Enhancing mouthguard longevity: Impact of surface treatment against aging from brushing and disinfectant exposure.

BACKGROUND/AIMS: The study aimed to assess the surface characteristics of sports mouthguards under mechanical stresses during cleaning, either by brushing or immersion in disinfectant solutions. MATERIAL AND METHODS: Ethylene-vinyl acetate samples, 4 mm thick, were randomly assigned to cleaning methods: control (C-no cleaning), brushing with water (B.W), brushing with neutral liquid soap (B.S), brushing with toothpaste (B.T), immersion in distilled water for 10 min (I.W), immersion in 2.25% sodium hypochlorite solution for 10 min (I.SH), and immersion in sodium bicarbonate solution for 5 min (I.SB). All cleaning methods were applied for 28 days. Surface roughness average (Ra) and wettability were measured at baseline for the control group (n = 9), and after cleaning for all the other groups. RESULTS: One-way ANOVA with Tukey tests (5% significance) indicated significant differences among groups (p < .05). The I.SB group had higher surface roughness than B.S and B.T (p < .05). B.W showed the lowest wettability, significantly lower than B.T, I.W, and I.SB (p < .05). I.SB exhibited the highest wettability, significantly different from sodium hypochlorite, neutral liquid soap, brushing with water, and control groups (p < .05). The sodium bicarbonate immersion group (I.SB) demonstrated greater statistical variation, displaying higher susceptibility to aging compared to brushing with neutral liquid soap. CONCLUSION: Cleaning mouthguards with a toothbrush, water, and neutral liquid soap emerged as the most promising method, causing minimal surface changes in the material.

Fracture load of complete-arch implant-supported prostheses reinforced with nylon-silica mesh: An in vitro study.

STATEMENT OF PROBLEM: Complete-arch implant-supported prostheses without a framework have a high risk of failure: a straightforward and inexpensive reinforcement material, such as nylon mesh, could improve their longevity. PURPOSE: The purpose of this in vitro study was to evaluate a nylon-silica mesh compound on the fracture strength of acrylic resin and the fracture load of complete-arch implant-supported prostheses. MATERIAL AND METHODS: Twenty-four complete mandibular arch implant-supported prostheses were divided into 2 groups according to cantilever length (molar and premolar) and subdivided into another 2 subgroups according to the presence or absence of reinforcing mesh. The specimens were submitted to a maximum load-to-fracture test in a universal testing machine, with a 100-N load cell, a 2 mm/min crosshead speed, and a spherical metal tip diameter of 4 mm at different points (molar and premolar). These were submitted to 1-way analysis of variance for repeated measurement and the post hoc Tukey multiple comparison test (α=.05). RESULTS: The mean maximum load ±standard deviation for the molar group was 393.4 ±95.0 N with reinforcement and 305.4 ±76.3 N without reinforcement (P=.02); and for the premolar group was 1083.3 ±283.7 N with reinforcement and 605.3 ±90.5 N without reinforcement (P=.001). CONCLUSIONS: Reinforcement with nylon mesh increased the mean maximum load of implant-supported complete-arch prostheses at both cantilever lengths. The cantilever to the premolar (5 mm) presented the highest maximum load values to fracture.

Silver-Coated Silica Nanoparticles Modified with MPS: Potential Antimicrobial Biomaterials Applied in Glaze and Soft Reliner.

Soft reliner and glaze are materials used over full or partial dental prosthesis to prevent excessive pressure on the supporting tissues. They are also indicated as supportive treatment for dental stomatitis, especially when modified by the addition of medications. The objective of the work was to evaluate the antimicrobial effect of silver-coated silica nanoparticles in a glaze and a soft reliner. The nanoparticles were synthesized, characterized, and tested by minimum inhibitory concentration (MIC) for C. albicans SC5314. Then, the nanoparticles were incorporated to a glaze and a soft reliner, which were called nanocomposites. Then, the nanocomposites were divided into six groups (n = 12): CG: glaze/reliner; CR: reliner; G1: glaze + 1% nanoparticles/reliner; G2: glaze + 2.5% nanoparticles/reliner; R1: reliner + 1%; R2: reliner + 2.5%. The nanocomposites were characterized by a goniometer and by a scanning electron microscope. The antibiofilm test was performed against C. albicans SC5314. According to the MIC results, the non-functionalized nanoparticles reduced fungal growth at 1000 µg/mL and the functionalized nanoparticles at 2000 µg/mL. The functionalized nanoparticle had a superior dispersion being selected for the antibiofilm test. There was a reduction of 64% in CFU/specimen count for the glaze, not statistically significant (p = 0.244). For the soft reliner, there was an increase in CFU/specimen with the presence of nanoparticles, still not statistically significant (p = 0.264). In conclusion, it is necessary to conduct new studies to increase the release of silver, thus improving nanoparticles' antifungal potential.

Effect of Light Emission Through an Optical Fiber Device on the Bond Strength of a Hollow Experimental Intraradicular Post.

PURPOSE: To evaluate the effect of irradiation with an optical-fiber device on the bond strength of hollow and partially opaque intraradicular posts. MATERIALS AND METHODS: An optical-fiber accessory tip was attached to a light-curing unit to emit light through the central hollow of an experimental fiberglass post. The samples were divided into 4 groups (n = 80) according to the protocol (Variolink N [light cured] or Multilink N [dual-curing luting material]) and the light-curing mode (performed conventionally or with the optical fiber): GF: light-curing luting material; GFF: light-curing luting material and optical fiber; GD: dual-curing luting material; GDF: dual-curing luting material and optical fiber. The samples were tested immediately or after aging. Push-out bond strength, failure mode, degree of conversion (DC, assessed at the peak of 1750 cm-1), and stress distribution by finite element analysis were performed. Quantitative data were analyzed using 3-way ANOVA (luting material x light curing x depth) and 2-way ANOVA (aging x luting material), followed by Tukey's test. RESULTS: Bond strength was significantly affected by the luting material protocol (p < 0.001), depth (p = 0.010), and light curing mode (p = 0.031). The GFF group revealed higher bond strength in the middle and apical portions. The most frequent failure modes were adhesive in the apical portion for the GFF and GDF groups. The DC was higher for GF and GFF groups. CONCLUSION: Using the optical-fiber device led to superior bond strength results when a dual-curing luting material was used.

Modified impression technique for extreme mouth-opening limitation caused by systemic scleroderma.

Systemic scleroderma is a relatively rare, autoimmune, chronic, and debilitating disease, and its etiology is unknown. The disease is characterized by vasomotor disturbances causing skin and mucosa hardening, hand stiffness, excess production of collagen fibers, and impairment of the internal organs associated with the immune system. Extreme mouth-opening limitation is one of the symptoms in the oral cavity, and compromises dental intervention. One of the fundamental steps when performing a dental procedure is dental arch impression. In the presented clinical case, limited mouth opening hindered the impression accuracy. The objective was to present an alternative impression technique for a patient affected by scleroderma, with limited mouth opening and the need for oral rehabilitation with a removable partial prosthesis in the maxillary arch. An individualized tray was developed with design characteristics that allowed access to the oral cavity and removal, after which it was possible to perform the oral impression, reproducing the areas of interest without causing injury to the oral tissues. The orientation plan was elaborated after obtaining the cast. The teeth were assembled, tested in the mouth, and sent to the laboratory for acrylization. The prosthesis was placed once ready. The alternative impression technique enabled oral rehabilitation of the patient despite the mouth-opening limitation, and provided an accurate impression and a good prosthetic result.

Analysis of bond strength between a nylon reinforcement structure and dental resins.

BACKGROUND: Nylon is a polymer that its use to reinforce dental resins has shown positive results such as increased flexural strength. The aim of this study was to evaluate the bond strength between dental resins and a nylon reinforcement. MATERIAL AND METHODS: Forty cylindrical nylon blocks with 13 x 23 mm with 0.5% by volume of silica and 40 without were made. Half of the samples of each nylon composition were sandblasted with aluminum oxide (50µm) for 3 s (2.8 bar pressure, distance: 20 mm, incidence angle: 90o). On the nylon blocks, cylinders of chemically activated acrylic resin and indirect composite resin were made, with a bonding area of 6,28 mm2. Eight different groups were obtained according to the material used and the surface treatment (n = 10): Acrylic Resin + Nylon; GAS: Acrylic Resin + Nylon with Silica; GAT: Acrylic Resin + Nylon (Al2O3); GAST: Acrylic Resin + Nylon with Silica (Al2O3); GC: Composite Resin + Nylon; GCS: Composite Resin + Nylon with Silica; GCT: Composite Resin + Nylon (Al2O3); GCST: Composite Resin + Nylon with Silica (Al2O3). The shear test was carried out. The Student's and the Kruskal-Wallis test was adopted. RESULTS: There was no statistically difference in the bond strength for nylon with silica for the acrylic resin group. For the composite groups, nylon with silica did not present a statistically difference without surface treatment (p = 0.10) and with surface treatment the bond strength decreased (p = 0.000). The GCT showed a higher bond strength (0.89 MPa). The surface treatment improved the bond strength for the both groups. CONCLUSIONS: The presence of silica in the nylon composition did not influence the bond strength between materials evaluated. However, the surface treatment with aluminum oxide proved to be favorable for this adhesion. Key words:Nylons - Resins, Synthetic - Structures Strengthening - Dental Research.

Evaluation of a new intraoral paralleling device for creating guiding planes: a pilot study.

AIM: The aim of the study was to assess the accuracy of a new intraoral paralleling device for creating proximal guiding planes for removable partial dental prostheses. METHODS AND MATERIALS: Thirty gypsum casts were divided into two groups in which the proximal surfaces of selected teeth were prepared using either a surveying device (Group 1) or the new ParalAB paralleling device (Group 2). In each cast guiding planes were prepared on the distal surface of the maxillary left canine (A), on the mesial and distal surfaces of the maxillary left second molar (B and C), and on the distal surface of the maxillary right canine (D). Each prepared surface formed an angle related to the occlusal plane that was measured five times and averaged by one operator using a tridimensional coordinate machine. RESULTS: The mean guiding plane angles (+/- standard deviation) for the prepared surfaces were A=91.82 degrees (+/-0.48 degrees ), B=90.47 degrees (+/-0.47 degrees ), C=90.21 degrees (+/-0.76 degrees ), and D=90.50 degrees (+/-0.73 degrees ) for the dental surveyor (Group 1) and A=92.18 degrees (+/-0.87 degrees ), B=90.90 degrees (+/-0.85 degrees ), C=90.07 degrees (+/-0.92 degrees ), and D=90.66 degrees (+/-0.76 degrees ) for the ParalAB paralleling device (Group 2). A two-way ANOVA, Tukey's, and Levène's tests (at p<0.05) revealed statistically significant differences among surfaces prepared by both groups and that one surface (A in Group 2) was more parallel to the path of insertion than the other surfaces. CONCLUSIONS: The ParalAB device was able to prepare parallel surfaces and despite significant difference between groups, the ParalAB presented a small deviation from absolute parallelism and can be considered a valid method to transfer guide plans in the fabrication of removable partial dentures. CLINICAL SIGNIFICANCE: The preparation of suitable guiding planes on abutment teeth during the fabrication of removable partial dentures is dependent on the ability of the operator and requires considerable chair time. When multiple teeth are involved, achieving parallelism between abutment surfaces can be technically challenging, especially in posterior regions of the mouth. The ParalAB prototype intraoral paralleling device can aid the clinician during the preparation of accurate guiding planes with a minimum degree of occlusal divergence.

Mouthguard Use Effect on the Biomechanical Response of an Ankylosed Maxillary Central Incisor during a Traumatic Impact: A 3-Dimensional Finite Element Analysis.

(1) Background: Trauma is a very common experience in contact sports; however, there is an absence of data regarding the effect of athletes wearing mouthguards (MG) associated with ankylosed maxillary central incisor during a traumatic impact. (2) Methods: To evaluate the stress distribution in the bone and teeth in this situation, models of maxillary central incisor were created containing cortical bone, trabecular bone, soft tissue, root dentin, enamel, periodontal ligament, and antagonist teeth were modeled. One model received a MG with 4-mm thickness. Both models were subdivided into finite elements. The frictionless contacts were used and a nonlinear dynamic impact analysis was performed in which a rigid object hit the model at 1 m·s-1. For each model, an ankylosed periodontal ligament was simulated totaling 4 different situations. The results were presented in von-Mises stress maps. (3) Results: A higher stress concentration in teeth and bone was observed for the model without a MG and with ankylosed tooth (19.5 and 37.3 MPa, respectively); the most promising mechanical response was calculated for patients with healthy periodontal ligament and MG in position (1.8 and 7.8 MPa, respectively). (4) Conclusions: The MG's use is beneficial for healthy and ankylosed teeth, since it acts by dampening the generated stresses in bone, dentin, enamel and periodontal ligament. However, patients with ankylosed tooth are more prone to root fracture even when the MG is in position compared to a healthy tooth.

Development of a cell phone application as an auxiliary teaching tool for the subject of complete dentures / Desenvolvimento de aplicativo de celular intitulado: "Manual de Prótese Total ­ Reabilitando sorrisos", como uma ferramenta didática auxiliar para a disciplina de prótese total

Objective: The study aimed to develop a cell phone application entitled: "Total Prosthesis Manual ­ Rehabilitating smiles", as an auxiliary teaching tool for teachers and students through digital technology, with a smartphone. Material and Methods: The tool was structured on the "Application Factory website", which allows the creation of mobile applications in different formats, with broad and interactive features on IOS and Android platforms. The expository format of the content is in slide format, containing descriptive theory and images about the stages of making a complete prosthesis; from necessary materials, photos and descriptive guidance of the steps. Results: The application is a complementary teaching resource to assist undergraduate and postgraduate students and professionals working in the area of complete prosthetics. The theoretical and practical content selected for the application covered all stages of understanding, development and possible complications associated with the manufacture of a complete bimaxillary prosthesis, from planning, impressions, models, orientation plans, tooth assembly, adaptations and delivery. Conclusion: The application provided a low-cost, expandable and easy-to-use teaching resource for teaching complete dentures. It is essential to develop various analyzes such as user experience tests, application effectiveness, development of new technologies and improvement of techniques, so that their potential for enriching learning in complete dentures and dentistry in general can be verified.(AU)

Objetivo: O estudo teve como objetivo desenvolver um aplicativo de celular intitulado: "Manual de Prótese Total ­ Reabilitando sorrisos", como uma ferramenta didática auxiliar para professores e alunos por meio da tecnologia digital, com smartphone. Material e Métodos: A ferramenta foi estruturada no "site da Fábrica de Aplicativos", que permite a criação de aplicativos móveis em diversos formatos, com recursos amplos e interativos nas plataformas IOS e Android. A modalidade expositiva do conteúdo é em formato de slides, contendo teoria descritiva e imagens sobre as etapas de confecção de uma prótese total; a partir de materiais necessários, fotos e orientação descritiva das etapas. Resultados: O aplicativo é um recurso didático complementar para auxiliar estudantes de graduação, pós-graduação e profissionais que atuam na área de prótese total. O conteúdo teórico e prático selecionado para a aplicação visou todas as etapas de compreensão, desenvolvimento e possíveis complicações associadas à confecção de uma prótese total bimaxilar, desde o planejamento, moldagens, maquetes, planos de orientação, montagem dos dentes, adaptações e entrega. Conclusão: O aplicativo trouxe um recurso didático de baixo custo, expansível e fácil de usar para o ensino de próteses totais. É fundamental desenvolver diversas análises como testes de experiência do usuário, eficácia de aplicação, desenvolvimento de novas tecnologias e aprimoramento de técnicas, de forma que possa ser verificado seu potencial de enriquecimento do aprendizado em prótese total e odontologia em geral(AU)

Effect of silver-coated silica nanoparticles on the thermal conductivity of thermally activated acrylic resin / Efeito das nanopartículas de sílica revestidas por prata na condutividade térmica da resina acrílica ativada termicamente

Objective: Thermally activated acrylic resins (RAATs) are widely used in dentures as a base material due to their good dimensional stability and biocompatibility. However, their low thermal conductivity is a disadvantage, as it affects acceptance when using dental prostheses. Thus, the objective of this work was to measure the conduction heat in RAATs with and without incorporation of silica and silver nanoparticles (NP) and rigid reline (RR). Material and Methods: For this, samples were made and divided into 10 groups (n = 6). The first five groups were 2-mm-thick samples: G1 (RAAT control), G2 (RAAT + RR control), G3 (RAAT and NP + RR), G4 (RAAT + RR and NP), and G5 (RAAT and RR modified by NP). In the other five groups, 8-mm-thick samples were made: G6 (RAAT control), G7 (RAAT + RR control), G8 (RAAT and NP + RR), G9 (RAAT + RR and NP), and G10 (RAAT and RR modified by NP). The heat that cross the surface of the specimens was quantified using a wireless device. The data were submitted to two-factor ANOVA statistical analysis and Tukey ́s test with a 5% significance level. Results: After measuring the temperature variation as a function of time, it can be observed that there was a statistically significant difference for thermal conduction between the control groups and those modified with NP. Conclusion: Thus, it was possible to conclude that the NP improved the heat conduction in RAAT and in the RR because the nanoparticles have a higher thermal conductivity. (AU)

Objetivo: As resinas acrílicas termicamente ativadas (RAATs) são amplamente utilizada em próteses dentárias como material de base, pois possuem uma boa estabilidade dimensional e biocompatibilidade. Porém, como desvantagem, possuem baixa condutividade térmica, o que prejudica a aceitação do uso de próteses dentárias. Assim, o objetivo deste trabalho foi medir a condução de calor em RAAT com e sem incorporação de nanopartículas de sílica e prata (NP) e reembasador rígido (RR). Material e Métodos: Para isso, foram confeccionadas amostras que foram divididas em 10 grupos (n=6). Os primeiros cinco grupos eram amostras de 2 mm de espessura: G1 (RAAT controle), G2 (RAAT + RR controle), G3 (RAAT e NP + RR), G4 (RAAT + RR e NP) e G5 (RAAT e RR modificados por NP). E nos outros cinco grupos foram feitas amostras com espessura de 8 mm: G6 (RAAT controle), G7 (RAAT + RR controle), G8 (RAAT e NP + RR), G9 (RAAT + RR e NP) e G10 (RAAT e RR modificados por NP). O calor percorrido pela superfície dos corpos ­ de prova foi quantificado por meio de um dispositivo sem fio. Os dados foram submetidos à análise estatística ANOVA dois fatores e teste de Tukey com 5% de significância. Resultados: Após medir a variação da temperatura em função do tempo, pode-se observar que houve diferença estatisticamente significante para a condução térmica entre os grupos controle e os modificados com NP. Conclusão: Assim, foi possível concluir que a NP melhorou a condução de calor na RAAT e no RR, pois as nanopartículas apresentam maior condutividade térmica. (AU)

Influence of fibromucosa height and loading on the stress distribution of a total prosthesis: a finite element analysis / Influência da altura da fibromucosa e carregamento na distribuição de tensões de prótese total: análise por elementos finitos

Purpose: To evaluate the effect of fibromucosa height on the stress distribution and displacement of mandibular total prostheses during posterior unilateral load, posterior bilateral load and anterior guidance using the finite element analysis (FEA). Material and methods: 3D virtual models were made to simulate the stress generated during different mandibular movements in a total prosthesis. The contacts were simulated according to the physiology, being considered perfectly bonded between cortical and medullar bones; and between cortical bone and mucosa. Non-linear frictional contact was used for the total prosthesis base and fibromucosa, allowing the prosthesis to slide over the tissue. The cortical bone base was fixed and the 100 N load was applied as unilateral load, posterior bilateral load and anterior guidance simulation. The required results were for maximum principal stress (MPa), microstrain (mm/mm) and total displacement (mm). The numerical results were converted into colorimetric maps and arranged according to corresponding scales. Results: The stress generated in all situations was directly proportional to the fibromucosa height. The maximum principal stress results demonstrated greater magnitude for anterior guidance, posterior unilateral and posterior bilateral, respectively. Only posterior unilateral load demonstrated an increase in bone microstrain, regardless of the fibromucosa height. Prosthesis displacement was lower under posterior bilateral loading. Conclusion: Posterior bilateral loading is indicated for total prosthesis because it allows lower prosthesis displacement, lower stress concentration at the base of the prosthesis and less bone microstrain. (AU)

Objetivo: Avaliar o efeito da altura da fibromucosa na distribuição de tensões e deslocamento das próteses totais mandibulares durante a carga unilateral posterior, carga bilateral posterior e orientação anterior usando a análise por elementos finitos (FEA). Material e métodos: Modelos virtuais 3D foram confeccionados para simular a tensão gerada durante diferentes movimentos mandibulares em uma prótese total. Os contatos foram simulados de acordo com a fisiologia, sendo considerados perfeitamente unidos entre os ossos corticais e medulares; e entre o osso cortical e a mucosa. O contato friccional não linear foi utilizado entre a base total da prótese e a fibromucosa, permitindo que a prótese deslizasse sobre o tecido. A base do osso cortical foi fixada e a carga de 100 N aplicada como carga unilateral, carga bilateral posterior e simulação de guia incisiva anterior. Os resultados foram calculados em tensão máxima principal (MPa), microdeformação (mm/mm) e deslocamento total (mm). Os resultados numéricos foram convertidos em mapas colorimétricos e organizados de acordo com as escalas correspondentes. Resultados: A tensão gerada em todas as situações foi diretamente proporcional à altura da fibromucosa. Os resultados de tensão máxima principal demonstraram maior magnitude durante a carga anterior, posterior unilateral e posterior bilateral, respectivamente. Apenas a carga unilateral posterior demonstrou aumento da microdeformação óssea, independente da altura da fibromucosa. O deslocamento da prótese foi menor sob carga bilateral posterior. Conclusão: A carga bilateral posterior é indicada para prótese total, pois permite menor deslocamento da prótese, menor concentração de tensões na base da prótese e menor microdeformação óssea (AU)

Full digital workflow in fixed adhesive dental prosthesis: Description of a clinical technique / Fluxo de trabalho digital completo em prótese fixa adesiva: descrição de uma técnica clínica

Digital dentistry has gained space in several dental specialties. It is possible to achieve excellent results with the digital workflow, which combines the efficiency of the restorative material with a greater marginal adaptation. This study aimed to report a clinical case through the digital workflow, with a faster and clinically acceptable prosthetic resolution. In this clinical case report, digital workflow allowed a faster and clinically acceptable prosthetic resolution. A 45-year-old female patient reported cementation failure of the prosthetic crown on tooth 14. As it was a vital tooth, the tooth received a total crown preparation. In the same clinical session, the patient's mouth was scanned then a capture software obtained a virtual model. After, the design software planned a digital "diagnostic wax-up", so a leucitic ceramic was chosen for the rehabilitation. The ceramic block was milled and receive stain and glaze, dispensing the prosthesis laboratory. Then, the adhesive cementation was performed with a dual-polymerized resin cement. The final crown had ideal adaptation, with no need for interproximal and occlusal adjustments, with an excellent marginal fit. Within the limitations of this study, this case report showed that the digital workflow allowed a favorable result in a shorter working time, which brought back function and aesthetics, without the need for interproximal and occlusal adjustments. (AU)

A odontologia digital vem ganhando espaço em diversas especialidades odontológicas. Com o fluxo de trabalho digital, é possível alcançar excelentes resultados na reabilitação protética, combinando a eficiência do material restaurador com a adaptação marginal proporcionada pela odontologia digital. O objetivo desse estudo foi relatar um caso clínico através do fluxo de trabalho digital, com uma resolução protética mais rápida e clinicamente aceitável. Paciente do sexo feminino, 45 anos, relatou falha de cimentação da coroa protética do dente 26. Por ser um dente vital, o dente recebeu um preparo de coroa total e os dentes foram escaneados e um software de captura obteve um modelo virtual. Posteriormente, o software de projeto planejou um "enceramento diagnóstico" digital, sendo escolhida uma cerâmica leucítica para a reabilitação. O bloco cerâmico foi fresado e recebeu acabamento, maquiagem e glaze pelo próprio dentista, dispensando um técnico laboratorial de prótese dentária. Em seguida, foi realizada cimentação adesiva definitiva. Este relato de caso mostra que, dentro das limitações desse estudo, o fluxo digital permite um resultado favorável em um menor tempo de trabalho, devolvendo a função e estética, sem necessidade de ajustes interproximais e oclusais (AU)

Overdenture on dental remaining in oncological patients: case report / Overdenture sobre remanescente dental em paciente oncológico: relato de caso

Head and neck cancer occupy the seventh place among the most common neoplasms in the world, with an annual incidence of approximately 640,000 new cases. Radiotherapy treatment has been highlighted, because there is greater tissue preservation, possibility of regression of the disease, decreased tumor volume, prevention of possible tumor recurrences and metastases, and even total cancer cure, but patients undergoing radiotherapy are at high risk of osteoradionecrosis if they perform surgical interventions in the region, such as dental implants and dental extraction, making prosthetic rehabilitation of partially edentulous patients after treating oral cancer something complex and often omitted; although it is a crucial factor in restoring oral function. Thus, the aim of the present study was to describe the planning, treatment and follow-up of a twelve-month prosthetic approach to rehabilitate the lower arch shape and function of a partially edentulous patient undergoing head and neck radiotherapy with a full denture mucus supported and tooth retained. After twelve months of follow-up, it was possible to evidence the functional and aesthetic clinical success, with preserved occlusal pattern, soft and bone tissue around and dental roots. (AU)

O câncer de cabeça e pescoço ocupa o sétimo lugar entre as neoplasias mais comuns do mundo, com uma incidência anual de aproximadamente 640.000 novos casos. O tratamento com radioterapia tem se destacado, pois há maior preservação tecidual, possibilidade de regressão da doença, diminuição do volume tumoral, prevenção de possíveis recorrências e metástases tumorais e até cura total do câncer, mas os pacientes submetidos à radioterapia apresentam alto risco de osteorradionecrose se realizar intervenções cirúrgicas na região, como implantes dentários e extração dentária, fazendo com que a reabilitação protética, de pacientes parcialmente dentados depois de tratar o câncer bucal, algo complexo e frequentemente omitido; embora seja um fator crucial para o reestabelecimento da função oral. Assim, o objetivo do presente estudo foi descrever o planejamento, tratamento e acompanhamento de doze meses de uma abordagem protética para reabilitar forma e função do arco inferior de um paciente parcialmente desdentado, submetido a radioterapia de cabeça e pescoço, com o uso de uma prótese total mucossuportada e dente retida. Após doze meses de acompanhamento, foi possível evidenciar o sucesso clínico funcional e estético, com padrão oclusal, rebordo alveolar e remanescentes dentários preservados (AU)

Influence of surface treatments in flexural strength and superficial topography of a lithium disilicate ceramic / Influência dos tratamentos de superfície na resistência à flexão e na topografia superficial de uma cerâmica de dissilicato de lítio

Objective: The aim of the study was to evaluate the influence of different surface post-etching treatments in flexural strength, contact angle and surface roughness of a lithium disilicate ceramic. Material and Methods: 60 bars (16 x 2 x 4 mm) were divided in six groups (n=10): C, no treatment; HF, hydrofluoric acid for 20 s (HF) + washing (60 s), drying (30s); HFL, HF + washing (60 s), drying (30 s) and luting; HFNL, HF + washing (60 s) + neutralization with sodium bicarbonate (SB) for 40 s + washing (5s), drying (30 s) and luting; HFUL, HF + washing (60 s) + ultrasonic bath (UB) for 4 min, drying (30 s) and luting; HFNUL, HF + washing (60 s) + SB (40 s) + UB (4 min) and luting. The bars were submitted to three-points flexural strength test. 25 ceramic blocks (12 x 7 x 7 mm) were divided into five groups (n=5) to evaluate roughness and contact angle C - no treatment; HF - HF ; HFU - HF and UB for 5 min ; HFN - HF and SB; HFNU - HF, UB and SB. A scanning electron microscope (SEM) showed the surface of the samples. ANOVA one-way statistical analysis was done for comparison of results. Results: There was no statistical difference for flexural strength (p-value = 0.15) and for surface roughness (p-valor = 0.15). However, it was obtained statistically significant difference for contact angle (p-valor = 0.00). SEM images showed precipitates after the acid etching, which were removed by post-etching treatments. Conclusion: It can be concluded that the different post-etching surface treatments did not increase the flexural strength, surface roughness, but it influenced the ceramic wetting and SEM images (AU)

Objetivo: O objetivo do estudo foi avaliar a influência de diferentes tratamentos pós-condicionamento na resistência à flexão, ângulo de contato e rugosidade superficial de uma cerâmica de dissilicato de lítio. Material e Métodos: 60 barras (16 x 2 x 4 mm) foram divididas em seis grupos (n = 10): C, sem tratamento; HF, ácido fluorídrico durante 20 s (HF) + lavagem (60 s), secagem (30 s); HFL, lavagem com HF + (60 s), secagem (30 s) e cimentação; HFNL, HF + lavagem (60 s) + neutralização com bicarbonato de sódio (SB) por 40 s + lavagem (5s), secagem (30 s) e cimentação; HFUL, HF + lavagem (60 s) + banho ultrassônico (UB) por 4 min, secagem (30 s) e cimentação; HFNUL, HF + lavagem (60 s) + SB (40 s) + UB (4 min) e cimentação. As barras foram submetidas ao teste de resistência à flexão de três pontos. 25 blocos cerâmicos (12 x 7 x 7 mm) foram divididos em cinco grupos (n = 5) para avaliação da rugosidade superficial e ângulo de contato C - sem tratamento; HF - HF; HFU - HF e UB por 5 min; HFN - HF e SB; HFNU - HF, UB e SB. Um microscópio eletrônico de varredura (MEV) foi utilizado para análise da superfície das amostras. A análise estatística unidirecional ANOVA-um fator foi realizada para comparação dos resultados. Resultados: Não houve diferença estatística para a resistência à flexão (p-valor = 0,15) e para a rugosidade superficial (p-valor = 0,15). No entanto, obteve-se diferença estatisticamente significante para o ângulo de contato (p-valor = 0,00). Imagens de microscopia eletrônica de varredura mostraram a formação de precipitados após o ataque ácido, que foram removidos pelos tratamentos pós-condicionamento. Conclusão: Pode-se concluir que os diferentes tratamentos de superfície pós-condicionamento não aumentaram a resistência à flexão, rugosidade da superfície, mas influenciaram na molhabilidade da cerâmica e nas imagens em MEV.(AU)

The influence of disinfection on dimensional stability of temporary crowns / A influência da desinfecção na estabilidade dimensional de coroas temporárias

Objective: Evaluate the influence of different disinfection methods on the dimensional stability of temporary acrylic resin crowns. Material and Methods: A metallic die with two different marks at the margin was used to prepare the specimens with two different resins (bis-acrylic resin-Structur, acrylic resin-Dencrilay). They were divided into eight groups (n=8), determined according to the disinfection methods (microwave, acetic acid, 1% hypochlorite) and control. The marginal adaptation was recorded using an optical microscope (50X) comparing two different marks on the margin of the crowns with 2 points along the entire circumferential margin before and after disinfection methods. Results: Results were compared statistically by ANOVA and Tukey's test (p≤0.05). The two-way ANOVA showed statistical difference between types of materials. No significant differences were found between disinfection methods and interaction of factors. Conclusion: All procedures affected the marginal adaptation however temporary crowns made by bis-acrylic resin demonstrate higher dimensional stability. (AU)

Objetivo: Avaliar a influência de diferentes métodos de desinfecção na estabilidade dimensional de coroas temporárias de resina acrílica. Material e Métodos: um molde metálico com duas marcas diferentes na margem foi utilizado para preparar os espécimes com duas resinas diferentes (resina bis-acrílica - estrutura, resina acrílica-Dencrilay). Eles foram divididos em oito grupos (n = 8), determinados de acordo com os métodos de desinfecção (microondas, ácido acético, 1% de hipoclorito) e controle. A adaptação marginal foi registrada usando um microscópio óptico (50X) comparando duas marcas diferentes na margem das coroas com 2 pontos ao longo de toda a margem circunferencial antes e após os métodos de desinfecção. Resultados: os resultados foram comparados estatisticamente por ANOVA e teste de Tukey (p≤0,05). A ANOVA de dois fatores mostrou diferença estatística entre os materiais utilizados. Não foram encontradas diferenças significativas entre os métodos de desinfecção e a interação dos fatores. Conclusão: Todos os procedimentos afetaram a adaptação marginal, porém as coroas temporárias feitas em resina bis-acrílica demonstram maior estabilidade dimensional. (AU)

Electromyographic activity in patient with an inferior implant/tooth-supported overdenture: clinical report / Atividade eletromiográfica de um paciente com prótese inferior implantodentossuportada: Relato de caso clínico

Clinicians can find patients with one mandibular remaining tooth, and it is difficult to decide if the tooth has to be removed. When a clinician decides to maintain the tooth, it is common to question the masticatory load distribution divided between the tooth and implant. This paper reports a clinical case of patient with an implant/tooth-supported overdenture and elucidates the masticatory efficiency by electromyography activity analysis. The objective of this case report was to describe a clinical case of a patient with an implant/tooth-supported overdenture and to discuss the muscle response to this treatment. Electrical activities of the masseter and anterior temporal surfaces at maximum voluntary contraction were evaluated by electromyography during pre-treatment, immediately post-treatment,15 and 60 days after installation. When patienthas one remaining tooth in good condition, theimplant/tooth-supported overdenture can be recommended, to preserve the periodontal ligament and proprioception, and to minimize bone loss. Electromyography analysis showed that implant/tooth-supported overdenture is a viable treatment alternative, in muscular stand point, when the patient has a remaining tooth with good osseous support...

Os dentistas podem encontrar casos em que o paciente possui apenas um dente mandibular remanescente,sendo difícil decidir se o dente deverá ser extraído. Quando o clínico decide manter este dente, é comum surgirem dúvidas sobre como ocorre a distribuição da carga mastigatória em próteses suportadas por dente e implante. Este artigo relata a resposta muscular por meio de atividade eletromiográfica de um paciente reabilitado com uma prótese inferior implantodentossuportada. O objetivo deste artigo foi descrever este caso clínico e discutir a resposta musculatória neste tipo de tratamento. As atividades eletromiográficas dos músculos massetere temporal anterior superficial foram avaliadas durante o pré-tratamento, imediatamente após a instalação da prótese, 15 e 60 dias pós-tratamento.Foi verificado que quando o paciente tem um dente remanescente em condição de ser mantido, a prótese implantodentossuportada pode ser recomendada como tratamento, para preservação do ligamento periodontal e da propriocepção, e para minimizar a perda óssea. A análise eletromiográfica demonstrou que a prótese implantodentossuportada é uma alternativa viável de tratamento, do ponto de vista muscular, quando o paciente possui um dente remanescente com suporte ósseo adequado...

Shear bond strength of a ceramic to Co-Cr alloys.

STATEMENT OF PROBLEM: Different combinations of Co-Cr alloys bonded to ceramic have been used in dentistry; however, the bond strength of ceramic to metal can vary because of different compositions of these alloys. PURPOSE: The purpose of this study was to evaluate the shear bond strength of a dental ceramic to 5 commercially available Co-Cr alloys. MATERIAL AND METHODS: Five Co-Cr alloys (IPS d.SIGN 20, IPS d.SIGN 30, Remanium 2000, Heranium P, and Wirobond C) were tested and compared to a control group of an Au-Pd alloy (Olympia). Specimen disks, 5 mm high and 4 mm in diameter, were fabricated with the lost-wax technique. Sixty specimens were prepared using opaque and dentin ceramics (VITA Omega 900), veneered, 4 mm high and 4 mm in diameter, over the metal specimens (n=10). The shear bond strength test was performed in a universal testing machine with a crosshead speed of 0.5 mm/min. After shear bond testing, fracture surfaces were evaluated in a stereomicroscope under x25 magnification. Ultimate shear bond strength (MPa) data were analyzed with 1-way ANOVA and the Tukey HSD test (alpha =.05). RESULTS: The mean (SD) bond strengths (MPa) were: 61.4 (7.8) for Olympia; 94.0 (18.9) for IPS 20; 96.8 (10.2) for IPS 30; 75.1 (12.4) for Remanium; 71.2 (14.3) for Heranium P; and 63.2 (10.9) for Wirobond C. Mean bond strengths for IPS 20 and IPS 30 were not significantly different, but were significantly (P<.001) higher than mean bond strengths for the other 4 alloys, which were not significantly different from each other. CONCLUSIONS: Bond strength of a dental ceramic to a Co-Cr alloy is dependent on the alloy composition.

Influence of plaster drying on the amount of residual monomer in heat-cured acrylic resins

Aim: To evaluate the influence of plaster condition, dry or not, on the amount of residual monomerin heat-cured acrylic resin. Methods: Thirty acrylic resin specimens (65x10x3 mm) were fabricatedand randomly assigned to 5 groups (n=6). The evaluated resins were heat-cured acrylic resinsby conventional or microwave polymerization techniques and the plaster was previously dried inmicrowave oven in two groups. Each specimen was individually immersed in a test tube containingmethanol (7 days) for surface analysis. In the groups for which internal monomer was evaluated,the specimens were fragmented and the small fragments were weighed prior to immersion inmethanol. The analysis was made by high performance liquid chromatography (HPLC). Datawere analyzed by ANOVA and Tukey test (p<5%) Results: showed statistical differences amongthe groups. Conclusions: The previous plaster drying influenced the residual monomer amountshowing a decrease of these levels.

Effect of thermal treatment on the bending strength of glass ceramic/resin cement / Efeito do tratamento térmico na resistência à flexão do conjunto cerâmica vítrea/cimento resinoso

Objectives: To investigate the effect of the thermal treatment on the bending strength of ceramic bars (VM7) treated by the cementation protocol. Material and Methods: Forty ceramic bars (20 x 4 x 1.2 mm) were constructed and randomly distributed into 2 groups (n=20): NT - without treatment/control and T – with treatment (50°C above the glass transition temperature, for 15 min). All specimens underwent the cementation process in which one surface of the ceramic bar was etched (20 s) with 10% hydrofluoridric acid, followed by air-water jet washing (60 s), drying (30 s), silane agent application and resin cementation. After storage (distilled water/seven days at 37 ºC), the specimens were submitted to 3-point flexure test at 100% humidity/37 ºC (v=1 mm/min, load cell of 10 kgf). Results: The bending strength values and standard deviations (MPa) were: NT: 19.98 (3.17)a; T: 20.45 (4.67)a (one-way ANOVA and Tukey test, σ=0.05). Conclusions: The thermal treatment did not influence on the bending strength mean values of the ceramics studied.

Objetivos: Investigar o efeito do tratamento térmico, na resistência à flexão, de barras cerâmicas (VM7) tratadas pelo protocolo de cimentação. Material e Métodos: Foram confeccionadas 40 barras cerâmicas (20 x 4 x 1.2 mm) e distribuídas randomicamente em 2 grupos (n=20): NT - sem tratamento/controle e T - com tratamento (50°C acima da temperatura de transição de fases, durante 15 min). Todos os espécimes receberam o processo de cimentação onde uma face da barra cerâmica foi condicionada (20 s) com ácido fluorídrico 10%, seguida pela lavagem jato ar-água (60 s), secagem (30 s), aplicação do silano e cimentação resinosa. Após armazenagem (água destilada/sete dias à 37 ºC), as amostras foram submetidas ao ensaio de flexão 3 pontos em 100% umidade à 37 ºC (v=1 mm/min, célula de carga de 10 kgf). Resultados: Os valores de resistência à flexão e os desvios-padrão (MPa) para os grupos foram: NT: 19.98 (3.17)a; T: 20.45 (4.67)a (ANOVA one-way e Teste de Tukey, σ=0.05). Conclusões: Verificou-se que o fator tratamento térmico não influenciou nos valores médios de resistência à flexão da cerâmica estudada.

Resistência à flexão e microdureza da resina acrílica quimicamente ativada submetida à tratamento por energia de micro-ondas / Flexural strength and microhardness of a chemically activated acrylic resin after microwave energy treatment

Objetivo: Avaliar o efeito do tratamento por energia de micro-ondas sobre as propriedades de resistência à flexão e microdureza da resina acrílica de ativação química Dencrilay Speed® (Dencril, Pirassununga, Brasil).Métodos: Foram confeccionados 24 corpos-de-prova separados em quatro grupos de acordo com o ciclo de tratamento por energia de micro-ondas. O G1 (controle) não recebeu tratamento algum. Os grupos G2, G3 e G4 foram imersos em 200ml de água destilada e irradiados em micro-ondas a 650W durante 5, 3 e 1 minuto, respectivamente. Cada grupo (n=6) foi submetido ao ensaio de resistência à flexão de três pontos e ao teste de microdureza Vickers (após 48 horas de armazenamento). Resultados: Os valores médios (Mpa) e desvios-padrão para o teste de resistência à flexão foram: G1 86,04 ± 10,32 a; G2 100,1 ± 5,52 ab; G3 102,04 ± 5,41 b; G4 104,81 ± 14,17 b. Os valores médios encontrados em microdureza (VHN) foram: G1- 21,98 ± 0,82 a; G2- 20,15 ± 1,24 b; G3- 19,69 ± 0,91 b; G4- 19,44 ± 0,41 b. Conclusão: O tratamento por energia de micro-ondas elevou a resistência à flexão e reduziu a microdureza da resina acrílica avaliada.

Objective: This study assessed the effectiveness of microwave energy treatment on the flexural resistance and microhardness of the chemically-activated acrylic resin Dencrilay Speed®. Methods: Twenty-four specimens were prepared and divided into 4 groups according to microwave-energy treatment cycle. G1 (control) did not receive any treatment. The specimens in groups G2, G3 and G4 were immersed in 200mL of distilled water and then microwaved in a 650W oven for 5, 3 and 1 minutes, respectively. Each group (n=6) was submitted to a three-point flexural strength test and to a Vickers hardness test after a 48-hour storage. Results: The mean values (MPa) and standard deviations for the flexural strength test were: G1 86.04 ± 10.32 a; G2 100.1 ± 5.52 ab; G3 102, 04 ± 5.41 b; G4 104.81 ± 14.17b. The mean values found for the hardness test (VHN) were: G1-21.98 ± 0.82 a; G2-20.15 ± 1.24 b; G3- 19,69 ± 0.91 b; G4-19.44 ± 0.41 b. Conclusion: Microwave treatment increased the flexural strength and reduced the microhardness of chemically-activated acrylic resins.