RESUMO

AIM: To evaluate the behaviour of the XP-Endo Finisher and the variation in the intracanal temperature of the irrigant at rest and when activated over time. METHODOLOGY: Differential scanning calorimetry (DSC) determined the transformation temperatures of XP-Endo Finisher instruments. A digital thermocouple was used to measure the temperature of the irrigant inside the pulp chamber. Two measurements were performed for each tooth (n = 12): with the irrigant at rest and during XP-Endo agitation for 60 s to observe the temperature evolution. The data were statistically analysed using a t-test with a confidence level of 95%. RESULTS: DSC results suggested that the XP-Endo Finisher had a mixed R-phase and austenitic structure at room temperature. The temperature values at predetermined time points (0, 10, 40, 70, 120 and 240 s) were measured, and no statistical difference was observed between the values of the resting and activated solutions at any of the selected points (p > .05). For the protocol performed with the XP-Endo file, the mean irrigant temperature observed at instrument insertion inside the root canal was 28.65°C. After 60 s of agitation, the temperature was 34.02°C. The solution temperature stabilized inside the canal only after 211 s at 35.5°C. The mean maximum irrigation solution temperature recorded inside the canal was 35.5°C without agitation and after XP-endo agitation (p > .05). CONCLUSIONS: Although the XP-Endo Finisher system does not promote heating of the irrigation solution, file expansion responsible for improved instrument cleaning starts at a temperature below the expected value.

RESUMO

This ex vivo study assessed the effectiveness of two activation modes to increase the intracanal temperature of 5.25% NaOCl solution and the time for a preheated-irrigant to return to its initial temperature. Ten single-rooted extracted human teeth were used. Thermocouples were adapted to the root surface and the temperature was registered following two activation modes: ultrasound (US) and thermal. Furthermore, a preheated-solution (45°C/60°C) was flushed into root canal to test the time needed to return to its initial temperature. Data were analysed using two-way ANOVA and Tukey's post-hoc tests (P = 0.05). Statistical analysis showed differences between the activation modes. US and thermal activation increased from 37 to 40.4°C and to 62.8°C respectively in 60 s. Time for preheated-irrigant to return to its initial temperature was longer for 60°C. Preheating irrigant at 60°C and using thermal activation to keep it warm may represent a further step of the irrigation protocol.

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RESUMO

Técnicas de agitação da solução irrigadora melhoram a eficácia da limpeza apical através do aumento do fluxo de fluidos, potencializando a desinfecção do canal radicular. A irrigação ultrassônica passiva (PUI) é a técnica mais utilizada e promove, além de uma melhor limpeza, o aumento da temperatura do hipoclorito de sódio (NaOCl). Já o sistema XP-endo Finisher, tipo especial de instrumento rotatório de NiTi tratado termicamente, tem sua capacidade de alcance e eficácia aumentada através da alteração na sua conformação. Esta, ocorre devido à tranformação reversa da martensita quando o instrumento entra em contato com temperatura corporal no interior do canal radicular. O objetivo deste estudo foi avaliar a variação da temperatura da solução irrigadora no interior da câmara pulpar em três situações clínicas: em repouso e após agitação mecânica com o sistema XP-endo Finisher e PUI. As temperaturas de transformação dos instrumentos XP-Endo Finisher foram determinadas por DSC. Um Termopar digital foi usado para mensurar a temperatura do irrigante, dentro da câmara pulpar. Três mensurações foram realizadas em cada dente (n = 12): com a solução irrigadora em repouso, durante a agitação com XPEndo Finisher e durante o uso de PUI, ambos por 60 segundos, observando a evolução da temperatura por 325 segundos. Os dados foram analisados estatisticamente pelo teste t-student, com nível de confiança de 95%. Os resultados do DSC sugeriram que o instrumento XP-endo Finisher à temperatura ambiente apresenta uma estrutura mista, de austenita e fase R. Para o protocolo realizado com a lima XP-Endo, a temperatura média observada no momento da inserção do instrumento no interior do canal radicular foi de 28,7ºC. Após 60 segundos de agitação a temperatura atingiu 34°C. A estabilização da temperatura da solução dentro do canal a 35,5°C foi observada somente após 211 segundos. A temperatura média máxima da solução irrigadora registrada no interior do canal foi de 35,5°C com o irrigante em repouso e após agitação com XP-endo (p> 0,05). Para o protocolo realizado com PUI após 30 segundos de ativação da solução irrigadora a temperatura do NaOCl atingiu 33,3°C e após 60 segundos 37,8ºC, um aumento de aproximadamente 10°C na temperatura do irrigante foi observado. O sistema XP-endo Finisher não promove o aquecimento da solução irrigadora, mas a expansão do instrumento, que é responsável pela melhor capacidade de limpeza desse sistema, ocorrerá e começará em uma temperatura abaixo da esperada. O protocolo de agitação por 60 segundos com PUI, pode ser considerado uma técnica segura que, além dos benefícios descritos na literatura de aumentar a dinâmica do fluxo de fluidos, não promove um superaquecimento que poderia causar danos aos tecidos periodontais.

Irrigation solution agitation techniques improve the efficacy of apical cleaning by increasing the fluids flow, potentiating disinfection of the root canal. Passive ultrasonic irrigation (PUI) is the most used technique and promotes, besides a better cleaning, the increase of sodium hypochlorite (NaOCl) temperature. The XP-endo Finisher system, a special type of thermally treated NiTi rotary instrument, has its capacity to reach and increase efficiency due to a change in its conformation. This, occurs due to the reverse transformation of martensite when the instrument comes in contact with body temperature inside the root canal. The aim of this study was to evaluate the temperature variation of the irrigation solution inside the pulp chamber in three clinical situations: at resting and after mechanical agitation with the XP-endo Finisher system and PUI. Transformation temperatures of XP-Endo Finisher instruments were determined by DSC. A digital thermocouple was used to measure the irrigant temperature, inside the pulp chamber. Three measurements were performed in each teeth (n = 12): with irrigant at resting, during agitation with XP-Endo Finisher and during the use of PUI, both for 60 seconds, observing the temperature evolution. Data were statistically analyzed using t-student test, with a confidence level of 95%. DSC results suggested that XP-Endo finisher at room temperature will be in a mixed R-phase and austenitic structure. For the protocol performed with the XP-Endo file, the mean temperature observed at the time of instrument insertion inside the root canal was 28,7ºC. After 60 seconds of agitation temperature reached 34°C. The stabilization of the solution temperature inside the canal at 35.5°C was observed only after 211 seconds. The mean maximum irrigation solution temperature recorded inside the canal was 35.5°C with the irrigant at resting and after XP-endo agitation (p>0.05). For the protocol performed with PUI, after 30 seconds of irrigation solution activation the temperature of NaOCl reached 33.3°C and after 60 seconds 37.8°C, an increase of approximately 10°C in the irrigant temperature was observed. The XP-endo Finisher system does not promote heating of the irrigation solution, but the file expansion which is responsible for the instruments better cleaning ability will occur and it starts in a temperature under the expected. The 60 seconds PUI agitation protocol, can be considered a safe technique that besides the benefits described in the literature of increasing fluid flow dynamics, do not promote an overheating that could cause damage to periodontal organic tissues.

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