Chemical cleaning methods for prostheses colonized by Candida spp.: A systematic review.

STATEMENT OF PROBLEM: Different chemical agents have been used to clean and decontaminate dentures. However, consensus on their effectiveness and protocol for use is lacking. PURPOSE: The purpose of this systematic review was to evaluate chemical cleaning methods used to promote a reduction in or elimination of Candida spp. from dental prostheses. MATERIAL AND METHODS: Searches were performed in the electronic databases MEDLINE, Cochrane Library, Elsevier, Embase, SciELO, Scopus, Web of Science, Bvsalud, and Google Scholar. Manual searches were also performed. There were no restrictions on date of publication or language. Randomized clinical trials on the reduction of prosthesis surface colonization by Candida spp. by using chemical agents compared with distilled water were included. RESULTS: After the first screening, 52 studies were included, of which 5 were included for quality assessment. The studies evaluated the efficacy of alkaline peroxides, chlorhexidine, and chlorine dioxide. Among the studied solutions, alkaline peroxides demonstrated no effect on the decrease of Candida spp. on prostheses. Chlorhexidine and chlorine dioxide significantly reduced colony-forming unit (CFU) rates of these microorganisms. CONCLUSIONS: The evaluated studies presented a high risk of bias and weak evidence of the effects of chemical agents to reduce CFU counts of Candida spp. Only chlorhexidine and chlorine dioxide demonstrated some evidence of a reduction in Candida spp. colonization. Clinical trials with better methodological designs should be performed to clarify the effectiveness of these solutions in prosthesis decontamination.

Over-refractory casting technique as an alternative to one-piece multi-unit fixed partial denture frameworks.

STATEMENT OF PROBLEM: Soldering has been suggested to achieve acceptable fit of multi-unit fixed partial denture (FPD) frameworks of 3 or more elements. However, distortion of the entire framework may occur. PURPOSE: The purpose of this study was to evaluate marginal fit in 1-piece-casting FPD frameworks comparing 2 casting techniques: the conventional technique (CT) and the over-refractory technique (ORT). The techniques were evaluated on castings made from commercially pure titanium (CP Ti; Tritan), titanium-aluminum-vanadium (Ti-6Al-4V), and nickel-chromium (Ni-Cr; VeraBond II) alloys. MATERIAL AND METHODS: A metal master cast including 3 preparations was created to simulate a 5-unit FPD. The metal cast was duplicated in vinyl polysiloxane for fabrication of 60 working casts. For the CT, 0.7-mm-thick patterns were waxed on the casts using an electrical wax-dipping unit. Patterns were removed from the preparations before investing. For the ORT, the silicone impressions were poured with an investment material (Rematitan for CP Ti and Ti-6Al-4V, and Talladium for Ni-Cr). The patterns were waxed on the refractory casts, and the assembly was invested. Both CT and ORT (n = 10), CP Ti, and Ti-6Al-4V frameworks were cast using an arc-melting titanium vacuum-casting machine. The Ni-Cr frameworks were cast using an automated centrifugal-casting machine. The mean marginal discrepancies of the frameworks were measured at the mesial, distal, buccal, and lingual interfaces. Marginal gap measurements were recorded 3 times for each surface to the nearest 0.5 microm using a traveling microscope (x50). The data were analyzed with 2-way analysis of variance, followed by the Tukey HSD test (alpha=.05). RESULTS: Marginal discrepancies for the ORT specimens (82.8 +/- 1.7 microm for CP Ti; 64.4 +/- 1.3 microm for Ti-6Al-4V; and 77.2 +/- 1.5 microm for Ni-Cr) were significantly lower than those obtained for the CT specimens (106.3 +/- 2.6 microm for CP Ti; 75.7 +/- 0.8 microm for Ti-6Al-4V; 101.9 +/- 1.7 microm for Ni-Cr) (P < .05). For both techniques, marginal discrepancies were significantly different among the alloys evaluated, presenting the following order from greatest to least marginal discrepancy: CP Ti, Ni-Cr alloy, and Ti-6Al-4V (P < .05). CONCLUSION: The ORT for multi-unit FPD frameworks demonstrated significantly lower marginal discrepancies than the CT.