case report: The separated instruments have been removed by mechanical and ultrasonic standardized method and the perforation was treated and sealed by silicate cement-based material. Conclusion: The use of technological resources favored the resolution of the case, increasing its predictability. The reestablishment of the normal condition of the tooth and surrounding tissues was confirmed by radiograph and computed tomography exams (AU).

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).

Resistência à fadiga cíclica dos instrumentos Reciproc e Mtwo nos movimentos rotatório e reciprocante / Resistance to cyclic fatigue of Reciproc and Mwto files on continuous rotation and reciprocating movements

Objetivo: O objetivo do presente estudo foi avaliar a influência da liga (NiTi convencional e M-Wire) e do movimento (reciprocante e rotação contínua) na resistência à fadiga cíclica. Métodos: Quinze limas Reciproc R25 (VDW GmbH, Munique, Alemanha) foram usadas em movimento reciprocante (MR), enquanto trinta limas Mtwo 25.07 (VDW GmbH, Munique, Alemanha) foram usadas em MR (n=15) ou em rotação contínua (RC) (n=15). Os instrumentos foram submetidos a ensaios dinâmicos movidos por motor elétrico, que permitiram reproduzir o movimento de pecking motion, a 300rpm de velocidade. Os instrumentos simularam a instrumentação de um canal radicular curvo com 40o e 5mm de raio de curvatura. A fratura dos instrumentos foi detectada por um sensor digital, e o tempo e o número de ciclos foram registrados. Os dados foram analisados estatisticamente pelos testes ANOVA e de Tukey (p<0,05). Resultados: Os instrumentos Reciproc R25 movidos por MR alcançaram número significativamente maior (p<0,05) de ciclos antes da fratura (1.777,68±334,2 ciclos), quando comparados aos instrumentos MT 25.07 movidos por MR (610,67±126,3 ciclos) ou RC (432,23±183,2 ciclos). Conclusões: O movimento reciprocante mostrou resistência à fadiga cíclica significativamente maior, e os instrumentos de NiTi M-Wire apresentaram maior resistência à fadiga cíclica do que os instrumentos rotatórios de NiTi convencional (AU).

Objective: The aim of present study was to evaluate the influence of alloy (conventional NiTi and M-Wire NiTi) and movement (reciprocating movement and continuous rotation) on resistance to cyclic fatigue. Methods: Fifteen Reciproc R25 files (VDW GmbH, Munich, Germany) were used in reciprocation motion (RM), while thirty MTwo 25/.07 files (VDW GmbH, Munich, Germany) were used either in RM (n=15) or in continuous rotation (CR) (n=15). The files were submitted to dynamic assays device moved by electric engine that allowed the reproduction of pecking motion under 300 rpm of speed. The files act simulating the instrumentation of a curved root canal with 40º and 5-mm of curvature radius. The fracture was detected by the device sensor and the time and number of cycles were obtained. Data were statistically analyzed by ANOVA and Tukeys tests (p<0.05). Results: The Reciproc R25 instruments moved by RM reached significantly higher number (p<0.05) of cycles before fracture (1777.68 ± 334.2 cycles) when compared with MTwo 25/.07 instruments moved by RM (610.67 ± 126.3 cycles) or CR (432.23 ± 183.2 cycles). Conclusions: The reciprocation motion showed significantly greater cyclic fatigue resistance and the M-Wire NiTi files showed higher cyclic fatigue resistance than conventional NiTi rotary files (AU).

Influência da velocidade de rotação na resistência à fadiga cíclica do sistema rotatório Logic / Influence of the rotational speed on the cyclic fatigue resistance of the Logic rotary system

O objetivo do presente trabalho foi avaliar a influência da velocidade de rotação na resistência à fadiga cíclica do instrumento rotatório Logic 25.06 (LOG 25.06; Easy Equipamentos Odontológicos, Belo Horizonte, Brasil). Métodos: Foram utilizados 20 instrumentos rotatórios Logic 25.06 (n=10). O teste de fadiga cíclica foi realizado em um aparato com um canal artificial de aço inoxidável com ângulo de curvatura de 60° e raio de 5 mm. Os instrumentos foram utilizados a 950 e 550 rotações por minuto (RPM), sendo mensurados o tempo e o número de ciclos para a fratura. Os dados foram analisados estatisticamente por meio do teste t de Student, sendo selecionado um nível de significância de 5%. Resultados: O teste de fadiga cíclica demonstrou que a velocidade de 550 RPM promoveu um aumento significativo no tempo e no número de ciclos para a fratura dos instrumentos LOG 25.06 (p<0,05). Houve um aumento de 95,9% no tempo e de 27,25% do número de ciclos para a fratura. Conclusão: Os resultados desse estudo demonstraram que a velocidade de rotação possui uma influência significativa na resistência à fadiga cíclica dos instrumentos rotatório Logic 25.06. A velocidade de 550 RPM é uma velocidade mais segura, aumentando significativamente a resistência à fadiga cíclica (AU).

Objective: The aim of this study was to evaluate the influence of rotational speed on the cyclic fatigue resistance of Logic 25.06 rotary instruments (LOG 25.06; Easy Equipamentos Odontológicos, Belo Horizonte, Brazil). Methods: 20 Logic 25.06 instruments were used (n=20). The cyclic fatigue test was performed in an artificial canal made of stainless steel with 60° of curvature and 5 mm of radius. The instruments were activated 950 and 550 rotations per minute (RPM) until the fracture occurred. The time (in seconds) and the number of cycles to fracture (NCF) were measured. The data were statistically analyzed using One-way ANOVA and Tukey Test, the level significance used was 5 %. Results: the 550 RPM promoted a significantly higher time and NCF of LOG 25.06 in comparison with 950 RPM (P>0.05). The time increased in 95.9% and the NCF 27.25%. Conclusion: The results of this study showed that the rotational speed had a significant influence on the cyclic fatigue resistance of the Logic 25.06 rotary instruments. The 550 RPM rotational speed seems to be safer than 950 RPM, increasing the cyclic fatigue resistance of Logic 25.06 (AU).

Limitation of diagnostic value of cone-beam CT in detecting apical root isthmuses

Abstract Isthmuses are reported as common anatomic complexities in teeth often associated with failures in endodontic treatment. They should be considered before starting treatment and a preoperative computed tomography scan (CT) may demonstrate these complexities. Objective To assess the diagnostic value of the highest resolution settings of a cone-beam CT (CBCT) system in identifying and measuring apical isthmuses, using micro-CT as reference. Methodology After micro-CT scanning, 40 humans' lower first molars with isthmuses in the apical-3 mm of mesial roots were scanned by the highest resolution settings of the New Generation i-Cat ® CBCT equipment. Two blinded observers recorded the detection of isthmuses in CBCT scans. The lengths of isthmuses were compared between micro-CT and CBCT to assess the diagnostic value of CBCT. Quantitative data for sensitivity were represented as percentages (95% confidence interval). The Bland-Altman method was used to assess differences between gold standard lengths (micro-CT) and CBCT lengths. Results BCT demonstrated 30 positive findings, representing sensitivity for isthmus identification of 75% (95% CI=0.4114-1.1364). Differences between the lengths in micro-CT (1.99±0.40 mm) and CBCT (1.53±0.41 mm) were significant (p<0.0001). Conclusion The CBCT device used presented limited diagnostic value in the identification and measurement of apical isthmuses in the mesial roots of lower molars. In some cases, the actual anatomy of the apical root canal may not be completely delineated in this type of CBCT system, even using the highest resolution settings.

Torsional fatigue strength of reciprocating and rotary pathfinding instruments manufactured from different NiTi alloys

Abstract To evaluate the torsional properties of engine-driven pathfinding instruments manufactured from different NiTi alloys - R-Pilot (tip size 12.5;.04 taper; M-Wire) and One G (tip size 14;.03 taper; Conventional NiTi). A total of 40 NiTi instruments from engine-driven pathfinding instruments (n = 20) were used. The torsion tests followed ISO 3630-1 (1992). Three millimeters of each instrument tip was fastened to a small load cell by a lever arm linked to the axis of torsion. During the test, the torsion testing machine software measured the maximum torsional strength and angle of rotation (0) before instrument failure. The fractured surface of each instrument was assessed by scanning electron microscopy (SEM). In addition, a supplementary examination was performed to measure the cross-sectional area and the metal mass volume of each instrument 3 mm from the tip. Data were analyzed using a t-test, with significance level set at 5%. R-pilot had significantly higher torsional strength than did One G (p < 0.05). Regarding the angle of rotation to fracture, One G had higher angles than did R-Pilot (p < 0.05). The supplementary examination showed that R-Pilot had the highest cross-sectional area and volume of metal mass at 3 mm from the tip (p < 0.05). R-pilot (M-Wire NiTi alloy) had a significantly higher torsional strength and One-G (superelastic NiTi alloy) had the highest angle of rotation to fracture.

Ultrasonic tips as an auxiliary method for the instrumentation of oval-shaped root canals

Abstract To evaluate the influence of novel ultrasonic tips as an auxiliary method for the rotary preparation of flattened/oval-shaped canals. Forty-five mandibular incisors were selected and divided into one of three experimental groups (n = 15): Group PFCP - ProDesign Logic 25/.05 + Flatsonic + Clearsonic + Prodesign Logic 40/.01; Group FCP - Flatsonic + Clearsonic + ProDesign Logic 40/.01; and Group PP - Prodesign Logic 25/.05 + Prodesign Logic 40/.05. The teeth were scanned preoperatively and postoperatively using microcomputed tomography. The percentage values for increase in volume, non-instrumented surface area, dentin removal, degree of canal transportation, and centering ratio between the experimental groups were examined. Data were analyzed using the non-parametric Kruskal-Wallis and Dunn's tests (p < 0.05). Group PFCP showed the greatest volume increase in the total portion of the root canal and the lowest percentage of non-instrumented surface area. Regarding the degree of transportation in the buccolingual direction, statistically significant differences between groups PFCP and PP were observed at the coronal third of the canal. In the mesiodistal direction, no statistically significant differences were observed at the coronal, middle, and apical thirds. As for the centering ratio, statistically significant differences were found in the buccolingual direction. In the mesiodistal direction, no statistically significant differences were observed at the coronal, middle, and apical thirds. The use of novel ultrasonic tips combined with rotary instruments in group PFCP provided a significant increase in volume and reduced the percentage of non-instrumented areas during the preparation of flattened/oval-shaped canals.

Análise do EDTA tetrassódico associado ao hipoclorito de sódio no preparo biomecânico dos canais radiculares e em protocolos de irrigação final / Analysis of tetrasodium EDTA associated with sodium hypochlorite in the preparation biomechanical parameters of root canals and in final irrigation protocols

Introdução: O objetivo deste estudo foi avaliar a associação do hipoclorito de sódio e EDTANa4 como irrigante comparado ao EDTANa3 quanto a capacidade de limpeza, preparo biomecânico e na irrigação final, associados ou não com a agitação ultrassônica. Materiais e Método: Foram utilizados 40 pré-molares inferiores, instrumentados e analisados em MEV para comprovar a formação de smear-layer. Realizou-se então os protocolos de irrigação utilizando diferentes associações, associadas ou não a agitação ultrassônica. Resultados: O EDTA trissódico agitado ou não com ultrassom, favoreceu limpeza significante (P<0.05) apenas nos terços médio e cervical, enquanto que para o EDTA tetrassódico sem agitação a limpeza foi significante (P<0.05) apenas no terço médio. Comparando os irrigantes, independente do método de irrigação, houve diferença estatisticamente significante (P<0.05) apenas no terço médio na comparação entre o EDTA trissódico pela irrigação convencional e EDTA tetrassódico pela irrigação convencional. Conclusão: O EDTA trissódico favoreceu uma melhor limpeza em relação ao EDTA tetrassódico, principalmente no terço médio. Além disso, a agitação ultrassônica não favoreceu melhor limpeza de parede em relação à irrigação convencional.

AIM: The aim of this study was to evaluate the efficacy of Sodium Hypochlorite associated or not with Tetrasodium EDTA in smear layer removal during root canal preparation. Additionally, to compare the cleaness of dentin walls after a final irrigation of Trisodium EDTA and Sodium Hypochlorite associated with Tetrasodium EDTA, activated or not by utrasonic. Methods: 40 mandibular premolars were used, which were divided in 2 groups (n=20). G1 the root canals were instrumented using Sodium hypochlorite and G2 using Sodium hypochlorite associated with Tetrasodium EDTA. Then, the dentin walls were analyzed by Scanning Electron Microscopy (SEM) to assess presence or not of smear-layer. After this step, it was performed a final irrigation of Trisodium EDTA and Sodium Hypochlorite associated with Tetrasodium EDTA, activated or not by utrasonic. Results: The was no significantly difference between the Sodium Hypochlorite and Sodium Hypochlorite associated with Tetrasodium EDTA during root canal preparation (P>0.05). Regarding the final irrigation, the Trisodium EDTA presented significantly difference when activated ultrasonic in the coronal and middle thirds (P<0.05). The association of Sodium Hypochlorite and Tetrasodium EDTA presented significantly difference only in the middle third without ultrasonic activation (P<0.05). In general, the Trisodium EDTA favoured better smear layer removal than Tetrasodium EDTA. Conclusion: The Trisodium EDTA favored a better smear layer ramoval than Tetrasodium EDTA, mainly in the middle third. In addition, ultrasonic activation improved the smear layer removal in comparison with conventional irrigation.