PubMed · 9582673
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M D Cooper, C M Kracher. 1998. Topical fluorides.. https://pubmed.ncbi.nlm.nih.gov/9582673/
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STATEMENT OF PROBLEM: The effect of repeated applications of fluoride solutions and 10% carbamide peroxide on the surface roughness of newer dental porcelains is not completely known. PURPOSE: The purpose of this study was to compare the surface roughness of 3 different porcelains when exposed to 2 fluoride solutions, a 10% solution of carbamide peroxide, and distilled water. MATERIAL AND METHODS: Forty discs (10-mm diameter, 2 mm thick) were made of each of the following porcelains: feldspathic porcelain (Ceramco II), low-fusing porcelain (Finesse), and an aluminous porcelain (All-Ceram). Each disc was abraded with a medium-grit diamond bur and auto-glazed. One side of each disc was abraded with a diamond bur and polished using a porcelain polishing kit to simulate a chairside adjustment and polishing. The discs (10 specimens/group) were immersed in 1.23% APF, 0.4% stannous fluoride, 10% carbamide peroxide, and distilled water for 50 seconds (control). The discs in the 10% carbamide peroxide solution were immersed for 48 hours. The surface of each disc was evaluated with surface profilometry (0.1 mm/s speed, 600-microm range). The data were analyzed by factorial analysis of variance and a Tukey multiple comparison test, (alpha=.05). RESULTS: The data showed that the acidulated phosphate fluoride etched the auto-glazed surface of all 3 porcelains. For Finesse specimens, the mean Ra values for the auto-glazed surface were significantly higher than that of the control after immersion in 1.23% APF (mean Ra 0.3 +/- 0.06 microm, P<.031). All-Ceram auto-glazed surface specimens had a significantly higher mean Ra value when immersed in the 3 solutions than the control (1.23% APF, 0.4% stannous fluoride, and 10% carbamide peroxide, 0.245 +/- 0.115 microm, 0.22 +/- 0.104 microm, 0.22 +/- 0.04 microm, respectively; P<.002). Ceramco II specimens were affected by all 3 solutions, with the auto-glazed surface having higher Ra values (1.23% APF, 0.4% stannous fluoride, and 10% carbamide peroxide, with mean Ra values of 0.35 +/- 0.1 microm, 0.26 +/- 0.08 microm, and 0.24 +/-.0.05 microm, respectively, P=.001). Immersion in the 3 solutions had no effect on the polished surfaces of all-ceramic specimens tested. CONCLUSION: Prior to the use of fluoride and 10% carbamide peroxide, dentists should ascertain the type of porcelain restoration present to prevent a roughened surface from occurring.
STATEMENT OF PROBLEM: Although acidulated phosphate fluoride (APF) agents are known to be useful for caries-preventive interventions, few studies have examined the influence of APF agents on indirect composite materials. PURPOSE: This study examined whether exposure to APF agents affects color stability when a composite is exposed to a common staining agent. MATERIALS AND METHODS: Forty light-polymerized composite disks (8 x 2.0 mm) were fabricated with midifilled (Cesead II; n = 20) and microfilled (Newmetacolor Infis; n = 20) composites. The specimens were polymerized with a light for 90 seconds on each side, ground with silicon carbide paper, finished using a polishing kit, and colorimetrically evaluated to determine baseline L*a *b* values. After storage in distilled water at 37 degrees C for 24 hours, half of the disks for each composite (n = 10) was treated with an APF solution (Fluodent A) for 32 minutes, while the remaining half of the specimens were untreated (controls). Half the treated and untreated specimens were immersed in tea or distilled water (n = 5, respectively), and after 4 weeks color changes were measured. To determine the influence of APF on each composite, the CIE L*a*b* color difference baseline values after 4 weeks were compared using 2- and 1-way analyses of variance and post-hoc Sheffe's S intervals (alpha=.05). RESULTS: The color differences of both materials when immersed in tea were significantly influenced by APF (P < .05). The mean DeltaE values of APF-treated Cesead II and Newmetacolor Infis immersed in tea were 5.4 +/- 1.2 and 4.5 +/- 1.3, respectively, while the untreated values were 3.8 +/- 0.6 and 3.0 +/- 0.1, respectively. When immersed in water, neither material was affected by APF in respect to change in color. CONCLUSION: The color of both composites tested were significantly influenced by APF treatment when immersed in tea, indicating that the in vitro color stability of the indirect composites was negatively affected by applications of APF.
The purpose of this study was to investigate the degradation in performance of four major alloys of orthodontic wires, namely nickel-titanium, beta titanium, stainless steel, and cobalt-chromium-nickel, caused by hydrogen absorption during short-term immersion in an acid fluoride solutions. The hydrogen-related degradation of orthodontic wires after immersion in 2.0% acidulated phosphate fluoride solution at 37 degrees C for 60 minutes was evaluated by a tensile test, scanning electron microscope observation, and hydrogen thermal desorption analysis. Upon immersion, the tensile strengths of the nickel-titanium and beta titanium wires decreased. Particularly, the nickel-titanium wire fractured before yielding, and the fracture mode changed from ductile to brittle. The amounts of absorbed hydrogen in the nickel-titanium and beta titanium wires were 200 and 100 mass ppm, respectively. On the other hand, the tensile strengths of the stainless steel and cobalt-chromium-nickel wires were only slightly affected by immersion. The results of this study suggest that degradation in performance of orthodontic wires of titanium alloys occurs because of hydrogen absorption even after a short-term immersion in fluoride solutions.