Effects of different irrigation solutions on root dentine microhardness,smear layer removal and erosion

This study aimed to compare the effects of different irrigants on root dentine microhardness, erosion and smear layer removal. A total of 72 root dentine slices were divided into six groups, according to the final irrigants used: Group 1: 17% ethylenediamine tetra‐acetic acid (EDTA) + 2.5% NaOCl, Group 2: 7% maleic acid (MA) + 2.5% sodium hypochloride (NaOCl), Group 3: 1.3% NaOCl + mixture of tetracycline, acid and detergent (MTAD), Group 4: Smear Clear + 2.5% NaOCl, Group 5: 5% NaOCl, Group 6: saline. Vickers microhardness values were measured before and after treatment. In total, 42 root‐halves were prepared for scanning electron microscope to evaluate the amount of smear and erosion in the coronal, middle and apical thirds. Data were analysed using two‐way anova , Duncan and two‐proportion z‐tests. Maleic acid showed the greatest reduction in dentine microhardness (P < 0.05), followed by EDTA and MTAD. EDTA, maleic acid, MTAD and Smear Clear removed smear layer efficiently in the coronal and middle thirds of root canal. However, in the apical region, maleic acid showed more efficient removal of the smear layer than the other irrigants (P < 0.05).     

Activation of ethylenediaminetetraacetic acid by a 940 nm diode laser for enhanced removal of smear layer

Laser enhancement of ethylenediaminetetraacetic acid with cetrimide (EDTAC) has previously been shown to increase removal of smear layer, for middle‐infrared erbium lasers. This study evaluated the efficiency of EDTAC activation using a near‐infrared‐pulsed 940 nm laser delivered by plain fibre tips into 15% EDTAC or 3% hydrogen peroxide. Root canals in 4 groups of 10 single roots were prepared using rotary files, with controls for the presence and absence of smear layer. After laser treatment (80 mJ pulse^?1, 50 Hz, 6 cycles of 10 s), roots were split and the apical, middle and coronal thirds of the canal were examined using scanning electron microscopy, with the area of dentine tubules determined by a validated quantitative image analysis method. Lasing EDTAC considerably improved smear layer removal, while lasing into peroxide gave minimal smear layer removal. The laser protocol used was more effective for smear layer removal than the ‘gold standard’ protocol using EDTAC with sodium hypochlorite (NaOCl). In addition, lasers may also provide a benefit through photothermal disinfection. Further research is needed to optimise irrigant activation protocols using near‐infrared diode lasers of other wavelengths.     

Does endodontic post space irrigation affect smear layer removal and bonding effectiveness?

The effect of different post space irrigants on smear layer removal and dentin bond strength was evaluated. Sixty-six extracted sound maxillary central incisors were endodontically treated. After post space preparation, the teeth were assigned to three groups of 22 teeth each. The teeth of these three groups were irrigated for 1 min with 17% ethylenediaminetetracetic acid (EDTA) (group 1), 5.25% sodium hypochlorite (NaOCl) (group 2), or 0.9% sodium chloride (NaCl) (group 3). In each group, eight specimens were split longitudinally for smear layer evaluation, and the other fourteen specimens were filled with a self-etching adhesive system (Panavia F). Four of 14 specimens of each group were prepared for evaluation of the resin–dentin interdiffusion zone (RDIZ) and resin tags, and the other 10 specimens were serially sectioned for push-out test analysis. Smear layer removal and bond strength were affected by different post space irrigants. EDTA removed the smear layer extremely effectively and, as a result, improved the bond strength at each region (apical, middle, and coronal) of the roots. Resin tag formation and the RDIZ were also affected by different irrigants and in accordance with bond strength. Therefore, removal of the smear layer use a self-etching luting system plays an important role in bonding effectiveness.     

The Effect of Endodontic Irrigants on the Microtensile Bond Strength of Dentin Adhesives

IntroductionThe purpose of this study was to evaluate the microtensile bond strength of a total etch (XP-Bond) and a self-etch (Clearfil SE Bond) adhesive system to dentine surfaces treated using endodontic irrigants.MethodsTwenty-four freshly extracted third molars were used. After creating a smear layer on the coronal midthird portion of the crowns, the teeth were divided into three groups and surfaces were irrigated with distilled water, 5.25% NaOCl + 17% EDTA, and 1.3% NaOCl + BioPure MTAD, respectively. Each group was divided into two subgroups, and a self-etching adhesive and an etch-and-rinse adhesive were applied respectively. The teeth were restored with a composite material and sectioned to produce sticks for microtensile bond testing.ResultsThe microtensile bond strength of the MTAD + Clearfil SE group was found to be significantly lower than the microtensile bond strength of the distilled water + Clearfil SE Bond group and the NaOCl, EDTA, + Clearfil SE Bond group (p = 0.0001, p = 0.009).ConclusionsBecause of the significant reduction of Clearfil SE Bond to coronal dentine after MTAD application, an etch-and rinse adhesive such as XP-Bond may be preferred if this irrigant has been chosen during endodontic treatment.     

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.     

Tetracycline HCl solution as a root canal irrigant.

The effect of tetracycline hydrochloride as an endodontic irrigant on smear layer removal was examined by scanning electron microscopy and compared with bidistilled water, 2.5% sodium hypochlorite (NaOCl), and 50% citric acid in 20 extracted teeth. Five teeth, as a control, were irrigated with bidistilled water only in group 1. All the other groups were irrigated with NaOCI during instrumentation. The final rinses were NaOCl in group 2, citric acid in group 3, and 1% tetracycline hydrochloride in group 4. Scanning electron microscopic results and statistical analysis revealed that bidistilled water and NaOCl were ineffective in removing the smear layer, whereas citric acid and tetracycline hydrochloride were significantly more effective (p < 0.001). No statistically significant difference was detected between tetracycline hydrochloride and citric acid (p > 0.05). However tetracycline hydrochloride demineralized less peritubular dentin.     

The effectiveness of different acid irrigating solutions in root canal cleaning after hand and rotary instrumentation

The goal of this study was to evaluate the cleaning ability of three acid irrigating solutions after hand and rotary instrumentation. Eighty human teeth were randomly divided in eight groups. Four groups were prepared with hand instrumentation and other four with ProTaper. The irrigating solutions were 15% citric acid plus 2.5% NaOCl; 15% EDTA plus 2.5% NaOCl; 5% orthophosphoric acid plus 2.5% NaOCl; and 2.5% NaOCl alone as control. Canal walls were observed with scanning electron microscopy, and photomicrographs were taken in apical, middle, and coronal thirds. A scoring system for debris and smear layer was used. Acid solutions with 2.5% NaOCl were effective in the elimination of smear layer or debris, and no significant differences were showed in smear layer removal between techniques. However, 2.5% NaOCl did not remove smear layer or debris, and no significant differences in debris were observed between manual and rotary techniques.     

Comparison of the Efficacy of Maleic Acid and Ethylenediaminetetraacetic Acid in Smear Layer Removal from Instrumented Human Root Canal: A Scanning Electron Microscopic Study

IntroductionThe aim of this study was to assess, by scanning electron microscopic (SEM) analysis, the ability of 17% EDTA and 7% maleic acid in the removal of the smear layer from the human root canal system.MethodsEighty single-rooted human anterior teeth were subjected to standardized root canal instrumentation (step-back technique) and were irrigated with 2.5% NaOCl after each instrument. Based on the final irrigating solution used, samples were divided randomly into three groups: (1) the EDTA group: 17% EDTA+ 2.5% NaOCl (n = 30), (2) the maleic acid group: 7% maleic acid + 2.5% NaOCl (n = 30), and (3) the control group: 0.9% saline (n = 20). After final irrigation, teeth were prepared for SEM analysis to evaluate the cleaning of the coronal, middle, and apical thirds of radicular dentin by determining the presence or absence of smear layer. The data was statistically analyzed using the Kruskall-Wallis test.ResultsAt the coronal and middle thirds, there was no significant difference between EDTA and maleic acid. Both were equally efficient in the removal of smear layer. In the apical third, maleic acid showed significantly better smear layer removing ability than EDTA.ConclusionFinal irrigation with 7% maleic acid is more efficient than 17%EDTA in the removal of smear layer from the apical third of the root canal system, which is a crucial area for disinfection.     

Effectiveness of oxidative potential water as a root canal irrigant

AIM: The aim of this study was to evaluate the effectiveness of oxidative potential water (OPW) as an irrigant, based on its ability to remove the smear layer and/or debris from instrumented root canals. METHODOLOGY: One hundred and twenty root canals from extracted human maxillary incisors were instrumented using a conventional step-back technique with irrigation from sodium hypochlorite (NaOCl) or oxidative potential water (OPW). After instrumentation, the canals were irrigated by syringe or ultrasound using 15% EDTA or OPW as an irrigant. The volume of each irrigant used for syringe irrigation was 10, 20, and 30 mL, respectively, whilst the duration for ultrasonic irrigation was 1, 3, and 5 min, respectively. After irrigation, each root was split longitudinally in two with cutting pliers, and the specimens were prepared for SEM observation. The presence of debris and smear layer on each canal wall was assessed using a three-point scale for each parameter. RESULTS: Smear layer was effectively removed with EDTA both introduced via syringe and via ultrasonic irrigation. A similar effect was observed with OPW via syringe irrigation following instrumentation with 5% NaOCl. The canal walls in any of these cases showed open and patent dentinal tubules following smear layer removal. Some specimens irrigated with EDTA exhibited the effect of demineralization on the dentine resulting in funnelling of tubule orifices. Syringe irrigation was more effective in smear layer removal, except for ultrasonic irrigation with 15% EDTA, whilst ultrasonic irrigation was more effective in debris removal including the use of OPW as irrigant following instrumentation with 5% NaOCl. Neither syringe nor ultrasonic irrigation with OPW following instrumentation with OPW removed smear layer or debris effectively. CONCLUSIONS: The most effective irrigation technique for smear removal was 15% EDTA irrigation by means of syringe following instrumentation with 5% NaOCl solution. However, the most effective irrigation technique for debris removal was ultrasonic irrigation regardless of irrigant used. OPW irrigation by means of syringe following instrumentation with 5% NaOCl showed a similar effect to that of 15% EDTA irrigation for removal of smear layer and debris.     

Surface debris of canal walls after post space preparation in endodontically treated teeth: a scanning electron microscopic study

PURPOSE: To evaluate surface cleanliness of root canal walls along post space after endodontic treatment using 2 different irrigant regimens, obturation techniques, and post space preparation for adhesive bonding. STUDY DESIGN: Forty teeth, divided into 4 groups, were instrumented, using Ni-Ti rotary files, irrigated with NaOCl or NaOCl+EDTA and obturated with cold lateral condensation (CLC) or warm vertical condensation (WVC) of gutta-percha. After post space preparation, etching, and washing procedure, canal walls were observed using a scanning electron microscope (SEM). Amount of debris, smear layer, sealer/gutta-percha remnants, and visibility of open tubules were rated. RESULTS: Higher amounts of rough debris, large sealer/gutta-percha remnants, thick smear layer, and no visibility of tubule orifices were recorded in all the groups at apical level of post space. At middle and coronal levels areas of clean dentin, alternating with areas covered by thin smear layer, smaller debris, gutta-percha remnants, and orifices of tubules partially or totally occluded by plugs were frequently observed. CONCLUSIONS: After endodontic treatment, obturation, and post space preparation SEM analysis of canal walls along post space shows large areas (covered by smear layer, debris, and sealer/gutta-percha remnants) not available for adhesive bonding and resin cementation of fiber posts.     

Effect of final irrigation protocols on push‐out bond strength of an epoxy resin root canal sealer to dentin

The purpose of the present study was to evaluate the effect of different final irrigation protocols on push‐out bond strength of an epoxy resin root canal sealer to dentin. Eighty single‐rooted anterior teeth were used. The root canals were partially prepared using a rotary system and the final diameter was standardised using a #5 Gates‐Glidden drill prior to the push‐out bond test. During chemomechanical preparation, 5.25% NaOCl or 2% CHX gel was used. For smear layer removal, 17% ethylenediaminetetraacetic acid (EDTA) or QMix 2 in 1 was applied for 3 min. As final irrigant, 1 mL of NaOCl, CHX solution or distilled water was used. On conclusion of preparation, canals were filled with gutta‐percha/AH Plus sealer. Bond strength was measured by the push‐out test. Data were statistically analysed by Kruskal–Wallis and Mann–Whitney U‐tests. The group NaOCl/EDTA/NaOCl showed significantly higher bond strength values than other groups. In all groups, there were mainly mixed failure patterns. It can be concluded that 5.25% NaOCl proved to be the best solution for the final irrigation when combined with EDTA. The final irrigation protocols affect the push‐out bond strength of AH Plus to dentin.     

The effect of application time of EDTA and NaOCl on intracanal smear layer removal: an SEM analysis

AIM: To verify, under the scanning electron microscope (SEM), the influence of irrigation time with ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl) on intracanal smear layer removal. METHODOLOGY: Twenty-one extracted human permanent teeth with single straight root canals were included. The root canals of the teeth were instrumented and, at the end of preparation, were irrigated with 3 mL of 15% EDTA, followed by 3 mL of 1% NaOCl for 1 min (group 1), for 3 min (group 2), and for 5 min (group 3). The canals of teeth in group 4 (control) did not receive the final irrigation. The teeth were sectioned longitudinally and prepared for an SEM. The dentinal wall of cervical, middle and apical thirds was graded according to the amount of debris and smear layer remaining on the walls. The results were analysed using the Kruskal-Wallis and Conover-Inman tests. RESULTS: In all the canals of experimental groups irrigation with EDTA and NaOCl completely removed the smear layer from the cervical and middle thirds. In the apical third, the dentine surface were partially covered, particularly in the teeth of group 1, where there was significantly more smear layer when compared with the other thirds in the same group (P<0.007). However, the Kruskal-Wallis test showed overall that there were no significant differences between groups 1, 2 and 3 (P>0.05). CONCLUSION: In this limited laboratory study, canal irrigation with EDTA and NaOCl for 1, 3 and 5 min were equally effective in removing the smear layer from the canal walls of straight roots.     

An ex vivo evaluation of a new root canal irrigation technique with intracanal aspiration

AIM: To evaluate the effectiveness of a new root canal irrigation technique with intracanal aspiration in removing the smear layer and to assess irrigant extrusion ex vivo. METHODOLOGY: Thirty-five instrumented canals of extracted human canine teeth that had been resected apically by removing 3 mm of the root tip were divided into one control and four experimental groups of seven teeth each. The roots were fixed in a plastic case and surrounded with normal saline agar coloured with 1% acid red. No irrigation was performed in the control teeth. Each root canal in the experimental groups was irrigated with 9 mL of 14% ethylenediaminetetraacetic acid for 3 min, and then with 6 mL of 6% sodium hypochlorite (NaOCl) for 2 min. In the intracanal aspiration technique, the irrigant was delivered from the tip of an injection needle placed 12 mm from the apical root-end and an aspiration needle that was connected to a Root ZX apex locator placed 2 and 3 mm short of the apical root-end in groups 1 and 2, respectively. In the conventional method, the tip of an injection needle used for delivery of the irrigant and as an active electrode was placed 2 and 3 mm short of the apical root-end in groups 3 and 4, respectively, the tip of the aspiration needle was placed 12 mm from the apical root-end in these groups. The readings of the Root ZX during irrigation were recorded. The cleanliness of the canal was evaluated by scoring smear layer from scanning electron microscopy (SEM) images of the canal. Extrusion of NaOCl was detected by measuring the discoloured area of the agar around the apical root-end. The data obtained were statistically analysed by one-way anova, the Kruskal-Wallis test and Friedman's test. RESULTS: In the SEM study, the canals in groups 1-3 were significantly cleaner than those in the control and group 4 (P < 0.05). The mean Root ZX readings in groups 1-3 were approximately "0.5". The discoloured area in group 3 was significantly larger than the other groups (P < 0.05). CONCLUSIONS: Irrigation using the intracanal aspiration technique allowed more effective removal of the smear layer than that performed by the conventional method in an apically resected canine tooth. The intracanal aspiration technique produced limited extrusion of the irrigant beyond the apical foramen.     

Effect of Different Irrigation on Smear Layer Removal after Post Space Preparation

The purpose of this study was to evaluate the effect of different irrigating solutions on smear layer removal and dentinal tubule opening on root canal surfaces after post space preparation and to study whether additional ultrasonic irrigation has any effect on smear layer removal. Forty-eight anterior teeth were treated endodontically. After post space preparation, they were assigned to six groups: group 1, EDTA; group 2, EDTA with ultrasonic activation; group 3, sodium hypochlorite (NaOCl); group 4, NaOCl with ultrasonic activation; group 5, sodium chloride (NaCl); and group 6, NaCl with ultrasonic activation. Specimens were examined under a field-emission scanning electron microscope and scored for debris removal and dentinal tubule opening at the coronal, middle, and apical thirds of the root canal. The results showed that EDTA performed significantly better than NaCl and NaOCl in smear layer removal and dentinal tubule opening. Additional ultrasonic irrigation did not improve smear layer removal significantly.     

Effects of irrigation on debris and smear layer on canal walls prepared by two rotary techniques: a scanning electron microscopic study

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.     

Efficacy of different final irrigation activation techniques on smear layer removal

Introduction

Different techniques and irrigant delivery devices have been proposed to increase the flow and distribution of irrigating solutions within the root canal system. The aim of this study was to compare smear layer removal after final irrigant activation with apical negative pressure (ANP), manual dynamic agitation (MDA), and passive ultrasonic irrigation (PUI).

Methods

Forty single-rooted human mandibular premolars were decoronated to a standardized length of 16 mm. They were cleaned and shaped by using ProTaper system to size F4 and NaOCl 2.5%. The specimens were divided into 4 equal groups (n = 10) according to the final irrigation activation technique: group 1, passive irrigation (PI); group 2, apical negative pressure (ANP) (EndoVac); group 3, manual dynamic activation (MDA); and group 4, passive ultrasonic irrigation (PUI). Samples were split longitudinally and examined under scanning electron microscope for smear layer presence.

Results

PI and PUI had the highest smear scores, with no significant differences between them. This was followed by MDA and finally ANP, which showed the statistically significant lowest mean score at P ≤ .05.

Conclusions

Final irrigant activation with ANP and MDA resulted in better removal of the smear layer than with PUI or PI.     

A comparative scanning electron microscopy evaluation of smear layer removal with apple vinegar and sodium hypochlorite associated with EDTA

Objective

The purpose of this study was to evaluate by scanning electron microscopy (SEM) the removal of smear layer from the middle and apical root thirds after use of different irrigating solutions.

Material and Methods

Forty roots of permanent human teeth had their canals instrumented and were randomly assigned to 4 groups (n=10), according to the irrigating solution: apple vinegar (group A), apple vinegar finished with 17% ethylenediaminetetraacetic acid (EDTA) (group B), 1% sodium hypochlorite (NaOCl) finished with 17% EDTA (group C) and saline (group D - control). After chemomechanical preparation, the roots were cleaved longitudinally and their middle and apical thirds were examined by SEM at ×1,000 magnification. Two calibrated examiners (kappa=0.92) analyzed the SEM micrographs qualitatively attributing scores that indicated the efficacy of the solutions in removing the smear layer from the surface of the dentin tubules (1 - poor, 2 - good and 3 - excellent). Data from the control and experimental groups were analyzed by the Kruskal-Wallis and Dunn''s test, while the Wilcoxon test was used to compare the middle and apical thirds of the canals within the same group (α=0.05).

Results

The middle third presented less amount of smear layer than the apical third, regardless of the irrigant. There was statistically significant difference (p=0.0402) among the groups in the middle third. In the apical third, the apple vinegar/EDTA group showed the greatest removal of smear layer (p=0.0373).

Conclusion

Apple vinegar associated or not with EDTA was effective in removing smear layer when used as an endodontic irrigant.     

Effect of three radicular dentine treatments and two luting cements on the regional bond strength of quartz fibre posts

The purpose was to investigate by push-out tests and scanning electron microscopy (SEM)/energy-dispersive spectroscopy (EDS) the effect, after first acid etching the post space walls, of three radicular dentine treatments on the regional bond strength of quartz fibre posts placed using two heavily filled resin luting cements. The crowns of 39 extracted maxillary central incisors were sectioned transversely 2 mm coronal to the labial cement-enamel junction and the roots endodontically treated. After standardized post space preparations and etching 15 s with 32% phosphoric acid, 36 roots were randomly divided into six equal groups. Quartz fibre posts (D.T. LIGHT-POST) were placed using three radicular dentine treatments (0.9% sodium chloride (NaCl) for 60 s, 10% sodium hypochlorite (NaOCl) for 60 s, 17% ethylenediaminetetraacetic acid (EDTA) for 60 s followed by 5.25% NaOCl for 60 s) and two resin composite luting cements (ONE-STEP PLUS/DUO-LINK; ONE-STEP PLUS/LuxaCore Dual). Transverse segments (S1–S7), 1.00 mm (SD = 0.05 mm) thick, were sectioned from the coronal 8 mm of each root. Push-out bond strength tests were performed on coronal, middle and apical post space segments (S2, S4, S6) at a crosshead speed of 0.5 mm/min. Data were recorded and analyzed using a two-way mixed ANOVA design (a = 0.05). Three segments (S1, S5, S7) from roots in each group were examined using SEM/EDS. After post space preparation, acid etching and using each of the three radicular dentine treatments, the three remaining roots were sectioned longitudinally for SEM observation of the post space walls. At all root segment sites, the mean bond strengths from using 0.9% NaCl were significantly lower than for the other two radicular dentine treatments (P ≤ 0.02), and DUO-LINK cement had significantly higher mean bond strengths than LuxaCore Dual cement (P ≤ 0.01). There was a significant linear trend for reduced bond strengths from coronal to apical post space segments (P < 0.001), which was supported by the SEM/EDS observations of dentine tubule appearance and resin tag formation. Acid etching followed by either 10% NaOCl or 17% EDTA and 5.25% NaOCl dentine treatments of the post spaces provided good adhesion and resin luting cement tag infiltration of dentinal tubules in the coronal and middle segments in particular.     

Effect of smear layer deproteinizing on resin–dentine interface with self-etch adhesive

Objectives

This study aimed to investigate deproteinizing effect of sodium-hypochlorite (NaOCl) and mild acidic hypochlorous-acid (HOCl) pretreatment on smear layer-covered dentine and to evaluate their effects on morphological characteristics of resin–dentine interface with self-etch adhesive.

Methods

Human coronal-dentine discs with standardized smear layer were pretreated with 6% NaOCl or 50 ppm HOCl for 15 s or 30 s. Their deproteinizing effects at the treated smear layer-covered dentine surfaces were determined by the measurement of amide:phosphate ratio using ATR-FTIR analysis. In addition, using TEM, micromorphological alterations of hybridized complex and nanoleakage expression were evaluated at the interface of a self-etch adhesive (Clearfil SE Bond) to the pretreated dentine surface with or without subsequent application of a reducing agent (p-Toluenesulfinic acid salt; Accel^®).

Results

Both pretreatments of NaOCl and HOCl significantly reduced the amide:phosphate ratio as compared with the no-pretreated group (p < 0.05), coincident with the elimination of the hybridized smear layer on their bonded interfaces. Nanoleakage within the hybrid layer was found in the no-pretreated and NaOCl-pretreated groups, whereas the subsequent reducing agent application changed the reticular nanoleakage to spotted type. HOCl-pretreated groups showed less nanoleakage expression in a spotted pattern, regardless of reducing agent application.

Conclusions

NaOCl and HOCl solutions could remove the organic component on the smear layer-covered dentine, which could eliminate the hybridized smear layer created by self-etch adhesive, leading to the reduction of nanoleakage expression within hybrid layer.

Clinical significance

Smear layer deproteinizing could modify dentine surface, giving an appropriate substrate for bonding to self-etch adhesive system.     

5种冲洗剂组合对前牙直根管清洁效果的比较

目的：比较5种冲洗剂组合对前牙直根管的清洁效果。方法：25颗离体直根管前牙,随机分为5组,不锈钢K锉常规法预备根管．应用5种冲洗剂组合进行冲洗。第1组：根管器械预备期间和预备结束后依次用1％NaOCl和3％H2O2冲洗;第2组：根管器械预备期间用1％NaOCl冲洗,预备结束后用17％EDTA冲洗;第3组：根管器械预备期间和预备结束后依次用1％NaOCl和17％EDTA冲洗：第4组：根管器械预备期间依次用17％EDTA和1％NaOCl冲洗,器械预备结束后用17％EDTA冲洗;第5组：根管器械预备期间依次用17％EDTA、1％Triton X-100(表面活性剂)和1％NaOCl冲洗．器械预备结束后用17％EDTA冲洗。每组冲洗剂剂量和冲洗时间均为22ml和7min。将牙纵劈后进行扫描电镜观察。结果：第1组,根管壁上见典型玷污层结构和大量杂质和残屑。第2组在根管冠、中1／3能部分去除玷污层．根尖1／3残留大量玷污层。第3组虽然能有效去除玷污层．但会引起牙本质小管中度腐蚀。第5组在根管冠、中1／3能部分去除玷污层,但根管壁上黏着大量杂质和残屑．此外还存在重度腐蚀现象。第4组根管清洁效果最好,且对牙本质小管无腐蚀性。结论：在严格控制冲洗时间和顺序的情况下,联合应用17％EDTA和1％NaOCl能有效去除玷污层．且不会腐蚀牙本质小管。