The role of welding techniques in the biomechanical behavior of implant-supported prostheses.

This in vitro study investigated the role of welding techniques of implant-supported prostheses in the 2D and 3D marginal misfits of prosthetic frameworks, strain induced on the mini abutment, and detorque of prosthetic screws. The correlations between the analyzed variables were also investigated. Frameworks were cast in commercially pure titanium (cp-Ti). A marginal misfit of 200µm was simulated in the working models (control group) (n=20). The 2D marginal misfit was analyzed according to the single-screw test protocol using a precision optical microscope. The 3D marginal misfit was performed by X-ray microtomography. Strain gauge analysis was performed to investigate the strain induced on the mini abutment. A digital torque meter was used for analysis of the detorque and the mean value was calculated for each framework. Afterwards, the frameworks were divided into two experimental groups (n=10): Laser (L) and TIG (T). The welding techniques were performed according to the following parameters: L (390V/9ms); T (36A/60ms). The L and T groups were reevaluated according to the marginal misfit, strain, and detorque. The results were submitted to one-way ANOVA followed by Tukey's HSD test and Person correlation analysis (α=0.05). Welding techniques statistically reduced the 2D and 3D marginal misfits of prosthetic frameworks (p<0.001), the strain induced on the mini abutment replicas (p=0.006), and improved the screw torque maintenance (p<0.001). Similar behavior was noted between L and T groups for all dependent variables (p>0.05). Positive correlations were observed between 2D and 3D marginal misfit reading methods (r=0.943, p<0.0001) and between misfit and strain (2D r=0.844, p<0.0001 and 3D r=0.864, p<0.0001). Negative correlation was observed between misfit and detorque (2D r=-0.823, p=0.003 and 3D r=-0.811, p=0.005). In conclusion, the welding techniques improved the biomechanical behavior of the implant-supported system. TIG can be an acceptable and affordable technique to reduce the misfit of 3-unit Ti frameworks.

Effect of chemical cleaning agents on the flexural strength of acrylic and hard denture line resins.

This study sought to evaluate the disinfectants, Efferdent (EF) and 0.5% sodium hypochlorite (SH), and their effects on the flexural strength and modulus of elasticity of the hard denture liners, Kooliner (K) and New Truliner (NT), and a thermoacrylic resin, QC-20. Ninety specimens were made (50 mm x 10 mm x 3 mm) and divided into 9 groups (n = 10). The 3 control groups were Group 1: QC-20 without disinfection cycles, Group 2: K, and Group 3: NT. The 6 experimental groups were Group 4: QC-20 in EF, Group 5: K in EF, Group 6: NT in EF, Group 7: QC-20 in SH, Group 8: K in SH, and Group 9: NT in SH. Specimens were subjected to 360 cycles of disinfection involving 35-minute cycles of immersion in cleaning solutions. The materials' flexural strength and modulus of elasticity were determined using a universal testing machine at a 5 mm/minute speed of compression. The data were subjected to ANOVA, Tukey, Kruskal-Wallis, and Dunn tests (α = 0.05). Regardless of the disinfection method used, the NT hard denture liner showed the lowest flexural strength values (P < 0.05) and modulus of elasticity (P < 0.0001) compared to K and QC-20. However, flexural strength values increased after applying SH and EF (P < 0.05). QC-20 showed a higher modulus of elasticity (P < 0.033), which increased after EF was applied (P = 0.005). It can be concluded that the disinfection methods changed the mechanical properties of the tested materials.

Educação em saúde em comunidades quilombolas / Health education in quilombola communities

Objetivo: Avaliar o conhecimento sobre saúde bucal dos pais e filhos presentes nas comunidades quilombolas localizadas na região do Vale do Ribeira, São Paulo. Métodos: Foram desenvolvidas nas comunidades (André Lopes, Ivaporunduva, Pedro Cubas e Sapatu) atividades educativas e preventivas sobre saúde bucal com as crianças, por meio de palestras, orientações de técnica de escovação, escovação em massa supervisionada, revelação de biofilme dental e aplicação tópica de flúor. Os pais das crianças também participaram das atividades em que foram avaliados sobre a saúde bucal de seus filhos, por meio da aplicação de um questionário padronizado. Além disso, também foi realizada a análise da água de abastecimento das comunidades.Resultados: As crianças apresentaram-se entusiasmadas, receptivas e participativas durante o desenvolvimento das atividades educativas e preventivas. Sobre a aplicação dos questionários, 56,0% dos pais declaram que é ruim a saúde bucal dos seus filhos e 47,2% costumam acompanhar a higienização bucal até os seis anos de idade, aproximadamente, sendo que esse acompanhamento não é frequente.Conclusão: Concluiu-se que pais e filhos quilombolas possuem pouco conhecimento sobre saúde bucal, assim observa-se à necessidade de maior atenção à saúde bucal nessas comunidades, por meio de frequentes ações de educação e promoção de saúde bucal.

Objective: To appraise the oral health knowledge of parents and children from the quilombola communities located in the Ribeira Valley, Sao Paulo.Methods: Preventive and educational activities in oral health were developed with children in the communities (Andre Lopes, Ivaporunduva, Pedro Cubas and Sapatu) including lectures, guidance on tooth brushing techniques, supervised mass brushing, detection of tooth biofilm and topical application of fluoride. Parents also participated in the activities. They were evaluated on the oral health of their children by means of a standard questionnaire. The water supply of the communities was also analyzed. Results: The children participated enthusiastically and responsively in the preventive and educational activities. As to the questionnaires, 56% of parents stated that their children?s oral health was poor and 47.2% of them usually follow up on their children?s oral hygiene until they are approximately six years old, but this follow-up is not frequent. Conclusion: We conclude that quilombola parents and children have very little knowledge about oral health. Therefore increased attention to oral health is required in these communities by means of frequent oral health education and promotion.