Effects of Er,Cr:YSGG laser parameters on dentin bond strength and interface morphology

Previous studies have shown the effects of Er,Cr:YSGG laser irradiation on the dentin bond strength; but there are few reports that show the significance of the irradiation with different laser parameters on dentin bond strength and interface morphology. This in‐vitro study attempted to evaluate the microtensile bond strength (μTBS) and interface morphology of resin‐dentin interfaces, either followed by treatment with Er,Cr:YSGG laser irradiation with different parameters or not. The flattened dentin samples of 35 bovine teeth were embedded into acrylic blocks and randomly divided into seven groups according to surface treatments using Er,Cr:YSGG lasers with different parameters: 3 W/20 Hz, 3 W/35 Hz, 3 W/50 Hz, 1.5 W/20 Hz, 1.5 W/35 Hz, 1.5 W/50 Hz, or no laser treatment (n = 5). Composite buildups were done over bonded surfaces and stored in water (24 hours at 37°C). Specimens were sectioned into sticks that were subjected to μTBS testing and observed under FE‐SEM. Control groups (27.70 ± 7.0) showed statistically higher values than laser‐irradiated groups. There were no significant differences among laser groups. Despite that, increasing the pulse frequency yielded slightly higher bond strength. Depending on laser settings, Er,Cr:YSGG laser irradiation caused interfacial gaps and resin tags with wings morphology. With the parameters used in this study, Er,Cr:YSGG laser irradiation promoted morphological changes within resin‐dentin interfaces and negatively influenced the bond strength of adhesive systems. Microsc. Res. Tech. 78:1104–1111, 2015. © 2015 Wiley Periodicals, Inc.     

A microscopic analysis of the effects of root surface scaling with different power parameters of er,cr:YSGG laser

The aim of this study was to evaluate the effects of different power parameters of an Erbium, Cromium: Yttrium, Scandium, Gallium, Garnet laser (Er,Cr:YSGG laser) on the morphology, attachment of blood components (ABC), roughness, and wear on irradiated root surfaces. Sixty‐five incisive bovine teeth were used in this study, 35 of which were used for the analysis of root surface morphology and ABC. The remaining 30 teeth were used for roughness and root wear analysis. The samples were randomly allocated into seven groups: G1: Er,Cr:YSGG laser, 0.5 W; G2: Er,Cr:YSGG laser, 1.0 W; G3: Er,Cr:YSGG laser, 1.5 W; G4: Er,Cr:YSGG laser, 2.0 W; G5: Er,Cr:YSGG laser, 2.5 W; G6: Er,Cr:YSGG laser, 3.0 W; G7: scaling and root planning (SRP) with manual curettes. The root surfaces irradiated by Er,Cr:YSGG at 1.0 W and scaling with manual curettes presented the highest degrees of ABC. The samples irradiated by the Er,Cr:YSGG laser were rougher than the samples treated by the manual curette, and increasing the laser power parameters caused more root wear and greater roughness on the root surface. The Er,Cr:YSGG laser is safe to use for periodontal treatment, but it is not appropriate to use irradiation greater than 1.0 W for this purpose. Microsc. Res. Tech. 78:529–535, 2015. © 2015 Wiley Periodicals, Inc.     

Does laser etching have an effect on application mode of a universal adhesive?—A microleakage and scanning electron microscopy evaluation

This study aimed to evaluate the microleakage of a universal adhesive's different application modes incorporated with Er,Cr:YSGG laser on Class V resin composite restorations. Sound human molar teeth (n = 30) were used for microleakage evaluations. Specimens with 60 standardized Class V cavities were divided into five groups according to the adhesive modes of universal adhesive, Adhese Universal (n = 12). Group 1‐etch‐and‐rinse mode with phosphoric acid; Group 2‐etch‐and‐rinse mode with Er,Cr:YSGG laser; Group 3‐selective‐etch mode with phosphoric acid; Group 4‐selective‐etch mode with Er,Cr:YSGG laser; Group 5‐self‐etch. After restorations were performed with a resin composite, Tetric N‐Ceram, the specimens were polished and subjected to thermocycling (10,000X). Following immersion in 0.5% basic fuschin for a day, the teeth were sectioned and the degree of microleakage was determined along the tooth‐resin composite interface using a light microscopy(40X). Five specimens from each group were examined by scanning electron microscopy. The Kruskal–Wallis, Siegel Castello, and Wilcoxon tests were used for statistical analyses (α = .05). At the enamel margins, significant differences were obtained among the groups (p < .05). Significantly higher microleakage scores were detected in Group 5 in comparison with Groups 1, 2, and 3. There were no significant differences between different adhesive strategies at the dentin margins (p > .05). While analyzing enamel and dentin microleakage scores, no statistically significant differences were observed in Groups 4 and 5 (p > .05). The laser application time and the adhesive modes of universal adhesives could affect the microleakage at the enamel margins. Different adhesive modes of universal adhesives combined with laser etching had no influence on the microleakage scores of dentin margins.     

Thermal,morphological, and spectral changes after Er,Cr:YSGG laser irradiation at low fluences on primary teeth for caries prevention

The aim of this study was to determine the temperature increase in the pulp chamber and possible thermal effects on molecular structure of primary teeth during the irradiation with Er,Cr:YSGG laser. Primary central incisors were divided into three groups (n = 20). Labial surfaces in each group were irradiated by Er,Cr:YSGG laser within different power and frequencies as following groups: I: 0.25 W, 20 Hz, II: 0.50 W, 20 Hz, III: 0.75 W, 20 Hz. A thermocouple was placed inside the pulp chamber so that the temperature increments were recorded during the enamel irradiation. Morphological changes of enamel surfaces were experimentally evaluated by SEM. Fourier‐transform infrared spectroscopy and RAMAN analyses were carried out to determine the differentiations in the molecular structure. The experimental results obtained were analyzed statistically by means of one‐way analysis of variance. Statistically significant differences were detected between groups (p < .05). Group III exhibited the highest values for the temperature parameters. Besides, the conical craters, cracks, and formation of ablation areas were observed for all the groups. Also, it was obtained that the hydroxyapatite lost the hydroxyl ions due to the thermal effect of the laser. Temperature rise throughout the Er,Cr:YSGG laser irradiation for prevention of primary enamel demineralization presented a positive correlation with the laser output power level. The formations of adverse morphological and spectral changes were detected on the surface of teeth after the laser application. On this basis, the Er,Cr:YSGG laser applications should be treated with much more caution considering enamel surface and pulpal tissues in primary teeth.     

Evaluation of fibroblast attachment in root conditioning with Er,Cr:YSGG laser versus EDTA: A SEM study

The regeneration of periodontal support is a main concern in periodontal therapy. This study aims to investigate the efficacy of Er, Cr:YSGG laser and EDTA based conditioning in attachment of fibroblast on root surfaces. This in vitro study was conducted on 81 root plates (6 mm × 4 mm × 1 mm) prepared from 27 single‐rooted human mature teeth. The samples were divided into three groups: (1) Er, Cr: YSGG laser conditioning with a G6 tip (2.78 µm, 0.75 W, pulse duration of 140 µs, repetition rate of 20 Hz) for 5–7 s; (2) EDTA conditioning (17%, pH: 8) for 1 min; and (3) the control group which were exposed neither to EDTA nor laser. The viability and proliferation rates assessments were performed using MTT assay on days 3 and 5. In addition, the level of cell attachment was studied using scanning electron microscopy. The data indicated Er, Cr:YSGG conditioning increased cell viability by lapse of time (from days 3–5), with significantly better cell attachment compared to the other groups on days 3 and 5 (P < 0.05). In addition, increasing cell attachment in the EDTA conditioning group compared with the control group was statistically significant on day 5 but not on day 3 (P < 0.05). In conclusion, Er, Cr:YSGG laser conditioning can promote enhance fibroblast attachment on dentinal root surfaces more than EDTA. Microsc. Res. Tech. 78:317–322, 2015. © 2015 Wiley Periodicals, Inc.     

Peracetic acid as a single endodontic irrigant: effects on microhardness,roughness and erosion of root canal dentin

The aim was to assess the effects of 1% peracetic acid (PAA) as a single endodontic irrigant on microhardness, roughness, and erosion of root canal dentin, compared with 2.5% sodium hypochlorite (NaOCl) and with 2.5% NaOCl combined with 17% EDTA. Forty human, single‐rooted tooth hemisections were submitted to Knoop microhardness test, before and after the following irrigation protocols: PAA = 1% PAA; NaOCl = 2.5% NaOCl; NaOCl‐EDTA‐NaOCl = 2.5% NaOCl +17% EDTA +2.5% NaOCl; and SS = saline. Another 40 roots were instrumented, irrigated with the same protocols, and sectioned longitudinally. The roughness analysis was performed on the mesial section using a confocal laser scanning microscope, whereas erosion was analyzed on each third of the distal section, using a scanning electron microscope. The data were analyzed using ANOVA and Tukey post‐tests, and Kruskal‐Wallis and Dunn post‐tests (α = .05). The PAA and NaOCl‐EDTA‐NaOCl groups showed no significant differences (p > .05); both promoted reduction in microhardness and increase in roughness, compared with the NaOCl and SS groups (p < .05). NaOCl‐EDTA‐NaOCl promoted higher erosion in the cervical and middle thirds than the other groups (p < .05); there was no difference among PAA, NaOCl, and SS (p > .05). There was also no difference among the groups regarding the apical third (p > .05). PAA used as a single endodontic irrigant caused reduction in root canal dentin microhardness and increase in roughness in a similar way to NaOCl‐EDTA‐NaOCl; however, PAA caused less erosion than NaOCl‐EDTA‐NaOCl.     

Bonding performance of universal adhesives to er,cr:YSGG laser‐irradiated enamel

Universal adhesives have been recently introduced for use as self‐etch or etch‐and‐rinse adhesives depending on the dental substrate and clinical condition. However, their bonding effectiveness to laser‐irradiated enamel is still not well‐known. Thus, the aim of this study was to compare the shear bond strength (SBS) of universal adhesives (Single Bond Universal; Nova Compo‐B Plus) applied to Er,Cr:YSGG laser‐irradiated enamel with SBS of the same adhesives applied in self‐etch and acid‐etching modes, respectively. Crown segments of sixty bovine incisors were embedded into standardized acrylic blocks. Flattened enamel surfaces were prepared. Specimens were divided into six groups according to universal adhesives and application modes randomly (n = 10), as follows: Single Bond Universal/acid‐etching mode; Nova Compo‐B Plus/acid‐etching mode; Single Bond Universal/self‐etching mode; Nova Compo‐B Plus/self‐etching mode; and Single Bond Universal/Er,Cr:YSGG Laser‐etching mode; Nova Compo‐B Plus/Er,Cr:YSGG Laser‐etching mode. After surface treatments, universal adhesives were applied onto surfaces. SBS was determined after storage in water for 24 h using a universal testing machine with a crosshead speed of 0.5 mm min^?1. Failure modes were evaluated using a stereomicroscope. Data was analyzed using two‐way of analyses of variances (ANOVA) (p = 0.05). Two‐way ANOVA revealed that adhesive had no effect on SBS (p = 0.88), but application mode significantly influenced SBS (p = 0.00). Acid‐etching significantly increased SBS, whereas there are no significant differences between self‐etch mode and laser‐etching for both adhesives. The bond strength of universal adhesives may depend on application mode. Acid etching may significantly increase bond strength, while laser etching may provide similar bond strength when compared to self‐etch mode.     

Persistence of endodontic methacrylate-based cement residues on dentin adhesive surface treated with different chemical removal protocols

The aim of this study was to evaluate the persistence of methacrylate‐based cement residues on the dentin, after dentin surface cleaning with ethanol or acetone, with or without previous application of a dentin adhesive. Forty bovine crown fragments were obtained and the dentin surface was washed with 1.0 mL of 2.5% sodium hypochlorite (NaOCl), followed by 0.1 mL of 17% ethylenediaminetetraacetic acid application for 3 min, and final irrigation with 2.5% NaOCl. The specimens were air dried and resin‐based cement was rubbed onto the dentine surface with a microbrush applicator. In 20 specimens, previously to cement, a dentin adhesive was applied in all surfaces. After 15 min, the surface was scrubbed with a cotton pellet and moistened with ethanol or acetone, compounding the following groups: G1—99.5% ethanol and G2—acetone, without previous use of dentin adhesive; G3—99.5% ethanol and G4—acetone, with previous use of dentin adhesive. The dentin surface was scrubbed until the cement residues could not be visually detected. Sections were then processed for scanning electron microscopy and evaluated at 500× magnification and scores were attributed to each image according to the area covered by residual sealer, and data were subjected to Kruskal–Wallis at 5% significance. The lower residue presence was observed in G3 (P = 0.005). All surface presented cement residues when acetone was used as cleaning solution (P = 0.0005). The cleaning solutions were unable to completely remove the cement residues from both surfaces. The ethanol used after previous application of the dentin adhesive promoted the lower presence of residues. Microsc. Res. Tech. 2012. © 2012 Wiley Periodicals, Inc.     

Evaluation of microleakage in class v cavities prepared by different caries removal methods

The purpose of this study was to comparatively evaluate the effects of different caries removal methods on microleakage success of class V adhesive restorations by means of light microscopy (stereomicroscope) and scanning electron microscopy (SEM) observations. Sixty‐four human teeth with class V caries that measured with DIAGNOdent were used. The samples were divided into four groups (n = 16) randomly according to caries removing methods of conventional method, Carisolv, Papacarie, and Er,Cr:YSGG laser system. The self‐etch Clearf?l SE Bond and Clearf?l Majesty Es‐II were used as restoration materials. After thermal cycles of 2,000 (5 and 55°C) samples were immersed in a 50% wt/wt AgNO_3. Samples were finally imaged and scored under light microscopy and SEM, respectively. The data were statistically analyzed using Kruskal–Wallis H, pairwise comparison and Wilcoxon's T tests at 5% significance level (p < .05). Statistical analysis demonstrated that there was no significant difference between microleakage scores in dentin regions but there were significant difference between the Papacarie and Er,Cr:YSGGlaser in terms of leakage scores in enamel sites. No statistically significant difference in leakage scores emerged between light microscopy and SEM.     

Micromorphology analysis and bond strength of two adhesives to Er,Cr:YSGG laser‐prepared vs. Bur‐prepared fluorosed enamel

Preservation of enamel during composite veneer restorations of fluorosed teeth could be achieved by conservative preparation with Erbium lasers. This study evaluated the effect of fluorosed enamel preparation with Er,Cr:YSGG vs. conventional diamond bur on the micromorphology and bond strength of a self‐etch and an etch‐and‐rinse adhesives. Er,Cr:YSGG laser or diamond bur preparation was performed on the flattened midbuccal surfaces of 70 extracted human premolars with moderate fluorosis (according to Thylstrup and Fejerskov index, TFI = 4–6). Adper Single Bond (SB) with acid etching for 20 or 40 s and Clearfil SE Bond (SEB) alone or with additional etching was applied in four laser groups. The same adhesive procedures were used in three bur groups except for 40 s of etching along with SB. After restoration, microshear bond strength was measured (MPa). Data were analyzed using ANOVA and Tamhane tests (α = 0.05). Six additional specimens were differently prepared and conditioned for scanning electron microscopy evaluation. The highest and lowest bond strengths were obtained for bur‐prepared/SB (39.5) and laser‐prepared/SEB (16.9), respectively, with a significant difference (P = 0.001). The different adhesive procedures used associated to two adhesives exhibited insignificantly lower bonding in laser‐prepared groups compared to bur‐prepared ones (P > 0.05), with the exception of additional etching/SEB, which bonded significantly higher to bur‐prepared (36.4) than to laser‐prepared enamel (18.7, P = 0.04). Morphological analyses revealed a delicate etch pattern with exposed enamel prisms on laser‐prepared fluorosed enamel after acid etching and less microretentive pattern after self‐etching primer. The etch‐and‐rinse adhesive was preferred in the laser‐prepared fluorosed enamel in terms of bonding performance. Microsc. Res. Tech. 77:779–784, 2014. © 2014 Wiley Periodicals, Inc.     

Effect of EDTA,sodium, and calcium hypochlorite on the inorganic component of root canal dentin: A SEM analysis

This study evaluated the influence of canal irrigation protocols with 5.25% calcium hypochlorite [Ca(OCl)₂], 5.25% sodium hypochlorite (NaOCl) and 17% EDTA solution on the inorganic component of root canal dentin. Sixty roots were randomly divided into six groups (n = 10): Saline solution (SS) (control); Saline solution (SSE) +17% EDTA; CH ? 5.25% Ca(OCl)₂; CHE ? 5.25% Ca(OCl)₂ + 17% EDTA; SH ? 5.25% NaOCl; SHE ? 5.25% NaOCl +17% EDTA. After canal irrigation, the specimens were longitudinally split and analyzed by scanning electron microscopy (SEM). Dentinal tubules were observed in transverse (middle and apical thirds) direction. The images were classified in scores, according to smear layer removal and peritubular dentin alteration, and data were analyzed by Kruskal–Wallis's test, followed by Dunn's test (α = 0.05). In the middle third, all groups with EDTA presented better removal of the smear layer with higher peritubular dentin alteration (p < .05). In the apical third, this happened only in SHE (p < .05). Ca(OCl)₂ and NaOCl exhibit similar performance to remove smear layer and alteration of the inorganic component in the middle third. In the apical third, NaOCl associated with EDTA showed better performance in smear layer removal.     

Microscopic analysis of the quality of obturation and physical properties of MTA Fillapex

This study analyzed the quality of obturation and physical properties of MTA Fillapex and AH Plus sealer. A sample of 30 human maxillary central incisors were instrumented with Protaper until a F5 (50/05) file. Both sealers were mixed with Rhodamine‐B dye to allow visualization on a confocal laser‐scanning microscope (CLSM). Next, the canals were filled using the single cone technique. After setting, all samples were sectioned at 2, 4, and 6 mm from the apex. CLSM was used to analyze the gaps and sealer penetration into the dentinal tubules. All samples were scanned 10 µm below the dentin surface and images were recorded at 100× magnification using the fluorescent mode. Additionally, the solubility, flowability and setting time of the sealers were evaluated. All the measured quantities of the examined materials were evaluated for significant differences by means of statistical analysis. The CLSM analysis of the MTA Fillapex showed the highest percentage of gaps at all sections (P = 0.0001). Physical tests revealed adequate properties for both sealers except for a higher solubility of the MTA Fillapex (P = 0.0001). The MTA Fillapex presented flowability and intratubular penetration similar to the AH Plus. Nevertheless, the MTA Fillapex sealer presented a higher solubility and considerable quantity of gaps between the sealer/dentin interface in relation to the AH Plus sealer. Clinicians must take into consideration, the quality of endodontic sealers as it is essential in the outcome of the root canal filling. Microsc. Res. Tech. 77:1031–1036, 2014. © 2014 Wiley Periodicals, Inc.     

Influence of chlorhexidine on dentin adhesive interface micromorphology and nanoleakage expression of resin cements

This study focused on adhesive interface morphologic characterization and nanoleakage expression of resin cements bonded to human dentin pretreated with 1% chlorhexidine (CHX). Thirty‐two non‐carious human third molars were ground flat to expose superficial dentin. Resin composite blocks were luted to the exposed dentin using one conventional (RelyX ARC) and one self‐adhesive resin cement (RelyX U100), with/without CHX pretreatment. Four groups (n = 8) were obtained: control groups (ARC and U100); experimental groups (ARC/CHX and U100/CHX) were pretreated with 1% CHX prior to the luting process. After storage in water for 24 h, the bonded teeth were sectioned into 0.9 × 0.9 mm² sticks producing a minimum of 12 sticks per tooth. Four sticks from each tooth were prepared for hybrid layer evaluation by scanning electron microscope analysis. The remaining sticks were immersed in silver nitrate for 24 h for either nanoleakage evaluation along the bonded interfaces or after rupture. Nanoleakage samples were carbon coated and examined using backscattered electron mode. Well‐established hybrid layers were observed in the groups luted with RelyX ARC. Nanoleakage evaluation revealed increase nanoleakage in groups treated with CHX for both resin cements. Group U100/CHX exhibited the most pronouncing nanoleakage expression along with porous zones adjacent to the CHX pretreated dentin. The results suggest a possible incompatibility between CHX and RelyX U100 that raises the concern that the use of CHX with self‐adhesive cements may adversely affect resin‐dentin bond. Microsc. Res. Tech. 76:788–794, 2013. © 2013 Wiley Periodicals, Inc.     

Evaluation of epoxy resin sealer after three root canal filling techniques by confocal laser scanning microscopy

The aim of this study was to evaluate the penetration of endodontic sealer into the dentin tubules, the integrity of the sealer layer perimeter, and the sealer area at the apical third after different filling techniques by confocal laser scanning microscopy (CLSM). Forty‐five mandibular premolars were mechanically prepared with ProTaper files, until F5 file. Thereafter, they were filled with an epoxy‐resin sealer (AH Plus) mixed with Rhodamine B dye (0.1% proportion) and allocated in three groups: Group 1, single master cone; Group 2, cold lateral compaction; and Group 3, Thermafil. For confocal laser scanning microscopy analysis, the specimens were transversely sectioned at 4 mm from the apex. The images at ×10 and ×40 were analyzed by Imagetool 3.0 software. Significant differences were not found among the three experimental groups according the dentin‐impregnate area by the sealer (P = 0.68) and between the sealer and root canal perimeter (P = 0.18). However, root canal filling techniques were significantly different when apical sealer areas were compared (P = 0.001). Thermafil group showed smaller sealer areas (8.09%) while cold lateral compaction and gutta‐percha master cone showed similar areas (17.37 and 21.18%, respectively). The dentin‐impregnated area was not dependent on the root canal filling technique. Single master cone, cold lateral condensation and Thermafil techniques presented integrity of the sealer perimeter close to 100% and Thermafil resulted in a significantly thinner sealer layer. Microsc. Res. Tech. 75:1277–1280, 2012. © 2012 Wiley Periodicals, Inc.     

Analysis of the interfacial micromorphology of adhesive systems in cavities prepared with Er,Cr:YSGG, Er:YAG laser and bur

The purpose of this in vitro study was to evaluate the interaction pattern of adhesive systems on laser and bur cavities. Cavities were prepared according to the following groups (n=9): (G1) conventional diamond bur (No. 1013); (G2) Er:YAG laser (250 mJ, 4 Hz, 80.6 J/cm2); (G3) Er,Cr:YSGG laser (3.5 W, 20 Hz, 61.7 J/cm2). After cavity preparation, specimens were divided into three subgroups differing the adhesive systems used (n=3): (GA) AdheSE; (GB) Clearfil standard error (SE) Bond; (GC) Single Bond. After insertion of a micro-hybrid composite resin, the specimens were sectioned across the bonded surface dividing the teeth into two halves, which were prepared for SEM analysis. Cavities prepared with laser appeared to be more irregular than the bur cavities. Different patterns of gap formation and resin tags could be observed, showing the differences, advantages, and disadvantages of both types of cavities. Under the settings of the present study, resin tags were more pronounced in lased dentin than bur prepared dentin independently of the bonding systems used. On the other hand gap formation between dentin and resin in laser prepared cavities was observed suggesting collagen alteration.     

Penetrability of AH plus and MTA fillapex after endodontic treatment and retreatment: A confocal laser scanning microscopy study

The aim of the study was to assess the penetrability of two endodontic sealers (AH Plus and MTA Fillapex) into dentinal tubules, submitted to endodontic treatment and subsequently to endodontic retreatment. Thirty ex vivo incisors were prepared using ProTaper rotary system up to F3 instrument and divided in three groups according to the endodontic sealer used for root canal filling: AH Plus (AHP), MTA Fillapex (MTAF), and control group (CG) without using EDTA previously to the root canal filling. Rhodamine B dye (red) was incorporated to the sealers in order to provide the fluorescence which will enable confocal laser scanning microscopy (CLSM) assessment. All specimens were filled with gutta‐percha cones using the lateral compaction technique. The specimens were submitted to endodontic retreatment using ProTaper Retreatment system, re‐prepared up to F5 instruments and filled with gutta‐percha cones and the same sealer used during endodontic retreatment. Fluorescein dye (green) was incorporated to the sealer in order to distinguish from the first filling. The roots were sectioned 2 mm from the apex and assessed by CLSM. No difference was found between the two experimental groups (P > 0.05). On the other hand, in the control group the sealers were not capable to penetrate into dentinal tubules after endodontic treatment (P > 0.05). In retreatment cases, none of the sealers were able to penetrate into dentin tubules. It can be concluded that sealer penetrability is high during endodontic treatment. However, MTA Fillapex and AH Plus do not penetrate into dentinal tubules after endodontic retreatment. Microsc. Res. Tech. 77:467–471, 2014. © 2014 Wiley Periodicals, Inc.     

Response of E. faecalis biofilms to different associations of auxiliary substances during root canal preparation: A confocal laser microscopy analysis

Objective: This in vitro study evaluated the effect of different endodontic auxiliary chemical substances over Enterococcus faecalis (Ef) biofilm through confocal laser scanning microscopy (CLSM). Methods: Forty‐five bovine incisors were infected with Ef for 21 days. Teeth were divided into five groups: group 1: 2.5% NaOCl + EDTA, group 2: 2% CHX gel + EDTA, group 3: 2% CHX liquid + EDTA, group 4: 2.5% NaOCl + 2% CHX gel + EDTA, group 5: 2.5% NaOCl + 2% CHX liquid + EDTA and a negative and a positive control group (NCG; PCG). The samples were stained with SYTO9 and propidium iodide and analyzed by CLSM. Bacterial viability was quantitatively analyzed by the proportions of dead and live bacteria in the biofilm remnants. Scores were standardized according to the total bacterial load (TBL)—1: ≤25%, 2: >25 ≤50%, 3: >50 ≤75%, 4: >75% and debris—1: absence of debris; 2: presence of debris. Statistical analysis was carried out through the Kruskal–Wallis and the Fischer exact tests (P = 0.05). Results: No statistical differences were observed to CFU, debris and bacterial viability. Conclusion: None of the tested substances could completely eliminate Ef from the root canal space. Microsc. Res. Tech. 76:658–662, 2013. © 2013 Wiley Periodicals, Inc.     

The effectiveness of glass ionomer cement as a fiber post cementation system in endodontically treated teeth

This study compared the performance of a glass ionomer (GC Gold Label 1, GIC) as a fiber post cementation system for glass fiber posts with a self‐adhesive resin cement (Relyx U200, RUC) and a conventional resin cement system (Scotchbond Muli‐Purpose and Relyx ARC, RAC). Thirty endodontically treated canines were randomly divided in three groups (n = 10), according to the fiber post cementation system: (RAC)—Scotchbond Multi‐Purpose and Relyx X ARC; (RUC)—Relyx U200 and (GIC)—GC Gold Label 1 Luting & Lining. Rhodamine was incorporated into the cementation system prior to the fiber post cementation. After glass fiber post cementation, roots were incubated in artificial saliva for 6 months. After that, specimens from the cervical, middle, and apical thirds of the post space were prepared and analyzed using a push‐out bond strength test and confocal laser microscopy. ANOVA one way and Tukey tests showed that GIC and RUC demonstrated similar push‐out bond strength values, independently of the post space third (p > .05); however, values were greater than those shown by RAC (p < .05). For dentin penetrability, GIC and RUC also had similar results (p > 0.05) and lower than RAC (p < 0.05). Inside the root canal, the cementation system using glass ionomer cement (GC Gold Label 1 Luting & Lining) has similar push‐out bond strength to the self‐adhesive resin cement (Relyx U200) and these were higher than the conventional resin (Relyx ARC), despite its higher dentin penetrability.     

Morphological alterations of radicular dentine pretreated with different irrigating solutions and irradiated with 980-nm diode laser

Background: The topographical features of intraradicular dentine pretreated with sodium hypochlorite (NaOCl) or ethylenediamine tetraacetic acid (EDTA) followed by diode laser irradiation have not yet been determined. Purpose: To evaluate the alterations of dentine irradiated with 980‐nm diode laser at different parameters after the surface treatment with NaOCl and EDTA. Study design: Roots of 60 canines were biomechanically prepared and irrigated with NaOCl or EDTA. Groups were divided according to the laser parameters: 1.5 W/CW; 1.5 W/100 Hz; 3.0 W/CW; 3.0 W/100 Hz and no irradiation (control). The roots were splited longitudinally and analyzed by scanning electron microscopy (SEM) in a quali‐quatitative way. The scores were submitted to two‐way Kruskal–Wallis and Dunn's tests. Results: The statistical analysis demonstrated that the specimens treated only with NaOCl or EDTA (control groups) were statistically different (P < 0.05) from the laser‐irradiated specimens, regardless of the parameter setting. The specimens treated with NaOCl showed a laser‐modified surface with smear layer, fissures, and no visible tubules. Those treated with EDTA and irradiated by laser presented absence of smear layer, tubules partially exposed and melting areas. Conclusions: The tested parameters of 980‐nm diode laser promoted similar alterations on dentine morphology, dependent to the type of surface pretreatment. Microsc. Res. Tech., 2009. © 2008 Wiley‐Liss, Inc.     

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 (μTBS) 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 μTBS testing. ANOVA (α = 5%) revealed that G1 presented the highest μTBS 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.