Scanning electron microscopy of root canal walls after removing the smear layer

Stomatološki Glasnik Srbije 01/2003;
Source: DOAJ

ABSTRACT The purpose of this study was to investigate ultrastructurally the effect of smear layer removal by applying different root canal irrigances: 3% HO2, 4% NaOCl and 15% Na-EDTA (in combination with 3% HO2, 4% NaOCl) and establish the appearance of root canal dentine surface after treatment with 15% Na-EDTA for different time periods(1 min and 5 min) using additional irrigant 3% HOor 4% NaOCl. 22 22 Teeth with single and double canals extracted for orthodontic reasons, were used in this study. After instrumentation, coronal and apical parts were removed. Middle parts were cut longitudinally into two equal segments. The specimens were grouped and treated: with HO2, NaOCl, and with combination of Na-EDTA+ HO2 and Na-EDTA+NaOCl where the irrigation with 2 Na-EDTA lasted 1 or 5 minutes. Control segments were enlarged and irrigated with distillate water to obtain the smear layer. The results obtained showed that irrigation with HOand NaOCl did 22 not remove the smear layer, one-minute application of 15% Na-EDTA followed by 4% NaOCl showed that the smear layer was completely removed. Using of 3% HOafter Na-EDTA over the same period of time obtained 22 less "clear" surfaces. Five-minute application of Na-EDTA caused excessive peritubular and intertubular dentinal erosion. It is concluded that for effective removal of smear layer with Na- EDTA, this procedure should not last longer than 1 minute and should be followed by NaOCl.

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    ABSTRACT: The purpose of the present scanning electron microscopic study was to investigate the efficacy of a combination of EDTA, NaOCl, and surface-active irrigating solutions during and after root canal preparation with ProFile nickel-titanium rotary instruments. Thirty canals were divided into three groups, instrumented and irrigated as follows: 5% NaOCl and a final flush with 17% EDTA were used for group A; group B specimens were irrigated using 17% EDTA, followed 15 s later by 1% TRITON X-100 (tensioactive agent) and then by 5% NaOCl; and group C specimens were irrigated with the same combination, but once shaping procedures were completed the irrigating sequence was repeated three times. After scanning electron microscopic evaluation, group C specimens exhibited the most effective debridement of the root canals. Results showed that tensioactive agent contributed to enhanced debridement. Cleaning was significantly improved once shaping procedures were completed.
    Journal of Endodontics 01/2000; 25(12):800-3. · 2.79 Impact Factor
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    ABSTRACT: Debris and smear layer were evaluated in canals prepared with either Lightspeed (LS) or ProFile (PF) rotary instruments. Irrigants used were tap water (group A) or alternating 5.25% NaOCl and 17% EDTA (group B). Apical stops were prepared to size 52.5 in the LS and to size 6 (approximately ISO size 36) in the PF techniques. The roots were split longitudinally and examined at apical, middle and coronal levels for debris and the smear layer using a 5-step scale. Using only water, mean debris scores were similar for LS and PF. In contrast, with EDTA/NaOCl, LS- and PF-prepared canals had similar debris scores at the apical and coronal levels, but there was a significant difference at the middle level. Mean smear layer scores were similar in LS- and PF-shaped canals when water was the sole irrigant. In contrast, with NaOCl and EDTA, mean smear layer scores were significantly different at the apical and middle levels, but not at the coronal level. Neither technique was superior in removing debris, but larger canal preparations obtained in this study with LS instruments enabled a more effective removal of the smear layer in the EDTA-NaOCl group.
    Journal of Endodontics 02/2000; 26(1):6-10. · 2.79 Impact Factor
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    ABSTRACT: When the root canals are instrumented during endodontic therapy, a layer of material composed of dentine, remnants of pulp tissue and odontoblastic processes, and sometimes bacteria, is always formed on the canal walls. This layer has been called the smear layer. It has an amorphous, irregular and granular appearance under the scanning electron microscope. The advantages and disadvantages of the presence of smear layer, and whether it should be removed or not from the instrumented root canals, are still controversial. It has been shown that this layer is not a complete barrier to bacteria and it delays but does not abolish the action of endodontic disinfectants. Endodontic smear layer also acts as a physical barrier interfering with adhesion and penetration of sealers into dentinal tubules. In turn, it may affect the sealing efficiency of root canal obturation. When it is not removed, the durability of the apical and coronal seal should be evaluated over a long period. If smear layer is to be removed, EDTA and NaOCl solutions have been shown to be effective, among various irrigation solutions and techniques, including ultrasonics, that have been tested. Once this layer is removed, it should be borne in mind that there is a risk of reinfecting dentinal tubules if the seal fails. Further studies are needed to establish the clinical importance of the absence or presence of smear layer.
    International Endodontic Journal 06/1995; 28(3):141-8. · 2.27 Impact Factor


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