Influence of diameter in the stress distribution of extra-short dental implants under axial and oblique load: a finite element analysis

Aim: This study evaluated the influence of a wide diameter on extra-short dental implant stress distribution as a retainer for single implant-supported crowns in the atrophic mandible posterior region under axial and oblique load. Methods: Four 3D digital casts of an atrophic mandible, with a single implant-retained crown with a 3:1 crown-to-implant ratio, were created for finite element analysis. The implant diameter used was either 4 mm (regular) or 6 mm (wide), both with 5 mm length. A 200 N axial or 30º oblique load was applied to the mandibular right first molar occlusal surface. The equivalent von Mises stress was recorded for the abutment and implant, minimum principal stress, and maximum shear stress for cortical and cancellous bone. Results: Oblique load increased the stress in all components when compared to axial load. Wide diameter implants showed a decrease of von Mises stress around 40% in both load directions at the implant, and an increase of at least 3.6% at the abutment. Wide diameter implants exhibited better results for cancellous bone in both angulations. However, in the cortical bone, the minimum principal stress was at least 66% greater for wide than regular diameter implants, and the maximum shear stress was more than 100% greater. Conclusion: Extra-short dental implants with wide diameter result in better biomechanical behavior for the implant, but the implications of a potential risk of overloading the cortical bone and bone loss over time, mainly under oblique load, should be investigated

Implant digital impression accuracy using extraoral scanners: a three-dimensional analysis

Aim: To analyze the accuracy of extraoral systems (Ceramill Map400+, AutoScan-DS200+, and E2) in full implantprosthetic rehabilitation three-dimensionally. Methods: A metallic edentulous maxilla with four implants was digitalized by a contact scanner (MDX-40 - Roland, control) and used as a control image to compare with other images generated by three laboratory scanners (10 samples per group). Letters identified all the four components: A and D angled 45º, and B and C parallel. The BioCAD software exported the images (.STL) to compare and verify deviations of the analogs on the X, Y, and Z axes. The nonparametric Kruskal-Wallis test and the two-way ANOVA on ranks with a post hoc Tukey test analyzed the data with 5% significance. Results: No statistical differences were observed in the accuracy between the extraoral scanners (p=0.0806). However, when analyzing only the components, component D was more accurate when scanned with Ceramill Map400+ compared with AutoScan DS200+ (p<0.001) and with E2 (p=0.002). Conclusions: All extraoral systems assessed showed digitalization accuracy but with more deviations in angled implants. The Ceramill Map400+ scanner showed the best results for the digital impression of a complete arch

Does the Use of Surface Electromyography Could Improve Quality of Life among Patients Rehabilitated by Mandibular Overdentures on Different Attachments?

Abstract Objective: To analyze and compare changes of quality of life parameter among dental patients rehabilitated by the implant-supported overdentures with different attachment systems. Material and Methods: Forty-eight patients were recruited as a study cohort. The implant placement procedure was based on the results obtained by CBCT scanning and individualized surgical templates manufactured for correct implant placement. Each individual received two k3Pro Implants (Sure Type with 4.0 or 4.5 mm in diameter) at the intraforaminal area due to standard protocol of implantation provided by the manufacturer under local anesthesia. All patients were distributed between two groups based on the fact of using either Locator- or ball-attachments. Rank correlation was measured using Spearman correlation coefficient, while linear correlation was evaluated by Pearson correlation coefficient. Results: No statistically meaningful differences were noted regarding patients' distribution among groups considering age (p>0.05) and gender (p>0.05). Provided patient-level analysis demonstrated that increase of conventional full denture service time was positively correlated with escalation of OHIP-EDENT scores. The most prominent inter-correspondences were noted specifically between longevity of denture service and elevation of scores within "Functional limitation" (r=0.61; p<0.05), "Physical pain" (r=0.51; p<0.05) and "Physical disability" (r=0.57; p<0.05) subdomains. No statistically argumented regressions were noted between increase tendency of OHIP-EDENT scores and gender (p>0.05) or age (p>0.05) parameters. Conclusion: Significant improvements of quality of life measured with OHIP-EDENT were noted for both types of attachments compared to the pre-treatment situation independently of additionally provided surface electromyography-based alignment.

Bone evaluation of single edentulous areas of maxilla: short communication / Avaliação óssea de regiões maxilares candidatas à reabilitação unitária implantossuportada: uma comunicação curta

Objective: Evaluate the height and bone thickness in healed sites of single implant areas. Materials and Methods:In this cross-sectional study, cone-beam computed tomography (CBCT) images of single edentulous areas of maxilla of patients who needed aesthetic single implant rehabilitations were evaluated for measure the height and thickness using an implant planning software. Data were statistically analyzed using the Mann-Whitney and Pearson correlation test, considering the time, reason and region of tooth loss. For all tests, a p-value <0.05 was considered significant. Results: 48 patients with single tooth loss were included. The statistical analysis demonstrated that reason for the loss was not related to height or bone thickness. Bone thickness was statis-tical significant higher in the posterior region. For the anterior region, the bone thickness was significantly higher when the tooth was lost within 5 years. Pearson correlation test showed a moderate negative signifi-cant correlation between time of tooth loss and bone thickness in anterior region. Conclusion: Reason for tooth loss had no influence on the bone measurements of the residual ridge. In contrast, bone thickness may vary according to the region of tooth loss. The time of tooth loss and bone thickness in the anterior region were inversely proportional. Registration number at https://ensaiosclinicos.gov.br/rg/RBR-5cnyjj.

Objetivo: Avaliar a altura e espessura óssea em sítios unitários cicatrizados. Materiais e Métodos: Neste estudo transversal, imagens de tomografia computa-dorizada de feixe cônico (TCFC) de regiões edêntulas unitárias maxilares de pacientes candidatos a reabilitação unitária implantossuportada foram mensuradas em relação à altura e espessura óssea usando um software de planejamento de implante. Os dados foram analisados estatisticamente por meio do teste Mann-Whitney e de correlação de Pearson, considerando o tempo, o motivo e região da perda dentária. Para todos os testes, um valor de p <0,05 foi considerado significativo. Resultados: Foram incluídos 48 pacientes com perda dentária unitária. A análise estatística demonstrou que o motivo da perda dentária não influenciou na altura ou na espessura óssea. A espessura óssea foi estatisticamente maior na região posterior. Para a região anterior, a espessura óssea foi significativamente maior quando o dente foi perdido em até 5 anos. O teste de correlação de Pearson demonstrou uma correlação significativa negativa moderada entre o tempo de perda do dente e a espessura óssea na região anterior. Conclusão: O motivo da perda dentária não influenciou nas medidas ósseas do rebordo residual. Em contraste, a espessura do osso pode variar de acordo com a região da perda dentária. O tempo de perda dentária e a espessura óssea da região anterior foram inversamente proporcionais. Número de registro em https://ensaiosclinicos.gov.br/rg/RBR-5cnyjj

Marginal misfit of heat-pressed milled wax-pattern and CAD/CAM crowns and its effect on stress distribution in implant-supported rehabilitations

Aim: To compare the marginal fit of lithium disilicate CAD/CAM crowns and heat-pressed crowns fabricated using milled wax patterns, and evaluate its effect on stress distribution in implantsupported rehabilitation. Methods: A CAD model of a mandibular first molar was designed, and 16 lithium disilicate crowns (8/group) were obtained. The crown-prosthetic abutment set was evaluated in a scanning electron microscopy. The mean misfit for each group was recorded and evaluated using Student's t-test. For in silico analysis, a virtual cement thickness was designed for the two misfit values found previously, and the CAD model was assembled on an implant-abutment set. A load of 100 N was applied at 30° on the central fossa, and the equivalent stress was calculated for the crown, titanium components, bone, and resin cement layer. Results: The CAD/CAM group presented a significantly (p=0.0068) higher misfit (64.99±18.73 µm) than the heat-pressed group (37.64±15.66 µm). In silico results showed that the heat-pressed group presented a decrease in stress concentration of 61% in the crown and 21% in the cement. In addition, a decrease of 14.5% and an increase of 7.8% in the stress for the prosthetic abutment and implant, respectively, was recorded. For the cortical and cancellous bone, a slight increase in stress occurred with an increase in the cement layer thickness of 5.9% and 5.7%, respectively. Conclusion: The milling of wax patterns for subsequent inclusion and obtaining heat-pressed crowns is an option to obtain restorations with an excellent marginal fit and better stress distribution throughout the implant-abutment set

Prosthetic dental management of a patient with anhidrotic ectodermal dysplasia: a case report / Manejo protésico dental de un paciente con displasia ectodérmica anhidrótica: reporte de caso

Introduction: Ectodermal dysplasia (ED) comprises a broad group of genetic disorders characterized by alterations of the structures derived from the ectoderm, including those of the stomatognathic system. Case Report: The present article aims to report the prosthetic management of a patient with anhidrotic ectodermal dysplasia. A male patient diagnosed with ED who attended the dental consultation displaying oligodontia; underdeveloped alveolar ridges were observed. Results: The established treatment consisted of the adaptation of implant-supported fixed full-arch prosthesis designed through CAD-CAM technology for the lower jaw and of a removable partial prosthesis with muco-dental support for the upper jaw. The dental approach of patients with ED is based on a correct analysis of the facial characteristics and stomatological conditions of each subject. Conclusion: A multidisciplinary approach is mandatory due to the biological and functional complexity in biomechanical terms of these individuals.

Introducción: La displasia ectodérmica (DE) comprende un amplio grupo de trastornos genéticos caracterizados por alteraciones de las estructuras derivadas del ectodermo, incluidas las del sistema estomatognático. Reporte de Caso: El presente artículo tiene como objetivo informar del manejo protésico de un paciente con displasia ectodérmica anhidrótica. Paciente varón diagnosticado de DE acudió a consulta odontológica por oligodoncia; Se observaron crestas alveolares subdesarrolladas. Resultados: El tratamiento establecido consistió en la adaptación de una prótesis de arcada completa fija implantosoportada diseñada mediante tecnología CAD-CAM para el maxilar inferior y de una prótesis parcial removible con soporte muco-dental para el maxilar superior. El abordaje odontológico de los pacientes con DE se basa en un correcto análisis de las características faciales y condiciones estomatológicas de cada sujeto. Conclusión: Un enfoque multidisciplinario es obligatorio debido a la complejidad biológica y funcional en términos biomecánicos de estos individuos.

Complicações precoces em próteses parciais fixas implantossuportadas de zircônia monolítica e bicamada: estudo prospectivo, randomizado, de boca dividida / Early complications in fixed partial prosthesis implants supported with monolithic and bilayer zirconia: a prospective, randomized, split-mouth study

As coroas de cerâmica pura estão ganhando força na odontologia uma vez que as exigências estéticas e mecânicas são cada vez mais evidentes, uma vez que as próteses metal free do tipo bicamada, não raramente, apresentam lascamento da cerâmica de cobertura como a principal falha a longo prazo, então iniciou-se o uso de próteses monolíticas. Paralelamente é crescente a busca e o uso de implantes osseointegráveis para suportar as reabilitações parciais, sendo a primeira opção para as reabilitações orais de áreas edêntulas. Logo, o objetivo deste estudo clínico prospectivo, randomizado de boca dividida é avaliar o desempenho clínico e a previsibilidade, caracterizando o número e o tipo de complicações e falhas precoces como desgaste do antagonista, perda óssea, inflamação gengival e falhas mecânicas que possam ocorrer em PPFs de três elementos implantossuportadas com retenção mista em região posterior de mandíbula em zircônia monolítica e infraestrutura de zircônia com cerâmica de cobertura, além de avaliar a percepção estética e satisfação do paciente com cada uma delas. Os pacientes selecionados (N=2) passarão por procedimentos cirúrgicos para instalação de dois implantes na região posterior de mandíbula, sendo dois de cada lado. Após três a quatro meses os cicatrizadores serão instalados e a moldagem será realizada para confecção das próteses seguindo a aleatorização do lado da mandíbula. Serão avaliados desgaste das próteses e dos antagonistas por meio de microscopia eletrônica de varredura; perda óssea periimplantar utilizando radiografias periapicais em três períodos, imediatamente após a instalação das próteses, uma semana após e três meses depois, percepção estética e alteração de cor utilizando o método de escala visual analógica pelo paciente. As hipóteses deste estudo são resistência à fratura e lascamento será semelhante nos grupos avaliados, todos os grupos serão esticamente aceitáveis, o desgaste do antagonista e das próteses será semelhante entre os grupos e a manutenção periodontal e nível de perda óssea será semelhante para os grupos(AU)

The pure ceramic crowns have been gaining strength in dentistry since the aesthetic and mechanical requirements are increasingly evident. Since free metal dentures of the bilayer type, not infrequently, show sputtering of the ceramic cover as the main long-term failure, the use of monolithic prostheses was started. At the same time, the search for and use of osseointegratable implants to support partial rehabilitation is increasing, being the first option for oral rehabilitation of edentulous areas. Therefore, the purpose of this prospective, randomized, split-mouth clinical study is to assess clinical performance and predictability, characterizing the number and type of early complications and failures such as antagonist wear, bone loss, gingival inflammation, and mechanical failures that may occur in PPFs of three implant - supported elements with mixed retention in posterior region of mandible in monolithic zirconia, zirconia infrastructure with covering ceramics and metaloceramics, besides evaluating aesthetic perception and patient satisfaction with each one. Patients selected (n = 8) will undergo surgical procedures to install two implants in the posterior mandible, two on each side. After three to four months the healing will be installed and the molding will be performed to make the prosthesis following the randomization of both the patients and the side of the jaw. Wear of prostheses and antagonists will be assessed by scanning electron microscopy and profilometry; bone loss peri-implant using periapical radiographs in seven periods, immediately after the implant installation, 7 days after surgery, before the installation of the healers, at the installation of the prosthesis, 21 days after, six and twelve months later, aesthetic perception and color change using the method of visual analog scale by the patient and an intraoral spectophotometer. The hypotheses of this study are resistance to fracture and chipping will be similar in the evaluated groups, all groups will be ethically acceptable, the wear of the antagonist and the prostheses will be similar between groups and the periodontal maintenance and level of bone loss will be similar for the groups(AU)

Screwed and cement implant prosthesis: current clinical considerations / Prótese sobre implante cimentada e parafusada: considerações clínicas atuais

ABSTRACT Introduction: There is no consensus as to which cemented or screwed retention system is best to avoid bone loss around the implant from a fixed implant-supported restoration. Objective: To evaluate the prosthesis retention systems on screw and cemented implants, regarding: bone loss, survival and failure rate, biological complications and microbiological analysis. Methods: A search was made for scientific articles that contemplated the subject through the databases Pubmed and SciELO, without period restriction. The titles, abstracts and then access to the full text has been verified. Results: It was found that excess cement may play an important role in the development of peri-implant disease. Technical failures are most seen in prosthesis retained by screws, and biological complications in cemented crowns. The success rate for both restraint systems is high, and retention-independent implant prosthesis treatment provides predictability. Conclusion: The appropriate retention system for the patient depends on several factors, including indication, advantages and disadvantages, retention provided, aesthetics and clinical performance.

RESUMO Introdução: Não há consenso sobre qual sistema de retenção, cimentado ou parafusado, é o melhor para evitar perda óssea ao redor do implante de uma restauração fixa implanto-suportada. Objetivo: Avaliar os sistemas de retenção de próteses sobre implantes parafusadas e cimentadas, quanto aos fatores: perda óssea, taxa de sobrevivência e de falhas, complicações biológicas e análises microbiológicas. Métodos: Foi realizada uma busca por artigos científicos que contemplassem o tema através das bases de dados Pubmed e SciELO, sem restrição de período. Os títulos, resumos e em seguida o acesso ao texto completo foi verificado. Resultados: Foi observado que o excesso de cimento pode desempenhar um papel importante no desenvolvimento da doença peri-implantar. Falhas técnicas são mais observadas em próteses retidas por parafusos e complicações biológicas em coroas cimentadas. A taxa de sucesso para os dois sistemas de retenção é alta e o tratamento com próteses sobre implantes independente da retenção oferece previsibilidade ao caso. Conclusão: O sistema de retenção apropriado para o paciente depende de diversos fatores, incluindo a indicação, vantagens e desvantagens, retenção fornecida, estética e desempenho clínico.

Efeitos da ciclagem mecânica, técnica de confecção e diferentes cerâmicas sobre a adaptação marginal e resistência à fratura de próteses implantossuportadas / Effects of mechanical cycling, manufacturing technique and ceramics types on the marginal fit and fracture resistance of implant-supported prostheses

O objetivo desse estudo in vitro foi avaliar por meio da metodologia de ciclagem mecânica a adaptação marginal (vertical/horizontal) e resistência à fratura, verificando a decorrência e possíveis complicações protéticas de próteses parafusadas implantossuportadas (hexágono externo) confeccionadas por diferentes técnicas e materiais cerâmicos. Foram confeccionados 50 corpos de prova, pela técnica convencional e Computer aided design and Computer aided manufacturing (CAD-CAM) divididos em cinco grupos (n=10 por grupo) sendo MC (Metalocerâmica); ZrL (Coping fresado em zircônia com link mais aplicação de cerâmica feldspática); Zr (Coping fresado em zircônia mais aplicação de cerâmica feldspática); MZrL (Monolítica de zircônia com link); MZr (Monolítica de zircônia), os quais foram submetidos à ciclagem mecânica em uma angulação de 30°, a 37°C e submetidos a 5 x 106 ciclos com aplicação de carga de 150N a uma frequência de 2,0Hz. No capítulo 1 foram avaliados à adaptação marginal vertical e horizontal (µm) antes e após ciclagem mecânica em Microscópio Óptico Tridimensional (3D) e no capítulo 2 os padrões de falhas das cerâmicas em Estereomicroscópio e Microscópio eletrônico de varredura (MEV) pós ciclagem mecânica. Os dados quantitativos foram analisados quanto a distribuição de normalidade e adotou-se o teste mais adequado considerando o nível de significância de 0,05. Os resultados obtidos para o capítulo 1 foram que em relação a desadaptação marginal vertical antes da ciclagem mecânica (tempo inicial-T0), houve diferença significativa com maiores valores de desadaptação para MC (93,93±22,84µm) e MZrL (66,12±11,87µm), p<0.05, quando comparados à Zr (49,92±3µm) e MZr (49,76±3,9µm), unindo os grupos com (ZrL+MZrL: 63,04±9,33µm) e sem link (Zr+MZr: 49,84±3,38µm) comparados ao grupo controle (MC) houve diferença significativa entre todos os grupos, p< 0.05, com menores valores de desadaptação para o grupo sem link. Em termos de desadaptação marginal horizontal antes da ciclagem mecânica (tempo inicial - To), houve diferença significativa com maiores valores de desadaptação para o grupo MC (-130,275±34,97µm), p<0.05, e menores valores de desadaptação para o grupo MZr (- 10,35±23,14µm), p<0.05, quando comparados aos demais grupos, além disso para o grupo sem link (Zr: -70,27±22,61µ vs MZr: -10,35±23,14µ), houve diferença significativa (p<0.05) com menores valores de desadaptação para MZr. Unindo os grupos com (-75,98±14,17µm) e sem link (-40,31±37,73µm), foi identificada diferença significativa entre todos os grupos quando comparados ao controle (MC: -130,27±34,97µm), (p< 0.001), com menores valores para o grupo sem link. Em relação à comparação antes e após ciclagem (Tf-T0), para análise da adaptação marginal vertical, o grupo MC (10,05±5,74µm) foi o que apresentou maiores valores de desadaptação, p<0.05, quando comparado aos demais grupos, já para análise da adaptação marginal horizontal, o grupo Zr (3±13,97µm) apresentou diferença estatística, p<0.05, na comparação com ZrL (-4,48±13,59µm) e MZrL (-2,825±11,81µm), unindo os grupos com (- 3,65±12,72µm) e sem link (0,35±10,99µm), houve menores valores de desadaptação para o grupo sem link, p<0.05. Para o capítulo 2, um total de 14 amostras falharam (lascamento/fratura de cerâmica). Os grupos MZrL e MZr apresentaram significativamente menor associação de falhas, com apenas uma falha (MZr) (p=0.035), assim como em relação ao tipo de substrato, os grupos MZrL e MZr apresentaram menos falhas (p=0,011). O uso de links e o número de ciclos não indicaram diferenças significativas entre os grupos (p≥0,05). Para área da falha, houve diferença significativa para o grupo Zr (15,55m²), p=0,029, apresentando maior extensão de área quando comparado aos demais. Em relação ao local da falha o grupo MC apresentou uma maior quantidade de falhas, com 5 falhas na região de orifício do parafuso quando comparado aos demais (p=0,043), os quais apresentaram falhas em diferentes locais. Portanto, o uso da tecnologia CAD/CAM foi o que resultou em menores valores de desadaptação marginal vertical e horizontal, assim como para resistência à fratura com destaque para as coroas monolíticas de zircônia(AU)

The aim of this in vitro study was to evaluate, through the mechanical cycling methodology, the marginal fit (vertical / horizontal) and fracture resistance, verifying the outcome and possible prosthetic complications of screwed-retained prostheses (external hexagon) made by different techniques and ceramic materials. Fifty specimens were made using the conventional technique and Computer aided design and Computer aided manufacturing (CAD-CAM) divided into five groups (n = 10 per group) being MC (Metal-ceramics crowns); ZrL (Coping milled in zirconia with link and covered feldspar ceramic); Zr (Coping milled in zirconia with covered feldspar ceramic); MZrL (Monolithic zirconia with link); MZr (Monolithic zirconia), which were subjected to mechanical cycling at an angle of 30 °, at 37 ° C and subjected to 5 x 106 cycles with a 150N load application at a frequency of 2.0Hz. In chapter 1, the vertical and horizontal marginal fit (µm) were evaluated before and after mechanical cycling under a threedimensional optical microscope (3D) and in chapter 2 the failure modes by the stereomicroscope and scanning electron microscope (SEM) after mechanical cycling. Quantitative data were analyzed for normality distribution and the most appropriate statistical test was adopted considering the significance level of 0.05. The results obtained for chapter 1 were that in relation to vertical marginal misfit before mechanical cycling (initial time-T0), there was a significant difference with higher misfit values for MC (93.93 ± 22.84µm) and MZrL (66, 12 ± 11.87µm), p <0.05, when compared to Zr (49.92 ± 3µm) and MZr (49.76 ± 3.9µm), joining the groups with (ZrL + MZrL: 63.04 ± 9.33µm) and without link (Zr + MZr: 49.84 ± 3.38µm) compared to the control group (MC) there was a significant difference between all groups, p<0.05, with lower misfit values for the group without link. In terms of horizontal marginal misfit before to mechanical cycling (initial time - To), there was a significant difference with higher misfit values for the MC group (-130.275 ± 34.97µm), p<0.05, and lower misfit values for the group MZr (-10.35 ± 23.14µm), p < 0.05, when compared to the other groups, in addition for the group without a link (Zr: -70.27 ± 22.61µm vs MZr: -10.35 ± 23, 14µm), there was a significant difference (p< 0.05) with lower misfit values for MZr. Joining the groups with (-75.98 ± 14.17µm) and without link (-40.31 ± 37.73µm), a significant difference was identified between all groups when compared to the control (MC: -130.27 ± 34, 97µm), (p<0.001), with lower values for the group without a link. Regarding the comparison before and after cycling (Tf-T0), for analysis of vertical marginal fit, the MC group (10.05 ± 5.74µm) was the one with the highest misfit values, p <0.05, when compared to the others groups, already for analysis of the horizontal marginal adaptation, the Zr group (3 ± 13.97µm) showed statistical difference, p <0.05. For chapter 2, a total of 14 samples failed, the groups MZrL and MZr showed significantly less association of failures, with only one failure (MZr), p = 0.035, as well as in relation to the type of substrate, the groups MZrL and MZr showed fewer failures (p = 0.011). The use of links and the number of cycles did not indicate significant differences between the groups (p≥0.05). For the chipping and/or fracture dimensions, there was a significant difference for the Zr group (p = 0.029) presenting a larger area of chipping when compared to the others. Regarding the location of the failure, the MC group showed a greater number of chipping in the screw orifice region when compared to the others (p = 0.043), which failed in different locations. Therefore, the use of the CAD / CAM system resulted in lower values of vertical and horizontal marginal maladjustment, as well as fracture resistance, with emphasis on monolithic crowns(AU)

Three-dimensional finite element analysis of four-implants supported mandibular overdentures using two different attachments / 中华口腔医学杂志

Objective@#To compare the biomechanical characteristics of four-implants mandibular overdentures supported by Locator attachment or bar-clip attachment under different mechanical loads using three-dimensional finite element analysis method.@*Methods@#Two different models of four-implants supported mandibular overdentures using Locator attachment and bar-clip attachment (hereinafter called Locator model and bar-clip model) were established. Each model was subjected to five different mechanical loading conditions: 100 N vertical loading in central incisor (vertical load of incisor), 100 N vertical loading or oblique loading in canine (vertical or oblique loads of canines), 100 N vertical or oblique loading in mandibular first molar (vertical or oblique loads of mandibular first molar). The stress distributions in implants, peri-implant bone and mucosa were recorded under the above five conditions to evaluate the effects of different attachments on the biomechanical properties of implant-supported mandibular overdentures.@*Results@#Regardless of loading conditions and types of attachments, the stress concentration in implants were located at the neck of implants, and the stress concentration in peri-implant bone was located in the cortical bone. The stress values in mucosa were always much smaller than those in implants and cortical bone. Regardless of loading positions (on canine or on mandibular first molar), the maximum stress at the bone interface around the implant under lateral loading was much higher than that under vertical loading. Under various loading conditions, the stress in implants and cortical bone of the Locator model (the highest von Mise stress value was respectively 79.5 and 22.3 MPa) were lower than that of bar-clip model (the highest von Mise stress value was 110.3 and 28.7 MPa respectively) while the maximum compressive stress in mucosa (0.198 MPa) in Locator model was slightly higher than that in the bar-clip model (0.137 MPa).@*Conclusions@#In clinical practice, the lateral force applied to the implant-retained overdenture should be minimized to avoid complications caused by pathological loads. Under the same loading condition, the stress distributions in overdenture using Locator attachment are more dispersed, which is more conducive to long-term stability of implants.

Comparison between open and closed-tray impression techniques on the implant transfer accuracy / Comparação das técnicas de moldagem com moldeira aberta e fechada na precisão da transferência de implantes

Objective: This in vitro study aimed to determine and compare the dimensional accuracy of open and closed-tray impression techniques for implantsupported prosthesis. Material and Methods: On a edentulous master model, four external hexagonal implants were parallelly installed and associated with four multi unit coping transfers and four multi unit rotational caps. A master superstructure was constructed and splinted all implants (control group). Five customized trays were constructed to perform ten open (n=5) and closed-tray (n=5) impressions. The obtained models were submitted to the dimensional analysis on three points in the center of the labial face of each implant (A, B, C, and D) with the aid of Stereoscopic Magnifying Glass with x60 magnification. The vertical misfit between the metallic structure and the implant analogues was measured on each point. The obtained results were submitted to Dixon's normality test and KruskalWallis test for independent samples p < 0.05) with the aid of Bioestat 5.0 software. Results: The means and standard deviation were: open tray technique ­ 24.6474 ± 14.8883 µm; closed-tray technique ­ 26.2257 ± 9.7421 µm; and control group 22.445 ± 7.7106 µm. Conclusion: The accuracy of open and closed-tray impression techniques showed no statistically significant differences and both techniques were effective for implant transfer. (AU)

Objetivos: O presente estudo in vitro objetiva determinar e comparar a precisão dimensional das técnicas de transferência de implantes direta e indireta para próteses implantossuportadas. Material e Métodos: a partir de um modelo mestre mandibular desdentado, foram instalados paralelamente quatro implantes hexágonos externos associados a quatro componentes multi unit e quatro capas multi unit rotacionais. Confeccionou-se uma infraestrutura mestre metálica unindo todos os elementos, considerando o conjunto como grupo controle (GC). Ao todo, fabricaram-se cinco moldeiras individuais para realizar 10 moldagens mediante as técnicas direta e indireta (n= 5), sendo os modelos obtidos submetidos à análise dimensional e estatística. Com uma lupa estereoscópica binocular com ampliação de 60 x, estabeleceram-se três pontos no centro da face vestibular de cada um dos implantes (A, B, C e D) por amostra. Em cada ponto, mensurou-se o desajuste vertical entre a estrutura metálica e os análogos. Os resultados obtidos foram submetidos ao teste de normalidade de Dixon e teste de Kruskal- Wallis para amostras independentes (p< 0,05) com o auxílio do software Bioestat 5.0. Resultados: médias aritméticas e desvio padrão identificados no grupo moldagem direta (24,6474 ± 14,8883 µm) e moldagem indireta (26,2257 ± 9,7421 µm) em comparação com o modelo mestre (22,445 ± 7,7106 µm). Conclusão: Pôde-se concluir que não houve diferenças estatísticas significativas entre as técnicas na precisão da transferência de implantes, sendo ambas igualmente eficientes. (AU)

Avaliação da força de mordida em pacientes com restaurações sobre implantes: prótese total bimaxilar versus prótese total inferior/convencional superior / Bite force evaluation on patients implant-supported restorations: complete maxillary/ mandibular prosthesis vs. mandibular fi xed prosthesis/conventional maxillary denture

Objetivo: avaliar a força de mordida (FM) em pacientes com próteses sobre implantes. Material e métodos: neste estudo transversal, os pacientes foram recrutados entre junho e setembro de 2015. Foram selecionados indivíduos maiores de 18 anos e de ambos os sexos, portadores de reabilitação protética osseointegrada total parafusada, com período pós-operatório de seis meses e 12 meses, divididos em G1 (próteses bimaxilares sobre implantes) e G2 (prótese total inferior/convencional superior). Os pacientes foram instruídos para que mordessem durante dez segundos com o máximo da força possível em um dinamômetro digital. As medidas foram realizadas na face oclusal dos primeiros molares inferiores em ambos os lados, um de cada vez, e na região dos incisivos. Cada local foi mensurado três vezes e obtida uma média dos valores, com precisão de 0,01 N. Entre cada local de medida, respeitou-se um intervalo de dois minutos. Ainda, a dor (EAV), abertura bucal (mm) e a qualidade de vida (OHIP-14) foram mensuradas. Resultados: a dor no G1 foi 0, enquanto no G2 foi grau 3. Não houve diferença para o grau de abertura bucal (47,5 mm x 39,5 mm). As queixas (dor física, desconforto e incapacidade) foram registradas apenas no G2, sem diferença estatística). Entretanto, houve uma diferença signifi cativa entre G1 (275,80 N) e G2 (63,38 N) para a FM somente no lado direito (p=0,025). Conclusão: pacientes com próteses bimaxilares apresentam melhores escores em todos os parâmetros avaliados. Entretanto, mais estudos devem ser realizados em função das amostras serem reduzidas neste ensaio.

Objective: to evaluate the bite force (BF) in patients with dental implants. Material and methods: in this cross-sectional study, patients were recruited between June and September 2015. Individuals older than 18 years-old and of both sexes, who underwent osseointegrated prosthetic rehabilitations within a 6-12-month postoperative period, were divided in G1 (bimaxillary protheses) and G2 (total, implant-supported mandibular/conventional maxillary denture). Patients were instructed to bite for ten seconds with as much force as possible on a digital dynamometer. Measurements were made on the occlusal face of the fi rst lower molars on both sides, separately, and also in the incisor region. Each site was measured 3 times and an average was obtained with an accuracy of 0.01 N. Between each measurement site, an interval of two minutes was respected. Still, pain (VAS), buccal opening (mm), and quality of life (OHIP-14) were registered. Results: pain levels for G1 were 0 while in G2 a grade 3 was scored. There was no difference for the degree of buccal opening (47.5 x 39.5 mm). Complaints (physical pain, discomfort, and disability) were recorded only in G2, but without statistical difference. However, there was a signifi cant difference between G1 (275.80 N) and G2 (63.38 N) for BF only at the right side (p=0.025). Conclusion: patients with bimaxillary prostheses presented better scores for all tested parameters. However, further studies should be performed since sample sizes were reduced in this trial.

Esplintagem em próteses implantossuportadas: revisão de literatura / Splinting in implant-supported prostheses: literature review

A distribuição da carga oclusal na interface osso/implante é um fator de sucesso a longo prazo dos implantes, o objetivo da esplintagem dos implantes é aumentar a resistência da unidade esplintada e minimizar a transferência da carga horizontal à interface osso/ implante, aumentando a área de superfície óssea. O propósito do deste estudo foi realizar uma revisão de literatura sobre a esplintagem das próteses implantossuportadas, a fim de discutir o comportamento biomecânico, vantagens e desvantagens das próteses esplintadas. Para a identificação dos estudos deste trabalho foi realizada uma estratégia de busca nas bases de dados PubMed, e LILACS, entre 2007 e maio 2017, utilizando os descritores: splinting, implant-supported prostheses, dental implant. Os critérios de inclusão foram: estudos clínicos, estudos in vitro, estudos prospectivos e retrospectivos, revisões de literatura e sistemáticas, relacionados ao tema proposto. Os critérios de exclusão foram: artigos cujo idioma não fosse o inglês ou português. Após a aplicação dos critérios de inclusão e exclusão 24 artigos foram analisados. Demostrou-se que: A maioria dos estudos in vitro analisados indicam a vantagem biomecânica da esplintagem dos implantes adjacentes, a fim de favorecer a distribuição das tensões na região periimplantar. A esplintagem de implantes curtos na região posterior teve um comportamento favorável tanto nos estudos clínicos quanto nos estudos in vitro, principalmente sob carregamento oblíquo. Os estudos clínicos ainda se mostram contraditórios em relação a conservação do nivel ósseo crestal. Entretanto, pesquisas têm apontado uma melhor efetividade da esplintagem na proporção coroa/implante sendo mais favorável para certas alturas da coroa(AU)

The stress distribution of the occlusal load at the bone/ implant interface is a factor for the long-term success of the implants, the goal of splinting implants is to increase the strength of the splinting unit and to minimize horizontal load transfer at the bone/implant interface, increasing the bone area. The purpose of this study was to perform a review of the literature on the splinted implant-supported in order to discuss the biomechanical behavior, advantages and disadvantages of the splinted prostheses. For the identification of the studies of this study, a search strategy was performed in PubMed and LILACS databases between 2007 and May 2017, using the descriptors: splinting, implant-supported prostheses, dental implant. The inclusion criteria were: clinical studies, in vitro studies, prospective and retrospective studies, literature reviews and systematic, related to the proposed theme. The exclusion criteria were: articles whose language was not English or Portuguese. After applying the inclusion and exclusion criteria, 24 articles were analyzed. It has been demonstrated that: Most of the in vitro studies analyzed indicate the biomechanical advantage of the splinting of the adjacent implants, in order to favor the distribution of the stress in the peri-implant region. The splinting of short implants in the posterior region had a favorable behavior both in clinical studies and in in vitro studies, especially under oblique loading. Clinical studies are still contradictory regarding preservation of the crestal bone level. However, research has indicated a better effectiveness of the splinting crown/implant ratio being more favorable for certain crown heights(AU)

A influência de dentaduras implanto-suportadas sobre o estado nutricional de indivíduos idosos / The influence of implant-supported dentures on the nutritional status of elderly individuals

RESUMO Objetivo: avaliar o estado nutricional de indivíduos idosos submetidos a procedimentos de reabilitação oral cirúrgico-protético. Métodos: foram avaliados 15 pacientes completamente edêntulos com idade igual ou superior a 60 anos (10 mulheres e 5 homens). Todos os indivíduos usaram prótese removível em ambos os arcos e tiveram suas próteses mandibulares substituídas por próteses com implante, foram submetidas à avaliação nutricional, compreendendo aspectos antropométricos, análise bioquímica do sangue e avaliação dietética antes da cirurgia e três e seis meses após a cirurgia. Resultados: a análise estatística da avaliação antropométrica não revelou diferença significativa entre os períodos de estudo, para todos os parâmetros investigados. A avaliação bioquímica revelou um aumento significativo da albumina três meses após o tratamento odontológico, voltando a níveis inferiores após seis meses. A avaliação dietética evidenciou que a ingestão calórica, macronutrientes proteínas e carboidratos não foram alterados após o tratamento odontológico. Por outro lado, a ingestão de lipídios foi menor seis meses após o tratamento odontológico em comparação com os resultados anteriores. Conclusão: portanto, a colocação de próteses dentárias completas implantadas nos idosos investigados neste estudo não modificou a condição nutricional no curto prazo, sugere que os sujeitos mantiveram as características alimentares anteriores.

ABSTRACT Purpose: the aim of this study was to evaluate the nutritional status of elderly individuals submitted to surgical-prosthetic oral rehabilitation procedures. Methods: fifteen patients completely edentulous aged 60 years or more were assessed (10 women and 5 men). All individuals wore removable dentures in both arches and had their mandibular dentures replaced by implant-supported prostheses, were submitted to nutritional evaluation comprising anthropometric aspects, biochemical blood analysis and dietary evaluation before surgery and at three and six months after surgery. Results: statistical analysis of the anthropometric evaluation did not reveal significant difference between the study periods, for all parameters investigated. The biochemical evaluation revealed a significant increase in albumin three months after dental treatment, returning to lower levels after six months. The dietary evaluation evidenced that the caloric intake, macronutrients proteins and carbohydrates was not altered after dental treatment. Conversely, the ingestion o lipids were lower six months after dental treatment compared to the previous results. Conclusion: therefore, the placement of implant-supported complete dentures in the elderly individuals investigated in this study did not modify the nutritional condition in the short term, suggests that the subjects maintained the previous dietary characteristics.

Avaliação clínica e radiográfica de implantes curtos: estudo retrospectivo no período de 7 anos / Clinical and radiographic evaluation of short implants: retrospective study for a period of 7 years

Áreas edêntulas com severa reabsorção óssea têm sido reabilitadas com próteses fixas instaladas sobre implantes curtos, evitando que os pacientes sejam submetidos a cirurgias de reconstrução óssea. Este estudo retrospectivo descreve o comportamento de implantes curtos avaliados em um período de 7 anos. A amostra foi composta por 70 pacientes, de ambos os gêneros, que receberam 136 implantes, de 6 ou 8mm de comprimento (Straumann® bone level e tissue level standard plus) sobre os quais foram instaladas próteses unitárias e múltiplas, cimentadas e parafusadas. Foram realizadas avaliações clínicas e radiográficas mensurando a estabilidade do implante por frequência de ressonância, perda óssea marginal por meio de radiografias panorâmicas, índices de placa e de sangramento marginal, taxas de sobrevivência do implante e da prótese. Dois implantes instalados na mandíbula foram perdidos, resultando em uma taxa de sobrevivência de 98,3%. A taxa de sobrevivência das próteses foi de 100%; a média de perda óssea foi de - 0,28mm; a estabilidade média dos implantes foi de 76,515 ISQ; as médias dos índices de placa e de sangramento foram de 32,83% e 33,21%, respectivamente. A estabilidade do implante foi maior na mandíbula que na maxila (p = 0,006). Os resultados obtidos nesta pesquisa, possibilitam afirmar que os implantes curtos podem ser utilizados com segurança dentro de suas indicações específicas.(AU)

Edentulous areas with severe bone resorption have been rehabilitated with fixed prostheses installed on short implants, avoiding surgeries of bone reconstruction. This retrospective study describes the behavior of short implants evaluated during 7 years. The sample consisted of 70 patients, of both genders, who received 136 implants, 6 or 8mm in length (Straumann® bone level and tissue level standard plus) on which single and multiple, cemented and screwed prostheses were installed. Clinical and radiographic evaluations were performed by measuring implant stability by resonance frequency, marginal bone loss by panoramic radiographs, plaque and marginal bleeding rates, the implant and prostheses survival rates. Two implants installed in mandible were lost, resulting in a survival rate of 98,3%. The prostheses survival rate was 100%; mean bone loss was -0,28mm; mean implants stability was 76,52 ISQ; mean plaque and bleeding indexes were 32,83% and 33,21%, respectively. The implant stability was higher in the mandible than in the maxilla (p = 0.006). The results obtained in this research make it possible to state that short implants can be used safely within their specific indications.(AU)

Removable Partial Denture Using Anterior Implant-Supported Fixed Prostheses for Edentulous Patients: A Case Report

This case study was to report the possible increase in the denture retention and psychological relief using the implant-supported fixed prostheses in a completely edentulous patient. The implants were placed in the anterior portion of the mandible in a patient who had completely edentulous state following the extraction of residual abutment teeth, and consequently a distal extension removable partial denture was fabricated. The patient's adaptation and satisfaction to the new prosthesis was monitored and confirmed in terms of masticatory function and esthetics, by restoring the oral condition similar to initial status before the residual teeth extraction. After 6 months, radiographic examination confirmed that both the abutment teeth and the implants were stable and well maintained. Considering the relatively short clinical follow-up period, however, continuous long-term monitoring was required.

Observation of the effect of orthodontic combined with implant denture in the treatment of single tooth loss / 中国基层医药

Objective To observe the clinical effect of combined treatment of single tooth loss and implant denture.Methods The clinical data of 80 patients with single tooth loss were analyzed retrospectively.According to the different surgical methods,they were randomly divided into control group and observation group,40 cases in each group.The control group was treated with implant denture,the observation group was treated with orthodontic treat-ment.The clinical efficacy of the two groups was observed.Results The total effective rate of the observation group was 97.50%,which was significantly higher than 62.50% of the control group(χ2 =15.31,P <0.05).The satisfac-tion scores of the observation group were higher than those of the control group,the differences were statistically signif-icant(t =12.21,17.78,15.98,11.85,9.35,all P <0.05).Conclusion The clinical effect of combined treatment of orthodontic and dental implants for patients with single tooth loss is remarkable,and can achieve good results,and improve the treatment satisfaction,it is worth promoting.

Clinical aspects in the treatment planning for rehabilitation with overdenture and protocol-type prosthesis / Aspectos clínicos utilizados no planejamento de prótese overdenture e protocolo

Objective: The aim of this study was to criticaly review the published literature regarding the clinical aspects involved in the rehabilitation of edentulous patients using Branemark protocol and overdenture prostheses.Methods: An active search was conducted in the LILACS, MEDLINE, PubMed, and SciELO databases using the descriptors: "Coating for dentures" (Overlay Prosthesis and Overdenture) and "Implant-supported fixed dental prosthesis" (Protesis dental de suporte implantado, Dental prosthesis, and Implant Supported Prosthesis) in Portuguese, English, and Spanish between January 2000 and October 2014.Results: The following parameters should be considered when selecting between Branemark protocol and overdenture prostheses: bone support, lip support, lip-line, upper lip length, oral mucosa conditions and size, alveolar ridge contour, crown-bone ratio, interarch space, and speaking space. Overdenture rehabilitation can provide many benefits to patients, such as prosthetic retention, stability, comfort, and improved aesthetics.Conclusions: This study highlights the need for a thorough individualized treatment planning to ensure that fixed prostheses and overdentures have an excellent prognosis when used appropriately in suitable patients at the appropriate time.

Objetivo: Verificar por meio de revisão crítica da literatura os aspectos clínicos durante o planejamento de pacientes edêntulos frente à utilização de próteses tipo protocolo de Branemark e overdenture.Métodos: Busca ativa nas bases de dados LILACS, MEDLINE, PubMed e SciELO por meio dos descritores: "Revestimento de dentadura" (Prótese de Recobrimento e Overdenture) e "Prótese dentária fixada por implante" (Protesis dental de suporte implantado e Dental prosthesis, implant supported) entre janeiro de 2000 até outubro de 2014 nas línguas Portuguesa, Inglesa e Espanhola.Resultados: Deve-se levar em consideração para indicar as próteses overdentures e protocolo o suporte ósseo, suporte labial, linha do sorriso, comprimento do lábio superior, qualidade e quantidade da mucosa, contorno do rebordo alveolar, relação coroa/osso, espaço interarcos e zona fonética. A reabilitação com overdenture pode trazer muitos benefícios ao paciente, tais como retenção, estabilidade, conforto, e a estética.Conclusões: Evidencia-se a necessidade de um planejamento individualizado, para que se chegue a um correto plano de tratamento, no qual as próteses fixas e overdentures possam ter um excelente prognóstico, desde que utilizadas no momento apropriado e no paciente indicado.

Failure of prosthetic screws on 971 implants

Abstract Aim: To evaluate the presence of failures in prosthetic screws and whether these failures are related to the type of prosthesis, abutment angulation and presence or not of intermediate. Methods: Two-hundred and sixty-seven patients were evaluated at the Federal University of Santa Catarina, totaling 971 external hexagonal implants in place for at least one year. A Tobit regression model for censored variables was used and the explanatory variables were subjected to percentage analysis. Results: The results demonstrated a relationship between the failure in prosthetic screws and the investigated factors with a significance of F=0.003 and p<0.05. The percentage analysis showed that the prosthetic screw failed in 8.82% of 238 unitary prostheses and 10.1% of 773 multiple prostheses. Among 912 abutments, 9.43% failed and in the 59 angled abutments, failures appeared in 15.25%. A total of 200 prostheses were placed over the implant platform and 13% failed. A total of 771 prostheses were made over abutment and 8.95% of these screws failed. Conclusions: Through multiple linear regression it could be concluded that the type of prosthesis showed no significant influence on the prosthetic screw failure, but other variables were related to this mechanical failure. There was a significant relationship among the variables, demonstrating the need for greater attention in choosing the type of prosthesis, the abutment angulation and whether the prosthesis will be placed directly on the implant platform or on the abutment.

Parafusamento transverso em prótese sobre implante: aspectos inovadores no design e na aplicação do sistema / Cross-pinning in implant-supported prosthesis: innovative design and approach

Reabilitações com próteses implantossuportadas são usadas frequentemente para resolver casos de edentulismo. Elas podem ser retidas por de meio de parafusos ou agentes de cimentação. No entanto, nos casos de alinhamento inadequado dos implantes ou fragilidade pelo desenho final da estrutura protética, o sistema de parafusamento convencional não pode ser utilizado. Um método alternativo para se manter a reversibilidade da peça protética é o parafusamento transverso. Este consiste em um sistema tubo/parafuso de dimensões reduzidas que possibilita o parafusamento em uma área palatina ou lingual. Entretanto, aperfeiçoamentos nos sistemas existentes comercialmente eram necessários para se suprirem dificuldades como custo, técnica de confecção e dimensões dos componentes. O presente artigo apresenta o desenvolvimento de um produto adequado para este método, para suprir as desvantagens dos sistemas anteriores, apresenta a técnica de confecção clínica e laboratorial, e discute os aspectos fundamentais no planejamento desse sistema...

Implant-supported prostheses are frequently used in oral rehabilitation to solve cases of edentulism. They may be screw-retained or cement-retained. However, sometimes conventional screw-retained systems can not be used in cases of improper alignment of implants or compromised structural integrity of the prosthesis. An alternative method to maintain reversibility of the rehabilitation is cross-pinning. This system consists of a tube/screw with reduced dimensions which enables screwing in a palatal or lingual area. However, improvements in the commercially existing systems have been necessary to overcome difficulties such as costs, manufacturing technique and component dimensions. This paper presents the development of an appropriate product for this method, allowing to overcome the disadvantages of previous systems and analyzes the clinical and laboratory steps discussing the fundamental aspects of planning when using this system...