The Role of Pecking Motion Depths in Dynamic Cyclic Fatigue Resistance: In Vitro Study.

OBJECTIVE: This is the first study evaluating the impact of different pecking motion depths on dynamic cyclic fatigue resistance of different endodontic instruments. METHODS: Four nickel-titanium systems (Hyflex EDM OneFile 25/. ∼; Rotate 25/0.6; Mtwo 25/0.6; Reciproc Blue R25) were tested. Forty instruments from each group were subjected to 4 different pecking movements to evaluate their cyclic fatigue resistance. The distances for the pecking motion were 3-mm forward and backward, 1-mm (3-mm forward and 2-mm backward), 2-mm (4-mm forward and 2-mm backward), and 3-mm (5-mm forward and 2-mm backward). Speeds were 100 and 200 mm/min for the descending and ascending motion, respectively. The times to fracture (TtF) in seconds were recorded for each instrument. Data were statistically analysed by using 2-way ANOVA and Bonferroni multiple comparison post hoc test (P < .05). RESULTS: All instruments had a significant increase in cyclic fatigue resistance during the forward dynamic motion compared with the axial continuous. Overall, the heat-treated instruments reported higher fatigue strength than the untreated files (P < .05). Reciproc Blue and Hyflex EDM showed higher TtF in the forward movements of 1-/2-mm and 2-mm (P < .05), respectively while Mtwo 25.06 and Rotate 25.06 in the forward movement of 3-mm (P < .05). CONCLUSIONS: Within the limits of this in vitro study, the pecking motion depths had varying impacts on the cyclic fatigue resistance of instruments. Reciproc Blue and Hyflex EDM performed significantly better with pecking motions of 1-and 2-mm. Improving endodontic instrument durability through specific pecking depths has the potential for improving clinical performance and reducing instrument failures.

Remoção Manual não Cirúrgica de Instrumento Endodôntico Fraturado no Terço Apical de Pré-Molar Superior: Relato de Caso / Surgical Manual Removal of Fractured Endodontic Instrument in the Apical Third of Maxillary Premolar: Case Report

A fratura acidental de um instrumento durante o tratamento endodôntico pode ocorrer devido à falta de conhecimento anatômico do elemento dentário, ao uso de instrumentos inadequados ou à falha técnica do operador. O objetivo do presente estudo foi apresentar um relato de caso clínico da remoção de um instrumento fraturado no terço apical de um pré-molar superior. O fragmento localizava-se no terço apical da raiz vestibular. A primeira tentativa de remoção do fragmento foi realizada sem sucesso. Após 15 dias, em uma nova tentativa, o instrumento foi removido com o auxílio de ultrassom e inserto específico. Entre as sessões, utilizou-se medicação intracanal à base de hidróxido de cálcio, paramonoclorofenol canforado e propilenoglicol. Decorridos 15 dias, o dente mostrou-se assintomático e foi obturado pela técnica da condensação lateral. Assim, a paciente foi encaminhada para a realização da restauração definitiva. Após 3 meses, foi observada radiograficamente a regressão da lesão perirradicular. Conclui-se que a retirada do fragmento no caso descrito se mostrou uma opção eficiente, propiciando a manutenção do dente com ausência de sinais e sintomas.

Accidental fracture of an instrument during endodontic treatment can occur due to lack of dental anatomy knowledge, use of inadequate instruments or technical failure of the operator. The aim of the present study is to present a case report of instrument fragment removal from a superior premolar. The fragment was identified to be in the apical third of the buccal root. The first attempt to remove the instrument was made without success. After 15 days, in a new attempt, the instrument was removed with the aid of an ultrasonic endodontic tip. The intracanal medication between sessions was calcium hydroxide, camphorated paramonochlorophenol and propylene glycol. After more 15 days, the tooth was asymptomatic and was filled by lateral condensation. Thus, the patient was referred for definitive restoration. After 3 months, it was observed radiographically the regression of the periradicular lesion. In conclusion, the removal of the fragment proved to be an efficient option, providing the maintenance of the tooth with no signs and symptoms.

Obturation Over an S1 ProTaper Instrument Fragment in a Mandibular Molar with Three Years of Follow-up

This case report describes root canal filling performed over a large S1 ProTaper file fragment in a second mandibular molar with irreversible pulpitis. An S1 ProTaper file was fractured during the instrumentation of the mesiobuccal canal. Approximately 10 mm of file fragment remained in the apical and middle thirds of the canal. The obturation was performed over this fragment using thermomechanically compacted gutta-percha and sealer. Radiographic findings and the absence of clinical signs and symptoms at 3-year follow up indicated successful treatment. Cone-beam computed tomography images revealed absence of periapical lesion and details of intracanal file fragment related to root fillings and apex morphology. In this case, the presence of a large intracanal fractured instrument did not have a negative impact on the endodontic prognosis during the follow up evaluation period.

Este relato de caso descreve a obturação do canal radicular realizada sobre um grande fragmento da lima ProTaper S1 em um segundo molar inferior com pulpite irreversível. Uma lima ProTaper S1 fraturou durante a instrumentação do canal mésio-vestibular. Aproximadamente 10 mm de remanescente do fragmento da lima permaneceu nos terços apical e médio do canal. A obturação foi realizada sobre este fragmento usando guta-percha compactada termomecanicamente e cimento endodôntico. Achados radiográficos e ausência de sinais e sintomas clínicos após 3 anos de acompanhamento indicaram o sucesso do tratamento. Imagens de tomografia computadorizada de feixes cônicos revelaram a ausência de lesão periapical e detalhes do fragmento da lima intracanal relacionados à obturação do canal radicular e à morfologia do ápice. Neste caso, a presença de grande instrumento fraturado intracanal não teve impacto negativo no prognóstico endodôntico durante o período de acompanhamento.

Evaluación del sellado apical de tres técnicas de obturación en presencia de instrumentos rotatorios de NiTi fracturados / Assessment of apical sealing of three warm obturation techniques in the presence of fractured NiTi rotary instruments

El propósito de este estudio fue comparar la capacidad de sellado de tres técnicas de obturación con gutapercha termoplastificada, técnica de obturación vertical de Schilder, compactación termomecánica y Thermafil (Dentsply-Maillefer), en dientes con instrumentos fracturados en la región apical. Un total de 30 dientes unirradiculares extraídos fueron instrumentados con ProTaper (Dentsply-Maillefer), en cada uno de los mismos se fracturaron intencionalmente instrumentos rotatorios ProTaper F3 en el tercio apical. Los dientes fueron divididos aleatoriamente en tres grupos (n = 10) para ser obturados con la técnica correspondiente, para que, con la técnica de filtración de colorante y con la ayuda de la aclaración de los dientes fueran observados bajo microscopio para determinar la cantidad de microfiltración apical que permitía cada técnica. En todos los grupos, los especímenes presentaron alguna cantidad de microfiltración apical. Los dientes que fueron obturados con Thermafil presentaron una microfiltración promedio de 3,134 μm, resultando en significativamente mayor microfiltración que los obturados con la técnica termomecánica de McSpadden y de compactación vertical de Schilder, (p < 0.05) que obtuvieron un promedio de microfiltración de 1,934 μm y 2,083 μm respectivamente. Mientras que no existe diferencia estadísticamente significativa de microfiltración entre la técnica de McSpadden y la de Schilder (p > 0.05).

The purpose of the present study was to compare the sealing ability of three warm obturation techniques (thermo-plasticized gutta-percha): Schilders warm vertical compaction, McSpadden's thermo-mechanical compaction and Thermafil (Dentsply-Maillefer) in teeth fractured at the apical region. 30 extracted, single-rooted teeth were prepared with Pro-Taper (Dentsply-Maillefer). At the apical third of each of these teeth, ProTaper F3 rotary instruments were deliberately fractured. Teeth were randomly divided into three groups (n = 10) to be later filled with the selected technique, so that with dye penetration technique and with the aid of discoloring teeth technique, teeth could be microscopically assessed so as to determine the amount of apical microfiltration elicited in every technique. In all groups, specimens presented some degree of apical microfiltration. Teeth filled with Thermafil presented 3,134 µm average microfiltration. This microfiltration was significantly higher than the one observed with McSpadden thermo-mechanical technique and Schilder's vertical compaction technique (p < 0.05). These two techniques presented 1,934 µm and 2,083 µm respectively. McSpadden and Schilder's technique show no statistically significant microfiltration differences (p > 0.05).