CaviDB: a database of cavities and their features in the structural and conformational space of proteins.

Proteins are the structural, functional and evolutionary units of cells. On their surface, proteins are shaped into numerous depressions and protrusions that provide unique microenvironments for ligand binding and catalysis. The dynamics, size and chemical properties of these cavities are essential for a mechanistic understanding of protein function. Here, we present CaviDB, a novel database of cavities and their features in known protein structures. It integrates the results of commonly used cavity detection software with protein features derived from sequence, structural and functional analyses. Each protein in CaviDB is linked to its corresponding conformers, which also facilitates the study of conformational changes in cavities. Our initial release includes ∼927 773 distinct proteins, as well as the characterization of 36 136 869 cavities, of which 1 147 034 were predicted to be drug targets. The structural focus of CaviDB provides the ability to compare cavities and their properties from different conformational states of the protein. CaviDB not only aims to provide a comprehensive database that can be used for various aspects of drug design and discovery but also contributes to a better understanding of the fundamentals of protein structure-function relationships. With its unique approach, CaviDB represents an indispensable resource for the large community of bioinformaticians in particular and biologists in general. Database URL https://www.cavidb.org.

OBI: A computational tool for the analysis and systematization of the positive selection in proteins.

There are multiple tools for positive selection analysis, including vaccine design and detection of variants of circulating drug-resistant pathogens in population selection. However, applying these tools to analyze a large number of protein families or as part of a comprehensive phylogenomics pipeline could be challenging. Since many standard bioinformatics tools are only available as executables, integrating them into complex Bioinformatics pipelines may not be possible. We have developed OBI, an open-source tool aimed to facilitate positive selection analysis on a large scale. It can be used as a stand-alone command-line app that can be easily installed and used as a Conda package. Some advantages of using OBI are:•It speeds up the analysis by automating the entire process•It allows multiple starting points and customization for the analysis•It allows the retrieval and linkage of structural and evolutive data for a protein throughWe hope to provide with OBI a solution for reliably speeding up large-scale protein evolutionary and structural analysis.

Application of data augmentation techniques towards metabolomics.

Niemann-Pick Class 1 (NPC1) disease is a rare and debilitating neurodegenerative lysosomal storage disease (LSD). Metabolomics datasets of NPC1 patients available to perform this type of analysis are often limited in the number of samples and severely unbalanced. In order to improve the predictive capability and identify new biomarkers in an NPC1 disease urinary dataset, data augmentation (DA) techniques based on computational intelligence have been employed to create synthetic samples, i.e. the addition of noise, oversampling techniques and conditional generative adversarial networks. These techniques have been used to evaluate their predictive capacities on a set of urine samples donated by 13 untreated NPC1 disease and 47 heterozygous (parental) carrier control participants. Results on the prediction have also been obtained using different machine learning classification models and the partial least squares techniques. These results provide strong evidence for the ability of DA techniques to generate good quality synthetic data. Results acquired show increases in sensitivity of 20%-50%, an F1 score of 6%-30%, and a predictive capacity of 0.3 (out of 1). Additionally, more conventional forms of multivariate data analysis have been employed. These have allowed the detection of unusual urinary metabolite profiles, and the identification of biomarkers through the use of synthetically augmented datasets. Results indicate that urinary branched-chain amino acids such as valine, 3-aminoisobutyrate and quinolinate, may be employable as valuable biomarkers for the diagnosis and prognostic monitoring of NPC1 disease.

Integration of a Passive Exoskeleton and a Robotic Supernumerary Finger for Grasping Compensation in Chronic Stroke Patients: The SoftPro Wearable System.

Upper-limb impairments are all-pervasive in Activities of Daily Living (ADLs). As a consequence, people affected by a loss of arm function must endure severe limitations. To compensate for the lack of a functional arm and hand, we developed a wearable system that combines different assistive technologies including sensing, haptics, orthotics and robotics. The result is a device that helps lifting the forearm by means of a passive exoskeleton and improves the grasping ability of the impaired hand by employing a wearable robotic supernumerary finger. A pilot study involving 3 patients, which was conducted to test the capability of the device to assist in performing ADLs, confirmed its usefulness and serves as a first step in the investigation of novel paradigms for robotic assistance.

Treg and TH17 link to immune response in individuals with peri-implantitis: a preliminary report.

BACKGROUND AND OBJECTIVES: Treg and TH17 cells influence the inflammatory process in periodontal diseases and could also play in a similar pattern, an essential role in immune-inflammatory mechanisms involved in the destruction of the peri-implant tissues, peri-implantitis. Therefore, this study evaluated the levels of RORγT and FOXP3 gene expression in subjects with peri-implantitis and healthy peri-implant tissues. METHODS: A total of 35 subjects with implant-supported restorations in both diseased and healthy clinical conditions (n = 15 healthy; n = 20 peri-implantitis) were included in this study. Peri-implantitis was defined as probing depth > 5 mm, bleeding on probing and/or suppuration, and peri-implant bone loss >4 mm. Peri-implant tissue biopsies were collected for analysis of the mRNA, RORγT, and FOXP3 expression levels. The samples were submitted to total RNA extraction, treatment with DNAse, and cDNA synthesis. Subsequently, real-time PCR reaction was performed to evaluate the levels of RORγT and FOXP3 gene expression to the reference gene. These were analyzed by the non-parametric Mann-Whitney method with a level of significance of 5%. RESULTS: Higher gene expression levels of the transcription factors RORγT and FOXP3 were detected in the tissues affected by peri-implantitis when compared with healthy tissues (p < 0.05). CONCLUSIONS: The present study demonstrated the possible existence of a hybrid TH17-Treg profile, based on the gene expression of transcription factors inducing differentiation of these cells. Further studies must be designed to gain a better understanding of the immunological mechanisms involved in the pathogenesis of peri-implantitis. CLINICAL RELEVANCE: The levels of RORγT and FOXP3 transcription factors that were linked to cells with the FOXP3+RORγT+ phenotype could be used as a predictor of peri-implantitis progression.

Transfer learning with convolutional neural networks for cancer survival prediction using gene-expression data.

Precision medicine in oncology aims at obtaining data from heterogeneous sources to have a precise estimation of a given patient's state and prognosis. With the purpose of advancing to personalized medicine framework, accurate diagnoses allow prescription of more effective treatments adapted to the specificities of each individual case. In the last years, next-generation sequencing has impelled cancer research by providing physicians with an overwhelming amount of gene-expression data from RNA-seq high-throughput platforms. In this scenario, data mining and machine learning techniques have widely contribute to gene-expression data analysis by supplying computational models to supporting decision-making on real-world data. Nevertheless, existing public gene-expression databases are characterized by the unfavorable imbalance between the huge number of genes (in the order of tenths of thousands) and the small number of samples (in the order of a few hundreds) available. Despite diverse feature selection and extraction strategies have been traditionally applied to surpass derived over-fitting issues, the efficacy of standard machine learning pipelines is far from being satisfactory for the prediction of relevant clinical outcomes like follow-up end-points or patient's survival. Using the public Pan-Cancer dataset, in this study we pre-train convolutional neural network architectures for survival prediction on a subset composed of thousands of gene-expression samples from thirty-one tumor types. The resulting architectures are subsequently fine-tuned to predict lung cancer progression-free interval. The application of convolutional networks to gene-expression data has many limitations, derived from the unstructured nature of these data. In this work we propose a methodology to rearrange RNA-seq data by transforming RNA-seq samples into gene-expression images, from which convolutional networks can extract high-level features. As an additional objective, we investigate whether leveraging the information extracted from other tumor-type samples contributes to the extraction of high-level features that improve lung cancer progression prediction, compared to other machine learning approaches.

Strontium ranelate improves alveolar bone healing in estrogen-deficient rats.

BACKGROUND: This study evaluated the impact of strontium ranelate on tooth-extraction wound healing in estrogen-deficient and estrogen-sufficient rats. METHODS: Ninety-six Wistar rats (90 days of age) were allocated into one of the following groups: sham-surgery+water (estrogen-sufficient); ovariectomy+water (estrogen-deficient), sham-surgery+strontium ranelate (625 mg/kg/d) (strontium/estrogen-sufficient); ovariectomy+strontium ranelate (625 mg/kg/d) (strontium/estrogen-deficient). Water or strontium ranelate were administrated from the 14th day post-ovariectomy/sham surgery until euthanasia. Maxillary first molars were extracted at 21 days after sham/ovariectomy surgery. Rats were euthanized at 10, 20, and 30 days post-extractions. The following parameters were analyzed inside tooth-extraction wound: proportion of newly formed bone (bone healing/BH), number of cells stained for tartrate-resistant acid phosphatase (TRAP) and immunohistochemical staining for five bone metabolism-related markers (osteocalcin [OCN], osteopontin [OPN], bone sialoprotein [BSP], osteoprotegerin [OPG] and receptor activator of NF-КB ligand [RANKL]). RESULTS: The estrogen-deficient group presented lower BH than all other groups at 20 and 30 days post-extraction (P < 0.05). The number of TRAP-stained cells was higher in the estrogen-deficient group than in estrogen-sufficient group at 30 days post-extraction (P < 0.05). The strontium /estrogen-sufficient group exhibited stronger staining for OCN, when compared to the estrogen-sufficient and estrogen-deficient groups (P < 0.05). Both strontium ranelate-treated groups presented higher staining of OPN and BSP than both untreated groups (P < 0.05). The strontium/estrogen-sufficient group demonstrated stronger staining for OPG than the estrogen-deficient group (P < 0.05). The estrogen-sufficient group and both groups treated with strontium ranelate showed lower expression of RANKL than the estrogen-deficient group (P < 0.05). CONCLUSIONS: Strontium ranelate benefited BH and the expression of bone markers in tooth-extraction wound in estrogen-deficient rats whereas its benefits in estrogen-sufficient rats were modest.

BLASSO: integration of biological knowledge into a regularized linear model.

BACKGROUND: In RNA-Seq gene expression analysis, a genetic signature or biomarker is defined as a subset of genes that is probably involved in a given complex human trait and usually provide predictive capabilities for that trait. The discovery of new genetic signatures is challenging, as it entails the analysis of complex-nature information encoded at gene level. Moreover, biomarkers selection becomes unstable, since high correlation among the thousands of genes included in each sample usually exists, thus obtaining very low overlapping rates between the genetic signatures proposed by different authors. In this sense, this paper proposes BLASSO, a simple and highly interpretable linear model with l1-regularization that incorporates prior biological knowledge to the prediction of breast cancer outcomes. Two different approaches to integrate biological knowledge in BLASSO, Gene-specific and Gene-disease, are proposed to test their predictive performance and biomarker stability on a public RNA-Seq gene expression dataset for breast cancer. The relevance of the genetic signature for the model is inspected by a functional analysis. RESULTS: BLASSO has been compared with a baseline LASSO model. Using 10-fold cross-validation with 100 repetitions for models' assessment, average AUC values of 0.7 and 0.69 were obtained for the Gene-specific and the Gene-disease approaches, respectively. These efficacy rates outperform the average AUC of 0.65 obtained with the LASSO. With respect to the stability of the genetic signatures found, BLASSO outperformed the baseline model in terms of the robustness index (RI). The Gene-specific approach gave RI of 0.15±0.03, compared to RI of 0.09±0.03 given by LASSO, thus being 66% times more robust. The functional analysis performed to the genetic signature obtained with the Gene-disease approach showed a significant presence of genes related with cancer, as well as one gene (IFNK) and one pseudogene (PCNAP1) which a priori had not been described to be related with cancer. CONCLUSIONS: BLASSO has been shown as a good choice both in terms of predictive efficacy and biomarker stability, when compared to other similar approaches. Further functional analyses of the genetic signatures obtained with BLASSO has not only revealed genes with important roles in cancer, but also genes that should play an unknown or collateral role in the studied disease.

Expression Levels of Semaphorins 3A, 3B, 4A, and 4D on Human Peri-implantitis.

PURPOSE: To evaluate the gene expression levels of semaphorins 3A, 3B, 4A, and 4D in both healthy and diseased implants. MATERIALS AND METHODS: Subjects with peri-implantitis presented clinical attachment loss, probing depth ≥ 5 mm, bleeding on probing and/or suppuration, and radiographic bone loss > 4 mm. Peri-implant tissue biopsy specimens were sampled for analysis of the mRNA expression levels for semaphorins 3A, 3B, 4A, and 4D. A real-time polymerase chain reaction was performed, and the gene expression levels of semaphorins in relation to the housekeeping gene were analyzed by using the nonparametric Mann-Whitney test (P < .05). RESULTS: Thirty-five subjects (16 men, 19 women; mean age: 54.12 ± 2.34 years) with implant-supported restorations, using screw-shaped dental implants with internal or external hexagon were enrolled in this study. Higher levels of semaphorins 3A and 4D were detected in the peri-implantitis compared with the healthy tissues (P = .0011 and P = .0404, respectively), whereas Sem4A levels were significantly higher in the control group (P < .0001). Differences between groups in the expression levels of Sem3B were not significant. CONCLUSION: Advanced peri-implantitis lesions showed higher levels of gene expression for Sem3A and Sem4D and lower levels of Sem4A in comparison to tissues obtained from a healthy dental implant.

Exposição persistente de tela de titânio em enxerto ósseo da maxila anterior: considerações e caso clínico / Persistent exposure of titanium mesh on the anterior bone-grafted maxilla: considerations and case report

A tela de titânio é um recurso importante e amplamente utilizado em diversos tipos de enxertos ósseos. Contudo, apresenta um alto índice de exposição, o que pode comprometer total ou parcialmente o tratamento. Nesse contexto, é importante o profissional compreender diferentes formas de lidar com essa intercorrência, possibilitando o melhor prognóstico possível do enxerto, além de diminuir o desconforto do paciente. O presente trabalho apresenta um caso clínico de enxerto particulado com tela de titânio na região anterior da maxila, com exposição precoce e persistente do enxerto, mesmo frente a diferentes intervenções. O relato descreve as abordagens envolvidas em diferentes momentos da exposição e discute os aspectos teóricos e práticos envolvidos, incluindo a etiologia, os biomateriais utilizados, sua relação com exposições ao meio bucal e as prováveis razões pela quais o enxerto não apresentou perda significante de volume, mesmo após 41 dias exposto ao meio bucal.

Titanium mesh is an important and widely used resource in several types of bone grafts. However, it has a high prevalence of exposure, which may partially or totally compromise the treatment. In this sense, it is important for the professional to understand different ways of dealing with this problem, allowing the best possible prognosis of the graft, besides reducing the discomfort of the patient. The present work presents a case report of particulate graft with titanium mesh in the anterior region of the maxilla, with early and persistent graft exposure, even in front of different interventions. This report describes the approaches involved in different times of exposition and discusses the theoretical and practical aspects involved, including etiology, the biomaterials used, its relation with exposures to the oral environment and the likely reasons why the graft did not present signifi cant loss of volume, even after 41 days exposed to the mouth.

Utilização de PRF líquido como biomaterial auxiliar em enxertos particulados / Use of liquid PRF as auxiliary biomaterial in particulate grafts ­ case report

O PRF líquido pode facilitar o posicionamento e a escultura de enxertos ósseos particulados, além dos possíveis benefícios relacionados ao reparo ósseo e fibromucosa. Para tanto, é necessário que o profissional conheça os aspectos práticos e teóricos envolvidos no seu uso. Um paciente com 45 anos de idade, apresentava perda dos incisivos maxilares e de espessura da crista óssea na região, impossibilitando a colocação de implantes de diâmetro convencional. Para a regeneração óssea, foi utilizado enxerto com substituto ósseo associado a coágulos de PRF, PRF líquido e tela de titânio. Após o reparo ósseo, foram instalados dois implantes na região dos incisivos laterais como pilares de uma prótese parcial fixa de quatro elementos. O PRF líquido pode facilitar procedimentos de enxertia óssea e diminuir o risco de iatrogenia sem, contudo, aumentar significativamente o custo e o tempo do tratamento.

The liquid PRF can facilitate the positioning and carving of particulate bone grafts, in addition to possible benefi ts related to bone and soft tissue repair. Therefore, it is necessary that the professional knows the practical and theoretical aspects involved in its use. A 45-year-old patient presented loss of maxillary incisors and thickness of the bone crest in the region, making it impossible to place implants of conventional diameter. For bone regeneration, graft was used with bone substitute associated with PRF clots, liquid PRF and titanium mesh. After bone repair, two implants were installed in the region of the lateral incisors as pillars of a fixed partial denture of four elements. The liquid PRF can facilitate bone graft procedures and reduce the risk of iatrogenic, without, however, significantly increasing the cost and time of treatment.

Substituição dentária conservadora utilizando implantes e o dente pré-existente para provisórios estéticos / Conservative tooth replacement using implants and pre-existing tooth for aesthetic provisional restorations

Objetivo: apresentar, através de um caso clínico, a utilização de coroas de dentes extraídos como provisórios em próteses fixas unitárias maxilares anteriores, favorecendo aspectos como estética, conforto psicológico, perfil de emergência, biocompatibilidade com tecidos moles e durabilidade em relação a provisórios fixos convencionais. Características do paciente: alta demanda estética, apresentando incisivos centrais maxilares com indicação de substituição por implantes, mas com estética coronária satisfatória. Tratamento propriamente dito: através de desgaste seletivo da coroa original, cobertura do intermediário metálico com resina opaca e preenchimento com resina flow, foi possível a utilização das coroas originais da paciente como provisórios imediatos. Conclusão: a utilização de coroas fixas implantossuportadas construídas a partir de coroas naturais pode melhorar aspectos estéticos, biológicos e psicológicos do tratamento, quando corretamente indicadas e aplicadas.

Objective: to present a case report of the use of extracted teeth as provisional crowns in fixed maxillary prosthesis, favoring aesthetics, psychological comfort, emergency profile, soft tissue biocompatibility and durability in relation to conventional fixed prosthesis. Patient characteristics: patient with high aesthetic demand, presenting maxillary central incisors with indication for replacement with implants, but with satisfactory dental aesthetics. Proposed treatment: through selective wear of the original crown, coating of the metallic abutment with opaque resin and filling with flow resin, it was possible the use of the patient's original crowns as immediate prosthesis. Conclusion: the option to use implantsupported fi xed crowns constructed from natural crowns can help patients with aesthetic, biological and psychological aspects of the treatment, as long as correctly indicated and applied.

Supervised discretization can discover risk groups in cancer survival analysis.

Discretization of continuous variables is a common practice in medical research to identify risk patient groups. This work compares the performance of gold-standard categorization procedures (TNM+A protocol) with that of three supervised discretization methods from Machine Learning (CAIM, ChiM and DTree) in the stratification of patients with breast cancer. The performance for the discretization algorithms was evaluated based on the results obtained after applying standard survival analysis procedures such as Kaplan-Meier curves, Cox regression and predictive modelling. The results show that the application of alternative discretization algorithms could lead the clinicians to get valuable information for the diagnosis and outcome of the disease. Patient data were collected from the Medical Oncology Service of the Hospital Clínico Universitario (Málaga, Spain) considering a follow up period from 1982 to 2008.

Advanced Online Survival Analysis Tool for Predictive Modelling in Clinical Data Science.

One of the prevailing applications of machine learning is the use of predictive modelling in clinical survival analysis. In this work, we present our view of the current situation of computer tools for survival analysis, stressing the need of transferring the latest results in the field of machine learning to biomedical researchers. We propose a web based software for survival analysis called OSA (Online Survival Analysis), which has been developed as an open access and user friendly option to obtain discrete time, predictive survival models at individual level using machine learning techniques, and to perform standard survival analysis. OSA employs an Artificial Neural Network (ANN) based method to produce the predictive survival models. Additionally, the software can easily generate survival and hazard curves with multiple options to personalise the plots, obtain contingency tables from the uploaded data to perform different tests, and fit a Cox regression model from a number of predictor variables. In the Materials and Methods section, we depict the general architecture of the application and introduce the mathematical background of each of the implemented methods. The study concludes with examples of use showing the results obtained with public datasets.

Clinical and systemic effects of periodontally accelerated osteogenic orthodontics: a pilot study / Efectos clínicos y sistémicos de la ortodoncia osteogénica periodontalmente acelerada: un estudio piloto

The aim of this study was to describe periodontal effects and treatment time of Periodontally Accelerated Osteogenic Orthodontics (PAOO) and to determine if Deoxypyridinoline could be used as a biochemical marker of bone turnover in patients undergoing PAOO. We compared 5 patients undergoing PAOO (5 males, mean age: 29.6±9.8 years) with 5 control patients undergoing self-ligating orthodontics (5 males, mean age: 28.5±6.3 years). All patients were evaluated using panoramic and lateral x-rays and CBCT and randomly selected in experimental and control groups. Both groups underwent self-ligating orthodontics using Damon Q braces. Only the experimental group underwent PAOO. The patients were evaluated periodontally at T1 (before surgery and orthodontic movement) and T2 (after orthodontic treatment). The total treatment time for the experimental group was 8.2±3.3 months and for the control group was 13.4±7.3 months. There were no differences between T2-T1 periodontal variables in either of the groups. Gingival recession was 0.49±0.26 mm at T1 and 0.42±0.3 mm at T2 in the experimental group. Gingival recession was 0.55±0.31 mm at T1 and 1.19±0.24 mm at T2 in the control group. Deoxypyridinoline urine levels showed great variance between individuals and between groups. There is a reduction in treatment time for patients undergoing PAOO with DAMON Q braces. There is no difference in the periodontal condition between PAOO and conventional orthodontics.

El objetivo de este estudio fue describir los efectos periodontales y el tiempo de tratamiento de ortodoncia osteogénica periodontalmente acelerada (OOPA) y para determinar si desoxipiridinolina podría ser utilizado como un marcador bioquímico de recambio óseo en pacientes sometidos a OOPA. Se estudiaron 5 pacientes sometidos a OOPA (hombres, edad media de 29,6±9,8 años) y 5 pacientes control sometidos a ortodoncia de autoligado (hombres, edad media de 28,5±6,3 años). Todos los pacientes fueron evaluados utilizando radiografías panorámicas y laterales, tomografía computadorizada de haz cónico, y luego distribuidos aleatoriamente en grupos experimentales y de control. Ambos grupos fueron sometidos a la ortodoncia de autoligado utilizando dispositivos ortodónticos Damon Q. Sólo el grupo experimental fue sometido a OOPA. Los pacientes fueron evaluados periodontalmente en T1 (antes de la cirugía y el movimiento de ortodoncia) y T2 (después de un tratamiento de ortodoncia). El tiempo total de tratamiento para el grupo experimental fue de 8,2±3,3 meses y para el grupo control 13,4±7,3 meses. No hubo diferencias entre las variables periodontales T2-T1 en cualquiera de los grupos. La recesión gingival en el grupo experimental fue de 0,49±0,26 mm en T1 y 0,42±0,3 mm en T2. En el grupo control, la recesión gingival fue 0,55±0,31 mm en T1 y 1,19±0,24 mm en T2. Los niveles de desoxipiridinolina en orina mostraron gran variación entre individuos y entre grupos. Hubo una reducción en el tiempo de tratamiento para los pacientes sometidos OOPA con dispositivos ortodónticos Damon Q. No hubo diferencia en la condición periodontal entre pacientes sometidos a OOPA y ortodoncia convencional.

Uso combinado de rhBMP-2, osso bovino particulado, tela de titânio, L-PRF e incisão a distância para reconstrução óssea maxilar extensa / Combined use of rhBMP-2, particulate bovine bone, titanium mesh, L-PRF and remote flap incision for extensive maxillary bone reconstruction ­ case report

O presente trabalho relatou um tratamento com enxerto ósseo, mas sem osso autógeno, de uma maxila atrófica com necessidade de aumento vertical. Foi utilizada uma combinação de rhBMP-2 (Infuse Bone Graft, Medtronic, Minneapolis, EUA), osso bovino particulado (Lumina Bone ­ Large Grain, Criteria, São Carlos, Brasil), tela de titânio (Ti Mesh-Lock, Intra-Lock, São Paulo, Brasil), fibrina rica em plaquetas leucócitos (L-PRF ­ Intra-Lock, São Paulo, Brasil) e incisão de acesso a distância. Após seis meses, as placas de titânio foram removidas e seis implantes foram instalados para suporte de uma prótese total fixa, confeccionada seis meses após a colocação dos implantes. O controle de um ano após instalação da prótese revelou estabilidade do enxerto e dos implantes, sem condições de anormalidade.

This paper describes a treatment with bone graft, but without autogenous bone, in an atrophic maxilla in need of vertical augmentation. A combination of rhBMP-2 (Infuse Bone Graft, Medtronic, Minneapolis, USA), particulate bovine bone (Lumina Bone ­ Large Grain, Criteria, São Carlos, Brazil), titanium mesh (Ti Mesh-Lock, Intra-Lock, São Paulo, Brazil), leukocyte and platelet-rich fibrin (L-PRF ­ Intra-Lock, São Paulo, Brazil) and access with a remote flap incision were used. A discussion on material selection, its advantages, limitations, costs, and treatment time is also presented.

Risco de perda óssea de implantes cone-morse, hexágono externo e interno em próteses totais fixas na maxila ­ análise por elementos finitos 3D / Risk of bone loss for morse taper, external, and internal hexagon dental implants in complete fixed implant-supported prostheses ­ a 3D finite element analysis

Objetivo: analisar comparativamente o risco de perda óssea peri-implantar em próteses totais fixas na maxila, suportadas por seis implantes paralelos, utilizando conexões do tipo hexágono externo (HE), hexágono interno (HI) e cone-morse (CM) através do método dos elementos finitos 3D. Material e métodos: modelos geométricos de uma maxila e prótese foram construídos e unidos aos modelos de implantes de geometria externa semelhante para representar próteses totais maxilares parafusadas, suportadas por seis implantes paralelos cada uma. Os modelos foram submetidos a cargas mastigatórias axiais e oblíquas. Resultados: o risco de perda óssea na carga oblíqua é muito superior à carga axial; nessa condição, a conexão CM apresentou o menor risco de perda óssea e as conexões HE e HI apresentaram risco semelhante, com risco ligeiramente maior do HI. Conclusão: implantes com conexão CM apresentam menor risco de perda óssea peri-implantar, e implantes com conexão HE e HI apresentam risco similar em próteses totais fixas com implantes paralelos.

Objective: to analyze the risk of peri-implant bone loss in complete fixed, implant-supported prosthesis over six parallel implants using the external hex (EH), internal hex (IH), and morse cone (CM) connections through a 3D finite element method. Material and methods: geometric models of a maxilla and prosthesis were constructed and attached to implant models with similar external geometry to represent maxillary screw-retained dentures supported by six parallel implants each. The models were submitted to axial and oblique masticatory loads. Results: the risk of bone loss under oblique loading is higher than for axial loading; in this condition, the CM connections demonstrated the lowest risk of bone loss, with EH and IH connections showing similar risks, although slightly higher for IH. Conclusion: CM implants present less risk for peri-implant bone loss, and the EH and IH had similar values for complete fixed implant-supported restorations over parallel dental implants.