Antimicrobial activity of intracanal medications against both Enterococcus faecalis and Candida albicans biofilm

Enterococcus faecalis and Candida albicans have been associated with cases of secondary and persistent root canal infections, been resistant to calcium hydroxide. So, the evaluation of the susceptibility of these microorganisms biofilms to new drugs is an important practice for establishing the best drug and consequently success of treatment. For this, in vitro biofilm formation of E. faecalis and C. albicans was induced separately on blocks obtained from bovine teeth. After the period of specimen incubation for biofilm maturation, the samples were immersed in the pastes: 1 – calcium hydroxide (CH), 2 – chlorhexidine (C), 3 – ciprofloxacin (CP), 4 – metronidazole (MT), 5 – ketoconazole (KE), 6 – double antibiotic (DB), 7 – triple antibiotic (TA), 8 – ciprofloxacin + ketoconazole (CPKE); 9 – ciprofloxacin + metronidazole + ketoconazole (CPMTKE), 10 – metronidazole + ketoconazole (MTKE), and 11 – control (CO) for 7 days. Next, the specimens were live/dead stained for analysis by confocal microscopy. By means of the Bioimage program, the biovolume and percentage of live cells were measured. The data were statistically compared (p = .05). For the C. albicans biofilm, the best antimicrobial action was found for MTKE, CPKE, and MT groups. Whereas for E. faecalis biofilm, the lowest percentage of live bacteria was found in TA, DB, and CP groups; however, KE, CPKE, CPMTKE, and MTKE groups shown to be effective. The authors concluded calcium hydroxide paste and chlorhexidine was not effective for both biofilms. The MTKE and CPKE pastes presented effectiveness for both biofilms. TA and DB pastes were effective just in the E. faecalis biofilms.     

Antibacterial activity of chlorhexidine after final irrigation with ethanol: CLSM and culture‐based method analysis

This study investigated the effect of 95% ethanol on the antibacterial properties of 2% chlorexidine (CHX) over monospecies biofilm (Enterococcus faecalis) through a culture‐based method, and over multispecies biofilm using confocal laser scanning microscopy (CLSM). For monospecies model, E. faecalis biofilm was induced in 40 root canals. The irrigation procedures were: S—saline solution; S/CHX—saline solution + CHX; E—ethanol; and E/CHX—ethanol + CHX. Microbial sampling was performed at three periods: before (S1), immediately after (S2), and 72 h after the final flush (S3). For multispecies biofilm model, 28 sterilized bovine dentin blocks were fixed on a removable orthodontic device to allow intraoral biofilm development. Seven samples were used in each group. Statistical analysis was carried out by using the Kruskal–Wallis test and Dunn's test for multiple comparisons. There was a significant reduction in CFUs count immediately after the final flush (S2) in all experimental groups (P < 0.05). However, only S/CHX, E and E/CHX groups had CFU counts close to zero, without differences among them (P > 0.05). After 72h (S3), the S/CHX and E/CHX groups had CFU counts near zero (P > 0.05). The CFU count increased in S3 for S and E groups (P < 0.05). CLSM showed that the percentages of remaining live cells were similar in S/CHX, E, and E/CHX groups (P > 0.05). The S group had the highest percentage of live cells (P < 0.05). The 95% ethanol did not interfere in the antibacterial properties of 2% CHX over mono‐ and multispecies biofilms. Microsc. Res. Tech. 78:682–687, 2015. © 2015 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.     

Effect of medicaments used in endodontic regeneration on the morphological characteristics of bovine radicular dentin: Experimental immature tooth model

The purpose of this study was to evaluate the effect of different combinations of irrigating solutions and intracanal dressings in the pretreatment of bovine radicular dentin, using an experimental immature tooth model. Eighty healthy bovine teeth, simulated with incomplete rhizogenesis, were randomly distributed according to the protocols of root canal dentin pretreatment for a regenerative endodontic procedure (n = 10): Control (irrigation with distilled water); SH (irrigation with 1.5% Sodium Hypochlorite); EDTA (irrigation with 17% EDTA); SH/EDTA (irrigation with 1.5% SH + 17% EDTA); SH/CH/EDTA (irrigation with 1.5% SH + calcium hydroxide paste +17% EDTA); SH/MTAP/EDTA (irrigation with 1.5% SH + modified triple antibiotic paste + EDTA 17%); SH/TAP/EDTA (irrigation with 1.5% SH + triple antibiotic paste +17% EDTA) and SH/DAP/EDTA (irrigation with 1.5% SH + double antibiotic paste + EDTA 17%). After the completion of the protocol, the demineralization, the exposure of collagen fibers, and the dentin erosion was evaluated under scanning electron microscopy (SEM), by applying a score system (1–3) to classify the observed features. Statistical analysis was performed (Kruskal‐Wallis and Dunn Multiple Comparison tests—p < .05). SH/TAP/EDTA and SH/DAP/EDTA groups presented the highest rates of demineralization in both the coronal and middle thirds of the root (p < .05). In the SH/MTAP/EDTA group, the samples presented moderate demineralization. The samples from the SH/CH/EDTA group presented similar findings to the control group (p < .05). Conventional triple antibiotic (TAP) and double antibiotic (DAP) pastes promoted more pronounced morphological changes on the dentin surface.     

Computed microtomography evaluation of calcium hydroxide‐based root canal dressing removal from oval root canals by different methods of irrigation

The aim of this study was to evaluate the capacity of conventional irrigation, passive ultrasonic irrigation (PUI), and Easy Clean for removing calcium hydroxide‐based root canal dressing from oval root canals. Thirty mandibular uniradicular incisors with oval canals were used, and subjected to chemical–mechanical preparation with Reciproc R40 instruments. The main canal was filled with a paste based on Ca(OH)₂ P.A., iodoform and propylene glycol in the ratio of 3:1:1. The teeth were stored in 100% humidity at a temperature of 37°C for 14 days. Afterwards, the teeth were divided into three groups (n = 10) according to the method of irrigation used (conventional irrigation, PUI, and Easy Clean). The specimens were analyzed by computed microtomography at three time intervals: before placing the root canal dressing, with the root canal dressing in place, and after application of the irrigation methods for removing it. The data were submitted to Kruskal–Wallis and Dunn tests for analyzing the canal as a whole, and Friedman and Dunn for analyzing the root thirds. The results showed that conventional irrigation was less efficient for removing the root canal dressing in comparison with the methods that agitated the irrigant solution (p < .05). When the root canal was analyzed as a whole, Easy Clean, and PUI were similar (p > .05). In analysis of the thirds, Easy Clean was more efficient than conventional irrigation in all the thirds, while PUI showed this behavior only in the cervical third (p < .05). The authors concluded that in oval canals, none of the irrigation methods were capable of removing all the root canal dressing, however, the methods that agitated the irrigant solution were more efficient than conventional irrigation.     

Effect of final irrigation protocols on microhardness and erosion of root canal dentin

The aim of this study was to evaluate the effect of final irrigation protocols (17% EDTA, BioPure MTAD, SmearClear, and QMiX) on microhardness and erosion of root canal dentin. Fifty roots were sectioned transversely at the cement–enamel junction and each root was sectioned horizontally into 4‐mm‐thick slices. The samples were divided into five groups (n = 10) according to the final irrigation protocol: G1: distilled water (control group); G2: 17% EDTA; G3: BioPure MTAD; G4: SmearClear; and G5: QMiX. The dentin microhardness was then measured with a load of 25 g for 10 s. Initially, the reference microhardness values were obtained for the samples without any etching. The same samples were then submitted to the final irrigation protocols. A new measure was realized and the difference between before and after the procedures was the dentin microhardness reduction. In sequence, the specimens were submitted to SEM analysis to verify the dentinal erosion. The Kruskal Wallis and Dunn tests (α = 5%) were used to compare the results. The dentin microhardness decreased for all final irrigation protocols. There was no significant difference between groups 2, 3, 4, and 5 (P > 0.05), but this groups presented significant dentin microhardness reduction than G1 (P < 0.05). In G2, occurred the highest incidence of dentinal erosion (P < 0.05). 17% EDTA, BioPure MTAD, SmearClear, and QMiX promoted significant dentin microhardness reduction. Dentinal tubules erosion was promoted by 17% EDTA. Microsc. Res. Tech., 76:1079–1083, 2013. © 2013 Wiley Periodicals, Inc.     

Effects of chemical agents on physical properties and structure of primary pulp chamber dentin

This study evaluated the effects of chemical agents on the physical properties and structure of primary pulp chamber dentin using surface roughness, microhardness tests, and scanning electron microscopy (SEM). Twenty‐five primary teeth were sectioned exposing the pulp chamber and were divided into five groups (n = 5): NT, no treatment; SH1, 1% sodium hypochlorite (NaOCl); SH1U, 1% NaOCl + Endo‐PTC^®; SH1E, 1% NaOCl + 17% EDTA; and E, 17% EDTA. After dentin treatment, the specimens were submitted to roughness, microhardness testing, and SEM analysis. Roughness and microhardness data were submitted to one‐way ANOVA and Tukey's test (P < 0.05). The SH1E group showed the highest roughness, followed by the E group (P < 0.05) when compared with the NT, SH1, and SH1U groups. Microhardness values of SH1 and SH1U showed no significant difference as compared to the NT (control) group (P > 0.05). Microhardness values could not be obtained in the EDTA groups (SH1E and E). The presence of intertubular dentin with opened dentin tubules was observed in the NT, SH1, and SH1U groups. SH1E showed eroded and disorganized dentin with few opened tubules and the intertubular/peritubular dentin was partially removed. Considering the physical and structural approaches and the chemical agents studied, it can be concluded that NaOCl and NaOCl associated with Endo‐PTC^® were the agents that promoted the smallest changes in surface roughness, microhardness, and structure of the pulp chamber dentin of primary teeth. Microsc. Res. Tech. 77:52–56, 2014. © 2013 Wiley Periodicals, Inc.     

Effect of ethanol on the antimicrobial properties of chlorhexidine over oral biofilm

The aim of this study was to evaluate the effect of 95% ethanol irrigation, with 5 or 10 min of action, on the antibacterial properties of 2% chlorhexidine (CHX), on oral biofilm, evaluated with confocal laser scanning microscopy (CLSM). Oral biofilm development was induced in 80 sterilized bovine dentin blocks, distributed in two groups (5 or 10 min) and 4 subgroups, according to time and the solution used: Saline (SALINE5, SALINE10); Saline followed by CHX (SALINE/CHX5, SALINE/CHX10); Ethanol (ETHANOL5, ETHANOL10), Ethanol followed by CHX (ETHANOL/CHX5, ETHANOL/CHX10). The surface of the block was dyed with Live/Dead^® BacLight. Images from different areas were analyzed by BioImage L program. The total biovolum (µm³), biovolum of live cells (green), percentage of live cells of the thickness of the biofilm visualized in CLSM and on surface biofilm were evaluated. Total biovolum and biovolum of living cells showed similar results among the different groups (p > .05). The percentage of living cells in total thickness of the biofilm also was similar among the groups (p > .05), except ETHANOL5, SALINE/CHX10, ETHANOL10, and ETHANOL/CHX10 that showed lower percentage than SALINE5 (p < .05). The ETHANOL10 and ETHANOL/CHX10 also showed lower percentage of living cells than ETHANOL/CHX5 and SALINE10 (p < .05). In relation to biofilm surface, SALINE/CHX5, SALINE/CHX10, ETHANOL5, ETHANOL10, ETHANOL/CHX5, and ETHANOL/CHX10 showed a lower percentage of living cells percentage than SALINE5 and SALINE10 groups (p < .05). Therefore, ethanol has no effect on antimicrobial properties of 2% chlorhexidine, prior when used as endodontic irrigating solution.     

Dentin bond strength and nanoleakage of the adhesive interface after intracoronal bleaching

This study evaluated dentin bond strength (BS) and nanoleakage of non‐ and pre‐etched dentin immediately (T₀,), 7 days (T₇), and 14 days (T₁₄) after bleaching. Bovine incisors (150) were selected and half of them submitted to intrapulpal dentin etching (e). Non‐ and pre‐etched dentin were subjected to the following (n = 15): no bleaching/control (C); 35% carbamide peroxide (CP); 35% hydrogen peroxide (35% HP); 25% hydrogen peroxide (25% HP); and sodium perborate (SP). Bleaching agents were applied to the pulp chamber four times within a 72‐h interval. Afterwards, pulp chamber dentin was prepared for the BS test at different evaluation times (n = 5): T₀, T₇, and T₁₄. Composite blocks were built on pulp chamber and sectioned in slices. Slices were reduced to an hour‐glass shape with a cross‐sectional area of 0.8 mm² and submitted to microtensile BS test. Two additional specimens for each group were prepared for nanoleakage evaluation by transmission electron microscopy (TEM). Results were analyzed by ANOVA (two‐way) and Dunnett's test (p < .05). BS decreased immediately after intracoronal bleaching for both sound and pre‐etched dentin (p < .05). At T₁₄, the BS of non‐etched bleached dentin increased for all groups, whereas the pre‐etched SPe group presented BS similar to the Ce. Nanoleakage within the hybrid layer was perceptible immediately after bleaching, although a decrease in nanoleakage was observed for all groups at T₁₄. Adhesive restorations should be performed 7–14 days after bleaching, according to the bleaching agent used. Intracoronal bleaching should be performed preferably with sodium perborate if previous dentin etching is applied.     

Effect of in‐office bleaching with 35% hydrogen peroxide with and without addition of calcium on the enamel surface

This study aimed to evaluate effectiveness and effects of bleaching with 35% hydrogen peroxide with and without calcium on color, micromorphology, and the replacement of calcium and phosphate on the enamel surface. Thirty bovine enamel blocks (5.0 × 5.0 mm) were placed into the following groups: G1: artificial saliva (control); G2: 35% hydrogen peroxide gel without calcium (Whiteness HP Maxx–FGM); and G3: 35% hydrogen peroxide gel with calcium (Whiteness HP Blue–FGM). Three color measurements were performed with a spectrophotometer: untreated (baseline), after performing staining, and after application of bleaching agents. Calcium deposition on the enamel was evaluated before and after the application of bleaching agents using energy‐dispersive X‐ray spectrometry. The enamel surface micromorphology was observed under scanning electron microscopy. The pH of each product was measured. The data were subjected to one‐factor analysis of variance (ANOVA), and any differences were analyzed using Tukey's test (P < 0.05). G3 showed greater variation in total color after the experiment than G2 and G1; there was no significant difference in calcium or phosphorus concentration before and after the experimental procedures; morphological changes were observed only in G2 and G3; and the pH values of the Whiteness HP Maxx and Whiteness HP Blue bleaching agents were 5.77 and 7.79, respectively. The 35% hydrogen peroxide with calcium showed greater bleaching potential, but the addition of calcium had no effect in terms of reducing morphological changes or increasing the calcium concentration on the enamel surface. Microsc. Res. Tech. 78:975–981, 2015. © 2015 Wiley Periodicals, Inc.     

Effect of rotary instrument associated with different irrigation techniques on removing calcium hydroxide dressing

Calcium hydroxide [Ca(OH)₂] residues in root canals may compromise sealing of filling and endodontic treatment success. The aim of this study was to compare the efficacy of using rotary instrument associated with EndoActivator, EndoVac, passive ultrasonic irrigation (PUI), and conventional needle irrigation (CNI), in Ca(OH)₂ removal from root canal, by means of scanning electron microscopy (SEM) images. Sixty‐six human canines were prepared with the Protaper system up to F5 and filled with Ca(OH)₂. After 7 days, Ca(OH)₂ was removed with rotary instrument F5 associated with the irrigation techniques used in each group (n = 15): GI (CNI), GII (EndoVac), GIII (EndoActivator) and GIV (PUI). In all groups 15 mL of 2.5% NaOCl and 3 mL of 17% EDTA were used for Ca(OH)₂ removal. The Ca(OH)₂ residues was evaluated by SEM in the middle and apical third using a system of scores. The results were analyzed by the Kruskal‐Wallis and Dunn tests (α = 0.05). None of the techniques completely removed the Ca(OH)₂ from root canals. There was no difference between EndoActivator, EndoVac and PUI (P > 0.05), but the three techniques removed more Ca(OH)₂ than the CNI (P < 0,05), in the middle and apical thirds of the root canal. It was concluded that the rotary instrument combined with EndoActivator, EndoVac, and PUI was shown to be more efficient than the rotary instrument combined with the CNI in removing Ca(OH)₂ from the root canal. Microsc. Res. Tech. 77:642–646, 2014. © 2014 Wiley Periodicals, Inc.     

Genistein affects ovarian folliculogenesis: A stereological study

The effects of short‐term genistein exposure on ovarian folliculogenesis in immature rats were examined stereologically. To determine whether genistein acts as an estrogen agonist or antagonist, the results were compared with the effects of 17α‐ethynylestradiol. Immature female rats received 50 mg/kg/bw of genistein in dimethyl sulfoxide subcutaneously daily for three consecutive days from 18 to 20 days. The second group was injected with 1 μg/kg/bw of 17α‐ethynylestradiol in olive oil in the same schedule. Each group had a corresponding control. Genistein increased ovary and ovarian stroma volumes by 18.50% (P < 0.05) and 53.40% (P < 0.05), respectively, and changed the parenchyma to stroma ratio in favor of stroma. Genistein induced decreases in the number of primordial (by 17.23%; P < 0.05), primary (16.62%; P < 0.05), and secondary follicles (12.29%: P < 0.05), whereas the number of atretic secondary follicles increased (5.10‐fold; P < 0.05). The number of healthy large follicles was raised by 27.3% (P < 0.05), accompanied by 35.64% more atretic large follicles (P < 0.05). Similarly to genistein, estradiol changed the parenchyma to stroma ratio in favor of stroma, and reduced the number of primordial follicles, but the number of primary follicles was elevated. There were more healthy and atretic small and large follicles. In conclusion, genistein acted as an estrogen antagonist and had an inhibitory effect on the initial phase of folliculogenesis. In the other phases, genistein acted as an estrogen agonist, stimulating transition from the preantral to antral stage of folliculogenesis, and altering the ratio of follicular parenchyma and ovarian stroma in favor of stroma. Microsc. Res. Tech. 2012. © 2012 Wiley Periodicals, Inc.     

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.     

Investigation of mineral content of root canal dentin after the application of various antibiotic paste using energy‐dispersive X‐ray detector

The purpose of this study was to evaluate mineral content of root canal dentin after treatment with different antibiotic pastes including the mixture of metronidazole, ciprofloxacin, doxycycline, cefaclor, amoxicillin, or minocycline. Fifty extracted maxillary canine teeth were randomly divided into five groups (n = 10 teeth for each group). Root canals were prepared Reciproc rotary files. Canals were irrigated using 5 ml 5% NaOCl and 1 ml 15% EDTA. Each tooth in all groups were longitudinally splitted into two pieces as a control and experimental samples. Each experimental group received following antibiotic paste; double antibiotic paste (DAP) and triple antibiotic paste with doxycycline (TAPd), TAP with cefaclor (TAPc), TAP with amoxicillin (TAPa), and TAP with minocycline (TAPm) for 21 days. The Ca, P, Mg, Ca, and K levels, and the Ca/P ratio was analyzed by a scanning electron microscope (SEM) equipped using a Bruker energy‐dispersive X‐Ray (EDX) detector. Data were analyzed with independent samples t‐test, one‐way anova, and Duncan tests. Ca and Ca/P ratio showed a statistically significant increase TAP with amoxicillin and cefaclor (p < .05). DAP, TAPd, and TAPm did not change the mineral levels (p > .05). TAPa and TAPc with increased the Ca level and Ca/P ratio of the root canal dentin which consequently positively influences the revascularization process.     

Experimental study of influence of composition on radiopacity of fiber post materials

This experimental study aims to evaluate the radiopacity of various fiber post materials and to determine the effects of material composition as analyzed by energy‐dispersive X‐ray spectrophotometry (EDS; EDAX Team Software; EDAX, Inc., Mahwah, NJ) on radiopacity. Five specimens of seven fiber post materials with 2‐mm thickness were prepared and digital radiographs were taken with an aluminum stepwedge (SW) and 2‐mm‐thick tooth slice. The mean gray values (MGVs) of specimens were measured using the histogram function of a computer graphics program (Adobe Photoshop CS6; Adobe System, Inc., San Jose, CA). The MGVs of fiber post materials were compared with an aluminum SW and dentin of equal thickness. The fiber post specimens were examined by scanning electron microscopy and EDS analysis performed for the elementary analysis of material composition. The MGVs of fiber posts ranged between 83.67 ± 3.64 and 57.80 ± 7.08 pixels. Materials were sorted in descending order of MGV as follows: Reforpost, Carbopost, D.T. Light‐Post, Easypost, Glassix Radiopaque, Dentolic Glass Fiber Post, and RelyX Fiber Post. All fiber posts demonstrated significantly higher radiopacity values than 2‐mm‐thick aluminum (p < .05). EDS analysis results indicated that the evaluated fiber posts included various elements for radiopacity in different ratios. All tested fiber post materials showed radiopacity values above the minimum recommendations of the International Organization for Standardization. EDS analysis results indicated that each manufacturer used different compositions of elements like zirconium, barium, titanium, and iron for achieving radiopacity in materials.     

Remineralization effects of self-assembling peptide P11-4 associated with three materials on early enamel carious lesions: An in vitro study

The aim of this study was to assess the remineralization of enamel caries lesions using the self-assembling peptide P₁₁-4 associated with different materials. Artificial early enamel lesions were prepared on 154 primary teeth. The samples were randomly divided into eight groups: (1) control, (2) P₁₁-4, (3) fluoridate toothpaste (FT), (4) P₁₁-4 + FT, (5) casein phosphopeptide–amorphous calcium phosphate (CPP–ACP), (6) P₁₁-4 + CPP–ACP, (7) fluoridate bioactive glass toothpaste (BT), and (8) P₁₁-4 + BT. The surface enamel microhardness (EMH) and energy-dispersive X-ray spectroscopy (EDS) of the teeth were then measured at the baseline, after demineralization, and after 28 days of remineralization. The enamel surfaces were assessed by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The data were analyzed with one-way analysis of variance (ANOVA) (p < .05). EMH after demineralization was significantly lower than the baseline value (p < .001). The interventions led to an enhanced percentage of EMH recovery (%REMH), which was higher in Groups 6 and 7. There was no significant difference between Groups 3 and 4. Groups 1 and 2 had the lowest %REMH. The mean calcium/phosphate weight percentage ratio of P₁₁-4 was significantly lower than the others (p < .001). The FESEM and AFM images revealed mineral deposition on the eroded enamel and reductions in surface roughness in Groups 5 and 7.     

The use of an Er:YAG laser to remove demineralized dentin and its influence on dentin permeability

The purpose of this study was to analyze, correlate, and compare the demineralization and permeability of dentin remaining after caries removal with either an Er:YAG laser, a bur, or a curette. Thirty human dentin fragments were immersed in a demineralizing solution for 20 days and were randomly divided into three groups (n = 10) for the removal of the demineralized lesion. The groups were G1—Er:YAG laser (200 mJ/6 Hz; noncontact at 12 mm; spot: 0.63 mm), G2—Bur, and G3—Curette. The specimens were then immersed in a 10% copper sulfate solution, then in a 1% dithiooxamide alcoholic solution for 30 min and kept in ammonia vapor for 7 days. Next, the specimens were examined with optical microscopy. The amount of demineralized dentin and the level of copper ion infiltration in the dentin were quantified in μm using Axion Vision software. Data were analyzed with the Kruskal‐Wallis test (p < 0.05) and Pearson's Correlation test. The analysis revealed no significant differences between the three caries removal methods in terms of their capacity to remove demineralized tissue (G1: 10.6 μm; G2: 8.4 μm; G3: 11 μm), although the laser removal generated more tissue permeability than the others methods (G1: 17.6 μm; G2: 6.6 μm; G3: 5.5 μm). The correlation between the remaining demineralized dentin and the dentin permeability was moderate for the conventional methods and higher for the Er:YAG laser. It can therefore be concluded that the laser produced an increase in permeability that was directly proportional to the amount of demineralized tissue removal. Microsc. Res. Tech. 76:225–230, 2013. © 2012 Wiley Periodicals, Inc.     

Maternal dexamethasone treatment reduces ovarian follicle number in neonatal rat offspring

Elevated glucocorticoid levels in the gravid female circulation affect a number of endocrine functions in the fetuses and neonates. The aim of this study was to examine the effects of maternal dexamethasone (Dx) administration during late pregnancy on the ovaries of neonatal offspring. On the 16th day of pregnancy, experimental dams received subcutaneously 1.0 mg Dx/kg b.w., followed by 0.5 mg Dx/kg b.w./day on the 17th and 18th days of gestation. The control gravid females received the same volume of saline vehicle. Left ovaries from 5‐day‐old female pups were stereologically analyzed. The ovary volumes were estimated using Cavalieri's principle. The number of healthy and atretic primordial and primary follicles was estimated using a fractionator–physical disector method. The number of secondary follicles was determined by exact counts of every fourth section encompassing whole cross‐sections of the ovary. The ovary volume was significantly decreased (by 44.4%; P < 0.05) in the group of female pups from Dx‐treated mothers comparing to the controls. The numbers of healthy primordial and atretic follicles were 38.8% (P < 0.05) and 50.9% (P < 0.05), respectively, reduced in the ovaries of pups from the Dx‐treated mothers, when compared with the control values. There were 53.4% (P < 0.05) fewer healthy primary and 41.8% (P < 0.05) fewer healthy secondary follicles as well. The numbers of atretic primary and secondary follicles were reduced by 60.0% (P < 0.05) and 61.7% (P < 0.05), respectively. It can be concluded that fetal exposure to glucocorticoids decreased the pool of non‐growing follicles in the neonatal ovary, whereas the processes of folliculogenesis and atresia remained unaffected.     

Effect of laser preparation on adhesion of a self‐adhesive flowable composite resin to primary teeth

The aim of the study was to evaluate the adhesion of a self‐adhering flowable composite resin to primary tooth enamel and dentin after silicon carbide paper (SiC) and laser pretreatment. Adhesive properties were evaluated as shear bond strength (SBS) and scanning electron microscopic (SEM) characteristics. A total 120 primary canine teeth were randomly divided into two groups to study enamel and dentin. Each group was divided into 6 subgroups (n = 10) according to type of surface preparation (SiC or Er:YAG laser) of enamel or dentin. Three methods were used to build cylinders of restoration on tooth surface: OptiBond All‐In‐One + Premise Flowable composite, OptiBond All‐In‐One + Vertise Flow and Vertise flow. After restoration, samples were tested for SBS and failure mode. Twenty eight samples were examined by SEM. The results of the study showed SBS of Vertise Flow was lower than others in enamel and dentin samples pretreated with SiC and in dentin samples pretreated with laser (P < 0.001). Compared to SiC pretreatment, laser pretreatment led to a significantly higher SBS with Vertise Flow on enamel (P < 0.001). Vertise Flow associated with the adhesive led to a higher SBS in enamel and dentin compared to Vertise Flow alone. Adhesive and mixed failure modes were observed more frequently in Vertise Flow groups. SEM images showed that Vertise Flow led to more irregularities on enamel and more open dentinal tubules after laser ablation compared SiC pretreatment. Microsc. Res. Tech. 79:334–341, 2016. © 2016 Wiley Periodicals, Inc.     

Shear bond strength and ultrastructural interface analysis of different adhesive systems to bleached dentin

Background: It remains unclear as to whether or not dental bleaching affects the bond strength of dentin/resin restoration. Purpose: To evaluated the bond strength of adhesive systems to dentin submitted to bleaching with 38% hydrogen peroxide (HP) activated by LED‐laser and to assess the adhesive/dentin interfaces by means of SEM. Study design: Sixty fragments of dentin (25 mm²) were included and divided into two groups: bleached and unbleached. HP was applied for 20 s and photoactivated for 45 s. Groups were subdivided according to the adhesive systems (n = 10): (1) two‐steps conventional system (Adper Single Bond), (2) two‐steps self‐etching system (Clearfil standard error (SE) Bond), and (3) one‐step self‐etching system (Prompt L‐Pop). The specimens received the Z250 resin and, after 24 h, were submitted to the bond strength test. Additional 30 dentin fragments (n = 5) received the same surface treatments and were prepared for SEM. Data were analyzed by ANOVA and Tukey's test (α = 0.05). Results: There was significant strength reduction in bleached group when compared to unbleached group (P < 0.05). Higher bond strength was observed for Prompt. Single Bond and Clearfil presented the smallest values when used in bleached dentin. SEM analysis of the unbleached specimens revealed long tags and uniform hybrid layer for all adhesives. In bleached dentin, Single Bond provided open tubules and with few tags, Clearfil determined the absence of tags and hybrid layer, and Prompt promoted a regular hybrid layer with some tags. Conclusions: Prompt promoted higher shear bond strength, regardless of the bleaching treatment and allowed the formation of a regular and fine hybrid layer with less deep tags, when compared to Single Bond and Clearfil. Microsc. Res. Tech., 2010. © 2010 Wiley‐Liss, Inc.