Fluoride levels in dentin after iontophoresis of 2% NaF

Effect of tooth-brushing with a microcurrent on dentinal tubule occlusion

The purpose of this study was to investigate whether tooth-brushing with a microcurrent was effective in inducing dentinal tubule occlusion. The specific aims of the study were (1) to evaluate the effectiveness of tooth-brushing with a microcurrent on dentinal tubule occlusion by using scanning electron microscopy (SEM); and (2) to compare the dentinal fluid flow rate after tooth-brushing with a microcurrent by using a sub-nanoliter-scaled fluid flow measuring device (NFMD). All experimental groups showed partially occluded dentinal tubules and crystal-like structures at a specific microcurrent intensity indicated that tooth-brushing with a microcurrent could efficiently occlude dentinal tubules. The decrease in dentinal fluid flow rate in the tooth-brushing with microcurrents group indicated that dentinal tubules were occluded and the flow of dentinal fluid had decreased.

Effect of fluoride iontophoresis on the microtensile bond strength between dentin and two adhesive systems

AIM

To evaluate the effect of fluoride iontophoresis on the microtensile bond strength (MTBS) between coronal dentin and two resin-based adhesive systems, and to measure quantitatively dentinal tubule occlusion.

METHODS

Twelve freshly extracted intact human mandibular third molars were divided randomly into four groups. The superficial occlusal dentin of each tooth was exposed and treated. Group A1: One-Step Plus total-etch adhesive system; group A2: One-Step Plus total-etch adhesive system after fluoride iontophoresis; group B1: ACE BOND SE self-etching adhesive system; group B2: ACE BOND SE self-etching adhesive system after fluoride iontophoresis. A resin composite buildup was made for each tooth, which was then sectioned along its long axis to produce 10 beams (1.0 mm x 1.0 mm) for the microtensile bond strength (MTBS) test. Five dentin disks were cut in half and their occlusal surfaces etched with 6% citric acid. The test halves were treated with fluoride iontophoresis. Four SEM photomicrographs were taken from corresponding sites on each test and each non-treated control half-disk. Image-Pro Plus 4 software quantified the percentage of tubule occlusion. Data were analyzed using one-way ANOVA, chi(2)- and t-tests, with the probability level set at alpha=0.05.

RESULTS

The mean MTBS (MPa) for each group was, A1: 30.86 (S.D. 6.84); A2: 25.04 (8.49); B1: 19.22 (6.88); B2: 19.40 (6.92). There were significant differences among all groups (P < or = 0.02), except between groups B1 and B2 (P=0.92). Fluoride iontophoresis resulted in significantly increased dentinal tubule occlusion (P<0.001).

CONCLUSIONS

Fluoride iontophoresis treatment reduced significantly the dentin bond strength of One-Step Plus total-etch adhesive, but not that of ACE BOND SE self-etching adhesive. However, the bond strength of the former remained significantly higher than that of the latter adhesive system.

Leaching from glass ionomer cements

This study compared the electrical conductivities, pH and leached ion (F-, Ca, Al, Si) concentrations in supernatant liquids obtained from four glassionomer cements, a buffered ionomer cement, a polycarboxylate cement and a zinc phosphate cement, at three different levels of settings. The result indicated that the measured parameters are highest for the unset condition of cements and decreases as the set condition is approached, except for pH, which shows the opposite trend. Two pulp sensitive glassionomer cements, Chem Bond and Ketac Cem showed high Ca:F ratios as well as high Ca and F concentrations. Further, it is suggested that the cytotoxicity of leached F-, Si, Al and Zn at high concentration and at low pH may induce sensitivity in tooth structure.

Current strategies for dentist-applied treatment in the management of hypersensitive dentine

Few of the many dentist-applied treatments for dentine hypersensitivity meet the requirements of an ideal desensitizing agent'. This paper, although not exhaustive, covers methods that may be classified from simplest to most complex. Topical methods are simple, but they are often uncomfortable and the effects usually quite short-lasting, and many fall short of the 'ideal'. Fluorides and oxalates appear to be the best topical methods. Iontophoresis of fluoride represents an intermediate stage of complexity and it meets most of the criteria of an ideal desensitizing agent. Newer restorative materials, such as glass-ionomer cements and dentine bonding agents, are the most complex. These are still under investigation, but when the tooth needs recontouring, or in difficult cases that do not respond to other treatments, the dentist may choose to use a restorative material. Resin primers alone could be promising but the effects are not permanent and investigation into their use is still under way. Finally, laser treatment has been espoused for dentine desensitization. This requires extremely expensive equipment, must be dentist applied, and might produce pulpal irritation. Much more study is needed on restorative treatments and lasers before they can be considered as effective desensitizing agents. Until that research is completed, the dentist must choose one or more of the available methods in order to have a clinical therapy that is likely to relieve the symptoms of hypersensitive dentine.

Effectiveness of sodium fluoride on tooth hypersensitivity with and without iontophoresis

The purpose of this study was to assess the short and long term reduction of dentinal hypersensitivity by a single application of sodium fluoride with and without iontophoresis. Two teeth in each of 16 patients were blindly evaluated before and after treatment, and at 1, 3, and 6 months. A blast of air and tactile pressure were used to assess pain. Results indicate that there is significant, immediate reduction in dentinal hypersensitivity with the use of iontophoresis that is lost with time. The use of sodium fluoride alone had no effect. Sodium fluoride with iontophoresis was demonstrated to have an immediate post treatment effect (P less than .001) that lasted through the 3-month observation period. The data suggest that iontophoresis may be a useful adjunct to sensitivity therapy and that an immediate therapeutic effect may be achieved. The efficacy of the use of sodium fluoride alone is obscured by the natural reduction of root sensitivity observed with time.

Iontophoresis in dermatology. A review

Iontophoresis, the process of increasing the penetration of drugs into surface tissues by the application of an electric current, has been applied to a great many disease conditions over its 200-year history. Although its greatest success has been in the treatment of hyperhidrosis, it is steadily finding new applications. Many aspects of the mechanisms of iontophoresis have yet to be studied before the technic is both fully understood and maximally utilized. In this article we review the literature on iontophoresis as it pertains to dermatology, including the basic principles, engineering aspects.