Influence of the unilateral angular misfit in frameworks made of UCLA on the peri-implant strain distribution, subjected to preload and axial load

Atualmente, os implantes são utilizados em diversos tipos de tratamento na reabilitação oral. Para manutenção da osseointegração, é essencial que o conjunto prótese/implante/osso seja submetido a forças às quais estejam aptos a suportar. Os diferentes tipos de desadaptações das infraestruturas das próteses sobre implantes são fatores que podem contribuir para o aumento das tensões na região peri-implantar. Este estudo teve como objetivo avaliar a influência das desadaptações angulares unilaterais na distribuição de tensões na região periimplantar de pilares tipo UCLA, no momento da pré-carga e carga axial. Infraestruturas de CoCr, confeccionadas utilizando-se pilares tipo UCLA, foram divididas em quatro grupos: Grupo A (adaptado), Grupo B, Grupo C e Grupo D (50, 100 e 200 &#x3BC;m de desadaptação unilateral angular por vestibular, respectivamente). Cada grupo foi representado por quatro infraestruturas (n=4). Quatro implantes (4.1mm/15mm) foram posicionados em uma matriz metálica, onde posteriormente foi vazado o poliuretano (PU), com função de simular o tecido ósseo. Quatro extensômetros (strain gauges) foram posicionados na região vestibular, distal, lingual e mesial de cada implante, para aferir a quantidade de deformação; cada grupo foi posicionado em seu respectivo implante. Foram realizados dois testes: o teste de pré-carga com um torque de 32Ncm e o teste de carga com uma força axial estática de 300N. Cada infraestrutura foi sujeita aos dois testes, por cinco vezes. Para análise estatística dos dados, foram utilizados ANOVA (dois critérios) e o teste de Tukey (p<0,05). Os resultados mostraram que os grupos A e B tiveram menos deformação da região peri-implantar em ambos os testes, quando comparados aos grupos C e D. A estatística também mostrou que o Grupo A apresentou melhor distribuição de tensões em sua região, peri-implantar quando comparado aos outros três grupos (p<0,05). Como conclusões, este estudo mostrou que as desadaptações influem na distribuição das tensões da região peri-implantar e que quanto maior o nível de desadaptação, mais altas são as tensões geradas.Nowadays implants are used in several kinds of oral rehabilitation treatments. For the osseointegration maintenance it is important that crow/implant/bone are subjected to forces which are able to withstand. Different kinds of misfit on the crown frameworks are factors that could lead to an increase of strain around the implanted bone. This study aimed to evaluate the influence of the unilateral angular misfit in frameworks made of UCLA on the peri-implant strain distribution, subjected to preload and axial load. Frameworks made of chrome-cobalt were fabricated on UCLA abutments and divided in 4 groups: Group A (no misfit), Group B, Group C, Group D (50, 100, and 200 of unilateral angular misfit by buccal side, respectively). Each group was represented for 4 frameworks (n=4). Four implants (4.1mm/15mm) were positioned in a metallic matrix which was subsequently poured the polyurethane (PU) to simulate the bone. Four strain gauges were positioned on the buccal, distal, lingual and mesial sides of each implant to assess the amount of strain, each group was connected on its respectively implant. It was performed 2 tests: the preload test with a 32Ncm torque and the load test by applying an axial force of 300N. Each framework was subjected to the both test five times. To the statistics analysis ANOVA (2 ways) and Turkeys test were performed. The results showed that the Groups A and B presented less deformation when compared to Groups C and D. The statistics also showed that the Group A presented better distribution of strain on its peri-implant bone when compared to the other three groups (p<0,05). In conclusion this study showed that misfit had influence on the strain distribution on the peri-implant bone and that strain increased on the Groups C and D which presented higher levels of misfit

Deformation of Implant Abutments After Framework Connection Using Strain Gauges

When a cylinder is connected to an abutment it is expected that abutment and cylinder will be subjected to compression forces throughout their periphery because of the clamping force exerted by the screw. The deformation resultant of this compression should be measurable and uniform along the periphery of the abutment. Considering that multiple retainers connected to each other can affect the fit of a framework, as well as the use of different alloys, it is expected that the abutments will present different levels of deformation as a result of framework connection. The aim of this study was to evaluate the deformation of implant abutments after frameworks, cast either in cobalt-chromium (CoCr) or silver-palladium (AgPd) alloys, were connected. Samples (n = 5) simulating a typical mandibular cantilevered implant-supported prosthesis framework were fabricated in cobalt-chromium and silver-palladium alloys and screwed onto standard abutments positioned on a master-cast containing 5 implant replicas. Two linear strain gauges were fixed on the mesial and distal aspects of each abutment to capture deformation as the retention screws were tightened. A combination of compressive and tensile forces was observed on the abutments for both CoCr and AgPd frameworks. There was no evidence of significant differences in median abutment deformation levels for 9 of the 10 abutment aspects. Visually well-fit frameworks do not necessarily transmit load uniformly to abutments. The use of CoCr alloy for implant-supported prostheses frameworks may be as clinically acceptable as AgPd alloy.CNPq (Agency of the Brazilian Ministry of Education)CNPq (Agency of the Brazilian Ministry of Education) [300666/93-4]FAPESF (Research Support Foundation of the State of Sao Paulo) [99/01402-6, 05/56182-3]FAPESF (Research Support Foundation of the State of Sao Paulo

Color evaluation of a resin cement light polymerized by different light sources and submitted to potentially staining beverages

Abstract Introduction The color stability of resin cements, whether dual-pre-cured or photopolymerizable, as well as the color of the dental substrate, are fundamental for the aesthetic success of ceramic restorations, since the ceramic presents a high level of translucency due to its small thickness. Objective The aim of this in vitro study was to evaluate the color of a resin cement light polymerized by different light sources and immersed in potentially staining beverages. Material and method Were made 42 specimens of resin cement Variolink-Esthetic (2×6mm) (n=7), being half polymerized with LED light (F1) and half with Halogen light (F2). The specimens were stored in artificial saliva at 37 °C±1 °C. After 24 hours, they were polished with abrasive discs, and divided for the purpose of being submitted to the different solutions for 2 minutes per day, for 28 days, as follows: S1 – Coca-Cola; S2 – Red Wine; and S3 – Distilled Water (Control). Five color readouts were taken: T0 – initial; T1 – 7 days; T2 – 14 days; T3 – 21 days; and T4 – 28 days; with a spectrophotometer (Model SP62S). The color change data (ΔE*) were submitted to statistical analysis, ANOVA and Tukey (p≤0.05). Result Analyzing the factor solution, S2 (5.89 (±0.02)), produced a higher ΔE* value than S1 (3.79 (±0.02)) and (S1), a higher value than S3 (1.41 (±0.02)). Analyzing the factor light source, F2 (4.05 (±0.12)), produced a higher ΔE* value than F1 (3.33 (±0.12)). When analyzing the factor time, ΔE* values were found to increase gradually over the course of time: T1(2.36 (±0.08)); T2(3.27 (±0.08)); T3(4.06 (±0.08)); and T4(5.09 (±0.08)). Conclusion It was concluded that red wine produced a greater color change; Halogen light promoted highest degree of pigmentation; and the longer the time of immersion, the greater the color change of the material

O impacto das condições bucais na qualidade de vida de pessoas com cinquenta ou mais anos de vida The impact on life quality due to oral conditions in people fifty years or above

Avaliou-se a influência de variáveis sociodemográficas e as condições bucais na qualidade de vida de 224 indivíduos, com 50 anos ou mais de Bauru (SP). Os dados foram coletados de acordo com o Oral Health Surveys-Basic Methods: índices de cárie, periodontal comunitário, perda de inserção periodontal e uso/necessidade de próteses odontológicas. A percepção do indivíduo sobre suas condições bucais, foi medida pelo Oral Health Impact Profile, com sete domínios: limitação funcional, dor, desconforto psicológico, incapacidades física, psicológica e social e desvantagem. 60% dos indivíduos eram aposentados; 42% sem atividade social; 65,5% com renda mensal de um a três salários mínimos; 53% usavam prótese total superior e, destes, 33% ambas; 1,94 dentes cariados e 5,4 restaurados; OHIP-os impactos sociais foram menos intensos que os físicos/ psicológicos; a idade foi significante em todos os domí­nios; apenas a condição periodontal foi importante para a qualidade de vida. As variáveis sociodemográficas e as condições bucais tiveram pequena variação no OHIP; os impactos sociais foram menos intensos que os físicos/psicológicos na qualidade de vida; a maioria dos entrevistados acusou pelo menos um impacto da saúde bucal na qualidade de vida; os escores do OHIP diminuíram nos grupos de maior idade.<br>The objective of this work was to evaluate the influence of socio-demographic variables and oral health conditions in the quality of life of non-institutionalized people aged 50 or above, living in Bauru, São Paulo State. Clinical oral examinations were conducted on a sample of 224 people including dental caries, periodontal disease and usage or need of dental prosthesis according to WHO suggestions for community dental health surveys. They were also asked to answer a questionnaire comprised of 49 questions about the impact of their oral status on the activities of daily living (OHIP). Descriptive statistics and multiple regression analysis were computed with individual scores of each domain as dependent variables. The results were: 60% were retired people, 42% exercise no social activity and 65.5% earned less than three minimum wages. Dentate people had a mean of 15.3 missing teeth, 117 people (53% of the sample) had full dentures. It could be concluded that regression analysis showed no socio-demographic variable but age having a significant impact on quality of life; as people get older oral disorders seems to produce lower impact on quality of life. As it concerns to oral clinical data only periodontal disease showed impact on quality of life