The efficacy of rotary and manual instruments in root canal debridement
MetadataShow full item record
It has been shown that the use of both manual and rotary instruments result in the formation of a smear layer and debris during root canal treatment. The amount that is formed depends on the type of instrumentation used as well as the force applied. The purposes of this study were to use the scanning electron microscope to compare the cleanliness of the root canal walls following rotary and manual debridement methods, to assess the transportation of the apical part of the root canal orifice when using different instrumentation techniques. Endodontic treatment was performed on extracted maxillary central incisors following extirpation and debridement using the Protaper® nickel titanium files and K-files. The teeth were randomly divided into three groups. Endodontic therapy performed simulated the clinical procedures, in which the teeth were extirpated using a barbed broach to remove the necrotic pulp. Pre-operative periapical radiographs were used to determine the working length. Root canals were debrided using the two filing methods, with copious irrigation using Sodium hypochlorite solution in a disposable syringe with a 27 gauge needle. A follow up radiograph with a master apical file in position was used to verify complete debridement in the apical third of the anal. The teeth were then sectioned vertically using a diamond bur to create an initial groove and then split apart using a flat plastic instrument to separate the sections and to avoid contamination of the sections. These sectioned portions were then studied under a scanning electron microscope. The mear layer as well as the amount of debris was evaluated. The assessment of residual debris and smear layer formed, were assigned numbers and tabulated. All three areas of the root canal were compared against each other. The sectioned apical third of the root canal was also studied for the presence or absence of apical transportation. From the present study, it was found that both the nickel-titanium rotary files and stainless steel hand files produced some smear layer and there was some residual debris left in uninstrumented areas of the root canal. However, it was shown that there was more smear layer formation when using nickel-titanium rotary files compared to that formed using hand files. When assessed for the presence of apical transportation, it was found that both types of instrumentation resulted in some degree of transportation, however, with rotary files, the canals remained largely centralized with transportation clearly visible in hand instrumented canals.