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PubMed2001

Effects of rotary instrumentation and different etchants on removal of smear layer on human dentin.

STATEMENT OF PROBLEM: Various methods of rotary preparation and conditioning of teeth affect surface topography and may affect the retention of dental restorations. PURPOSE: This study microscopically evaluated dentin surfaces prepared by different rotary instruments and etched using several types of acid etchants that have been deemed suitable dentin conditioners. MATERIAL AND METHODS: Occlusal surfaces of 35 extracted human molars were ground wet with 320-grit silicon carbide paper to the depth of the central groove and then prepared with diamond (n = 5) and finishing burs (n = 30). Five specimens from each group were used for SEM evaluation of mechanical preparation effects. Dentin specimens (n = 5) prepared with finishing burs were then etched with 1 of 5 etchants (25% polyacrylic acid, 10% phosphoric acid, 10% citric acid, 20% lactic acid, or 32% phosphoric acid) for 10 seconds. Specimens were critical-point dried and freeze fractured for SEM analysis. RESULTS: Diamond rotary instruments created more undulating surfaces than finishing burs. Fine grooves were observed running perpendicular to undulations and parallel to the direction of instrument rotation. Specimens prepared with finishing burs exhibited a smooth surface interrupted by only a slight granularity. The amorphous smear layer was partially removed after the application of 25% polyacrylic acid (pH 1.53), but all dentinal tubules contained plugs. The number of dentin tubules containing plug material and the amount of material in the tubules decreased noticeably with 10% phosphoric acid (pH 0.86), and the dentin surface had an appearance similar to the specimen etched with 10% citric acid (pH 1.70). The surfaces treated with 20% lactic acid (pH 1.40) produced a clearly etched surface with minimal demineralization. Etching of dentin with 32% phosphoric acid (pH 0.16) revealed significant changes in dentin with the evidence of increased tubule diameter. CONCLUSION: Differences related to the method of instrumentation were found in the surface characteristics of dentin. The degree of smear layer removal was related to the pH of the acid etchant.

Acid Etching, Dental↗
PubMed2006

The role of Carisolv and different auxiliary chemical substances in the removal of bovine root canal smear layer.

UNLABELLED: To evaluate the effectiveness of Carisolv and different auxiliary chemical substances in root canal smear layer (SL) removal. SL was produced in the centre of 40 hemi-disks of bovine root dentine. The samples were divided into four irrigation groups (G): GI (control) - 0.9% NaCl; GII - 1% NaOCl + 0.9% NaCl; GIII - Carisolv + 0.9% NaCl; GIV - 1% NaOCl + 10% citric acid solution + 0.9% NaCl. The photomicrographs (SEM analysis) were coded (0 - absence of SL; 1 - moderate SL; 2 - dense SL with visible tubules; 3 - dense SL with no visible tubules). GIV was more effective in SL removal (P < 0.01). It should be noted that GI and GIII obtained score 3 in 100% of the samples (P > 0.01). CONCLUSION: NaOHCl, citric acid and NaCl solutions, when used together, presented a better performance in the removal of SL when compared to the other solutions.

Animals↗
PubMed1978

Adhesive bonding of various materials to hard tooth tissues--solubility of dentinal smear layer in dilute acid buffers.

While the acid etch technique has largely solved the problem of bonding restorative materials to enamel, attempts to improve adhesive bonding to dentin have so far had only limited success. One aspect to which insufficient attention has been paid is the presence of a smear layer on cut surfaces and of pellicle on surfaces exposed to saliva, both of which would reduce or prevent durable adhesive bonds. The present study attempts to evaluate the usefulness of various acidic solutions in removing these surface layers while causing minimal damage to the vital contents of the dentinal tubules. A series of twelve 0.16 M buffer solutions were applied to cut dentin surfaces which were then washed, dried and sputter-coated with gold/palladium in preparation for examination by scanning electron microscopy. It is concluded that the smear layer on cut dentin surfaces can be substantially removed in vitro by a 30 second exposure to an isotonic solution of buffered monobasic acids having pKa values between 3.8 and 2.5. Since these solutions did not always remove material from grooves in the prepared surface clinical techniques should aim at producing a smooth cut surface. The response of the vital pulp to this treatment still awaits investigation.

Acid Etching, Dental↗
PubMed2000

Morphological interface between hybrid ionomers and dentin with and without smear-layer removal.

To evaluate the micromorphological interface between dentin and several hybrid ionomer restoratives, a flat dentin surface was obtained on the occlusal surfaces of extracted human molar teeth after sectioning the enamel with an Isomet saw. Three poly-acid-modified composite resins, Compoglass, Dyract and F2000, and two resin-modified glass-ionomer cements, Fuji II LC and Photac-Fil were applied to the dentin surface. A second section, 2 mm apical from the first one, was made to produce a dentin segment containing the tested materials. Each disc was then split fractured along the dentin/material interface. For the poly-acid-modified composites, one half of the disc was stored in 6 mol/L HCl for 48 h to remove the dentin. The other was gently decalcified and deprotenized at the interface between the hybrid ionomer and the dentin. Both halves were then sputtered with gold and examined using SEM. For resin-modified glass-ionomer, samples were only evaluated at the interface. The three poly-acid-modified composite resins showed the formation of hybrid layers and resin tags at the interface to the dentin. Removal of the smear layer significantly improves hybridization of these materials. Also, Fuji II LC produced a hybrid layer while the Photac-Fil showed no evidence of hybridization.

Compomers↗
PubMed1996

Removal of smear layer in the root canal using oxidative potential water.

We investigated oxidative potential water (OPW) for its ability to remove the smear layer using a scanning electron microscope. OPW has been studied mainly in Japan and is known to suppress bacteria and viruses without harming living systems. We found that OPW used as in irrigant during and after root canal instrumentation is as effective as 5% NaOCl or 17% EDTA for opening and keeping patent the dentinal tubules.

Acid Etching, Dental↗
PubMed2005

Effect of smear layer thickness and acidity of self-etching solutions on early and long-term bond strength to dentin.

OBJECTIVES: To evaluate the effect of smear layer thickness (SL) on early and 6-month bond strength (BS) of self-etching adhesives to dentin and to measure the ultimate microtensile strength (UTS) of the adhesives. METHODS: Clearfil SE Bond; Optibond Solo Plus Self-Etch Primer; Tyrian Self Priming Etchant (TY) and as controls, Single Bond (SB) and Scotchbond Multi-Purpose Plus (SBMP) were applied on flat superficial dentin surface with thick and thin SL thicknesses. After adhesive's application (n=6) a resin build-up was made. After 24h, resin-dentin beams (0.8mm(2)) were prepared to be tested immediately and after 6-month (6M) at 0.5mm/min. For the UTS measurement, hour-glass specimens were prepared with the bonding resin alone or after mixing (1:1). BS values were analyzed by three-way repeated measures ANOVA and Tukey's multiple comparison tests. Two-way ANOVA (bonding resin and bonding resin+self-etching primer) and Tukey's test were used for the UTS values. The bonding resins were re-evaluated separately by a one-way ANOVA and Tukey's test, since Single Bond is a one-bottle adhesive (alpha=0.05). RESULTS: The SL thickness was not significant (p=0.64). BS values were reduced after 6M, except for the SBMP. TY provided the lowest BS mean while SB and SBMP the highest BS. The UTS of the SBMP was the highest. TY yielded the lowest UTS. Regression analysis revealed a linear and significant relationship between the UTS of self-etch systems and the mean BS (R=0.95, p=0.02). CONCLUSIONS: The performance of a self-etching system does not seem to be dependent on the SL thickness. The total-etch, three-step system provided the highest BS to dentin and maintained the BS stable over 6 months. The performance of the self-etching systems can be envisaged by their UTS.

Acid Etching, Dental↗
PubMed2004

Effect of three different time periods of irrigation with EDTA-T, EDTA, and citric acid on smear layer removal.

OBJECTIVE: An in vitro study was conducted to evaluate the effect of EDTA-T, 17% EDTA, and 10% citric acid on the removal of smear layer from root canal dentin after final irrigation for 3, 10, and 15 min. STUDY DESIGN: Root canals of 90 extracted human canines were divided into 9 groups of 10 teeth; each group received a final irrigation with one of the irrigants for the established time intervals. After irrigation, the teeth were split and prepared for SEM analysis to determine the number of open dentinal tubules. RESULTS: There were statistically significant better results (P <.05) when irrigation with 10% citric acid for 3 min was compared to 10 and 15 min, and when irrigation with EDTA for 3 min was compared to 15 min. In all cases, irrigation for 3 min presented the greatest number of open dentinal tubules. There were no significant differences (P>.05) for the 3 time intervals of irrigation for EDTA-T, although there were a greater number of open tubules at 3 min. CONCLUSION: These 3 irrigants were effective at the shortest time tested and did not demonstrate an improved effect with an increase in time.

Citric Acid↗
PubMed2006

Effect of the sodium hypochlorite and citric acid association on smear layer removal of primary molars.

This study aimed to assess the capacity of a sodium hypochlorite and citric acid (CA) association (the latter at different concentrations) in removing coronal smear layer (SL) of primary teeth. For this purpose, the pulp chamber roof and floor of 28 primary molars were removed to obtain enamel and dentine disks. SL was produced on the internal walls of the disks using high-speed drills. The disks were irrigated with 1% sodium hypochlorite and citric acid at different concentrations (CA-4%, CA-6%, CA-8% and CA-10%), and with 0.9% sodium chloride. The samples were split and observed under SEM. Scores were attributed to the obtained photomicrographs, according to the amount of SL present. It was noted that all the tested concentrations of citric acid used after the sodium hypochlorite were capable of removing SL. The results were analyzed by the Kruskal-Wallis test, and there was no significant statistical difference among the scores of the groups tested. However, it was observed that CA-8% and CA-10% caused peritubular dentine destruction, and that CA-4% presented a larger number of samples with dense SL. Based on these results, 6.0% citric acid in association with 1% sodium hypochlorite is suggested as auxiliary chemical substances for primary teeth irrigation.

Chelating Agents↗
PubMed1991

Scanning electron microscopy and dentinal permeability analysis of smear layer.

The aim of the present study was to evaluate the surface morphology and the permeability of dentine after different acid treatments: polyacrylic acid, maleic acid, phosphoric acid and saline solution as control. Dentine permeability was expressed as hydraulic conductance. All the acid treatments removed the smear layer and increased the dentine permeability.

Acid Etching, Dental↗
PubMed1995

The effects of intracanal medicaments, fillers, and sealers on the attachment of human gingival fibroblasts to an exposed dentin surface free of a smear layer.

To date there has been very little research into the possible effects of endodontic therapy on regeneration of the lost periodontal attachment. The objective of this study was to examine the effects of endodontic medicaments on fibroblast attachment to dentin surfaces free of a smear layer. Pulp chambers of extracted third molars were filled with one of the following medicaments: gutta-percha with Roth's zinc oxide and eugenol-based sealer, warm gutta-percha with sealer, warm gutta-percha without sealer, calcium hydroxide, formocresol, cotton pellet, or left empty. A predetermined dentin surface area was then inoculated with human gingival fibroblasts at a concentration of 2 x 10(4) cells per ml. The cells were allowed to adhere to the dentin surface for either 4 or 24 hours, then cell attachment was quantified using a methyl-tetrazolium assay. The data were analyzed using a Kruskal-Wallis one-way analysis of variance and Dunn's multiple comparison test. It was determined that fibroblast attachment was significantly reduced when exposed to formocresol or warm gutta-percha without sealer at both the 4 and 24 hour interval (P < or = 0.05). This suggests that the use of formocresol or warm gutta-percha without sealer in a root canal may impede periodontal wound healing and regeneration.

Analysis of Variance↗
PubMed1991

Adhesion to dentin with and without smear layer under varying degrees of wetness.

The bond strengths of glass ionomer cements to prepared dentin ranged between 2.1 and 4.7 MPa for all test conditions and did not appear to be adversely affected by the presence of fluid under physiologic pressure or by the presence or absence of a smear layer. On the other hand, the resin dentin adhesive was adversely affected by the presence of moisture (1 +/- 1.3 MPa when the tubules were full of fluid and under pressure; 9.4 +/- 10.6 MPa when the tubules were full of fluid but not under pressure; and 18.3 +/- 7.6 MPa when the tubules were empty.

Acid Etching, Dental↗
PubMed1992

Calcium oxalate smear layer: mineralogical and crystallographic study.

Different methods to reduce dentine hypersensitivity have been tested by means of oxalate treatments. Natural material (20 teeth) and commercial oxalates have been employed. As a result the dentinal tubules are filled by small crystals preventing dental disease. Permeability measurements have been performed in order to quantify results. The composition of the synthetic smear layer produced after oxalate treatment have been investigated by powder diffraction method suggesting calcium oxalate formation.

Calcium Oxalate↗
PubMed2005

The effect on coronal leakage of liquid adhesive application over root fillings after smear layer removal with EDTA or Er:YAG laser.

OBJECTIVE: To evaluate coronal microleakage in filled root canals that received different biomechanical preparations and application of liquid adhesives over the root filling and the pulp chamber walls. STUDY DESIGN: Root canals of 94 extracted canine teeth were filled after being biomechanically prepared with 1% sodium hypochlorite and divided into 3 groups. In 2 groups attempts were made to remove the smear layer with either 17% EDTA or Er:YAG laser irradiation (10 Hz, 250 mJ input, 112 mJ output). Liquid adhesive (Super Bonder and Single Bond adhesive) was applied and the teeth were immersed for 90 days in India ink. RESULTS: Statistically significant differences were found for the different preparations, the use of liquid adhesives, and the different liquid adhesives. The use of Er:YAG laser, EDTA, and the liquid adhesive reduced coronal microleakage (P < .01). CONCLUSIONS: Because of the risk of coronal microleakage, endodontically treated teeth should be restored as quickly as possible.

Aluminum Silicates↗
PubMed1995

Effects of toothbrushing prior and/or subsequent to dietary acid application on smear layer formation and the patency of dentinal tubules: an SEM study.

Dentine sensitivity is a quite common condition, associated with open dentinal tubules patent all the way to the pulp. The purpose of this in vitro study was to assess the effects of toothbrushing preceded and/or followed by dietary acid application on the patency of dentinal tubules. Dentine sections were prepared from recently extracted human molars and, after removal of the smear layer, were treated as follows: 1) toothbrushing alone; 2) toothbrushing followed by exposure to orange juice; and 3) toothbrushing subsequent to orange juice exposure. All specimens were observed in the scanning electron microscope (SEM) at a standard magnification and the patency of the dentinal tubules estimated. Results showed that toothbrushing alone was the most effective in occluding the tubules, followed by toothbrushing subsequent to dietary acid application, and then by toothbrushing prior to dietary acid application. From the results of this study it may be that in cases of dentine sensitivity toothbrushing should not precede or follow dietary acid application but be separate from mealtimes. Clinical research is required to confirm the findings of this in vitro study.

Analysis of Variance↗
PubMed1999

Effect of endodontic smear layer and various solvents on the calcium ion diffusion through radicular dentin--an in vitro study.

External root resorption and ankylosis remains the major cause of failure of replanted teeth. This study was conducted to explore the different ways to increase the pH of periradicular area in order to overcome the problem of root resorption and ankylosis. 60 freshly extracted permanent anteriors were used after removing the crown at CEJ. After biomechanical preparation Ca (OH)2 was injected and assays were done using EDTA, Citric and tannic acid Assays were repeated. Calcium diffusion and pH in the root exterior was measured using spectrophotometer. Results showed that dentin is permeable to calcium & hydroxyl ions and placement of Ca (OH)2 in the canal resulted in its increased recovery and alkaline pH periradicularly. Smear layer removal did not result in significant increase in Ca++ recovery or alkaline pH however combination of EDTA & NaOCl was found best than the other two.

Calcium↗
PubMed1999

Scanning electron microscopy study of the effect of tetracycline HCl on smear layer removal and fibrin network formation.

Scanning electron microscopy (SEM) was used to evaluate root surface characteristics of human teeth affected with periodontitis following periodontal instrumentation and topical application of tetracycline HCl (TTC-HCl; pH 1.6; 4 min). Specimens were randomly assigned to periodontal instrumentation alone (control 1); periodontal instrumentation plus TTC-HCl (test 1); periodontal instrumentation plus trypsin solution after extraction (control 2); and periodontal instrumentation plus TTC-HCl plus trypsin solution after extraction (test 2). Tetracycline solution was applied with a cotton pellet. Twenty-two single root periodontitis affected human teeth scheduled for extraction were selected. Mucoperiosteal flaps were raised, root surfaces were mechanically and chemically treated, flaps were repositioned and maintained in place for 20 min. Teeth were extracted, rinsed and placed in cold phosphate buffer solution (PBS) and control 2 and test 2 groups were treated with trypsin solution. Specimens were examined using SEM. Smear layer was successfully removed, exposing dentinal tubules; however, fibrin network formation in situ was not improved by application of TTC-HCl.

Anti-Bacterial Agents↗
PubMed2003

Effect of smear layer on root demineralization adjacent to resin-modified glass ionomer.

The cariostatic effect of resin-modified glass ionomer (RMGI) on secondary root caries is well-documented. However, this beneficial effect may be dependent upon the mode of cavity surface treatment. To investigate this relationship, we studied 4 cavity surface treatments prior to the placement of RMGI: no treatment (None), polyacrylic acid (PAA), phosphoric acid (H(3)PO(4)), and Scotchbond Multi-Purpose adhesive (SMP) as a control. Specimens were aged for two weeks in synthetic saliva, thermocycled, and subjected to an artificial caries challenge (pH 4.4). Polarized light microscopy (PLM) and microradiography (MRG) showed significantly less demineralization with the H(3)PO(4) cavity surface treatment as revealed by ANOVA and Tukey's multiple comparisons (p < or = 0.05). Dentin fluoride profiles determined by electron probe microanalysis (EPMA) supported PLM and MRG findings. It may be concluded that removal of the smear layer with phosphoric acid provides significantly enhanced resistance to secondary root caries formation adjacent to RMGI restorations.

Acid Etching, Dental↗
PubMed1999

A three-year evaluation of restorations placed with a smear-layer-mediated dentin bonding agent in non-carious cervical lesions.

PURPOSE: To evaluate the handling characteristics, clinical behavior, and effectiveness of Coltene ART Bond/Brilliant restorations in mixed Class V preparations in maxillary premolar and canine teeth of adult patients over a three-year period. MATERIALS AND METHODS: Single-center, uncontrolled, clinical evaluation of 50 restorations in 26 patients extending over 36 months. RESULTS: At three years, 34 restorations, or 68% of those originally placed, in 20 patients were available for review. One of the 34 restorations had been lost 15 months after placement. In terms of marginal integrity and staining, anatomic form, surface texture and staining, and postoperative sensitivity, over 90% of the restorations reviewed at three years were rated alpha. Following difficulties in obtaining excellent color match in relation to 14 (28%) of the restorations at the time of placement, only 44% of the restorations were rated alpha at three years. CONCLUSION: It was concluded that with the possible exception of excellent color match, ART Bond/Brilliant restorations may be found to perform favorably in mixed Class V lesions in selected adult patients over a period of at least three years. The findings indicate that resin composite restorations placed with a smear-layer mediated dentin bonding agent may be found to have a favorable clinical outcome in non-carious cervical lesions.

Adult↗