Estudio correlacional de complicaciones técnicas, biológicas, estéticas y nivel de satisfacción en tratamientos realizados en la Cátedra de Prótesis de Coronas y Puentes II de la Facultad de Odontología de la Universidad Nacional de Asunción

El objetivofue determinar la asociación correlacional que pudiera presentarse entre las complicaciones técnicas, biológicas y estéticas y el nivel de satisfacción de los tratamientos realizados en la Cátedra de Prótesis de Coronas y Puentes II de la Facultad de Odontología de la UNA en el 2019. Este fue un estudio observacional descriptivo, analítico, de corte transverso. Se incluyeron pacientes que recibieron tratamientos del 2016 al 2018. Acudieron 59 pacientes para la evaluación clínica y aplicación del cuestionario. Se analizaron los datos según número de tratamientos encontrados en cada sujeto, por lo que se calcularon los resultados según 119 tratamientos. Las complicaciones biológicas pulpares fueron la sensibilidad o molestia al frio o al calor en los pilares en un 20.1%. Se encontró asociación muy significativa de las complicaciones biológicas pulpares (p>001) con estado civil, complicaciones biológicas periodontales, complicaciones estéticas cervicales. Las complicaciones biológicas periodontales fueron en mayor frecuencia la gingivitis alrededor de la restauración en un 40,4%. El nivel de satisfacción con el tratamiento recibido se presentó favorable en un 89,1% y asociación muy significativa (p>001) con grado de instrucción y significativa (p>005) con estado civil.Se encontró asociación muy significativa de las complicaciones estéticas cervicales, las complicaciones estéticas de forma y significativa de las complicaciones biológicas periodontales con el nivel de satisfacción.

The objective was to determine the correlational association that could occur between technical, biological and esthetic complications and level of satisfaction in the treatments performed in the Department of Crown and Bridge Prosthodontics II of the Faculty of Dentistry of the National University of Asuncion in 2019. This was a descriptive, analytical, cross-sectional, observational study. Patients who received treatments from 2016 to 2018 were included. Fifty-nine patients attended for clinical evaluation and application of the questionnaire. The data were analyzed according to the number of treatments found in each subject, by which the results were calculated according to 119 treatments. Pulpal biological complications were sensitivity or discomfort to cold or heat in 20.1% of the abutments. A highly significant association was found between pulpal biological complications (p>001) and marital status, periodontal biological complications and cervical esthetic complications. The most frequent periodontal biological complications were gingivitis around the restoration (40.4%). The level of satisfaction with the treatment received was favorable in 89.1% and there was a very significant association (p>001) with educational level and significant (p>005) with marital status. A highly significant association was found between cervical esthetic complications, esthetic complications of shape and periodontal biological complications and the level of satisfaction.

Effectiveness of implant-supported fixed partial denture in patients with history of periodontitis: A systematic review and meta-analysis.

AIM: This systematic review investigates the effectiveness of implant-supported fixed partial denture (IS-FPD) in patients with history of periodontitis (HP) vs. patients with no history of periodontitis (NHP). METHODS: A literature search was performed on different databases on May 2020. Prospective and retrospective studies assessing survival (primary outcome), success and biological/mechanical complications of IS-FPDs in HP vs. NHP patients at ≥1 year after implant loading were evaluated. Meta-analyses were conducted by estimating hazard ratio (HR), risk ratio (RR) and standardized mean differences (SMD) with 95% confidence intervals (CI) using random effect models. RESULTS: Of the initially identified 4096 articles, 349 underwent a full-text evaluation. Finally, 17 were included. Pooled data analyses showed that overall implant survival was significantly higher in the NHP than the HP group (HR = 2.06; 95% CI = 1.37-3.09; I2  = 0%). This difference was noted when follow-up ≥5 years. The risk of peri-implantitis was higher in HP than NHP patients (RR = 3.3; 95% CI = 1.31-8.3; I2  = 0%), whereas the mean marginal bone level change over time was not different between the groups (SMD = -0.16 mm; 95% CI = -1.04-0.73; I2  = 98%). CONCLUSIONS: In partially edentulous patients receiving IS-FPDs, a history of periodontitis is associated with poorer survival rate and higher risk of peri-implantitis during a 5-10 years period after implant loading.

Peri-Implant Behavior of Tissue Level Dental Implants with a Convergent Neck.

INTRODUCTION: The aim of this retrospective study was to analyze the radiographic peri-implant bone loss of bone level implants and tissue level implants with a convergent neck in screw-retained single crowns and in screw-retained fixed partial prostheses, after two years of functional loading. MATERIALS AND METHODS: The sample was divided into two groups according to their type: Group I: supracrestal implants with convergent transmucosal neck; Group II: crestal implants. In each group we distinguish two subgroups according to the type of prosthetic restoration: single crowns and a three-piece fixed partial prosthesis on two implants. To quantify bone loss, parallelized periapical radiographs were analyzed at the time of implant placement and after two years of functional load. RESULTS: A total of 120 implants were placed in 53 patients. After statistical analysis it was observed that for each type of implant bone loss was 0.97 ± 0.91 mm for bone level and 0.31 ± 0.48 mm for tissue level. No significant differences were found regarding the type of prosthesis and the location (maxilla or mandible) of the implants. CONCLUSIONS: Tissue level implants with a convergent transepithelial neck exhibit less peri-implant bone loss than bone level implants regardless of the type of prosthesis.

Survival and complication rates of tooth-implant versus freestanding implant supporting fixed partial prosthesis: a systematic review and meta-analysis.

PURPOSE: This systematic review was performed to compare tooth, implant and prosthesis failures and biological and technical complications in toothimplant vs freestanding implant supported fixed partial prostheses, in order to evaluate the effectiveness and predictability in combining teeth and implants in the same fixed partial prosthesis. STUDY SELECTION: A comprehensive and systematic literature research was conducted, according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement, to identify human trials, with a minimum sample size of 10 patients, comparing tooth-implant to freestanding implant supported fixed partial prostheses. Four groups of meta-analyses were performed based on the patients treated with toothimplant vs freestanding implant-supported fixed partial prostheses: abutment failures, biological and mechanical complications, prosthesis failures, and prosthetic (technical) complications. RESULTS: The search yielded 749 records, after removal of duplicates. Based on the title assessment, the abstracts reading and the full-texts evaluation, 8 articles, published between 1999 and 2013, fulfilled the inclusion criteria and were included in the meta-analysis. The studies included were: 4 controlled clinical trials, 2 prospective and 2 retrospective cohort studies. The meta-analysis revealed no significant difference between tooth-implant and implant-implant supported fixed in the number of abutment (implant or tooth) failures, biological complications, prosthesis lost, and prosthetic complications. CONCLUSIONS: Within the limitations of the present systematic review, although the freestanding implant supported fixed partial prosthesis remains the first choice, joining teeth and implants to support fixed prosthesis in partially edentulous patients becomes a valid alternative with an acceptable success rate.

The biological width around implant.

PURPOSE: The concept of biological width has been proposed and widely used in oral implantation. This review aimed to summarize the biological width around implant in detail. STUDY SELECTION: An electronic search of the literature prior to March 2019 was performed to identify all articles related to biological width in periimplant soft tissue. The search was conducted in the MEDLINE (National Library of Medicine) database accessed through PubMed with no date restriction. The following main keywords were used: "implant", "biological width", "soft tissue", "junctional epithelium", "peri-implant epithelium", "connective tissue", "gingiva", "mucosa" (connecting multiple keywords with AND, OR). RESULTS: The identified researches focused on several aspects related to biological width in oral implantation, namely the concept, formation, remodeling, dimension, structure and function. CONCLUSIONS: Based on of the reviewed literature, the concept, formation, remodeling, structure, dimension, and functional significances of periimplant biological width are explored in this narrative review. The formation of biological width around implant is a complex process after several weeks of healing. The biological width around implant is a 3-4mm distance from the top of the peri-implant mucosa to the first bone-to-implant contact or the stabilized top of the adjacent bone, consisting of sulcular epithelium, junctional epithelium and fibrous connective tissue between the epithelium and the first bone-to-implant contact or the stabilized top of the adjacent bone. The biological width forms a biological barrier against the bacteria, influences the remodeling of soft and hard tissue around implant and has implications for clinical aspects of dental implantation.

Comparison of the Crestal Bone Loss Between Implant-Supported Prosthesis With Sinus Augmentation and Distal Cantilevered Implant-Supported Prosthesis Without Sinus Augmentation.

This study aimed to compare the crestal bone loss between a 2-implant-supported, noncantilevered 3-unit fixed partial prosthesis (TUFPP) with sinus augmentation and a 2-implant-supported, distal cantilevered TUFPP without sinus augmentation in the posterior maxilla having insufficient crestal bone. The study subjects were enrolled in 2 groups. Group 1 included patients with 2 implants: an anterior implant placed in the native bone and a posterior implant inserted with simultaneous sinus augmentation using a xenogenic bone graft to support a TUFPP. Group 2 included patients with 2 implants inserted in the native bone to support a distal cantilevered TUFPP. The crestal bone levels at the distal and mesial aspects of each implant were measured at baseline and 6-, 12-, and 24-month follow-up controls on panoramic radiographs. Fifty-two patients and 104 implants were included. There was a significant difference in distal crestal bone loss between anterior and posterior implants in group 1 at 6 months (P < .05) but not at 12 and 24 months (P > .05). Distal crestal bone loss was significantly increased in group 1 posterior implants compared to the group 2 posterior implants at 6 months (P < .05). There was no significant difference in mesial bone loss between the anterior and posterior implants in both groups at all follow-up controls (P > .05). There was also no significant mesial crestal bone loss in relation to the anterior and posterior implants of both groups at all follow-up controls (P > .05). Noncantilevered 2-implant-supported TUFPP with sinus augmentation may have similar medium-term crestal bone loss when compared to cantilevered 2-implant-supported TUFPP without sinus augmentation. Further prospective studies should be designed to compare the performance of the 2-implant-supported cantilevered TUFPP and 2-implant-supported TUFPP with sinus augmentation.

Extension implants in the atrophic posterior maxilla: 1-year results of a retrospective case-series.

BACKGROUND/PURPOSE: Blade implants account for one of the most debated dental implants design in scientific literature. They have been reconsidered by clinicians since their re-classification by Food and Drug Administration in 2014. MATERIALS AND METHODS: The present study aimed to evaluate the outcome of newly manufactured extension implants in the treatment of moderate atrophic posterior maxillae. All the patients enrolled in the present retrospective case series study showed a moderate bone atrophy in the posterior maxilla with a maximum residual height ranging between 4 mm and 8 mm. Implants were inserted with the aid of an electro-magnetic device, and then they covered with screws and left healing. Three months after, implants were exposed and loaded. RESULTS: Difference between the marginal bone level at the 3-month evaluation (5.57 ±â€¯0.67 mm) and that at baseline (5.67 ±â€¯0.55 mm) appeared to be not significant (p-value = 0.63). At the 12-month evaluation, the marginal bone level (4.95 ±â€¯0.45 mm) underwent significant decrease respect to baseline value as proven by significant change at marginal bone level (-0.62 ±â€¯0.51 mm with a p-value = 0.01). CONCLUSION: The results of the present study suggested a positive 12-month outcome for extension implants in the rehabilitation of the moderate atrophic maxilla, without the need of extensive reconstructive surgeries and grafting procedures.

Stress distribution of three-unit fixed partial prostheses (conventional and pontic) supported by three or two implants: 3D finite element analysis of ductile materials.

In implantology, when financial or biological feasibility limitations appear, it is necessary to use prostheses with geometries that deviate from the conventional, with a pontic in the absence of an intermediate implant. The aim of this study was analyze and understand the general differences in the stresses generated in implants, components and infrastructures according to the configuration of the prosthesis over three or two implants. Thus, this paper analyzes the von Mises equivalent stresses (VMES) of ductile materials on their external surfaces. The experimental groups: Regular Splinted Conventional Group (RCG), which had conventional infrastructures on 3 regular-length Morse taper implants (4x11 mm); Regular Splinted Pontic Group (RPG), which had infrastructures with intermediate pontics on 2 regular-length Morse taper implants (4x11 mm). The simulations of the groups were created with Ansys Workbench 10.0 software. The results revealed that the RPG presented greater areas of possible fragility due to higher stress concentrations, for example, in the cervical area of the union between the implant and component the top platform of the abutment, as well as greater coverage of the stress by the cervical implant threads. The RPG infrastructure was also more affected by stresses in the connection areas between the prostheses and on the occlusal surface. There is an advantage to using prostheses supported by a greater number of implants (RCG) because this decreases the stress in the analyzed structures and consequently improves stress dissipation to the supporting bone, which would preserve the system.

Stress distribution on short implants with different designs: a photoelastic analysis.

Short dental implants have been used as an attempt to avoid bone grafts surgery, however there are few literature reports that evaluate changes to their design. Therefore, the aim of this study was to assess the effect of different short implant design on stress distribution through photoelastic analysis. Six external hexagon (5 × 5 mm) short dental implants with different design were used. Each group was treated with a single crown and a three element fixed partial dental prosthesis, resulting in a total of 12 photoelastic models. The assembling photoelastic model-implant-prosthesis was set in a circular polariscope where loads of 100N were applied on the occlusal surface with a Universal Test Machine (UTM). The tension fringes were photographed and later assessed qualitatively by a graphic software (Adobe Photoshop). Less high-intensity fringes were observed on the short implants with triangular threads, short external hexagon and flat apical profile. In conclusion, the macrodesign influenced the amount of stress distributed to the bone when short dental implants are placed.

Avaliação comparativa dos níveis de desajustes marginais de pilares UCLAS calcináveis assentados sobre a plataforma de implantes e sobre pilar cônico em próteses fixas implantosuportadas / Comparative assessment of the levels of marginal misfits UCLAS calcinable pillars seated on the platform and on implant abutment conical

Este trabalho objetivou avaliar os níveis de desajustes marginais de infraestruturas metálicas em próteses fixas assentadas sobre pilar cônico pré-fabricado (estheticone) e diretamente sobre o hexagonal do implante. Foram obtidas quatro amostras de infraestruturas de próteses fixas fundidas em liga de Níquel-Cromo assentadas sobre análogos de implantes regulares e sobre análogos do pilar cônico. As infraestruturas foram distribuídas em dois grupos (n=2) experimentais. Os desajustes marginais verticais (µm) foram avaliados com o emprego de um microscópio mensurador digital. Cada amostra recebeu quatro marcações diametralmente opostas (mesial, distal, vestibular e lingual) e foram avaliadas três vezes em cada uma dessas superfícies com o parafuso de fixação devidamente adaptado. Para a análise estatística foi utilizado o teste de U Mann Whitney na correlação dos valores das quatro faces diametralmente opostas (mesial, distal, vestibular e lingual) de ambos os grupos. Ainda, utilizou-se o teste Kruskal-Wallis para correlacionar os valores obtidos entre os pilares empregados. Os resultados mostraram que não houve diferença estatisticamente significante no desajuste marginal entre os grupos comparados. Concluiu-se que não houve diferença no desajuste marginal de infraestruturas metálicas de próteses sobre implantes fundidas com ligas de Ni-Cr com UCLA assentados sobre pilar estheticone ou diretamente sobre o hexágono de um implante de plataforma regular (AU).

The objective of this work was to evaluate the levels of marginal mismatches of metallic infrastructures on fixed prostheses seated on the following types of platforms: pre-fabricated conical pillar (estheticone), pillar UCLA, and directly on the hexagonal of the implant. Samples of infrastructures of fixed prostheses made of nickel-chrome alloy and seated on similar regular implants and on similar conical pillar were used. The infrastructures were distributed in two experimental groups (pillar estheticone and direct pillar on the platform). For the evaluation of vertical marginal mismatches (µm), each sample was seated on its platform and observed with the aid of a digital measuring microscope. Each sample received four marks, diametrically opposite to each other (mesial, distal, vestibular, and lingual) and all samples were evaluated three times in each surface with the fixation screw properly adapted. The averages of these evaluations were obtained using U Mann Whitney and Kruskal-Wallis statistical tests. The result of the U Mann Whitney test,did not show significant statistical difference while Kruskal-Wallis test showed difference between the estheticone pillar and the UCLA pillar. The estheticone pillar showed lower mismatches averages than the UCLA pillar and, no significant statistical difference was observed in the comparison with the hexagonal platform of the implant (AU).

Efeito de uma malha de nylon contendo sílica como reforço em próteses parciais fixas em resina composta indireta / Effect of a nylon mesh containing silica as reinforcement on fixed partial dentures in indirect composite resin

O presente estudo teve como objetivo avaliar as características mecânicas de próteses parciais fixas adesivas, confeccionadas em resina composta de uso indireto, reforçadas por uma malha de nylon. Para a confecção da matriz dos espécimes e estudo das tensões nas estruturas, foi realizada análise qualitativa pregressa análise de elementos finitos (FEA). A pesquisa in vitro simula uma prótese parcial fixa de três elementos com inserção entre os primeiros pré-molares e os primeiros molares superiores (n = 60; 10 por grupo). Três dos seis grupos passaram por ciclagem mecânica. Os grupos experimentais foram: G1-prótese fixa convencional; G2 - prótese convencional ciclada; G3 - prótese com reforço da malha posicionada na vertical; G4 ­ Prótese com reforço da malha posicionada na vertical ciclada; G5 ­ Prótese com reforço da malha posicionada na horizontal; G6 ­ Prótese com reforço da malha posicionada na horizontal ciclada.Todos os grupos passaram por ensaio de carga máxima a fratura (EMIC). Os resultados não apresentaram diferença estatística entre os grupos. Concluiu-se que a utilização da malha nylon proporcionou estabilidade, mesmo após a fratura da peça, pois as partes não se separam, além disso, os resultados obtidos in vitro puderam validar os dados in sílico(AU)

The present study aimed to evaluate the mechanical characteristics of adhesive fixed partial dentures, made from composite resin of indirect use, reinforced by a nylon mesh. A finite element analysis (FEA) was used to compile the specimen matrix and to study the stresses in the structures. In vitro research, simulated a fixed partial denture of three elements with insertion between the first premolars and the major maxillary molars (n = 60; 10 per group). Three of the six groups underwent mechanical cycling. The experimental groups were: G1 - conventional fixed prosthesis; G2 - conventional cyst prosthesis; G3 - prosthesis with reinforcement of the mesh positioned vertically; G4 - Prosthesis with reinforcement of the mesh positioned in the cycled vertical; G5 - Prosthetics with mesh reflux positioned horizontally; G6 - Prosthetics with mesh reinforcement positioned horizontally cycled. All groups underwent maximum fracture loading test (EMIC). The results do not present a statistic between the groups. It was concluded that the use of the nylon mesh provided stability, even after fracture of the part, as parts do not separate, besides, the results obtained in vitro could validate the data in silica(AU)

Three-Year Outcome of Fixed Partial Rehabilitations Supported by Implants Inserted with Flap or Flapless Surgical Techniques.

PURPOSE: The aim of this prospective clinical study was to evaluate the 3-year outcome of fixed partial prostheses supported by implants with immediate provisionalization without occlusal contacts inserted in predominantly soft bone with flap and flapless protocols. MATERIALS AND METHODS: Forty-one patients partially rehabilitated with 72 NobelSpeedy implants (51 maxillary; 21 mandibular) were consecutively included and treated with a flapless surgical protocol (n = 20 patients; 32 implants) and flapped surgical protocol (n = 21 patients; 40 implants). Primary outcome measure was implant survival; secondary outcome measures were marginal bone resorption (comparing the bone levels at 1 and 3 years with baseline) and the incidence of biological, mechanical, and esthetic complications. Survival was computed through life tables; descriptive statistics were applied to the remaining variables of interest. RESULTS: Eight patients with eight implants dropped out of the study. One implant failed in one patient (flapless group) giving an overall cumulative survival rate (CSR) of 98.6%. No failures were noted with the flapped protocol (CSR 100%), while for the implants placed with the flapless surgical technique, a 96.9% CSR was registered. The overall average marginal bone resorption at 3 years was 1.37 mm (SD = 0.94 mm), with 1.14 mm (SD = 0.49 mm) and 1.60 mm (SD = 1.22 mm) for the flap and flapless groups, respectively. Mechanical complications occurred in nine patients (n = 5 patients in the flapless group; n = 4 patients in the flap group). Implant infection was registered in three implants and three patients (flapless group), who exhibited inadequate oral hygiene levels. CONCLUSIONS: Partial edentulism rehabilitation through immediate provisionalization fixed prosthesis supported by dental implants inserted through flap or flapless surgical techniques in areas of predominantly soft bone was viable at 3 years of follow-up. The limitations and risks of the "free-hand" method in flapless surgery should be considered when planning implant-supported fixed prosthetic reconstructions.

Short implants in maxillary and mandibular rehabilitations: interim results (6 to 42 months) of a prospective study.

The aim of this single-cohort study was to evaluate clinical survival and success of partial rehabilitation supported by reduced-length implants in maxilla and mandible. Data from 53 short implants placed in 41 patients are presented. Before surgery mean residual bone height was 6.21 ± 1.05 mm in the upper jaw and 10.73 ± 1.63 mm in the mandible. None of the implants failed, and the cumulative survival rate was 100% at 1 year after prosthetic loading. Mean peri-implant bone loss was 0.69 ± 0.24 mm for maxillary implants and 0.73 ± 0.23 mm for mandibular implants, and there was no significant difference between the 2 jaws. No complications were recorded. Despite the limitations of this study concerning study design and sample size, short implants may be considered effective in supporting partial rehabilitation in both maxilla and mandible. More well-designed studies with a larger sample size and longer follow-up are needed to validate the use of short implants.

Frontal fixed prosthetic restoration in edentulous space modification.

This study case presents a 53 years old patient with severe aesthetic dysfunctions due to an ectopic maxillary canine associated with a frontal edentulous space. Orthodontic treatment proposition was refused by the patient. After canine extraction, metalo-ceramic fixed partial prosthesis successfully restored the aesthetic damage in the conditions of a non-gingival smile. Adapted abutment teeth preparations were made in order to provide necessary space for aesthetic alignment of artificial teeth in the pontic.

Associação de prótese fixa, implantes e estética periodontal para reabilitação de pacientes parcialmente edêntulos / Association of fixed partial prosthesis, dental implants, and periodontal aesthetic procedures for rehabilitation of partially edentulous patients

A doença periodontal é uma doença inflamatória crônica que resulta na destruição dos tecidos de suporte com consequente perda dental. A substituição dos dentes perdidos por restaurações implantossuportadas tem demonstrado ser um método de tratamento altamente previsível com bom prognóstico em longo prazo. Contudo, algumas sequelas da perda dentária inviabilizam a instalação de implantes osseointegrados em posição ideal, sendo, neste caso, necessários procedimentos regenerativos para tornar possível este tipo de reabilitação. Procedimentos menos invasivos, como próteses convencionais, surgem como uma opção terapêutica para reabilitação de casos em que não há estrutura óssea suficiente para implantes e não há aceitação de procedimentos invasivos por parte dos pacientes. Sendo assim, este trabalho teve como objetivo apresentar a resolução de uma reabilitação por meio de tratamento não invasivo e multidisciplinar. A paciente, gênero feminino, compareceu a clínica da faculdade apresentando próteses fixas mandibulares mal adaptadas bilateralmente, lesões endodônticas, recessão gengival nos dentes pilares e sensibilidade dentinária. Para a adequada resolução deste caso foi proposto à associação de implantes osseointegrados, prótese parcial fixa, exodontia e procedimentos periodontais estéticos, com a utilização de enxerto de tecido conjuntivo subepitelial. Após dois anos de pós-operatório, a paciente mostrou satisfação estética e mastigatória. Com base no caso apresentado, este trabalho discutiu os diversos fatores que podem afetar a escolha de uma determinada modalidade de tratamento, para a reabilitação de espaços edêntulos unitários.

Periodontitis is a chronic inflammatory disease that results in the destruction of teeth and their supporting tissues with subsequent tooth loss. The replacement of missing teeth for implant-supported restorations has proven to be a highly predictable treatment method with good long-term prognosis. However, some consequences of tooth loss prevents dental implant placement in an ideal position, where regenerative procedures are necessary for this type of rehabilitation. Less invasive procedures such as conventional prosthesis emerge as a therapeutic option in cases where there is enough bone structure for implants and patient´s non-acceptance for invasive procedures. Thus, this paper aims to present the resolution of rehabilitation through a noninvasive and multidisciplinary treatment. One female patient referred to the clinic presented maladaptive bilateral mandibular fixed prostheses, endodontic lesions, gingival recession, and root sensitivity. For proper resolution of this case, an association among osseointegrated implants, fixed partial prosthesis, tooth extraction, and aesthetic periodontal procedures with the use of subepithelial connective tissue graft was proposed. After two years, the patient shows excellent aesthetics and chewing. Within the limits of this scenario, this paper discusses the various factors that may affect the choice of a particular treatment modality for the rehabilitation of edentulous single spaces.

Prótesis parcial fija: análisis biomecánico sobre distribución de esfuerzos entre tresalternativas de retención / Fixed partial prosthesis: biomechanical analysis of stress distribution among three

Introducción: el propósito de este estudio fue analizar la distribución de los esfuerzos entre tres alternativas deretención de una prótesis dental parcial fija de tres unidades, utilizando el método de elementos finitos (MEF). Métodos: se realizaron tres modelos tridimensionales en elementos finitos del tramo dental anterior superior, restaurando uno con postes colados, otro con postes prefabricados y el tercero con implantes. Los modelos del tramo restaurado fueron modelados con hueso esponjoso, hueso cortical, ligamento periodontal, encía, raíz, gutapercha, cemento resinoso, poste, muñón de resina (modelos postes prefabricados), cofia metálica y corona cerámica. El material de los postes considerado para el análisis fue una aleación de metal noble (postes colados) y fibra de vidrio (postes prefabricados). Los postes fueron cementados con cemento resinoso. Se hizo un análisis lineal y se consideró las no linealidades asociadas a la geometría del modelo. Las variables incluidas en el modelado fueron el módulo de elasticidad y la razón de Poisson. Se aplicó una carga monótamente creciente de 1N en la superficie lingual de la corona con una inclinación de 45º. Los esfuerzos de von Mises fueron determinados. Resultados: el análisis de elementos finitos indicó que la distribución de los esfuerzos generados en el diente modelado con los postes disminuyó significativamente,de acuerdo con una relación inversamente proporcional al módulo de elasticidad del material. En el modelo con implante, los esfuerzos se concentraron en la zona cervical y en el implante mismo. Conclusiones: con las limitantes de este estudio, se encontróque existen variaciones marcadas con respecto a la distribución de los esfuerzos en las tres alternativas de retención, donde un sistema con varios componentes de diferente rigidez es cargado, el elemento más rígido resiste los mayores esfuerzos sin distorsión.

Introduction: the purpose of this study was to analyze the stress distribution among three retention alternativesused in a three unit fixed partial prosthesis, using the Finite Element Analysis (FEA). Methods: three tridimensional FEA modelsof the upper anterior area, restored with a cast post, another with a prefabricated post and the third one with an implant, were prepared. The models of the restored area consisted of trabecular bone, cortical bone, periodontal ligament, gingival, root, gutta-percha, resin luting cement, post, composite resin core (for prefabricated posts), metallic core and metal ceramic crown.The post materials considered for analysis were a noble casting alloy and fiber glass. The posts were cemented with resin luting cement. A lineal analysis was carried out and the nonlinearities associated with the geometry of the model, were considered. The variables included in the model were the modulus of elasticity and Poisson´s ratio. An increasing load of 1N was applied on the lingual surface of the crown with an inclination of 45°. Von Mises stress were then calculated. Results: the Finite Element Analysisshowed that the distribution of stresses generated on the tooth modeled with posts, decreased significantly, in accordance with an inverse proportional relation with the modulus of elasticity of the material. In the implant model, the stresses concentrated on the cervical area and on the implant itself. Conclusions: within the limitations of this study, it was found that that there were marked differences in relation with the stress distribution among the three retention alternatives, where the system with different rigidity components is loaded, the most rigid element is capable of resisting the highest stress without distortion.

Infraestructura de oro para prótesis metal-cerámicas obtenidas mediante técnica de electrodeposición / Infrastructure gold for metal-on-ceramic obtained by electrodeposition technique

La electrodeposición es un proceso químico por el cual se realiza una deposición galvánica de oro del 99% de pureza con el fin de obtener infraestructuras en prótesis metal-cerámicas. Las infraestructuras presentan, en promedio, un espesor de 0,2 mm y un desajuste marginal inferior la 20 µm, posibilitando la utilización de un mayor espesor de cerámica si la comparamos a técnicas convencionales. Esta técnica posibilita la disminución de la citotoxicidad, de las reacciones alérgicas y de la corrosión, determinando una mayor duración de las restauraciones. La coloración dorada del material permite al ceramista conseguir una estética más depurada, favoreciendo las tonalidades en la cerámica aplicada. Sin embargo, la necesidad de mano de obra calificada y de equipos modernos y de alto costo son factores que todavía hacen inviable la utilización de la electrodeposición de oro puro como práctica clínica habitual. El objetivo de este estudio es contribuir, a través de una revisión de la literatura, a la comparación en los siguientes factores: calidad del asentamiento marginal, durabilidad, biocompatibilidad, estética de las restauraciones cuyas estructuras hayan sido obtenidos por la técnica de electrodepoisición frente a restauraciones realizadas con técnicas metal-cerámicas convencionales y sistemas cerámicos

Electrodeposition is the galvanic deposition of 99% pure gold to obtain the framework for metal-ceramic prostheses. The framework is 0.2 mm thick, on average, with marginal maladjustment of less than 20 µm, enabling the use of greater ceramic thickness than that of conventional techniques. This new technique reduces cytotoxicity, allergic reactions and corrosion, resulting in longer restoration longevity. The golden coloration of the material allows the ceramist to develop a more evolved esthetic, favoring the tonality of the ceramic applied. However, the need for qualified labor and modern high-cost equipment are factors that hinder the use of electrodeposited pure gold in everyday clinical practice. The aim of this study is to perform a literature review to compare the quality of the marginal fit, longevity, biocompatibility, and esthetic of restorations whose copings were obtained by the electrodeposition technique using conventional metal-ceramics and ceramic systems