In vitro effect of topical fluoride on dental porcelain.
ABSTRACT Fifty-seven porcelain samples were randomly subjected to a variety of topical fluorides for time intervals of 4 to 64 minutes. Half of each porcelain surface was masked to prevent contact with the fluoride. Measurements of roughness were made for the fluoride-treated and the untreated porcelain surfaces to evaluate the effect of the different fluoride preparations over time. The resulting surfaces were also examined using an SEM. Conclusions from this study include the following. Statistically significant differences in roughness were found among surfaces exposed to 1.23% acidulated phosphate fluoride gel, 8% stannous fluoride, and the control surfaces. There were no significant differences in roughness between the test and control surfaces with 0.05%, 0.2%, and 2% sodium fluoride solutions or 0.4% stannous fluoride gel. The dentist should be aware of the potentially deleterious effects of prescribing or administering a topical fluoride for patients with porcelain/metal restorations.
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ABSTRACT: 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. This study examined whether exposure to APF agents affects color stability when a composite is exposed to a common staining agent. 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). 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. 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.Journal of Prosthetic Dentistry 11/2004; 92(4):343-7. · 1.72 Impact Factor
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ABSTRACT: This study evaluated the durability of bond strength between resin cement and a feldspathic ceramic submitted to different etching regimens with and without silane coupling agent application. Thirty-two blocks (6.4 mm x 6.4 mm x 4.8 mm) were fabricated using a microparticulate feldspathic ceramic (Vita VM7), ultrasonically cleaned with water for 5 min and randomly divided into four groups, according to the type of etching agent and silanization method: method 1, etching with 10% hydrofluoric (HF) acid gel for 1 min + silanization; method 2, HF only; method 3, etching with 1.23% acidulated phosphate fluoride (APF) for 5 min + silanization; method 4, APF only. Conditioned blocks were positioned in their individual silicone molds and resin cement (Panavia F) was applied on the treated surfaces. Specimens were stored in distilled water (37 degrees C) for 24h prior to sectioning. After sectioning the ceramic-cement blocks in x- and y-axis with a bonded area of approximately 0.6mm(2), the microsticks of each block were randomly divided into two storage conditions: Dry, immediate testing; TC, thermal cycling (12,000 times)+water storage for 150 d, yielding to eight experimental groups. Microtensile bond strength tests were performed in universal testing machine (cross-head speed: 1mm/min) and failure types were noted. Data obtained (MPa) were analyzed with three-way ANOVA and Tukey's test (alpha=0.05). Significant influence of the use of silane (p<0.0001), storage conditions (p=0.0013) and surface treatment were observed (p=0.0014). The highest bond strengths were achieved in both dry and thermocycled conditions when the ceramics were etched with HF acid gel and silanized (17.4 +/- 5.8 and 17.4 +/- 4.8 MPa, respectively). Silanization after HF acid gel and APF treatment increased the results dramatically (14.5+/-4.2-17.4+/-4.8 MPa) compared to non-silanized groups (2.6 +/- 0.8-8.9 +/- 3.1 MPa) where the failure type was exclusively (100%) adhesive between the cement and the ceramic. Silanization of the feldspathic ceramic surface after APF or HF acid etching increased the microtensile bond strength results significantly, with the latter providing higher results. Long-term thermocycling and water storage did not decrease the results in silanized groups.Dental Materials 11/2007; 23(11):1323-31. · 3.77 Impact Factor
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ABSTRACT: Long-term fluoride application on the teeth of patients receiving radiation therapy for head and neck tumors results in excessive staining and roughening of ceramic restorations. The purpose of this in vitro study was to compare the staining effects of 2 fluoride treatments on ceramic disks by simulating 1 year of clinical exposure at 10 minutes per day. In addition, 2 different surface preparations were tested. Eighty ceramic disks (IPS Empress), 20 x 2 mm, were fabricated. Half of the disks were glazed, and the remaining disks were polished. All disks were brushed for 3 minutes with a soft-bristle power toothbrush and mild dentifrice (baseline) and were immersed in 1 of the 2 fluoride products (0.4% SnF(2), Gel-Kam Gel, or 1.1% NaF, Prevident 5000) for 10 days (n=20). Means and standard deviations of color change (Delta E), surface roughness (Ra, um), and surface gloss (GU) of the ceramic material were measured with a reflection spectrophotometer, a profilometer, and a gloss meter, respectively, at baseline and after fluoride treatment. Two- and 3-way ANOVA (alpha=.05), with surface preparation (polished vs. glazed) and fluoride treatment (0.4% SnF(2) or 1.1% NaF) as independent variables and condition (baseline vs. after fluoride treatment) as a repeated measure, was used to analyze the data. Fisher's PLSD intervals (alpha=.05) were calculated for comparisons among the means. The polished specimens had significantly higher Delta E values, significantly higher surface gloss values, and significantly lower surface roughness values than the glazed specimens before fluoride treatment (P<.001). After both fluoride treatments, ceramic disks exhibited significantly higher surface roughness values when polished and significantly lower surface gloss values when glazed or polished (P<.001). The glazed specimens presented significantly higher surface roughness (P<.001) and lower surface gloss values (P<.001) when treated with 0.4% SnF(2) as compared to NaF. For the polished specimens, there was no significant difference in surface roughness and surface gloss values between the 2 fluoride treatments. Use of 0.4% SnF(2) and 1.1% NaF gels, in vitro, caused significant color change in the polished IPS Empress ceramic disks. Polishing of the ceramic surface before immersion in either fluoride agent caused the ceramic tested to be more resistant to etching by the 2 solutions tested. The NaF caused less deterioration of the porcelain surface and was less stain inducing than SnF(2).The Journal of prosthetic dentistry 03/2010; 103(3):163-9. · 1.22 Impact Factor