Amikacin sulphate loaded chitosan-diopside nanoparticles composite scaffold for infectious wound healing

A wound dressing material should inhibit infections that may occur at the wound site, and at the same time, it should enhance the healing process. In this study, we developed an amikacin sulphate (AK) incorporated chitosan (Ch) and Diopside nanoparticles composite dressing (Ch-nDE-AK) for controlling wound infection and healing. The diopside nanoparticles (nDE) were prepared using sol-gel synthesis and characterized using XRD, FT-IR, and FESEM. nDE shows a size range of 142 ± 31 nm through FESEM analysis. Later, the developed composite dressing was characterized using SEM, EDS, and FT-IR analysis. Ch-nDE-AK dressing possesses a porous nature that will aid in easy cell infiltration and proliferation. The swelling studies indicated the expansion capability of the scaffold when applied to the injured site. Ch-nDE-AK scaffold showed a 69.6 ± 8.2 % amikacin sulphate release up to 7 days, which indicates the sustained release of the drug from Ch-nDE-AK scaffold. The drug release data was subjected to various kinetics models and was observed to follow the Higuchi model. The scaffold showed antibacterial activity against ATCC strains of S. aureus and E. coli for 7 days by in vitro. Ch-nDE-AK scaffold also showed antibacterial activity against S. aureus and E. coli clinical strains in vitro. The ex vivo antibacterial study confirmed the antibacterial ability of Ch-nDE-AK scaffold against S. aureus and E. coli. Ch-nDE-AK scaffold also exhibits anti-biofilm activity against S. aureus and E. coli. The Ch-nDE-AK scaffold showed cytocompatibility and cell attachment to fibroblast cells. Additionally, the scratch assay using fibroblast cells confirmed the role of the nDE in the scaffold, helping in cell migration. Thus, the developed Ch-nDE-AK dressing can potentially be used to treat infectious wound healing.

An efficient eco-friendly adsorbent material based on waste copper slag-biomass ash geopolymer: dye sorption capacity and sustainable properties

The primary intent of the research is to comprehensively assess the environmental benefits and cost dynamics associated with the adsorption process of CS-RHA (Copper Slag and Rice Husk Ash) to produce a novel geopolymer adsorbent material for application in wastewater treatment. The geopolymer forms a polyiron sialate network under alkali activation by dissolving fayalite, and aluminium silicate to ferro-ferri silicate hydrate gel. The mechanical strength, leaching characteristics, and microstructure of the geopolymer were determined using XRD and FTIR, and magnetic properties by VSM as well surface properties were derived from BET surface area and zeta potential. Recognizing the critical role of sodium iron silicate hydrate (NFS) in the sorption of methylene blue (MB) dyestuff, batch experiments were carried out using different adsorbents. The results indicated that the dye removal efficiency increased from 60% in control samples (FS) to 98% for the blend (FS1) under different pH values. The data was found to fit with the nonlinear form of Freundlich isotherm and follow pseudo-second-order kinetics. The active adsorption sites were deduced as -O-Fe-O-Si-O-Na and Si-OH groups. The addition of RHA increases the adsorption capacity of the geopolymer in a short time through chemical adsorption. The significant negative surface charge promotes MB adsorption via improved electrostatic attraction. The spent adsorbents were recovered through magnetic separation with a retrieval rate of 80-85% and active sites were rejuvenated by calcination. Consequently, waste copper slag emerges as a promising adsorbent with minimum potential ecological risk and high effective recycling capacity.

Surface-Modified Diopside-Reinforced PCL Biopolymer Composites with Enhanced Interfacial Strength and Mechanical Properties for Orthopedic Applications

The phase separation of ceramics in a biopolymer matrix makes it challenging to achieve satisfactory mechanical properties required for orthopedic applications. It has been found that silane coupling agents can modify the surface of the bioceramic phase by forming a molecular bridge between the polymer and the ceramic, resulting in improved interfacial strength and adhesion. Therefore, in the present study, silane-modified diopside (DI) ceramic and ε-polycaprolactone (PCL) biopolymer composites were fabricated by injection molding method. The silane modification of DI resulted in their uniform dispersion in the PCL matrix, whereas agglomeration was found in composites containing unmodified DI. The thermal stability of the silane-modified DI-containing composites also increased. The Young's modulus of the composite containing 50% w/w DI modified by 3% w/w silane increased by 103% compared to composites containing 50% w/w unmodified DI. The biodegradation of the unmodified composites was significantly high, indicating their weak interfacial strength with the PCL matrix (p ≤ 0.001). The osteoconductive behavior of the composites was also validated by in vitro cell-material studies. Overall, our findings supported that the silane-modified composites have improved surface roughness, mechanical, and osteoconductive properties compared to the unmodified composite and have the potential for orthopedic applications.

Experimental and computational evidence of U(VI)-OH-Si(OH)4 complexes under alkaline conditions: Implications for cement systems

The complexation of uranyl hydroxides with orthosilicic acid was investigated by experimental and theoretical methods. Spectroluminescence titration was performed in a glovebox under argon atmosphere at pH 9.2, 10.5 and 11.5, with [U(VI)] = 10-6 and 5 × 10-6 mol kgw-1. The polymerization effects of silicic acid were minimized by ruling out samples with less than 90 % monomeric silicic acid present, identified via UV-Vis spectrometry using the molybdate blue method. Linear regression analysis based on time-resolved laser-induced fluorescence spectroscopy (TRLFS) results yielded the conditional stepwise formation constants of U(VI)-OH-Si(OH)4 complexes at 0.05 mol kgw-1 NaNO3. The main spectroscopic features - characteristic peak positions and decay-time - are reported for the first time for the UO2(OH)2SiO(OH)3- species observed at pH 9.2 and 10.5 and UO2(OH)2SiO2(OH)22- predominant at pH 11.5. Quantum chemical calculations successfully computed the theoretical luminescence spectrum of the complex UO2(OH)2SiO(OH)3- species, thus underpinning the proposed chemical model for weakly alkaline systems. The conditional stability constants were extrapolated to infinite dilution using the Davies equation, resulting in log10β°(UO2(OH)2SiO(OH)3-) and log10β°(UO2(OH)2SiO2(OH)22-). Implications for U(VI) speciation in the presence and absence of competing carbonate are discussed for silicate-rich environments expected in certain repository concepts for nuclear waste disposal.

Oral Excretion Kinetics of Food-Additive Silicon Dioxides and Their Effect on In Vivo Macrophage Activation

A food additive, silicon dioxide (SiO2) is commonly used in the food industry as an anti-caking agent. The presence of nanoparticles (NPs) in commercial food-grade SiO2 has raised concerns regarding their potential toxicity related to nano size. While recent studies have demonstrated the oral absorption and tissue distribution of food-additive SiO2 particles, limited information is available about their excretion behaviors and potential impact on macrophage activation. In this study, the excretion kinetics of two differently manufactured (fumed and precipitated) SiO2 particles were evaluated following repeated oral administration to rats for 28 d. The excretion fate of their intact particles, decomposed forms, or ionic forms was investigated in feces and urine, respectively. Monocyte uptake, Kupffer cell activation, and cytokine release were assessed after the oral administration of SiO2 particles. Additionally, their intracellular fates were determined in Raw 264.7 cells. The results revealed that the majority of SiO2 particles were not absorbed but directly excreted via feces in intact particle forms. Only a small portion of SiO2 was eliminated via urine, predominantly in the form of bioconverted silicic acid and slightly decomposed ionic forms. SiO2 particles were mainly present in particle forms inside cells, followed by ionic and silicic acid forms, indicating their slow conversion into silicic acid after cellular uptake. No effects of the manufacturing method were observed on excretion and fates. Moreover, no in vivo monocyte uptake, Kupffer cell polarization, or cytokine release were induced by orally administered SiO2 particles. These finding contribute to understanding the oral toxicokinetics of food-additive SiO2 and provide valuable insights into its potential toxicity.

Antiscalants for mitigating silica scaling in membrane desalination: Effects of molecular structure and membrane process

Silica scaling is a major type of mineral scaling that significantly constrains the performance and efficiency of membrane desalination. While antiscalants have been commonly used to control mineral scaling formed via crystallization, there is a lack of antiscalants for silica scaling due to its unique formation mechanism of polymerization. In this study, we performed a systematic study that investigated and compared antiscalants with different functional groups and molecular weights for mitigating silica scaling in membrane distillation (MD) and reverse osmosis (RO). The efficiencies of these antiscalants were tested in both static experiments (for hindering silicic acid polymerization) as well as crossflow, dynamic MD and RO experiments (for reducing water flux decline). Our results show that antiscalants enriched with strong H-accepters and H-donors were both able to hinder silicic acid polymerization efficiently in static experiments, with their antiscaling performance being a function of both molecular functionality and weight. Although poly(ethylene glycol) (PEG) with abundant H-accepters exhibited high antiscaling efficiencies during static experiments, it displayed limited performance of mitigating silica scaling during MD and RO. Poly (ethylene glycol) diamine (PEGD), which has a PEG backbone but is terminated by two amino groups, was efficient to both hinder silicic acid polymerization and reduce water flux decline in MD and RO. Antiscalants enriched with H-donors, such as poly(ethylenimine) (PEI) and poly(amidoamine) (PAMAM), were effective of extending the water recovery of MD but conversely facilitated water flux decline of RO in the presence of supersaturated silica. Further analyses of silica scales formed on the membrane surfaces confirmed that the antiscalants interacted with silica via hydrogen bonding and showed that the presence of antiscalants governed the silica morphology. Our work indicates that discrepancy in antiscalant efficiency exists between static experiments and dynamic membrane filtration as well as between different membrane processes associated with silica scaling, providing valuable insights on the design principle and mechanisms of antiscalants tailored to silica scaling.

Deciphering the diversity and distribution of chromophytic phytoplankton in the Bohai Sea and the Yellow Sea via RuBisCO genes (rbcL)

Present study investigated composition and distribution of chromophytic phytoplankton in the Bohai Sea (BS) and the Yellow Sea (YS) by using rbcL genes. Bacillariophyceae, Haptophyceae and Pelagophyceae were the most abundant phytoplankton groups. Distinct phytoplankton communities were observed in the BS and the YS: offshore stations were dominated by bloom forming genera Thalassiosira and Skeletonema, while brown tide-forming species including Chrysochromulina spp. and Aureococcus anophagefferens were commonly found in the nearshore areas. Redundancy analysis showed that phosphate, temperature and silicic acid play key roles in structuring chromophytic phytoplankton, such as phytoplankton at nearshore stations were affected by nutrient runoff from adjacent rivers (Yellow River). Anthropogenic activities in the Bohai Sea and seasonal circulation of ocean currents may also contribute to shaping chromophytic phytoplankton communities. This study provides data support and foundational observations of chromophytic phytoplankton in the BS and the YS, and their responses to environmental gradients and human activities.

Phytochemical Composition, Antibacterial, Antioxidant and Antidiabetic Potentials of Cydonia oblonga Bark

Cydonia oblonga is a medicinal plant that is used to treat a number of health complications in traditional medication systems. The objective of this study was to evaluate the phytochemical composition, and antibacterial, antioxidant, and ant-diabetic potentials of methanolic extracts of Cydonia oblonga bark. The Cydonia oblonga bark extraction was fractionated through HPLC and seven purified fractions labeled as F1, F2, F3, F4, F5, F6, and F7 were obtained. The HPLC-UV analysis of methanolic extract showed the presence of a number of possible compounds. The GC-MS and HPLC analysis confirmed the presence of the following bioactive compounds in the crude extract and purified fractions: malic acid, mandelic acid, quercetin, caffeic acid, catechin hydrate, as morin (HPLC analysis), BIS-(2-ethylhexyl)phthalate and diisooctyl phthalate (F1), carbamide (F2, used as fertilizer), octasiloxane and dimethylsiloxanecyclictrimer (F3), silicic acid and cyclotrisiloxane (F4), 6-AH-cAMP, 4H-cyclopropa[5′,6′]benz[1′,2′,7,8]azule, and 4-(4-chlorophenyl)-3-morpholinepyrol-2-yl)-butenedioic acid (F5), isopropyamine (F6), and 1-propylhydrazine (F7). The extract and purified fractions were then tested for biological activities. All the purified fractions and methanolic extract showed effective antibacterial activity; however, the highest activity was recorded for methanolic extract against Staphylococcus aureus and Streptococcus pneumonia. Antioxidant evaluation of methanolic extract and purified fractions against DPPH showed strong % inhibition of the synthetic free radical. The methanolic extract exhibited 87.41 ± 0.54% inhibition whereas fractions showed: F1, 85.45 ± 0.85; F2, 65.78 ± 0.68; F3, 58.61 ± 0.58; F4, 80.76 ± 0.59; F5, 571.29 ± 0.49; F6, 85.28 ± 0.94; and F7, 48.45 ± 0.62% inhibition. Ascorbic acid (standard) was used as a control with 94.88 ± 0.56% inhibition at a maximum concentration of 1000 µg/mL. The α-glucosidase inhibition assay of methanolic extract and purified fractions at a maximum concentration of 1000 µg/mL showed activities as: methanolic extract, 78.21 ± 0.67; F1, 55.01 ± 0.29; F2, 56.10 ± 0.24; F3, 62.44 ± 1.03; F4, 70.52 ± 0.15; F5, 62.18 ± 0.92; F6, 72.68 ± 0.2; and F7, 57.33 ± 0.05% inhibition. α-Amylase % inhibition of methanolic extract and purified fractions were noted as: methanolic extract, 77.98 ± 0.57; F1, 79.72 ± 0.02; F2, 79.72 ± 0.02; F3, 82.16 ± 0.48; F4, 77.37 ± 0.28; F5, 72.14 ± 0.30; F6, 74.24 ± 0.29; and F7, 56.58 ± 0.10 at the highest concentration of 1000 µg/mL. Acarbose (standard) showed 87.65 ± 0.71% inhibition of α-glucosidase and 85.99 ± 0.44% inhibition of α-amylase at the highest concentration of 1000 µg/mL. It was found that all biological activities of methanolic extract and purified fractions might be attributed to the fact that they are rich sources of phenolic and flavonoids along with other bioactive compounds. The total phenolic and flavonoid contents of methanolic extract were recorded higher as compared to purified fractions (TPC = 70% and TFC = 69%). Amongst the purified fractions, fraction 6 exhibited the highest TPC value (64%), and purified fraction 1 exhibited the highest value of TFC (58%). Recent research demonstrated that Cydonia oblonga may be considered an antibacterial medicinal plant. The result of the present study revealed that it might be utilized for the isolation of bioactive phytochemicals that can lead to new opportunities in the discovery of new antibiotics.

Lysozyme is Sterically Trapped Within the Silica Cage in Bioinspired Silica-Lysozyme Composites: A Multi-Technique Understanding of Elusive Protein-Material Interactions

Lysozyme is widely known to promote the formation of condensed silica networks from solutions containing silicic acid, in a reproducible and cost-effective way. However, little is known about the fate of the protein after the formation of the silica particles. Also, the relative arrangement of the different components in the resulting material is a matter of debate. In this study, we investigate the nature of the protein-silica interactions by means of solid-state nuclear magnetic resonance spectroscopy, small-angle X-ray scattering, and electron microscopy. We find that lysozyme and silica are in intimate contact and strongly interacting, but their interaction is neither covalent nor electrostatic: lysozyme is mostly trapped inside the silica by steric effects.

Multi-component removal of Pb(II), Cd(II), and As(V) over core-shell structured nanoscale zero-valent iron@mesoporous hydrated silica

The application of nanomaterials for the removal of heavy metals has received a great deal of attention because of their high efficiencies in the environment. But it is difficult to remove multiple heavy metals simultaneously with high efficiency and stability. Herein, the core-shell structured nanoscale zero-valent iron (nZVI) encapsulated with mesoporous hydrated silica (nZVI@mSiO₂) were prepared for efficient removal of heavy metals including Pb(II), Cd(II), and metalloid As(V). The material prepared uniformly with a high surface area (147.7 m² g^-1) has a nZVI core with the particle size of 20-60 nm and a modified dendritic mesoporous shell of 19 nm. 0.15 g L^-1 of the optimal material exhibited an extraordinary performance on removing Cd(II) and the maximum adsorption capacity for Pb(II), Cd(II), and As(V) reached 372.2 mg g^-1, 105.2 mg g^-1, and 115.2 mg g^-1 with a pH value at 5.0, respectively. The dissolved iron during the reaction showed that the mesoporous silica (mSiO₂) played an important role in enhancing the stability of nZVI. In addition, the competitive relationship between the coexistence of two heavy metals was discussed and it was found that the removal efficiency of the material for both was improved when Cd(II) and As(V) were removed synergistically.

Abatement of hydrated silica, arsenic, and coexisting ions from groundwater by electrocoagulation using iron electrodes

The paper deals with the removal of arsenic (As), hydrated silica (HS), and coexisting ions from groundwater by electrocoagulation (EC) using a laboratory-scale up-flow reactor with sacrificial iron anodes (1018 steel, >99% wt. Fe). Natural groundwater, taken in the northern region of Mexico, contained 25.7 μg L^-1 As, 237.8 mg L^-1 HS, 1.43 mg L^-1 F^-, 45.0 mg L^-1 SO₄^2-, 0.61 mg L^-1 PO₄^3-, pH 8.62, and 577 μS cm^-1 conductivity. The effect of current densities (4≤j≤8 mA cm^-2) and mean linear flow velocities (1.1≤u≤4.6 cm s^-1) on the pollutant's removal was systematically addressed. The best EC trial that showed the lowest overall cost and complied with the WHO guideline (<10 μg L^-1 As) was obtained at j = 6 mA cm^-2 and u = 2.3 cm s^-1, reaching residual concentrations of As and HS of 4.6 μg L^-1 and 150.0 mg L^-1, respectively. A large amount of HS was found after electrolysis; therefore, a second EC was applied to reduce the HS concentration further. This time, residual concentrations of HS and As of 37.0 mg L^-1 and 1.2 μg L^-1 were obtained, with electrolytic energy consumption and overall cost of EC of 0.872 kWh m^-3 and 0.178 USD m^-3, respectively. XRF, EDS, XRD, and FTIR analyzes on flocs indicate that hydrated silica reacts with iron, forming iron silicates with divalent cations as flocs. Arsenic and PO₄^3- are abated by adsorption on flocs. The modest removal of F^- and SO₄^2- (44% and 12%, respectively) is due to its weak adsorption on flocs.

Improvement of On-Site Sensor for Simultaneous Determination of Phosphate, Silicic Acid, Nitrate plus Nitrite in Seawater

Accurate, on-site determinations of macronutrients (phosphate (PO₄^3-), nitrate (NO₃^-), and silicic acid (H₄SiO₄)) in seawater in real time are essential to obtain information on their distribution, flux, and role in marine biogeochemical cycles. The development of robust sensors for long-term on-site analysis of macronutrients in seawater is a great challenge. Here, we present improvements of a commercial automated sensor for nutrients (including PO₄^3-, H₄SiO₄, and NO₂^- plus NO₃^-), suitable for a variety of aquatic environments. The sensor uses the phosphomolybdate blue method for PO₄^3-, the silicomolybdate blue method for H₄SiO₄ and the Griess reagent method for NO₂^-, modified with vanadium chloride as reducing agent for the determination of NO₃^-. Here, we report the optimization of analytical conditions, including reaction time for PO₄^3- analysis, complexation time for H₄SiO₄ analysis, and analyte to reagent ratio for NO₃^- analysis. The instrument showed wide linear ranges, from 0.2 to 100 μM PO₄^3-, between 0.2 and 100 μM H₄SiO₄, from 0.5 to 100 μM NO₃^-, and between 0.4 and 100 μM NO₂^-, with detection limits of 0.18 μM, 0.15 μM, 0.45 μM, and 0.35 μM for PO₄^3-, H₄SiO₄, NO₃^-, and NO₂^-, respectively. The analyzer showed good precision with a relative standard deviation of 8.9% for PO₄^3-, 4.8% for H₄SiO₄, and 7.4% for NO₂^- plus NO₃^- during routine analysis of certified reference materials (KANSO, Japan). The analyzer performed well in the field during a 46-day deployment on a pontoon in the Kiel Fjord (located in the southwestern Baltic Sea), with a water supply from a depth of 1 m. The system successfully collected 443, 440, and 409 on-site data points for PO₄^3-, Σ(NO₃^- + NO₂^-), and H₄SiO₄, respectively. Time series data agreed well with data obtained from the analysis of discretely collected samples using standard reference laboratory procedures and showed clear correlations with key hydrographic parameters throughout the deployment period.

Fluorosilicic acid and cotinine, separately and in combination, induce genotoxicity and telomeric reduction in human osteoblast cell line MG63

Skeletal fluorosis is a severe case in which bone deformations and bone tissue weakening occur due to excessive fluorine deposition. Recently, data on smoking have been published that smoke constituents can indirectly influence bone mass and interfere in the metabolism of fluorides in humans. Thus, the present in vitro study aimed to assess the genetic instability in human osteoblast MG63 cells exposed to fluorosilicic acid (FA) and cotinine (COT), separately and in combination, in concentrations found in human plasma. For this, cell cytotoxicity was performed by MTT assay; DNA damage was performed by alkaline comet assay (CA), modified by repair endonucleases (+FPG); micronuclei test (MN) using CBMN-Cyt assay; and telomere length (TL) by qPCR in MG63 cells. No cytotoxicity was observed for all concentrations tested in this study. Alkaline CA results showed a significant increase in DNA damage at all FA concentrations (0.03125-0.300 mg/L), in the two highest concentrations of COT (125 and 250 ng/mL), and the highest concentration of FA+COT (0.300 mg/L+250 ng/mL). Alkaline CA+FPG test was used to detect oxidized nucleobases, which occurred at the two highest concentrations of FA, COT, and FA+COT. Micronuclei test showed an increase in the frequency of MN at all concentrations of FA (0.075-0.300 mg/L) except in the lowest concentration (0.03125 mg/L), in the two highest concentrations of COT (125 and 250 ng/mL), and all concentrations of FA+COT. There was no significant difference in nuclear division index, binucleated cells, nucleoplasmic bridge, and nuclear bud. A TL reduction was observed in cells treated with the highest concentrations of FA alone (0.300 mg/L) and FA+COT (0.300 mg/L+250 ng/mL). Finally, our study showed that FA and COT (mainly alone) at concentrations found in human plasma induced oxidative damage and genetic instability in human osteoblast cells.

Ortho-silicic Acid Inhibits RANKL-Induced Osteoclastogenesis and Reverses Ovariectomy-Induced Bone Loss In Vivo

Numerous experiments in vitro and in vivo have shown that an appropriate increase intake of silicon can facilitate the synthesis of collagen and its stabilization and promote the differentiation and mineralization of osteoblasts. In this study, we examined whether ortho-silicic acid restrains the differentiation of osteoclast through the receptor activator of nuclear factor κB ligand (RANKL)/receptor activator of nuclear factor κB (RANK)/osteoprotegerin (OPG) signaling pathway by investigating its effect in vitro and in vivo. Bone marrow macrophage (BMM) cells were isolated and cultured with or without ortho-silicic acid, and then TRAP staining and immunofluorescence were performed to detect the differentiation of osteoclast. The RANKL-induced osteoclast marker gene and protein expression including c-Fos, nuclear factor of activated T cells cl (NFATcl), tumor necrosis factor receptor-associated factor 6 (TRAF6), nuclear factor kappa B P50 (NF-κB P50), NF-κB P52, RANK, integrin β3, cathepsin K (CTSK), DC-STAMP, and TRAP were quantitatively detected by western blot and RT-PCR. Ovariectomized (OVX) rats were injected with ortho-silicic acid (OVX+Si group) and normal saline (OVX group), and sham-operated rats were injected with normal saline (Sham group). And micro-CT, H&E, and TRAP staining, ELISA, and western blot were performed. Ortho-silicic acid could inhibit the differentiation of osteoclast, and the marker genes and proteins were decreased. The OVX-induced bone loss could be reversed by ortho-silicic acid. Our finding demonstrated that ortho-silicic acid suppresses RANKL-induced osteoclastogenesis and has potential value as a therapeutic agent for OVX-induced bone loss.

Iron reduction and diopside-based glass ceramic preparation based on mineral carbonation of steel slag

In this article, a new process for treating steel slag and CO₂ simultaneously and preparing calcium carbonate, metallic iron, and glass ceramics without wastewater or gas production is proposed. The reduction of iron and preparation of diopside glass ceramics are studied in this paper, and the results show that the carbon thermal reduction product of the original slag does not reach its melting point, and the slag and iron are well separated in the samples containing the leached steel slag and added silica. Part of the parent glass is converted into a glass ceramic after heat treatment, and the crystalline phases of samples are melilite, diopside, and partial melilite, and diopside and anorthite, respectively. The crystallization activation energy of the best sample in this article is E = 660.664 kJ/mol. The Avrami indices calculated at different heating rates are all less than 3, which indicates that the crystallization mode of the glass involves surface crystallization. This finding is consistent with the results for the prepared glass ceramics.

The Probable Mechanism for Silicon Capture by Diatom Algae: Assimilation of Polycarbonic Acids with Diatoms-Is Endocytosis a Key Stage in Building of Siliceous Frustules?

Many organisms including unicellular (diatoms, radiolaria, and chrysophytes), higher plants (rice and horsetail) and animals (sponges) use silica as a main part of skeletons. The bioavailable form of silicon is silicic acid and the mechanism of silicic acid penetration into living cells is still an enigma. Macropinocytosis was assumed as a key stage of the silicon capture by diatoms but assimilation of monomeric silicic acid by this way requires enormous amounts of water to be passed through the cell. We hypothesized that silicon can be captured by diatoms via endocytosis in the form of partially condensed silicic acid (oligosilicates) whose formation on the diatom surface was supposed. Oligosilicates are negatively charged nanoparticles and similar to coils of poly(acrylic acid) (PAA). We have synthesized fluorescent tagged PAA as well as several neutral and positively charged polymers. Cultivation of the diatom Ulnaria ferefusiformis in the presence of these polymers showed that only PAA is able to penetrate into siliceous frustules. The presence of PAA in the frustules was confirmed with chromatography and PAA causes various aberrations of the valve morphology. Growth of U. ferefusiformis and two other diatoms in the presence of tri- and tetracarbonic fluorescent tagged acids points to the ability of diatoms to recognize substances that bear four acidic groups and to include them into siliceous frustules. Thus, partial condensation of silicic acid is a plausible first stage of silicon assimilation.

Identification of the Domains Involved in Promotion of Silica Formation in Glassin, a Protein Occluded in Hexactinellid Sponge Biosilica, for Development of a Tag for Purification and Immobilization of Recombinant Proteins

Glassin, a protein occluded in biosilica of the hexactinellid sponge Euplectela, promotes silica formation from silicic acid at room temperature and neutral pH and is characterized by its primary structure which consists of a tandem repeat carrying three distinct domains, histidine and aspartic acid-rich (HD) domain, proline-rich (P) domain, and histidine and threonine-rich (HT) domain. The present study aims to clarify the domain responsible for the promotion of silica formation and to demonstrate usefulness of glassin and its domain as a tag for purification and immobilization of recombinant proteins. When each domain was mixed with silicic acid at neutral pH, silica was formed with HD domain as well as glassin, or a single repeat, but not with P or HT domain. Neither of amino or carboxy-terminal half of HD domain induced silica formation. The amount of silica formed with HD domain was significantly lower than that of glassin or a single repeat. HD domain fused with HT domain raised the amount of silica formed, while a HD domain fused with P domain, a mixture of HD and P domains, or a mixture of HD and HT domains has little effect on the promotion of silica formation. Collectively, a minimum sequence for promotion of silica formation is HD domain, whose activity can be enhanced by HT domain through a topological effect. In addition, practicality of glassin and HD domain was demonstrated by fusion of these sequences to green fluorescent protein which was successfully purified with Ni affinity chromatography and immobilized on silica.

Stabilized Ortho-Silicic Acid as a Modifier of Tissue-Preliminary Comparative Biomaterial Studies

The ortho-silicic acid (H₄SiO₄) plays an essential role in delivering silicon to body cells and the monomeric ortho-silicic acid is the most bioavailable source of silicon for humans. This study reveals that the ortho-silicic acid (OSA) modifies the tissue of a healthy and pathological hypotrophic amnion, thermal burn skin and, additionally, the OSA-incubated serum. Changes in the tissue modified by the ortho-silicic acid were traced on the molecular level with the use of FTIR spectroscopy. The most interesting area of tissue modification with the use of OSA acid solutions is the appearance of the 1085 cm^-1 Si-O-Si band which is optimal for the 1:6000 OSA concentration. Microbiological studies aiming at anticipating anti-inflammatory and antibacterial bioactivity revealed that the skin samples and amniotic samples were characterised by good resistance to the following bacteria: Enterococcus faecalis, Staphylococcus aureus and Escherichia coli (medium growth inhibition zone: 0.5-4 mm). The present study determined the concentration and the composition of the solutions to be used in the future to create innovative modifiers (active dressings or new dietary supplements) enhancing tissue regeneration.

Colloidal Dynamics of Freshly Formed Iron Oxides under the Influence of Silicic Acid

Silicic acid and soluble Fe are among the most abundant components in acid mine drainage. During the oxidation of Fe(II), the interaction between silicic acid and freshly formed Fe oxides might change the colloidal dynamics, altering surface charge properties. However, the effects of silicic acid on colloidal Fe oxides formed from acid mine drainage are not fully understood. In this work, we examined the colloidal dynamics of freshly formed Fe oxides in synthetic acid mine drainage (prepared from FeSO solution) under the effect of silicic acid as a function of changes in pH and ionic strength. The results demonstrate that through adsorption, silicic acid progressively slows oxidation and enhances the dispersion of freshly formed Fe oxides by shifting the surface charge toward more negative values. This effect was most prominent between pH 5 and 9. The current results demonstrate that silicic acid enhances the dispersion and transport of freshly formed Fe oxides and suggest that aggregation-based techniques for the treatment of Fe-rich drainage may require further consideration of this effect.

A Clinical Investigation of the Efficacy of a Dual Zinc plus Arginine Dentifrice for Controlling Oral Malodor

OBJECTIVES

The objective of this independent, double-blind clinical study was to assess the efficacy of a new Dual Zinc plus Arginine dentifrice (Colgate-Palmolive Co., New York, NY, USA) containing zinc (zinc oxide, zinc citrate) 0.96%, 1.5% arginine, and 1450 ppm F as sodium fluoride in a silica base for the 12-hour overnight oral malodor reduction after three weeks of product use, relative to that of a regular fluoride dentifrice containing 1450 ppm F as sodium fluoride in a silica base (Colgate-Palmolive Co., New York, NY, USA).

METHODS

A total of eighty (80) adult male and female subjects from Chengdu, People's Republic of China, were enrolled in this clinical study. Following an assessment of the oral soft and hard tissues, subjects were evaluated for baseline oral malodor by a panel of four trained and calibrated judges using a nine-point organoleptic hedonic scale. They were then randomly assigned to one of two treatment groups (Dual Zinc plus Arginine - test; regular fluoride dentifrice - control). Subjects were provided with their assigned dentifrice and toothbrush and instructed to brush their teeth twice daily (morning and evening) for one minute. After three weeks, subjects returned to the study site for their follow-up evaluation of malodor after having refrained from brushing for 12 hours (overnight).

RESULTS

Eighty (80) subjects completed the study. After three weeks of product use, subjects in the Dual Zinc plus Arginine dentifrice group and the regular fluoride dentifrice group showed statistically significant (p < 0.001) reductions of 38.9% and 11.6%, respectively, in organoleptic scores as compared to baseline. Relative to the regular fluoride dentifrice group, subjects in the Dual Zinc plus Arginine dentifrice group exhibited a statistically significant (p< 0.001) reduction of 30.8% in oral malodor. The quality of breath for subjects in the Dual Zinc plus Arginine dentifrice group was in the range corresponding to pleasant breath, whereas the quality of breath for subjects in the regular fluoride dentifrice group was in the range corresponding to unpleasant breath.

CONCLUSIONS

The overall results of this double-blind clinical study support the conclusion that a new Dual Zinc plus Arginine dentifrice containing zinc (zinc oxide, zinc citrate) 0.96%, 1.5% arginine, and 1450 ppm fluoride as sodium fluoride in a silica base provides a significantly greater reduction in oral malodor as compared to a regular fluoride dentifrice containing 1450 ppm fluoride as sodium fluoride in a silica base 12 hours post-brushing (overnight) after 3 weeks of product use.

A Note on the Analysis of Oil of Peppermint by an Aluminium Oxide-Silicic Acid Double Column

The separation and determination of the constituents of oil of peppermint have been effected using two columns in succession, one consisting of aluminium oxide and the other of silicic acid.

Effect of MgO contents on the mechanical properties and biological performances of bioceramics in the MgO-CaO-SiO2 system

The aim of this research was to investigate the effect of the chemical composition on the mechanical properties, bioactivity, and cytocompatibility in vitro of bioceramics in the MgO-CaO-SiO(2) system. Three single-phase ceramics (merwinite, akermanite and monticellite ceramics) with different MgO contents were fabricated. The mechanical properties were tested by an electronic universal machine, while the bioactivity in vitro of the ceramics was detected by investigating the bone-like apatite-formation ability in simulated body fluid (SBF), and the cytocompatibility was evaluated through osteoblast proliferation and adhesion assay. The results showed that their mechanical properties were improved from merwinite to akermanite and monticellite ceramics with the increase of MgO contents, whereas the apatite-formation ability in SBF and cell proliferation decreased. Furthermore, osteoblasts could adhere, spread and proliferate on these ceramic wafers. Finally, the elongated appearance and minor filopodia of cells on merwinite ceramic were more obvious than the other two ceramics.

The use of the Modified Gingival Margin Plaque Index (MGMPI) method to investigate the inhibitory effect of various toothpastes on dental plaque formation

OBJECTIVE

Colgate Total (CTT) is the only FDA-approved toothpaste for antiplaque and antigingivitis benefits. The objective of this study was to compare the impact of Colgate Total Pharma (CTP), a new variant of Colgate Total, with Colgate Regular Toothpaste (CRT) on plaque formation over a 24-hour period following a single use of the dentifrice.

METHODS

CTP and CRT were the two test products. CRT was used for a washout product as well. Fifteen male/female subjects who met the inclusion/exclusion criteria were included into this single-blind (preliminary phase) and double-blind (randomized phase) crossover study. Ethical approval and written informed consent were obtained. Preliminary phase: After a one-week washout with CRT, subjects brushed in the dental clinic with CRT before a one-minute use of a test dentifrice. A baseline Modified Gingival Margin Plaque Index (MGMPI) score was calculated. Subjects refrained from oral hygiene for 24 hours, and returned to the clinic for their 24-hour MGMPI score. Subjects entered the second washout phase to repeat as per the crossover design. The above procedures were conducted three times by three independent examiners. Randomized phase: Subjects were randomized to the groups according to a computer-generated randomization schedule. The procedure was carried out as in the preliminary phase, except the washout period between the two products was at least one week and the products (CTP or CRT) were used in a randomized double-blind manner. Plaque scores were recorded as above.

RESULTS

CTP provided a significant (p = 0.01) antiplaque effect versus CRT. The results are consistent with previously reported data for CTT. All three examiners demonstrated a strong correlation for this clinical study utilizing the MGMPI methodology.

CONCLUSION

This clinical investigation examined the efficacy of a new variant of a commercial dentifrice, historically shown to provide antiplaque and antigingivitis efficacy. It is important to confirm the continued efficacy of new products to consumers and to the profession. Additionally, this clinical trial demonstrated the usefulness of the clinical methodology with respect to consistency in results by three independent clinical examiners. Because this methodology is often employed to document antiplaque benefits of new and existing technologies, it is important to periodically evaluate and confirm its reliability and reproducibility.

Mechanism of action of a desensitizing fluoride toothpaste delivering calcium and phosphate ingredients in the treatment of dental hypersensitivity. Part II: comparison with a professional treatment for tooth hypersensitivity

Tooth hypersensitivity can occur when gum recession causes exposure of dentin. Tiny tubules, which permeate dentin, provide open passageways from the mouth to the intradental nerve in the pulpal cavity. Under such circumstances, stimuli in the mouth can cause pressure on the intradental nerve, leading to pain. Sealing the outside of the tubules with an impermeable substance can effectively treat hypersensitivity. One such clinically proven composition is a professionally applied tooth desensitizer, which has been shown to initially produce a layer of amorphous calcium phosphate (ACP) on the surface of dentin. Under the influence of fluoride, ACP reforms as hydroxyapatite (HAP), which has essentially the same composition as tooth mineral. Three fluoride toothpastes that deliver calcium and phosphate salts to the teeth also have been demonstrated in clinical trials to relieve hypersensitivity. This study compared the mechanism of action of these toothpastes to that of the professional desensitizer. A single application of the professional desensitizer or multiple applications of any of the three toothpastes was shown to reduce dentin permeability. A conventional fluoride toothpaste also was found to inhibit fluid flow through the dentin but to a lesser degree than the other toothpastes. The desensitizer and the three toothpastes were found to occlude the dentinal tubules with a layer of calcium phosphate that had a calcium-to-phosphate ratio consistent with the formation of ACP or HAP. The morphology of the coherent mineral layer formed by Arm & Hammer Enamel Care Sensitive was similar, especially to that produced by the desensitizer. In contrast, the conventional toothpaste left localized areas of surface residue composed of silica particles. The mechanism of action of the three toothpastes that deliver calcium and phosphate salts is the same as that of the professional desensitizer.

Toothpaste use by children, oral hygiene, and nutritional education: an assessment of parental performance

PURPOSE

The aim of this study was to determine oral health habits and educational needs of children as reported by their parents or guardians attending a health fair in West Virginia.

METHODS

Parents and/or guardians completed a questionnaire about the oral hygiene care, food and beverage consumption of their children. They also demonstrated the amount of toothpaste applied to their children's toothbrush. Toothpaste samples were then weighed.

RESULTS

Eighty-seven parents or guardians participated. An average of 0.53 mg of toothpaste was dispensed per brushing, almost double the recommended amount. Most of the parents or guardians (75%) indicated their children had brushed twice the day prior to completing the questionnaire. Only 21% reported that their children's teeth had been flossed. Most children had a limited soda, sweet drinks, and fruit juice intake.

CONCLUSIONS

Participants were apparently knowledgeable about prevention, the need to limit sugary beverages, and the importance of brushing twice a day. They were not as knowledgeable about the need for flossing, providing fruits and vegetables to their children, the significance of not skipping a meal, or the appropriate amount of toothpaste use.

Effect of a desensitizing paste containing 8% arginine and calcium carbonate on the surface roughness of dental materials and human dental enamel

PURPOSE

To evaluate the effect of an 8% arginine-calcium carbonate fluoride-free desensitizing paste on the surface roughness of resin composite, porcelain, amalgam, gold, and human dental enamel both prior to and following simulated toothbrushing.

METHODS

A resin composite (Filtek Supreme), a commercial porcelain (IPS Empress), an amalgam (Dispersalloy), gold (JIF-PF) and human dental enamel were used, as well as commercial finishing and polishing instruments. Eight two-sided samples were fabricated for each group. The composite and amalgam samples were stored at 100% relative humidity and 37 degrees C for 48 hours prior to measuring the surface roughness and completing the subsequent finishing and polishing procedures. Enamel blocks were cut from human lesion-free teeth and embedded in acrylic. The blocks were then polished flat with high polishing pastes. For gold and porcelain, the same size was used and the materials processed by a professional dental laboratory. Following storage, each surface was polished using the Super-Snap (Shofu) system. The amalgam was polished with conventional polishing techniques. Roughness (Ra and Ry) was evaluated with both a 3D non-contact profilometer and a stylus profilometer. With the two-sided samples only one side was polished with the desensitizing paste and the other side was left unpolished without paste. The 8% arginine-calcium carbonate desensitizing paste was applied to a surface for 15 seconds using a single disposable prophy cup. Each polished surface was measured by the profilometers and three roughness values per surface were recorded as the "initial prophy" surface. Following initial surface analysis, each side of every sample was treated with a simulated toothbrushing technique using a toothbrushing device (V-8). A 50:50 (w/w) slurry of toothpaste (Colgate Cavity Protection) and deionized water was used. Each surface was brushed 10,000 times. Then, the samples were rinsed with tap water and stored in 100% humidity until roughness values were obtained using the profilometers as previously described ("toothbrush surface"). After analyzing the brushed surfaces, the samples were returned to their original treatment group ("desensitizing paste"). Each surface was re-polished with the desensitizing paste as previously stated. Those surfaces (referred to as "recall paste") were measured as previously described for final surface roughness. Data was analyzed using repeated measures two-factor ANOVA with Tukey HSD pairwise comparison as appropriate (alpha=0.05). Two additional samples were made of each material in order to measure step-heights. Tape was placed on the surface of each sample to separate the treatment side and the non-treated side. The tape was removed before each profilometry reading.

RESULTS

The desensitizing paste containing 8% arginine and calcium carbonate did not have a significant effect on the surface roughness of the substrates tested. Although the 3D non-contact profilometry images showed slight roughness after toothbrushing followed by the use of the desensitizing paste, these changes were not statistically significant (P>0.05).

The effect of a triclosan dentifrice on mucositis in subjects with dental implants: a six-month clinical study

OBJECTIVE

The objective of the present clinical study was to assess the effect of the use of a dentifrice containing triclosan on peri-implant mucositis in subjects that had been restored with dental implants.

METHODS

The trial was designed as a double-blind, randomized, two-treatment, parallel-group clinical study. Sixty male and female subjects, aged 30-70 years, were recruited. All subjects had lost teeth due to periodontal disease, and had been restored with a minimum of two implants at least one year prior to the start of the trial. Subjects were randomly assigned to two treatment groups. The subjects in the test group (Test) brushed their teeth and implant-supported restorations with a dentifrice containing triclosan, while the control subjects brushed with a sodium fluoride dentifrice. Only subjects with a minimum of one implant site showing clinical signs of peri-implant mucositis, i.e., bleeding after probing, were enrolled in the study. Clinical examinations were performed at baseline, and after three and six months. The following parameters were scored: Probing pocket depth (PPD), bleeding on probing (BoP), and plaque. The change from baseline within each treatment group at three months and six months was evaluated for all parameters using ANOVA and ANCOVA.

RESULTS

Subjects with peri-implant mucositis who used a dentifrice containing 0.3% triclosan, as an adjunct to mechanical tooth brushing, exhibited significantly fewer clinical signs of inflammation than subjects who used a regular fluoride dentifrice at six months. The BoP scores were reduced from 53.8% to 29.1% in the Test group, whereas in the same interval there was an increase from 52.3% to 58.8% in the Control group. Furthermore, the individual mean PPD, as well as the frequency of sites with 5 mm and > or = 6 mm deep pockets, were reduced significantly more in the Test than in the Control group.

CONCLUSION

The regular use of a dentifrice containing triclosan may reduce the clinical signs of inflammation in the mucosa adjacent to dental implants.

Clinical stain removal efficacy of two dentifrices after one and two weeks of use

OBJECTIVE

This investigation evaluated extrinsic stain removal efficacy after brushing for one and two weeks with a commercially available fluoride dentifrice relative to Colgate Total Advanced Clean, a new dentifrice formulated with dual-phase silica.

METHODS

At the baseline visit, one-hundred and forty-four adult subjects were stratified by Lobene Stain Index scores and randomized to two treatment groups using either Total Advanced Clean dentifrice (0.3% triclosan, 2% copolymer, dual phase silica) or a commercially available fluoride dentifrice, and instructed to brush twice daily. Tooth stain evaluations were conducted on stain area, stain intensity, and a composite score of both, after one and two weeks of dentifrice use.

RESULTS

Baseline scores demonstrated no significant differences between the two treatment groups for all evaluated stain parameters (p > 0.05). At both the one- and two-week post-use evaluations, subjects brushing with Total Advanced Clean demonstrated significant reductions for all stain parameters versus the control (p < 0.05). The Total Advanced Clean group demonstrated mean reductions in stain intensity of 0.37 and 0.74 at the one- and two-week evaluations, respectively, versus the control group. Corresponding mean reductions in stain area for the Total Advanced Clean group versus the control were 0.12 and 0.24 at the one- and two-week evaluations, respectively. The two post-use evaluations also demonstrated significant reductions in stain composite scores for the subjects assigned Total Advanced Clean (p < 0.0001).

CONCLUSION

In comparison to the control dentifrice, the results demonstrated significantly more stain removal following the use of Total Advanced Clean at each recall visit. Subjects assigned Total Advanced Clean demonstrated continued reductions in stains from baseline to one week, and from one week to two weeks.

A randomized 12-week study to compare the gingivitis and plaque reduction benefits of a rotation-oscillation power toothbrush and a sonic power toothbrush

OBJECTIVE

Sonic and rotation-oscillation power toothbrushes are popular and effective, but have been shown to differ in relative benefits. The objective of this 12-week investigation was to compare the efficacy of a rotation-oscillation powered toothbrush and a newly introduced sonic toothbrush in the reduction of gingivitis and dental plaque.

METHODS

This was a randomized, controlled, examiner-blind, two-treatment, parallel-group study to assess gingivitis reduction and plaque reductions after twice-daily brushing with either the rotation-oscillation brush or the sonic toothbrush over 12 weeks. The Modified Gingival Index (MGI) and Gingival Bleeding Index (GBI) were used to determine gingivitis benefits at Week 6 and Week 12, and plaque was scored at these visits before and after supervised brushing using the Rustogi Modified Navy Plaque Index (RMNPI).

RESULTS

In 171 evaluable subjects, gingivitis reduction benefits were significantly greater for the rotation-oscillation brush group than for those using the sonic toothbrush, with relative mean benefits favoring the rotation-oscillation brush of 29.4% for GBI and 8.2% for MGI at 12 weeks (p < or = 0.01). The rotation-oscillation brush produced significantly lower RMNPI plaque by 33.3% compared to the sonic toothbrush (p < 0.001) at Week 12.

CONCLUSION

The rotation-oscillation power toothbrush was significantly more efficacious than the sonic toothbrush in removing plaque, in reducing gingivitis, and lowering the number of bleeding sites after 12 weeks of twice-daily brushing.

Prevention of lingual calculus formation with daily use of 6% H2O2/2% pyrophosphate whitening strips

OBJECTIVE

This randomized controlled clinical trial was conducted to evaluate whether daily use of a hydrogen peroxide/ pyrophosphate-containing antitartar whitening strip might safely yield clinical reductions in post-prophylaxis calculus accumulation.

METHODS

A three-month, randomized controlled trial was conducted to compare calculus accumulation with a daily 6% hydrogen peroxide/pyrophosphate strip versus regular brushing. After an eight-week run-in phase to identify calculus formers, a prophylaxis was administered, and 77 subjects were randomly assigned to daily strip or brushing only groups. All subjects received an anticavity dentifrice (Crest Cavity Protection) and manual brush for use throughout the three-month study; for subjects assigned to the experimental group, strip application was once daily for five minutes on the facial and lingual surfaces of the mandibular teeth. Efficacy was measured as mm calculus (VMI) before prophylaxis and after six and 12 weeks of treatment, while safety was assessed from examination and interview.

RESULTS

Subjects ranged in age from 21-87 years, with groups balanced (p > 0.26) on pertinent demographic and behavioral parameters, and pre-prophylaxis calculus baseline mean scores (16.0 mm). At Week 6, calculus accumulation was lower in the strip group, with adjusted mean (SE) lingual VMI of 12.0 (0.87) for the strip group and 17.0 (0.88) for the brushing control. At Week 12, calculus accumulation was lower in the strip group, with adjusted mean (SE) lingual VMI of 14.3 (0.85) for the strip group and 17.2 (0.86) for the brushing control. Treatments differed significantly (p < 0.02) on calculus accumulation at both time points. A total of three subjects (8%) in the strip group and two subjects (5%) in the brushing control had mild oral irritation or tooth sensitivity during treatment; no one discontinued early due to an adverse event.

CONCLUSION

Daily use of hydrogen peroxide whitening strips with pyrophosphate reduced calculus formation by up to 29% versus regular brushing, without meaningful adverse events.

Clinical assessment of extrinsic stain removal efficacy with a new Pulsonic toothbrush

OBJECTIVE

To assess the extrinsic stain removal benefit of two different power toothbrushes: an experimental Oral-B Pulsonic rechargeable toothbrush and a positive control Sonicare FlexCare toothbrush.

METHODS

This was a randomized, positive-controlled, examiner-blind, two-treatment, parallel group, two-week study. A Lobene stain index was performed at baseline on the facial surfaces of the anterior teeth. Subjects were randomized to one of two treatment groups: Pulsonic or FlexCare. Both groups were assigned the same fluoride dentifrice, and were instructed to brush their teeth twice per day for two minutes with the assigned toothbrush and dentifrice in front of a mirror. A further Lobene stain index was performed following two weeks of brushing.

RESULTS

A highly significant reduction (p < 0.001) in mean Lobene composite scores after two weeks was found for both the Pulsonic treatment group and the FlexCare treatment group (median reduction of 94.4% and 90.7%, respectively). Both treatment groups also showed a highly significant (p < 0.001) reduction in extent and intensity scores. No significant treatment group differences were seen in the reduction in mean Lobene scores (p > 0.1).

CONCLUSION

Both the experimental Pulsonic and the positive control FlexCare power toothbrushes showed highly effective stain removal efficacy relative to baseline following two weeks of brushing. Stain removal efficacy did not differ significantly between brushes.

Comparison of a dentifrice containing 0.243% sodium fluoride, 0.3% triclosan, and 2.0% copolymer in a silica base, and a dentifrice containing 0.243% sodium fluoride in a silica base: a three-year clinical trial of root caries and dental crowns among adults

OBJECTIVE

Colgate Total toothpaste has been demonstrated to be highly effective in plaque and gingivitis control. The effect of triclosan on root caries and on the survival of dental crowns (fixed dental prosthetic treatment) has not been evaluated. In order to examine these important variables, a randomized controlled clinical trial was conducted comparing Colgate Total toothpaste with triclosan, and an identical fluoride toothpaste without triclosan.

METHODS

Adult subjects were randomly assigned to a test group using Colgate Total plus Whitening toothpaste with triclosan, and a control group using Colgate sodium fluoride toothpaste without triclosan. By the end of the study, following three years of product use, an evaluation was performed to compare baseline data to the three-year data for root caries and dental crown survival. Clinical root caries was evaluated by the Katz RCI- Root Caries Index. Within-treatment analysis for each dentifrice was conducted using a paired t-test. Between-treatment analysis was performed using Analysis of Covariance (ANCOVA). For fixed dental prosthetic treatment evaluation, dental crowns were dichotomized for success and failure at the end of the study. Within-treatment analysis for each dentifrice was conducted using a paired t-test. Between-treatment analysis was performed using the Bonferroni test.

RESULTS

One-thousand, three-hundred, and fifty-seven subjects (1,357) completed the study. Regarding root caries, at termination of the study the Colgate Total group presented a mean score of 1.14 +/- 1.75 and a +5.6% change from baseline, while the sodium fluoride toothpaste presented a mean of 1.25 +/- 1.88 and a +43.2% change from baseline (p < 0.001). The adjusted mean root caries increment was 0.07 +/- 0.03 for the Colgate Total group, and 0.38 +/- 0.03 for the sodium fluoride toothpaste group (p < 0.001). Regarding crowns, at termination of the study the Colgate Total group presented a mean score of 5.38 +/- 3.70 and a +1.1% change from baseline, while the sodium fluoride toothpaste without triclosan presented a mean of 5.75 +/- 3.86 and a +3.8% change from baseline (p < 0.001). The mean (adjusted for multiple comparisons) dental crowns failure increment was 0.09 +/- 0.03 for the Colgate Total group, and 0.31 +/- 0.02 for the sodium fluoride toothpaste group (p < 0.001).

CONCLUSION

A comparison between the two study groups revealed a statistically significant difference for root caries and dental crown failure scores, both favoring the triclosan toothpaste (Colgate Total). The significantly lower root caries and observed dental crown failure scores among the Colgate Total toothpaste users indicate an effect of the triclosan and the copolymer system. These results are important and could provide a strong and valuable public health measure.

Efficacy of three toothbrushes on established gingivitis and plaque

PURPOSE

To evaluate the efficacy of three toothbrushes [Colgate 3600 Deep Clean (AFT version), the Colgate 3600 Deep Clean (stapled version) and the Oral B Indicator] on the removal of established gingivitis and plaque.

METHODS

This examiner-blind, three-treatment, parallel clinical research study assessed plaque removal via the comparison of pre-to- post-brushing and 4-week plaque removal measured by the Rustogi Modification of the Modified Navy Plaque Index. This study also assessed gingivitis using the Löe & Silness Gingival Index. Qualifying adult male and female subjects from the Northern New Jersey area reported to the study site after refraining from any oral hygiene procedures for 12 hours; and from eating, drinking, or smoking for 4 hours. Following an examination for gingivitis and plaque (pre-brushing), they were randomized into three balanced groups, each group using one of the three study toothbrushes in the order specified by a pre-determined randomization plan. Subjects were instructed to brush their teeth for 1 minute under supervision with their assigned toothbrush and a commercially-available toothpaste (Colgate Cavity Protection), after which they were once again evaluated for plaque (post-brushing). Subjects were then dismissed from the study site with the toothpaste and their assigned toothbrush to use at home twice daily for the next 4 weeks. They again reported to the study site at which time they were evaluated for plaque and gingivitis.

RESULTS

109 subjects complied with the protocol and completed the clinical study. For plaque removal, comparisons were made for whole mouth, at the gingival margin and at interproximal sites. The results of the study indicated that all three test toothbrushes provided statistically significantly reductions in pre- to post-brushing plaque index scores of up to 44.0%, 38.6% and 23.6% respectively, after a single toothbrushing. Relative to the Oral B Indicator toothbrush, the Colgate 360 degree Deep Clean toothbrush (AFT version) and Colgate 360 degrees Deep Clean toothbrush (stapled version) provided a statistically significantly greater removal of plaque of up to 107% and 93.0%, respectively, after a single toothbrushing. Also, the group using the Colgate 360 degree Deep Clean toothbrush (AFT version) and the Colgate 360 degree Deep Clean toothbrush (stapled version) exhibited a statistically significantly greater removal of plaque of up to 575% and 400%, respectively, when compared to the Oral B Indicator toothbrush after 4 weeks. The group using the Colgate 3600 Deep Clean toothbrush (AFT version) and the Colgate 3600 Deep Clean toothbrush (stapled version) exhibited statistically significantly greater reductions in gingivitis of up to 23% and 17%, respectively, and greater reductions in gingivitis severity (bleeding sites) of up to 73% and 52% respectively, as compared to the Oral B Indicator toothbrush after 4 weeks. There was no statistically significant difference between the two Colgate 3600 toothbrushes for any parameter and at any comparison time.

Effect of an oscillating rotating power toothbrush on plaque removal and regrowth

PURPOSE

To measure the effectiveness of an oscillating rotating power toothbrush as compared to a manual toothbrush.

METHODS

17 subjects were preliminarily assigned commercial tubes of Crest Cavity Protection (CCP) dentifrice and an Oral-B manual toothbrush (P35) with instructions for bid brushing morning and evening. Subjects remained on CCP dentifrice for 2 weeks during which they were imaged on 6 days (three each week) including daily assessments of morning plaque levels before brushing (AM), morning plaque levels after brushing (PB) and afternoon plaque levels allowing for regrowth (PM). Plaque was evaluated using standardized UV imaging techniques [Digital Plaque Image Analysis (DPIA) methodology]. At Week 3, subjects replaced their manual brush with an oscillating rotating power toothbrush (Oral-B Triumph) and were supplied with a detailed instruction/training video to assist in education and compliance with the power brush regimen. Plaque was evaluated during Week 3 on three additional days with measures again including AM, PB and PM. Throughout, plaque results are reported as average plaque area coverage on dentition.

RESULTS

AM: Manual (2 week avg. +/- SD): 18.7 +/- 8.8; Power = 10.3 +/- 3.3 (44.9% relative reduction P < 0.05); PB: Manual (2 week avg.): 8.5 +/- 4.2; Power 4.6 +/- 1.9 (45.9% relative reduction P < 0.05); PM: Manual (2 week avg.): 14.9 +/- 6.4; Power = 8.2 +/- 3.1 (45.0% relative reduction P < 0.05).

In vivo antiplaque efficacy of combined antimicrobial dentifrice and rinse hygiene regimens

PURPOSE

To evaluate using digital plaque image analysis the antiplaque efficacy of oral care regimens including use of antimicrobial toothpaste in combination with antimicrobial mouthrinse.

METHODS

16 subjects completed the study protocol including: (1) initial treatment phase, all subjects used a standard sodium fluoride dentifrice with 2x/day brushing, (2) second treatment phase, subjects were randomized to two treatment groups: stannous fluoride/sodium hexametaphosphate dentifrice or sodium fluoride triclosan/copolymer dentifrice; (3) third treatment phase, the group using stannous fluoride dentifrice rinsed with alcohol-free cetylpyridinium chloride mouthrinse and the group using triclosan dentifrice rinsed with essential oil mouthrinse. During each phase, plaque levels were assessed in the morning before toothbrushing (AM), post-brushing in the morning (PB) and in the afternoon (PM).

RESULTS

Stannous fluoride dentifrice was superior to triclosan dentifrice in plaque growth inhibition between toothbrushing. Both mouthrinses provided additional plaque prevention benefits when used with antimicrobial dentifrices. The cetylpyridinium chloride mouthrinse and stannous fluoride dentifrice regimen was particularly effective, building accretive efficacy over time. Average plaque reductions exceeded 50% vs. sodium fluoride dentifrice alone. Chemotherapeutic dentifrices and rinses increase plaque control used alone and particularly in combination. The stannous fluoride-cetylpyridinium chloride regimen showed the greatest benefits.

Clinical evaluation of the effects of a sonic toothbrush with ultrasound waveguide in disrupting plaque with and without bristle contact

PURPOSE

To assess the in vivo plaque removal efficacy of the newly marketed sonic/ultrasonic toothbrush. Plaque removal resulting from the toothbrush being held approximately 3 mm from the tooth surface was compared versus a no brushing control. Also, plaque removal resulting from the brush being used according to the manufacturer's instructions was compared versus a control of using the brush (with power turned off) like a manual toothbrush would be used.

METHODS

This was a replicate use, four-treatment, examiner-blind, randomized, eight-period crossover design single brushing plaque study involving 31 subjects. The four treatment regimens consisted of (1) brushing for 2 minutes with the Ultreo powered toothbrush according to manufacturer's instructions, (2) brushing for 2 minutes with the Ultreo toothbrush (power turned off) using the brush like a manual toothbrush, (3) having a trained dental hygienist hold the Ultreo toothbrush head 3 mm from tooth surfaces for a total of 2 minutes, or (4) swishing with a dentifrice slurry for 1 minute in the absence of toothbrushing. For each subject, an experienced, calibrated plaque examiner performed the Turesky Modified Quigley-Hein Plaque Index prior to brushing and following brushing. The difference (baseline minus post-regimen) in average scores was calculated for each subject. The difference scores were analyzed for treatment regimen differences using a mixed model ANCOVA (with baseline whole-mouth average score as the covariate and subjects considered random) for a crossover design.

RESULTS

Adjusted mean plaque removal scores (baseline plaque score minus post-brushing plaque score) were 0.052 for swishing with a dentifrice slurry, 0.058 for the dental hygienist holding the Ultreo toothbrush approximately 3 mm from tooth surfaces, 0.536 for the Ultreo toothbrush used according to manufacturer's instructions and 0.666 for the Ultreo toothbrush (power turned off) used like a manual toothbrush. The difference between the Ultreo toothbrush held approximately 3 mm from tooth surfaces and swishing with a dentifrice slurry was not statistically significant (P = 0.808). The adjusted mean plaque removal score for the Ultreo toothbrush (power turned off) used like a manual toothbrush was statistically significantly (P < 0.001) greater than the corresponding score for the Ultreo toothbrush used per manufacturer's instructions. Ultreo used like a manual toothbrush had an adjusted mean plaque removal score that was 12.4% greater than that for Ultreo used per manufacturer's instructions. Finally, plaque removal scores for the Ultreo toothbrush used per manufacturer's instructions and used like a manual toothbrush were statistically significantly (P < 0.001) greater than plaque removal scores for the non-brushing treatment regimens.

[Use of silicon as inductor of the resistance in potato to Myzus persicae (Sulzer) (Hemiptera: Aphididae)]

The aphid Myzus persicae (Sulzer) is an important pest of potato and causes direct harm, due to the quantity of sap extracted and for being vector of important phytovirus. This work was carried out to evaluate the action of silicon as a resistance inducer of potato to M. persicae. Four treatments were tried: foliar fertilization with silicon acid at 1%; soil fertilization with 250 ml silicic acid solution at 1%; foliar fertilization with silicon acid at 1% + soil fertilization with 250 ml silicic acid solution at 1%; and a control. The treatments were applied thirty days after the explants emergence. Fifteen days after the application of the treatments, feeding preference and some biological aspects of the aphids were evaluated. After, the content of tannins and lignin present in the leaves and the activity of the enzymes peroxidase and phenylalanine ammonia-lyase were also determined. The silicon fertilization did not affect the preference of the aphids; however it reduced fecundity and the rate of population growth of the insects. The lignin percentage increased in the leaves of plants fertilized with silicon via soil and/or foliar and the percentage of tannins increased only in the leaves fertilized via soil plus foliar. The silicon acted as a resistance inducer to M. persicae in potato.

Clinical studies to assess the extrinsic stain prevention and stain removal efficacy of a variant of a commercially available dentifrice containing a new dual silica system

OBJECTIVE

The objective of these two six-week, double-blind clinical studies was to compare the extrinsic stain prevention (Study #1) and stain removal (Study #2) efficacy of a new dentifrice (Colgate Total Advanced Toothpaste) containing 0.3% triclosan/ 2.0% polyvinylmethyl ether/maleic acid (PVM/MA) copolymer/0.243% sodium fluoride in a 17% dual silica base, to a commercially available fluoride dentifrice without tooth whitening ingredients (Crest Cavity Protection Toothpaste) containing 0.243% sodium fluoride in a silica base.

METHODS

Following baseline examinations for extrinsic tooth stain and an oral tissue examination, qualifying adult male and female subjects from the northern and central New Jersey, USA areas were randomized for each study into two treatment groups which were balanced for gender and level of extrinsic tooth stain. Subjects received a full oral prophylaxis at the start of Study #1 only. All subjects were provided with their assigned product and a soft-bristled adult toothbrush for home use. Subjects were instructed to brush their teeth for one minute twice daily (morning and evening) using only the dentifrice and toothbrush provided, and to refrain from using any other oral hygiene products for the entire six weeks of the study. There were no restrictions regarding diet or smoking habits during the course of the study. Examinations for extrinsic tooth stain and oral tissue assessments were repeated after three weeks and six weeks of product use.

RESULTS

One-hundred fourteen (114) subjects participating in Study #1 and 119 subjects participating in Study #2 complied with the protocol and completed the entire study. In both studies, at the three-week and the six-week examinations, subjects who used the new dentifrice exhibited statistically significantly lower levels of extrinsic tooth stain area and extrinsic tooth stain intensity than did those subjects who used the commercially available fluoride control dentifrice.

CONCLUSION

A new dentifrice containing 0.3% triclosan/2.0% PVM/MA copolymer/0.243% sodium fluoride in a 17% dual silica base is more efficacious in the prevention and removal of extrinsic tooth stain than a commercially marketed fluoride dentifrice.

Enhancement of plaque removal efficacy by tooth brushing with baking soda dentifrices: results of five clinical studies

OBJECTIVE

An earlier clinical study demonstrated that brushing with a commercial Arm & Hammer dentifrice containing baking soda physically removed significantly more plaque than brushing with either of two commercial dentifrices which did not contain baking soda. However, little has been done to confirm these results and to compare baking soda-containing dentifrices with more recently commercialized non-baking soda dentifrice formulations. The objective of this study was to compare commercial dentifrices containing 20% to 65% baking soda and commercial dentifrices without baking soda in enhancing plaque removal efficacy of tooth brushing.

METHODS

Five randomized, controlled, blinded, crossover clinical studies were performed among healthy adult volunteers who provided informed consent. After approximately 24 hours without oral hygiene, subjects with sufficient plaque were enrolled in the study phase. Plaque was scored before and after supervised brushing for one minute using the Turesky, et al. modification of the Quigley-Hein Plaque Index at six sites per tooth according to Soparkar's modification as described by Lobene, et al. In each study, wash-out periods with a regular dentifrice not evaluated in the study separated each product treatment.

RESULTS

In all studies, every dentifrice exhibited a significant (p < 0.0001) reduction in 24-hour plaque scores. Between-group comparisons of whole mouth plaque scores in all five studies demonstrated that brushing with baking soda dentifrices resulted in statistically greater (p < 0.01) reductions in whole mouth mean plaque scores than brushing with dentifrices that did not contain baking soda. Results on other tooth surfaces, such as facial, lingual, proximal, and gingival surfaces also demonstrated statistically greater (p < 0.05) reductions in mean plaque scores for the baking soda-containing dentifrices as compared to the baking soda-free dentifrices. In three of the studies comparing different levels of baking soda, brushing with dentifrices with higher concentrations of baking soda consistently removed numerically more plaque than those containing lower levels. In one of these three studies, the difference in plaque removal between the baking soda dentifrices reached statistical significance. The results suggest a positive relationship between plaque removal efficiency and baking soda concentration.

CONCLUSION

The collective results from the five controlled clinical studies on over 270 subjects reported in this paper, consistently demonstrate that Arm & Hammer baking soda dentifrices enhanced plaque removal effectiveness of tooth brushing to a significantly greater extent than the non-baking soda dentifrice products.

The Modified Gingival Margin Plaque Index: a predictable clinical method

OBJECTIVE

This investigation was designed to determine whether the Modified Gingival Margin Plaque Index (MGMPI) method could consistently detect a significant statistical difference between two control commercial products for antiplaque efficacy.

METHODS

The data from 28 studies, where the MGMPI was used on Colgate Total, a well-documented, antiplaque dentifrice versus Colgate Cavity Protection, a regular fluoride dentifrice, were analyzed. The differences between the baseline and a 24-hour plaque scoring were used.

RESULTS

The analysis demonstrated that the delta score from baseline to the 24-hour scoring was consistently lower for the Colgate Total dentifrice. This difference was statistically significant in 23 of the 28 studies, yielding an 82% probability of success rate. The subject numbers in the studies ranged from 9 to 19, and impacted the statistical findings.

CONCLUSION

The power of a study to detect significant statistical differences is dependent upon the number of subjects in the study or the data sample size. The MGMPI was found to give consistent and predictable data for clinical trials, with the additional benefit of convenience for the examiner and for the subjects.

The effect of anti-sensitivity dentifrices on brushing abrasion of eroded dentin in vitro

OBJECTIVE

To investigate the abrasive effects of three marketed anti-sensitivity, and one marketed regular dentifrice on dentin, using an erosion-abrasion in vitro model.

METHODS

Standardized human dentin specimens were prepared and exposed to cycles of erosion, remineralization, and tooth brushing, utilizing the four commercially available dentifrices. Dentin surface loss was then measured by optical profilometry after a total of nine complete cycles. The RDA and pH values of the dentifrices were also measured to assist in the interpretation of results.

RESULTS

Profilometry showed significantly greater dentin surface loss for both Colgate Sensitive Fresh Stripe and Colgate Sensitive Multi Protection when compared with Sensodyne Total Protection or Crest Cavity Protection dentifrices. The abrasive level of dentifrices correlated positively (r-squared = 0.66; p < 0.05) with dentin surface loss.

CONCLUSION

This study demonstrated that the abrasivity of dentifrices can have a significant effect on the wear of eroded dentin in vitro.

A clinical investigation of the efficacy of two dentifrices for the reduction of supragingival calculus formation

OBJECTIVE

The objective of this double-blind clinical study, conducted in harmony with Volpe-Manhold design for studies of dental calculus, was to compare the efficacy of a dentifrice containing 0.3% triclosan/2.0% polyvinylmethyl ether/maleic acid (PVM/MA) copolymer/0.243% sodium fluoride in a 17% dual silica base (Colgate Total Advanced Toothpaste) to that of a commercially available dentifrice containing 0.243% sodium fluoride in a silica base (Crest Cavity Protection Toothpaste) with respect to the reduction of supragingival calculus formation.

METHODS

Adult male and female subjects from the San Francisco area were entered into the eight-week pre-test phase of the study. Subjects received an evaluation of oral soft and hard tissues and were given a complete oral prophylaxis. They were provided with a non-tartar control placebo dentifrice and a soft-bristled adult toothbrush, and were instructed to brush their teeth twice daily (morning and evening) for one minute. After eight weeks of using the placebo dentifrice, subjects were examined for baseline supragingival calculus formation using the Volpe-Manhold Calculus Index. Qualifying subjects were randomized into two treatment groups which were balanced for gender and baseline calculus scores. All subjects entered into the twelve-week test phase were given a complete oral prophylaxis, and were provided with their assigned dentifrice and a soft-bristled adult toothbrush for home use. Subjects were instructed to brush their teeth for one minute twice daily (in the morning and evening). Prior to each study visit, subjects refrained from brushing their teeth and eating and drinking for four hours.

RESULTS

Seventy-seven (77) subjects complied with the protocol and completed the study. At the twelve-week examination, the Test Dentifrice group presented a mean Volpe-Manhold Calculus Index score of 13.22 and the Control Dentifrice group presented a score of 20.29. After twelve weeks of product use, the Test Dentifrice group exhibited 34.8% less supragingival calculus formation than the Control Dentifrice group (statistically significant at p < 0.05).

CONCLUSION

The overall results of this double-blind clinical study support the conclusion that after twelve weeks' use of a dentifrice containing 0.3% triclosan/2.0% PVM/MA copolymer/0.243% sodium fluoride in a 17% dual silica base provides significantly greater control of supragingival calculus formation relative to that of a commercially available dentifrice containing 0.243% sodium fluoride in a silica base.

A four-week clinical study to evaluate and compare the effectiveness of a baking soda dentifrice and an antimicrobial dentifrice in reducing plaque

OBJECTIVE

To evaluate and compare the effectiveness in reducing plaque of a fluoride dentifrice containing baking soda and a non-baking soda fluoride dentifrice containing an antimicrobial (triclosan/copolymer) system after a single brushing and over a four-week period of daily brushing.

METHODS

A total of 207 subjects completed this randomized, blinded, parallel-group clinical study. Twenty-four hour plaque buildup was scored at baseline and after two and four weeks of twice-daily use of the products. Additionally, controlled single brushing with the assigned dentifrice, followed by post-brushing plaque assessment, was performed at the start (baseline visit) and end (Week-4 visit) of the study. Plaque was scored using the Turesky, et al. modification of Quigley-Hein Index at six sites per tooth, according to Soparkar's modification.

RESULTS

Mean baseline whole mouth plaque scores for the baking soda and triclosan dentifrice groups were 2.90 +/- 0.40 and 2.90 +/- 0.39, respectively, and the difference was not statistically significant. Within-group analysis showed that both products significantly reduced the amount of plaque over the four-week period (p < 0.001). Between-group analysis showed that brushing with the baking soda dentifrice exhibited significantly greater reduction in plaque scores (p < 0.001) after two and four weeks of brushing as compared to the triclosan dentifrice. After four weeks, the mean plaque reduction for the baking soda dentifrice group (0.34 +/- 0.32) was 2.22-fold greater than that observed for the triclosan dentifrice group (0.15 +/- 0.24). Similarly, single brushing with the baking soda dentifrice showed a 1.88- to 2.08-fold greater pre- to post-brushing plaque difference as compared to the triclosan dentifrice at the baseline visit (mean plaque reduction: baking soda 0.54 +/- 0.26; triclosan 0.28 +/- 0.18; ratio 1.88X) and Week-4 visit (baking soda 0.47 +/- 0.21; triclosan 0.23 +/- 0.15; ratio 2.08X). Similar to the whole mouth scores, evaluation of various tooth sites (facial, lingual, proximal, and gingival) showed a significantly greater reduction in plaque scores for brushing with the baking soda dentifrice as compared to brushing with the triclosan dentifrice.

CONCLUSION

The results of this study indicate that the baking soda dentifrice was more effective than the non-baking soda, antimicrobial dentifrice in plaque removal after a single tooth brushing, and in maintaining significantly lower plaque levels during a four-week period of twice daily, unsupervised tooth brushing.

Dental plaque control effect of a zinc citrate dentifrice

OBJECTIVE

This research evaluated the antiplaque efficacy of a new 2% zinc citrate fluoride dentifrice versus a non-zinc matching placebo or a commercial fluoride dentifrice, also used as the washout product in two crossover studies.

METHODS

Healthy human subjects meeting inclusion criteria entered two respective randomized crossover clinical studies. Study 1 had 24 subjects, and compared the zinc dentifrice to the commercial fluoride dentifrice over a 24-hour period. Study 2 had 19 subjects, and compared the zinc dentifrice to the matching placebo over a 24-hour period. After one week of washout using the commercial fluoride dentifrice, the subjects used the test product for one week prior to the test period. Both studies employed the Modified Gingival Margin Plaque Index (MGMPI) for the assessments.

RESULTS

In Study 1, the mean differences in the MGMPI score, representing post-treatment plaque regrowth along the gingival margin for the zinc prototype as compared to the commercial fluoride dentifrice, were 13.87 (+/- 8.27) and 21.23 (+/- 11.08), respectively. Study 2 demonstrated the mean differences in MGMPI scores for the zinc dentifrice and a matching placebo of 14.99 (+/- 13.32) and 24.38 (+/- 7.69), respectively. In both studies, the zinc dentifrice demonstrated a significant 35% and 39% inhibition of dental plaque formation compared to those of their respective control dentifrices.

CONCLUSION

Two clinical studies demonstrated plaque control efficacy for a new zinc citrate-containing dentifrice, suggesting a new antiplaque and possible multi-benefit dentifrice for oral hygiene.

A clinical investigation of the efficacy of two dentifrices for controlling established supragingival plaque and gingivitis

OBJECTIVE

To assess the efficacy of a dentifrice containing 0.3% triclosan/2.0% polyvinylmethyl ether/maleic acid (PVM/MA) copolymer/0.243% sodium fluoride in a 17% dual silica base (Colgate Total Advanced Toothpaste-Test Dentifrice) for controlling established supragingival plaque and gingivitis, relative to that of a commercially available dentifrice containing 0.243% sodium fluoride in a silica base (Crest Cavity Protection Toothpaste-Control Dentifrice).

METHODS

Following a baseline examination for supragingival plaque and gingivitis, qualifying adult male and female subjects from the Barcelona, Spain area were randomized into two treatment groups. Subjects were given a complete oral prophylaxis and instructed to brush their teeth twice daily (morning and evening) for one minute with their assigned dentifrice and a soft-bristled toothbrush. Examinations for supragingival plaque and gingivitis were repeated after three months and six months of product use.

RESULTS

Ninety-four (94) subjects complied with the protocol and completed the study. Relative to the Control Dentifrice group, the Test Dentifrice group presented statistically significantly lower whole-mouth plaque index and gingival index scores (18.6% and 15.8%, respectively) after three months of product use. Similarly, relative to the Control Dentifrice group, the Test Dentifrice group exhibited statistically significant reductions in plaque index and gingival index scores measured on proximal sites (17.0% and 16.3%,respectively), and statistically significant reductions in plaque severity index and gingivitis severity index scores (22.2% and 46.9%, respectively) after three months of product use. Relative to the Control Dentifrice group, the Test Dentifrice group presented statistically significantly lower whole-mouth plaque index and gingival index scores (23.4% and 21.3%, respectively) after six months of product use. Similarly, relative to the Control Dentifrice group, the Test Dentifrice group exhibited statistically significant reductions in plaque index and gingival index scores measured on proximal sites (21.1% and 23.0%, respectively), and statistically significant reductions in plaque severity index and gingival severity index scores (27.1% and 64.5%, respectively) after six months of product use.

CONCLUSION

The overall results of this double-blind clinical study, conducted in accordance with the quantitative criteria established by the American Dental Association, support the conclusion that a dentifrice containing 0.3% triclosan/2.0% PVM/MA copolymer/0.243% sodium fluoride in a 17% dual silica base is efficacious for the control of established supragingival plaque and gingivitis.

Clinical investigation of the antiplaque efficacy of a new variant of a commercially available triclosan/copolymer/fluoride dentifrice

OBJECTIVE

The objective of two single-blind, three-treatment, crossover design, clinical studies was to evaluate the antiplaque efficacy using the Modified Gingival Margin Plaque Index (MGMPI) scores of three dentifrices: 1) a dentifrice containing 0.3% triclosan/2.0% polyvinylmethyl ether/maleic acid (PVM/MA) copolymer/sodium fluoride in a 17% dual silica base (Colgate Total Advanced Toothpaste-Test Dentifrice); 2) a commercially available dentifrice containing 0.3% triclosan/2.0% PVM/MA copolymer/sodium fluoride in a 10% high-cleaning silica base (Colgate Total Toothpaste-Positive Control Dentifrice); and 3) a commercially available dentifrice containing 0.243% sodium fluoride in a regular silica base (Colgate Winterfresh Gel-Negative Control Dentifrice).

METHODS

In each study, subjects reported to the clinical facility, and those who met the inclusion/exclusion criteria were given a complete oral prophylaxis, a soft-bristled toothbrush, and a commercially available dentifrice (Colgate Cavity Protection Fluoride Toothpaste). They were instructed to use these products exclusively for seven days (washout period), after which time they reported back to the clinical facility and were randomized into three treatment groups. All subjects then brushed their teeth for one minute with a full ribbon (approximately 1.5 gm) of Colgate Cavity Protection Fluoride Toothpaste, and immediately followed with a one-minute brushing using a full ribbon of one of the three study dentifrices. Subjects then rinsed with a red disclosing solution (Butler Red-Cote) and had their teeth and gums examined to assess their plaque content. They returned to the clinical facility after 24 hours of no oral hygiene to again have their teeth and gums examined to assess their plaque content. As per the crossover clinical design, the same methods and materials were used until all subjects used all three study treatments.

RESULTS

Seventeen subjects in the first study and 16 subjects in the second study complied with the protocol and completed all phases of the study. Two-way ANOVA results from both studies showed that there was no difference in mean delta MGMPI scores between the groups using the Test Dentifrice and the Positive Control Dentifrice. Results also showed that there was a statistically significant difference (p < 0.05) in delta MGMPI scores between both the Test Dentifrice treatment and the Positive Control Dentifrice treatment when compared to the Negative Control Dentifrice.

CONCLUSION

A new improved dentifrice containing 0.2% triclosan/3.0% PVM/MA copolymer/sodium fluoride in a 17% dual silica base is comparable in controlling dental plaque when compared to a Positive Control Dentifrice containing 0.3% triclosan/2.0% PVM/MA copolymer/sodium fluoride in a 10% high-cleaning silica base, and is statistically significantly better in controlling dental plaque when compared to a Negative Control Dentifrice containing 0.243% sodium fluoride in a silica base.

A clinical investigation of the efficacy of two dentifrices for controlling oral malodor and plaque microflora overnight

OBJECTIVE

The objective of this independent, double-blind, overnight clinical study was to assess the efficacy of a dentifrice containing 0.3% triclosan/2.0% polyvinylmethyl ether/maleic acid (PVM/MA) copolymer/0.243% sodium fluoride in a 17% dual silica base (Colgate Total Advanced Toothpaste) for the overnight control of oral malodor and plaque microflora, relative to that of a commercially available dentifrice containing 0.243% sodium fluoride in a silica base (Crest Cavity Protection Toothpaste).

METHODS

After a five-day period using a supplied commercially available fluoride toothpaste, adult male and female subjects from the Chengdu, China area reported to the clinical facility in the evening, after having refrained from the use of all oral hygiene procedures, as well as eating and drinking, for at least six hours. Following an assessment of the oral soft and hard tissues, subjects were evaluated for baseline oral malodor by a panel of four trained judges using a nine-point hedonic scale. Plaque samples (baseline) from the teeth on the left side of subjects' mouths were also collected. Subjects who presented a mean baseline oral malodor score between 6.0 and 8.4 were stratified according to their oral malodor score and randomly assigned within strata to one of the two treatment groups. Subjects were provided with their assigned dentifrice and instructed to brush their teeth on the left side of their mouth only, for one minute under supervision. Subjects returned to the testing facility the following morning for an overnight evaluation, having refrained from the use of all oral hygiene procedures, and from eating and drinking. An oral malodor assessment was performed, plaque samples were collected from the teeth on the right side of the mouth, and a final oral soft and hard tissue evaluation was performed.

RESULTS

Eighty-one (81) subjects completed the study. At the overnight evaluation, subjects in the triclosan/copolymer/fluoride dentifrice group and the fluoride dentifrice group presented mean oral malodor scores of 4.91 and 6.86, respectively. Relative to the fluoride dentifrice group, at the overnight evaluation the triclosan/copolymer/fluoride dentifrice group presented a statistically significant 28.4% reduction in oral malodor scores. Additionally, at the overnight evaluation, subjects in the triclosan/ copolymer/fluoride dentifrice group and the fluoride dentifrice group presented geometric mean microbial colony forming unit (CFU) scores of 3.15 and 6.07, respectively. Relative to the fluoride dentifrice group, at the overnight evaluation the triclosan/copolymer/ fluoride dentifrice group presented a statistically significant 49.5% reduction in microbial CFU scores.

CONCLUSION

The overall results of this double-blind clinical study support the conclusion that a single evening's use of a dentifrice containing 0.3% triclosan/2.0% PVM/MA copolymer/0.243% sodium fluoride in a 17% dual silica base provides statistically significantly lower levels of overnight (12-hour) oral malodor and plaque microflora when compared to a commercially available dentifrice containing 0.243% sodium fluoride in a silica base.

Tooth whitening through the removal of extrinsic stain with two sodium hexametaphosphate-containing whitening dentifrices

PURPOSE

To evaluate the tooth whitening benefit through stain removal delivered by a marketed whitening dentifrice (Crest Vivid White) used twice a day or a combination regimen of two marketed dentifrices (Crest Vivid White Night used at night and Crest Cavity Protection used in the morning) relative to a positive control over a 2-week period.

METHODS

Both studies were randomized, two treatment, parallel group, examiner-blind, 2-week clinical trials involving 22 and 30 healthy adults with longstanding visible extrinsic stain on the facial surfaces of at least six anterior teeth. In each study, subjects were randomized to one of two treatments: a sodium fluoride/sodium hexametaphosphate whitening dentifrice used alone (Study 1) or in combination with a cavity protection dentifrice (Study 2) with an ADA reference manual toothbrush versus a control power toothbrush with a cavity protection dentifrice (both studies).

RESULTS

In both studies, all treatment groups statistically significantly (P < 0.001) reduced baseline stain scores following 1 and 2 weeks of brushing. After 2 weeks, the whitening dentifrice used twice daily had a median percent stain removal of 90% and the night-time whitening dentifrice (used once a day) in combination with the cavity protection dentifrice had a median percent stain removal of 85% while powered toothbrush groups showed median percent stain removal of 88-89% in both studies. Stain removal scores after 1 and 2 weeks of brushing did not differ significantly between the two treatment groups in either study.