Penetration of resin‐based materials into initial erosion lesion: A confocal microscopic study

The application of resin‐based materials is an alternative of treatment for eroded lesions. Nevertheless, there are no studies about the penetration of these materials into eroded lesion, which might affect its adhesion. Therefore, this study evaluated the penetration of four resin‐based materials, with and without enamel etching. By using an in vitro protocol, types of treatment were studied at five levels (AdheSE^®, Tetric N‐Bond^®, Single Bond 2^®, Helioseal Clear^®, Icon^®) and types of enamel etching in two levels (with and without). Materials were stained with 0.02 mg/mL ethanolic solution of tetramethylrhodamine isothiocyanate. Bovine enamel samples (4 × 4 mm) were immersed in 0.01 M HCl, pH 2.3, for 30 seconds to produce initial eroded lesions. Afterward, the materials were applied on half of sample enamel surface following the manufacturer's instructions. On the other half of sample, the materials were applied without etching the enamel. Materials penetration into the enamel was assessed by Confocal Laser Scanning Microscopy on reflection and fluorescence modes. The penetration depth (PD) was measured using ImageJ software. Data were analyzed by two‐way ANOVA and Tukey test (P < 0.05). Regardless of the material, etched enamel resulted in higher PD than non‐etched (P < 0.05). Icon^® showed the highest PD in enamel followed by Helioseal Clear^® (P < 0.05), with significant difference between them (P < 0.05) and no difference was found among AdheSE^®, Tetric N‐Bond^®, and Single Bond 2^® (P > 0.05). It can be concluded that prior enamel etching increased the materials penetration into eroded enamel and the Icon^®—infiltrant presented highest penetration. Microsc. Res. Tech. 79:72–80, 2016. © 2015 Wiley Periodicals, Inc.     

Chemical and crystallographic study of remineralized surface on initial carious enamel treated with Galla chinensis

To investigate the morphologic, chemical and crystallographic characters of remineralized surface on initial carious enamel treated with Galla chinensis, scanning electron microscopy equipped with energy dispersive analysis spectroscopy were used, and X‐ray microdiffraction (microzone XRD) was used for the first time to analyze in situ the microzone crystallite of remineralized surface on carious enamel. Bovine sound enamel slabs were demineralized to produce initial carious lesion in vitro. Then, the lesions were exposed to a pH‐cycling regime for 12 days of remineralization. Each daily cycle included 4×1 min applications with one of the three treatments: distilled and deionized water (DDW); 1 g/L NaF; 4 g/L G. chinensis extract (GCE). After the treatments, some rod‐like deposits and many irregular prominences were found on GCE‐treated enamel surface, and the intensities of Ca and P signals showed a tendency to increase; Ca:P ratio was significantly higher than that of DDW‐treated enamel. X‐ray microdiffraction showed hydroxyapatite was still the main component of GCE‐treated enamel, and the crystallinity was increased, the crystal lattice changed gently with decreased lattice parameter a. These results indicated the potential of GCE in promoting the remineralization of initial enamel carious lesions, and supported the previous hypothesis about GCE mechanism. Combined with the anti‐bacteria and demineralization inhibition properties of GCE, the natural G. chinensis may become one more promising agent for caries prevention. SCANNING 31: 236–245, 2009. © 2010 Wiley Periodicals, Inc.     

Zinc oxide 3D microstructures as an antimicrobial filler content for composite resins

The aim of this study was to evaluate the antibacterial activity of a composite resin modified by 3D zinc oxide (ZnO) microstructures and to verify possible alterations on its mechanical properties. ZnO was synthesized by hydrothermal approach and characterized by X‐ray diffraction (XRD), surface area by Brunauer, Emmett and Teller (BET), Fourier transform infrared spectroscopy (FTIR) and Field emission scanning electron microscopy (FESEM). The minimum inhibitory concentrations of ZnO against Streptococcus mutans, Escherichia coli, Staphylococcus aureus, and Candida albicans were determinated. The composite resin Filtek^TM Z350XT (3M of Brazil) was blended with 0.2%, 0.5%, and 1% in weight of ZnO and submitted to antibacterial assay by direct contact test against S. mutans, the leading cause of dental caries and the most cariogenic oral streptococci. Additionally, it was performed compressive and diametral tensile strength tests of the modified composite resin. Microrods and hollow microrods of ZnO were obtained and its MIC values were found to be 125 μg/mL for S. mutans, 500 μg/mL for C. albicans and 62.5 μg/mL for S. aureus. For the tested concentrations, it was not found MIC against E. coli. The direct contact test showed a significant antibacterial capacity of modified composite resin (p > 0.05 for all concentrations). The compressive and diametral tensile strength remains no changed after inclusion of microparticles (p > 0.05 for all concentrations). The modification of the composite resin with small amounts of ZnO microparticles significantly inhibited the S. mutans growth on resin surface without significant alterations of its mechanical strength.     

Microhardness and SEM after CO2 laser irradiation or fluoride treatment in human and bovine enamel

Background: It remains uncertain as to whether or not CO₂ laser is able to hinder demineralization of enamel. The possibility to use bovine instead of human teeth on anticariogenic studies with laser has not yet been determined. Purpose: To compare the ability of CO₂ laser and fluoride to inhibit caries‐like lesions in human enamel and to test whether a similar pattern of response would hold for bovine enamel. Study Design: Ninety‐six enamel slabs (2 × 2 × 4 mm) (48 from bovine and 48 from human teeth) were randomly distributed according to surface treatment (n = 12): CO₂ laser, 5% sodium fluoride varnish (FV), 1.23% acidulated phosphate fluoride (APF) gel, or no treatment (control). Specimens were subjected to a 14‐day in vitro cariogenic challenge. Microhardness (SMH) was measured at 30 μm from the surface. For ultrastructural analysis, additional 20 slabs of each substrate (n = 5) received the same treatment described earlier and were analyzed by SEM. Results: ANOVA and Tukey test ascertained that CO₂ laser promoted the least mineral loss (SMH = 252^a). Treatment with FV resulted in the second highest values (207^b), which was followed by APF (172^c). Untreated specimens performed the worst (154^d). SEM showed no qualitative difference between human and bovine teeth. APF and control groups exhibited surfaces covered by the smear layer. A granulate precipitate were verified on FV group and fusion of enamel crystals were observed on lased‐specimens. Conclusions: CO₂ laser may control caries progression more efficiently than fluoride sources and bovine teeth may be a suitable substitute for human teeth in studies of this nature. Microsc. Res. Tech. 73:1030–1035, 2010. © 2010 Wiley‐Liss, Inc.     

Analysis of efficacy of the self‐assembling peptide‐based remineralization agent on artificial enamel lesions

The objective of this in vitro study was to analyze and compare the biomimetic remineralizing efficacy of the self‐assembling peptide (P11‐4) with agents containing casein phoshopeptide‐amorhous calcium phosphate fluoride (CPP‐ACFP) and sodium fluoride (NaF) on artificial caries lesions using DIAGNOdent and micro‐computed tomography (μCT). Artificial enamel lesions were prepared on extracted impacted sound mandibular third molars. The samples were randomly allocated to four groups (n = 8): Group 1, P11‐4 (Curodont Repair, Credentis AG, Switzerland); Group 2, CPP‐ACFP (MI Varnish, GCCo., Japan); Group3, NaF (Duraphat Varnish, Colgate, Colgate‐Palmolive, NY, USA); Group 4, artificial saliva (control). The agents were applied to demineralized surfaces according to manufacturers' instructions; all specimens were stored in artificial saliva for 1 month. Demineralization and remineralization on enamel surfaces were analyzed and quantified by DIAGNOdent (KaVo, Germany) and μCT (SkyScan1174, Belgium) for lesion depth/area/volume/mineral density (MD). The remineralization efficacy of the agents was evaluated by DIAGNOdent on 1st, 7th, 30th days and by μCT on 30th day. Data were statistically analyzed by ANOVA, Kruskal–Wallis, T test, and Wilxocon tests. The highest remineralization efficacy findings in all periods were determined in Group 1, followed by Groups 2, 3, and 4. The remineralization findings for fluorescence, MD, lesion depth in Group 1 were found significantly higher (p < 0.01) than Group 3; and no significant differences (p > 0.05) were found between Groups 1–2 and Groups 2–3. The area and volume change values in Groups 1, 2, and 3 have shown no significancy (p > 0.05). A significant correlation (p < 0.01) was found between μCT and DIAGNOdent methods. The data of this study have demonstrated that P11‐4 has showed the best remineralization efficacy, followed by CPP‐ACFP and NaF. It is concluded that self‐assembling peptide‐based remineralization agent can be used successfully for biomimetic remineralization of enamel subsurface lesions.     

Stress and strain distribution in demineralized enamel: A micro‐CT based finite element study

Physiological oral mechanical forces may play a role on the progression of enamel carious lesions to cavitation. Thus, the aim of this study was to describe, by 3D finite element analysis, stress, and strain patterns in sound and carious enamel after a simulated occlusal load. Micro‐CT based models were created and meshed with tetrahedral elements (based on an extracted third molar), namely: a sound (ST) and a carious tooth (CT). For the CT, enamel material properties were assigned according to the micro‐CT gray values. Below the threshold corresponding to the enamel lesion (2.5 g/cm³) lower and isotropic elastic modulus was assigned (E = 18 GPa against E₁ = 80 GPa, E₂ = E₃ = 20 GPa for sound enamel). Both models were imported into a FE solver where boundary conditions were assigned and a pressure load (500 MPa) was applied at the occlusal surface. A linear static analysis was performed, considering anisotropy in sound enamel. ST showed a more efficient transfer of maximum principal stress from enamel to the dentin layer, while for the CT, enamel layer was subjected to higher and concentrated loads. Maximum principal strain distributions were seen at the carious enamel surface, especially at the central fossa, correlating to the enamel cavity seen at the original micro‐CT model. It is possible to conclude that demineralized enamel compromises appropriate stress transfer from enamel to dentin, contributing to the odds of fracture and cavitation. Enamel fracture over a dentin lesion may happen as one of the normal pathways to caries progression and may act as a confounding factor during clinical diagnostic decisions. Microsc. Res. Tech. 78:865–872, 2015. © 2015 Wiley Periodicals, Inc.     

Effects of Galla chinensis on the surface topography of initial enamel carious lesion: an atomic force microscopy study

To investigate the effect of Galla chinensis on the surface topography of initial enamel carious lesion, atomic force microscope (AFM) was used, and it was a new AFM application in enamel de‐/remineralization research. Bovine sound enamel slabs were demineralized to produce initial carious lesion in vitro. Then, the lesions were exposed to a pH‐cycling regime for 12 days. Each daily cycle included 4×1 min applications with one of three treatments: negative control group: deionized water; positive control group: 1 g/L aqueous solutions of NaF; experimental group: 4 g/L aqueous solutions of G. chinensis extract (GCE). The surface topography and roughness were investigated on the enamel slabs before and after pH‐cycling by AFM. 3D AFM images revealed the surface topographical changes of GCE‐treated enamel. Significant difference existed before and after the pH‐cycling among the groups. AFM offers a powerful tool for enamel de‐/remineralization research. The surface roughness results provide the evidences to remineralization of carious lesion, and indicate the potential of G. chinensis in promoting the remineralization. G. chinensis may become one more promising agent for caries prevention. SCANNING 31: 195–203, 2009. © 2010 Wiley Periodicals, Inc.     

Enamel erosion and prevention efficacy characterized by confocal laser scanning microscope

The aim of this study was to evaluate the erosion‐inhibiting effect of two toothpastes on the development of erosion‐like lesions, by a confocal laser scanning microscope (CLSM). Forty human enamel blocks were divided into five groups (n = 8), in accordance to evaluate the GC MI Paste Plus and Oral B with stannous fluoride, applied as slurries and associated with toothbrush. Specimens were submitted to an erosion challenge from citric acid (0.5%, pH = 2.8), for 5 min, six times a day, alternating in artificial saliva immersions. Reference group was not exposed to treatment. Part of specimens (Groups 02 and 03) was exposed twice daily just to slurries, for 2 min, therefore specimens from Groups 04 and 05 were also abraded, for 30 s. The enamel surfaces were morphological characterized using CLSM images, with mineral loss being measured using the resulting 3D images referenced to an un‐challenged portion of the sample. Step values were compared using the one‐way ANOVA test. CLSM was shown to be a viable, noncontact, and simple technique to characterize eroded surfaces. The statistical difference in the step size was significant between the groups (P = 0.001) and using multiple comparisons a statistically significant protective effect of toothpastes was shown when these were applied as slurries. Although groups submitted to tooth brush showed mineral loss similar to reference control group, due to the damages of abrasion associated. Microsc. Res. Tech. 77:439–445, 2014. © 2014 Wiley Periodicals, Inc.     

Effect of Er:YAG laser irradiation on deciduous enamel roughness and bacterial adhesion: An in vitro study

Laser irradiation has been proposed as a preventive method against dental caries since it is capable to inhibit enamel demineralization by reducing carbonate and modifying organic matter, yet it can produce significant morphological changes. The purpose of this study was to evaluate the influence of Er:YAG laser irradiation on superficial roughness of deciduous dental enamel and bacterial adhesion. Fifty‐four samples of deciduous enamel were divided into three groups (n = 18 each). G1_control (nonirradiated); G2_100 (7.5 J/cm²) and G3_100 (12.7 J/cm²) were irradiated with Er:YAG laser at 7.5 and 12.7 J/cm², respectively, under water irrigation. Surface roughness was measured before and after irradiation using a profilometer. Afterwards, six samples per group were used to measure bacterial growth by XTT cell viability assay. Adhered bacteria were observed using confocal laser scanning microscopy (CLSM) and a scanning electron microscopy (SEM). Paired t‐, one‐way analysis of variance (ANOVA), Kruskal‐Wallis and pairwise Mann–Whitney U tests were performed to analyze statistical differences (p < .05). Before treatment, samples showed homogenous surface roughness, and after Er:YAG laser irradiation, the surfaces showed a significant increase in roughness values (p < .05). G3_100 (12.7 J/cm²) showed the highest amount of Streptococcus mutans adhered (p < .05). The increase in the roughness of the tooth enamel surfaces was proportional to the energy density used; the increase in surface roughness caused by laser irradiation did not augment the adhesion of Streptococcus sanguinis; only the use of the energy density of 12.7 J/cm² favored significantly the adhesion of S. mutans.     

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.     

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.     

Resin-tooth interfacial morphology and sealing ability of one-step self-etch adhesives: microleakage and SEM study

OBJECTIVES: To compare microleakage of three self‐etch adhesives and to analyze enamel surface morphology and interfacial morphology of resin–enamel and resin–dentin interface under scanning electron microscope (SEM). EXPERIMENTAL DESIGN: Study was conducted in 65 extracted human premolars. Class V cavities were prepared in 45 teeth and assigned to three groups (n = 15) according to three self‐etch adhesives (OptiBond All‐in‐One, iBond, and Adper Prompt L‐Pop). After restoration, 10 samples from each group were used to assess microleakage at enamel and dentin margin. Five samples from each group were used for analysis of interfacial morphology at resin–enamel and resin–dentin interface under SEM. Remaining 20 teeth were used to prepare flat enamel buccal surfaces to analyze the difference in surface morphology after treatment with three adhesives (n = 5 each) and 36% phosphoric acid treatment (n = 5). PRINCIPAL OBSERVATIONS: At enamel margin, Prompt L‐Pop depicted least leakage of all the three adhesives and also showed best interfacial adaptation under SEM. At dentin margin, OptiBond All‐in‐One showed significant less leakage than iBond and Prompt L‐Pop. On flat enamel surface, phosphoric acid produced the most retentive etching pattern when compared with the three adhesives. CONCLUSION: Prompt L‐Pop showed the best bonding effectiveness in enamel, whereas OptiBond All‐in‐One performed significantly better in dentin. Microsc. Res. Tech. 2012. © 2012 Wiley Periodicals, Inc.     

Active application of primer acid on acid‐treated enamel: Influence on the bond effectiveness of self‐etch adhesives systems

Aim: Evaluate the composite‐to‐enamel bond after passive or active application of self‐etching primer systems on polished or pre‐etched enamel with phosphoric acid. Materials and Methods: Two self‐etch adhesives systems (SEAS) were used: Clearfil SE Bond and Easy Bond. Third human molars were divided into 8 groups (N = 10). The crown of each tooth was sectioned into halves and the mesial/distal surfaces were used. The adhesives were actively or passively applied on enamel with or without prior phosphoric‐acid etching. Resin composite cylinders were built after adhesive application. After stored in relative humidity for 24 hr/37°C the specimens were subjected to microshear test in universal testing a machine at a crosshead speed of 0.5 mm/minute. The results were analyzed with three‐way ANOVA and the Tukey test. The enamel‐etching pattern was evaluated under SEM. Results: The 2‐step SEAS system presented significantly higher adhesive bond strength means (47.37 MPa) than the 1‐step (36.87 MPa). A poor enamel‐ etching pattern was observed in active mode showing irregular and short resin tags, however there was not compromised the bond strength. Conclusion: Active or passive application produced similar values of bond strength to enamel regardless of enamel pretreatment and type of SEAS.     

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.     

Three‐dimensional Co‐culture of hepatic progenitor cells and mesenchymal stem cells in vitro and in vivo

Introduction: Here we co‐cultured hepatic progenitor cells (HPCs) and mesenchymal stem cells (MSCs) to investigate whether the co‐culture environments could increase hepatocytes form. Methods: Three‐dimensional (3D) co‐culture model of HPCs and MSCs was developed and morphological features of cells were continuously observed. Hepatocyte specific markers Pou5f1/Oct4, AFP, CK‐18 and Alb were analyzed to confirm the differentiation of HPCs. The mRNA expression of CK‐18 and Alb was analyzed by RT‐PCR to investigate the influence of co‐culture model to the terminal differentiation process of mature hepatocytes. The functional properties of hepatocyte‐like cells were detected by continuously monitoring the albumin secretion using Gaussia luciferase assays. Scaffolds with HPCs and MSCs were implanted into nude mouse subcutaneously to set up the in vivo co‐culture model. Results: Although two groups formed smooth spheroids and high expressed of CK‐18 and Alb, hybrid spheroids had more regular structures and higher cell density. CK‐18 and Alb mRNA were at a relatively higher expression level in co‐culture system during the whole cultivation time (P < 0.05). Albumin secretion rates in the hybrid spheroids had been consistently higher than that in the mono‐culture spheroids (P < 0.05). In vivo, the hepatocyte‐like cells were consistent with the morphological features of mature hepatocytes and more well‐differentiated hepatocyte‐like cells were observed in the co‐culture group. Conclusions: HPCs and MSCs co‐culture system is an efficient way to form well‐differentiated hepatocyte‐like cells, hence, may be helpful to the cell therapy of hepatic tissues and alleviate the problem of hepatocytes shortage. Microsc. Res. Tech. 78:688–696, 2015. © 2015 Wiley Periodicals, Inc.     

3D‐quantum interferometer using silicon microring‐embedded gold grating circuit

A 3D (three‐dimensional) quantum interferometer consisting of a silicon microring circuit proposed. The interferometer based on the electron spin cloud projections generated by microring‐embedded gold grating. The electron cloud oscillations result from the excitation of the gold grating at the center of the silicon microring by the dark soliton pulse of 1.50 μm center wavelength. The electron cloud spin‐down, spin‐up automatically formed in the two axes (x, y, respectively) and propagated along the z‐axis. In this proposal, the sensing mechanism of the circuit is manipulated by varying the reflector gold lengths of the sensing arm. The electron cloud spin coupled and changed by changing the gold lengths. The sensitivity measurement of the 3D quantum interferometer for three gold layer lengths of 100 nm, 500 nm, and 1,000 nm is (47.62 nm fs^?1, ±0.4762 fs^?1, ±0.01 nm^?1), (238.10 nm fs^?1, ±0.4762 fs^?1, ±0.002 nm^?1), (476.20 nm fs^?1, ±0.4762 fs^?1, ±0.001 nm^?1), respectively. The used circuit parameters are the real ones that can be fabricated by the currently available technology. Moreover, the silicon micro ring circuit acts as a plasmonic antenna, which can apply for wireless quantum communication. The electron cloud spin projection space–time control can apply for quantum cellular automata.     

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.     

Influence of Er:YAG laser frequency on dentin caries removal capacity

The purposes of this study were to evaluate in vitro the influence of different frequencies of Er:YAG laser on the human dentin caries removal capacity. Thirty fragments obtained from third molars were randomly assigned into three groups (n = 10) according to the laser frequency used: 4, 6, and 10 Hz. The caries lesion (±1 mm deep) was induced before the irradiation by S.mutans cultures for 6 weeks. The specimens of all groups were irradiated with 200 mJ of energy in noncontact and focused mode under constant refrigeration (water flow: 2.5 mL/min). Quantitative analysis of the caries removal was performed by DIAGNOdent^TM and the Axion Vision^TM software. Qualitative analysis was performed by Scanning electron microscope (SEM) and light microscope (LM). Data were analyzed by ANOVA and Fishers' tests. The DIAGNOdent^TM revealed that the caries removal was similar with 4 and 6 Hz and was superior with 10 Hz (P < 0.05). The analysis with Axion Vision^TM software revealed that the caries removal was similar with 6 and 10 Hz and the 4 Hz group promoted the lowest caries removal. Through SEM morphologic analysis, some specimens irradiated with 4 Hz presented, under the demineralized dentin, a disorganized collagenous matrix. The LM images revealed that all frequencies used promoted irregular caries removal, being observed over preparations with 6 and 10 Hz. It can be concluded that the increase of Er:YAG laser frequency provided a higher dentin caries removal without selectivity to the disorganized dentin. Microsc. Res. Tech., 2010. © 2010 Wiley‐Liss, Inc.     

In Situ analysis of CO2 laser irradiation on controlling progression of erosive lesions on dental enamel

The present study aimed to evaluate in situ the effect of CO₂ laser irradiation to control the progression of enamel erosive lesions. Fifty‐six slabs of bovine incisors enamel (5 × 3 × 2.5 mm³) were divided in four distinct areas: (1) sound (reference area), (2) initial erosion, (3) treatment (irradiated or nonirradiated with CO₂ laser), (4) final erosion (after in situ phase). The initial erosive challenge was performed with 1% citric acid (pH = 2.3), for 5 min, 2×/day, for 2 days. The slabs were divided in two groups according to surface treatment: irradiated with CO₂ laser (λ = 10.6 µm; 0.5 W) and nonirradiate. After a 2‐day lead‐in period, 14 volunteers wore an intraoral palatal appliance containing two slabs (irradiated and nonirradiated), in two intraoral phases of 5 days each. Following a cross‐over design during the first intraoral phase, half of the volunteers immersed the appliance in 100 mL of citric acid for 5 min, 3×/day, while other half of the volunteers used deionized water (control). The volunteers were crossed over in the second phase. Enamel wear was determined by an optical 3D profilometer. Three‐way ANOVA for repeated measures revealed that there was no significant interaction between erosive challenge and CO₂ laser irradiation (P = 0.419). Erosive challenge significantly increased enamel wear (P = 0.001), regardless whether or not CO₂ laser irradiation was performed. There was no difference in enamel wear between specimens CO₂‐laser irradiated and non‐irradiated (P = 0.513). Under intraoral conditions, CO₂ laser irradiation did not control the progression of erosive lesions in enamel caused by citric acid. Microsc. Res. Tech. 77:586–593, 2014. © 2014 Wiley Periodicals, Inc.