Stress analysis in oral obturator prostheses: Imaging photoelastic

Maxillary defects resulting from cancer, trauma, and congenital malformation affect the chewing efficiency and retention of dentures in these patients. The use of implant-retained palatal obturator dentures has improved the self-esteem and quality of life of several subjects. We evaluate the stress distribution of implant-retained palatal obturator dentures with different attachment systems by using the photoelastic analysis images. Two photoelastic models of the maxilla with oral-sinus-nasal communication were fabricated. One model received three implants on the left side of the alveolar ridge (incisive, canine, and first molar regions) and the other did not receive implants. Afterwards, a conventional palatal obturator denture (control) and two implant-retained palatal obturator dentures with different attachment systems (O-ring; bar-clip) were constructed. Models were placed in a circular polariscope and a 100-N axial load was applied in three different regions (incisive, canine, and first molar regions) by using a universal testing machine. The results were photographed and analyzed qualitatively using a software (Adobe Photoshop). The bar-clip system exhibited the highest stress concentration followed by the O-ring system and conventional denture (control). Images generated by the photoelastic method help in the oral rehabilitator planning. © 2013 SPIE.

Histologic and biomechanical evaluation of 2 resorbable-blasting media implant surfaces at early implantation times

This study evaluated 3 implant surfaces in a dog model: (1) resorbable-blasting media + acid-etched (RBMa), alumina-blasting + acid-etching (AB/AE), and AB/AE + RBMa (hybrid). All of the surfaces were minimally rough, and Ca and P were present for the RBMa and hybrid surfaces. Following 2 weeks in vivo, no significant differences were observed for torque, bone-to-implant contact, and bone-area fraction occupied measurements. Newly formed woven bone was observed in proximity with all surfaces.

Rehabilitation of maxillary cleft with hybrid obturator prosthesis

The hybrid obturator prosthesis aims to provide a sense of well-being to the patient, offering improvements in speech, chewing, and swallowing. Thus, the retention and stabilization of the prosthesis become decisive factors for the success of the rehabilitation treatment. The objective of this study was to describe the treatment of a 70-year-old man with a congenital maxillary cleft performed through aesthetic and functional prosthetic rehabilitation with hybrid obturator prosthesis. In this study, the fabricated prosthesis achieved its purpose by providing adequate functional and aesthetic conditions to the patient, promoting the reduction of airspace through the sealing of the oronasal communication, with consequent improvement in the quality of life. Copyright © 2013 by Mutaz B. Habal, MD.

Biocompatibility of Ferrara intracorneal ring segment with and without chondroitin sulfate coating: Clinical and histopathological evaluation in rabbits

PURPOSE: To investigate and compare the biocompatibility of two types of Ferrara intracorneal ring segment: with and without chondroitin sulfate coating by clinical and histopathological evaluation. METHODS: A randomized experimental study was carried out on thirty right-eye corneas from 30 Norfolk albino rabbits allocated into two experimental groups: Group G1 - implanted with Ferrara intracorneal ring segment without coating (FICRS) and Group G2 - implanted with Ferrara intracorneal ring segment with chondroitin sulfate coating (FICRS-CS). Left eyes formed the control group. Clinical parameters analyzed were: presence of edema, vascularization, infection and ring extrusion one, 30, and 60 days after surgery. Histopathological parameters analyzed were: number of corneal epithelial layers over and adjacent to the ring, presence of spongiosis, hydropic degeneration, basement membrane thinning, inflammatory cells, neovascularization and pseudocapsule formation. RESULTS: At clinical examination 60 days after implant, edema, vascularization and extrusion were observed respectively in 20%, 26.7%, 6.7% of FICRS corneas and in 6.7%, 6.7%, and 0% of FICRS-CS corneas. Histopathological evaluation showed epithelial-layer reduction from 5 (5;6) to 3 (3;3) with FICRS and from 5 (5;5) to 4 (3;5) with FICRS-CS in the region over the ring. Epithelial spongiosis, hydropic degeneration, and basement membrane thinning were present in 69.2%, 53.8%, and 69.2% of FICRS and in 73.3%, 73.3%, and 46.7% with FICRS-CS, respectively. Vascularization was present in 38.5% of FICRS and 13.3% with FICRS-CS, inflammatory cells in 75% of FICRS and 33.3% with FICRS-CS, and pseudocapsule in 66.7% of FICRS and 93.3% with FICRS-CS. Giant cells occurred only in the FICRS-CS group (20%). CONCLUSION: Ferrara intracorneal rings coated with chondroitin sulfate (FICRS-CS) caused lower frequency of clinical and histopathological alterations than Ferrara intracorneal rings without the coating (FICRS), demonstrating higher biocompatibility of the FICRS-CS.

Implant-abutment gap versus microbial colonization: Clinical significance based on a literature review

Microorganisms from the oral cavity may settle at the implant-abutment interface (IAI). As a result, tissue inflammation could occur around these structures. The databases MEDLINE/PubMed and PubMed Central were used to identify articles published from 1981 through 2012 related to the microbial colonization in the implant-abutment gap and its consequence in terms of crest bone loss and osseointegration. The following considerations could be put forward, with respect to the clinical importance of IAI: (a) the space present at the IAI seems to allow bacterial leakage to occur, in spite of the size of this space; (b) bacterial leakage seems to occur at the IAI, irrespective of the type of connection. More studies are necessary to clarify the relationship between leakage at IAI and abutment connection designs; (c) losses at the peri-implant bone crests cannot be related to the IAI size, since few studies have shown no relationship. Also, the microbial leakage at the IAI cannot be related to the bone crest loss, since there are no articles reporting this relationship; remains controversial the influence of the IAI position on the bone crest losses. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 101B: 1321-1328, 2013. Copyright © 2013 Wiley Periodicals, Inc.

Stress analysis in bone tissue around single implants with different diameters and veneering materials: A 3-D finite element study

The aimof this study was to evaluate the stress distribution on bone tissue with a single prosthesis supported by implants of large and conventional diameter and presenting different veneering materials using the 3-D finite elementmethod. Sixteenmodels were fabricated to reproduce a bone block with implants, using two diameters (3.75 × 10 mmand 5.00 × 10 mm), four different veneering materials (composite resin, acrylic resin, porcelain, and NiCr crown), and two loads (axial (200 N) and oblique (100 N)). For data analysis, the maximum principal stress and vonMises criterion were used. For the axial load, the cortical bone in allmodels did not exhibit significant differences, and the trabecular bone presented higher tensile stresswith reduced implant diameter. For the oblique load, the cortical bone presented a significant increase in tensile stress on the same side as the loading for smaller implant diameters. The trabecular bone showed a similar but more discreet trend. There was no difference in bone tissue with different veneering materials. The veneering material did not influence the stress distribution in the supporting tissues of single implant-supported prostheses. The large-diameter implants improved the transference of occlusal loads to bone tissue and decreased stress mainly under oblique loads.Oblique loading was more detrimental to distribution stresses than axial loading. © 2013 Elsevier B.V. All rights reserved.

O uso de implantes orbitários no reparo de cavidades anoftálmicas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Implante de cimento de alfa-fosfato tricálcico de dupla pega munido de canais de interconexão em órbita de coelhos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação da biocompatibilidade de vários elastômeros de silicone implantados no tecido subcutâneo de ratos: estudo histológico e histomorfométrico

Pós-graduação em Odontologia - FOA

Avaliação clínica e radiográfica dos tecidos peri-implantares de implantes osseointegrados que receberam carregamento imediato

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise estrutural dos efeitos da desadaptação em componentes de próteses odontológicas utilizando o método dos elementos finitos com elemento de contato e pré-carga

Pós-graduação em Engenharia Mecânica - FEB

Análise numérica de interfaces de próteses dentárias através da mecânica do dano

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Precisão das técnicas de moldagem e vazamento para próteses implantossuportadas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Novo formato de pilar protético em zircônia estabilizada por Itría (Y-Tzp) para implantodontia desenvolvido pela técnica de slip casting

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Extensometria: estudo das deformações ao redor de três implantes cone morse, com posicionamento linear, sob carga axial

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)