The effect of Galilean magnification loupes on the visual acuity and working distance of dental students.

OBJECTIVE: This study aimed to evaluate the visual acuity and working distance of dental students using Galilean loupes at different magnification levels. METHODS: The participants included 50 undergraduate dentistry students selected from each class in the second to fifth years (N = 200) of São Paulo State University, School of Dentistry, Araraquara. The response variables were (i) the working distance between the operator's eyes and the mouth of the dental phantom head, and (ii) visual acuity. The independent variables were the five levels of the Galilean magnification system (naked eye, Galilean loupe simulator without magnification, and Galilean loupes with 2.5×, 3.0×, or 3.5× magnification) and academic year. Visual acuity was measured using a miniature Snellen eye chart inserted into the Class I cavities of the maxillary molars. After verifying the assumptions of normality and sphericity, a mixed repeated measures analysis was performed (α = 0.05). RESULTS: Statistical significance was found between the "magnification system" and "academic year" for visual acuity (p < 0.001). For the second-, fourth-, and fifth-year participants, there were no significant differences in visual acuity between the naked eye and different magnifications of the Galilean loupes, which were superior to and significantly different from that of the loupe simulator. For the working distance, statistical significance was observed in the interaction between "magnification system" and "academic year" (p = 0.008). For the third-, fourth-, and fifth-year participants, there was no significant difference in the working distance between the naked eye and different magnifications of the Galilean loupes, which were superior to and significantly different from that of the simulator. CONCLUSION: It was concluded that the different magnification levels of the Galilean loupes did not influence the visual acuity or distance between the eyes of the operator and the mouth of the dental phantom head in the evaluated students.

Influence of simulated gastric juice on surface characteristics of CAD-CAM monolithic materials.

STATEMENT OF PROBLEM: How the surfaces of monolithic esthetic restorations behave in the presence of acidic substances is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the effect of simulated gastric juice on roughness, morphology, microhardness, substance loss, and color change of computer-aided design and computer-aided manufacturing (CAD-CAM) monolithic materials. MATERIAL AND METHODS: Disks from Lava Ultimate, VITA ENAMIC, IPS e.max CAD, and VITA SUPRINITY were analyzed for roughness, morphology, and microhardness by using a confocal microscope, scanning electron microscope (SEM), and Vickers hardness tester. Substance loss was determined by weighing the specimens on an analytical balance, and color change (ΔE) was assessed by using a spectrophotometer based on the CIELab parameters. All analyses were carried out before and after acid exposure. RESULTS: Acid exposure significantly decreased the roughness, having a very high effect size on this property. The material was highly decisive in determining the microhardness, presenting the following order: VITA SUPRINITY>IPS e.max CAD>VITA ENAMIC>Lava Ultimate. The mass was not significantly affected by the acidic challenge. No significant difference in ΔE was found between Lava Ultimate and VITA ENAMIC and between IPS e.max CAD and VITA SUPRINITY. Lava Ultimate showed a higher ΔE than IPS e.max CAD and VITA SUPRINITY, whereas VITA ENAMIC exhibited higher ΔE only when compared with VITA SUPRINITY. All materials presented ΔE<1. CONCLUSIONS: The simulated gastric juice significantly influenced the roughness of all the evaluated materials and promoted a color change classified as clinically undetectable in all materials.

Near-infrared photodynamic inactivation of S. pneumoniae and its interaction with RAW 264.7 macrophages.

Pneumonia is the main cause of children mortality worldwide, and its major treatment obstacle stems from the microorganisms increasing development of resistance to several antibiotics. Photodynamic therapy has been presenting, for the last decades, promising results for some subtypes of cancer and infections. In this work we aimed to develop a safe and efficient in vitro protocol for photodynamic inactivation of Streptococcus pneumoniae, one of the most commonly found bacteria in pneumonia cases, using two near-infrared light sources and indocyanine green, a FDA approved dye. Photodynamic inactivation experiments with bacteria alone allowed to determine the best parameters for microbial inactivation. Cytotoxicity assays with RAW 264.7 macrophages evaluated the safety of the PDI. To determine if the photodynamic inactivation had a positive or negative effect on the natural killing action of macrophages, we selected and tested fewer indocyanine green concentrations and 10 J/cm2 on macrophage-S. pneumoniae co-cultures. We concluded that ICG has potential as a photosensitizer for near-infrared photodynamic inactivation of S. pneumoniae, producing minimum negative impact on RAW 264.7 macrophages and having a positive interaction with the immune cell's microbicidal action.

Potential of curcumin-mediated photodynamic inactivation to reduce oral colonization.

OBJECTIVE: The present study assessed the susceptibility of salivary pathogens to photodynamic inactivation (PDI), mediated by a water-soluble mixture of curcuminoids (CRM) and LED light. METHODS: A 10mL sample of unstimulated saliva was collected from volunteers. The inoculum was prepared using 9mL of saline and 1mL of saliva. Inoculum suspensions were divided into 14 groups and treated according to the description below. Groups that received the PDI treatment (light for 1min or 5min and 1.5g/L or 3.0g/L of CRM concentration) were called C1.5L1.8, C1.5L9.0, C3.0L1.8, C3.0L9.0. To evaluate the CRM decontamination alone, the C1.5/1,C1.5/5,C3.0/1 and C3.0/5 groups were assessed. Likewise, light alone was evaluated through the L1.8 and L9.0 groups. Chlorhexidine at 0.12% (CLX) for 1 or 5min was used for the positive control groups (CLX1 and CLX5, respectively); saline was used for 1 or 5min (CTR1, CTR5, respectively) for the negative control groups. After the tests, serial dilutions were performed, and the resulting samples were plated on blood agar in microaerophilic conditions. The number of colony forming units (CFU/mL) was determined and log10-transformed. Data were analyzed using a One-way Analysis of Variance with Welch correction, followed by the Games Howell's test (α=0.05). Log reduction (LR) measure for antimicrobial efficacy was also calculated using data from the CTR5 as untreated samples. RESULTS: The CHX5 showed the best antimicrobial result, followed by the CLX1. The antimicrobial effect of CRM was more pronounced when associated with light (PDI), but significantly lower than the CLX5 effect. The C3.0L9.0 protocol showed similar results to the CLX1. CONCLUSION: The results show that PDI with CRM at the studied concentrations is as effective for oral decontamination in clinical dental care conditions as the CLX at 0.12% for 1min.

Prevalence of Candida spp. associated with bacteria species on complete dentures.

OBJECTIVE: This study evaluated the prevalence of Candida spp., Streptococcus mutans and Staphylococcus aureus isolated from complete upper dentures. BACKGROUND: Factors that may increase the number of microorganisms in the oral cavity include denture-wearing and deficient denture hygiene. MATERIALS AND METHODS: Ninety denture wearers participated in this study. Collection of biological material from each denture was performed on all denture surfaces. Conventional biochemical methods were used to identify the microorganisms. Descriptive statistical analysis was performed on percentage data. RESULTS: Candida spp. were the most frequent microorganisms found on dentures (65.5%), while Strep. mutans and Staph. aureus were present in 53.3 and 34.4%, respectively. CONCLUSION: Candida species were the most frequent microorganisms on dentures, followed by Strep. mutans and Staph. aureus.

Susceptibility of clinical isolates of Candida to photodynamic effects of curcumin.

BACKGROUND AND OBJECTIVE: The resistance of Candida species to antifungals represents a major challenge for therapeutic and prophylactic strategies. This study evaluated photodynamic therapy (PDT) mediated by Curcumin (CUR) against clinical isolates of C. albicans, C. tropicalis, and C. glabrata, both in planktonic and biofilm forms. STUDY DESIGN/MATERIALS AND METHODS: Suspensions of Candida were treated with three CUR concentrations and exposed to four LED fluences. The protocol that showed the best outcomes for inactivation of the planktonic phase was selected to be evaluated against Candida biofilms. In addition, two higher CUR concentrations were tested. The metabolic activity of biofilms was evaluated by means of XTT reduction assay and the biofilm biomass was evaluated using crystal violet (CV) staining assay. Data were analyzed in a mixed model nested ANOVA, Wilcoxon's nonparametric tests, and the Kruskal-Wallis test (α = 5%). RESULTS: The use of CUR in association with light was able to promote a significant antifungal effect against the planktonic form of the yeasts. When using 40 µM of CUR, the metabolic activity of C. albicans, C. glabrata, and C. tropicalis biofilms was reduced by 85%, 85%, and 73%, respectively, at 18 J/cm(2) . CUR-mediated PDT also decreased the biofilm biomass of all species evaluated. In addition, CV staining showed that C. albicans isolates were strong biofilm-forming strains, when compared with C. glabrata and C. tropicalis isolates. CONCLUSION: The results from the present investigation showed that low CUR concentrations can be highly effective for inactivating Candida isolates when associated with light excitation.

Investigation of the photodynamic effects of curcumin against Candida albicans.

This study describes the association of curcumin with light emitting diode (LED) for the inactivation of Candida albicans. Suspensions of Candida were treated with nine curcumin concentrations and exposed to LED at different fluences. The protocol that showed the best outcomes for Candida inactivation was selected to evaluate the effect of the preirradiation time (PIT) on photodynamic therapy (PDT) effectiveness, the uptake of curcumin by C. albicans cells and the possible involvement of singlet oxygen in the photodynamic action. Curcumin-mediated PDT was also assessed against biofilms. In addition to the microbiological experiments, similar protocols were tested on a macrophage cell line and the effect was evaluated by Methyltetrazolium assay (MTT) and SEM analysis. The optical properties of curcumin were investigated as a function of illumination fluence. When compared with the control group, a statistically significant reduction in C. albicans viability was observed after PDT (P < 0.05), for both planktonic and biofilm cultures. Photodynamic effect was greatly increased with the presence of curcumin in the surrounding media and the PIT of 20 min improved PDT effectiveness against biofilms. Although PDT was phototoxic to macrophages, the therapy was more effective in inactivating the yeast cell than the defense cell. The spectral changes showed a high photobleaching rate of curcumin.