Scanning electron microscopy investigation of canal cleaning after canal preparation with nickel titanium files

Abstract

Introduction. Root canal preparation is the most important phase of endodontic procedure and it consists of adequate canal space cleaning and shaping. In recent years, rotary instruments and techniques have gained importance because of the great efficacy, speed and safety of the preparation procedure. Objective. The aim of this research was to investigate the influence of different NiTi files on the canal wall cleaning quality, residual dentine debris and smear layer. Methods. The research was conducted on extracted human teeth in vitro conditions. Teeth were divided in 7 main groups depending on the kind of instruments used for root canal preparation: ProTaper, GT, ProFile, K-3, FlexMaster, hand ProTaper and hand GT. Root canal preparation was accomplished by crown-down technique. Prepared samples were assessed on scanning electron microscopy JEOL, JSM-6460 LV. The evaluation of dentine debris was done with 500x magnification, and the evaluation of smear layer with 1,000 times magnification. Quantitive assessment of dentine debris and smear layer was done according to the criteria of Hulsmann. Results. The least amount of debris and smear layer has been found in canals shaped with ProFile instruments, and the largest amount in canals shaped with FlexMaster instruments. Canal cleaning efficacy of hand GT and ProTaper files has been similar to cleaning efficacy of rotary NiTi files. Statistic analysis has shown a significant difference in amount of dentine debris and smear layer on the canal walls between sample groups shaped with different instruments. Conclusion. Completely clean canals have not been found in any tested group of instruments. The largest amount of debris and smear layer has been found in the apical third of all canals. The design and the type of endodontic instruments influence the efficacy of the canal cleaning.

Uvod. Preparacija kanala korena zuba je najvažnija faza u endodontskom postupku, a podrazumeva adekvatno čišćenje i oblikovanje kanalnog prostora. Mašinske tehnike preparacije i mašinski rotirajući instrumenti poslednjih godina dobijaju na značaju zbog brzine preparacije, efikasnosti obrade kanala korena i sigurnosti pri realizaciji ove faze endodontskog lečenja. Cilj rada. Cilj istraživanja je bio da se ispita uticaj različitih vrsta mašinskih i ručnih nikltitanijumskih (NiTi) instrumenata na kvalitet čišćenja zidova kanala korena zuba i analizira količina zaostalog debrisa i razmaznog sloja na zidovima nakon instrumentacije kanala. Metode rada. Istraživanje je izvedeno u uslovima in vitro na ekstrahovanim humanim zubima. Prema vrsti korišćenih NiTi instrumenata, zubi su podeljeni u sedam osnovnih grupa: ProTaper, GT, ProFile, K-3, FlexMaster, ručni ProTaper i ručni GT. Preparacija kanala korena zuba vršena je tehnikom crown-down. Pripremljeni uzorci posmatrani su na skening- elektronskom mikroskopu JEOL, JSM-6460 LV. Procena količine debrisa vršena je pri uveličanju od 500 puta, a razmaznog sloja pri uveličanju od 1000 puta. Za kvantitativnu procenu postojanja debrisa i razmaznog sloja na zidovima kanala korena zuba nakon instrumentacije i irigacije primenjeni su kriterijumi po Hilsmanu (Hülsmann) i saradnicima. Rezultati Najmanje debrisa i razmaznog sloja uočeno je nakon preparacije ProFile instrumentima, a najviše nakon preparacije FlexMaster instrumentima. Kvalitet čišćenja zidova kanala korena zuba ručnim GT i ProTaper instrumentima je vrlo sličan kvalitetu čišćenja nakon primene rotirajućih NiTi instrumenata. Analizom je utvrđeno da postoji statistički značajna razlika u količini zaostalog debrisa i razmaznog sloja na zidovima kanala korena zuba nakon instrumentacije različitim NiTi instrumentima. Zaključak. Nijedna vrsta mašinskih i ručnih NiTi instrumenata nije obezbedila potpuno čišćenje zidova kanala korena zuba. Najviše zaostalog debrisa i razmaznog sloja nađeno je u apeksnoj trećini kanala svih ispitivanih uzoraka zuba. Dizajn i vrsta endodontskih instrumenata utiču na efikasnost čišćenja kanala.