Polymer Networks for Enrichment of Calcium Ions.

In this study, solvogels containing (2-((2-(ethoxycarbonyl)prop-2-en-1-yl)oxy)-ethyl) phosphonic acid (ECPA) and N,N'-diethyl-1,3-bis-(acrylamido)propane (BNEAA) as the crosslinker are synthesized by UV induced crosslinking photopolymerization in various solvents. The polymerization of the ECPA monomer is monitored by the conversion of double bonds with in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The morphology of the networks is characterized by in situ photorheology, solid state NMR spectroscopy, and scanning electron microscopy (SEM) of the dried gels. It is demonstrated that the storage modulus is not only determined by the crosslinker content in the gel, but also by the solvent used for preparation. The networks turn out to be porous structures with G' being governed by a rigid, phase-separated polymer phase rather than by entropic elasticity. The external and internal pKa values of the poly(ECPA-co-BNEAA) gels were determined by titration with a specially designed method and compared to the calculated values. The polymer-immobilized phosphonic acid groups in the hydrogels induce buffering behavior into the system without using a dissolved buffer. The calcium accumulation in the gels is studied by means of a double diffusion cell filled with calcium ion-containing solutions. The successful accumulation of hydroxyapatite within the gels is shown by a combination of SEM, energy-dispersive X-ray spectroscopy (EDX) and wide-angle X-ray scattering (WAXS).

Fluoride Varnishes--Is There a Correlation Between Fluoride Release and Deposition on Enamel?

PURPOSE: Fluoride uptake of enamel after application of fluoride varnishes was compared with fluoride release into artificial saliva. The hypothesis was that fluoride uptake is higher for products exhibiting faster fluoride release. MATERIALS AND METHODS: Fluoride varnishes, i.e. Fluor Protector S, Duraphat, MI Varnish, Clinpro White Varnish, Profluorid Varnish and Enamel Pro Varnish were applied on bovine enamel specimens. Subsequently, specimens were incubated in artificial saliva. After removal of the varnishes, surface bound fluoride was extracted with potassium hydroxide and measured with an ion-selective electrode. Structurally bound fluoride was etched from the same specimens with perchloric acid. Fluoride release of varnish films into artificial saliva was measured for comparison. RESULTS: After 4 h in artificial saliva, the highest total enamel fluoride uptake of 47.9 µg F·cm-² was found with Fluor Protector S, followed by Enamel Pro Varnish with 22.1 µg F·cm-². The other products ranged between 12-16 µg F·cm-². This was several times higher than the negative control. Fluoride uptake did not correlate with release into artificial saliva. During the first 4 h, Duraphat released the lowest and MI Varnish the highest amount of fluoride with 7.7 and 249 µg F·cm-², respectively. The fluoride uptake of these two products was not statistically different. CONCLUSION: Enamel fluoride uptake cannot be predicted from the fluoride release rate of a product. Hence, based on the results of this study, fluoride release into artificial saliva is no measure for the efficacy of a fluoride varnish.

Anti-candidal activity of genetically engineered histatin variants with multiple functional domains.

The human bodily defense system includes a wide variety of innate antimicrobial proteins. Histatins are small molecular weight proteins produced by the human salivary glands that exhibit antifungal and antibacterial activities. While evolutionarily old salivary proteins such as mucins and proline-rich proteins contain large regions of tandem repeats, relatively young proteins like histatins do not contain such repeated domains. Anticipating that domain duplications have a functional advantage, we genetically engineered variants of histatin 3 with one, two, three, or four copies of the functional domain by PCR and splice overlap. The resulting proteins, designated reHst3 1-mer, reHist3 2-mer, reHis3 3-mer and reHist3 4-mer, exhibited molecular weights of 4,062, 5,919, 7,777, and 9,634 Da, respectively. The biological activities of these constructs were evaluated in fungicidal assays toward Candida albicans blastoconidia and germinated cells. The antifungal activities per mole of protein increased concomitantly with the number of functional domains present. This increase, however, was higher than could be anticipated from the molar concentration of functional domains present in the constructs. The demonstrated increase in antifungal activity may provide an evolutionary explanation why such domain multiplication is a frequent event in human salivary proteins.

The Effectiveness of Systemp.desensitizer in the treatment of dentine hypersensitivity.

PURPOSE: This study reports the effectiveness of Systemp.desensitizer (Ivoclar Vivadent, Schaan, Liechtenstein), when used both with and without an acid-etch step, in the treatment of patients with dentine hypersensitivity in UK dental practices. MATERIALS AND METHODS: Ten general dental practitioners (GDPs) were selected from two practice-based research groups. The GDPs were each requested to use Systemp.desensitizer in the treatment of at least ten patients who presented with pain due to dentine hypersensitivity. Systemp.desensitizer was applied to the sensitive dentine area in strict accordance with the manufacturer's handling instructions, except that the patients were divided into two groups. For the first, group NE, the procedure was to isolate the tooth, gently blot it dry with cotton wool pellets, rub Systemp.desensitizer into the tooth for 20 seconds, then gently air-dry it. For the second, group E, the procedure was identical except that after isolation, the treatment area was etched for 15 seconds with 35% phosphoric acid. Patients were asked to complete a pro forma using a 10 cm visual analogue scale designed to provide details of the extent of their pain before treatment, 24 hours post-treatment, one week post-treatment, one month post-treatment, and three months post-treatment. The zero end of the scale was marked 'no pain' and the 10 cm end was marked 'extreme pain'. The percentage change in the patients' perception of their pain, relative to pretreatment, was calculated using repeated measures analysis and suitable follow-up confidence intervals for the mean changes in perceived pain. Comparisons were then made between the treatment groups NE and E. RESULTS: Ninety-one patients completed the first pro forma and 77 completed all the pro formas. Overall, there was a significant reduction in pain at each of the time points after treatment but the pattern of pain reduction across the two groups was different. In general, the non-etched group (group NE) saw an 'immediate' reduction in pain which was then fairly consistent across the longer term, whilst, in general, the etched group (group E) saw less reduction in pain 24 hours after treatment, and then further reduction in pain at both one week and one month after treatment. Thus the non-etched group experienced an early reduction whilst the etched group took longer to perceive a reduction in pain; however, there were no statistically significant differences between the reductions in pain scores between the two groups at any of the time points after treatment. CONCLUSION: It is concluded that Systemp.desensitizer was effective in reducing pain from dentine hypersensitivity in the patients treated, and this finding was unaffected by whether or not the tooth was acid-etched prior to application of the reagent.