Browsing by Author "Ferreira, Paula"
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- Antibacterial effect of silver diamine fluoride incorporated in fissure sealantsPublication . Veiga, Nélio; Ferreira, Paula; Correia, Tiago; Correia, Maria J.; Pereira, Carlos; Amaral, Odete; Correia, Ilídio J.Introduction: The application of fissure sealants is considered to be an important primary prevention method used in dental medicine. However, one of the most common reasons of dental caries development in teeth with fissure sealants is due to the formation of microleakages. The association between various dental biomaterials may limit the major disadvantages and limitations of biomaterials functioning in a complementary manner. The present study consists in the incorporation of a cariostatic agent – silver diamine fluoride (SDF) – in a resin-based fissure sealant followed by the study of release kinetics by spectrophotometry analysis of the association between both biomaterials and assessment of the inhibitory effect on the growth of the reference bacterial strain Streptococcus mutans (S. mutans) in an in vitro study. Materials and Methods: An experimental in vitro study was designed consisting in the entrapment of SDF (Cariestop® 12% and 30%) into a commercially available fissure sealant (Fissurit® ), by photopolymerization and photocrosslinking. The same sealant, without SDF was used as a negative control. The effect of the sealants on the growth of S. mutans was determined by the presence of bacterial inhibitory halos in the cultures at the end of the incubation period. In order to confirm the absence of bacteria in the surface of the materials, Scanning Electron Microscopy (SEM) characterization was performed. Also, to analyze the release profile of SDF along time, spectrophotometry technique was applied. Results: The obtained results indicate that the association of SDF to a resin-based fissure sealant may be able to increase the inhibition of S. mutans growth. However, no SDF release was noticed during the in vitro release studies and no statistical significant difference was verified when comparing the inhibitory halo sizes obtained for test and control group. Conclusions: In this study, the entrapment of SDF in the resin-based fissure sealant did not potentiate the antibacterial effect of the fissure sealant or avoid the immediate development of dental caries. The development of more laboratorial research and, afterwards, long-term clinical data are necessary in order to verify if this association between these biomaterials is effective and can be considered for being used in oral health management. Also, other methodologies for associating cariostatic agents and sealant should be addressed.
- Boosting through-plane electrical conductivity: chitosan composite films with carbon-sepiolite and multiwalled carbon nanotubesPublication . Barra, Ana; Ferreira, Nuno M.; Pocas, Fátima; Ruiz-Hitzky, Eduardo; Nunes, Cláudia; Ferreira, PaulaFlexible and electrically conductive materials are gaining significant attention across various domains, notably in electronics, biomedicine and food industry. One promising strategy involves the integration of electrically conductive nanostructures into a polymeric matrix to fabricate composite materials. However, achieving uniform through-plane electrical conductivity remains a challenge due to the preferential alignment of carbon nanostructures in the in-plane direction. Herein, we report the development of electrically conductive chitosan (CS)- based biocomposite films incorporating a multicomponent filler system. By combining carbon supported on sepiolite clay (CARSEP) with multiwalled carbon nanotubes (MWCNT), it is aimed to facilitate an interconnected distribution in both in-plane and through-plane directions. The optimized film, featuring a CS/CARSEP/MWCNT mass ratio of 50/40/10, exhibited a maximum electrical conductivity of 55.5 S/m and 0.1 S/m in the in-plane and through-plane directions, respectively. Additionally, migration studies demonstrated the absence of harmful compounds upon heating the film up to 60 ◦C in air, ethanol, or hexane. These findings highlight the potential of these flexible and electrically conductive biocomposite films, primarily composed of biobased materials, for applications requiring through-plane electrical conductivity.
- Development of a bioluminescent reporter system to monitor neonatal Group B Streptococcal infectionPublication . Geraldo, Rafaela; Lorga, Inês; Ferreira, Paula; Oliveira, Liliana; Andrade, Elva Bonifácio
- Oral and gastric helicobacter pylori: effects and associationsPublication . Veiga, Nélio; Pereira, Carlos; Resende, Carlos; Amaral, Odete; Ferreira, Manuela; Nelas, Paula; Chaves, Claudia; Duarte, João; Cirnes, Luis; Machado, José Carlos; Ferreira, Paula; Correia, Ilídio J.Introduction This study consisted in the comparison of the prevalence of Helicobacter pylori (H. pylori) present in the stomach and in saliva of a sample of Portuguese adolescents and the assessment of the association between H. pylori infection with socio-demographic variables and prevalence of dental caries. Materials and Methods A cross-sectional study was designed including a sample of 447 adolescents aged 12 to 19 years old, attending a public school in Sátão, Portugal. A questionnaire about socio-demographic variables and oral health behaviors was applied. Gastric H. pylori infection was determined using the urease breath test (UBT). Saliva collection was obtained and DNA was extracted by Polymerase Chain Reaction (PCR) in order to detect the presence of oral H. pylori. Results The prevalence of gastric H. pylori detected by UBT was 35.9%. Within the adolescents with a gastric UBT positive, only 1.9% were positive for oral H. pylori. The presence of gastric H. pylori was found to be associated with age (>15years, Odds ratio(OR)=1.64,95% CI=1.08-2.52), residence area (urban,OR=1.48,95%CI=1.03-2.29) and parents' professional situation (unemployed,OR=1.22,95%CI=1.02-1.23). Among those with detected dental caries during the intra-oral observation, 37.4% were positive for gastric H. pylori and 40.2% negative for the same bacterial strain (p=0.3). Conclusions The oral cavity cannot be considered a reservoir for infection of H. pylori. Gastric H. pylori infection was found to be associated with socio-demographic variables such as age, residence area and socioeconomic status.
- Oral health behaviors in a sample of Portuguese adolescents: an educational issuePublication . Veiga, Nélio; Pereira, Carlos; Ferreira, Paula; Correia, Ilídio J.Introduction: Oral health education is an important issue that should be given to children and adolescents, allowing the acquisition of correct oral health behaviors. The objective of this study was to determine the prevalence of oral health behaviors among a sample of portuguese adolescents and verify the association with socio-demographic factors, in order to analyze the main needs related with oral health education to improve oral health status among adolescents. Methods: A cross-sectional study was designed with a sample of 447 adolescents aged 12 to 19 years old, attending a public school in Sátão, Portugal. A self-administered questionnaire was applied questioning about socio-demographic factors and oral health behaviors to each adolescent in the classroom. Prevalence was expressed in proportions and crude odds ratio (OR) with 95% confidence intervals (CI) were used to measure the strength of association between oral health behaviors and socio-demographic factors. Results: The prevalence of tooth brushing (twice-a-day or more) was 90.6%. Five point eight percent of adolescents reported daily flossing, more frequent among female gender (female, OR = 2.03, 95% CI = (1.35 to 3.05)) and adolescents older than 15 years (>15 years, OR = 1.90, 95% CI = (1.24 to 2.92)). Sixty-seven percent had at least one dental appointment in the previous twelve months. The prevalence of dental appointments was associated with the father’s professional situation (unemployed, OR = 0.33, 95% CI = (0.17 to 0.65)) and crowding index (>1, OR = 0.4, 95% CI = (0.16 to 0.98)). Thirty-two point nine percent of adolescents referred having at least one episode of dental pain during their lives. Conclusion: Considering the results of the present study that show the need of improvement of some aspects related with oral health among adolescents, oral health community programs and primary preventive strategies, such as improvement of oral health education in schools should be considered in order to reduce the risk level of oral diseases and develop better oral health behaviors.