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.     

A novel whole tooth-in-jaw-bone culture of rat molars: Morphological, immunohistochemical, and laser capture microdissection analysis

In conventional whole‐tooth culture systems, limitation exists regarding maintenance of the vitality of the dental pulp, because this tissue is encased in rigid dentin walls that hinder nutrition supply. We here report a whole tooth‐in‐jaw‐bone culture system of rat mandibular first molars, where transcardiac perfusion with culture medium was carried out before placement of the jaw bone into culture medium, aiming to facilitate longer time preservation of the dental pulp tissue. Following 7 days of culture, the pulp tissues were analyzed by histology and immunohistochemistry to ED2 (antiresident macrophage). ED2‐positive macrophages were also analyzed for their Class II MHC, interleukin‐6 (IL‐6), and p53 mRNA expression levels by means of immune‐laser capture microdissection (immune‐LCM). Dentin sialophosphoprotein (DSPP) mRNA expression in odontobalstic layer was also examined by LCM. Teeth cultured following saline‐perfusion and nonperfusion served as cultured controls. Normal teeth also served as noncultured controls. Histological examination demonstrated that the structure of the pulp tissue was well preserved in the medium‐perfused explants in contrast to the cultured control groups. The Class II MHC, IL‐6, and p53 mRNA expression levels of ED2‐positive cells and DSPP expression levels of odontoblastic layer tissues in the pulp of medium‐perfused explants were not significantly different from those in the noncultured normal teeth. In conclusion, the structural integrity and mRNA expression in the pulp were maintained at the in vivo level in the ex vivo whole tooth‐in‐jaw‐bone culture system. The system may lay the foundation for studies aiming at defining further histological and molecular mechanism of the pulp. Microsc. Res. Tech. 2012. © 2012 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.     

Erosion effects on chemical composition and morphology of dental materials and root dentin

Purpose: This work aims to study the erosion on restorative materials and on surrounding dentin. Fifty root dentin samples were obtained from bovine incisors. Methods: Twenty samples were not restored and thirty received cavity preparations. Samples were assigned to five groups: G1, G2: sound dentin (D); G3: composite resin (CR); G4: resin‐modified glass‐ionomer cement (RMGIC); G5: glass‐ionomer cement (GIC). The samples of groups 2–5 were submitted to six cycles (demineralization–remineralization). Samples were analyzed by micro energy‐dispersive X‐ray fluorescence spectrometry (μ‐EDXRF) and by scanning electron microscopy (SEM). Results: Mineral loss was greater in G2 samples than in RMGI > CR > GIC > D (control). SEM images showed pronounced dentin demineralization in groups 2 and 4. The acid erosion has a significant effect on mineral loss (Ca and P) of root dentin without restoration. Conclusions: Composite resin had the best chemical resistance to erosion among all the materials. Fluoride contained in GIC seemed to cause some protection, however, with material degradation. Chemical interaction of tooth‐colored dental materials with root dentin could be assessed by μ‐EDXRF. Microsc. Res. Tech. 75:703–710, 2012. © 2011 Wiley Periodicals, Inc.     

FT‐Raman spectroscopy, µ‐EDXRF spectrometry,and microhardness analysis of the dentin of primary and permanent teeth

The chemical compositions (organic and inorganic contents) and mechanical behaviors of the dentin of permanent and deciduous teeth were analyzed and compared using X‐ray fluorescence spectrometry (µ‐EDXRF) Fourier transform Raman spectroscopy (FT‐Raman) and a microhardness test (HD). Healthy fresh human primary and permanent molars (n = 10) were selected, The buccal surfaces facing upwards were stabilized in an acrylic plate, flattened, polished, and submitted to the µ‐EDXRF, FT‐Raman, and HD analysis. The results of the analysis were subjected to ANOVAs and Mann‐Whitney U/Student's t multiple comparisons tests. The data showed similar values for the dentin of the primary and permanent teeth in P content, organic content (amide I peak), inorganic content ( – 430 and 590), and microhardness, Nevertheless, Ca content and Ca/P weight ratio were higher, and the peak was lower in the dentin of the permanent teeth compared to primary teeth. It be concluded that despite permanent teeth showed more Ca element, both substrates showed similar behavior of chemical and physical properties.     

The effect of final irrigation with MTAD,QMix, and EDTA on smear layer removal and mineral content of root canal dentin

To compare the smear layer removal ability and mineral content of root canal dentine after initial irrigation with NaOCl and final irrigation with MTAD, QMix, and 17% EDTA. Forty extracted human maxillary incisors before root canal preparation and irrigation with NaOCl were randomly divided into four groups (n = 10) according to the type of final irrigants used: MTAD, QMix, 17% EDTA, and control (sterile distilled water). Scanning electron microscopy (SEM) was used to assess the presence of smear layer. SEM energy‐dispersive X‐ray spectroscopy was used to quantify dentin mineral composition in MTAD, QMix, 17% EDTA group, and in no‐treatment samples (no‐treatment group; n = 10). Among the various chelating agents, there were no significant differences in the smear layer removal in the middle and coronal thirds (p > .05). In the apical third, QMix removed significantly more smear layer than 17% EDTA (p < .05), but similarly to MTAD (p > .05). Final irrigation with MTAD resulted in a significant increase in the carbon (C) value compared to EDTA (p < .001). There was no significant difference in the mineral composition between the MTAD and the QMix group, although the values of the mineral elements were significantly altered in the MTAD group. QMix had smear layer removal capability similar to MTAD but better than EDTA in the apical third. MTAD yielded the most pronounced effect on mineral component of root dentin; however, differences were significant only for C level compared to 17% EDTA.     

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.     

Resin luting materials: Tissue response in dog's teeth

The aim of this study was to evaluate radiographically and histologically the pulpal and periapical response to self‐adhesive (Rely X? Unicem) and self‐etching and self‐curing (Multilink^®) resin‐based luting materials in deep cavities in dogs' teeth. Deep class V cavities (0.5‐mm–thick dentin) were prepared in 60 canine premolars and the following materials were applied on cavity floor: Groups I/V—RelyX? Unicem; Groups II/VI—Multilink^®; Groups III/VII—zinc phosphate cement (control) and; Groups IV/VIII—gutta‐percha (control). Cavities were restored with silver amalgam. Animals were euthanized after 10 days (groups I–IV) and 90 days (groups V–VIII). Tooth/bone blocks were radiographed and processed for histopathological evaluation of pulp and periapical tissue response to the materials. All materials presented similar histopathological features and radiographic findings at both periods. The pulp tissue was intact. The apical and periapical regions and periodontal ligament thickness were normal. No inflammatory cells, resorption of mineralized tissue (dentin, cementum, and alveolar bone) or bacteria were observed. The lamina dura was intact and no areas of periapical bone rarefaction or internal/external root resorption were observed radiographically. It can be concluded that Rely X? Unicem and Multilink^® caused no adverse tissue reactions and may be indicated for cementation of indirect restorations in deep dentin cavities without pulp exposure. Microsc. Res. Tech. 78:1098–1103, 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.     

Micro‐ and nanoscale structures of mesiodens dentin: Combined study of FTIR and SAXS/WAXS techniques

A mesiodens is the most common type of supernumerary tooth present in conjunction to normal dentition. A mesiodens may commonly occur in the central region of the upper or lower jaw. A mesiodens is different from normal teeth in terms of structure and shape. The aim of this study is to evaluate the micro‐ and nanoscale structural properties of mesiodens dentin by combined small‐ and wide‐angle X‐ray scattering (SAXS/WAXS) and Fourier transform infrared (FTIR) spectroscopy. Five freshly extracted, noncarious mesiodens and five normal dentin disks prepared from human incisor teeth were compared. Using FTIR, the phosphate‐to‐amide I, carbonate‐to‐phosphate, and carbonate‐to‐amide I band area ratios and the crystallinity index were quantified. SAXS/WAXS were used to study the nanostructure of mesiodens. An increase in the mineral content in the mesiodens dentin with respect to the normal group was found. Crystallinity was also significantly increased and the protein content decreased in the mesiodens dentin compared with that of normal dentin. SAXS/WAXS results revealed that mesiodens dentin has a more calcified tissue. Further, SAXS analysis revealed a nonuniform distribution of dentin fibrils in mesiodens. Microsc. Res. Tech., 78:52–58, 2015. © 2014 Wiley Periodicals, Inc.     

Evaluation of bone strength: correlation between measurements of bone mineral density and drilling force

Bone drilling is a major part of modern orthopaedic surgery which involves the internal fixation of fractured bones. The investigation of bone drilling described in this paper demonstrates the contribution of automation technology towards the study of bone strength. The aim of this preliminary investigation is to establish a relationship between bone drilling forces and measurements of bone mineral density (BMD) by dual energy X-ray absorptiometry (DXA). A linear relationship with a high coefficient of correlation has been found between average drilling forces and BMD measurements at both the greater trochanter and the femoral head of porcine femurs when drilling in the anterior-posterior (AP) direction (i.e. the direction of the DXA scan). It has also been found that in the normal drilling direction (i.e. in the cervical axis direction), which is orthogonal to the DXA scanning direction, there are similar trends between the drilling forces and BMD levels in regions where bone density is more consistent (e.g. the femoral head). The findings of this investigation indicate that analysis of bone drilling forces has the potential to provide useful information about the strength of bone.     

Influence of the microenvironment on gene and protein expression of odontogenic-like and osteogenic-like cells

Progenitor cells play an important biological role in tooth and bone formation, and previous analyses during bone and dentine induction have indicated that they may be a good alternative for tissue engineering. Thus, to clarify the influence of the microenvironment on protein and gene expression, MDPC23 cells (mouse dental papilla cell line) and KUSA/A1 cells (bone marrow stromal cell line) were used, both in vitro cell culture and in intra-abdominal diffusion chambers implanted in 4-week-old male immunodefficient mice (SCID mice). Our results indicate that KUSA/A1 cells differentiated into osteoblast-like cells and induced bone tissue inside the chamber, whereas, MDPC-23 showed odontoblast-like characteristics but with a low ability to induce dentin formation. This study shows that MDPC-23 cells are especial cells, which possess morphological and functional characteristics of odontoblast-like cells expressing dentin sialophosphoprotein in vivo. In contrast, dentin sialophosphoprotein gene and protein expression was not detected in both cell lines in vitro. The intra-abdominal diffusion chamber appears as an interesting experimental model for studying phenotypic expression of dental pulp cells in vivo.     

Effect of black tea and matrix metalloproteinase inhibitors on eroded dentin in situ

Purpose of this in situ study was to evaluate the surface properties of eroded dentin specimens activated with three different matrix metalloproteinase (MMP) inhibitors (chlorhexidine [CHX], fluoride, green tea), black tea, and water. One hundred eighty dentin samples were prepared from extracted third molars and then samples divided into six groups. Ten volunteers were carried three specimens of each group, on acrylic palatal appliances, which were fabricated exactly for them (n = 3). Erosive cycles were done by immersing appliances in cup containing Cola and was followed by rinsing with test solutions. Microhardness values were measured. Surface properties were investigated by atomic force microscopy (AFM). Lowest change in microhardness was shown in fluoride group whereas negative control group (water) had the highest change. There were no statistically significant differences among surface roughness changes (p > .05). The least change in microhardness was seen in the fluoride group (13.05 ± 8.07), while the control group showed the highest change (33.80 ± 12.42) and was statistically significant when compared to other groups (p < .05). Besides lowest depth, values were shown in fluoride group as well. AFM evaluations showed macromolecular deposits on surfaces of fluoride, CHX, and black tea groups. No superior results were detected in CHX + fluoride group and black tea showed similar surface characteristics as green tea. Mouthrinses containing not only green tea but also black tea could be beneficial for patients with exposed dentin surfaces. Catechines and theaflavins in teas could be useful for improving surface quality.     

Technical advances in the sectioning of dental tissue and of on‐section cross‐linked collagen detection in mineralized teeth

Immunohistochemical detection of cross‐linked fibrillar collagens in mineralized tissues is much desired for exploring the mechanisms of biomineralization in health and disease. Mineralized teeth are impossible to section when embedded in conventional media, thus limiting on‐section characterization of matrix proteins by immunohistochemistry. We hypothesized that by using an especially formulated acrylic resin suitable for mineralized dental tissues, not only sectioning of teeth would be possible, but also our recently developed immunofluorescence labeling technique would be amenable to fully calcified tissues for characterization of dentinal fibrillar collagens, which remains elusive. The hypothesis was tested on fixed rodent teeth embedded in Technovit 9100 New®. It was possible to cut thin (1 μm) sections of mineralized teeth, and immunofluorescence characterization of cross‐linked type I fibrillar collagen was selected due to its abundance in dentine. Decalcified samples of teeth embedded in paraffin wax were also used to compare immunolabeling from either method using the same immunoreagents in equivalent concentrations. In the decalcified tissue sections, type I collagen labeling in the dentine along the tubules was “patchy” and the signal in the predentine was very weak. However, enhanced signal in mineralized samples with type I collagen was detected not only in the predentine but also at the limit between intertubular dentine, within the elements of the enamel organ and subgingival stroma. This report offers advances in sectioning mineralized dental tissues and allows the application of immunofluorescence not only for on‐section protein detection but importantly for detecting cross‐linked fibrous collagens in both soft and mineralized tissue sections. Microsc. Res. Tech. 73:741–745, 2010. © 2009 Wiley‐Liss, Inc.     

Micro‐shear bond strength of adhesives with different degrees of acidity: Effect on sound and artificially hypermineralized dentin

This study evaluates the bond strength of four self‐etching adhesive systems with different acidity levels in normal and artificially hypermineralized dentin substrate. Healthy human molars were divided into groups: normal dentin—N (n = 36) and artificially hypermineralized dentin—H (n = 36). Self‐etching adhesive systems Clearfil S³ Bond (n = 9), Optibond All in One (n = 9), Clearfil SE Bond (n = 9), and Adhese (n = 9) were used for both the N and H groups. Transparent cylindrical matrices were positioned on the treated dentin surfaces, filled with composite resin, and light‐cured for 40 s. After the transparent cylindrical matrices were removed, the specimens were stored for 24 hr in a humid environment at 37°C and were subjected to a micro‐shear bond strength test. For each group, a specimen was prepared and evaluated in scanning electron microscope for adhesive interface observation. Normality was confirmed and the two‐way analysis of variance and Games–Howell post‐tests were conducted (α = .05). The data demonstrated an interaction between the adhesive system and type of dentin substrate (p < .01). For normal dentin, all adhesive systems assessed were adequate; however, in the hypermineralized dentin, the Clearfil SE Bond two‐step self‐etching adhesive system with mild pH presented the highest immediate bond strength. There was a predominance of adhesive failures for all adhesive systems in the different dentin substrates evaluated. It was concluded that the self‐etching adhesive systems evaluated were efficient for both substrates, and for the hypermineralized dentin, the Clearfil SE Bond presented a higher bond strength value.     

Comparison of methods for quantifying dental wear caused by erosion and abrasion

Various methods have been applied to evaluate the effect of erosion and abrasion. So, the aim of this study was to check the applicability of stylus profilometry (SP), surface hardness (SH) and focus‐variation 3D microscopy (FVM) to the analysis of human enamel and dentin subjected to erosion/abrasion. The samples were randomly allocated into four groups (n = 10): G1‐enamel/erosion, G2‐enamel/erosion plus abrasion, G3‐dentin/erosion, and G4‐dentin/erosion plus abrasion. The specimens were selected by their surface hardness, and they were subjected to cycles of demineralization (Coca‐Cola®‐60 s) and remineralization (artificial saliva‐60 min). For groups G2 and G4, the remineralization procedures were followed by toothbrushing (150 strokes). The above cycle was repeated 3×/day during 5 days. The samples were assessed using SH, SP, and FVM. For each substrate, the groups were compared using an unpaired t‐test, and Pearson correlation coefficients were calculated (α = 5%). For enamel, both profilometry technique showed greater surface loss when the erosion and abrasion processes were combined (P <0.05). The correlation analysis did not reveal any relationships among SH, SP, and FVM to G2 and G4. There were significant correlation coefficients (–0.70 and –0.67) for the comparisons between the FVM and SH methods in enamel and dentin, respectively, in G1 and G3. Choosing the ideal technique for the analysis of erosion depends on the type of dental substrate. SP was not sufficiently sensitive to measure the effects on dentin of erosion or erosion/abrasion. However, SP, FVM and SH were adequate for the detection of tissue loss and demineralization in enamel. Microsc. Res. Tech., 2013. © 2012 Wiley Periodicals, Inc.     

Effects of sodium hypochlorite as dentin deproteinizing agent and aging media on bond strength of two conventional adhesives

This study evaluated the effect of 10% sodium hypochlorite (NaOCl) as deproteinizing agent and storage media on bond strength (BS) of two etch‐and‐rinse adhesive systems to dentin. Twenty‐eight sound extracted human third molars were divided in four groups (n = 7), according to dentin treatment (conventional etching or etching followed by 10% NaOCl application) and adhesive systems (GB—Gluma 2Bond and OS—One‐Step). After dentin treatments and adhesive application, a composite block was built‐up on dentin surface and teeth were serially sectioned to obtain bonded sticks specimens. The sticks were submitted to three aging conditions: (24H) 24 hr in water (immediate), (SH) 3 hr of NaOCl accelerated‐aging or (1Y) 1 year of water storage. Afterward, submitted to microtensile bond strength test (μTBS), failure modes and adhesive interfaces analyzes. Data were analyzed by two‐way analysis of variance (ANOVA) and Tukey's test (α = .05). Dentin deproteinization before bonding significantly reduced μTBS for GB‐treated group (p < .05), regardless the aging conditions. Water storage for 1 year (1Y) and NaOCl accelerated‐aging (SH) decreased μTBS for both adhesives. Yet, the groups stored in NaOCl (SH) exhibited the lowest BS results (p < .05). Bond strength of deproteinized dentin was dependent on the adhesive system composition and NaOCl accelerated‐aging promoted decreased bond strength and further degradation than water storage for 1 year.     

Advantages of a combined method of decalcification compared to EDTA

Decalcification of mineralized tissues is an essential step during tissue processing in the routine histopathology. The time required for complete decalcification, and the effect of decalcifier on cellular and tissue morphology are important parameters which influence the selection of decalcifying agents. In this study, we compared a decalcifying solution (ETDA) composed of both acid and chelating agents to a classical and well‐known decalcifying agent (EDTA). To this purpose, the optic density of bone radiographs, residual calcium analysis, bone sample weight, and histological and immunohistochemical analysis were performed. Our data suggest that, similarly to EDTA, the ETDA solution completely removes the calcium ions from the samples enabling easy sectioning. However, unlike the EDTA, this agent takes much less time. Furthermore, both agents showed comparable decalcification efficacy, and similarly, they did not produce cellular, tissue or antigenicity impairments. Therefore, ETDA may be a suitable option when it is necessary an association between a rapid and complete removal of calcium minerals, and a suitable preservation of structure and antigenicity of tissues. Microsc. Res. Tech. 78:111–118, 2015. © 2014 Wiley Periodicals, Inc.     

Scanning and transmission electron microscopy for evaluation of order/disorder in bone structure

A comparative characterization of the structure of normal and abnormal (osteoporotic) human lumbar and thoracic vertebrae samples was carried out to reveal the type of possible disorder. Samples from the bone fragments extracted during the surgery due to vertebra fractures were examined by scanning electron microscopy (SEM), conventional and high resolution transmission electron microscopy (TEM and HRTEM), and X-ray energy dispersive spectroscopy (EDS). Contrary to what might be expected in accordance with possible processes of dissolution, formation and remineralization of hard tissues, no changes in phase composition of mineral part, crystal sizes (length, width, and thickness), and arrangement of crystals on collagen fibers were detected in abnormal bones compared to the normal ones. The following sizes were determined by HRTEM for all bone samples: 相似文献