Adhesion and whitening efficacy of P11-4 self-assembling peptide and HAP suspension after using NaOCl as a pre-treatment agent

Background This study evaluated the adhesion and whitening efficacy of a mixture of hydroxyapatite and P11-4 self-assembling peptide (HAP-peptide) on bovine enamel after pre-treatment with low-concentrated sodium hypochlorite (NaOCl). Methods Fifty-two caries-free bovine incisors were selected. 50 teeth were randomly allocated to five groups (n = 10). The first group was treated with a mixture of 6.25 wt% HAP and 5 ml P11-4 peptide, using NaOCl 3% as pre-treatment. Second, third and fourth groups were treated with 6.25 wt% HAP, 5 ml P11-4 peptide, and NaOCl 3%, respectively. In the fifth group, only water was applied (control group). The color of samples was measured using a spectrophotometer (USB4000-VIS-NIR-ES, Ostfildern, Germany). To evaluate color changes, ΔE values were statistically analyzed. Finally, adherence of HAP particles on two enamel surfaces with and without pre-treatment with NaOCl was analyzed with SEM. Results It was observed that the ΔE of the HAP-peptide suspension after pre-treatment with NaOCl was significantly stronger than the control group. In contrast, the overall color changes of separate applications of HAP, peptide, and NaOCl did not differ notably from the control group. SEM observations confirmed that pre-treatment with NaOCl resulted in a more pronounced coverage of HAP on the enamel surface. Conclusions Pre-treatment with a low-concentrated NaOCl enhanced the adherence of the HAP layer on the enamel surface, resulting in a stronger whitening effect

Distribution and Excretion of BisGMA in Guinea Pigs

Bisphenol-A-glycidyldimethacrylate (BisGMA) is used in many resin-based dental materials. It was shown in vitro that BisGMA was released into the adjacent biophase from such materials during the first days after placement. In this study, the uptake, distribution, and excretion of [14C]BisGMA applied via gastric and intravenous administration (at dose levels well above those encountered in dental care) were examined in vivo in guinea pigs to test the hypothesis that BisGMA reaches cytotoxic levels in mammalian tissues. [14C]BisGMA was taken up rapidly from the stomach and intestine after gastric administration and was widely distributed in the body following administration by each route. Most [14C] was excreted within one day as 14CO2. The peak equivalent BisGMA levels in guinea pig tissues examined were at least 1000-fold less than known toxic levels. The peak urine level in guinea pigs that received well in excess of the body-weightadjusted dose expected in humans was also below known toxic levels. The study therefore did not support the hypothesis

ER localized bestrophin1 activates Ca2+ dependent ion channels TMEM16A and SK4

Bestrophins form Ca2+ activated Cl- channels and regulate intercellular Ca2+ signaling1. We demonstrate that bestrophin 1 is localized in the endoplasmic reticulum (ER), where it physically interacts with stromal interacting molecule 1 (Stim1), the ER-Ca2+ sensor2,3. Intracellular Ca2+ transients in HEK293 cells elicited by stimulation of purinergic P2Y2-receptors were augmented but more transient after expression of hBest1, in contrast to dominant negative hBest1-R218C, which attenuated Ca2+ increase. The p21-activated protein kinase Pak2 was found to phosphorylate hBest1, thereby enhancing Ca2+ signaling and activation of Ca2+ dependent Cl- (TMEM16A)4 and K+ (SK4)5 channels. Lack of bestrophin 1 expression in respiratory epithelial cells of mBest1 knockout mice caused expansion of ER cisterns and induced Ca2+ deposits. We propose that hBest1 is important for Ca2+ handling of the ER store, probably by controlling the function of Stim1 and by acting as a counter-ion channel to balance transient membrane potentials occurring through inositol trisphosphate (IP3) induced Ca2+ release and refill of the ER-Ca2+ store. Thus bestrophin 1 controls activation of Ca2+ dependent ion channels by regulation of compartmentalized Ca2+ signaling

CFTR-beyond the airways : Recent findings on the role of the CFTR channel in the pancreas, the intestine and the kidneys

With increased longevity of patients suffering from cystic fibrosis, and widespread lung transplantation facilities, the sequelae of defective CFTR in other organs than the airways come to the fore. This minireview highlights recent scientific progress in the understanding of CFTR function in the pancreas, the intestine and the kidney, and explores potential therapeutic strategies to combat defective CFTR function in these organs

Tooth whitening with an experimental toothpaste containing hydroxyapatite nanoparticles

Background The aim of this study was to evaluate the postbrushing tooth-whitening effect of toothpaste containing hydroxyapatite nanoparticles (nano-HAPs). The impact of the concentration on the whitening performance of nano-HAP toothpaste was also investigated. Methods Two concentrations of nano-HAP (10 wt% and 1 wt%) were incorporated in nonabrasive toothpastes. Forty bovine incisors were randomly assigned into four groups: 10 wt% nano-HAP, 1 wt% nano-HAP, toothpaste without nano-HAP as a negative control and water as a blank control. Each tooth was treated with the toothpaste three times and hydrodynamic shear force (HSF) once. The teeth surfaces were observed by SEM after each application. Tooth color (L*, a* and b* values) was measured by a spectrophotometer, and color changes (△E, △L, △a and △b values) were calculated. Two-way mixed ANOVA was performed to evaluate the influence of the concentration and repeated application on the tooth-whitening effect of nano-HAP. Results We found that nano-HAP-treated enamel exhibited higher L* values and lower a* and b* values than the control groups (P < 0.05). The 10 wt% nano-HAP group showed significantly higher △E values than the 1 wt% nano-HAP group (P < 0.05). After three applications, the △E mean value of the 10 wt% nano-HAP group was 4.47. The △E and △L values were slightly reduced after HSF (P < 0.05). For both nano-HAP groups, HAP single crystallites and agglomerates were identified, and their sizes grew with nano-HAP reapplication. Conclusions In conclusion, nano-HAP toothpaste has a satisfying postbrushing whitening effect and good resistance to mechanical forces. The whitening effect seemed to be concentration-dependent

Adhesion and whitening effects of P11-4 self-assembling peptide and HAP suspension on bovine enamel

OBJECTIVES This study evaluated the adhesion and whitening effects of a combination of P11-4 self-assembling peptide and hydroxyapatite (peptide-HAP) on bovine enamel. METHODS Forty-six caries-free bovine teeth were selected, and 40 teeth were randomly allocated to one of five groups (n = 8). First, the effects of application frequency, exposure time, and storage in saliva on the whitening effects of an experimental low-concentrated peptide-HAP suspension (0.5 wt% HAP; Curodont, Credentis) were evaluated and compared with a commercial bleaching agent (VivaStyle Paint on Plus, VS, Ivoclar Vivadent). Tooth color was measured using a spectrophotometer (Gretag MacBeth), and color changes ΔE were statistically analyzed. Second, the effects of peptide-HAP concentration (low versus high: 6.25% HAP; Curodont Protect), and its interactions with saliva and postapplication restaining, were investigated. Third, enamel surfaces (n = 2) were treated with low concentration peptide-HAP and high-concentration peptide-HAP in polymeric and monomeric forms (Curodont Protect & Curodont Repair, Credentis) and analyzed by SEM. RESULTS The ΔE of the low-concentration peptide-HAP suspension did not differ from that of VS. Application frequency, exposure time, and storage in saliva did not have any significant impact on whitening efficacy of the peptide-HAP suspension. Increasing the concentration of the suspension did not promote overall ΔE. SEM observations confirmed the presence of the newly generated peptide and HAP on the enamel surface. CONCLUSIONS The peptide-HAP suspension is a mild tooth whitener, and the adhesion of peptide-HAP to enamel is concentration dependent. CLINICAL RELEVANCE This peptide-HAP suspension is effective in offsetting discoloration caused by restaining after treatment

The competition between enamel and dentin adhesion within a cavity: An in vitro evaluation of class V restorations

To gain more insight into the consequences of curing contraction within the tooth cavity, we assessed the margin behavior of 12 contemporary restorative systems in class V restorations with margins located on enamel and dentin after mechanical loading and water storage. Mixed class V cavities were prepared on extracted human molars and restored using five etch and rinse and seven self-etch adhesive systems with their corresponding composites. Marginal adaptation was evaluated by using a computer-assisted quantitative marginal analysis in a scanning electron microscope (SEM) on epoxy replicas before, after thermal and mechanical stressing and after 1year of water storage. The interactions of "testing conditions”, "adhesive-composite combination” and "tooth substrate” with "marginal adaptation” were evaluated by two-way ANOVA. Fatigue, stress and storage conditions had significant effects on the marginal adaptation. Only two groups (Optibond FL and G Bond) presented equal percentages of marginal adaptation on enamel and dentin; in the other groups, the rate of degradation was product dependent. All materials tested showed a distinct behavior on enamel and dentin. In addition to mechanical resistance and long-term stability, differences within materials also exist in their ability to simultaneously bond to enamel and denti

Charakterisierung von Sprayflammen mittels abbildender Laserspektroskopie

In dieser Arbeit wurde im Rahmen einer Zusammenarbeit mit der 'University of California at Berkeley' ein Zerstäuberbrenner entwickelt und mittels laserspektroskopischer Methoden untersucht. Er besteht aus einer kommerziell erhältlichen Spraydüse, welche von einem Hüllstrom aus Luft umgeben ist. In den Ethanol-Sprayflammen wurden zweidimensionale Verteilungen des OH-Radikals durch Laserinduzierte Fluoreszenz (LIF) nachgewiesen. Die Geschwindigkeit der Tropfen im Spray wurde mittels der Particle-Image-Velocimetry (PIV) bestimmt. Darüber hinaus wurde durch ein kombiniertes LIF-Streulicht- (Mie-Streuung) Verfahren der Sauterdurchmesser (SMD) des Sprays ermittelt