Stress distribution of multiple implant-supported prostheses: Photoelastic and strain gauge analyses of external hexagon and morse taper connections.

Background: To evaluate the stress distribution of three-element prostheses on two different implant systems (External Hexagon (EH) or Morse Taper (MT)) and with two different retention mechanisms (screw-retained or cemented), by photoelastic analysis and strain gauge analyses. Material and Methods: Four photoelastic and 24 strain gauge models of a partially edentulous maxilla were made and were divided in four groups according to connection and retention system: Group I (EH-C) - external hexagon+cement-retained prosthesis; Group II (EH-S) external hexagon+screw-retained prosthesis; Group III (MT-C) - morse taper+cement-retained prosthesis; Group IV (MT-S) - morse taper+screw-retained prosthesis. The implants were installed in the axial position, the first in the region of element 15 and the distal implant in the region of element 17. Loads of 100 N were applied on the occlusal surface of the prosthesis for 10 seconds. For the photoelasticity analysis, photographic images were taken and were evaluated according to the number of high-intensity fringes. For the strain gauge analysis, the strain gauges were positioned on the marginal crest of the implants and on the apical region, being numbered for analysis of the stress distribution in each region. The electrical signals were captured and processed by specific software. Results: Higher concentration of tension was observed in the apical region of the implants and mainly in the distal implant, where the formation of fringes was higher. The microstrain values obtained for each group were similar: EH-C (454±18,3 µÉ›); EH-S (469±94 µÉ›); MT-C (466±49,8 µÉ›); MT-S (460±36,6 µÉ›). It was observed that apical position had higher stress concentrations for all analyzed groups. Conclusions: The different connections and fixation mode did not interfere in the amount of tension generated in the tissue adjacent to the implant, also the region that generated the greatest amount of tension was in the apical region of the anterior implant. Key words:Dental implants, biomechanics, fixed prosthodontics.

Comparison of the Morse Cone Connection with the Internal Hexagon and External Hexagon Connections Based on Microleakage - Review.

The gap formed at the abutment-implant interface brings about a bacterial colonization. In addition, a bacterial reservoir can be established within the implant. The build-up of microorganisms around the implant can cause soft tissue infections and bone loss around the implant, which can lead to implant failure. Our literature review aimed to evaluate the infiltration at the implant-abutment interface, comparing the Morse cone connection with the external hexagon and internal hexagon connections. A literature search using the PubMed database was performed on March 24, 2021. The search terms were combinations of "Morse cone" or "Morse taper" with each of the following terms (individually): "microleakage", "leakage", "infiltration", and "penetration". The inclusion criterion was in vitro studies comparing the Morse cone with the external hexagon and/or internal hexagon, based on infiltration at the implant-abutment interface. The exclusion criterion was the evaluation of microleakage at the implant-abutment interface after applying a sealant over this region. The search was expanded as needed. There was no limit on the year of publication, and only articles written in English were included. In addition, references cited in included articles were also included in this review when they were appropriate. This literature review concluded that, in most cases, the microleakage in the Morse cone connection was lower when compared with the external hexagon and internal hexagon connections.

Titanium versus ceramic implants for overdentures: a meta-analysis of prospective studies.

The aim of this study was to compare the use of titanium and ceramic implants for overdentures in terms of their failure rates, surface treatments, and marginal bone loss (MBL). The literature was searched using the PubMed, Scopus, and Cochrane databases up to October 2019. Clinical studies in which ceramic and titanium implants for overdentures were compared in terms of their failure rates, surface treatments, and MBL were included in the meta-analysis. The meta-analysis was performed based on the Mantel-Haenszel and inverse variance methods using a fixed-effects model and 95% confidence intervals. A total of 2747 publications were identified after the exclusion of duplicate articles. Fifteen were selected for full-text reading, and 2 were included in the review. Each of the 2 studies initially enrolled 24 patients, and a total of 38 patients (mean age of 62 years) were evaluated at the 1-year follow-up. A total of 112 titanium implants (success rate of 71.1%) and 146 ceramic implants (success rate of 65.9%) were placed. Twenty titanium implants failed, and an associated MBL of 0.15 mm was observed. For ceramic implants, 42 failures occurred, and an associated MBL of 0.33 mm was observed. Titanium implants provided better clinical results (less MBL and lower failure rate) for the support of overdentures than did ceramic implants.

Síndrome da apneia obstrutiva do sono em crianças (SAOS) associada aos dispositivos ortopédicos orais hyrax e bionator de balters sobre respostas miofuncionais / Obstructive sleep apnea syndrome in children (OSAS) associated with Hyrax and Balters' Bionator oral orthopedic devices on myofunctional responses

O objetivo deste estudo foi avaliar a influência terapêutica dos dispositivos orais Hyrax e Bionator de Balters no tratamento da Síndrome da Apneia Obstrutiva do Sono (SAOS), sobre a melhora da SAOS observado pela polissonografia, atividade elétrica dos músculos masseter e temporal, força máxima de mordida, qualidade de vida, e diâmetro dos pontos cefalométricos. Foram selecionados 11 participantes de ambos os sexos, diagnosticados com SAOS através do exame polissonográfico tipo III e com necessidade de tratamento ortopédico facial. Foi feita a coleta dos dados, os responsáveis preencheram os questionários (Escala de Distúrbios do Sono em Crianças e OSA-18-PV), termo de consentimento livre e esclarecido aos responsáveis e para as crianças, documentação ortodôntica (incluindo a análise do diâmetro dos pontos cefalométricos - espaço nasofaríngeo anterior e posterior (NFA-NFP), assim como espaço bucofaríngeo anterior e posterior (BFA-BFP)), análises iniciais da eletromiografia dos músculos masseter e temporal e força máxima de mordida. Estas informações foram coletadas no início do tratamento e após 11 meses, assim como o exame polissonográfico tipo III. Os dados foram normalizados pelo apertamento com Parafilm M e submetidos à análise normalidade pelo teste de Kolmogorov-Smirnov, sendo observado os dados: valor de polissonografia; eletromiografia de masséter direito e esquerdo; eletromiografia de temporal direito e esquerdo; força de mordida em região de incisivo e molar esquerdo/direito, os questionários foram avaliados através de score e nota (0-10), e cefalometria (análise das distâncias NFA-NFP e BFABFP). Para estes dados, foi realizado o teste t de Student. Para os dados com distribuição não normal, foi realizado o teste de Wilcoxon. Todas as análises foram realizadas com nível de significância de 5%. Em relação ao exame polissonográfico e os questionários, houve diferença estatística evidenciando melhora na qualidade do sono dos indivíduos. A eletromiografia demonstrou que houve diferença estatística em repouso no músculo temporal direito, e na mastigação de uva passas, nos músculos masseter e temporal do lado direito. Na cefalometria, foi observada diferença estatística na distância entre os pontos NFA-NFP. Conclui-se que o uso dos dispositivos Hyrax e Bionator de Balters em crianças classe II e portadoras da SAOS é uma alternativa de tratamento segura e eficaz(AU)

The aim of the study was to evaluate the influence of oral devices Hyrax and Balters Bionator in the treatment of Obstructive Sleep Apnea Syndrome (OSAS), on the improvement of OSAS observed by polysomnography, electrical activity of the masseter and temporal muscles, maximum bite force, quality of life, and diameter of cephalometric points. Eleven participants of both genders, diagnosed with OSAS through type III polysomnographic examination and in need of facial orthopedic treatment, were selected. Data collection was performed, the guardians filled out the questionnaires (Sleep Disorders Scale in Children and OSA-18-PV), informed consent form to guardians and for children, cephalometric orthodontic documents - nasopharyngeal space anterior and posterior (NFA-NFP), as well as anterior and posterior buccopharyngeal space (BFA-BFP)), initial analysis of the electromyography of the masseter and temporal muscles and maximum bite force. This information was collected at the beginning of treatment and after 11 months, as well as the type III polysomnographic exam. Data were normalized by tightening with Parafilm M and analysis of normality using the Kolmogorov-Smirnov test, observing the following data: polysomnography value; right and left masseter electromyography; right and left temporal electromyography; bite force in the left/right incisor and molar region, the questionnaires were obtained through score and grade (0-10), and cephalometry (analysis of the NFA-NFP and BFA-BFP distances). For these data, the Student test was performed. For data with non-normal distribution, the Wilcoxon test was performed. All analyzes were performed with a significance level of 5%. Regarding the polysomnographic exam and the questionnaires, there was a statistical difference showing an improvement in the sleep quality of the respondents. The electromyography required that there was a statistical difference at rest in the right muscle, and when chewing raisins, in the masseter and temporal muscles on the right side. In cephalometry, a statistical difference was observed in the distance between the NFA-NFP points. It can be concluded that the use of the Balters Hyrax and Bionator devices in class II children and children with OSAS is a safe and effective treatment alternative(AU)