Effect of neodymium:yttrium-aluminum-garnet laser and fluoride on the acid demineralization of enamel.

AIM: The aim of the present study was to evaluate the protective effect of the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser and acidic phosphate fluoride (APF) on enamel erosion caused by hydrochloric acid. METHODS: Fifty human enamel specimens were distributed according to the following treatments (n = 10): untreated (control), APF (1.23%) 4 min, Nd:YAG laser (100 mJ, 1 W, 10 Hz, 141.5 J/cm2 ), APF + Nd:YAG laser, and Nd:YAG laser + APF. For 14 days the specimens were submitted to erosive challenge: 5 min in 3 mL hydrochloric acid (0.01 M, pH 2.2), rinsed with distilled water, and stored in artificial saliva for 3 h. This cycle was repeated four times per day. The calcium (Ca) loss was determined in demineralizing solution by atomic emission spectroscopy, and superficial roughness (Ra) was measured before and after the erosive challenge. RESULTS: The mean Ca loss was (mg/L, ± standard deviation): control 12.74 ± 3.33, APF 1.71 ± 0.11, laser 1.64 ± 0.08, APF + laser 1.38 ± 0.08, and laser + APF 1.48 ± 0.07. Kruskal-Wallis test showed a significant difference between the control and other groups. APF + laser showed minor loss of Ca. After the erosive challenge, the APF + laser group showed Ra alteration. CONCLUSION: A significant reduction in tooth dissolution was observed after fluoride application combined with Nd:YAG irradiation.

Corrosion behavior of pure titanium and titanium alloys in various concentrations of Acidulated Phosphate Fluoride (APF) solutions.

The corrosion behaviors of Ti, Ti-6Al-7Nb and Ti-6Al-4V alloys, and an experimentally produced Ti-0.5Pt alloy in 0.05% to 2.0% concentrations of Acidulated Phosphate Fluoride (APF) solutions (corresponding to 226 to 9,050 ppm fluoride at pH 3.5 or 3.6) were examined. While the corrosion of Ti, Ti-6Al-7Nb and Ti-6Al-4V alloys might occur easily even in a diluted 0.05% APF solution, dissolution of Ti from the Ti-0.5Pt alloy was observed only in test solutions with APF concentration exceeding 0.2%. When Ti-6Al-7Nb and Ti-6Al-4V alloys were immersed in 2.0% APF solution, their surfaces were entirely covered by compact corrosion products of Na3TiF6 due to severe corrosion. As a result, Ti dissolution was prevented and the amount of Ti dissolved decreased. However, since Ti was covered by porous, large-sized corrosion products of Na3TiF6 and that Ti-0.5Pt alloy was not covered with any corrosion product, the amount of Ti dissolved increased in the 2.0% APF solution.

Influence of acidulated phosphate fluoride solution on the color stability of indirect composites.

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.

Microleakage in amalgam restorations: influence of cavity cleanser solutions and anticariogenic agents.

This study evaluated in vitro the influence of five solutions used to treat cavity preparations on microleakage of amalgam restorations. Seventy-two standard Class V cavities were prepared in buccal and lingual surfaces of 36 recently extracted human third molars. The cervical wall was located in cementum and the occlusal wall was located in enamel. Specimens were randomly divided into six groups (n=12) according to the solution employed to treat the cavities: Group I-2.5% sodium hypochlorite; Group II-Calcium hydroxide solution; Group III-1.23% Acidulated phosphate fluoride; Group IV-2% digluconate of chlorhexidine; Group V-anionic detergent solution (1.25% sodium lauryl sulfate) and Group VI-control group. The solutions were applied for one minute, followed by washing and drying. Two coats of copal varnish were applied in each cavity. The cavities were filled with capsuled amalgam GS-80 (SDI). After finishing and polishing, the specimens were submitted for thermal cycling followed by immersion in methylene blue. Then, the specimens were sectioned and microleakage was evaluated based on a standard ranking under magnification (40x). Data were subjected to statistical analysis using non-parametric tests. Results of the study concluded that leakage was higher in cementum than enamel (p<0.01). The substances employed have no influence on microleakage except for sodium hypochlorite, which increased leakage values in enamel (p<0.05).

Fluoride varnish: a useful new tool for public health dentistry.

Since first shown to be effective by Bibby in 1942, professionally applied topical fluorides have been used successfully as a caries-preventive intervention. In the United States, the acidulated phosphate fluoride (APF) gels have been the most widely used agent for over two decades. While effective, APF has several practical disadvantages, including unpleasant taste and the risk of fluoride overingestion. The use of APF on infants and very young children is not practical or safe. Recently, fluoride varnish has become available in the United States. It has been used widely in Europe and Scandinavia for 25 years. Its effectiveness and safety are documented in over 50 clinical trials. Fluoride varnish is easy to apply, is well accepted by children, and eliminates the risk of overingestion of fluoride. Fluoride varnish is approved by the FDA as a "device" and must be used "off label" for the prevention of caries. Because of the large body of published data documenting its effectiveness and safety, there is no legal risk in using fluoride varnish off label. In fact, the American Dental Association has granted its seal of approval to Duraphat, one of the varnish products. Varnish offers considerable advantages in the dental public health setting. Of particular note, it is practical and safe to apply to the teeth of infants and very young children.