A three-dimensional finite element analysis to evaluate stress distribution tooth in tooth implant-supported prosthesis with variations in non-rigid connector design and location

The physiologically mobile natural tooth and rigidly fixed dental implant causes different distribution of stress when connected in prosthesis and nonrigid connector compensates this. Understanding of biomechanical behavior is necessary for an adequate choice and construction of this type of rehabilitation. However, there has been insufficient research focusing on different location and type of the nonrigid connector related with the prognosis of both implant and the tooth. Aim of the Study: The purpose of this finite element (FE) analysis was to evaluate the stress distribution around bone, implant, and tooth in tooth implant fixed prosthesis under static load with variations in design and location of nonrigid connectors under simulated functional loads. Materials and Method: Three, 3-dimensional FE models connecting tooth and implant were constructed with different location and type of nonrigid connector. Simulated occlusal load was applied on the restorations and stresses developed in the supporting structures were monitored. Results: The highest stresses were found around the implant in model with nonrigid connector placed between the tooth and implant and model with modified nonrigid connector. On the other hand, less stress was noted around the implant where nonrigid connector was placed between the implant and pontic. Conclusion: It is advisable to place the nonrigid connector between the implant and the pontic to protect the implant from torque effects in a tooth implant fixed prosthesis.

The modified lip-tooth-ridge classification: a guide for edentulous maxillary arches / 华西口腔医学杂志

According to the width and height of the maxillary alveolar ridge, the maxillary edentulous jaws can be divided into three categories by using modified lip-tooth-ridge (MLTR) classification. Class Ⅰ is characterized by sufficient bone available for implants in the vertical and horizontal aspects and is suitable for fixed implant-supported prostheses. Class Ⅱ is characterized by sufficient bone amount available for implants in a horizontal aspect but insufficient for lip support and is suitable for a fixed detachable implant-supported prosthesis. Class Ⅲ is characterized by inadequate amount of bone for implants (with vertical or horizontal components) and is suitable for the use of zygomatic implants or traditional complete denture. Patients belonging to Class Ⅰ can be further classified into two sub-categories according to the height of the alveolar ridge. The first subclass is characterized by minimal bone deficiency and is suitable for a conventional implant-supported "crown and bridge" prosthesis. The second subclass is characterized by a larger vertical deficiency than that of the first subclass and is suitable for implant-supported hybrid prosthesis. The MLTR classification system can help the dentist to determine whether the patient is suitable for implanting dentures and whether fixed denture or removable denture is appropriate for the patient, select indications, reduce complications, and achieve long-term results.

Tensile Strength of Resin Cements Used with Base Metals in a Simulating Passive Cementation Technique for Implant-Supported Prostheses

Abstract The aim of this study was to analyze the tensile strength of two different resin cements used in passive cementation technique for implant-supported prosthesis. Ninety-six plastic cylinders were waxed in standardized forms, cast in commercially pure titanium, nickel-chromium and nickel-chromium-titanium alloys. Specimens were cemented on titanium cylinders using self-adhesive resin cement or conventional dual-cured resin cement. Specimens were divided in 12 groups (n=8) in accordance to metal, cement and ageing process. Specimens were immersed in distilled water at 37 °C for 24 h and half of them was thermocycled for 5,000 cycles. Specimens were submitted to bond strength test in a universal test machine EMIC-DL2000 at 5 mm/min speed. Statistical analysis evidenced higher tensile strength for self-adhesive resin cement than conventional dual-cured resin cement, whatever the used metal. Self-adhesive resin cement presented higher tensile strength compared to conventional dual-cured resin cement. In conclusion, metal type and ageing process did not influence the tensile strength results.

Resumo O objetivo deste estudo foi analisar a resistência à tração de dois diferentes cimentos resinosos usados na técnica de cimentação passiva de próteses implanto-suportadas. Noventa e seis cilindros plásticos foram encerados em formas padronizadas, fundidos em titânio grau 2 comercialmente puro e ligas de níquel-cromo e níquel-cromo-titânio. Amostras foram cimentadas sobre cilindros de titânio usando um cimento auto-adesivo ou um cimento convencional de dupla polimerização. Os espécimes foram divididos em 12 grupos (n=8) de acordo com o metal, cimento e processo de envelhecimento. Espécimes foram imersos em água destilada a 37 °C por 24 h e metade deles foi termociclado por 5,000 ciclos. Espécimes foram submetidos ao ensaio de tração numa máquina universal de ensaios (velocidade de 5 mm/min). Análise estatística evidenciou maior resistência à tração do cimento auto adesivo do que o cimento convencional de dupla polimerização, independente do metal utilizado. O cimento resinoso auto adesivo apresentou maior resistência à tração do que o cimento convencional de dupla polimerização. O tipo de metal e o processo de envelhecimento não tiveram influência nos resultados.

Uso do enxerto ósseo alógeno de banco de tecidos para reconstrução extensa da maxila e reabilitação com prótese fixa aparafusada: controle clínico e radiográfico após oito anos / The use of tissue-bank allogeneic bone grafts for large maxillary reconstruction and rehabilitation with a complete fixed prosthesis: an 8-year clinical and radiographic follow-up

Este caso clínico relata uma reconstrução extensa na maxila de um paciente de 45 anos de idade, portador de prótese total superior e dentição natural inferior, feita com enxertos alógenos previamente à colocação de uma prótese total fixa parafusada. Inicialmente, peças corticoesponjosas de fíbula (4 mm x 15 mm), obtidas no mesmo bancos de ossos, foram colocadas na região anterior do rebordo. As membranas dos seios maxilares foram levantadas para colocação de osso particulado. Seis meses depois, implantes entre 13 mm e 15 mm de comprimento foram usados, sendo de largo diâmetro (5 mm) nas regiões posteriores. Após mais seis meses, a prótese definitiva foi colocada. O controle clínico e radiográfico de oito anos mostrou a estabilidade dos tecidos e ausência de complicações mecânicas na reabilitação.

This clinical case reports a large maxillary reconstruction for a 45 years-old patient wearing a complete denture against a mandibular natural dentition, performed with allograft material before an implant-supported fixed prosthesis. First, cortico-medullary pieces (4 mm x 15 mm) from a bone tissue bank were adapted to the anterior edentulous ridge. Also, both sinus membranes were lifted to accomodate particulate bone chips. Six months later, dental implants having 13-15 mm in length were installed, being the most posterior of wider diameter (5 mm). After additional six months, the defnitive prosthesis was delivered. The 8-year clinical and radiographic controls demonstrated tissue stability and the lack of mechanical complications for the oral rehabilitation.

Reabilitação oral implantossuportada ­ relato de caso / Implant supported oral rehabilitation ­ case report

Os implantes osseointegrados promoveram importantes mudanças nas formas de reabilitação de pacientes parcial ou totalmente desdentados. Os pacientes totalmente desdentados apresentam clara predileção pelas próteses fixas implantossuportadas, sobretudo porque estas proporcionam maior eficiência mastigatória e conforto, menos reparo e manu-tenção, além de favorecer o aspecto psicológico, uma vez que eliminam o caráter removível das overdentures. Dentre os possíveis desenhos de próteses fixas, as do tipo protocolo são as que apresentam maior aplicação clínica, e se caracterizam na maxila pela instalação de 6 a 8 implantes. Nesse tipo de prótese utiliza-se uma infraestrutura metálica e uma base de resina acrílica para juntá-la aos dentes artificiais. O objetivo deste trabalho foi relatar um caso clínico de reabilitação oral com prótese total fixa tipo protocolo superior e próteses unitárias metalocerâmicas inferiores, em que foram adotados critérios bem definidos de diagnóstico e planejamento, e empregadas técnicas cirúrgicas e protéticas com fundamentação científica.

Dental implants have promoted important changes on the rehabilitation of partial or complete edentulous patients. Edentulous patients have a clear preference for implantsupported prostheses, mainly because they provide greater masticatory efficiency and comfort with less repair and maintenance, besides the improvement of psychological aspect since they eliminate the removable character of overdentures. Among the possible designs of fixed prostheses, protocol-type prostheses are those with highest clinical application. This type of prosthesis in the jaw is characterized by the installation of 6 to 8 implants using a metal structure and an acrylic resin base to attach it to the artificial teeth. The objective of this study was to report a case of oral rehabilitation using a maxillary protocol-type fixed denture and mandibular metaloceramic single elements, performed with precise criteria for diagnosis and planning as well as science-based techniques.

Resistência à fratura de infraestruturas de próteses totais implantossuportadas em função de diferentes desenhos de cantilever e espessura do conector distal: estudo in vitro / Fracture resistance of infrastructure implant-supported dentures due to different design of cantilever and the thickness of the distal connector: in vitro study

O objetivo do presente trabalho foi avaliar, por meio de teste de compressão, a resistência à fratura de infraestruturas metálicas de próteses totais implantossuportadas do tipo protocolo de Branemark em função de diferentes designs (comprimentos e altura) do cantilever, bem como espessura do conector distal. Foram confeccionadas 39 infraestruturas (barras) em liga de CoCr agrupadas de acordo com o comprimento do cantilever (cc) (12mm, 19mm e 26mm), altura do cantilever (hc) (3,2 mm, 4mm) e espessura do conector distal (ec) (0,4mm, 1,5mm e 2mm). Os grupo foram divididos em Controle (cc 12mm; hc 4mm; ec 1,5),Grupo 1 (cc 12mm; hc 4mm; ec 0,4mm), Grupo 2(cc 12mm; hc 3,2mm; ec 0,4mm), Grupo 3 (cc 12mm; hc 3,2mm; ec 1,5mm), Grupo 4 (cc 19mm; hc 4mm; ec 1,5mm), Grupo 5 (cc 19mm; hc 4mm; ec 0,4mm), Grupo 6 (cc 19mm; hc 3,2mm; ec 1,5mm), Grupo 7 (cc 19mm; hc 3,2mm; ec 0,4mm), Grupo 8 (cc 26mm; hc 4mm; ec 1,5mm), Grupo 9 (cc 26mm; hc 4mm; ec 0,4mm), Grupo 10 (cc 26mm; hc 3,2mm; ec 1,5mm) e Grupo 11 (cc 26mm; hc 3,2mm; ec 0,4mm). Todos os espécimes foram submetidos a ensaio de compressão em uma maquina de ensaio universal com célula de carga de 5000N e velocidade constante de 0,5mm/min. Os dados obtidos foram submetidos a analise estatística ANOVA a três critérios, seguido pelo teste de Tukey, com nível se significância de 5% (p<0,05). Foi observada uma diferença significante na diminuição de resistência a compressão com o aumento do comprimento do cantilever, um aumento significante de resistência nos grupos com altura de cantileveres maiores. Foi concluído que quanto menor o comprimento e maior a altura do cantilever, maior será a resistência. Já a espessura do conector influenciou a resistência, porém sem uniformidade(AU)

The aim of this study was to evaluate, through compression test, the fracture strength of metal infrastructure dentures implant of the Branemark protocol type for different designs (length and height) of the cantilever and thickness of the connector distal. 39 were prepared infrastructure (bar) pooled CoCr alloy according to the length of the cantilever (cc) (12mm, 19mm and 26mm), the cantilever height (hc) (3.2mm, 4mm) thick and the distal connector ( c) (0.4mm, 1.5mm and 2mm). The group were divided into control (cc 12mm; hc 4mm and c 1.5), Group 1 (cc 12mm; hc 4mm, 0.4mm c), Group 2 (cc 12 mm; hc 3.2mm, 0.4mm and c) Group 3 (cc 12 mm; hc 3.2mm, 1.5mm c), Group 4 (cc 19mm; hc 4mm, 1.5mm c), Group 5 (cc 19mm; hc 4mm, 0.4mm c), Group 6 (cc 19mm; hc 3.2mm, 1.5mm c), Group 7 (cc 19mm; hc 3.2mm, 0.4mm c), Group 8 (cc 26mm; hc 4mm, 1.5mm c), Group 9 ( cc 26mm; hc 4mm, 0.4mm c) Group 10 (cc 26mm; hc 3.2mm, 1.5mm c) and Group 11 (cc 26mm; hc 3.2mm, 0.4mm and c). All specimens were subjected to compression test in a universal testing machine with 5000N load cell and constant speed of 0.5 mm / min. Data were analyzed by ANOVA statistical analysis three criteria, followed by Tukey test, with significance level was 5% (p <0.05). a significant difference in the decrease of resistance to compression with increasing length of the cantilever, a significant increase in resistance groups with height greater cantilevers was observed. It was concluded smaller length and greater height of cantielver, the greater the resistance. Already the connector thickness influenced the resistance, but without uniformity(AU)

Sistema CAD/CAM: uma alternativa para infraestruturas metálicas fundidas para próteses totais fixas implantossuportadas / The CAD/CAM system: an alternative to cast metal frameworks for complete fixed dental implant-supported prosthesis

Este trabalho relata um caso clínico do uso do sistema CAD/CAM para confecção da infraestrutura metálica. Um paciente de 57 anos de idade apresentava-se com uma prótese total metalocerâmica superior de longa data e próteses mandibulares bilaterais sobre dois implantes cada, afetados pela peri-implantite. O planejamento incluiu a remoção dos implantes afetados e a colocação de quarto novos implantes entre os forâmenes mentonianos, mas sem carregamento imediato em função da atividade parafuncional do paciente. A infraestrutura metálica foi fresada a partir de uma bolacha de CoCr em dez minutos. Cada cantiléver apresentou extensão de 20 mm. A adaptação passiva da prótese mandibular definitiva confirmou as possibilidades e benefícios da tecnologia CAD/CAM para próteses totais fixas implantossuportadas.

This paper reports a clinical case where a CAD/CAM system was used to fabricate a metallic framework. A 57 years-old patient presented with an old tooth-supported fused-to-metal prosthesis in the maxilla and bilateral mandibular implant-supported prostheses (two implants each) affected by peri-implantitis. The treatment planning included removal of infected implants and placement of four new dental implants between mental foramina, but with no immediate loading due to the patient´s parafunctional activities. The metallic infra-structure was milled from a CoCr disk in ten minutes. Each cantilever had a 20 mm-length. The passive fit of the definitive mandibular prosthesis was deemed excellent and confirmed the possibilities and benefi ts of the CAD/CAM technology for complete fixed implant-supported prostheses.

Reabilitação de maxila em carga imediata utilizando técnica guiada flapless, baseada em planejamento virtual pré-cirúrgico: relato de caso clínico / Rehabilitation of the maxilla with computer-assisted flapless surgery according to virtual preoperative planning: A case report

A técnica da cirurgia guiada, associada à tecnologia CAD/CAM, auxilia na busca de precisão na instalação de implantes osseointegráveis, pois segue um planejamento virtual que permite a visualização em software da relação da necessidade protética com a quantidade óssea disponível. Objetivo: o objetivo desse trabalho é relatar um caso de reabilitação de arcada superior com utilização do sistema NeoGuide (Neodent, Curitiba/PR), com técnica guiada flapless em carga imediata. Métodos: após o preparo pré-tomográfico e o planejamento virtual, foram instalados oito implantes Titamax EX cone-morse (Neodent) com a utilização de um guia cirúrgico prototipado. Após a instalação dos implantes, foi realizado exame radiográfico panorâmico e tomografia computadorizada. Em seguida, foi instalada uma prótese fixa implantossuportada. Conclusão: a utilização de técnica guiada flapless em carga imediata mostrou-se um recurso valioso no tratamento de reabilitações de arcadas superiores edêntulas, com redução do tempo cirúrgico e diminuição dos sintomas pós-operatórios, como dor, edema e inflamação.

Computer-guided surgery combined with CAD/CAM technology is a useful technique for placement of osseointegrated dental implants with utmost accuracy, since it employs virtual planning technology which allows visualization by a computer software of the relationship between one’s prosthetic needs and the amount of bone available. Objective: The aim of this studywas to report a case of maxillary rehabilitation with the use of the Neoguide system (Neodent®,Curitiba, Brazil), with the aid of computer-guided flapless technique and immediate loading. Methods: after pre tomographic preparation and virtual planning, eight Titamax EX Morse taperimplants (Neodent®, Curitiba, Brazil) were placed using a prototyped surgical guide. After implantplacement, panoramic radiographs and CT scans were performed. Subsequently, a fixed implant supported denture was installed. Conclusion: The use of computer-guided flapless surgery with immediate loading proved a valuable resource in maxillary rehabilitation, with reduced surgical time and decreased post-operative symptoms such as pain, swelling and inflammation.

Flexural strengths of implant-supported zirconia based bridges in posterior regions

PURPOSE: Impact forces in implant supported FDP (fixed dental prosthesis) are higher than that of tooth supported FDPs and the compositions used in frameworks also has a paramount role for biomechanical reasons. The aim of this study was to evaluate the flexural strength of two different zirconia frameworks. MATERIALS AND METHODS: Two implant abutments with 3.8 mm and 4.5 mm platform were used as premolar and molar. They were mounted vertically in an acrylic resin block. A model with steel retainers and removable abutments was fabricated by milling machine; and 10 FDP frameworks were fabricated for each Biodenta and Cercon systems. All samples were thermo-cycled for 2000 times in 5-55degrees C temperature and embedded in 37degrees C artificial saliva for one week. The flexural test was done by a rod with 2 mm ending diameter which was applied to the multi-electromechanical machine. The force was inserted until observing fracture. The collected data were analyzed with SPSS software ver.15, using Weibull modulus and independent t-test with the level of significance at alpha=.05. RESULTS: The mean load bearing capacity values were higher in Biodenta but with no significant differences (P>.05). The Biodenta frameworks showed higher load bearing capacity (F0=1700) than Cercon frameworks (F0=1520) but the reliability (m) was higher in Cercon (m=7.5). CONCLUSION: There was no significant difference between flexural strengths of both zirconia based framework systems; and both Biodenta and Cercon systems are capable to withstand biting force (even parafunctions) in posterior implant-supported bridges with no significant differences.

Comparação do desajuste vertical de infraestruturas metálicas sobre implantes: fundida versus fresada / Comparison of vertical misfit between cast and CNC-milled frameworks for implant-supported prostheses

A adaptação passiva da infraestrutura da prótese sobreimplantes é um dos parâmetros mecânicos que podem interferir na longevidade das próteses. Várias complicações no tratamento com implantes osseointegrados podem ser causadas por deficiência na adaptação das infraestruturas protéticas, podendo ser agravadas pela ausência de ligamento periodontal. O objetivo deste trabalho foi comparar a desadaptação de infraestruturas metálicas em monobloco parafusadas sobreimplante, confeccionadas pelo sistema de fundição por cera perdida e fresadas por sistema CAD/CAM. Sobre um modelo mestre de alumínio foram instalados quatro análogos de minipilares. Sobre estes foram confeccionadas duas barras metálicas: uma fundida em Co-Cr e outra fresada. O desajuste vertical na interface barra/análogos foi mensurado utilizando-se um microscópio comparador. Foi calculada a média de desadaptação em cada um dos pilares (45, 43, 33 e 35) e a média final de desadaptação de cada uma das barras. Na barra metálica fresada observou-se redução nos valores da desadaptação vertical em todos os pilares. A barra metálica fundida mostrou uma desadaptação vertical média (108,6 µm) aproximadamente dez vezes maior do que a barra metálica fresada (9,6 µm).

Passive fit of an implant framework is one of the mechanical parameters that can affect treatment longevity. Several complications in dental implant treatment may be due to misfit of metallic frameworks and can be aggravated by the absence of periodontal ligament. The objective of this study is to compare the misfit of a metallic, one-piece cast and CNC-milled implant frameworks. Four implant analogues were placed in a aluminum master model to receive conical abutments. A Co-Cr alloy was used in both groups. Vertical misfits at implant-framework interface were measured with an optical microscope. Mean misft levels were registered at implant positions 45, 43, 33, and 35, as well as for the overall sample. Individual misfit levels were reduced in CNC-milled frameworks. Cast frameworks showed a mean vertical misfit level (108.6 micrometers) almost 10 times higher than in the milled frameworks (9.6 micrometers).

Análise por elementos finitos e caso clínico do uso de retenções metálicas para diminuir o risco de descolamento de dentes artificiais em próteses do tipo protocolo / Finite element analysis and case study on the use of metal retentive projections to reduce dettachment of artificial teeth in total fixed, implant-supported restorations

Os dentes artificiais de próteses totais têm alto índice de descolamento e/ou fratura. Embora existam diversas técnicas para melhorar o nível de adesão do dente a base acrílica, é possível a utilização de retenções metálicas com esse fim, embora não existam estudos sobre a eficácia dessas retenções. Foi realizada uma análise, através do método de elementos finitos, de próteses totais fixas implantossuportadas, comparando a pressão trativa na superfície dos dentes artificias de próteses com retenções metálicas nos dentes ou na base da prótese, quando comparados com uma prótese sem nenhuma retenção adicional. A análise considerou diferentes padrões de carga mastigatória. Os resultados demonstraram que a confecção de retenções metálicas na infraestrutura da base diminuiu significativamente a pressão de descolamento sobre a superfície do dente artificial, entretanto, as retenções localizadas nos dentes foram mais eficientes na diminuição da pressão do que as retenções na base acrílica. Um caso clínico foi colocado para demonstrar a confecção das retenções. O estudo concluiu que a utilização de retenções metálicas é benéfica para diminuir a pressão trativa sobre os dentes artificiais, mas que a posição das retenções também é importante. Sempre que possível, essas devem ser confeccionadas internamente aos dentes artificiais.

Artificial teeth used for complete dentures have a high rate of detachment and/or fracture. Although there are several techniques to improve adhesion of acrylic tooth, it is possible to use metal retentions for this purpose, although no studies testing its effectiveness exist. A finite element method was used for a total fixed implant-supported prosthesis to investigate tension on the surface of artificial teeth, with metal retentions on the teeth or the acrylic base, compared with prosthesis without any additional retention. The analysis considered different patterns of masticatory load. It was demonstrated that the use of retentive features in the infra-structure significantly reduces the pressure on the surface of artificial teeth; however, retentions located inside the teeth were more efficient in reducing the pressure than retentions located in the acrylic base. A case study demonstrates the use of such retentions. The use of metal retention is beneficial to reduce tension on artificial teeth, but the position of the retention is also important. Whenever possible, they must be made internally to the artificial tooth.

Maxillary cement retained implant supported monolithic zirconia prosthesis in a full mouth rehabilitation: a clinical report

This clinical report presents the reconstruction of a maxillary arch with a cement retained implant supported fixed prosthesis using a monolithic zirconia generated by CAD/CAM system on eight osseointegrated implants. The prosthesis was copy milled from an interim prosthesis minimizing occlusal adjustments on the definitive prosthesis at the time of delivery. Monolithic zirconia provides high esthetics and reduces the number of metal alloys used in the oral cavity.

Prótese total implantossuportada removível na reabilitação de maxila desdentada / Implant-supported overdenture for the rehabilitation of the edentulous maxilla: a case report

Diferentes desenhos de próteses totais implantossuportadas ou implantorretidas estão disponíveis para a reabilitação da maxila desdentada. Embora a preferência do paciente normalmente seja por uma reabilitação fixa, existem indicações claras onde a prótese removível é a mais recomendada. Muitos são os aspectos a serem considerados durante o planejamento buscando a decisão entre a prótese fixa ou removível. Portanto, o objetivo deste artigo foi apresentar e discutir os fatores clínicos presentes do desdentado superior que determinam a escolha do tipo de prótese, além de relatar um caso clínico de restauração de maxila desdentada. Um paciente usuário de prótese parcial removível superior apresentou-se com indicação de extração dos dentes remanescentes. Implantes imediatos e prótese total fixa provisória implantossuportada com carga imediata foram instalados. Após estabilização dos tecidos duro e mole, foram considerados aspectos como suporte labial, capacidade de higienização do paciente, entre outros, para eleição do tipo de prótese definitiva. Optou-se, então, pelo desenho final de uma prótese total implantossuportada removível, utilizando barra fresada parafusada com sistema de encaixes MK1.

Different designs of implant-supported or implant-retained prostheses are available for the rehabilitation of the edentulous maxilla. Although the patient's preference is usually for a fixed rehabilitation, there are clear indications where the removable prosthesis is the best option. There are many aspects on treatment planning to choose between a fixed or removable prosthesis. Therefore, the aim of this study is to present and discuss clinical factors that determine the choice of prosthesis, as well as to report a clinical case restoring an edentulous maxilla. A patient wearing an upper removable partial denture presented with hopeless teeth. Immediate implants were placed and restored with a full-arch provisional fixed implant-supported prosthesis. After stabilization of hard and soft tissues, factors such as lip support, oral hygiene levels, and other features were considered for the final restoration. Then, the final design included a removable implant-supported prosthesis over a milled bar and MK1 attachments.

Implantes dentários na substituição de PPRs com nivelamento do plano oclusal: relato de dois casos / Dental implants in replacement of partial denture with occlusal plan leveling: two case reports

Introdução: o uso de implantes osseointegrados na reabilitação de paciente parcialmente edêntulos é, atualmente, uma realidade que proporciona maior conforto àqueles que usam próteses removíveis, devido à substituição dessas por próteses fixas. Nos casos de reabilitação bucal, o plano oclusal precisa ser restabelecido para favorecer a saúde, a função e a estética. Objetivo: o objetivo deste trabalho é relatar dois casos clínicos onde a reabilitação bucal foi realizada em pacientes parcialmente edêntulos, usuários de próteses parciais removíveis (PPRs). Relato dos casos: os casos foram planejados com modelos de estudo, montados em articulador semiajustável (ASA) e feito enceramento diagnóstico. A seguir, foram feitas cirurgias para colocação de implantes dentários e restaurações dos dentes remanescentes. Após o período de osseointegração, próteses parciais fixas implantossuportadas foram confeccionadas e instaladas com adequação do plano oclusal. O controle clínico, aos 24 e 36 meses, dos casos demonstra saúde dos tecidos periodontais e peri-implantares, estabilidade das próteses e satisfação dos pacientes. Conclusão: pode-se concluir, de acordo com os resultados obtidos, que a substituição de PPRs por implantes dentários pode ser realizada com sucesso, mediante planejamento cirúrgico-protético adequado e utilização criteriosa dos fundamentos de oclusão.

Introduction: The use of osseointegrated implants in the rehabilitation of partially edentulous patients is currently a reality that provide greater comfort for individuals with removable partial dentures (RPDs), due to the replacement of these ones by fixed dentures. In cases of oral rehabilitation, the occlusal plane needs to be reestablished to promote health, function and aesthetics. Objectives: The objective of this study is to report two cases where the oral rehabilitation was carried out in partially edentulous patients that used removable partial dentures. Case reports: The cases were planned through study cast models assembled in semi-adjustable articulator and diagnosis waxing. Then surgeries were done for placement of dental implants and restoration of the remaining teeth. After the osseointegration period, implant-supported fixed partial dentures were installed and the occlusal plane adequate. The 24 and 36 months follow-up of the cases demonstrate the health of the peri-implant and periodontal tissues, stability of prostheses and patient satisfaction. Conclusion: We can conclude, according to the results obtained, that RPDs replacement by dental implants can be successfully performed through appropriate surgical-prosthetic planning and judicious use of the occlusion fundamentals.

Porcelain application and simulation of firing cycle: effect on marginal misfit of implant-supported frameworks

Aim: Success of implant-supported prostheses is related to the frameworks’ passive fit, henceinaccuracies can generate stress, leading to bone resorption and rehabilitation failure. This study evaluated misfit levels of implant-supported frameworks after different coverage treatments.Methods: Twenty commercially pure titanium (CP Ti) frameworks were manufactured with 5Branemark type multi-unit abutments. Frameworks were distributed in two groups as follows: G1- porcelain application (n=10); G2 - porcelain firing cycle simulation (n=10). Using a traveling microscope, marginal misfit was measured before and after undertaking the techniques, following the single-screw test protocol. All data were submitted to ANOVA and Tukey’s test (p<0.05).Results: Initial marginal misfit values were not significantly different, but both groups presented significantly higher misfit values after treatment: G1: 233.99 ìm (p=0.0003); G2: 119.75 ìm(p<0.0001). In addition, G1 presented higher misfit than G2 (p<0.0001). Conclusions: Porcelain application promoted significantly higher increase of misfit, which indicates that such procedure should be considered on misfit analysis of implant-supported prostheses.

A importância do planejamento protético em Implantodontia / The importance of prosthetic treatment planning on implant dentistry: a case report

Em reabilitações orais extensas devemos buscar uma visão multidisciplinar durante o diagnóstico, prognóstico e plano de tratamento a fim de proporcionar um resultado que tenha boa previsibilidade e atenda as expectativas estéticas e funcionais do paciente que vai se submeter ao tratamento. Para tal, o correto planejamento é de fundamental importância. Este caso clínico apresenta um paciente com 58 anos, diabético controlado, com infarto de miocárdio há mais de seis meses, apresentando-se bastante insatisfeito com o trabalho que havia sido finalizado há pouco tempo. Observamos uma severa alteração do plano oclusal, próteses sobreimplantes com falta de adaptação, ausência de intermediários protéticos, comprometimento gengival nas regiões peri-implantares, a prótese com cantiléver distal no hemiarco superior direito com invasão do espaço biológico e recidiva de cárie nos pré-molares, grande comprometimento estético e severo comprometimento psicológico. O plano de tratamento incluía moldagem, modelo de estudo, jig, chapa de prova com registro em cera, montagem em ASA, em RC, enceramento diagnóstico, raspagem e polimento coronário, instalação de componentes protéticos do tipo pilar cônico, regulares e angulados (Neodent), provisórios sobreimplante, cirurgia de levantamento de seio maxilar direito e instalação de implantes (Neodent), núcleo metálico fundido em ouro, moldagens com casquetes, moldagens de transferência, pontos de solda e restaurações finais em metalocerâmica. Foi possível concluir que em um trabalho de reabilitação oral, o planejamento é de fundamental importância para que obtenhamos um prognóstico favorável e uma condição clínica ótima para a realização do trabalho, proporcionando a satisfação do paciente.

In complex oral rehabilitation work, we must seek a multidisciplinary vision for the diagnosis, prognosis, and treatment, providing a result that has good predictability and meets the aesthetic and functional expectations of the patient. For this, a sound treatment planning is important. This case presents a 58 years-old patient, metabolically controlled for diabetes mellitus, with myocardial infarction of more than six months, being quite dissatisfied with the a recent work. We noticed severe change of the occlusal plane, lack of fit at the implant-supported prosthesis, peri-implant inflammation, and impingement of biological width at the prosthesis with distal cantilever on the upper right quadrant; biological recurrence of caries in premolars, great aesthetic and severe psychological impairment. The treatment planning included confection of study models study and wax rims for centric relation registration in a semi-adjustable articulator, scaling and polishing at the coronal level, abutment installation, surgical removal of the right maxillary sinus and implant placement, as well as traditional procedures for definitive ceramic restorations. It can be concluded that treatment planning is very important to achieve a favorable prognosis and patient satisfaction.

Electromyographic evaluation of mastication and swallowing in elderly individuals with mandibular fixed implant-supported prostheses

This study evaluated the effect of implant-supported oral rehabilitation in the mandible on the electromyographic activity during mastication and swallowing in edentulous elderly individuals. Fifteen patients aged more than 60 years were evaluated, being 10 females and 5 males. All patients were edentulous, wore removable complete dentures on both dental arches, and had the mandibular dentures replaced by implant-supported prostheses. All patients were submitted to electromyographic evaluation of the masseter, superior orbicularis oris muscles, and the submental muscles, before surgery and 3, 6 and 18 months postoperatively, using foods of different textures. The results obtained at the different periods were analyzed statistically by Kruskal-Wallis non-parametric test. Statistical analysis showed that only the masseter muscle had a significant loss in electromyographic activity (p<0.001), with a tendency of similar response for the submental muscles. Moreover, there was an increase in the activity of the orbicularis oris muscle during rubber chewing after treatment, yet without statistically significant difference. Mandibular fixed implant-supported prostheses in elderly individuals revealed a decrease in electromyographic amplitude for the masseter muscles during swallowing, which may indicate adaptation to new conditions of stability provided by fixation of the complete denture in the mandibular arch.

Platform switching: avaliação biomecânica por meio do método de elementos finitos tridimensional / Platform switching: biomechanical evaluation using three-dimensional finite element analysis

Introdução e Justificativa. No tratamento com implantes osseointegrados, o tecido ósseo peri-implantar sofre um processo de aposição e reabsorção, durante o primeiro ano após a restauração protética. Tem sido relatado que a platform switching reduz a remodelação óssea esperada, muito embora os mecanismos responsáveis por este processo não estejam claramente elucidados. Objetivo. O objetivo deste trabalho foi avaliar a distribuição de tensões no tecido ósseo peri-implantar, nos implantes e componente protéticos de coroa metalocerâmica implantossuportada, utilizando o conceito de platform switching e comparando-o com uma conexão regular abutment-implante, por meio do método de elementos finitos tridimensional (MEF-3D). Material e métodos. Dois modelos 3D reproduziram uma conexão regular entre abutment-implante com componentes de mesmo diâmetro (grupo Plataforma Regular - PR) e uma conexão com o conceito de platform switching (grupo Platform Switching - PS). Um implante regular (plataforma protética de 4.1mm) e um implante largo (plataforma protética de 5.0mm) foram utilizados para representar PR e PS, respectivamente, nos quais um componente protético regular de 4.1mm foi conectado para simular a coroa protética. Uma carga de 100N foi aplicada utilizando-se o programa ANSYS. Resultados. PS diminuiu a concentração de tensões no implante quando comparado com PR, alterando a distribuição das tensões na plataforma protética, o que resultou em diminuição das tensões no parafuso e tecido ósseo e aumento das tensões na coroa. Conclusões. Platform switching reduziu as tensões no tecido ósseo peri-implantar, o que pode resultar em uma diminuição da reabsorção óssea marginal. A utilização de componentes protéticos de menor diâmetro que a plataforma protética do implante diminuiu a concentração das tensões nos implantes e no parafuso, podendo resultar em uma diminuição das complicações nas próteses implantossuportadas parafusadas.

Statement of problem. After implant insertion and loading, crestal bone usually undergoes remodeling and resorption during the first year following prosthetic restoration. It has been reported that the platform switching seems to reduce or eliminate the expected postrestoration crestal bone remodeling, although the mechanisms responsible for this process are not yet clearly drawn. Purpose. The objective of this study was to evaluate the stress distribution in periimplant bone tissue, implants and prosthetic components of single crown implantssupported with the use of platform switching concept, using three-dimensional Finite Element Analysis (3D- FEA). Material and methods. Two 3D finite element models reproduced a external hexagonal implant system with peri-implant bone tissue, in which a regular matching diameter connection of abutment-implant (Regular Platform group - RPG) and a platform switching connection (Platform Switching group - PSG) were simulated. A regular implant (prosthetic platform of 4.1mm) and a wide implant (prosthetic platform of 5.0mm) were used to represent the RPG and PSG, respectively, in which a regular prosthetic component of 4.1mm was connected to represent the crown. A load of 100N was applied on the models using ANSYS software. Results. PSG diminished the stress concentration at the implant when compared to RPG by altering the stress distribution at the prosthetic platform of the implant, which results in a decrease of stress into the screw and supporting bone and an increase of stress in the crown. Conclusions. Platform switching improved biomechanically the stress distribution in peri-implant bone tissue of implant system, which might result in a reduced marginal bone loss. The use of mismatching prosthetic components in relation to the implant prosthetic platform diameter seems to decrease stress concentration at implant and screw, which might represent less clinical complications.

Implant-Supported Fixed Prostheses for the rehabilitation of distal free end in periodontally compromised dentitions Number of fixtures affecting bone tissue change / 대한치주과학회지

Number of fixtures supporting prosthesis for rehabilitation of partial edentulism in distal area is an important factor in distal area to the bone tissue response around dental implant. Optimal number and optimal positioning of dental implant has leaded to the stable condition of bone tissue and successful long-term treatment outcome. This clinical and radiographic study was performed to document and evaluate the short-term result of occlusal rehabilitation by means of implant-supported fixed prostheses (ISPs) especially for partial edentulism in distal area in patients treated for advanced periodontal disease and to verify the number of fixture affecting the bone tissue response. A total of 30 consecutive patients referred because of advanced periodontal disease were included. Before the implant therapy was initiated, periodontal treatment was performed and the outcome evaluated during at least a 6-month period. An individual maintenance care program was designed for each patient. All 75 implants were placed using a 2-stage surgical approach. The patients were divided into 2 groups, in one of which two fixtures were placed and in the other of which three fixtures were placed with tripodal geometry. Following installation of the ISPs, all patients underwent a baseline examination including evaluation of i) oral hygiene, and ii) periodontal/ peri-implant conditions, and iii) radiographs. These examinations were repeated annually during the 1 or 2-year observation period. The results were as follows: 1.No single implant was lost during the observation follow-up period. 1.The percentage of plaque harboring surfaces and bleeding units upon probing were found to be low (<10%), and no soft tissue complications were recorded. 1.Two-fixture group showed bone destruction ranged from 0.0mm to 1.5mm and the mean was 0.31mm. Three-fixture group showed more bone destruction of 0.51mm. There was no statistically difference between two groups. These results suggested that the factor for success is not the number of fixture but the strict maintenance of peri-implant tissue health and initial stability of fixture.