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Browsing by Author "Fialho, Joana"

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  • Comparação estrutural de dois sistemas dinâmicos submetidos a torque progressivo
    Publication . Saramago, Catarina; Valentim, Bruno; Lopes, Hernâni; Fialho, Joana; Correia, André; Araújo, Filipe
    Objetivos: O objetivo deste estudo consistiu em comparar o torque máximo entre dois sistemas dinâmicos (BHS30® e UBH30® de 4 estrias) e caracterizar as falhas dos seus componentes (chaves de aperto e/ou parafusos). Materiais e métodos: De forma a testar o comportamento mecânico de dois sistemas dinâmicos, foi realizado um estudo experimental laboratorial. Três amostras de cada sistema foram submetidas a um torque progressivo, numa angulação de 30.º, até que ocorresse falha de um dos componentes (parafuso e/ou chave de aperto). De forma a garantir o correto cumprimento da angulação, foi desenhada e impressa uma guia de posicionamento. Um torquímetro digital foi utilizado para registar os valores obtidos e foi realizada uma análise estatística com recurso ao software SPSS®. Após a aplicação do torque máximo, cada amostra foi analisada com lupas de laboratório numa ampliação de 4x, 6x e 11x. Os valores médios obtidos para cada sistema dinâmico foram comparados e a significância estatística foi estabelecida em 0,05. Resultados: O sistema BHS30® foi aquele que apresentou um valor médio de torque máximo mais elevado (59 N.cm) comparativamente ao UBH30® (35,8 N.cm), sendo essa diferença estatisticamente significativa (p=0,007). De uma forma geral, e independentemente do sistema testado, os parafusos apresentaram deformações. Enquanto que nas amostras do sistema BHS30® essas deformações encontraram? se limitadas às secções em que existiu maior contacto com a chave de aperto, no sistema UBH30® de 4 estrias as falhas ocorreram de uma forma generalizada, levando inclusivamente à perda do formato original e impossibilitando o desaperto. Para além disso, em duas das amostras do sistema BHS30® ocorreu a fratura da cabeça do parafuso. Em relação às chaves de aperto, apenas foram visíveis deformações nas chaves do sistema BHS30®. Conclusões: Embora o valor máximo de torque recomendado pelo fabricante seja de 30 N.cm, é possível verificar que o sistema BHS30® consegue resistir a valores de torque mais elevados do que o sistema UBH30® de 4 estrias. O desenho da cabeça do parafuso parece ser fundamental na distribuição das tensões/ deformações.
    2021-01-07Journal article Open access Show more
  • Mechanical and surface properties of a 3D-printed dental resin reinforced with graphene
    Publication . Salgado, Helena; Fialho, Joana; Marques, Marco; Vaz, Mário; Figueiral, Maria Helena; Mesquita, Pedro
    Objectives: Commercial photocurable polymers used in dental additive manufacturing still have mechanical limitations. The incorporation of graphene may provide interesting advantages in this field. This study aimed to evaluate in vitro the effect of adding graphene nanoparticles to a 3D-printed polymethylmethacrylate dental resin in terms of surface roughness, flexural properties, and hardness. Methods: A 3D-printed dental resin (Dental Sand, Harz Lab) was loaded with four different graphene nanoplatelet (Graphenest) concentrations: 0.01wt%, 0.1wt%, 0.25wt%, and 0.5wt%. The neat resin was used as the control group. The surface roughness was measured with a contact profilometer using bar-shaped specimens (50x10x4mm). The flexural strength of specimens (80x10x4mm) from each group was calculated using the 3-point bending test in a Universal Test Machine. Hardness shore D was measured using a manual durometer on round-shaped specimens (12x6mm). Data were evaluated using the Kruskall-Wallis test followed by post-hoc Bonferroni corrected pairwise inter-group comparisons. Statistical significance was set at p<0.05. Results: Graphene improved 3D-printed PMMA resin hardness with statistical significance at a concentration of 0.01wt% (p=0.043). Surface roughness increased with graphene concentrations above 0.01wt%, with statistically significant differences at 0.25wt% (p=0.006) and 0.5wt% (p=0.005) concentrations. Flexural properties worsened with increased graphene concentrations, and these differences were significant in the concentrations of 0.25wt% (p=0.028) and 0.5wt% (p=0.006). Conclusions: The use of graphene as a mechanical reinforcement nanomaterial seems to be viable at low concentrations without prejudice to the surface roughness of a 3D-printed polymethylmethacrylate resin. (Rev Port Estomatol Med Dent Cir Maxilofac.
    2023-03-31Journal article Open access Show more
  • A new digital evaluation protocol applied in a retrospective analysis of periodontal plastic surgery of gingival recessions
    Publication . Marques, Tiago; N. M., Santos; Fialho, Joana; Montero, J.; Correia, A.
    This research aimed to develop a new digital evaluation protocol to objectively quantify the volumetric changes of root coverage periodontal plastic surgery when combined with connective tissue graft. Consecutive patients with Cairo recession type 1 (RT1) or Cairo recession type 2 (RT2) were treated. Accurate study models obtained at baseline and follow-ups were optically scanned. Healing dynamics were measured by calculating volume differences between time points. Nineteen patients were treated between December 2014 and January 2019. At 3-month follow-up, root coverage was 95.6% (± 14.5%) with tunnel and connective tissue graft (TUN + CTG) technique, and 88.9% (± 20.5%) with the vestibular incision subperiosteal tunnel access and connective tissue graft (VISTA + CTG) technique. Recession decreased 1.33 (± 0.86) mm and 1.42 (± 0.92) mm, respectively (p = 0.337). At 6-month follow-up, root coverage was 96.5% (± 10.4%) with the TUN + CTG and 93.9% (± 10.3%) with the VISTA + CTG. Recession decreased 1.35 (± 0.85) mm and 1.45 (± 0.82) mm, respectively (p = 0.455). Complete root coverage was achieved in 86.7% (± 0.4%) with TUN + CTG and 70.6% (± 0.5%) with VISTA + CTG. No statistically significant differences were found between techniques. The digital protocol presented proved to be a non-invasive technique for accurate measurements of clinical outcomes. Both techniques reduce gingival recessions, with no statistically significant differences.
    2021-10-14Journal article Open access Show more
  • Oral health behaviors and dental caries in a sample of Portuguese militaries
    Publication . Azevedo, Luís; Martins, David; Fialho, Joana; Veiga, Nélio; Correia, André
    Objectives: To determine the prevalence of dental caries and oral health behaviors in a sample of the Portuguese army. Methods: An observational cross-sectional study was conducted in a sample of army soldiers of the Infantry Regiment no. 14 of Viseu, Portugal, using a questionnaire. The study involved 122 members of the armed forces, who were asked to complete a questionnaire autonomously. The questionnaire enquired about general oral-health behaviors but focused mainly on: i) frequency of toothbrushing, ii) use of dental floss and iii) frequency of dental appointments. It also asked about sociodemographic information, like age and gender. An intra-oral observation was also conducted to determine the DMFT index and to record dental plaque based on the Silness and Löe plaque index (1964). Results: The prevalence of dental caries was high (51.6%±7.4%; DMFT of 4.6±3.5). The most prevalent score of the Silness and Löe plaque index was score 2 - visible plaque (58.2%). Regarding oral hygiene habits, most of the sample reported brushing their teeth at least twice a day (65.6%) and using fluoride toothpaste (64.8%). However, very few participants (18%) used dental floss. More than 30% of the participants had not visited a dentist within the previous year. Furthermore, 45.9% were current smokers. Conclusion: Prevention programs and promoting actions for oral health with these specific groups are important and should be adopted to reduce the prevalence of dental caries and to increases the knowledge about oral-health behaviors.
    2018Journal article Open access Show more
  • Oral health behaviors, dental injuries and mouthguard awareness among a sample of Portuguese athletes: a cross sectional study
    Publication . Azevedo, Luís; Martins, David Simões; Fialho, Joana; Veiga, Nélio; Correia, André; Fine, Peter
    Aim: To determine the oral health behaviors, the prevalence of dental injuries, the level of information about first-aid procedures in the case of dental avulsion and the mouthguard awareness in a sample of Portuguese athletes. Materials and Methods: Cross-sectional research among 1,048 athletes from the district of Viseu, Portugal. A self-administered questionnaire included demographic data and questions about: I) oral hygiene habits, II) occurrence of orofacial trauma, III) use of mouthguards and IV) athletes’ knowledge regarding first-aid management in case of dental avulsion was given. The comparison between different variables was made by Chi-square test with level of significant set at p-value =0.05. Results: The mean age of the sample (76.24% male) was 18.14±8.17 years. Overall, the results demonstrated a low use of dental floss (25.48%) and a high number of athletes (21.94%) that had not visited a dentist in more than a year. The prevalence of dental trauma was 5.06% and the most common dental injuries experienced by athletes were crown fractures (60.38%). Nearly half of the participants (45.23%) reported not knowing how to act following a dental avulsion. The rate of mouthguard use was very low (9.73%). There was a significant relationship between the prevalence of dental injuries and the use of mouthguards (p=0.000; Cramér’s V=0.145). Conclusion: The prevalence of dental trauma in our population was low. A low number of athletes use a mouthguard and there is a lack of knowledge concerning dental trauma issues. Prevention programs and promoting actions among this population are important and should be adopted.
    2019Journal article Open access Show more