Evaluation of the smear layer removal effectiveness of EDTA using two techniques: an SEM study.

Obtaining the cleanest canal possible before obturation is one of the goals of endodontic treatment. The purpose of this study was to compare the smear layer removal capability of ethylenediamine tetra-acetic acid (EDTA) application with passive ultrasonic and cotton wrapped on reamer activation. Twelve extracted human teeth with single root canals were used for the study. They were conventionally hand instrumented using reamers and K files. The apical aspect of the canals was enlarged to a #40 file. The teeth were divided into 4 four groups, instrumented and irrigated as follows: Group-A EDTA agitated at the end of preparation with cotton wrapped on a reamer for 1 min; Group-B EDTA applied with ultrasonic agitation for 1 min; Group-C irrigated with EDTA+sodium hypochlorite (NaOCl) (negative control group); and Group-D irrigated with distilled water (positive control group). After scanning electron microscopic study at three different levels, smear layer and dentinal tubules were scored. Means were tested for significance using the Z test. When the techniques were compared, the cotton wrapped on reamer agitation method was as successful as the ultrasonic activation of the files. Although all groups had significantly higher smear layer scores at apical compared to coronal sections, no significant differences were recorded.

The effects of water and acetone-based dentin adhesives on apical microleakage.

In this study, the aim was to assess the in vitro apical microleakage of a resin-based sealer used with two different adhesives. Thirty nine freshly extracted maxillary incisors were used. The teeth were decoronated at the cemento-enamel junction with a water-cooled fissure bur. Chemo-mechanical debridement of the root canals was accomplished with the step-back technique. The smear layer was removed by 19% ethylenediamine tetra acetic acid (EDTA). The roots were then divided into three experimental groups of thirteen teeth in each. Specimens in group 1 were filled with gutta-percha, AH Plus sealer, and water-based adhesive system (Syntac Single Component). Group 2 specimens were filled with gutta-percha, AH Plus sealer, and acetone-based dentin adhesive (Prime & Bond NT ). Specimens of group 3 were filled with only gutta-percha and AH Plus sealer (no adhesive was applied). The teeth were immersed into 2% methylene blue solution. Apical sealing qualities were assessed by measuring the linear dye penetration with a stereomicroscope. Dentin tubule penetration was observed under scanning electron microscopy (SEM). Results showed no statistically significant difference between the materials used, however, the leakage in group 2 was less than group 1 and 3.

Influence of passive ultrasonic activation on the penetration depth of different sealers.

Correct use of instruments and irrigating solutions are major factors during chemo-mechanical preparation of root canals. Ultrasonically activated files and solutions are used for debridement of canals. In this study 42 single rooted anterior human teeth were used. The roots were divided into two groups. One group received an application of 17% ethylenediamine tetra acetic acid (EDTA) of 1 ml for 1 min using an ultrasonically energized file. The other group received an application of 17% EDTA of 1 ml for 0.5 min using an ultrasonically energized file. The groups were divided again into two subgroups. The roots were filled with a resin based sealer, AH26 and a glass ionomer sealer--Endion with lateral condensation technique. The roots were separated into two halves. The specimens were viewed through a scanning electron microscope (SEM). Statistical differences between the groups and regions were analyzed with Variance and Duncan tests. Under the conditions of this study, it can be said that ultrasonically activated irrigation did not reduce the smear layer effectively at 1 min and 0.5 min time intervals. According to this result, no difference was observed between the penetration of sealers.