Effects of chemical composition on the corrosion of dental alloys

The aim of this study was to determine the effect of the oral environment on the corrosion of dental alloys with different compositions, using electrochemical methods. The corrosion rates were obtained from the current-potential curves and electrochemical impedance spectroscopy (EIS). The effect of artificial saliva on the corrosion of dental alloys was dependent on alloy composition. Dissolution of the ions occurred in all tested dental alloys and the results were strongly dependent on the general alloy composition. Regarding the alloys containing nickel, the Ni-Cr and Ni-Cr-Ti alloys released 0.62 mg/L of Ni on average, while the Co-Cr dental alloy released ions between 0.01 and 0.03 mg/L of Co and Cr, respectively.The open-circuit potential stabilized at a higher level with lower deviation (standard deviation: Ni-Cr-6Ti = 32 mV/SCE and Co-Cr = 54 mV/SCE). The potenciodynamic curves of the dental alloys showed that the Ni-based dental alloy with >70 wt% of Ni had a similar curve and the Co-Cr dental alloy showed a low current density and hence a high resistance to corrosion compared with the Ni-based dental alloys. Some changes in microstructure were observed and this fact influenced the corrosion behavior for the alloys. The lower corrosion resistance also led to greater release of nickel ions to the medium. The quantity of Co ions released from the Co-Cr-Mo alloy was relatively small in the solutions. In addition, the quantity of Cr ions released into the artificial saliva from the Co-Cr alloy was lower than Cr release from the Ni-based dental alloys.     

In vitro susceptibility of oral Candida albicans strains to different pH levels and calcium hydroxide saturated aqueous solution

Candida albicans is present in the oral cavity and in the whole digestive tract of humans and other animals, being frequently related to endodontic treatment failure. The present study determined the incidence of C. albicans in the oral cavity and the susceptibility of isolates to different pH values and saturated calcium hydroxide aqueous solution at pH 12.5. Sixty-five patients attending the Endodontic Clinic at the Sagrado Cora??o University participated in the study. The collected samples were cultivated in selective media for C. albicans and the isolates were tested in terms of resistance to both alkaline pH and saturated aqueous solution of calcium hydroxide. In relation to time variables, yeast viability was assessed by the Sabouraud's agar culture and fluorescein diacetate and ethidium bromide fluorescent staining method. Results from the different pHs and experimental times, including those from different techniques measuring fungal viability, were compared using the chi-square and Fisher's exact tests (α=0.05). The yeasts became completely inviable after 48 h of contact with the calcium hydroxide solution. On the other hand, when exposed to the alkaline culture broth, the yeasts were found to be viable at pHs 9.5 and 10.5 for up to 7 days. In conclusion, C. albicans can only be completely inhibited by direct contact with saturated calcium hydroxide aqueous solution after 48 h of exposure.     

Primary piggyback implantation using the Tecnis ZM900 multifocal intraocular lens: case series

PURPOSE: To assess the postoperative outcomes of primary piggyback implantation using the Tecnis ZM900 multifocal intraocular lens (IOL) (Advanced Medical Optics). SETTING: Hospital Oftalmológico de Brasília, Brasília, Brazil. METHODS: Patients who had phacoemulsification with primary piggyback IOL implantation were analyzed prospectively. In all cases, a Tecnis ZM900 multifocal IOL was implanted in the capsular bag and a second silicone IOL was implanted in the ciliary sulcus. Information collected included near and distance uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), and the spherical equivalent (SE) before and after the surgery. RESULTS: Twenty eyes of 12 patients were included in the study. They were followed for 6 months. The mean preoperative distance UCVA was 20/400. At the last follow-up (6 months), the mean distance UCVA was 20/29, significantly better than before referral (P<.001). The mean preoperative SE was +6.35 diopters (D) +/- 2.25 (SD). Six months after surgery, the mean SE was -0.25 +/- 0.40 D (range -1.00 to +0.50 D), significantly better than before referral (P<.001). No patient lost lines of BCVA after surgery. At the last follow-up, 90% of the eyes achieved a near UCVA of J1 and 83.3% of patients were spectacle independent for near and distance vision. A second refractive procedure was performed in 2 eyes. CONCLUSIONS: Primary piggyback implantation using the Tecnis ZM900 multifocal IOL was a simple, safe, and accurate option for patients with high hyperopia who wanted to reduce their dependency on spectacles.     

The role of exercise testing in predicting successful ambulation with a lower extremity prosthesis: a systematic literature review and clinical practice guideline

Background

Growing discontent with the k-level system for functional classification of patients with limb loss and movement of healthcare toward evidence-based practice has resulted in the need for alternative forms of functional classification and development of clinical practice guidelines to improve access to quality prosthetic interventions. The purpose of this project was to develop and present a clinical practice recommendation for exercise testing in prosthetic patient care based on the results and synthesis of a systematic literature review.

Methods

Database searches of PubMed, Google Scholar, Web of Science, and Cochrane were conducted and articles reviewed. Of the potential 1386 articles 10 met the criteria for inclusion. These articles were assessed using the critical appraisal tool of the United Kingdom National Service Framework for Long-Term Conditions. Of the 10 included articles eight were of high, one of medium, and one of low, quality. Data from these articles were synthesized into 6 empirical evidence statements, all qualifying for research grade A. These statements were used to develop the proposed clinical practice guideline.

Results

While the results of this systematic review were not able to support the direct connection between cardiorespiratory performance and K-levels, the literature did support the ability of exercise testing results to predict successful prosthetic ambulation in some demographics. Both continuous maximum-intensity single lower extremity ergometer propelled by a sound limb and intermittent submaximal upper extremity ergometer protocols were found to be viable evaluation tools of cardiorespiratory fitness and function in the target population.

Conclusion

The ability to sustain an exercise intensity of ≥50% of a predicted VO_2max value in single leg cycle ergometry testing and achievement of a sustained workload of 30 W in upper extremity ergometry testing were found to be the strongest correlates to successful ambulation with a prosthesis. VO₂ values were found to increase in amputee subjects following a 6-week exercise program. These synthesized results of the systematic literature review regarding exercise testing in patients with loss of a lower extremity were used to develop and a present a clinical treatment pathway.

     

The late effect of Kinesio Taping® on handgrip strength

Kinesio Taping^® elastic tape is increasingly used in physiotherapy treatment. However, there is a lack of scientific research regarding the late effects of its use. This study quantified the late effects of applying the Kinesio Taping^® elastic tape by measuring changes in handgrip muscle strength after 24, 48 and 72 h of application. The Kinesio Taping^® elastic tape was applied on the dominant and non-dominant limbs of 36 volunteers randomly assigned to three groups: muscle facilitation, muscle inhibition and control group. The statistical test showed there was a statistically significant difference among all groups of dominant limb and non-dominant limb. However, the analysis on intragroup relationship to periods of application (Initial, 24, 48 and 72 h) and the interaction among repeated measures showed there was no statistically significant difference. This result may contribute to the investigation of the late effects of the Kinesio Taping^® elastic tape on the physical rehabilitation.