The Importance of the Density Functional Theory Exchange-Correlation Hartree-Fock Term in Magnetic Resonance: Application to an Aqueous Environment.

Within the framework of Density Functional Theory (DFT), the relevance of the term Hartree-Fock exchange (HFE) for a variety of molecular properties is a critical point. For this reason, we spend efforts to understand these relationships in nuclear magnetic resonance (NMR) parameters in a water solvent. This work takes advantage of the appropriate aug-cc-pVTZ-J basis set and the Minnesota family of DFT methods, which consider different portions of HFE contributions. With regard to solvent participation, the results are based on a sequential Monte Carlo/Quantum Mechanics procedure, which builds the structures of the liquid under realistic thermodynamic conditions. Compared to the accurate results of second-order polarization propagator approximation (SOPPA) and experimental data, all NMR parameters show a huge dependence on the size of the HFE contribution. For instance, the inclusion of this term in 1JOH and 2JHH indirect spin-spin couplings does vary with 49.661 and 25.459 Hz, respectively. The M06-HF method accounts for 100% of HFE and better matches the σO and σH shielding constants. On the other hand, 1JOH and 2JHH demand a medium contribution (54% of HFE), the best description being associated with the M06-2X method. Thus, the dependence varies regarding the phenomenology of the property in focus and the order for independent treatments. For elements that participate in hydrogen bonds simultaneously as donor and acceptor actors, the results indicate that explicit solvent molecules must be considered in the quantum mechanical calculations for better modeling of paramagnetic shielding constants.

Effect of solvent, temperature and pressure on the stability of chiral and perovskite metal formate frameworks of [NH2NH3][M(HCOO)3] (M = Mn, Fe, Zn).

We report the synthesis, crystal structure, and thermal, Raman, infrared and magnetic properties of [NH2NH3][M(HCOO)3] (HyM) compounds (M = Mn, Zn, Fe). Our results show that synthesis from methanol solution leads to perovskite polymorphs while that from 1-methyl-2-pyrrolidinone or its mixture with methanol allows obtaining chiral polymorphs. Perovskite HyFe, chiral HyFe and chiral HyMn undergo phase transitions at 347, 336 and 296 K, respectively, with symmetry changes from Pnma to Pna21, P63 to P212121 and P63 to P21. X-ray diffraction and Raman studies show that the phase transitions are governed by dynamics of the hydrazinium ions. Low-temperature magnetic studies show that these compounds exhibit magnetic ordering below 9-12.5 K. Since the low-temperature structures of chiral HyMn and perovskite HyFe are polar, these compounds are possible multiferroic materials. We also report high-pressure Raman scattering studies of chiral and perovskite HyZn, which show much larger stiffness of the latter phase. These studies also show that the ambient pressure polar phases are stable up to at least 1.4 and 4.1 GPa for the chiral and perovskite phase, respectively. Between 1.4 and 2.0 GPa (for chiral HyZn) and 4.1 and 5.2 GPa (for perovskite HyZn) pressure-induced transitions are observed associated with changes in the zinc-formate framework. Strong broadening of Raman bands and the decrease in their number for the high-pressure phase of chiral HyZn suggest that this phase is disordered and has higher symmetry than the ambient pressure one.

O papel da superfície moderadamente rugosa e quimicamente modificada em um protocolo de carga precoce: uma revisão de literatura / The role of a moderately rough and chemically modified implant surface in an early loading protocol: a literature review

Realizar uma revisão de literatura, com base nas evidências científicas atualmente disponíveis, a respeito dos períodos iniciais do reparo ósseo em torno de implantes com superfície moderadamente rugosa e quimicamente modificada (MRQM). Para a revisão da literatura, foi realizada uma pesquisa eletrônica via PubMed, utilizando, para a seleção dos artigos, uma combinação das palavras-chave ‘osseointegration’, ‘bone-to-implant contact’, ‘wettability’, ‘chemically modified surface’ e ‘bone healing’. Foram considerados estudos experimentais in vitro, em modelos animais e em humanos, abrangendo as características físico-químicas, mecanismos biológicos e eventos histológicos iniciais relacionados à superfície MRQM. Estudos experimentais reportam uma maior aposição óssea e ancoragem à superfície quimicamente modificada, nos estágios iniciais do reparo ósseo, em modelos animais. Esses resultados experimentais foram validados por estudos clínicos prospectivos, estudos de mensuração da estabilidade do implante com análise de frequência de ressonância (RFA), perfis de expressão gênica e histológicos temporais em modelos humanos. Dentro das limitações desse estudo da superfície MRQM, é possível sugerir que a alta energia da superfície e molhabilidade aumentada influenciam positivamente na formação óssea nos períodos iniciais do reparo ósseo...

The aim of this study was to accomplish a literature review, based on currently available evidence, about the early periods of bone integration around endosseous implants with moderately rough and chemically modified surface (MRCM). The review was performed through an electronic survey via PubMed, using a combination of keywords, including: osseointegration, bone-to-implant contact, wettability, chemically modified surface and bone healing. Experimental in vitro studies, in animal models and in humans, covering physicochemical characteristics, biological mechanisms and initial histological events related to MRCM implant surface were considered. Experimental studies report higher bone apposition and better bone anchorage to MRCM surfaces during early stages of bone healing in animal models. These experimental results were validated by prospective clinical studies, studies measuring implant stability with resonance frequency analysis, gene expression profiles and temporal histological studies in human models. Within the limitations of this MRCM surface study, it is suggested that high surface energy and increased wettability positively influence bone formation in the initial periods of bone repair...

Elevação bilateral de seio maxilar utilizando cem porcento de biomaterial aloplástico, para posterior reabilitaçãode maxila atrófica. Follow-up tomográfico de cinco anos / Bilateral sinus floor augmentation using one hundred percent alloplastic biomaterial for later rehabilitation of atrophic maxilla. A 5-year tomographic follow-up

A restauração implantossuportada bem-sucedida passa por um planejamento prévio, abordando as variáveis clínicas específicas para cada caso. Maxilas severamente atróficas representam um desafio para reabilitação com próteses fixas, haja vista que o paciente não possui a quantidade mínima necessária de altura óssea na região posterior para a instalação de implantes no local preconizado pelo enceramento diagnóstico. Objetivo: o presente estudo tem como objetivo relatar um caso de reabilitação bucal com prótese total implantossuportada por meio de elevação bilateral de seio maxilar, utilizando 100% de biomaterial aloplástico para posterior instalação de implantes dentários, com cinco anos de follow-up clínico e tomográfico. Métodos: a utilização de um substituto ósseo sintético (fosfato de cálcio bifásico) elimina qualquer risco potencial de transmissão de microrganismos e reduz o número de sítios cirúrgicos, haja vista que dispensa a coleta de osso autógeno para enxertia. Como a altura óssea subantral residual chegava a ser inferior a 1mm, um procedimento de elevação de seio maxilar bilateral, por meio da técnica da janela lateral, foi planejado para oito meses antes da instalação de oito implantes, que serviriam de retenção para uma prótese total implantossuportada, a ser instalada 60 dias após a cirurgia de colocação dos implantes. Conclusão: há evidências, tanto na literatura científica quanto no caso relatado,que de que a utilização de 100% biomaterial aloplástico para aumento vertical de maxila atrófica por meio de levantamento do assoalho do seio maxilar consiste em uma alternativa ao uso do enxerto autógeno, tornando-se uma solução eficiente e de menor morbidade...

Successful implant rehabilitation relies on previous planning that addresses thespecific clinical variables of each case. Fixed-prosthesis rehabilitation of severely atrophic maxilla is a challenge, given that patients do not present with minimal posterior bone height required for implant placement at the site recommended by diagnostic wax-up. Objective: The present study aims at reporting a case of implant-supported complete denture oral rehabilitation performed by means of bilateral maxillary sinus lift with 100% alloplastic biomaterial for subsequent implant placement, with a 5-year clinicaland tomographic follow-up. Methods: The use of synthetic bone substitutes (biphasic calcium phosphate) not only eliminates potential risks of contamination, but also reduces the number of surgical sites, given that it does not require autogenous bone to be harvested for grafting. Subantral residual bone height was less than 1 mm, therefore, bilateral maxillary sinus lift carried out by means of the lateral window approach was planned to be performed eight months before placement of eight implants. These implants would give support to a complete denture installed 60 days after implant placement surgery. Conclusion:Both scientific literature and the case reported herein evince that the use of 100% alloplastic biomaterialfor vertical augmentation of atrophic maxilla by means of maxillary sinus lift is an efficient alternative to replace autograft due to presenting lower morbidity rates...

Raman and IR studies of pressure- and temperature-induced phase transitions in [(CH2)3NH2][Zn(HCOO)3].

Temperature- and pressure-dependent studies of Raman and IR spectra have been performed on azetidinium zinc formate, [(CH2)3NH2][Zn(HCOO)3]. Vibrational spectra showed distinct anomalies in mode frequencies and bandwidths near 250 and 300 K, which were attributed to structural phase transitions associated with the gradual freezing of ring-puckering motions of the azetidinium cation. Pressure-dependent studies revealed a pressure-induced transition near 0.4 GPa. Raman spectra indicate that the structure of the room-temperature intermediate phase observed near 0.4 GPa is the same as the monoclinic structure observed at ambient pressure below 250 K. The second phase transition was found near 2.4 GPa. This transition has strong first-order character and is associated with strong distortion of both the zinc formate framework and azetidinium cations. The last phase transition was found near 7.0 GPa. This transition leads to lowering of the symmetry and further distortion of the zinc formate framework, whereas the azetidinium cation structure is weakly affected.

Reabilitação de maxila atrófica sem uso de abordagem reconstrutiva: relato de caso / Rehabilitation of atrophic maxilla without a reconstructive approach:a case report

A reabilitação bucal de pacientes edêntulos, por meio do uso de próteses totais fixas, comumente envolve procedimentos reconstrutivos prévios, haja vista que o rebordo ósseo residual não apresenta as dimensões mínimas requeridas para a instalação de implantes de diâmetro regular na região planejada. Fatores como o custo elevado e o medo de procedimentos cirúrgicos adicionais fazem com que alguns idosos, mesmo insatisfeitos com a instabilidade da prótese removível, resistam ao tratamento com implantes dentários. Objetivo: dessa forma, o presente estudo tem como objetivo relatar um caso de reabilitação bucal com prótese total implantossuportada, por meio da instalação de implantes de diâmetro reduzido (3,3mm) em maxila severamente atrófica, sem a utilização de enxertos ou abordagens reconstrutivas. Os 8 implantes, instalados com abordagem palatina nos sítios previamente planejados, permaneceram submersos por 45 dias, quando foi dado o início da adequação gengival e etapas protéticas. A prótese definitiva foi instalada 65 dias após a cirurgia. Nenhuma intercorrência foi registrada durante 6 meses de acompanhamento. Nota-se que os implantes de diâmetro reduzido surgem como uma alternativa simples e rápida à realização de procedimentos de aumento ósseo horizontal, e podem ser utilizados com segurança como forma de retenção para próteses fixas, tornando-se uma solução eficiente e de menor custo para pacientes edêntulos que desejam reduzir os problemas relacionados à instabilidade de próteses totais removíveis...

Oral rehabilitation of edentulous patients using fixed prostheses commonlyinvolves previous reconstructive procedures, since the residual ridge does not have the minimumdimensions required for installation of standard diameter implants in the planned site. Factors suchas high cost and fear of additional surgical procedures make some elderly, even those who are dissatisfiedwith the instability of removable prosthesis, hesitant to treatment with dental implants.Objective: This study aims to report a case of oral rehabilitation with fixed dentures supported byimplants of reduced diameter (3.3 mm) in severely atrophic maxilla without the use of grafts or reconstructiveapproaches. The eight implants, installed with palatal approach at previously plannedsites, remained submerged for 45 days when soft tissue adjustment and prosthetic procedures werestarted. The definitive prosthesis was installed 65 days after surgery. Results: No intercurrence wasregistered after 6 months of follow-up. Small diameter implants appear as a simple and fast alternativefor horizontal bone augmentation procedures. Additionally, they can be safely used for retentionof fixed prosthesis, and prove to be an efficient and low-cost solution for edentulous patientswho wish to minimize problems related to the instability of removable dentures...

Reabilitação com implantes dentários em paciente diagnosticado com epidermólise bolhosa distrófica dominante / Rehabilitation with dental implants of patient diagnosed with dominant dystrophic epidermolysis bullosa

Epidermólise bolhosa (EB) é caracterizada pela fragilidade excessiva da pele e membranas mucosas com formação de bolhas recorrentes, erosões e cicatrizes secundárias a traumas mecânicos e fricção. As manifestações bucais da EB dificultam a higienização e a realização de tratamentos restauradores, podendo levar à perda precoce da dentição, gerando quadros de edentulismo. O presente estudo relata um caso de reabilitação oral mandibular de paciente diagnosticado com EB distrófica dominante, utilizando prótese total implantossuportada, alternativa às próteses removíveis e implantomucossuportadas responsáveis por gerar fricção sobre a mucosa oral. Optou-se pela extração dos dentes remanescentes comprometidos e restauração da função mastigatória e estética do paciente, com uma prótese total suportada por quatro implantes instalados na região interforaminal. Foram realizados ajustes específicos à técnica anestésica e protocolo cirúrgico com o intuito de minimizar o trauma aos tecidos moles. A prótese definitiva foi instalada sete dias após a cirurgia. Com seis meses de acompanhamento, a paciente relatou melhora significativa da função mastigatória e redução das lesões orais, o que sugere que implantes dentários podem ser utilizados como forma de retenção para reabilitação protética em pacientes diagnosticados com EB, conferindo-lhes uma melhor qualidade de vida.

Epidermolysis bullosa (EB) is characterized by excessive fragility of the skin and mucosa, with repeated blistering, erosions and scar formation secondary to trauma and mechanical friction.The oral manifestations of EB hinder oral cleaning and restorative treatments, which may lead to early tooth loss. The present study reports a case of mandibular oral rehabilitation of a patient diagnosed with dominant dystrophic EB through the use of implant-supported prosthesis, avoiding dentures and overdentures that create frictioning on the oral mucosa. Compromised remaining teeth were extracted. Then, masticatory and esthetic functions were restored with a complete denture supported by 4 implants placed in the interforaminal region. Specific adjustments were made to the anesthetic and surgical protocol in order to minimize trauma to the soft tissues. The definitive prosthesis was installed 7 days after surgery. At 6 months of follow-up, the patient reported significant improvement on masticatory function and reduction of oral lesions, suggesting that dental implants can be successfully used as a means of retention for prosthetic rehabilitation in patients diagnosed with EB, giving them a better quality of life.