Sharps Accidents: Occurrence and Knowledge Level among Brazilian Dental Students

ABSTRACT Objective: To evaluate the prevalence of sharps accidents among dental students in southwest Goiás state, Brazil, and further survey their knowledge of biosafety and post-injury management. Material and Methods: A cross-sectional analytical observational study was carried out in 2018 following the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. The study population included dental students in the 4th and 10th course semester. A pre-formulated self-administered questionnaire containing 14 objective questions was used for data collection. Mean and standard deviation values were calculated. Results: A total of 308 responses were obtained. Overall, 15.9% of the respondents reported having previously experienced accidents with sharps. Most dental students who claimed to know the biological risks to which they are exposed were in the 5th and 8th course semesters, and 67.2% of them reported knowing how to proceed in the event of a sharp accident. Conclusion: A low prevalence of sharps accidents has been reported, and dental students are considered to have a good knowledge of biosafety.

Mechanical comparison of milled fiber-reinforced resin composite and Co-Cr frameworks with different connector cross-sectional geometries: An in vitro study.

This study compared the effect of using milled fiber-reinforced resin composite and Co-Cr (milled wax and lost-wax technique) frameworks for 4-unit implant-supported partial fixed dental prostheses; and also, evaluated the influence of the connector's cross-sectional geometries on the mechanical behavior. Three groups of milled fiber-reinforced resin composite (TRINIA) for 4-unit implant-supported frameworks (n = 10) with three connectors geometries (round, square, or trapezoid), and three groups of Co-Cr alloy frameworks manufactured by milled wax/lost wax and casting technique, were analyzed. The marginal adaptation was measured before cementation using an optical microscope. Then, the samples were cemented, thermomechanical cycled (load of 100 N/2 Hz, 106 cycles; 5, 37, and 55 ᵒC, a total of 926 cycles at each one), and cementation and flexure strength (maximum force) analyzed. Analysis of stress distribution in framework veneered considering resin and ceramic properties for fiber-reinforced and Co-Cr frameworks, respectively, implant, and bone was by finite element analysis under three contact points (100 N) on the central region. ANOVA and Multiple paired test-t with Bonferroni adjustment (α = 0.05) were used for data analysis. Fiber-reinforced frameworks showed better vertical adaptation (mean ranged from 26.24 to 81.48 µm) compared to the Co-Cr frameworks (mean ranged from 64.11 to 98.12 µm), contrary to horizontal adaptation (respectively, means ranged from 281.94 to 305.38 µm; and from 150.70 to 174.82 µm). There were no failures during the thermomechanical test. Cementation strength showed three times higher for Co-Cr compared to fiber-reinforced framework, as well as flexural strength (P < .001). Regarding stress distribution, fiber-reinforced had a pattern of concentration in the implant-abutment complex. There were no significant differences in stress values or changes observed among the different connector geometries or framework materials. Trapezoid connector geometry had a worse performance for marginal adaptation, cementation (fiber-reinforced 132.41 N; Co-Cr 255.68 N) and flexural strength (fiber-reinforced 222.57 N; Co-Cr 614.27 N). Although the fiber-reinforced framework showed lower cementation and flexural strength, considering the stress distribution values and absence of failures in the thermomechanical cycling test, it can be considered for use as a framework for 4-unit implant-supported partial fixed dental prostheses in the posterior mandible. Besides, results suggest that trapezoid connectors mechanical behavior did not perform well compared to round or square geometries.

The importance of properly distributing the occlusal load for the correct biomechanics of implant-supported fixed partial dentures: stress analysis in implants, prosthetic components and infrastructures / A importância da distribuição da carga oclusal de forma adequada para a correta biomecânica de prótese parcial fixa implantosuportada: análise das tensões em implantes, componentes protéticos e infraestruturas

ABSTRACT Objective: The present study analyzed the biomechanical behavior of the generated stress on the external surface of the rehabilitation elements (implants, components and infrastructures) according to different occlusion patterns on a fixed partial denture on osseointegrated implants. Method: The experimental groups varied according to the location of the occlusal load applied to the Fixed partial denture, with a total occlusal load of 750N in all groups, opting for greater loads on the occlusal table of the molar in relation to the premolar. This evaluation was performed by the finite element method with simulations by the AnsysWorkbench 16.0 Software program. Results: The results analyzed for implants and their components showed that the more posterior the occlusal loading, the greater the stress developed (group 4), always in the connection area between the prosthetic component and the implant, as this location can induce greater screw loosening. The results analyzed for the infrastructures showed that the most distributed occlusal loading possible (group 1) is the best situation for generating less stress. However, even in group 3 which obtained the highest stresses in the critical area of the prosthetic connection, the zirconia flexural strength values generated were not worrisome. Conclusion: It can be concluded that the occlusal adjustment of Fixed partial dentures are preponderant and decisive factors for correct biomechanics and preservation of the system in the long term in order to avoid possible damage and/or failures, and exert significant and notorious differences in the behavior of all structures studied herein.

RESUMO Objetivo: O presente estudo analisou o comportamento biomecânico do estresse gerado na superfície externa dos elementos reabilitadores (implantes, componentes e infraestruturas) de acordo com diferentes padrões de oclusão em uma prótese parcial fixa sobre implantes osseointegrados. Métodos: Os grupos experimentais variaram de acordo com a localização da carga oclusal aplicada na Prótese Parcial Fixa, com carga oclusal total de 750N em todos os grupos, optando por cargas maiores na mesa oclusal do molar em relação ao pré-molar. Esta avaliação foi realizada pelo método dos elementos finitos com simulações pelo programa AnsysWorkbench 16.0 Software. Resultados: Os resultados analisados para os implantes e seus componentes mostraram que quanto mais posterior a carga oclusal, maior a tensão desenvolvida (grupo 4), sempre na área de conexão entre o componente protético e o implante, pois este local pode induzir maior soltura do parafuso. Os resultados analisados para as infraestruturas mostraram que a carga oclusal mais distribuída possível (grupo 1) é a melhor situação para gerar menos estresse. No entanto, mesmo no grupo 3 que obteve as maiores tensões na área crítica da conexão protética, os valores de resistência à flexão da zircônia gerados não foram preocupantes. Conclusões: Pode-se concluir que o ajuste oclusal das Próteses Parciais Fixas são fatores preponderantes e decisivos para correta biomecânica e preservação do sistema a longo prazo a fim de evitar possíveis danos e/ou falhas, e exercem diferenças significativas e notórias no comportamento de todas as estruturas aqui estudadas.

Comparison of Conventional and Pontic Fixed Partial Dentures Over Implants Using the Finite Element Method: Three-Dimensional Analysis of Cortical and Medullary Bone Stress.

Rehabilitation with implant prostheses in posterior areas requires the maximum number of possible implants due to the greater masticatory load of the region. However, the necessary minimum requirements are not always present in full. This project analyzed the minimum principal stresses (TMiP, representative of the compressive stress) to the friable structures, specifically the vestibular face of the cortical bone and the vestibular and internal/lingual face of the medullary bone. The experimental groups were as follows: the regular splinted group (GR), with a conventional infrastructure on 3 regular-length Morse taper implants (4 × 11 mm); and the regular pontic group (GP), with a pontic infrastructure on 2 regular-length Morse taper implants (4 × 11 mm). The results showed that the TMiP of the cortical and medullary bones were greater for the GP in regions surrounding the implants (especially in the cervical and apical areas of the same region) but they did not reach bone damage levels, at least under the loads applied in this study. It was concluded that greater stress observed in the GP demonstrates greater fragility with this modality of rehabilitation; this should draw the professional's attention to possible biomechanical implications. Whenever possible, professionals should give preference to use of a greater number of implants in the rehabilitation system, with a focus on preserving the supporting tissue with the generation of less intense stresses.

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.

Photoelastic analysis of mandibular full-arch implant-supported fixed dentures made with different bar materials and manufacturing techniques.

PURPOSE: To compare the stress distribution of mandibular full dentures supported with implants according to the bar materials and manufacturing techniques using a qualitative photoelastic analysis. MATERIAL AND METHODS: An acrylic master model simulating the mandibular arch was fabricated with four Morse taper implant analogs of 4.5×6mm. Four different bars were manufactured according to different material and techniques: fiber-reinforced resin (G1, Trinia, CAD/CAM), commercially pure titanium (G2, cpTi, CAD/CAM), cobalt­chromium (G3, Co-Cr, CAD/CAM) and cobalt­chromium (G4, Co-Cr, conventional cast). Standard clinical and laboratory procedures were used by an experienced dental technician to fabricate 4 mandibular implant-supported dentures. The photoelastic model was created based on the acrylic master model. A load simulation (150N) was performed in total occlusion against the antagonist. RESULTS: Dentures with fiber-reinforced resin bar (G1) exhibited better stress distribution. Dentures with machined Co-Cr bar (G3) exhibited the worst standard of stress distribution, with an overload on the distal part of the posteriors implants, followed by dentures with cast Co-Cr bar (G4) and machined cpTi bar (G2). CONCLUSION: The fiber-reinforced resin bar exhibited an adequate stress distribution and can serve as a viable alternative for oral rehabilitation with mandibular full dentures supported with implants. Moreover, the use of the G1 group offered advantages including reduced weight and less possible overload to the implants components, leading to the preservation of the support structure.

Finite Element Analysis of Bone Stress in the Posterior Mandible Using Regular and Short Implants, in the Same Context, with Splinted and Nonsplinted Prostheses.

PURPOSE: The aim of this study was to compare the bone stress generated by rehabilitation using regular and short-length Morse taper implants (11 and 5 mm, respectively) in the same context and allied with splinted (SP) and nonsplinted (NSP) prostheses in the posterior area of the mandible using finite element analysis. MATERIALS AND METHODS: Three-dimensional geometric models using regular implants (Ø4 × 11 mm) and short implants (Ø4 × 5 mm) were simulated with a left posterior mandible that had the first premolar tooth and all teeth posterior to that premolar removed. The four experimental groups were as follows: Group 1 NSP (two regular implants and one short implant rehabilitated with nonsplinted prostheses), Group 1 SP (two regular implants and one short implant rehabilitated with splinted prostheses), Group 2 NSP (one regular implant and two short implants rehabilitated with nonsplinted prostheses), and Group 2 SP (one regular implant and two short implants rehabilitated with splinted prostheses). Oblique forces were simulated in molars (365 N) and premolars (200 N). Qualitative and quantitative analyses of the minimum principal stress in bone were performed using the ANSYS Workbench software, version 10.0. RESULTS: The splinted prostheses decreased the stress to the surrounding bone of short implants. Moreover, they also decreased the stress on the surrounding bone adjacent to the tooth. However, the splinted prostheses generated higher stress in the coverage of the surrounding bone for regular intermediate implants and prominently in the bone at the implant cervical region, at the edge crest, compared with the individualized groups. CONCLUSION: The benefits in the use of splinted prostheses are notable for the preservation of the bone surrounding the short implants and tooth; however, it is necessary to evaluate each clinical situation because, in this context, the regular implants are at higher stress than the individualized implants.

A Three-Dimensional Finite Element Analysis of the Stress Distribution Generated by Splinted and Nonsplinted Prostheses in the Rehabilitation of Various Bony Ridges with Regular or Short Morse Taper Implants.

PURPOSE: The aim of this study was to compare the biomechanical performance of splinted or nonsplinted prostheses over short- or regular-length Morse taper implants (5 mm and 11 mm, respectively) in the posterior area of the mandible using finite element analysis. MATERIALS AND METHODS: Three-dimensional geometric models of regular implants (Ø 4 × 11 mm) and short implants (Ø 4 × 5 mm) were placed into a simulated model of the left posterior mandible that included the first premolar tooth; all teeth posterior to this tooth had been removed. The four experimental groups were as follows: regular group SP (three regular implants were rehabilitated with splinted prostheses), regular group NSP (three regular implants were rehabilitated with nonsplinted prostheses), short group SP (three short implants were rehabilitated with splinted prostheses), and short group NSP (three short implants were rehabilitated with nonsplinted prostheses). Oblique forces were simulated in molars (365 N) and premolars (200 N). Qualitative and quantitative analyses of the minimum principal stress in bone were performed using ANSYS Workbench software, version 10.0. RESULTS: The use of splinting in the short group reduced the stress to the bone surrounding the implants and tooth. The use of NSP or SP in the regular group resulted in similar stresses. CONCLUSIONS: The best indication when there are short implants is to use SP. Use of NSP is feasible only when regular implants are present.

Celulite facial em lábio inferior oriunda de acne inflamada: relato de caso

A celulite facial é a difusão de processo inflamatório por planos subcutâneos em tecidos moles, podendo ter sua etiologia oriunda de variados fatores, sendo, dentre eles, a origem odontogênica a mais comumente encontrada. Entretanto, a celulite facial pode também estar relacionada a causas menos comuns, como processos infecciosos de origem não odontogê- nica. Objetivo: o presente relato de caso vem a elucidar o início de um processo infeccioso gerado por acne inflamada na borda inferior do lábio, a qual foi a porta de entrada para bactérias, o que gerou a difusão do processo inflamatório para planos subcutâneos e originou uma celulite facial. Relato de caso: pelo fato de não haver agente causal específico, como as originadas por causa odontogênica, foi estabelecido tratamento com antibióticoterapia de amplo espectro, associado à meticulosa higienização e terapia com calor, a fim de induzir abscedação espontânea. Exames específicos laboratoriais também foram solicitados para maior segurança e diagnóstico preciso do profissional. A evolução do caso transcorreu em oito dias, de forma rápida e aguda, principalmente nos primeiros cinco dias. Considerações finais: conforme relatado no caso, a interação entre o cirurgião-dentista e o médico bem como a presença da interdisciplinaridade foram fatores fundamentais no tratamento como um todo e para a resolução do caso de forma satisfatória, uma vez que a ocorrência de celulite facial nessa área não é geralmente presenciada.

Three-Dimensional Finite Element Analysis Surface Stress Distribution on Regular and Short Morse Taper Implants Generated by Splinted and Nonsplinted Prostheses in the Rehabilitation of Various Bony Ridges.

AIMS: This study used finite element analysis to compare the biomechanical performance of splinted (SP) and nonsplinted (NSP) prostheses to regular and short length Morse taper implants in the posterior side of the mandible. METHODS: The authors used 3-dimensional geometric models of regular implants (∅4 × 11 mm) and short implants (∅4 × 5 mm) housed in the corresponding bone edges of the posterior left mandibular hemiarch involving tooth 34. The 8 experimental groups were: the control group SP (3 regular implants rehabilitated with SP), group 1SP (2 regular and 1 short implants rehabilitated with SP), group 2SP (1 regular and 2 short implants rehabilitated with SP), group 3SP (3 short implants rehabilitated with SP), the control group NSP (3 regular implants rehabilitated with NSP), group 1NSP (2 and 1 short implants rehabilitated with NSP), group 2NSP (1 regular and 2 short implants rehabilitated with NSP), and group 3NSP (3 short implants rehabilitated with NSP). Oblique forces were simulated in the molars (365 N) and premolars (200 N). Qualitative and quantitative analysis of the distribution of Von Mises equivalent stress (implants, components, and infrastructure) was performed using the AnsysWorkbench10.0 software. RESULTS AND CONCLUSIONS: The results showed that the use of SP provides several advantages and benefits, reducing the stresses placed on the implant surface, on the transmucosal abutment areas and on the interior region of the infrastructure. The use of NSP was advantageous in reducing the stresses on the abutments and in the distal interproximal area of connection between the crowns.

Subcutaneous emphysema after treatment through airabrasivedevice: case report / Enfisema subcutâneo gerado após tratamento com equipamento de ar comprimido: relato de caso

Subcutaneous emphysema is an event often generated by iatrogenic reason, caused by improper dissection of air into soft tissues and/ or anatomical structures, causing edema and visually noticeable volumetric change in the area of the incident. The main etiological factor for this is the use of equipment such as air syringe or high-speed handpieces in surgical procedures of greater magnitude; however, subcutaneous emphysema may also occur in simple procedures, such that presented in this case report, through using air-abrasive device usually proper for dental prophylaxis. This case report aimed to describe the care measurements to avoid such event, describing proper procedures for the correct solution of the case, as well as to alert the professionals about the risks and necessary precautions.

O enfisema subcutâneo é um evento muitas vezes de origem iatrogênica, causado pela infusão indevida de ar nos tecidos e/ou estruturas anatômicas, causando edemaciamento e alteração volumétrica visualmente perceptível na área do ocorrido. O principal fator etiológico para tal é o uso de equipamentos como seringa tríplice ou caneta de alta rotação durante procedimentos cirúrgicos de maior magnitude; no entanto, o enfisema subcutâneo também pode ocorrer diante de procedimentos mais simples, tal como o ocorrido no presente relato de caso, em que houve sua ocorrência pelo uso de equipamento de ar comprimido usualmente utilizado para execução de profilaxia. O objetivo do presente artigo foi relatar o caso, assim como descrever os cuidados para se evitar tal evento, e descrever procedimentos adequados para o correto prosseguimento e resolução adequada do caso.

Desenvolvimento de técnica para fidelização e otimização do tempo na captura de provisório imediato sobre implante em posicionamento ideal / Development of technique to fidelize and optimize treatment time in capturing of immediate provisional on optimal positioning

A Implantodontia caracterizou-se como um dos grandes avan‡os dentro da Odontologia moderna. Nas £ltimas d‚cadas, as inova‡ães e desenvolvimento dos implantes dent rios tˆm sido crescentes, e na necessidade de acompanhar tais evolu‡ães, as t‚cnicas no campo das pr¢teses e reabilita‡ães tamb‚m tiveram de se reinventar. Atualmente, um dos grandes trunfos do uso dos implantes dent rios ‚ associ -los a uma restaura‡Æo imediatamente ap¢s sua implanta‡Æo, com ganhos funcionais e, especialmente, est‚ticos. A previsibilidade do tratamento ‚ indispens vel no sucesso do mesmo. Assim, ‚ poss¡vel prever o posicionamento mais ideal para a restaura‡Æo imediata. Al‚m disso, configura-se como indispens vel a rapidez do procedimento, uma vez que quanto menos exposto ficar o campo cir£rgico, melhor ser  o comportamento p¢s-operat¢rio da regiÆo reabilitada. Portanto, no intuito de se conciliar fidelidade de posicionamento da restaura‡Æo imediata com rapidez e otimiza‡Æo do tempo transoperat¢rio, este artigo e seus autores se propãem a compartilhar uma t‚cnica desenvolvida para viabiliza‡Æo de tal procedimento de forma r pida e previs¡vel (T‚cnica da muralha e faceta adaptada - Palhares e Toniollo).

Implantology is one of the great advances in modern Dentistry. In recent decades innovations and development of dental implants are occurring continuously thereby techniques and rehabilitation also had to be reinvented. Currently, one of the great advantages of the use of dental implants is the possibility of associating them to a restoration immediately after their deployment, with functional and especially aesthetic gains. Predictability is essential to the success of the treatment. Thus, it is possible to predict the most optimal placement for the immediate restoration. Accelerating the procedure also seems to be fundamental since the less exposed the surgical field, the better the postoperative behavior of the rehabilitated area. Therefore, in order to reconcile fidelity and fast positioning of the immediate restoration to optimize time, this article and its authors intended to share a technique developed for the feasibility of this procedure in a quick and way (Technique of the wall and adapted veneer - Palhares and Toniollo).

Moldagem personalizada do perfil de emergência para otimização estética e respeito aos tecidos peri-implantares / Customized molding of the emergency profile for aesthetics optimization and respect to peri-implants tissue

pós o advento e sucesso comprovado da ósseointegração, a Implantodontia teve sua ascensão de forma rápida, previsível, consolidada e resolutiva. Para o efetivo e correto funcionamento do tratamento reabilitador utilizando os implantes dentários é necessário que se respeite os diversos fatores que permeiam seu comportamento biomecânico, mas também que se preze pelos fatores diretamente atrelados ao sucesso esperado pelo paciente que, muitas vezes, é relacionado à chamada “estética vermelha”, a qual tem extrema responsabilidade no resultado final do tratamento. Para isso, não só a fim de obter contorno, suporte e harmonia do tecido mole marginal à prótese sobre implante, mas também visando a manutenção e respeito a essa estrutura tão nobre, faz-se conveniente a moldagem personalizada do perfil de emergência da referida região, principalmente em casos unitários, a fim de preservar toda a estrutura conseguida por meio do uso dos provisórios. Este artigo traz um relato de caso clínico em que tal procedimento de extrema valia é descrito detalhadamente no intuito de ser reproduzível por outros profissionais da área na intenção de se obter máximo resultado estético, respeitando-se as estruturas nobres circunjacentes ao implante e respectiva reabilitação.

After the advent and proven success of osseointegration, Implantology raised quickly, predictably, in a consolidated and resolute way. For effective and proper effect of rehabilitation treatment with dental implants it is necessary to respect the various factors involved in its biomechanical behavior, but also by respect the expectation of the patient regarding the success of the treatment. This is often related to the call “red aesthetic” that has an important role on the treatment outcome. Therefore besides obtaining contour, support, and harmony of the peri-implant soft tissue, in order to maintain and respect this noble structure, it is recommended to make a customized molding of the emergency profile of that region, especially in single cases, preserving the whole structure obtained through the use of provisional prosthesis. This article presents a case report in which this procedure is described in details so that other professionals may reproduce it in an attempt to obtain maximum aesthetic result respecting the noble structures surrounding the implant and their rehabilitation

Protocolo inferior com carga imediata: implicações laboratoriais / Inferior protocol with immediate loading: laboratory

O protocolo proposto por Branemark em 19854 era composto por duas fases cirúrgicas, com tempos de espera para mandíbula de 3 a 4 meses, e para maxila de 4 a 6 meses, e após esse período era iniciada a instalação das próteses. Ao longo dos anos houve o aumento da utilização de carga imediata em implantes osseointegráveis na região anterior da mandíbula sendo efetuada com sucesso, analisando-se cuidadosamente e individualmente cada caso, respeitando suas particularidades anatômicas, histológicas e fisiológicas. A realização do protocolo com carga imediata funcional demonstrou-se com bom resultado clinico e alto grau de satisfação do paciente, destacando-se ainda a redução de custos e a diminuição do tempo do tratamento como benefícios comprovados, contribuindo ainda mais com a função e estética restabelecida de modo satisfatório. No entanto, para tal, a sincronia entre cirurgião-dentista e protético deve estar aguçada a fim de que se possam realizar todos os procedimentos necessários em até 48 horas de serviço. O presente artigo tem o intuito de esclarecer todos os procedimentos técnicos clínicos e, principalmente, laboratoriais, para que os profissionais da área entendam quais os procedimentos envolvidos no processo e quão sensíveis eles são

Three-dimensional finite element analysis of the stress distribution on morse taper implants surface.

PURPOSE: This finite element analysis (FEA) compared stress distribution on external surface of different morse taper implants, varying implant bodies length and dimensions of metal-ceramic crowns in order to maintain the occlusal alignment. METHODS: Three-dimensional finite element (FE) models were designed representing a posterior left side segment of the mandible: group 0, 3 implants of 11 mm length; group 1, implants of 13 mm, 11 mm and 5mm length; group 2, 1 implant of 11 mm and 2 implants of 5mm length; group 3, 3 implants of 5mm length. The abutments heights were 3.5mm for 13 mm and 11 mm implants (regular) and 0.8mm for 5mm implants (short). Evaluation was performed on a computer program (Ansys software), with oblique loads of 365N for molars and 200 N for premolars, applied on ridges of cusps and grooves. RESULTS: Abutments with 0.8mm height generated less von Mises stresses compared with 3.5mm height. The use of short implants associated with bigger crowns concentrated higher stress distribution and stress values on the surface implants, principally on the vestibular side (oblique direction of the loads). The more distal implant concentrated higher stress. CONCLUSIONS: Moreover, these 5mm implants were positioned at the cortical bone level, which has higher elastic modulus and may have influenced at the stress distribution. However, despite the higher stresses, these implants were well able to withstand the applied forces.

Morse taper implants at different bone levels: a finite element analysis of stress distribution

Aim: To explore the biomechanical effects of the different implantation bone levels of Morse taper implants, employing a finite element analysis (FEA). Methods: Dental implants (TitamaxCM) with 4x13 mm and 4x11 mm, and their respective abutments with 3.5 mm height, simulating a screwed premolar metal-ceramic crown, had their design performed using the software AnsysWorkbench10.0. They were positioned in bone blocks, covered by 2.5 mm thickness of mucosa. The cortical bone was designed with 1.5 mm thickness and the trabecular bone completed the bone block. Four groups were formed: group 11CBL (11 mm implant length on cortical bonelevel), group 11TBL (11 mm implant length on trabecular bone level), group 13CBL (13mm implant length on cortical bone level) and group 13TBL (13 mm implant length on trabecular bonelevel). Oblique 200 N loads were applied. Von Mises equivalent stresses in cortical and trabecular bones were evaluated with the same design program. Results: The results were shown qualitatively and quantitatively by standard scales for each type of bone. By the results obtained, it can be suggested that positioning the implant completely in trabecular bone brings harm with respect to the generated stresses. Its implantation in the cortical bone has advantages with respect to better anchoring and locking, reflecting a better dissipation of the stresses along the implant/bone interfaces. In addition, the search for anchoring the implant in its apical region in cortical bone is of great value to improve stabilization and consequently better stress distribution.Conclusions: The implant position slightly below the bone in relation to the bone crest brings advantages as the best long-term predictability with respect to the expected neck bone loss.

Three-dimensional finite element analysis of stress distribution on different bony ridges with different lengths of morse taper implants and prosthesis dimensions.

This finite element analysis (FEA) compared stress distribution on different bony ridges rehabilitated with different lengths of morse taper implants, varying dimensions of metal-ceramic crowns to maintain the occlusal alignment. Three-dimensional FE models were designed representing a posterior left side segment of the mandible: group control, 3 implants of 11 mm length; group 1, implants of 13 mm, 11 mm and 5 mm length; group 2, 1 implant of 11 mm and 2 implants of 5 mm length; and group 3, 3 implants of 5 mm length. The abutments heights were 3.5 mm for 13- and 11-mm implants (regular), and 0.8 mm for 5-mm implants (short). Evaluation was performed on Ansys software, oblique loads of 365N for molars and 200N for premolars. There was 50% higher stress on cortical bone for the short implants than regular implants. There was 80% higher stress on trabecular bone for the short implants than regular implants. There was higher stress concentration on the bone region of the short implants neck. However, these implants were capable of dissipating the stress to the bones, given the applied loads, but achieving near the threshold between elastic and plastic deformation to the trabecular bone. Distal implants and/or with biggest occlusal table generated greatest stress regions on the surrounding bone. It was concluded that patients requiring short implants associated with increased proportions implant prostheses need careful evaluation and occlusal adjustment, as a possible overload in these short implants, and even in regular ones, can generate stress beyond the physiological threshold of the surrounding bone, compromising the whole system.

Effect of fluoride sodium mouthwash solutions on cpTI: evaluation of physicochemical properties

The effects of fluoride, which is present in different oral hygiene products, deserve more investigation because little is known about their impact on the surface of titanium, which is largely used in Implantology. This study evaluated the surface of commercially pure titanium (cpTi) after exposure to different concentrations of sodium fluoride (NaF). The hypothesis tested in this study was that different concentrations of NaF applied at different time intervals can affect the titanium surface in different ways. The treatments resulted in the following groups: GA (control): immersion in distilled water; GB: immersion in 0.05% NaF for 3 min daily; GC: immersion in 0.2% NaF for 3 min daily; GD: immersion in 0.05% NaF for 3 min every 2 weeks; and GE: immersion in 0.2% NaF for 3 min every 2 weeks. The experiment lasted 60 days. Roughness was measured initially and every 15 days subsequently up to 60 days. After 60 days, corrosion analysis and anodic polarization were done. The samples were examined by scanning electron microscopy (SEM). The roughness data were analyzed by ANOVA and there was no significant difference among groups and among time intervals. The corrosion data (i corr) were analyzed by the Mann-Whitney test, and significant differences were found between GA and GC, GB and GC, GC and GD, GC and GE. SEM micrographs showed that the titanium surface exposed to NaF presented corrosion that varied with the different concentrations. This study suggests that the use of 0.05% NaF solution on cpTi is safe, whereas the 0.2% NaF solution should be carefully evaluated with regard to its daily use.

Os efeitos do fluoreto, o qual está presente em diferentes produtos de higiene oral, necessita de maiores investigações, pois pouco se sabe sobre seus efeitos na superfície do titânio, o qual possui amplo uso na implantodontia. Este estudo objetivou avaliar a superfície do titânio comercialmente puro (cpTi) após exposição a diferentes concentrações de fluoreto de sódio (NaF). A hipótese testada neste estudo foi que diferentes concentrações de NaF aplicadas em diferentes intervalos de tempo seriam capazes de afetar diferentemente a superfície do titânio. Os tratamentos realizados foram: GA (controle): imersão em água destilada; GB: imersão diária por 3 min em NaF a 0,05%; GC: imersão diária por 3 min em NaF a 0,2%; GD: imersão quinzenal por 3 min em NaF a 0,05%; e GE: imersão quinzenal por 3 min em NaF a 0,2%. O tempo do experimento foi de 60 dias. A análise da rugosidade foi efetuada inicialmente e a cada 15 dias. Após 60 dias foi realizada análise de corrosão e polarização anódica. As amostras foram analisadas em MEV. Os dados de rugosidade foram analisados por ANOVA e não houve diferença estatisticamente significante entre grupos e entre tempos. Os dados de corrosão (i corr) foram analisados pelo teste de Mann-Whitney e foram encontradas diferenças significantes entre GA e GC, GC e GB, GC e GD, GC e GE. A MEV evidenciou que a superfície do titânio exposto ao NaF apresentou corrosão variando de acordo com a concentração. Com base nos dados encontrados conclui-se que o uso de solução NaF a 0,05% em cpTi é seguro, enquanto a solução NaF 0,2% para uso diário deve ser cuidadosamente avaliada.

Problemas na junção implante/prótese: uma alternativa para resolução do caso / Problems at the implant/prosthesis junction: an alternative for solving the case

A Implantodontia vem se destacando entre as diversas áreas da Odontologia moderna. As possibilidades de tratamento envolvendo os implantes dentários têm facilitado e ampliado a gama de opções ao cirurgião dentista. No entanto, a proposta de tratamento envolvendo reabilitação sobre implantes traz consigo problemas a serem solucionados, já que tal tratamento também é passível de intercorrências. A curva de aprendizagem com o emprego da Implantodontia deve ser respeitada, já que tanto na fase cirúrgica quanto na fase protética, existem critérios a serem respeitados para um bom prognóstico do tratamento. Além disso, quando surgem as intercorrências é imprescindível o preparo e conhecimento do profissional em questão. O presente caso clínico relata uma reabilitação unitária sobre implante, a qual necessitou ser realizada fora dos padrões normais da Implantodontia, já que foi constatada deformação na plataforma hexagonal do mesmo. É possível que tal ocorrência tenha sido causada na fase cirúrgica, durante a instalação do implante, devido a um provável torque excessivo, resultando na impossibilidade da adaptação dos componentes protéticos. A resolução do caso ocorreu com a instalação de um núcleo metálico fundido sobre o implante e confecção de prótese metalocerâmica cimentada. Com o presente relato, pode-se notar a importância do conhecimento de conceitos básicos por parte do cirurgião dentista, assim como sua flexibilidade frente às intercorrências do tratamento

The Implantology has become highlighted among the various areas of modern dentistry. The treatment possibilities involving dental implants have facilitated and expanded the range of options to the dentist. However, the treatment involving rehabilitation with implants can bring problems to be solved, as this treatment is also susceptible to complications. Learning curve with the use of implants should be respected, both in the surgical and prosthetic phases, because there are criteria to be met for a good treatment prognosis. Also, when complications occur, it is essential preparation and knowledge of the professional. This case report describes unit rehabilitation with implant, which needed to be performed outside of the normal standards of implant dentistry, as was observed deformation on the hexagonal platform. It is possible that it has been caused during implant installation surgery phase, due to an excessive torque, resulting in the inability to adapt the prosthetic components. The case resolution was with the installation of a cast metal core on the implant and making a metaloceramic cemented prosthesis. With this case report may be noted the importance of knowledge of basic concepts by the dentist, as well as its flexibility in the face of complications of treatment

Effect of fluoride sodium mouthwash solutions on cpTI: evaluation of physicochemical properties.

The effects of fluoride, which is present in different oral hygiene products, deserve more investigation because little is known about their impact on the surface of titanium, which is largely used in Implantology. This study evaluated the surface of commercially pure titanium (cpTi) after exposure to different concentrations of sodium fluoride (NaF). The hypothesis tested in this study was that different concentrations of NaF applied at different time intervals can affect the titanium surface in different ways. The treatments resulted in the following groups: GA (control): immersion in distilled water; GB: immersion in 0.05% NaF for 3 min daily; GC: immersion in 0.2% NaF for 3 min daily; GD: immersion in 0.05% NaF for 3 min every 2 weeks; and GE: immersion in 0.2% NaF for 3 min every 2 weeks. The experiment lasted 60 days. Roughness was measured initially and every 15 days subsequently up to 60 days. After 60 days, corrosion analysis and anodic polarization were done. The samples were examined by scanning electron microscopy (SEM). The roughness data were analyzed by ANOVA and there was no significant difference among groups and among time intervals. The corrosion data (i(corr)) were analyzed by the Mann-Whitney test, and significant differences were found between GA and GC, GB and GC, GC and GD, GC and GE. SEM micrographs showed that the titanium surface exposed to NaF presented corrosion that varied with the different concentrations. This study suggests that the use of 0.05% NaF solution on cpTi is safe, whereas the 0.2% NaF solution should be carefully evaluated with regard to its daily use.