Deformação do colar de implantes com junta friccional – estudo qualitativo preliminar pela Espi / Deformation of the implant collar on frictional joint implants - an Espi preliminary qualitative study

A região do colar cervical do implante é constantemente exposta aos esforços mastigatórios/parafuncionais, representando uma zona em potencial à ocorrência de deformações, principalmente nos implantes de conexão interna e de reduzido diâmetro. Estas sobrecargas representam um dos fatores responsáveis pela perda óssea ao redor dos implantes. O presente estudo avaliou o comportamento do colar de implantes friccionais (Kopp) de dois diâmetros (4,3 mm e 5,5 mm) sob cargas compressivas estáticas (cêntrica e excêntrica) de duas intensidades (50 N e 100 N) por meio da Interferometria Eletrônica de Padrões de Speckle (Espi – Electronic Speckle Pattern Interferometry). A técnica Espi consiste na comparação de imagens, de antes e após o carregamento, obtidas a partir da reflexão de uma fonte de luz laser incidida sobre um objeto real de superfície rugosa, resultando em um padrão de franjas. O estudo in vitro visou testar a aplicabilidade da técnica Espi para avaliar implantes e a hipótese de que quanto maior o diâmetro do implante, maior é sua resistência ao deslocamento. Foi possível obter resultados qualitativos reprodutíveis acerca da deformação ao nível do colar do implante frente aos carregamentos, validando a técnica. Franjas horizontais foram observadas nas cargas cêntricas, demonstrando o deslocamento vertical do colar do implante e franjas diagonais nas cargas excêntricas, demonstrando o deslocamento de forma oblíqua. Estes deslocamentos podem sugerir a deformação sofrida pela amostra. A técnica Espi mostrou-se viável para avaliar as deformações da região observada e a hipótese foi confirmada, visto que no implante de menor diâmetro houve maior deformação.

The collar region of osseointegrated implants is frequently exposed to masticatory/parafunctional loads, representing a potential area subjected to deformation, especially in narrow-diameter and internal connection dental implants. This study evaluated the effect of the collar of frictional implants (Kopp) at two different diameters (4.3 mm and 5.5 mm) under static compressive loads (centric and eccentric) of two magnitudes (50 and 100 N) through the Electronic Speckle Patterns Interferometry (Espi). The Espi is a technique still little used in dentistry that consists in comparing images before and after loading, obtained from the reflection of a laser light source focused on a real object surface resulting in a fringe pattern. The in vitro study aimed to test the applicability of the ESPI technique and the hypothesis that as larger is the implant diameter, as greater is the resistance to strain at level of implant collar. It was possible to obtain reproducible qualitative results about the deformation of the implant collar when subjected to loading, validating this technique. Fringes were observed horizontally in the centric loads and diagonally in eccentric loads. These results may suggest the deformation suffered by the sample. The Espi technique was feasible to assess the deformation of the region observed and the hypothesis was confirmed, since the smaller implant diameter presented greater strain.

Modelo de remodelación ósea: un análisis computacional / Model of bone remodeling: a computed analysis

En este trabajo se tomó el modelo de remodelación ósea propuesto por Jacob (1994) y se implementó en un programa de elementos finitos con el empleo de una subrutina de usuario (UMAT), este se aplicó a un modelo 2D de un hueso genérico con un sistema de cargas para comprobar los efectos de la remodelación y las variaciones de los valores de densidad. Como parte del trabajo fueron creados 2 programas para el procesamiento de los datos, para un análisis de resultados fuera del programa de elementos finitos; se logró una apreciación cualitativa y cuantitativa de los resultados obtenidos

This paper takes the bone remodeling model proposed by Jacob (1994) and is implemented in a finite element program using a user subroutine (UMAT), and applied to a 2D model of a generic bone with a system of charges to test the effects of remodeling and changes in the density values. As part of this work were created two programs for processing data for analysis of results outside the finite element program, achieving a qualitative and quantitative assessment of the results

Modelo de remodelación ósea: un análisis computacional / Model of bone remodeling: a computed analysis

En este trabajo se tomó el modelo de remodelación ósea propuesto por Jacob (1994) y se implementó en un programa de elementos finitos con el empleo de una subrutina de usuario (UMAT), este se aplicó a un modelo 2D de un hueso genérico con un sistema de cargas para comprobar los efectos de la remodelación y las variaciones de los valores de densidad. Como parte del trabajo fueron creados 2 programas para el procesamiento de los datos, para un análisis de resultados fuera del programa de elementos finitos; se logró una apreciación cualitativa y cuantitativa de los resultados obtenidos(AU)

This paper takes the bone remodeling model proposed by Jacob (1994) and is implemented in a finite element program using a user subroutine (UMAT), and applied to a 2D model of a generic bone with a system of charges to test the effects of remodeling and changes in the density values. As part of this work were created two programs for processing data for analysis of results outside the finite element program, achieving a qualitative and quantitative assessment of the results(AU)

Mastication effort study using photorefractive holographic interferometry technique.

The purpose of this work was the force-displacement response analysis of the masticatory process in a dried human skull by Double-Exposure Photorefractive Holographic Interferometry Technique (2E-PRHI). The load concentration and dissipation of the forces from dried human skull were analysed at applied loading stands as a Simulation of Isolated Contraction (SIC) of some mastication muscles. The 2EHI and Fringe Analysis Method were used to obtain the quantitative results of this force-displacement response. These results document quantitatively the real biomechanical response from dried human skull under applied loading and it can be used for complementary study by finite element model and others analysis type.

The optical analysis of the abdominal wall using the biospeckle after implants of polypropylene mesh in rats.

PURPOSE: To evaluate an experimental animal model to study the abdominal tissue activity considering its interaction with a polypropylene mesh, through the use of one of the optical phenomena of light Laser, the biospeckle. METHODS: Fifty Wistar male rats were divided into four groups: Group 1: ten animals not submitted to surgery; Group 2: ten animals submitted to surgery without polypropylene mesh; Group 3: 20 animals submitted to surgery followed by the mesh placement; Group 4: (sham) with ten animals. None of the animals presented post surgical complications being submitted to the optical tests at the 20th postoperative day. RESULTS: The analysis from the biospeckle tests, comparing the medians and standard deviations with T Student test, indicated that no significative difference was observed on the abdominal wall tissue activity in the four groups considered, with and without polypropylene mesh prosthesis implantation. CONCLUSION: The animal model is viable and the biospeckle open ways for a great number of experiments to be developed in evaluating tissue activity.

The optical analysis of the abdominal wall using the biospeckle after implants of polypropylene mesh in rats / Análise ótica da parede abdominal pelo biospeckle após implante de prótese de polipropileno em ratos

PURPOSE: To evaluate an experimental animal model to study the abdominal tissue activity considering its interaction with a polypropylene mesh, through the use of one of the optical phenomena of light Laser, the biospeckle. METHODS: Fifty Wistar male rats were divided into four groups: Group 1: ten animals not submitted to surgery; Group 2: ten animals submitted to surgery without polypropylene mesh; Group 3: 20 animals submitted to surgery followed by the mesh placement; Group 4: (sham) with ten animals. None of the animals presented post surgical complications being submitted to the optical tests at the 20th postoperative day. RESULTS: The analysis from the biospeckle tests, comparing the medians and standard deviations with T Student test, indicated that no significative difference was observed on the abdominal wall tissue activity in the four groups considered, with and without polypropylene mesh prosthesis implantation. CONCLUSION: The animal model is viable and the biospeckle open ways for a great number of experiments to be developed in evaluating tissue activity.

OBJETIVO: Avaliar o modelo experimental animal para o estudo da atividade tecidual da parede abdominal em sua interação com a prótese de polipropileno, através da utilização de um dos fenômenos ópticos da luz Laser, o biospeckle. MÉTODOS: Foram utilizados 50 ratos Wistar machos, divididos em quatro grupos: Grupo 1 com 10 animais não operados e controles; Grupo 2 com 10 animais submetidos a cirurgia sem a colocação de prótese; Grupo 3 com 20 animais submetidos a cirurgia com colocação de prótese de polipropileno pré-peritonial; Grupo 4 (Sham) com 10 animais. Nenhum animal apresentou complicações pós-operatórias, sendo que no 20º PO foram submetidos ao ensaio óptico. RESULTADOS: A comparação das médias e o desvio padrão das medidas da atividade tecidual da parede abdominal, com e sem implantação da prótese de polipropileno obtidas dos grupos de animais, pelo teste T de Student, não evidenciou diferença estatística significativa (p>0.05). CONCLUSÃO: A análise dos dados obtidos permitiu concluir que o modelo animal é viável e que o biospeckle abre caminhos para toda uma linha de experimentos a ser desenvolvida em avaliar atividade tecidual.

Phase-shifting real-time holographic interferometry applied to load transmission evaluation in dried human skull.

Phase-shifting real-time holography with photorefractive Bi(12)SiO(20) crystal as holographic recording medium applied to load transmission evaluation and tension dissipation on a dried human skull under loading is presented. The applied loading stands as a simulation of isolated contraction (SIC) of some masticatories muscles. The four-frames phase-shifting technique and the unwrapping branch-cut technique were used to obtain the phase map. The quantitative results show the feasibility of the employed system in the study of microdisplacements in the skull structure provided by SIC.

Holographic interferometry method for assessment of static load stress distribution in dog mandible.

This study compared the transmission of tensions in fresh, fixed and macerated dog mandibles in order to clarify the diversity of behavior of bone tissues under dry and moist conditions. Double-exposure holographic interferometry was applied and holograms were obtained from 12 fresh hemi-mandibles under static load (control group), which were randomly assigned to 2 groups: 6 were fixed in 10% formalin and 6 were macerated. The specimens were submitted to the same initial force and their respective holograms were obtained. Analysis of the holograms showed that the fresh specimens transmitted significantly less tension than the fixed and macerated ones (p<0.05), and the tension direction was different. An average two-fold tension increment was observed in the experimental conditions. The holographic interferometry method was efficient in quantifying and qualifying tension transmission. However, depending on the type of analysis, the anatomical specimens must be fresh because macerated specimens will produce different results.

Holographic interferometry method for assessment of static load stress distribution in dog mandible

This study compared the transmission of tensions in fresh, fixed and macerated dog mandibles in order to clarify the diversity of behavior of bone tissues under dry and moist conditions. Double-exposure holographic interferometry was applied and holograms were obtained from 12 fresh hemi-mandibles under static load (control group), which were randomly assigned to 2 groups: 6 were fixed in 10 percent formalin and 6 were macerated. The specimens were submitted to the same initial force and their respective holograms were obtained. Analysis of the holograms showed that the fresh specimens transmitted significantly less tension than the fixed and macerated ones (p<0.05), and the tension direction was different. An average two-fold tension increment was observed in the experimental conditions. The holographic interferometry method was efficient in quantifying and qualifying tension transmission. However, depending on the type of analysis, the anatomical specimens must be fresh because macerated specimens will produce different results.

Frente à diversidade de comportamento do tecido ósseo, nas condições seca e úmida, este trabalho comparou a transmissão de tensões em mandíbulas de cães nas seguintes condições: frescas, fixadas e maceradas. Aplicou-se a interferometria holográfica de dupla exposição e os hologramas foram obtidos de 12 hemi-mandíbulas, sob carregamento estático (grupo controle). Em seguida, foram randomizadas em 2 grupos: 6 hemi-mandíbulas foram fixadas em solução de formol a 10 por cento e 6 foram maceradas. As amostras foram submetidas à mesma carga inicial e os respectivos hologramas foram obtidos. A análise dos hologramas mostrou que as amostras frescas transmitiram menos tensão que as amostras fixadas e as maceradas (p<0,05), e também houve diferença na direção percorrida pelas tensões. Em média, os grupos experimentais apresentaram o dobro de tensões em relação ao grupo controle. O método da interferometria holográfica mostrou-se eficiente para avaliar quantitativa e qualitativamente a transmissão das tensões geradas. Entretanto, dependendo do tipo de análise, a peça anatômica deve ser fresca, uma vez que os resultados podem diferir das amostras secas.

Qualitative analysis of stress distribution in tooth-implant and implant-supported prosthesis by means of holography interferometry method

Natural teeth and dental implants cause non-uniform distribution of stress when connected in prosthesis. Understanding of biomechanical behavior is necessary for an adequate choice and construction of this type of rehabilitation. The purposeof this study was to compare the stress distribution between implant and tooth-implant-supported prosthesis under static load by means of holographic interferometry method. Tooth-implant and implant supported prosthesis were placed on osseointegrated implants in dog mandibles (Canis familiaris). So, the animals were sacrificed (in vitro test) and static load was applicated on the prosthesis, holograms were obtained by means of interferometry holographic method. A qualitative comparison of holograms was realized for both types of prosthesis. In the case of implant-supported prosthesis, the deflection fringes were observed in both abutment connections. For tooth-implant-supported prosthesis, only deflection fringes in the abutment-implant connection were observed. No fringes were observed in the dental abutment. The stress distributions in the implant-supported and tooth-implant prosthesis were homogeneous and non-homogeneous, respectively. The adequate choice of the prosthesis should be based on the analysis of all advantages and disadvantages of each type of prosthesis.

Single-exposure, photorefractive holographic surface contouring with multiwavelength diode lasers.

We studied the use of multiwavelength diode lasers for surface profilometry through holographic recording in sillenite Bi12TiO20 crystals. When such lasers are used, the holographic image from single-exposure recordings appears covered with interference fringes providing information on the surface relief of the object. By taking advantage of the narrow interference fringes due to the multiwavelength emission of the laser, we obtained interferograms by holographic recording with two reference beams, which improves the surface analysis by visual inspection and enhances the profilometry sensitivity.