Avaliação in vitro da influência da lima patência na manutenção do comprimento de trabalho / In vitro evaluation of the influence of patency file in maintaining the working length

Objetivo: Este trabalho teve como objetivo avaliar a influência da lima patência na manutenção do comprimento de trabalho (CT) durante o preparo coroa-ápice, utilizando o sistema oscilatório em canais artificiais de acrílico. Material e método: Foram utilizados 30 cubos de acrílico: a) grupo 1 (n=10): sem a lima patência e preparo no CT (CT=16 mm); b) grupo 2 (n=10): com a lima patência K#10, comprimento de patência de 17 mm e preparo no CT; c) grupo 3 (n=10): sem a lima patência, uso de uma lima K#10 em 16 mm para recapitulação e preparo no CT. Água destilada foi utilizada como solução irrigadora. O resultado foi analisado estatisticamente pelos testes de Levene e Kruskal-Wallis (p≤0,05), pelos quais se tornou possível observar a perda do comprimento de trabalho após a instrumentação, em diferentes abordagens, em relação à lima patência. Resultado: Os resultados obtidos demonstraram que houve diferença estatisticamente significante entre os grupos 1 e 3 quando comparados ao grupo 2; entretanto, ao comparar-se o grupo 1 com o grupo 3, estes apresentaram semelhanças estatísticas. O grupo 2 foi o único que conservou o CT após a instrumentação em 16 mm, enquanto os grupos 1 e 3 apresentaram uma perda de até 2 mm do CT. Conclusão: Conclui-se que a lima patência em 1 mm além do CT mostrou-se eficaz na manutenção do seu comprimento durante o preparo do canal radicular.

Objective: This study aimed to evaluate the influence of patency file in maintaining the working lenght (WL) for the crown-down preparation using oscillating system in artificial canals of acrylic. Material and method: Thirty acrylic cubes were divided: a) Group 1 (n=10): without patency file and it were prepared in CT (CT=16 mm); b) Group 2 (n=10): with the patency #10 K-file, patency length of 17 mm and it were prepared in CT; and c) Group 3 (n=10): without patency file, using a #10 K-file in 16 mm for recapitulation and it were prepared in CT. Distilled water was used as irrigating solution. The results were statistically analyzed by the Levene and the Kruskal-Wallis test (p≤0.05), where it observed the loss of WL after instrumentation in different approaches to patency file. Result: The results showed a statistically significant difference between groups 1 and 3 compared to group 2, however the group 1 be compared in relation to these 3 showed statistical similarities. Group 2 was the one who saved the WL after instrumentation in 16 mm, while group 1 and 3 showed a loss of up to 2 mm WL. Conclusion: It was concluded that the patency file at 1 mm beyond the WL was effective in maintaining its length during root canal preparation.

Relationship between the size of patency file and apical extrusion of sodium hypochlorite.

Background: Sodium hypochlorite (NaOCl) is the most widely used endodontic irrigant because of its excellent antimicrobial, organic tissue dissolving, and lubricating properties. However, it is highly cytotoxic to the periapical tissues. Aim: This study evaluated in vitro the extrusion of 5.25% NaOCl through the apical foramina of mesiobuccal (MB) root canals of maxillary first molars in two experimental conditions: Before apical debridement and after apical debridement with different instrument sizes to ensure direct access to the apical foramen (apical patency). Materials and Methods: Coronal accesses were prepared in 17 teeth and the apical foramina of the distobuccal and palatal root canals were sealed. The teeth were held in acrylic receptacles with the roots turned upwards to reproduce their position in the maxillary dental arch. The receptacles were filled with a starch/KI solution (a reagent that changes its color to blue after contacting NaOCl) covering the roots. The experiment had two phases: P1: Irrigation of the MB canals with 5.25% NaOCl without previous establishment of apical patency; P2: Canal irrigation after use of size 10 K-file and size 15 Flexofile as patency files. Only specimens with no NaOCl extrusion in P1 were assigned to P2. NaOCl was delivered pressureless at the canal entrance. The moment that the starch/KI solution contacted NaOCl was captured on digital photographs. Results and Conclusions: There was no NaOCl extrusion in nine specimens in P1, but all of these teeth had irrigant extrusion in P2. The 5.25% NaOCl used as an endodontic irrigant showed great capacity to extrude beyond both intact and small-sized apical foramina of MB root canals of maxillary first molars.