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PubMed2005

Effects on smear layer and debris removal with varying volumes of 17% REDTA after rotary instrumentation.

The purpose of this study was to quantify the volume of 17% ethylene diamine tetra-acetic acid (EDTA) needed to efficiently remove the smear layer after rotary instrumentation, and to determine if additional irrigation has any effect on debris removal. Forty single canal teeth were instrumented with ProFile GT rotary instruments. Experimental groups were irrigated with 1, 3, or 10 ml of 17% EDTA for 1 min, followed by a final rinse with 3 ml of 5.25% sodium hypochlorite (NaOCl). Samples were scored for debris remaining and examined under SEM to determine quality of smear layer removal. There were no significant differences among groups when comparing either debris remaining or quality of smear layer removal. EDTA irrigation volume greater than 1 ml did not improve debris removal. Efficient removal of the smear layer was accomplished with a final rinse of 1 ml of 17% EDTA for 1 min, followed by 3 ml of 5.25% NaOCl.

Analysis of Variance↗
PubMed2000

Smear layer removal by EGTA.

The purpose of this study was to compare the effects of ethylene glycol-bis (beta-aminoethyl ether)-N,N,N', N'-tetraacetic acid (EGTA) and EDTA on removal of the smear layer by using scanning electron microscopy. Fifteen single-rooted teeth were instrumented to size 60. Three teeth served as the control group, and the remaining teeth were assigned into two groups. After instrumentation, root canals of the first group were irrigated with 10 ml of 17% EDTA, and the second group was irrigated with 10 ml of 17% EGTA for 2 min. Both were then irrigated with 10 ml of 5% NaOCl. The teeth in the control group were irrigated with only 10 ml of 5% NaOCl. Then the specimens were sectioned longitudinally and processed for scanning electron microscopy. The results showed that the smear layer was completely removed by EDTA, but it caused erosion of the tubuli. EGTA was somewhat effective in removing the smear layer without inducing erosion. Our results suggest that EGTA is an alternative chelator for removing the smear layer.

Chelating Agents↗
PubMed1993

Effects of Nd:YAG laser radiation on removal of a root surface smear layer after root planing: a scanning electron microscopic study.

A scanning electron microscopy (SEM) study was conducted to evaluate the effects of Nd:YAG laser radiation on removal of a root surface smear layer after root planing in comparison with citric acid treatment. The experimental materials were 15 human teeth affected by severe periodontal disease, which were extracted because of a hopeless prognosis. The teeth had at least 5 mm of attachment loss on the proximal surface tested. After removing all visible calculus using an ultrasonic scaler, each proximal surface was vigorously scaled and root planed with a Gracey curet. Thirty specimens were cut from the root-planed proximal surfaces and assigned randomly to one of two groups: Group A (25 specimens) was divided into 5 subgroups and irradiated with a Nd:YAG laser, using non-contact delivery (3 mm beam diameter, distance from the tip to the specimen 5 cm), at a measured power of 20 W for 0.3, 0.5, 1.0, 2.0, or 3.0 seconds corresponding to energy densities of 84.93, 141.54, 283.09, 566.17, or 849.26 J/cm2; Group B (5 specimens) was not irradiated, but treated for 3 minutes with saturated citric acid (pH 1). The center of each specimen in Group A was used as the experimental area (Exp A) treated by laser irradiation and the peripheral area of the specimen served as a control (Cont A). In Group B, one half of the specimen was used as the experimental area (Exp B) treated by citric acid and the other half served as a control (Cont B). The specimens were then fixed and examined by SEM. The surface of the root-planed specimens (Cont A and B) was irregular, corresponding to the presence of a smear layer, and had an amorphous appearance. Both root surfaces of Exp A and B exhibited clear orifices of dentinal tubules and intertubular dentin without a smear layer. Although the root surface of Exp A showed clear orifices of dentinal tubules with a flat morphology, the root surface of Exp B showed widened funnel-shaped dentinal tubule orifices with a fibrillar, mat-like morphology. The present results indicate that Nd:YAG radiation effectively removes the smear layer, uncovers dentinal tubules, and exposes collagen fibers on the root surface without widening the orifices of dentinal tubules after root planing.

Aluminum Silicates↗
PubMed2002

Influence of smear layer pretreatments on bond strength to dentin.

PURPOSE: To evaluate the tensile bond strength of two self-etching adhesive systems and one one-bottle system applied on dentin surfaces after different smear layer treatments. MATERIALS AND METHODS: The crowns of 36 extracted third molars were transversally sectioned with a diamond saw to expose dentin. Flat dentin surfaces were abraded wet with 600-grit SiC paper and randomly assigned to 12 groups, according to three adhesive systems--Prime & Bond NT (PB), Clearfil Mega Bond (CMB) and Etch & Prime 3.0 (EP)--and four dentin surface treatments: direct application over smear layer (no treatment), sandblasting with 50 microm Al2O3 for 10 s, etching with 36% phosphoric acid for 15 s, or conditioning with 0.5 M EDTA for 2 min. Composite "crowns" (6.0 mm high) were incrementally built on the bonded surfaces and teeth were stored in distilled water at 37 degrees C. Teeth were vertically, serially sectioned in both x and y directions to obtain bonded specimens of approximately 0.8 mm2 cross-sectional area. Each specimen was tested in tension in a universal testing machine at 0.5 mm/min. RESULTS: Overall microtensile bond strength (MPa) was 40.43 +/- 7.63 for PB, 27.03 +/- 8.40 for CMB, and 14.73 +/- 3.91 for EP. Mean bond strength for PB was significantly higher than self-etching systems. No significant differences were observed among smear layer treatments within the same dentin adhesive. CONCLUSION: Bond strength values were significantly different according to the adhesive system used. Different smear layer treatments prior to bonding did not affect tensile bond strength within the same bonding agent.

Acid Etching, Dental↗
PubMed2005

[The influence of smear layer and different sealers on apical microleakage of root canals obturated with Ultrafil-3D system].

PURPOSE: To evaluate the sealing properties of Ultrafil-3D system with three different root canal sealers in absence or presence of smear layer. METHODS: 64 straight single-root anterior teeth were selected and root canals were instrumented. 60 teeth were divided into two groups with or without smear layer. Each group was then divided into three subgroups, three different sealers (AH-plus, Roekoseal, CRCS) were applied in each subgroup when the root canals were obturated with Ultrafil-3D system (using Firm set gutta-percha). Other 4 teeth were used as control. After dyed in 2% methyl blue for 5 days, all teeth were longitudinally split from mesiodistal surface into two parts. The linear length of dye was measured for apical microleakage. SAS6.04 software was used for statistical analysis. RESULTS: (1) The linear dye penetration was significantly higher in group A (CRCS) compared with that in group B (AH-plus) and in group C (Roekoseal) (P<0.05). (2) Whether the smear layer was absent or present, the apical microleakage had no significant difference when using gutta-percha of Ultrafil-3D system with the same sealer (P>0.05). CONCLUSION: Root-canal obturation with Ultrafil-3D gutta-percha can obtain better sealing ability when AH-plus or Roekoseal is applied as sealer. Removing the smear layer can not significantly reduce the apical microleakage.

Dental Leakage↗
PubMed1996

Smear layer instability caused by hemostatic agents.

The effect of hemostatic agents, other than a 15.5% Fe2(SO4)3 solution, on prepared tooth structure is unknown. The purpose of this study was to (1) compare the effect of six commonly used hemostatic solutions and two nondental astringents on the dentinal smear layer and (2) determine whether different responses caused by product and/or time could be established. Standardized dentinal smear layers were exposed to eight astringent solutions for 30, 120, and 300 seconds (n = 6). A total of 144 SEM photographs at x2400 magnification were ranked according to predetermined criteria for five categories of smear layer removal and etching of underlying tooth structure. There were significant differences (p < 0.001) caused by the solution, exposure time, and their interaction. Greatest smear layer removal was observed with 21.3% AlCl3-6 hydrate, 8% racemic epinephrine HCl, and 15.5% Fe2(SO4)3 solutions at longer exposures. These caused significantly more removal than did almost pH neutral tetrahydrozoline or oxymetazoline (p < 0.05).

Acid Etching, Dental↗
PubMed1992

Evaluation of smear layers on serial sections of human dentin by means of electrochemical impedance measurements.

The alternating current impedance characteristics of a uni-directional porous glass membrane and serial sections of dentin from unerupted human third permanent molars (with and without smear layers) were measured. The membrane was equilibrated at 20 +/- 1 degrees C in a range of concentrations of unbuffered KCl, and the tooth sections were equilibrated in 0.1 mmol/L unbuffered KCl. Each section's impedance was measured for a 50-mV (rms) alternating potential difference applied over 1 Hz to 65 kHz. By means of complex non-linear least-squares regression analysis, the dc resistance of each specimen was determined. Scanning electron microscopy and subsequent image analysis enabled the cross-sectional area of the pores in the membrane and dentin tubule surface-openings to be measured. The results showed that the measured cross-sectional area of pores in the membrane was in good agreement with that calculated from the measured dc resistance and solution resistivity over the range of electrolyte concentrations. In dentin, the presence of smear layers on the cut surfaces increased the measured resistance. The resistance of the smear layer varied, suggesting that its thickness changed across the surface of the dentin. This was superimposed on regional variations in resistance of smear-free dentin which were found to be related to alterations in the number of tubules present and their cross-sectional area. The resistivities of the dentin tubule contents and smear layer material were generally lower than that of the hydrating electrolyte. It is postulated that this could be due to ions from partial dissolution of the mineral in the dentin.

Dentin↗
PubMed1996

[The effect of Kaviner and the smear layer on dentin permeability of permanent teeth in children].

The dentin permeability is defined as a moving of fluid, of chemical substances and microbial products as well through the dentin. The clinical protection of children permanent teeth in other words the protection of pulp-dentin complex after their preparation makes a big problem into the restorative stomatology. Caviner is one of the newer means which is used in the protection of pulp-dentin complex which represents the components of powder dispersing within the ethyl-acetate mixture of polystirol. The important variable in this study is the presence or absence of smearing layer which has the important influence onto the dentin permeability. In order to confirm the Caviner and smearing layer working onto the dentin permeability of the children permanent teeth in vitro experiment was designed. We used for it the dentin disks made of the intact first premolar, extracted because of orthodontic reasons at the ten years old children. They were put into the split chamber which represents a part of apparatus made at our Faculty, which is, in fact, a modified apparatus which was formed by prof. D.H. Pashley (Georgia, USA), and it is used for measuring of dentin permeability with the help of hydraulic conductance (Lp) of dentin. The dentin permeability is expressed by the hydraulic conductance term, but the measures are still expressed as the Lp percentage maximum because of better survey of results. Comparing the obtained results with the other authors results we have come to the similar conclusions, and that is in fact, that the smearing layer significantly reduces the dentin permeability, and that the Caviner, as the other layners, reduces the dentin permeability. If we compare the reduction of dentin permeability at the dentin covered with the smearing layer and with the Caviner, it has been noticed that the smearing layer reduces more significantly. It should be accented that the Caviner reduces the dentin permeability less than the most earlier researched means for the protection of pulp-dentin complex.

Acetates↗
PubMed2006

The effect of German chamomile (Marticaria recutita L.) extract and tea tree (Melaleuca alternifolia L.) oil used as irrigants on removal of smear layer: a scanning electron microscopy study.

AIM: To compare the cleaning effectiveness of chamomile hydroalcoholic extract and tea tree oil to 2.5% sodium hypochlorite (NaOCl) solution as an intracanal irrigant for the removal of the smear layer. METHODOLOGY: Forty extracted, single-rooted, mature, permanent, human teeth were allocated at random into one of three experimental groups of ten teeth and two control groups of five teeth. For each tooth, the pulp chamber was accessed and the canal prepared using K-type files and Gates-Glidden burs, using a step-back technique; the apical stop was prepared to a size 30. Each canal was subsequently irrigated with one of the following solutions: distilled water (as a negative control), 2.5% NaOCl + 17% ethylenediamine tetraacetic acid (EDTA) (as a positive control), chamomile or tea tree oil or 2.5% NaOCl. Each tooth was split longitudinally and prepared for examination by scanning electron microscopy (SEM). The quantity of smear layer remaining on the three levels of each canal (coronal, middle and apical) was examined using magnifications of 2000 and 5000x. The data were analysed using nonparametric Kruskal-Wallis and Mann-Whitney U-tests. RESULTS: The most effective removal of smear layer occurred with the use of NaOCl with a final rinse of 17% EDTA (negative control) followed by the use of a chamomile extract. Chamomile extract was found to be significantly more effective than distilled water and tea tree oil (P < 0.008). The use of a 2.5% NaOCl solution alone, without EDTA and that of tea tree oil, was found to have only minor effects. There was no statistical difference between distilled water, 2.5% NaOCl and tea tree oil. CONCLUSIONS: The efficacy of chamomile to remove smear layer was superior to NaOCl alone but less than NaOCl combined with EDTA.

Dentin↗
PubMed2004

Smear layer removal capacity of disinfectant solutions used with and without EDTA for the irrigation of canals: a SEM study.

The purpose of this study was to carry out a scanning electron microscopic (SEM) analysis of the cleaning qualities and smear layer removal from root canal walls, instrumented and irrigated with 2.5% NaOCl, 2.0% chlorhexidine and saline solutions. Fifty extracted teeth were used in this study. All teeth were radiographed to determine the existence of a single canal. The crowns were cut at the cervical limit and the root canals were instrumented with K-type files up to size 45. During root canal preparation, irrigations were made with the different solutions being evaluated: Group 1: 2.5% NaOCl (10 roots); Group 2: 2.5% NaOCl and 17% EDTA for 2 minute (10 roots); Group 3: 2.0% chlorhexidine (10 roots); Group 4: 2.0% chlorhexidine and 17% EDTA for 2 minutes (10 roots); Group 5: saline solution (5 roots); Group 6: saline solution and 17% EDTA for 2 minutes (5 roots). After instrumentation, the canals were irrigated with each one of the solutions and the roots were cut in the buccolingual direction for SEM analysis, at the cervical, middle and apical thirds, to ascertain the presence or absence of smear layer and debris. SEM analysis was performed by three calibrated examiners and scores were submitted to Kruskal-Wallis test at the significance level of p = 5%. Results showed that the use of 17% EDTA decreased the smear layer significantly (p < 0.05) for all evaluated solutions in all thirds. When EDTA was not used, a significantly higher quantity of smear layer on the apical third was observed only in the NaOCl groups. The use of 17% EDTA was significant for debris removal except for the chlorhexidine groups. The following conclusion could be drawn: the use of 17% EDTA was necessary to enhance cleanness of the root canals.

Analysis of Variance↗
PubMed2005

The ability of fruit teas to remove the smear layer: an in vitro study of tubule patency.

OBJECTIVES: Fruit teas are know to have an erosive effect on enamel, but the effects on dentine are unknown. Lesions of dentine hypersensitivity have numerous patent dentinal tubules and the aim of this paper was to examine the ability of various fruit teas to remove the smear layer. METHODS: The erosive potential of a variety of fruit teas was assessed in the laboratory by measuring their pH and neutralisable acidity. Smeared dentine specimens were prepared from extracted teeth and the ability of each tea to remove the smear layer was assessed by measuring the diameter and area of the opened tubules and counting the number of patent tubules seen in a unit area using scanning electron microscopy. A 0.2% citric acid solution was used as a positive control. RESULTS: The pH of the fruit teas ranged from 2.98 to 3.95 and the neutralisable acidity ranged from 10.63 to 33.0 ml of 0.1 M NaOH. All the fruit teas tested were able to remove the smear layer. The mean diameter of the tubules ranged from 0.61 to 1.14 microm and the mean area ranged from 0.31 to 1.03 microm2. The number of patent tubules per specimen ranged from 13 to 121. CONCLUSION: All the fruit teas tested were found to be highly acidic and able to remove the smear layer.

Dental Enamel↗
PubMed1997

[Influence of smear layer and adhesive resin on the adaptation of amalgam restoration to cavity walls].

This in vitro study evaluated the effect of removing smear layer and applying adhesive on the marginal adaptation of amalgam fillings to cavity walls. Three groups were established, cavities in group 1 were exposed to 10% EDTA (pH7.4) for 1 minute to remove smear layer before amalgam condensation; cavities in group 2 were also subjected to EDTA, then Miradapt adhesive was applied on the walls, finally amalgam condensed into cavities before the adhesive set; cavities in group 3 received no special treatment before amalgam condensation. After thermocycling, all teeth were subjected to SEM and image analyser. Results showed: Space between restorations and tooth structure in group 1 was 6.31 microns, space in group 2 with adhesive was 3.49 microns and micromechanical interlocking was observed while space in control group was 14.22 microns. Difference among the three groups was statistical significant. It was indicated that removing smear layer and using adhesive resin significantly improved the adaptation of amalgam to cavity walls.

Composite Resins↗
PubMed2003

Efficacy of various concentrations of citric acid at different pH values for smear layer removal.

OBJECTIVE: The efficacy of various concentrations of citric acid at different pH values for the removal of the superficial smear layer from dentinal surfaces was examined through the use of scanning electron microscopy. Study design Fifty extracted teeth were irrigated with sodium hypochlorite (NaOCl) during instrumentation. Citric acid solutions at 50%, 25%, 10%, and 5% (wt/vol) concentrations were prepared. In addition, similar solutions of citric acid were buffered to pH 6. Citric acid solutions with original and buffered pH values were used as final rinses. Bidistilled water and NaOCl were used as controls. The data were analyzed by using nonparametric Kruskal-Wallis and Mann-Whitney U tests. RESULTS: Lower concentrations with lower pH values removed smear layer more efficiently than the ones with higher pH values (P <.05), whereas no significant differences for higher concentrations were detected between low and high pH values. However, more destruction of peritubular dentin was observed at higher concentrations with low pH values. CONCLUSION: Within the limits of this study, lower concentrations of citric acid with its original pH were found to be as effective as higher concentrations in the removal of superficial smear layer.

Buffers↗
PubMed1989

The effectiveness of different endodontic irrigation procedures on the removal of the smear layer: a scanning electron microscopic study.

To compare the effectiveness of different irrigation procedures on the removal of the smear layer, 40 curved canals were manually prepared in vitro under copious irrigation with 3 per cent NaOCl. Ten canals served as controls. The remaining 30 were equally distributed in three experimental groups and subsequently irrigated with the following: ultrasound with NaOCl; EDTA; ultrasound with EDTA. In the scanning electron microscope, the appearance of the smear layer was rated over the distribution of dentinal tubule openings for the coronal, middle and apical segments of the canals. Irrigation with NaOCl produced consistently smeared surfaces. Ultrasonic stirring of NaOCl removed the smear layer moderately, while EDTA produced almost smear-free surfaces. Ultrasound in association with EDTA did not enhance the dissolving capability of this chelating agent. A definite decline in the efficiency of the irrigation procedures was also observed along the apical part of the canals.

Dentin↗
PubMed2002

Scanning electron microscopic and energy dispersive spectrometric investigations on the effect of XeCl excimer laser on human dentin with smear layer.

The purpose of this study was to study the effect of XeCl excimer laser on smear layer covered dentine of extracted human teeth. Twenty-four freshly extracted human molar teeth were collected and randomly divided into one control group and three experimental groups of six teeth each (groups A-D). The teeth in the experimental groups were irradiated with XeCl 308-nm excimer laser at a fluence of 0.4 J cm-2 and a constant pulse repetition rate of 25 Hz. Group A was used as the control, while groups B, C and D were irradiated at different exposure times of 3, 5 and 7 s, respectively. Subsequently these teeth specimens were subjected to scanning electron microscopic (SEM) examination and energy dispersive X-ray (EDX) spectrometric analysis. The SEM examination revealed melting of the smear layer covered dentin to conceal the underlying dentinal tubules. At a longer exposure time (7 s), dentin melted to form large grains and this resulted in non-uniform closure of underlying dentinal tubules. Under the conditions of this study, it is concluded that the pulsed XeCl 308-nm excimer laser at a fluence of 0.4 J cm-2, with an exposure time of 5 s uniformly occluded exposed smear layer covered dentine with no conspicuous variation in chemical structure.

Calcium↗
PubMedDate not supplied

Efficacy of EDTA-T gel for smear layer removal at root surfaces.

OBJECTIVE: The purpose of this in vitro study was to investigate the efficacy of EDTA gel preparation, associated with texapon detergent (EDTA-T), for removing the smear layer at human root surfaces. METHOD AND MATERIALS: An experimental smear layer was produced by scaling using periodontal curettes, and the root surfaces were etched with the following concentrations of EDTA-T: 5%, 10%, 15%, 20%, 24%, and negative control (saline solution) for 1, 2, or 3 minutes using both passive and active methods. The surfaces were evaluated by scanning electron microscopy, and photomicrographs were evaluated in relation to smear removal. RESULTS: All EDTA-T groups were more effective than the control group (P < .0001). EDTA-T at 15% was more effective when applied by the passive method, although this difference was not observed for the active method. The active method was statistically better than the passive method (P < .0001). CONCLUSION: The etching of the root surface with EDTA-T gel by active application, independently of the other factors evaluated, was effective for smear layer removal.

Acid Etching, Dental↗
PubMed2003

Light and scanning electron microscopic evaluation of Glyde File Prep in smear layer removal.

AIM: To evaluate the effectiveness of Glyde File Prep used in conjunction with sodium hypochlorite irrigation in the removal of smear layer produced during root canal instrumentation. METHODOLOGY: Thirty-nine extracted human teeth with single root canals were used. Access cavities were prepared and the teeth divided into three groups of 13 teeth each. Each group was treated by one of the three different regimes of irrigation and conditioning during root canal instrumentation. Group A: 0.5 mL of 1% NaOCl irrigation after each file size with an additional final irrigation of 10 mL 1% NaOCl; group B: 0.5 mL of 1% NaOCl irrigation after each file size with an additional final irrigation of 10 mL 17% EDTA; group C: Glyde File Prep coated on each instrumentation file used in conjunction with 0.5 mL 1% NaOCl irrigation after each file size and an additional final irrigation of 10 mL 1% NaOCl. The teeth were then longitudinally grooved and sectioned. Root canal cleanliness was evaluated with the aid of a Nikon light microscope (x40 and x100) and scanning electron microscope (x1000 and x3000). The debris scores obtained at three canal regions were compared statistically within the same group and among different groups using repeated measurements of analysis of variance (anova) with Bonferroni adjustments and anova with posthoc Tukey HSD, respectively. RESULTS: The canals treated with EDTA and Glyde File Prep were significantly cleaner than those treated with NaOCl alone. The apical region of the root canals generally displayed more residual smear layer, but the difference was not significant. CONCLUSIONS: Used in conjunction with NaOCl irrigation, Glyde File Prep was effective in removing smear layer produced during root canal instrumentation.

Analysis of Variance↗
PubMed1992

Effect of precurving endosonic files on the amount of debris and smear layer remaining in curved root canals.

Endosonic files are prone to constraint; this reduces their efficiency, particularly in the apical third and in curved root canals. Precurving the file may reduce constraint, thereby improving the file's ability to debride. This investigation was undertaken to compare both straight and precurved endosonic files as to debris and smear layer removal. Thirty-six curved root canals were randomly allocated into six groups. Each group was prepared using a step-down technique, then instrumented with either a straight or precurved endosonic file of size 15, 20, or 25. The tooth roots were split and examined under the scanning electron microscope. Blind examinations were made for debris and smear layer removal and evaluation scores were analyzed using a log linear approach. The root canals instrumented with the precurved files had a significantly lower debris score than those prepared with straight files. Precurving did not affect smear layer removal. In conclusion, precurving of files decreased the amount of debris but did not affect smear layer removal.

Dental Cavity Preparation↗