Comparative analysis of root surface smear layer removal by different etching modalities or erbium:yttrium-aluminum-garnet laser irradiation. A scanning electron microscopy study

The purpose of this study was to evaluate the effect of erbium:yttrium-aluminum-garnet (Er:YAG) laser (2.94 mu m) irradiation on the removal of root surface smear layer of extracted human teeth and to compare its efficacy with that of citric acid, ethylenediamine tetra-acetic acid (EDTA), or a gel containing a mixture of tetracycline hydrochloride (HCl) and citric acid, using scanning electron microscopy (SEM). Thirty human dentin specimens were randomly divided into six groups: G1 (control group), irrigated with 10 ml of physiologic saline solution; G2, conditioned with 24% citric acid gel; G3, conditioned with 24% EDTA gel; G4, conditioned with a 50% citric acid and tetracycline gel; G5, irradiated with Er:YAG laser (47 mJ/10 Hz/5.8 J/cm(2)/pulse); G6, irradiated with Er:YAG laser (83 mJ/10 Hz/10.3 J/cm(2)/pulse). Electron micrographs were obtained and analyzed according to a rating system. Statistical analysis was conducted with Kruskal-Wallis and Mann-Whitney tests (P < 0.05). G1 was statistically different from all the other groups; no statistically significant differences were observed between the Er:YAG laser groups and those undergoing the other treatment modalities. When the two Er:YAG laser groups were compared, the fluency of G6 was statistically more effective in smear layer removal than the one used in G5 (Mann-Whitney test, P < 0.01). Root surfaces irradiated by Er:YAG laser had more irregular contours than those treated by chemical agents. It can be concluded that all treatment modalities were effective in smear layer removal. The results of our study suggest that the Er:YAG laser can be safely used to condition diseased root surfaces effectively. Furthermore, the effect of Er:YAG laser irradiation on root surfaces should be evaluated in vivo so that its potential to enhance the healing of periodontal tissues can be assessed.

Morphological analysis of human and bovine dentine by scanning electron microscope investigation

Objective: The objective of this study was to compare the superficial morphology of bovine and human sclerotic dentine. Design: For the morphological analysis, bovine (n = 3) and human (n = 3) incisors exhibiting exposed dentine were used. Dentine presented characteristics of sclerosis: brownish, smooth and shiny-the vitreous appearance. The teeth were prepared for assessment on a scanning electron microscope (SEM). Three pre-determined areas of each sample were submitted to SEM. The number of open tubules per area was obtained from the electron micrographs (n = 9 per group) for comparison purposes. Results: The number of open tubules in both species compared were similar (p > 0.05). Human dentine presented 31.89 +/- 23.94 open tubules per area, whereas bovine dentine showed 30.33 +/- 18.14 open tubules per area. Conclusion: Based on the results, we concluded that dentine exposed at the incisal surface of human and bovine teeth presented similar clinical and micro-morphological aspects, represented by surfaces with equivalent numbers of open dentinal tubules. (C) 2007 Elsevier Ltd. All rights reserved.

Scanning Electron Microscopy In Vitro Study on the Effect of Carisolv Application on Periodontally Diseased Root Surfaces

The purpose of this study was to evaluate the characteristics of diseased root surfaces treated by the association of scaling and the application of Carisolv. Twenty-four uniradicular periodontally involved teeth were used in this study The teeth were divided randomly into three groups: eight teeth were scaled and root planed until there was a complete visible removal of calculus (group 1), Carisolv was applied on the root surfaces of eight teeth twice for 30 seconds before scaling with a sharp curette (group 2), and eight teeth received the same treatment as in group 2 but with a blunt curette (group 3). Specimens were examined using scanning electron microscopy The superficial aspect of the roots from group 1 presented scratches that mirrored the curette cutting edge, and the smear layer completely covered the surface. Root surfaces from groups 2 and 3 also presented a smear layer that covered the surface completely but it was somewhat smoother than group 1. The use of Carisolv as an adjunct to scaling and root planing presented no advantage for smear layer removal over scaling alone, suggesting that no benefit is obtained by the use of Carisolv during periodontal mechanical treatment. (Int J Periodontics Restorative Dent 2011;31:91-95.)

Effects of Ultramorphological Changes on Adhesion to Lased Dentin-Scanning Electron Microscopy and Transmission Electron Microscopy Analysis

Dentin irradiation with erbium lasers has been reported to alter the composite resin bond to this treated surface. There is still a lack of studies reporting the effect of erbium lasers on dentin organic content and elucidating how laser treatment could interfere in the quality of the resin-dentin interface. This study aimed to evaluate the effect of erbium laser irradiation on dentin morphology and microtensile bond strength (lTBS) of an adhesive to dentin. Seventy-two dentin disks were divided into nine groups (n = 8): G1-Control (600-grit SiC paper); Er:YAG groups: G2-250 mJ/4 Hz; G3-200 mJ/4 Hz; G4-180 mJ/10 Hz; G5-160 mJ/10 Hz; Er, Cr:YSGG groups: G6-2 W/20 Hz; G7-2.5 W/20 Hz; G8-3 W/20 Hz; G9-4 W/20 Hz. Specimens were processed for cross-sectional analysis by scanning electron microscopy (SEM) (n = 3), transmission electron microscopy (TEM) (n = 2), and adhesive interface (n = 3). Forty-five dentin samples (n = 5) were restored and submitted to lTBS testing. ANOVA (alpha = 5%) revealed that G1 presented the highest lTBS values and irradiated groups did not differ from each other. TEM micrographs showed a superficial layer of denatured collagen fibrils. For SEM micrographs, it was possible to verify the laser effects extending to dentin subsurface presenting a rough aspect. Cross-sectional dentin micrographs of this hybridized surface revealed a pattern of modified tags with ringlike structures around it. This in vitro study showed that erbium laser irradiation interacts with the dental hard tissue resulting in a specific morphological pattern of dentin and collagen fibrils that negatively affected the bond strength to composite resin. Microsc. Res. Tech. 74:720-726, 2011. (C) 2010 Wiley-Liss, Inc.

Adhesives bonded to erbium:yttrium-aluminum-garnet laser-irradiated dentin: transmission electron microscopy, scanning electron microscopy and tensile bond strength analyses

The aim of this in vitro study was to investigate the effect of erbium:yttrium-aluminum-garnet (Er:YAG) laser irradiation on dentinal collagen by transmission electron microscopy and to analyze the resin-dentin interface by scanning electron microscopy. A tensile bond strength test was also applied. Specimens from 69 sound human third molars were randomly divided into three groups: control (no laser), and two irradiated groups, laser 250 (250 mJ/2 Hz) and laser 400 (400 mJ/4 Hz). Then, specimens were restored with two adhesive systems, an etch-and-rinse or a self-etch system. Although ultrastructural examination showed a modified surface in the irradiated dentin, there was no statistical difference in bond strength values between the laser groups and controls (P < 0.05). In conclusion, the use of Er:YAG laser for ablating human dentin did not alter the main adhesion parameters when compared with those obtained by conventional methods, thus reinforcing its use in restorative dentistry.

Effect of the Combination of Sodium Hypochlorite and Chlorhexidine on Dentinal Permeability and Scanning Electron Microscopy Precipitate Observation

Introduction: This study compared the combined use of sodium hypochlorite (NaOCl) and chlorhexidine (CXH) with citric acid and CXH on dentinal permeability and precipitate formation. Methods: Thirty-four upper anterior teeth were prepared by rotary instrumentation and NaOCl. The root canal surfaces were conditioned for smear layer removal using 15% citric acid solution under ultrasonic activation and a final wash with distilled water. All teeth were dried, and 30 specimens were randomly divided into three equal groups as follows: positive control group (PC), no irrigation; 15% citric acid + 2% CHX group (CA + CHX); and 1% NaOCl + 2% CHX group (NaOCl + CHX). All roots were immersed in a 0.2% Rhodamine B solution for 24 hours. One-millimeter-thick slices from the cementum-enamel junction were scanned at 400 dpi and analyzed using the software ImageLab (LIDO-USP, Sao Paulo, Brazil) for the assessment of leakage in percentage. For scanning electron microscopy analysis, four teeth, irrigated for NaOCl + CHX samples, were split in half, and each third was evaluated at 1,000x and 5,000x (at the precipitate). Results: Using the analysis of variance test followed by the Bonferroni comparison method, no statistical differences between groups were found when analyzed at the cervical and medium thirds. At the apical third, differences between the PC and NaOCl + CHX (p<0.05) and CA + CHX and NaOCl + CHX could be seen (p < 0.05). Conclusion: The combination of 1% NaOCl and 2% CHX solutions results in the formation of a flocculate precipitate that acts as a chemical smear layer reducing the dentinal permeability in the apical third. (J Endod 2010;36:847-850)

Environmental and Individual Factors Associated with Nail Fluoride Concentration

Nails have been suggested as suitable biomarkers of exposure to F, with the advantage of being easily obtained. The effect of water F concentration, age, gender, nail growth rate and geographical area on the F concentration in the fingernail and toenail clippings were evaluated. Volunteers (n = 300) aged 3-7, 14-20, 30-40 and 50-60 years from five Brazilian communities (A-E) participated. Drinking water and nail samples were collected and F concentration was analyzed with the electrode. A reference mark was made on each nail and growth rates were calculated. Data were analyzed by ANOVA and linear regression (alpha = 0.05). Mean water F concentrations (8 SE, mg/l) were 0.09 +/- 0.01, 0.15 +/- 0.01, 0.66 +/- 0.01, 0.72 +/- 0.02, and 1.68 +/- 0.08 for A-E, respectively. Mean F concentrations (+/- SE, mg/kg) ranged between 1.38 +/- 0.14 (A, 50-60 years) and 10.20 +/- 2.35 (D, 50-60 years) for fingernails, and between 0.92 +/- 0.08 (A, 14-20 years) and 7.35 +/- 0.80 (E, 50-60 years) for toenails. Among the tested factors, geographical area and water F concentration exerted the most influence on finger- and toenail F concentrations. Subjects of older age groups (30-40 and 50-60 years) from D and E showed higher nail F concentrations than the others. Females presented higher nail F concentration than males. Water F concentration, age, gender and geographical area influenced the F concentration of finger- and toenails, and hence should be taken into account when using this biomarker of exposure to predict risk for dental fluorosis. Copyright (C) 2009 S. Karger AG, Basel

Depth and percentage of penetration of endodontic sealers into dentinal tubules after root canal obturation using a lateral compaction technique: A confocal laser scanning microscopy study

Objective. The aim was to compare the percentage and depth of sealer penetration into dentinal tubules during obturation using Sealer 26, GuttaFlow, or Sealapex in root canals filled with the lateral compaction technique. Study design. Thirty root canals filled with the lateral compaction technique using GuttaFlow (n = 10), Sealapex (n = 10), or Sealer 26 (n = 10) were analyzed using confocal microscopy. The teeth were sectioned at 3 and 5 mm from the apex, and statistical analyses was performed using analysis of variance-Tukey test (P < .05). Results. Sealapex showed the deepest sealer penetration at both levels evaluated (P < .05). No statistically significance was found between Sealer 26 and GuttaFlow at the 3 mm and 5 mm levels. No statistical significance was found in the percentage of penetration around the root canal wall among the 3 sealers evaluated at both levels. Conclusions. Although Sealapex displayed deeper penetration into the dentinal tubules there was no difference in the percentage of adaptation to the root canal walls among the 3 sealers evaluated. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 108: 450-457)

Ultrasonic Chemical Vapor Deposition-coated Tip versus High- and Low-speed Carbide Burs for Apicoectomy: Time Required for Resection and Scanning Electron Microscopy Analysis of the Root-end Surfaces

This study compared ultrasonic chemical vapor deposition (CVD)-coated tip (CVDentus #8.1117-1; Clorovale Diamantes Ind. e Com. Ltda Epp, Sao Jose dos Campos, SP, Brazil) versus high-speed (#FG700L) and low-speed (#699) carbide burs for apicoectomy, evaluating the time required for resection and analyzing the root-end surfaces by scanning electron microscopy. Thirty extracted human premolars had the canals instrumented and obturated and were randomly assigned to 3 groups (n = 10), according to the instrument used for root-end resection. The time required for resection of the apical 2 mm of each root was recorded. The resected apical segments were dried, sputter coated with gold, and examined with a scanning electron microscope at X 350 magnification. A four-point (0-3) scoring system was used to evaluate the apical surface smoothness. The results were analyzed statistically by the Kruskal-Wallis test and two-by-two comparisons analyses were performed using the Miller test. The significance level was set at 5%. Root-end resection with the high-speed bur was significantly faster (p < 0.05) compared with the low-speed bur and CVD tip. The carbide burs produced significantly smoother root-end surfaces than the CVD tip (p < 0.05). The low-speed bur produced the smoothest root-end surfaces, whereas the roughest and most irregular root ends (p < 0.05) were obtained with the CVD tip. However, no statistically significant difference (p > 0.05) was found between the high- and low-speed burs regarding the surface roughness of the resected root ends (p > 0.05). In conclusion, under the tested conditions, ultrasonic root-end resection took a longer time and resulted in rougher surfaces compared with the use of carbide burs at both high and low speed. (J Endod 2009;35:265-268)

Confocal laser scanning microscopy is appropriate to detect viability of Enterococcus faecalis in infected dentin

The purpose of this study was to explore the potential of confocal laser scanning microscopy (CLSM) for in situ identification of live and dead Enterococcus faecalis in infected dentin. Eight cylindrical dentin specimens were infected with Enterococcus faecalis in BHI for 21 days. After the experimental period, the specimens were stained with fluorescein diacetate (FDA) and propidium iodide (PI) or acridine orange (0.01 %) and analyzed by CLSM. Two noninfected dentin specimens were used as negative controls. CLSM analysis shows that the discrimination between viable (green) and dead (red) bacteria in infected dentinal tubules could be observed after staining with FDA/PI. Acridine orange was able to show metabolic activity of the E. faecalis cells inside the dentinal tubules showed by its red fluorescence. The viability of bacteria in infected dentin can be determined in situ by CLSM. FDA/PI and acricline orange are useful for this technique.

Evaluation of sutures after immersion in nonalcoholic benzydamine hydrochloride mouthrinse by scanning electron microscopy

This study evaluated the surface integrity of sutures after immersion in mouthrinse or water, by scanning electron microscopy (SEM) analysis. Pieces of resorbable suture remaining after oral surgery were immediately collected. Twelve pieces each of catgut, chromed catgut, and polyglactin 910 were divided into four groups and immersed in pure mouthrinse, mouthrinse diluted in water at 1:1 and 1:2, or water (positive control), for 24 h. Three pieces each of new sutures were used as negative control. Specimens were placed on stubs and sputter coated with gold for SEM analysis. Observation of experimental groups and comparison with controls revealed that immersion in the mouthrinse at different dilutions did not alter their surface; slight, nonsignificant changes were found in some experimental specimens yet also in the positive control group. It was concluded that immersion of resorbable sutures in water or non-alcoholic benzydamine hydrochloride mouthrinse did not produce any significant change; therefore, this mouthrinse may be safely employed after oral surgery.

Atomic Absorption Spectrometry and Scanning Electron Microscopy Evaluation of Concentration of Calcium Ions and Smear Layer Removal With Root Canal Chelators

Aim. The aim of this study was to evaluate the concentration of calcium ions and smear layer removal by using root canal chelators according to flame atomic absorption spectrophotometry and scanning electron microscopy. Forty-two human maxillary central incisors were irrigated with 15% ethylenediaminetetraacetic acid (EDTA), 10% citric acid, 10% sodium citrate, apple vinegar, 5% acetic acid, 5% malic acid, and sodium hypochlorite. The concentration of calcium ions was measured by using flame atomic absorption spectrometry, and smear layer removal was determined by scanning electron microscopy. Mean +/- standard deviation, one-way analysis of variance, Tukey-Kramer, Kruskal-Wallis, Dunn, and kappa tests were used for statistical analysis. The use of 15% EDTA resulted in the greatest concentration of calcium ions followed by 10% citric acid; 15% EDTA and 10% citric acid were the most efficient solutions for removal of smear layer. (J Endod 2009;35:727-730)