Localized mechanics of dentin self-etching adhesive system

The bond strength of composite resins (CRs) to dentin is influenced by the interfacial microstructure of the hybrid layer (HL) and the resin tags (TAG). The contemporary self-etching primer adhesive systems overcame the inconvenient of the etch-and-rinse protocol. Studies, however, have demonstrated that HL thickness and TAG length vary according to the wetting time and additional use of acid-etching prior to self-etching primers. This study investigated the localized stress distribution in the HL and the dentin/adhesive interface. Two HL thicknesses (3 or 6 µm), two TAG lengths (13 or 17 µm) and two loading conditions (perpendicular and oblique-25º) were investigated by the finite element (FE) analysis. Five two-dimensional FE models (M) of a dentin specimen restored with CR (38 x 64 µm) were constructed: M1 - no HL and no TAG; M2 - 3 µm of HL and 13 µm of TAG; M3 - 3 µm of HL and 17 µm of TAG; M4 - 6 µm of HL and 13 µm of TAG; and M5 - 6 µm of HL and 17 µm of TAG. Two distributed loadings (L) (20N) were applied on CR surface: L1 - perpendicular, and L2 - oblique (25º). Fixed interfacial conditions were assigned on the border of the dentin specimen. Ansys 10.0 (Ansys®, Houston, PA, USA) software was used to calculate the stress fields. The peak of von Mises (sigmavM) and maximum principal stress (sigmamax) was higher in L2 than in L1. Microstructures (HL and TAG) had no effect on local stresses for L1. Decreasing HL decreased sigmavM and sigmamax in all structures for L2, but the TAG length had influence only on the peributular dentin. The thickness of HL had more influence on the sigmavM and sigmamax than TAG length. The peritubular dentin and its adjacent structures showed the highest sigmavM and sigmamax, mainly in the oblique loading

Late recurrence of Burkitt’s lymphoma in the jaw: numb chin syndrome as the only symptom

The Numb Chin Syndrome (NCS) is defined as facial and oral numbness restricted to the mental nerve’s distribution involving the lower lip, skin of the chin, or gingiva of the lower anterior teeth. Hypoesthesia can occur unilaterally or bilaterally. Although this syndrome is rare, its importance is related to the fact that it represents the clinical manifestations of malignant diseases. Breast cancer and non-Hodgkin lymphoma are the most common cause of NCS. The patient, a 58-year-old woman, treated for a Burkitt Lymphoma (BL) nine years ago, described a two-week history of change in sensitivity and pain in the chin region, without relief with the use of analgesics. She had no headache, speech disturbance, dysphagia, visual disturbance, or other neurological symptoms. No surgical intervention has been performed recently. The intraoral examination revealed a healthy oral mucosa and a small area adjacent to the right mental nerve region that was uncomfortable to palpation. No changes were found in the bone trabeculae at cone-beam computed tomography. The contrasted magnetic resonance features made it possible to identify a change in the mandibular body extending to the entire right side, coinciding with the patient’s complaint, indicating a probable mandibular medullary invasion. The patient was submitted to a biopsy to rule out a possible recurrence of BL. The microscopic findings were consistent with the diagnosis of BL. The present report described a very unusual presentation of late recurrent BL nine years after the first treatment, which manifested as an NCS

Stress distribution on dentin-cement-post interface varying root canal and glass fiber post diameters. A three-dimensional finite element analysis based on micro-CT data

Objective: The aim of the present study was to analyze the influence of root canal and glass fiber post diameters on the biomechanical behavior of the dentin/cement/post interface of a root-filled tooth using 3D finite element analysis. Material and Methods: Six models were built using micro-CT imaging data and SolidWorks 2007 software, varying the root canal (C) and the glass fiber post (P) diameters: C1P1-C=1 mm and P=1 mm; C2P1-C=2 mm and P=1 mm; C2P2-C=2 mm and P=2 mm; C3P1-C=3 mm and P=1 mm; C3P2-C=3 mm and P=2 mm; and C3P3-C=3 mm and P=3 mm. The numerical analysis was conducted with ANSYS Workbench 10.0. An oblique force (180 N at 45º) was applied to the palatal surface of the central incisor. The periodontal ligament surface was constrained on the three axes (x=y=z=0). Maximum principal stress (σmax) values were evaluated for the root dentin, cement layer, and glass fiber post. Results: The most evident stress was observed in the glass fiber post at C3P1 (323 MPa), and the maximum stress in the cement layer occurred at C1P1 (43.2 MPa). The stress on the root dentin was almost constant in all models with a peak in tension at C2P1 (64.5 MPa). CONCLUSION: The greatest discrepancy between root canal and post diameters is favorable for stress concentration at the post surface. The dentin remaining after the various root canal preparations did not increase the stress levels on the root

Multivariate analysis of chemical parameters of cocoa: a contribution to origin designation / Análise multivariada de parâmetros químicos do cacau: uma contribuição para a denominação de origem

Brazil has been trying to become a key player in the specialized market through the production of fine chocolate. However, there is still no rules about the chemical quality of cocoa beans that allows it to be grouped by micro-regions. In this context, the objective of this work was to determine some chemical parameters of cocoa samples, aiming to contribute to the creation of the designation of origin for the cocoa produced in the south of Bahia. For this propose, proteins, lipids, total minerals, and fatty acid profile analysis were performed. The results obtained were correlated using multivariate statistical tests. The chemical composition of the cocoa beans, allowed to differentiate samples of cocoa, revealing the formation of three groups of samples. The two main components (lipids and proteins) were analysed together, characterizing the producing region. Regarding the analysis of the fatty acid profile, they showed that the cocoa harvested in the main season presents a higher influence of saturated fatty acids, while in the early season the higher influence is of unsaturated fatty acids. Multivariate techniques were able to group the different types of cocoa according to their chemical profile, helping to create an origin denomination for those produced in Southern Bahia

Biomechanical performance of three fiberglass post cementation techniques: Imaging, in vitro, and in silico analysis

Purpose: The structural integrity of the resin cement layer, the bond strength, and the biomechanical behavior of different fiberglass post cementation techniques were evaluated. Methods: Thirty-three bovine incisors were divided into three groups (n = 11): conventional fiberglass post (CFP), conventional fiberglass post in flared root canals (CFL), and relined fiberglass post (RFP). Six specimens from each group were submitted for high-resolution microcomputed tomography (μCT) to evaluate the integrity and presence/volume of voids at the resin cement layer. Finite element analysis (FEA) of two three-dimensional (3D) models of each group were conducted, one considered ideal (without interface defects) and another containing the conditions identified in the μCT analysis. Push-out bond strength tests were conducted for all specimens. Results: The CFL group had the greatest mean values of void (Thirds cervical: 73.67; middle: 95.67; apical: 47.33) and gap concentration (Thirds cervical: 14.67; middle: 15.83; apical: 8.33) compared with CFP and RFP. A significant difference in bond strength was observed between the cervical (1.33 MPa) and middle thirds (1.85 MPa) compared with the apical third (4.85 MPa) of the CFL. A significant difference was observed in the bond strength in the CFL (1.33 MPa) and RFP (3.29 MPa) in the cervical third, which were statistically similar to the bond strength of the CFP. The tensile stress distributions were similar in most structures, localized in the cervical region on the lingual surface. Conclusions: Structural defects in the interface layer might influence the bond strength and biomechanical behavior under the different fiberglass post cementations.Hoshino I.A.E., Dos Santos P.H., Briso A.L.F., et al. Biomechanical performance of three fiberglass post cementation techniques: Imaging, in vitro, and in silico analysis. Journal of Prosthodontic Research 67, 103 (2023); https://doi.org/10.2186/jpr.JPR_D_21_00253

Cesariana primária em nulíparas – fatores de risco em hospital público universitário

Objetivo: identificar fatores determinantes para risco de cesariana primária em nulíparas. Métodos: estudo de coorte prospectivo desenvolvido em hospital público universitário. Foram incluídas todas primíparas atendidas na emergência obstétrica de dezembro/2006 a junho/2007. Informações sociodemográficas e doenças prévias foram obtidas na admissão; o desfecho principal foi a via de parto. Para análise estatística utilizou-se o modelo de regressão de Poisson e as variáveis com significância de associação ≤ 0,2 entraram no modelo múltiplo. Resultados: as variáveis determinantes da cesariana primária entre nulíparas foram: apresentação fetal não cefálica (RR=2,8; IC95 %=1,9 – 4,2); emergências obstétricas (RR=2,4; IC95 %=1,7 – 3,2); macrossomia fetal presumida (RR=1,9; IC95%=1,2 – 3,2); doenças fetais (RR=1,6; IC95%=1,2 – 2,2); idade gestacional igual ou maior de 40 semanas (RR=1,5; IC95%=1,1 – 2,0); distúrbios hipertensivos (RR=1,33; IC95%=1,01 – 1,76) e idade materna (RR=1,05; IC95%=1,03 - 1,07).  Conclusões: os resultados indicaram que os principais fatores determinantes para cesariana primária são condições potencialmente modificáveis. A apresentação fetal não-cefálica pode ser alterada com utilização mais frequente da versão cefálica externa; a idade gestacional ≥ 40 semanas, com datação criteriosa da gestação e protocolos previamente definidos para indução do parto; a macrossomia fetal presumida, com treinamento em avaliação clínica e/ou ecográfica do peso fetal no termo

Localized mechanics of dentin self-etching adhesive system

The bond strength of composite resins (CRs) to dentin is influenced by the interfacial microstructure of the hybrid layer (HL) and the resin tags (TAG). The contemporary self-etching primer adhesive systems overcame the inconvenient of the etch-and-rinse protocol. Studies, however, have demonstrated that HL thickness and TAG length vary according to the wetting time and additional use of acid-etching prior to self-etching primers. This study investigated the localized stress distribution in the HL and the dentin/adhesive interface. Two HL thicknesses (3 or 6 μm), two TAG lengths (13 or 17 μm) and two loading conditions (perpendicular and oblique-25o) were investigated by the finite element (FE) analysis. Five two-dimensional FE models (M) of a dentin specimen restored with CR (38 x 64 μm) were constructed: Ml - no HL and no TAG; M2 - 3 μm of HL and 13 μm of TAG; M3 - 3 μm of HL and 17 μm of TAG; M4 - 6 μm of HL and 13 μm of TAG; and M5 - 6 μm of HL and 17 μm of TAG. Two distributed loadings (L) (20N) were applied on CR surface: L1 - perpendicular, and L2 - oblique (25°). Fixed interfacial conditions were assigned on the border of the dentin specimen. Ansys 10.0 (Ansys®, Houston, PA, USA) software was used to calculate the stress fields. The peak of von Mises (σvM) and maximum principal stress (σmax) was higher in L2 than in L1. Microstructures (HL and TAG) had no effect on local stresses for L1. Decreasing HL decreased σvM and σmax in all structures for L2, but the TAG length had influence only on the peributular dentin. The thickness of HL had more influence on the σvM and σmax than TAG length. The peritubular dentin and its adjacent structures showed the highest σvM and σmax, mainly in the oblique loading

Fibroadenoma versus Tumor Phyllodes: como diferenciá-los? / Fibroadenoma versus Tumor Phylodes: how to differentiate them?

Objetivo: Avaliar evidências científicas que explanem sobre os critérios diagnósticos que podem ser utilizados para diferenciação entre Tumor Phyllodes e Fibroadenoma. Métodos: A revisão consistiu da busca de artigos disponíveis nas principais bases de dados e foram adotadas as seguintes palavras-chaves: “Fibroadenoma” e “Tumor Phyllodes”. Foram utilizados os seguintes critérios para a seleção: estudos realizados no período de 2008 a 2018, que explanassem sobre as características para um diagnóstico de diferenciação desses Tumores. Foram selecionados 15 artigos que contemplaram os critérios. Resultados: Observou-se que vários estudos utilizaram a deposição de colágeno como um possível marcador de diferenciação, bem como expressão de marcadores moleculares que auxiliam na distinção e servem para observação da progressão da neoplasia. Os exames de imagens podem ser utilizados, mas sofrem variáveis. Enquanto em nível citopatológico e histológico há muita problemática diagnóstica porque os dois tumores têm características semelhantes. Conclusão: As evidências analisadas para uma melhor diferenciação do Tumor Phyllodes e Fibroadenoma, se mostram promissoras, principalmente a nível molecular. Por outro lado, a dificuldade de diferenciação cito e histopatológica, muitas vezes nos exames de imagens, ainda continua presente nos diagnósticos