Does the combination of whitening toothpaste and hydrogen peroxide bleaching increase the surface roughness and change the morphology of a nanofilled composite?

Aim: To evaluate changes in the surface roughness and morphology of a nanofilled composite following toothbrushing with a whitening (WT) or regular toothpaste (RT), alone or combined with 35% hydrogen peroxide bleaching (HP). Methods: Seventy disc-shaped nanofilled composite (Filtek Z350XT) specimens were randomly divided into groups (n=10): WT, RT, TB (without toothpaste ­ control) or the combinations WT/ HP, RT/HP, TB/HP and HP. All groups underwent toothbrushing simulation (60,000 cycles) and bleaching treatment (4 sessions). Mean surface roughness (Ra, µm) was measured before (T0) and after treatments (TB). Surface morphology was assessed by scanning electron microscopy (SEM) at TB. Mean Ra was analyzed using general mixed models and multiple comparisons by the Tukey-Kramer test (α=5%). Results: HP caused no surface roughness changes on the nanofilled composite after treatment (p>0.05). RT toothbrushing, combined or not with HP, increased the surface roughness (p<0.05). WT and WT/ HP protocols had no effect on the surface roughness of the composite (p>0.05). The nanofilled composite submitted to RT toothbrushing combined with HP (RT/HP) presented substantial surface alterations under SEM, showing deep depressions and round-shaped defects. Toothbrushing with RT combined with the bleaching agent increased exposure of the inorganic fillers. Conclusion: WT toothbrushing, regardless of HP combination, or the single HP protocol had no effect on the surface roughness of the nanofilled composite. However, RT combined with HP negatively affected surface roughness and presented the most noticeable surface changes among groups

Cross-sectional evaluation of the saccharin transit time test for primary ciliary dyskinesia: did we discard this tool too soon?

ABSTRACT BACKGROUND: Primary ciliary dyskinesia (PCD) is a rare and heterogeneous disease that is difficult to diagnose and requires complex and expensive diagnostic tools. The saccharin transit time test is a simple and inexpensive tool that may assist in screening patients with PCD. OBJECTIVES: This study aimed to compare changes in the electron microscopy findings with clinical variables and saccharin tests in individuals diagnosed with clinical PCD (cPCD) and a control group. DESIGN AND SETTING: An observational cross-sectional study was conducted in an otorhinolaryngology outpatient clinic from August 2012 to April 2021. METHOD: Patients with cPCD underwent clinical screening questionnaires, nasal endoscopy, the saccharin transit time test, and nasal biopsy for transmission electron microscopy. RESULTS: Thirty-four patients with cPCD were evaluated. The most prevalent clinical comorbidities in the cPCD group were recurrent pneumonia, bronchiectasis, and chronic rhinosinusitis. Electron microscopy confirmed the clinical diagnosis of PCD in 16 of the 34 (47.1%) patients. CONCLUSION: The saccharin test could assist in screening patients with PCD due to its association with clinical alterations related to PCD.

Cleaning of long oval canals with WaveOne Gold system associated with different irrigant agitation protocols

Aim: The aim of the study was to evaluate the cleaning of mandibular incisors with WaveOne Gold® (WO) under different preparation techniques. Methods: A total of 210 human mandibular incisors were selected and divided into seven groups (n = 30), prepared by WO single-files (Small 20/.07 ­ WOS; Primary 25/.07 ­ WOP; Medium 35/.06 ­ WOM; or Large 45/.05 - WOL) and sequential-file techniques (WOS to WOP; WOS to WOM; and WOS to WOL). Further subdivision was made according to irrigation protocol: control group (manual irrigation - CON), E1 Irrisonic® - EIR, and EDDY® - EDD. Debris removal and the smear layer were evaluated by scanning electron microscopy. Data were analyzed by using Spearman's correlation test. The significance level was set at 5%. Results: For debris and smear layer removal, WOS and WOP, EIR differed from CON and EDD (p <0.05). Conclusion: Regardless of the instrumentation used, the agitation of the irrigant solution provided better cleanability. These findings reinforce the need for agitation techniques as adjuvants in cleaning root canal systems in mandibular incisors

Scanning electron microscopy of panitumumab-induced eyelash and hair alterations - Pili canaliculi

Abstract Panitumumab is a monoclonal antibody against the epidermal growth factor receptor used in metastatic colorectal cancer; in addition to tumor cells, it acts on epidermal keratinocytes and on the outer root sheath and presents skin toxicity in up to 90% of cases. A scanning electron microscope was used to examine the eyelashes and hairs of a 65-year-old patient with eyelash trichomegaly, curly hair, and paronychia undergoing treatment with panitumumab. Grooving in the hair shafts were identified, which were more evident in the eyelashes. Similar to oral epidermal growth factor inhibitors (erlotinib and gefitinib), panitumumab can cause acquired pili canaliculi.

Age-related changes in pancreatic histology and ultrastructure in rats / 中华老年医学杂志

Objective:To investigate age-related histological and ultrastructural changes of the pancreas in Sprague-Dawley(SD)rats, and to provide a theoretical basis for the high incidence of pancreatic diseases in the elderly.Methods:Thirty 6-month-old specific pathogen-free male SD rats were fed until 6, 12, 18 and 25 months of age.Five rats of each age group were randomly selected, killed and then sampled to make histological(HE staining)and electron microscopic sections to observe age-related changes in pancreatic histology and ultrastructure.Results:The pancreatic tissue of rats showed increasing fibrosis with age, especially around the duct.Fat infiltration of the pancreatic tissue also increased with age( H=15.88, P=0.001). With the increase of age, the number(density)of pancreatic islets decreased gradually( F=3.55, P=0.039), but the average cross-sectional area of islets increased significantly( F=7.76, P=0.002), and the round and oval islets became irregular.Nuclear pyknosis, mitochondrial dehydration, mitochondrial swelling, and dilatation and loose organization of rough endoplasmic reticula were observed in the cytoplasm of pancreatic acinar cells and islet beat cells in aged rats.With the increase of age, the number of zymogen granules at the apical pole of pancreatic acinar cells of rats decreased( F=9.73, P<0.001), and the average area and total area of granules were significantly decreased( F=6.51, P=0.001; F=22.18, P<0.001); The number of non-senescent mitochondria and senescent mitochondria in the cytoplasm of acinar cells increased significantly( H=8.22, P=0.045; H=32.95, P<0.001); The amount of proinsulin in islet beta cells was significantly decreased( F=16.20, P<0.001). Conclusions:With aging, the rat pancreas exhibits a series of degenerative manifestations(stromal hyperplasia, adipose tissue infiltration, decreased numbers of zymogen granules in acinar cells, increases in the number of senescent mitochondria, reduced islets and reduced proinsulin in islet beta cells), while there are some compensatory phenomena(increasing numbers of islets and non-senescent mitochondria).

Heat-treated NiTi instruments and final irrigation protocols for biomechanical preparation of flattened canals

Abstract This study evaluate shaping ability of heat-treated NiTi-alloy instruments associated with different final irrigation protocols in flattened root canals. Thirty human mandibular incisors with flattened root canals were divided into 5 groups (n = 10): (XP) Original Protocol XP-endo Shaper; (XP-WT) Original Protocol XP-endo Shaper with working time variation; (XP-K) XP-endo Shaper with kinematics variation; (XP-WTK) XP-endo Shaper with kinematics and working time variations; (Hyflex) Hyflex CM. For the variation in working time protocols the same sample of the XP-endo Shaper groups with and without kinematic variation were used. To evaluate final irrigation protocols, groups 1, 3 and 5 were submitted to 3 protocols: (NI) No irrigation (n = 2); (CI) conventional irrigation (n = 4), and (EndoVac) irrigation (n = 4). The samples were scanned by microcomputed tomography and prepared for scanning electron microscopy evaluation. Quantitative data were evaluated using the parametric ANOVA test, with statistical significance level set at 5%, and qualitative data obtained were compared to establish the agreement between examiners through the Kappa test. It was observed that in the analysis of XP-endo Shaper protocols, the additional working time did not cause difference in any of parameters evaluated (p > 0.05) in relation to time recommended by manufacturer. Compared to Hyflex, XP-K showed highest mean volume increase (p < 0.05) and lowest percentage of untouched walls (p < 0.05). In the qualitative evaluation, final irrigation protocol with EndoVac provided the best cleaning results when associated with XP-K and with Hyflex. Thus, supplementary techniques are effective tools to enhance cleaning and to promote higher touch of walls during root canal preparation.

Microbiological and microstructural analysis of indwelling bladder catheters and urinary tract infection prevention / Análisis microbiológico y microestructural de sondas vesicales permanentes y prevención de infecciones del tracto urinario / Análise microbiológica e microestrutural dos cateteres vesicais de demora e prevenção de infecção do trato urinário

ABSTRACT Objective: To analyze the microbiological and microstructural part of indwelling urinary catheters and their association with urinary tract infection prevention. Method: This is a cross-sectional study, from June to December 2020, in which 42 indwelling urinary catheter tips and sterile urine samples were collected for analysis of crystals in optical microscopy and biofilms in scanning electron microscopy. Culture analysis and specification of the type of bacteria were performed. Results: It was found that 35.71% of the samples had mature biofilm adhered to the catheter tip. Biofilms of Proteus mirabilis, Enterococcus faecalis, Staphylococcus epidermidis, Enterococcus faecium and Enterobacter cloacae stood out. The presence of magnesium-ammonium-phosphate crystal was associated with the presence of urinary tract infection and with Proteus mirabilis. There was a significant association (p = 0.001) between the use of prophylactic antibiotics versus urine culture >105 CFU/mL. Conclusion: The analyzes contributed to clinical practice, as it reinforces the development of effective and monitored strategies on cultures and urinary tract infection prevention associated with indwelling urinary catheters.

RESUMEN Objetivo: Analizar la parte microbiológica y microestructural de los catéteres urinarios permanentes y su asociación con la prevención de la infección del tracto urinario. Método: Transversal, de junio a diciembre de 2020, en el que se recolectaron 42 puntas de sonda urinaria permanente y muestras de orina estéril para análisis de cristales en microscopía óptica y biopelículas en microscopía electrónica de barrido. Se realizaron análisis de cultivo y especificación del tipo de bacteria. Resultados: Se encontró que el 35,71% de las muestras presentaban biopelícula madura adherida a la punta del catéter. Se destacaron las biopelículas de Proteus mirabilis, Enterococcus faecalis, Staphylococcus epidermidis, Enterococcus faecium y Enterobacter cloacae. La presencia de cristales de fosfato de magnesio-amonio se asoció con la presencia de infección del tracto urinario y con Proteus mirabilis. Hubo una asociación significativa (p = 0,001) entre el uso de antibióticos profilácticos versus urocultivo >105 UFC/mL. Conclusión: Los análisis contribuyeron a la práctica clínica, ya que refuerzan el desarrollo de estrategias efectivas y monitoreadas sobre cultivos y prevención de la infección del tracto urinario asociada a los catéteres urinarios permanentes.

RESUMO Objetivo: Analisar a parte microbiológica e microestrutural dos cateteres vesicais de demora e sua associação com a prevenção de infecção do trato urinário. Método: Transversal, entre junho e dezembro de 2020, em que foram coletadas 42 pontas cateteres vesicais de demora e amostras de urina estéril para análise de cristais em microscopia óptica e de biofilmes em microscopia eletrônica de varredura. Fez-se analise de cultura e especificação do tipo de bactérias. Resultados: Verificou-se que 35,71% das amostras apresentaram o biofilme maduro aderido à ponta do cateter. Destacaram-se biofilmes de Proteus mirabilis, Enterococcus faecalis, Staphylococcus epidermidis, Enterococcus faecium e Enterobacter cloacae. A presença do cristal magnésio-amônio-fosfato foi associada à presença de infecção do trato urinário e ao Proteus mirabilis. Verificou-se associação significativa (p = 0,001) entre o uso de antibiótico profilático versus a urocultura >105 UFC/mL. Conclusão: As análises contribuíram para a prática clínica, pois reforçam a elaboração de estratégias efetivas e monitoradas sobre culturas e prevenção de infecção do trato urinário associada ao cateter vesical de demora.

Marginal misfit of heat-pressed milled wax-pattern and CAD/CAM crowns and its effect on stress distribution in implant-supported rehabilitations

Aim: To compare the marginal fit of lithium disilicate CAD/CAM crowns and heat-pressed crowns fabricated using milled wax patterns, and evaluate its effect on stress distribution in implantsupported rehabilitation. Methods: A CAD model of a mandibular first molar was designed, and 16 lithium disilicate crowns (8/group) were obtained. The crown-prosthetic abutment set was evaluated in a scanning electron microscopy. The mean misfit for each group was recorded and evaluated using Student's t-test. For in silico analysis, a virtual cement thickness was designed for the two misfit values found previously, and the CAD model was assembled on an implant-abutment set. A load of 100 N was applied at 30° on the central fossa, and the equivalent stress was calculated for the crown, titanium components, bone, and resin cement layer. Results: The CAD/CAM group presented a significantly (p=0.0068) higher misfit (64.99±18.73 µm) than the heat-pressed group (37.64±15.66 µm). In silico results showed that the heat-pressed group presented a decrease in stress concentration of 61% in the crown and 21% in the cement. In addition, a decrease of 14.5% and an increase of 7.8% in the stress for the prosthetic abutment and implant, respectively, was recorded. For the cortical and cancellous bone, a slight increase in stress occurred with an increase in the cement layer thickness of 5.9% and 5.7%, respectively. Conclusion: The milling of wax patterns for subsequent inclusion and obtaining heat-pressed crowns is an option to obtain restorations with an excellent marginal fit and better stress distribution throughout the implant-abutment set

Ultrastructural aspects of the skin in lipoid proteinosis (Urbach-Wiethe disease)

Abstract Lipoid proteinosis is a rare autosomal recessive disease, characterized by hyaline deposits of PAS-positive material in tissues due to mutations in the ECM1 gene. This study evaluated the ultrastructure of the skin of a 6-year-old child affected by this condition. The light microscopy identified PAS-positive hyaline deposits, which were more intense in the papillary dermis. Scanning electron microscopy of the dermis showed a compact papillary dermis and fibrillar deposits in the middle dermis. Transmission electron microscopy clearly showed the deposition of fibrillar material in the dermis, forming clusters adherent to elastic fibers, between the collagen bundles and the collagen fibers, and also filling up the cytoplasm of dermal fibroblasts.

Transmission and scanning electron microscopy of cutis rhomboidalis

Abstract Cutis rhomboidalis nuchae was assessed in a 65-year-old patient. Optical microscopy showed basophilic agglomerations in the reticular dermis with decreased elastic fibers. Trans- mission electron microscopy showed elongated, curved and fragmented structures, and in their interior the presence of electron-dense lumps was reduced and irregular, similar to modified elastic fibers, whereas the collagen fibers had a normal aspect. Scanning electron microscopy showed deposits between the bundles of collagen, resembling pebbles or stones. These findings demonstrate that, at one stage of the disease, the collagen remains normal and the alterations are seen in the elastic tissue.

Multiple myeloma presenting as acute tubulointerstitial nephritis

Background Acute tubulointerstitial nephritis (ATIN) is a very rare paraneoplastic manifestation in patients with multiple myeloma (MM). It is an uncommon pattern of renal disease in such patients. Case presentation We report a case of an 82-year-old male who was admitted with acute kidney injury. Renal biopsy showed typical findings of light chain-associated ATIN with scattered inflammatory cells in the interstitium and associated active tubulitis. No other common manifestations of MM were present at the time of presentation, including hypercalcemia, hyperuricemia, proteinuria, bone pain or lytic bone lesions. Subsequent immunoassays revealed significant serum lambda light chain burden and Bence Jones protein in urine. Immunofluorescence demonstrated linear tubular basement membranes with positive staining for lambda light chain (3+). Electron microscopy (EM) further showed interstitial edema and inflammation. All the aforementioned findings are consistent with ATIN and supported the diagnosis of MM. Conclusions In conclusion, light chain-associated ATIN should be considered in the differential diagnosis of acute interstitial nephritis. Henceforth, serum free light chains as well as serum and urine protein electrophoresis should be included in the workup of such patients.

Eficácia de três protocolos de irrigação final para remoção de raspas dentinárias e material obturador em irregularidades simuladas / Effectiveness of three final irrigation protocols for debris and filling removal from simulated irregularities

Objetivos: Avaliar três protocolos de irrigação final para remoção de detritos e material obturador de istmos simulados. Métodos: Setenta e oito pré-molares foram preparados com o sistema WaveOne Gold 45.05. Os dentes foram seccionados longitudinalmente e um istmo padronizado foi confeccionado no terço apical. Seis raízes foram utilizadas como controle negativo. Os espécimes foram randomizados em dois grupos principais (n=36). Trinta e seis raízes tiveram o istmo preenchido com detritos e as outras trinta e seis raízes foram obturadas com guta-percha e cimento endodôntico, por meio da técnica híbrida de Tagger. Cada grupo foi dividido em três subgrupos (n=12), de acordo com o protocolo de irrigação final: Easy Clean; irrigação ultrassônica passiva (PUI); e XP Clean. A ativação do NaOCl 2,5% pelo Easy Clean foi realizada em três ciclos de vinte segundos; e pelo XP Clean, por um minuto em movimento reciprocante e contínuo, respectivamente. No grupo PUI, o irrigante foi ativado em três períodos de vinte segundos. Resultados: Não foi encontrada associação entre os escores de remoção de detritos e os protocolos de irrigação (p=0,165). Foi observada associação entre os escores de remoção do material obturador e os protocolos de irrigação final (p<0,05). Conclusões: Os protocolos de irrigação final foram efetivos para a remoção de detritos, mas não para remoção de material obturador de istmos no terço apical (AU).

This study aimed to assess three final irrigation protocols on debris and filling removal from simulated irregularities. Methods: Seventy-eight mandibular premolars were prepared with WaveOne Gold system 45.05, splitted longitudinally, and a standardized groove was performed in the apical portion of the canals. Six roots served as negative control. The roots were randomly divided into two main groups (n = 36). The grooves were filled with dentin debris in thirty six roots. The others thirty-six were filled with gutta-percha and endodontic sealer using Tagger hybrid technique. Each main group was then divided into three groups (n = 12) according to the final irrigation protocol: Easy Clean, passive ultrasonic irrigation (PUI), and XP Clean. In Easy Clean 2.5% NaOCl activation was performed for 3 cycles of 20 seconds and XP Clean for one minute under reciprocating and continuous rotary motion and continuous rotary motion, respectively. In the PUI group, the irrigant was activated in three periods of 20 seconds. Results: No association was found among the scores of debris removal and the irrigation protocols (p = .165). An association was observed among the filling material removal scores and irrigation protocols (p< .05). Conclusion: Easy Clean, PUI and XP Clean were effective for dentin debris removal, but did not for filling material from artificial grooves in the apical third (AU).

Aislamiento y caracterización de una cepa temprana de SARS-CoV-2 durante la epidemia de 2020 en Medellín, Colombia / Isolation and characterization of an early SARS-CoV-2 isolate from the 2020 epidemic in Medellín, Colombia

Introducción. El nuevo coronavirus causante de un brote de enfermedad respiratoria aguda en China en diciembre de 2019 se identificó como SARS-CoV-2. La enfermedad, denominada COVID-19, fue declarada pandemia por la Organización Mundial de la Salud (OMS). El primer caso de COVID-19 en Colombia se reportó el 6 de marzo de 2020; en este estudio se caracterizó un aislamiento temprano del virus SARS-CoV-2 de una muestra recolectada en abril de 2020. Objetivos. Describir y caracterizar una cepa temprana a partir de un aislamiento de SARS-CoV-2 durante la pandemia en Colombia. Materiales y métodos. Se obtuvo una muestra de un paciente con COVID-19 confirmada por qRT-PCR; la muestra fue inoculada en diferentes líneas celulares hasta la aparición del efecto citopático. Para confirmar la presencia de SARS-CoV-2 en el cultivo, se utilizó la qRT-PCR a partir de los sobrenadantes, la inmunofluorescencia indirecta (IFI) en células Vero-E6, así como microscopía electrónica y secuenciación de nueva generación (next-generation sequencing). Resultados. Se confirmó el aislamiento de SARS-CoV-2 en células Vero-E6 por la aparición del efecto citopático tres días después de la infección, así como mediante la qRT-PCR y la IFI positiva con suero de paciente convaleciente positivo para SARS-CoV-2. Además, en las imágenes de microscopía electrónica de trasmisión y de barrido de células infectadas se observaron estructuras compatibles con viriones de SARS-CoV-2. Por último, se obtuvo la secuencia completa del genoma, lo que permitió clasificar el aislamiento como linaje B.1.5. Conclusiones. La evidencia presentada en este artículo permite confirmar el primer aislamiento de SARS-CoV-2 en Colombia. Además, muestra que esta cepa se comporta en cultivo celular de manera similar a lo reportado en la literatura para otros aislamientos y que su composición genética está acorde con la variante predominante en el mundo. Finalmente, se resalta la importancia que tiene el aislamiento viral para la detección de anticuerpos, para la caracterización genotípica y fenotípica de la cepa y para probar compuestos con potencial antiviral.

Introduction: SARS-CoV-2 has been identified as the new coronavirus causing an outbreak of acute respiratory disease in China in December, 2019. This disease, currently named COVID-19, has been declared as a pandemic by the World Health Organization (WHO). The first case of COVID-19 in Colombia was reported on March 6, 2020. Here we characterize an early SARS-CoV-2 isolate from the pandemic recovered in April, 2020. Objective: To describe the isolation and characterization of an early SARS-CoV-2 isolate from the epidemic in Colombia. Materials and methods: A nasopharyngeal specimen from a COVID-19 positive patient was inoculated on different cell lines. To confirm the presence of SARS-CoV-2 on cultures we used qRT-PCR, indirect immunofluorescence assay, transmission and scanning electron microscopy, and next-generation sequencing. Results: We determined the isolation of SARS-CoV-2 in Vero-E6 cells by the appearance of the cytopathic effect three days post-infection and confirmed it by the positive results in the qRT-PCR and the immunofluorescence with convalescent serum. Transmission and scanning electron microscopy images obtained from infected cells showed the presence of structures compatible with SARS-CoV-2. Finally, a complete genome sequence obtained by next-generation sequencing allowed classifying the isolate as B.1.5 lineage. Conclusion: The evidence presented in this article confirms the first isolation of SARS-CoV-2 in Colombia. In addition, it shows that this strain behaves in cell culture in a similar way to that reported in the literature for other isolates and that its genetic composition is consistent with the predominant variant in the world. Finally, points out the importance of viral isolation for the detection of neutralizing antibodies, for the genotypic and phenotypic characterization of the strain and for testing compounds with antiviral potential.

Virus Isolation from the First Patient with SARS-CoV-2 in Korea

Novel coronavirus (SARS-CoV-2) is found to cause a large outbreak started from Wuhan since December 2019 in China and SARS-CoV-2 infections have been reported with epidemiological linkage to China in 25 countries until now. We isolated SARS-CoV-2 from the oropharyngeal sample obtained from the patient with the first laboratory-confirmed SARS-CoV-2 infection in Korea. Cytopathic effects of SARS-CoV-2 in the Vero cell cultures were confluent 3 days after the first blind passage of the sample. Coronavirus was confirmed with spherical particle having a fringe reminiscent of crown on transmission electron microscopy. Phylogenetic analyses of whole genome sequences showed that it clustered with other SARS-CoV-2 reported from Wuhan.

Bactericidal and Smear Layer Removal Efficacy of Herbal Alternatives Against Enterococcus Faecalis Dentinal Biofilm - An ex-vivo Study

Abstract Objective: To assess the antibacterial and smear layer removal ability of Trigonella foenum, Syzygium cumini, Terminalia chebula seed extracts against E. faecalis dentinal biofilm. Material and Methods: Agar well diffusion, micro broth dilution assay and time-kill curve assay were performed to determine the antibacterial activity. The ability of the herbal extracts to remove the smear layer on the root canal surface was assessed by scanning electron microscopy. Results: Antibacterial activity was observed for the extracts of S. cumini and T. chebula on E. faecalis dentinal biofilm and its planktonic counterparts. The smear layer was efficiently removed by the seed extracts of T. chebula alone. Seed extracts of T. foenum neither possessed antibacterial effect nor smear layer removal ability. Conclusion: The extracts of T. chebula seeds may replace conventional irrigant due to its antibacterial properties and smear layer removing the ability. The extracts of S. cumini may be used as an intracanal medicament as it exhibited a bactericidal effect against the E. faecalis dentinal biofilm following 18 hours of incubation.

Scanning electron microscopy assessment of the load-bearing capacity of cad/cam-fabricated molar crowns

Abstract Although fiber-reinforced composites are commonly used in dental practice, whether fiber-reinforced crowns and fixed partial dentures can be used as definitive prostheses remains to be determined. This study used scanning electron microscopy to evaluate the load-bearing capacity of non-reinforced and fiber-reinforced composite (FRC) molar crowns prepared by computer-aided design/computer-aided manufacturing (CAD/CAM). The crowns were fabricated from three empirical FRC blocks, one empirical composite block, and one commercial ceramic block. The FRC resin was prepared by mixing BaO silicate particles, E-glass fiber, and dimethacrylate resin. Specimens were divided into five groups (n = 10), differing in the amounts of filler, resin, and fiber. Crowns were statically loaded until fracture. One-way analysis of variance and Tukey's post hoc multiple comparison tests were used for statistical analyses. The groups showed significant differences in load-bearing capacity; empirical bidirectional FRC resin blocks had the highest capacity, while commercial ceramic blocks had the lowest capacity. Molar crowns formed from FRC resin blocks had higher load-bearing capacity compared to non-reinforced composite resin and ceramic blocks. These results show that fiber reinforcement increased the load-bearing capacity of molar crowns.

Bond stability of universal adhesives applied to dentin using etch-and-rinse or self-etch strategies

Abstract This study evaluated the immediate and 6-month dentin bond strength of universal adhesives used in etch-and-rinse or self-etch bonding strategies. The adhesives tested were Ambar Universal, G-Bond, Single Bond Universal, Tetric N-Bond Universal, and Ybond Universal. Gold standard adhesives (Scotchbond Multipurpose Plus and Clearfil SE Bond) were controls. Microtensile dentin bond strength (n=5 teeth), pH, and C=C conversion (n=3) were evaluated. Data were analyzed at α=0.05. All adhesives showed differences in pH. Ybond had intermediately strong aggressiveness, whereas the others were ultra-mild. The C=C conversion was different in most adhesives. In the etch-and-rinse strategy, all adhesives showed similar results generally except for G-Bond, which had lower bond strength than most adhesives. G-Bond and Tetric-N-Bond showed lower bond strengths after 6 months compared with 24 h, whereas the other adhesives had stable dentin bonds. In the self-etch strategy, G-Bond had lower bond strength than most adhesives. After 6 months, Ambar was the only adhesive showing lower dentin bond strength compared with 24 h. Most adhesives had discreet drops in bond strength during aging when used in the self-etch strategy. The failure modes were also material dependent, with a general pattern of increased adhesive and/or pre-testing failures after storage. In conclusion, the bonding performance of universal adhesives to dentin is material dependent. Most adhesives had stable dentin bonds with results comparable to the gold standard materials, particularly when applied in the self-etch mode. In general, it seems the use of universal adhesives in dentin should not be preceded by phosphoric acid etching.

Resumo Este estudo avaliou a resistência de união à dentina imediata e após 6 meses de adesivos universais utilizando estratégias de união convencional ou autocondicionante. Os adesivos testados foram Ambar Universal, G-Bond, Single Bond Universal, Tetric N-Bond Universal e Ybond Universal. Adesivos padrão-ouro (Scotchbond Multipurpose Plus e Clearfil SE Bond) foram os controles. Resistência de união à microtração na dentina (n=5 dentes), pH e conversão de C=C (n=3) foram avaliados. Os dados foram analisados considerando α=0,05. Todos os adesivos mostraram diferenças de pH comparados aos demais. Ybond Universal teve agressividade intermediária forte, enquanto os outros foram ultramoderados. A conversão de C=C foi diferente em quase todos adesivos. No modo convencional, em geral todos os adesivos mostraram resultados similares exceto G-Bond, que teve menor resistência de união que a maioria dos adesivos. G-Bond e Tetric-N-Bond mostraram resistências de união menores após 6 meses comparados a 24 h, enquanto os outros adesivos apresentaram estável união à dentina. No modo autocondicionante, G-Bond teve menor resistência de união que quase todos os adesivos. Após 6 meses, Ambar foi o único adesivo mostrando menor resistência de união à dentina comparado a 24 h. A maioria dos adesivos teve discreta queda na resistência de união durante o envelhecimento quando usados na estratégia autocondicionante. Os modos de falha também foram material dependentes, com um padrão geral de mais falhas adesivas e/ou pré-teste após o armazenamento. Em conclusão, o desempenho de união de adesivos universais à dentina é material dependente. Grande parte dos adesivos apresentou estável união à dentina com resultados comparáveis ao materiais padrão-ouro, particularmente quando aplicados no modo autocondicionante. Em geral, parece que o uso de adesivos universais em dentina não deve ser precedido por condicionamento com ácido fosfórico.

Efeito de diferentes protocolos de irrigação final na remoção da smear layer / Effect of different protocols of final irrigation on smear layer removal

Objetivo: esse estudo avaliou o efeito de protocolos de irrigação final, associados ao uso de EDTA e QMix, na remoção de smear layer. Métodos: foram utilizados 40 dentes humanos com canal único. Os canais foram instrumentados com sistema ProTaper Universal SX-F3. As substâncias químicas utilizadas durante o preparo foram hipoclorito de sódio a 5,25% (NaOCl) ou clorexidina a 2% (CHX) gel. Terminado o preparo, os dentes foram divididos em oito grupos, de acordo com os irrigantes: G1) NaOCl 5,25% + EDTA 17% + NaOCl 5,25%; G2) NaOCl 5,25% + EDTA 17% + água destilada (AD); G3) NaOCl 5,25% + QMix + NaOCl 5,25%; G4) NaOCl 5,25% + QMix + AD; G5) CHX 2% gel + EDTA 17% + CHX 2% solução; G6) CHX 2% gel + EDTA 17% + AD; G7) CHX 2% gel + QMix + CHX 2% solução e G8) CHX 2% gel + QMix + AD. As amostras foram avaliadas por microscopia eletrônica de varredura ambiental, antes e após os protocolos de irrigação final. As imagens foram classificadas por escores, em relação à presença de smear layer, e os dados foram analisados pelos testes de Kruskal-Wallis e de Mann-Whitney. Resultados: o G1 mostrou os melhores resultados em relação à remoção de smear layer (p < 0,05). A CHX gel 2% mostrou menor formação de smear layer, quando comparada ao NaOCl, após o preparo biomecânico; e o NaOCl apresentou melhor limpeza como irrigante final (p < 0,05). Conclusões: o NaOCl como irrigante final, combinado ao EDTA, mostrou melhor capacidade de remoção da smear layer (AU).

Introduction: This study evaluated the effect of different final irrigation protocols using EDTA and QMix on smear layer removal. Methods: The root canals of 40 single-rooted human teeth were prepared with ProTaper Universal SX - F3. The substances used were 5.25% sodium hypochlorite (NaOCl), 2% chlorhexidine gel (chlorhexidine), 2% chlorhexidine solution and distilled water. The teeth were divided into 8 groups, according to the irrigant used: G1: 5.25% NaOCl + 17% EDTA + 5.25% NaOCl; G2: 5.25% NaOCl + 17% EDTA + distilled water; G3: 5.25% NaOCl + QMix + 5.25% NaOCl; G4: 5.25% NaOCl + QMix + DW; G5: 2% chlorhexidine gel + 17% EDTA + 2% chlorhexidine solution; G6: 2% chlorhexidine gel + 17% EDTA + distilled water; G7: 2% chlorhexidine gel + QMix + 2% chlorhexidine solution; and G8: 2% chlorhexidine gel + QMix + distilled water. Samples were evaluated under environmental scanning electron microscopy (ESEM) before and after irrigation. ESEM images were classified according to smear layer scores, and the Kruskal-Wallis and Mann-Whitney tests were used for statistical analyses. Results: Group 1 had the best results for smear layer removal (p<0.05). Smear layer formation was lower when 2% chlorhexidine gel was used after cleaning and shaping than when the irrigant was 5.25% NaOCl, and 5.25% NaOCl had the best cleaning ability as a final irrigant. Conclusion: 5.25% NaOCl combined with EDTA was the best final irrigant for smear layer removal (AU).

Scanning electron microscopy of dermatofibroma

Abstract: Dermatofibroma is a proliferation of spindle cells located in the dermis. We used scanning electron microscopy to examine two histologically confirmed lesions and observed preserved collagen bundles in the perilesional area. In the lesional area, the collagen was denser, without formation of bundles. Higher magnification showed collagen with mesh-like appearance similar to stretched tufts of cotton. Very high magnification evidenced the tufts of cotton and spindle cells measuring 2 to 12 microns.