Antibacterial Action of a Condensed Tannin Extracted from Astringent Persimmon as a Component of Food Addictive Pancil PS-M on Oral Polymicrobial Biofilms.

The purpose of this study was to evaluate the antibacterial activity against polymicrobial (PM) biofilms of a condensed tannin extracted from astringent persimmon (PS-M), which is contained in refreshing beverages commercially available in Japan. Salivary PM biofilms were formed anaerobically on glass coverslips for 24 and 72 h and were treated for 5 min with sterilized deionized water (DW), 0.05 and 0.2 wt% chlorhexidine digluconate (CHX), and 0.5-4.0 wt% PS-M solution. The colony forming units (CFU/mL) were determined and morphological changes of the biofilms were observed by scanning electron microscopy (SEM). The CFUs were lower in all PS-M and CHX groups compared to the DW group. PS-M exerted a dose-dependent effect. PS-M (1.53 × 10(7)) at a dose of 4.0 wt% had the same effect as 0.2 wt% CHX (2.03 × 10(7)), regardless of the culture period. SEM revealed the biofilm structures were considerably destroyed in the 4.0 wt% PS-M and 0.2 wt% CHX. These findings indicate that the antibacterial effects of PS-M, a naturally derived substance, are comparable to those of CHX. PS-M may keep the oral cavity clean and prevent dental caries and periodontal disease related to dental plaque, as well as systemic disease such as aspiration pneumonitis.

Effects of resin-based temporary filling materials against dentin demineralization.

This study investigated the in vitro anti-demineralization effects of resin-based temporary filling materials containing surface prereacted glass-ionomer (S-PRG) filler on dentin. Bovine root dentin specimens with a 3×3 mm experimental surface were divided into four treatment groups: DuraSeal (DU) as a control, S-PRG filler-free temporary material (S0), material containing 10% (S10) and 20% (S20) S-PRG filler. Each material was applied to 3×2 mm of the experimental surface, and the specimens were immersed in 8% methylcellulose gel demineralization system for one week at 37˚C. Mineral profiles and integrated mineral loss (IML) of lesions induced on the surface (3×1 mm) adjacent to the materials were computed by transversal microradiography. S10 and S20 yielded thick surface layers and shallow lesion bodies, with significantly lower IML than DU and S0 (p<0.05, Tukey's test). These findings indicate that temporary filling resin-based materials containing over 10% of S-PRG filler content have anti-demineralization effects on adjacent dentin.

Formation of subsurface dentin lesions using a polymicrobial biofilm model.

PURPOSE: To simulate an oral demineralization environment by multiple species of bacteria by inducing subsurface dentin lesions with a polymicrobial biofilm model. METHODS: Polymicrobial biofilms consisting of multiple species of bacteria were generated from stimulated saliva using a high-throughput active attachment model. Biofilms were grown on dentin specimens in McBain medium containing 0, 0.2 or 2.5 ppm F and on glass without fluoride for 192 hours. The medium was refreshed twice daily, after 10 and 14 hours, until 72 hours, followed by treatment for 5 minutes with 400 ppm fluoride. Specimens were recovered after 192 hours. The number of colony forming units (CFU) was measured, and integrated mineral loss (IML) was determined by transversal microradiography. RESULTS: Mineral profiles in specimens grown with 0.2F and 2.5F revealed surface layers and initial lesions distinct from those grown with 0F. IML was significantly lower with 0.2F and 2.5F than with 0F (P < 0.05), although CFUs were similar. CFUs of biofilms grown on dentin in medium containing 0F were 10-fold higher than on glass (P < 0.05). Subsurface lesions on dentin formed consistently, with their growth progression inhibited by application of fluoride. To our knowledge, this is the first report describing the induction of subsurface dentin lesions by a polymicrobial biofilm model, and this model may be useful for studies of demineralization supporting in situ and in vivo models.

Chemical alteration by tooth bleaching of human salivary proteins that infiltrated subsurface enamel lesions--experimental study with bovine lesion model systems.

Salivary macromolecules infiltrate white and brown spot enamel lesions and adsorb onto hydroxyapatite. Calcium-binding salivary proteins such as statherin hinder remineralization of these lesions. We assessed whether bleaching agents can remove salivary components that have infiltrated and bound to experimental subsurface lesions in bovine enamel prepared by immersing specimens in acid and then human saliva. Transversal microradiography showed that such demineralized lesions mimicked incipient carious lesions. Bound proteins to the experimental and untreated control specimens were eluted in a stepwise manner with phosphatebuffered saline, 0.4 M phosphate buffer, and 1 M HCl. SDS-PAGE of dialyzed extracts showed that specific salivary proteins bound to the lesions, while virtually no protein bands were detected if the specimens were bleached. Western blotting showed that even statherin, which was more firmly bound than other proteins, was removed. In-office bleaching agent may be useful in treating enamel lesions for removing proteins bound to these lesions.

Three-dimensional X-ray micro-computed tomography analysis of polymerization shrinkage vectors in flowable composite.

The polymerization shrinkage of flowable resin composites was evaluated using air bubbles as traceable markers. Three different surface treatments i.e. an adhesive silane coupling agent, a separating silane coupling agent, and a combination of both, were applied to standard cavities. Before and after polymerization, X-ray micro-computed tomography images were recorded. Their superimposition and comparison allowed position changes of the markers to be visualized as vectors. The movement of the markers in the resin composite was, therefore, quantitatively evaluated from the tomographic images. Adhesion was found to significantly influence shrinkage patterns. The method used here could be employed to visualize shrinkage vectors and shrinkage volume.

Effect of the coating material on root dentin remineralization in vitro.

PURPOSE: A fluoride-releasing coating material containing surface pre-reacted glass-ionomer (S-PRG) filler has become commercially available. However, there has been no detailed investigation of its remineralization effects at various tooth surface regions. The remineralization effects of S-PRG filler-containing coating material at different sites of demineralized dentin surfaces in vitro were evaluated. METHODS: Baseline lesions were prepared on bovine root dentin surfaces by immersion in demineralization buffer and divided into four groups: (B)--baseline lesion; (P)--S-PRG filler-containing material; (V)--S-PRG filler-free coating material as negative control; and (X)--resin-modified glass- ionomer as positive control. Material was applied to half the lesion surface, then P, V and X were remineralized in a gel system. Mineral profiles, integrated mineral loss (IML) and lesion depth (LD) at four regions, i.e. 1--exposed dentin surface adjacent to the material; 2--at a distance from the material; 3--beneath the material near to the edge; and 4--at a distance from the edge, were analyzed by transversal microradiography. Data were analyzed using ANOVA and Games-Howell test with α = 0.05. RESULTS: B showed typical artificial demineralized lesion. The IMLs of V, P and X at regions 1 and 2, and P and X at region 3 were significantly lower than that of B, however, those of V at region 3 and the other three groups at region 4 were not significantly different from that of B. At region 1, P and X showed significantly lower IMLs than V. At region 2, the IML of X showed significantly lower IML than V. There was no significant difference between P and X. The LD values of V, P and X at all regions were not significantly different from that of B. Fluoride, strontium and silicate ions released from the S-PRG filler would provide a favorable environment for remineralization of the demineralized dentin in P.

Effect of enamel surface modification by novel aqueous phosphate-type fluoride surfactants.

Three novel aqueous fluoride surfactants (F4, F6, and F8) and a positive control (10F2S-3I) were applied to bovine enamel and the surface free energy was calculated by measuring the surface contact angles of three liquids: distilled water, α-bromonaphthalene and diiodomethane. The specimens were stored in water for 90 days, and then immersed in acetic acid/sodium acetate. The modified specimens recorded higher contact angles and lower surface free energy immediately after treatment than the control (p<0.05). Less calcium dissolved from the modified enamel surfaces than the control, with the F8-modified specimen registering significantly lower values than those of the F4, F6 and 10F2S-3I groups (p<0.05). These results suggest that the novel aqueous phosphate-type fluoride surfactant F8 is the most effective anti-cariogenic surface modifier.

Examination of bond strength and mechanical properties of Y-TZP zirconia ceramics with different surface modifications.

The purpose of our study was to evaluate the effects of surface modifications on the bond strength between veneering porcelains and Yttria-stabilized tetragonal zirconia (Y-TZP). In a bond strength tests, the effect of control, 70 µm alumina-sandblasting, 30 µm and 110 µm silica-coating of the Y-TZP surface on bonding were evaluated with veneering porcelains. In addition, the effect of surface modification on the flexural strength of Y-TZP was also evaluated. The data was analyzed using one-way ANOVA and Tukey test. All specimens showed bond strength values in excess of 25 MPa, the minimum allowed by ISO9693. In addition, significantly differences were found between the control and the 30 µm silica-coated. On the other hand the flexural strength of Y-TZP does not significantly difference for any surface modification. These results indicate that silica-coating may provide an effective pre-treatment for this enhancement of the bond strength while maintaining the strength of Y-TZP.

The caries-reducing benefit of fluoride-release from dental restorative materials continues after fluoride-release has ended.

OBJECTIVE: This study tested the hypothesis that the benefit of fluoride-releasing restorative materials continues even after their reserve of fluoride has been depleted. MATERIALS AND METHODS: Pits in perspex blocks simulating cavities were filled with either a fluoride-releasing or a non-fluoride-releasing restorative material and a dentin single-section was placed 1 mm from the edge of the filled pit. These combinations were exposed to an acid gel system. Each demineralized dentin section was separated from the adjacent material and immersed in fresh demineralizing solutions. Transversal microradiographs were taken following the two experimental periods. This study defined ΔΔZ as the increase of integrated mineral loss (ΔZ) during the second acid attack. RESULTS: The first acid attack substantially demineralized the near-surface region (depth < 40 µm) in all samples. The second acid attack, however, did not cause further demineralization in this near-surface region. Instead, it demineralized dentin deeper than 40-60 µm. The ΔΔZ of the material that did not release fluoride was significantly greater than that of fluoride-releasing materials. Negative correlations were found between ΔΔZ and the mineral volume% of the near-surface region and lesion body of the initial lesions. These results indicate that the dentin mineral in the near-surface region is chemically altered to become acid-resistant fluorapatite. In addition, lesion progression during the second period of demineralization, which was fluoride-free, may have been affected for the materials that have high mineral content of the surface layer and lesion body. CONCLUSIONS: It is concluded that dentin surrounding fluoride-releasing materials is protected against demineralization even after the fluoride release has diminished.

Anti-demineralization effect of a novel fluoride-releasing varnish on dentin.

PURPOSE: To investigate the laboratory anti-demineralization effect of a novel fluoride-releasing varnish containing surface reaction-type prereacted glass-ionomer (S-PRG) filler. METHODS: Paired specimens were cut from bovine root dentin. One of each pair was used for the S-PRG group, and the other served as a control (n = 6). A 1 x 3 mm test surface was made on each specimen with the fluoride-releasing varnish. The novel fluoride-releasing varnish is categorized as a two-bottle-type self-etch adhesive. These liquids were mixed, applied on the test surface, and light-cured for 10 seconds. As a control, an S-PRG filler-free varnish was applied in the same manner. Each specimen was immersed in 8% methylcellulose gel demineralization system (1.5 mM Ca, 0.9 mM PO4, 0.1 M acetic acid, pH 5.0) for 7 days at 3 degrees C. The mineral profiles and integrated mineral loss (IML) of the lesions were obtained by transversal microradiography and analytical software. RESULTS: The S-PRG group exhibited significantly thicker surface layer than the control group. Furthermore, the S-PRG group showed significantly lower IML (3,459 vol% xmicropm) than the control group (4,687 vol% xmicropm) ( P < 0.05, Welch's two-sample t-test). The novel fluoride-releasing varnish increased acid resistance of root dentin in the vicinity of the coated surface.

ADAMTSL6ß protein rescues fibrillin-1 microfibril disorder in a Marfan syndrome mouse model through the promotion of fibrillin-1 assembly.

Marfan syndrome (MFS) is a systemic disorder of the connective tissues caused by insufficient fibrillin-1 microfibril formation and can cause cardiac complications, emphysema, ocular lens dislocation, and severe periodontal disease. ADAMTSL6ß (A disintegrin-like metalloprotease domain with thrombospondin type I motifs-like 6ß) is a microfibril-associated extracellular matrix protein expressed in various connective tissues that has been implicated in fibrillin-1 microfibril assembly. We here report that ADAMTSL6ß plays an essential role in the development and regeneration of connective tissues. ADAMTSL6ß expression rescues microfibril disorder after periodontal ligament injury in an MFS mouse model through the promotion of fibrillin-1 microfibril assembly. In addition, improved fibrillin-1 assembly in MFS mice following the administration of ADAMTSL6ß attenuates the overactivation of TGF-ß signals associated with the increased release of active TGF-ß from disrupted fibrillin-1 microfibrils within periodontal ligaments. Our current data thus demonstrate the essential contribution of ADAMTSL6ß to fibrillin-1 microfibril formation. These findings also suggest a new therapeutic strategy for the treatment of MFS through ADAMTSL6ß-mediated fibrillin-1 microfibril assembly.

Synthesis and antimicrobial activity of quaternary ammonium silane coupling agents.

Fourteen novel silane coupling agents with a quaternary ammonium group introduced into the molecule, [CH(2)=CHCH(2)N(+)(CH(3))(C(n)H(2n+1))(CH(2))(3)Si(OCH(3))(3)]X(-) (n-X, n=10-18, X=Cl, Br, or I), were synthesized with the aim of using these agents to make material surfaces antimicrobial for a long period of time. Measurements of the minimum inhibitory concentrations (MIC) against 12 kinds of fungi and bacteria revealed that the coupling agent with a C(10) alkyl chain and Cl- or Br- counter-ion (10-Cl or 10-Br) has the highest antimicrobial activity among the n-X agents synthesized, but 14-Cl and 14-Br showed the highest activity on a modified porcelain plate.

Silica film coating method for veneering resin composite.

The preceramic polymer perhydropolysilazane (PHPS) is an attractive candidate as a coating material to prevent discoloration of veneering resin composites. At the present time, however, a practical method to apply this material is not available. The purpose of this study was to establish a low-temperature method for applying a silica film coating to a veneering resin composite. Two types of PHPS, NP and NL, were coated onto a veneering resin composite. The specimens were exposed to hydrogen peroxide vapor at 97°C, and the state of the conversion process was evaluated using FT-IR. With exposure to the hydrogen peroxide vapor, a 0.5-µm-thick silica film similar to that produced by baking was formed on the surface of the NP samples in 10 min, while a 0.2-µm-thick film was formed on the NL in 15 min. The silica coating method described in this study may mitigate the discoloration of veneering resin composite.

Study on ceramic coating on the enamel surface using a carbon dioxide laser.

The aims of this study were to evaluate a new restorative method using a carbon dioxide laser (CO(2)-laser) and to evaluate the acid resistance of teeth. Experimental calcium phosphate glass (CPG) powder and two low melting point ceramics (Finesse and zirconium silicate) were fused to enamel surfaces using a CO(2)-laser at an irradiation intensity of 1.0 watt for 30 seconds with a beam size of 0.49 mm at the focal point. The treated teeth were observed with a scanning electron microscope, and the acid resistance of the treated enamel surfaces was evaluated. The CPG fused successfully to the enamel surface, and the treated enamel surface showed high acid resistance compared with the low melting point ceramics and the non-irradiated surfaces. This system may lead to the development of new restorative methods that do not require the use of bonding agents.

Bonding strength of autopolymerizing resin to nylon denture base polymer.

This study aimed to investigate the shear bond strength of an autopolymerizing resin to a nylon denture base polymer (Lucitone FRS: LT) subjected to different surface treatments, and the results thereof compared with a heat-polymerizing resin and a polycarbonate polymer. Specimens were divided into five groups according to the surface treatment method: polishing (#600), sandblasting, adhesive primer application (resin primer), sandblasting + adhesive primer application, and tribochemical coating (Rocatec system). Following which, specimens were subjected to a shear bond strength test and Si concentrations were measured using an electron probe microanalyzer (EPMA). On shear bond strength, that of LT with tribochemical coating was significantly higher than the other groups. On EPMA results, the surface of LT with tribochemical coating was found to be covered with a silica film. Therefore, findings in this study indicated that silica-coating by Rocatec system was effective in improving the bond strength of nylon denture base polymer to autopolymerizing repair resin.

Fluoride release and recharge characteristics of denture base resins containing surface pre-reacted glass-ionomer filler.

The flexural strength, flexural modulus, and the amount of fluoride released from four experimental denture base resins containing 5, 10, 20 and 30 wt% surface pre-reacted glass-ionomer (S-PRG) filler added to the powder were evaluated. The mean flexural strength of the experimental resins, except the 30 wt%, and the flexural modulus of all the resins, complied with ISO 1567 requirements. In the 20 wt% resin, the amount of fluoride released in the initial phase was 1.88 microg/cm2/day, after which the level decreased. After recharging in a 9000 ppm fluoride solution for eight hours, the level of released fluoride increased markedly to 40.21 microg/cm2/16 hrs. Our results show that fluoride levels increased as a function of the S-PRG filler content. After the almost completely discharged resins were recharged, similar fluoride release occurred again. These results suggest that denture base resins containing S-PRG filler have great recharge and release capabilities which may assist in preventing root caries of abutment teeth.

Effect of denture base-resin with prereacted glass-ionomer filler on dentin demineralization.

The demineralization of dentin was studied when placed adjacent to one of four experimental denture base-resins. These experimental resins contained polymethylmethacrylate (PMMA) and 0, 5, 10, 20 or 30 wt% surface reaction-type prereacted glass-ionomer (S-PRG) filler, respectively. A dentin thin-section was sandwiched between these resins and subjected to demineralization for 1 wk. Microradiographic analyses showed that the mineral vol% of the surface was increased, and lesion formation was inhibited, in a dose-response relationship with the amount of S-PRG filler. Moreover, the mineral loss decreased, by up to 60%, with an increasing amount of filler. These results indicate that denture base-resins containing S-PRG filler possess a substantial inhibition capability against demineralization, and this may thereby assist in preventing root caries of abutment teeth.

Acid resistance induced by a new orthodontic bonding system in vitro.

The effect of fluoride-containing orthodontic resin bonding systems on acid resistance of adjacent enamel was evaluated using transversal microradiography. Four fluoride-containing orthodontic resin bonding systems: BeautyOrtho Bond (BO), BeautyOrtho Bond+Salivatect (BOS), Kurasper F (KP), Transbond XT (TB) and a resin-modified glass-ionomer (Fuji Ortho LC (FO)) were used. Superbond Orthomite (SB) was used as a non-fluoride material. Rectangular bovine enamel specimens (10X6 mm) were prepared. After curing the materials, nail varnish was applied to the enamel surfaces, leaving a gap of 1 mm from the cured material's periphery. The specimens were demineralized with 8% Methocel MC gel and 0.1 M lactic acid. BO, BOS, and FO revealed shallow lesions and distinct surface layers. The mineral losses of BO, BOS, and FO were significantly lower than those of TB, KP, and SB (p<0.05). In conclusion, the new system induced superior acid resistance in enamel surrounding orthodontic brackets.

Synthesis of bone formation deriving biosilanes.

Six silane coupling agents having amide group (biosilanes) were synthesized with the aim to construct the material surface that allows cells to be compatible with it without their destruction. These agents were expected to make a soft landing to cytoplasm through the hydrogen bonding between their amide groups and cells. Evaluations of cell affinity using glass substrates modified with the synthesized biosilanes revealed that many cells remain on the modified glass plate. In addition, the implantation into the body of immunodeficient mouse of a composite material composed of porous hydroxyapatite and osteoblast showed the formation of a bone-like structure.

Synthesis and antibacterial activity of quaternary ammonium salt-type antibacterial agents with a phosphate group.

Quaternary ammonium salts are frequently used as antibacterial agent that disrupts cell membrane through the binding of their ammonium cations to anionic sites in the outer layer tissue of bacteria. This article describes the synthesis of quaternary ammonium salt-type antibacterial agents with a phosphate group that strongly binds to hydroxyapatite and bromide ion as counterion. Evaluation of the antibacterial activity of the synthesized compounds in terms of minimum inhibitory concentration (MIC test) showed that the compounds exhibit an excellent antibacterial activity on a variety of bacteria including Gram-positive and Gram-negative bacteria, yeast, and fungi.