Avaliação ex vivo da precisão de um localizador apical antes e após o pré-alargamento das paredes dos canais sob a influência de diferentes substâncias irrigadoras / Evaluation ex vivo precision of an apex locator before and after pre-flaring of the root canals under the influence of different irrigants

O objetivo desse trabalho foi avaliar, ex vivo, a influência do peróxido de hidrogênio (H 2 O 2 ) a 3,0% e do hipoclorito de sódio (NaOCl) a 2,5% e 5,25% na precisão das medidas obtidas por um localizador apical eletrônico antes e após o pré-alargamento. Foram utilizadas 25 raízes mesiais de primeiros molares inferiores, totalizando 50 canais radiculares, que tiveram as coroas cortadas na junção amelocementária. A medida real de cada canal foi realizada e, em seguida, as amostras foram incluídas em uma mistura de alginato, usada como meio condutor, onde foram realizadas as medições eletrônicas com o localizador apical auxiliadas com o uso das três soluções irrigadoras antes e após o desgaste do terço médio e cervical dos canais com brocas Gates-Glidden. As medidas obtidas pelo método eletrônico foram então comparadas com a medida real dos canais. Os resultados obtidos foram tabulados e submetidos ao teste estatístico t de Student. Os resultados revelaram que não houve significância estatística (p>0,05) entre as leituras obtidas antes e após o desgaste dos terços cervical e médio dos canais com uso de NaOCl 2,5 e 5,25%, com resultados demonstrando, em média, leituras mais próximas do comprimento real do canal no grupo sem pré-alargamento. Porém, observamos diferença estatística com uso de H 2 O 2 (p<0,05) entre as leituras obtidas tanto antes quanto após o desgaste dos dois terços iniciais do canal. Desta forma, conclui-se que o preparo médio-cervical com brocas Gates Glidden não foi capaz de interferir significativamente na precisão do localizador apical testado

The aim of this paper was to evaluate the influence of 3% hydrogen peroxide (H 2 O 2 ) and 2.5% and 5.25% sodium hypochlorite (NaOCl) measured by a root apex locator before and after the pre-flaring of the root canal. The mesial root of twenty five mandibular first molars, total of 50 root canals, was tested with the crown cut off from the enamel-cementum junction. The real measure of each root was defined and after that the samples were stored in a mix of alginate, used as a conductor. The measures were done with a root apex locator using three different irrigation solutions before and after the instrumentation of the medium and cervical parts of the roots by means of Gates-Glidden drills. The measures obtained by the electronic method were compared to the real length of each root canal. These data were evaluated by means of the student t test for statistical analysis that demonstrate no statistical differences between the measures before and after the pre-flaring using 2.5% or 5.25% sodium hypochlorite (p>0.05). The results showed measures closer to the actual root canal length in the group without the pre-flaring, however statistical significance was observed with 3% hydrogen peroxide between the measures done before and after the root canal pre-flaring (p<0.05). Thus, we concluded that the medium and cervical preparation with Gates-Glidden drills was not able to interfere in the root apex locator precision

Effectiveness of an electronic apex locator used after preflaring of cervical and middle third

Introduction: The electronic method has been studied and improved aiming to add precision, speed and reliability of the measurement technique to determine the exact location of the working length. Currently, the root canal preparation recommends prior to determine the tooth length and consequent perform instrumentation of the apical portion, a previous preflaring of the cervical and middle thirds in various techniques. This procedure may provide a reduction in system impedance, leading to read errors by the apex locators. Objective: Investigate the influence of preflaring of the cervical and middle thirds on the accuracy of measuring the working length by apex locators. Material and methods: Twenty-five mesial roots of molars were used and had their crowns cut at the cemento-enamel junction. The actual measure of each root canal was performed and then the samples were embedded into a mixture of alginate, used as a conducting medium, where electronic measurements were taken with apex locator before and after preflaring of the canals with Gates-Glidden drills in descending order (#4, #3, #2). Measurements obtained by electronic method were then compared with the actual measurement of the root canal. The results were tabulated and submitted to the Student t test. Results: The results show that there was no statistical significance (p<0.05) between the readings before and after preflaring. Readings closer to the foraminal ending occurred in the group after preflaring with Gates Glidden. Conclusion: It was concluded that preflaring with Gates Glidden drills were not able to influence significantly the accuracy of apex locator in determining the exact working length.