Synthesis and characterization of TPP/chitosan nanoparticles: Colloidal mechanism of reaction and antifungal effect on C. albicans biofilm formation.

In the present study chitosan (Chit) nanoparticles were synthetized by the ionic gelation process, using tripolyphosphate (TPP) as crosslinking agent. The TPP/Chit nanoparticle formation was evaluated by titrations, measuring electrical conductivity (k), zeta potential (ZP), hydrodynamic diameter (Dh), viscosity (η) and heat by isothermal calorimetry (ITC). The antifungal effects were evaluated by C. albicans time-kill assays, inhibition of C. albicans initial adhesion and biofilm formation in comparison with nystatin and chitosan. Conductometric titration exhibited a typical precipitation profile, with an inflection at molar ratio of [TPP]/[Chitmon] ≈ 0.3, suggesting a 1:3.3 stoichiometry. The highest Dh, ZP and η values were shown at the beginning of titrations, due to the intramolecular repulsion between Chit-Chit. With addition of TPP, the values showed gradual reduction, with an intermediary transition at [TPP]/[Chitmon] ≈ 0.16, which was attributed to the partial breakdown of interchain crosslinking and formation of discrete charged aggregates. After this point, reaction should occur by neutralization of these assemblies, causing new reduction in values of Dh, ZP and η until [TPP]/[Chitmon] ≈ 0.3, when they reached their lowest values. ITC experiment also showed the occurrence of two bindings (K1 = 3.6 × 103 and K2 = 7.7 × 104), which were entropy driven. Biological results showed lower C. albicans viability for TPP/Chit over 24 h compared with chitosan and nystatin at MIC and 2 MIC. Moreover, TPP/Chit showed 25-50% inhibition of C. albicans adhesion and biofilm formation. The results showed that TPP/Chit nanoparticles reduced the initial adhesion and biofilm formation of C. albicans and demonstrated potential for use in a formulation for the treatment of oral candidiasis.

Antifungal activity, mode of action and anti-biofilm effects of Laurus nobilis Linnaeus essential oil against Candida spp.

OBJECTIVE: The present study demonstrated the antifungal potential of the chemically characterized essential oil (EO) of Laurus nobilis L. (bay laurel) against Candida spp. biofilm adhesion and formation, and further established its mode of action on C. albicans. METHODS: L. nobilis EO was obtained and tested for its minimum inhibitory and fungicidal concentrations (MIC/MFC) against Candida spp., as well as for interaction with cell wall biosynthesis and membrane ionic permeability. Then we evaluated its effects on the adhesion, formation, and reduction of 48hC. albicans biofilms. The EO phytochemical profile was determined by gas chromatography coupled to mass spectrometry (GC/MS). RESULTS: The MIC and MFC values of the EO ranged from (250 to 500) µg/mL. The MIC values increased in the presence of sorbitol (osmotic protector) and ergosterol, which indicates that the EO may affect cell wall biosynthesis and membrane ionic permeability, respectively. At 2 MIC the EO disrupted initial adhesion of C. albicans biofilms (p<0.05) and affected biofilm formation with no difference compared to nystatin (p>0.05). When applied for 1min, every 8h, for 24h and 48h, the EO reduced the amount of C. albicans mature biofilm with no difference in relation to nystatin (p>0.05). The phytochemical analysis identified isoeugenol as the major compound (53.49%) in the sample. CONCLUSIONS: L. nobilis EO has antifungal activity probably due to monoterpenes and sesquiterpenes in its composition. This EO may affect cell wall biosynthesis and membrane permeability, and showed deleterious effects against C. albicans biofilms.

In vitro Effect of Erosive Challenge on Surface Microhardness of Orthodontic Composites

Objective: To evaluate in vitro the effect of erosive challenge and continuous immersion in cola drink on surface microhardness of orthodontic composites. Material and Methods: Forty samples of three composites (Transbond XT, Quick Cure and Ortho Cem) were prepared (4 x 2 mm) and distributed into 4 groups (n=10): erosive challenge, artificial saliva immersion (control 1), continuous cola immersion and artificial saliva immersion (control 2). Erosive challenge was performed 4 times per day (5 min) in cola drink for 2 h in artificial saliva for 7 days. Samples of continuous cola immersion group were soaked in cola drink for 5 weeks and the beverage was renewed every two days. Control samples were immersed in artificial saliva for 7 days (control 1) and 5 weeks (control 2). Vickers microhardness (VHN) measurements were performed before and after erosive challenge and continuous immersion. Data were evaluated by paired Student's T-test, ANOVA one-way and Tukey tests (α = 0.05). Results: After 7 days of erosive challenge, there was no statistical difference between VHN values before and after erosive challenge and artificial saliva immersion. However, after 5 weeks of cola drink and artificial saliva immersion, significant reduction in VHN values was observed for all composites when compared to baseline values, and specimens immersed in cola drink showed lower VHN compared to those immersed in saliva, regardless of composite composition. Conclusion: After 7 days of erosive challenge, there was no alteration in superficial VHN of orthodontic composites. However, after 5 weeks of immersion in cola drink, significant reduction of VHN values was observed for all composites.

Tratamientos menos invasivos: utilización de los sistemas de aire abrasivo y puntas cvd

Los sistemas de preparación cavitaria a base de aire abrasivo y puntas CVD fueron desarrollados para confeccionar cavidades con características diferentes a las obtenidas por los sistemas convencionales. Trabajos anteriores demuestran la efectividad de corte de ambos sistemas favoreciendo de esa manera la preparación de cavidades de forma más conservadora lo que permite la práctica de una “Odontología mínimamente invasiva”. El presente trabajo tiene por objetivo presentar por medio del relato de un caso clínico la forma de utilización, características de las preparaciones así como las ventajas y desventajas que ambos sistemas presentan. Los dos sistemas fueron utilizados para la remoción de lesiones de caries inicial en las superficies oclusales de los primeros molares permanentes de un paciente de 9 años de edad. En los molares 16 y 46 fue utilizado el Sistema de Aire Abrasivo y en los molares 26 y 36 el sistema de puntas CVDentusâ. De las observaciones realizadas podemos concluir que estos sistemas fueron confortables para el paciente debido a las características de funcionamiento y eficiencia de los aparatos, contribuyendo de esta forma para la colaboración y buen comportamiento del paciente, así como, facilitar la acción del operador.

The cavity systems preparation with abrasive air and burs CVD were developed to make cavities with characteristics different from the obtained by the conventional systems. Previous works demonstrate to the effectiveness of cut of both systems favoring of that way the preparation of cavities of more preservative form what the practice of a "minimally invasive Dentistry" allows. The present work must by objective present by means of the story of a clinical case the use form, characteristics of the preparations as well as the advantages and disadvantages that both systems display. Both systems were used for the removal of damages of initial decay in permanent the oclusal surfaces of first molars of a patient of 9 years of age. In molars 16 and 46 the System of Abrasive Air was used and in molars 26 and 36 the system of CVDentus. of the made observations we can conclude that these systems were comfortable for the patient due to the characteristics of operation and efficiency of the appliances, contributing of this form for the collaboration and good behavior of the patient, as well as, to facilitate the action of the operator.

A preparação dos sistemas da cavidade com CVD abrasivo do ar e das queimaduras foi desenvolvida a faça cavidades com as características diferentes do obtido pelos sistemas convencionais. Precedente os trabalhos demonstram à eficácia do corte de favorecer de ambos os sistemas daquele maneira a preparação das cavidades do formulário mais preservativo que a prática "um Odontologia minimamente invasiva" reserva. o trabalho atual deve pelo objetivo atual por meio da história de um caso clínico o formulário do uso, características das preparações as vantagens e desvantagens que ambos os sistemas indicam. Ambos os sistemas foram usados para a remoção dos ferimentos da deterioração inicial no permanente superfícies dos oclusales de primeiros molares de um paciente de 9 anos de idade. Nos molares 16 e 46 o sistema do ar abrasivo foram usados e nos molares 26 e 36 o sistema de CVDentus. Das observações feitas nós podemos concluir que estes sistemas eram confortáveis para paciente devido às características da operação e da eficiência dos instrumentos, contribuir deste formulário para a colaboração e comportamento bom do paciente, para facilitar a ação do operador.