Influência da técnica de acabamento na estabilidade cromática dos bis-acrílicos

Tese de mestrado, Medicina Dentária, Universidade de Lisboa, Faculdade de Medicina Dentária, 2014Objetivo: Avaliar o efeito do tipo de polimento e do tempo de exposição a um corante na estabilidade cromática de duas resinas bis-acrílicas. Métodos: Foram preparados sessenta discos em resina bis-acrílica. Metade dos discos foram fabricados com Protemp 4 e a outra metade com Structur 3. As faces dos discos foram limpas com álcool e foram constituídos doze grupos experimentais (n=5) com base na utilização de diferentes métodos de polimento (sem tratamento adicional; escova de pelo de cabra; disco de grão grosso Sof-Lex seguido de escova de pelo de cabra; sequência de discos Sof-Lex; disco de grão grosso Sof-Lex seguido de aplicação de resina Fortify; disco de grão grosso Sof-Lex seguido de aplicação de Z-Prime Plus). Sessenta minutos após o polimento foi realizada a medição de cor inicial e os espécimes foram imersos em solução de café. Após 24 horas e 7 dias de imersão, foram realizadas novas medições dos parâmetros de cor. Para o registo da cor foram utilizados os parâmetros do sistema CIE L*a*b* e a diferença cromática foi calculada de acordo com a fórmula ΔE*=[(ΔL*)2+(Δa*)2+(Δb*)2]1/2. Os dados obtidos foram analisados com testes estatísticos não paramétricos de acordo com os métodos Kruskal-Wallis, Mann-Whitney e Wilcoxon (alfa=0,05). Resultados: Os valores da ΔE variaram entre 4,9 e 11,7 (24 horas) e 13,3 e 21,4 (7 dias). O aumento do tempo de imersão do bis-acrílico na solução de café conduziu a um aumento da ΔE (p<0,001). Às 24 horas, não se encontraram diferenças entre os materiais (p=0,941). Ao fim de 7 dias, o Protemp 4 mostrou valores da ΔE (p=0,032) inferiores aos obtidos com a Structur 3. Com exceção do Protemp 4 com 7 dias de imersão, a ΔE foi influenciada pelo método de polimento (p<0,05). Conclusão: Todos os espécimes apresentaram valores de ΔE considerados clinicamente inaceitáveis.Aim: To study the effect of several polishing techniques and time exposure to a staining agent on the colour stability of two bis-acrylic resins. Methods: Sixty cylindrical specimens of bis-acrylic were prepared, thirty with Protemp 4 and thirty with Strutur 3. Both sides of specimens were cleaned with alcohol and twelve groups were created (n=5) according to the surface treatment used (without any other treatment, goat hair brushes, Sof-Lex coarser grit disc followed by goat hair brushes, Sof-Lex sequence, Sof-Lex coarser grit disc with Fortify, Sof-Lex coarser grit disc with Z-Prime Plus). Sixty minutes after polishing, the baseline colour values were measured, and all the specimens were immersed in the staining solution (coffee). After 24 hours and 7 days additional measurements were taken. Colour changes were calculated according to the CIE L*a*b* colour scale, by the formula: ΔE*=[(ΔL*)2+(Δa*)2+(Δb*)2]1/2. All data were statistically analysed by non-parametric tests according to Kruskal-Wallis, Mann-Whitney and Wilcoxon methods (alpha=0.05). Results: ΔE mean values ranged between 4.9 and 11.7 after 24 hours of immersion and between 13.3 and 21.4 after 7 days. Increasing the immersion time in the staining solution led to an increase of ΔE values (p<0,001). After 24 hours of immersion, there were no statistical differences among materials (p=0.941). After 7 days of immersion, Protemp 4 obtained lower ΔE (p=0.032) than Structur 3. The ΔE was influenced by the polishing technique, except for Protemp 4 after 7 days of immersion (p<0.05). Conclusion: All specimens presented values for ΔE that were considered clinically inacceptable

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved