Controlled release, antimicrobial activity, and oral mucosa irritation of cetylpyridinium chloride-montmorillonite incorporated in a tissue conditioner.

This study examined the controlled release of cetylpyridinium chloride (CPC) from a tissue conditioner (TC) containing CPC-montmorillonite (CPC-Mont), the associated antimicrobial activity, and oral mucosa irritation. The CPC release test was performed daily for 28 days in three test solutions: distilled water, 0.2 M NaCl, and 0.2 M HCl. The antimicrobial activities for 7, 14, 21, and 28 days against Candida albicans, Staphylococcus aureus, and Streptococcus mutans were assessed according to the JIS Z 2801/ISO 22196 standard. An oral mucosa irritation test was conducted using cheek pouches in five male hamsters according to the ISO 10993-10:2010 standard. The amount of CPC released each day and the cumulative amount released over 28 days (6.12 mg) were less than the daily safe maximum of sore throat medicines (8 mg). Additionally, TC with CPC-Mont could sustain antimicrobial activity against adherent bacteria for 14 days and has no oral mucosa irritation potential.

Optimizing glass-ceramic bonding incorporating new silane technology in an experimental universal adhesive formulation.

OBJECTIVE: Incorporating silane-coupling agent into universal adhesives (UAs) to simplify adhesive luting of glass-ceramic restorations appeared ineffective due to silane's instability in an acidic aqueous solution. This study aimed to evaluate new silane technology added to an experimental UA to be bonded to glass ceramics without separate prior silanization. METHODS: Combined silane technology, consisting of 3-(aminopropyl)triethoxysilane (APTES) and γ-methacryloxypropyltriethoxysilane (γMPTES), was incorporated into an experimental UA formulation, being referred to as ADH-XTE (3M Oral Care). Immediate and aged shear bond strength (SBS) of ADH-XTE onto as-milled ('AM'), tribochemical silica-coated ('TSC'), HF-etched ('HF'), and mirror-polished ('MP') glass-ceramic CAD/CAM blocks (IPS e.max CAD) with/without separate silanization was measured (n = 10/group). The control adhesives included Scotchbond Universal ('SBU') and Scotchbond 1 XT ('SB1-XT'). The glass-ceramic surface topography and the fractography of the SBS-debonded specimens were observed by SEM. RESULTS: Without separate prior silanization, the experimental UA ADH-XTE, containing combined APTES/γMPTES silane technology, significantly outperformed the glass-ceramic bonding efficiency of its silane-containing SBU precursor, while it performed equally effective as SBU applied with prior silanization. Upon aging, significant reduction in SBS was recorded when ADH-XTE was bonded to TSC glass-ceramic surfaces (p < 0.05), while not to HF ones. Notably, the lowest SBS was obtained when the UAs were bonded to AM and MP glass-ceramic surfaces, in particular when applied without separate prior silanization (p < 0.05). SIGNIFICANCE: The glass-ceramic bonding capacity of the new combined APTES/γMPTES silane-containing UA ADH-XTE surpassed that of its SBU precursor. HF etching remains needed to durably bond to glass-ceramics.

Initial curing characteristics of composite cements under ceramic restorations.

PURPOSE: To assess the degree of conversion (DC) of dual-curing composite cements when cured through ceramic-veneered zirconia disks. METHODS: Portions of mixed cement, either G-CEM LinkForce (GC), Panavia V5 (Kuraray Noritake) or ResiCEM (Shofu), were placed on the ATR crystal of a Fourier Transform Infrared Spectroscope (FTIR; iS50, Thermo Scientific) and squeezed to a 100-µm film thickness using a microscopy cover glass. DC (%) of the composite cements applied in self-curing mode was measured in the dark at 37°C. Following the dual-curing mode, the cements were light-cured directly (positive control) or through a ceramic-veneered zirconia disk (0.5-mm thick zirconia with a 1.0-mm thick veneering ceramic) for 40 sec using two light-curing units (G-Light Prima 2, GC; PenCure, Morita). Per experimental group, 5 tests were conducted to measure DC in self-cure and dual-cure mode (n=5). FTIR spectra of the composite cement films were acquired to determine DC every min up to 30 min. DC of the composite cements was statistically compared using two-way repeated-measures ANOVA (α=0.05). RESULTS: For all cements investigated, the self-curing mode resulted in significantly lower DC at 10, 20 and 30 min than the light-curing mode. When the composite cements were light-cured through the zirconia disk, DC at 30 min dropped significantly for ResiCem (Shofu), while not for Panavia V5 (Kuraray Noritake) and G-CEM LinkForce (GC). CONCLUSIONS: Self-curing slows down polymerization but does not reach for all composite cements the highest (light-cured) DC. Ceramic-veneered zirconia-based restorations may affect DC of some composite cements.

Bone turnover markers to assess jawbone quality prior to dental implant treatment: a case-control study.

BACKGROUND: Bone quality is as important as bone mineral density in terms of bone strength. Bone turnover markers (BTMs) are clinical indicators of bone quality. In implant dentistry, bone quality is considered equivalent to bone density on radiographic assessments. The purpose of this study was to determine whether the BTM values are reflected in jawbone condition by evaluating the relationship at baseline and during follow-up in patients with prosthodontic implants. Computed tomography (CT) scans were obtained and BTM (osteocalcin, bone-specific alkaline phosphatase, pyridinoline cross-linked carboxyterminal telopeptide of type I collagen, and crosslinked N-telopeptide of type I collagen) levels in blood samples were measured in partially edentulous eighteen patients before implant surgery. During the follow-up observation after implant surgery, marginal bone loss (MBL) was measured on dental radiography. We investigated the relationship between the presence of BTM abnormalities and radiographic bone density. RESULTS: More women than men had abnormal BTM values. Bone turnover was accelerated in the group of women with abnormal BTM values. The density of cancellous bone at the implant placement site was significantly lower in the patients with abnormally high BTM values than in their counterparts with BTM values in the normal range. CONCLUSIONS: Female patients who undergo implant treatments may have reduced bone quality; evaluations of bone strength will require assessments of both BTMs and the density of cancellous bone.

Antimicrobial effects of viscous mouthrinses containing cetylpyridinium chloride and isopropyl methylphenol.

PURPOSE: To evaluate the in vitro antimicrobial effect of low- and high-viscosity experimental mouthrinses containing cetylpyridinium chloride (CPC) and 4-isopropyl-3-methylphenol (IPMP) on Streptococcus pneumoniae, Klebsiella pneumoniae, Porphyromonas gingivalis, Streptococcus mutans, and Candida albicans. METHODS: Low- and high-viscosity experimental mouthrinses containing 0.05% CPC and 0.1% IPMP were fabricated. Non-viscous mouthrinses containing either CPC- or IPMP were used as controls. The antimicrobial activity (sterilization or exposure time) of mouthrinses was evaluated based on the bactericidal criterion of <10¹ viable cells in 0.1 mL of culture medium. RESULTS: The sterilization time of the low-viscosity experimental mouthrinse was shorter than that of the high-viscosity mouthrinse. However, whereas a 10-minute exposure to the low-viscosity mouthrinse resulted in no viable cells of C. albicans, neither the CPC- or IPMP mouthrinses had an antimicrobial effect for the same exposure time. These findings show that the low-viscosity experimental mouthrinse containing anodal CPC and neutral IPMP exhibited superior antimicrobial effects against pneumonia- and oral infection-related bacteria compared with the control mouthrinses. CLINICAL SIGNIFICANCE: In Japan, the oral care with the low-viscosity experimental mouthrinse containing CPC and IPMP as alternatives to those based on chlorhexidine are available for preventing the development of pneumonia- and oral infection-related bacteria.

A web-based survey of denture adhesive use among denture wearers 40 years of age and older.

The purpose of this study was to clarify the usage and understanding of denture adhesives among 1,825 denture wearers, aged 40 years and older in Japan, using a web-based survey. The NTTCom Online survey (a closed investigation) was conducted over a period of 4 days using a 13-item questionnaire about denture adhesives. Results showed that 67.1% of the respondents were satisfied with their dentures; 81.5% of respondents knew about denture adhesive, but only 347 (19.0%) had used the product. Products used by the 347 denture wearers included cream type (79.7%), cushion type (16.2%), and powder type (3.2%). The most common reason for the selection of a particular type was "Saw the product" (59.9%), followed by "Saw an advertisement" (19.3%), and "Explanation at a dental clinic" (8.4%). The response of "Ill-fitting denture" significantly affected the response of "Use of denture adhesives" (chi-square test; P < 0.001). Moreover, the sensitivity (0.56) was lower than the specificity (0.75). These findings show that denture adhesives were not always necessary for those with ill-fitting dentures.

Development of tissue conditioner containing cetylpyridinium chloride montmorillonite as new antimicrobial agent: Pilot study on antimicrobial activity and biocompatibility.

PURPOSE: The mechanical properties, antimicrobial activity, and biocompatibility of a novel antimicrobial tissue conditioner containing cetylpyridinium chloride with montmorillonite (CPC-Mont) were evaluated. METHODS: To examine the mechanical properties of the novel material, hardness, consistency, and penetration tests were conducted. Antimicrobial activity against Candida albicans (C. albicans) and Staphylococcus aureus (S. aureus) was evaluated. Cell viabilities of fibroblasts and epithelial cells using eluates from materials were measured to evaluate cytotoxicity. In addition, to assess tissue response, animal experiments were conducted. RESULTS: The hardness test results were similar to those of other commercially available materials. The novel tissue conditioner showed good antimicrobial activity against C. albicans and S. aureus compared with other materials. This effect was sustained for a week for C. albicans. In the case of S. aureus, microbial growth was suppressed for up to 3 weeks. Cell viability of the novel material for the eluate at 1 day was significantly less than those of other material for both cells. However, the cell viability at 7 days showed no significant difference. Animal experiments demonstrated that inflammatory responses around materials were not observed on the oral mucosa as other material. CONCLUSION: Within the limitations of this in vitro and in vivo study, the results suggest that the newly developed tissue conditioner containing CPC-Mont has not only excellent antimicrobial properties, but also the same mechanical properties and biocompatibility as tissue conditioners on the market.

PCBs and PBDEs in microplastic particles and zooplankton in open water in the Pacific Ocean and around the coast of Japan.

PCBs and PBDEs in microplastics and zooplankton collected in surface water at 27 locations in the Pacific Ocean and around the coast of Japan were investigated. Both PCBs and PBDEs were observed in buoyant microplastics, even in smaller particles of 0.315-1 mm. Concentrations of Σ13 PCBs were 0.04-124 ng/g, and were higher in urban bay areas such as Tokyo Bay. Sporadic moderate to high concentrations of PBDEs were observed in both urban-offshore and rural-offshore locations, consisting mostly of higher-brominated congeners. From the latter, BDE 209 ranged from not detected to 2158 ng/g. The microplastic-to-zooplankton abundance ratio threshold was 0.6 for PCBs and 0.08 for PBDEs, above which exposure would be greater from microplastics than from zooplankton.

Bonding Efficacy of a New Self-Adhesive Restorative onto Flat Dentin vs Class-I Cavity-bottom Dentin.

PURPOSE: This study investigated the bonding efficacy of a new so-called self-adhesive composite hybrid onto flat (FLAT) and high C-factor class-I cavity-bottom (CAVITY) dentin. MATERIALS AND METHODS: The immediate and aged (50,000 thermocycles) microtensile bond strength (µTBS) to FLAT and CAVITY dentin of the experimental self-adhesive bulk-fill restorative (K-0180 ASAR pilot [ASAR-pilot], Dentsply Sirona) was compared to that of two universal adhesives applied in self-etch mode and combined with a bulk-fill composite (Prime&Bond Elect/QuiXfil [P&Be/QuiXF], Prime&Bond Active/QuiXfil [P&Ba/QuiXF], both Dentsply Sirona), two pre-conditioned materials (Activa Bioactive-Restorative [Activa], Pulpdent; Fuji II LC Improved [Fuji2LC], GC); and one bulk-fill glass-hybrid restorative (Equia Forte Fil [EquiaF], GC). Statistically significant differences were recorded using Welch's ANOVA with Games-Howell contrast (p < 0.05). RESULTS: No significant difference in immediate µTBS was recorded when the restorative materials were applied onto FLAT dentin, except for Activa_FLAT and EquiaF_FLAT. When bonded to CAVITY dentin, the significantly highest µTBS was recorded for Fuji2LC_CAVITY (layer filled), and was not significantly different only from P&Ba/QuiXF_CAVITY. Upon aging, the highest µTBS to flat dentin was achieved by ASAR-pilot_FLAT, which was not significantly different from P&Be/QuiXF_FLAT and Fuji2LC_FLAT. No significant difference between immediate and aged µTBS was recorded for ASAR-pilot when bonded onto FLAT or CAVITY dentin; the latter, however, was associated with low bond strength. CONCLUSION: Favorable bonding performance was found for the new self-adhesive bulk-fill composite hybrid ASAR-pilot when bonded to flat dentin. However, much lower bond strength was recorded when ASAR-pilot was bonded to high C-factor cavity-bottom dentin.

Effective UV/Ozone irradiation method for decontamination of hydroxyapatite surfaces.

The purpose of this study was to establish whether UV/ozone (O3) irradiation method can effectively decontaminate hydroxyapatite surfaces, including those modified by the treatment with 30% phosphoric acid solution through morphological and chemical surface analyses (surface roughness, X-ray photoelectron spectroscopy and wettability), and to evaluate the in vitro response of osteoblast-like MC3T3-E1 cells to the modified hydroxyapatite surface decontaminated via this method. The amount of carbon and the contact angle of hydroxyapatite surfaces were significantly decreased by UV/O3 irradiation that lasted for ≥ 5 and ≥ 3 min, respectively (P < 0.01). Additionally, 7-day storage of H3PO4-modified hydroxyapatite surface decontaminated with 5-min irradiation did not affect contact angle values (P > 0.05). MC3T3-E1 cell proliferation, differentiation (as assessed by relative ALP and OCN mRNA levels), and mineralisation were significantly promoted on irradiated surfaces (P < 0.05). These findings show that UV/O3 irradiation for ≥ 5 min significantly decontaminated H3PO4-modified hydroxyapatite surface, improved its wettability, and facilitated osteoblast growth and function.

Enhanced Osseointegration of a Modified Titanium Implant with Bound Phospho-Threonine: A Preliminary In Vivo Study.

Implant surface topography is a key factor in achieving osseointegration. l-Threonine can be chemically and stably bonded to titanium surfaces by phosphorylation. This study investigated the degree of in vivo osseointegration of an implant with a novel o-phospho-l-threonine (p-Thr)-binding surface. MC3T3-E1 cells were seeded on the p-Thr binding surface and machined surface disks, and initial cell attachment was evaluated. p-Thr-binding and machined surface implants were tested in vivo by implantation into the femurs of three male New Zealand white rabbits, and the osseointegration was assessed by measurement of removal torque (RT) and bone-implant contact (BIC) ratio. Initial cell attachment was greater for the p-Thr-binding than for the machined surface implant group (P < 0.05). In addition, RT and BIC values were higher for the p-Thr-binding surface than for the machined surface (P < 0.05). These results indicate that our implant with a p-Thr-binding surface can achieve enhanced osseointegration.

Microplastics in Sediment Cores from Asia and Africa as Indicators of Temporal Trends in Plastic Pollution.

Microplastics (<5 mm) were extracted from sediment cores collected in Japan, Thailand, Malaysia, and South Africa by density separation after hydrogen peroxide treatment to remove biofilms were and identified using FTIR. Carbonyl and vinyl indices were used to avoid counting biopolymers as plastics. Microplastics composed of variety of polymers, including polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethyleneterphthalates (PET), polyethylene-polypropylene copolymer (PEP), and polyacrylates (PAK), were identified in the sediment. We measured microplastics between 315 µm and 5 mm, most of which were in the range 315 µm-1 mm. The abundance of microplastics in surface sediment varied from 100 pieces/kg-dry sediment in a core collected in the Gulf of Thailand to 1900 pieces/kg-dry sediment in a core collected in a canal in Tokyo Bay. A far higher stock of PE and PP composed microplastics in sediment compared with surface water samples collected in a canal in Tokyo Bay suggests that sediment is an important sink for microplastics. In dated sediment cores from Japan, microplastic pollution started in 1950s, and their abundance increased markedly toward the surface layer (i.e., 2000s). In all sediment cores from Japan, Thailand, Malaysia, and South Africa, the abundance of microplastics increased toward the surface, suggesting the global occurrence of and an increase in microplastic pollution over time.

Novel Development of Phosphate Treated Porous Hydroxyapatite.

Phosphoric acid-etching treatment to the hydroxyapatite (HA) surface can modify the solubility calcium structure. The aim of the present study was to develop phosphate treated porous HA, and the characteristic structures and stimulation abilities of bone formation were evaluated to determine its suitability as a new type of bone graft material. Although the phosphoric acid-etching treatment did not alter the three-dimensional structure, a micrometer-scale rough surface topography was created on the porous HA surface. Compared to porous HA, the porosity of phosphate treated porous HA was slightly higher and the mechanical strength was lower. Two weeks after placement of the cylindrical porous or phosphate treated porous HA in a rabbit femur, newly formed bone was detected in both groups. At the central portion of the bone defect area, substantial bone formation was detected in the phosphate treated porous HA group, with a significantly higher bone formation ratio than detected in the porous HA group. These results indicate that phosphate treated porous HA has a superior surface topography and bone formation abilities in vivo owing to the capacity for both osteoconduction and stimulation abilities of bone formation conferred by phosphoric acid etching.

Bioactive surface modification of hydroxyapatite.

The purpose of this study was to establish an acid-etching procedure for altering the Ca/P ratio of the nanostructured surface of hydroxyapatite (HAP) by using surface chemical and morphological analyses (XPS, XRD, SEM, surface roughness, and wettability) and to evaluate the in vitro response of osteoblast-like cells (MC3T3-E1 cells) to the modified surfaces. This study utilized HAP and HAP treated with 10%, 20%, 30%, 40%, 50%, or 60% phosphoric acid solution for 10 minutes at 25°C, followed by rinsing 3 times with ultrapure water. The 30% phosphoric acid etching process that provided a Ca/P ratio of 1.50, without destruction of the grain boundary of HAP, was selected as a surface-modification procedure. Additionally, HAP treated by the 30% phosphoric acid etching process was stored under dry conditions at 25°C for 12 hours, and the Ca/P ratio approximated to 1.00 accidentally. The initial adhesion, proliferation, and differentiation (alkaline phosphatase (ALP) activity and relative mRNA level for ALP) of MC3T3-E1 cells on the modified surfaces were significantly promoted (P < 0.05 and 0.01). These findings show that the 30% phosphoric acid etching process for the nanostructured HAP surface can alter the Ca/P ratio effectively and may accelerate the initial adhesion, proliferation, and differentiation of MC3T3-E1 cells.

Maximal voluntary tongue pressure is decreased in Japanese frail elderly persons.

BACKGROUND AND OBJECTIVE: To quantitatively estimate tongue function, we developed a handy device for intraoral pressure measurement. The objective of this study was to assess maximum voluntary tongue pressure (MVTP) in Japanese frail elderly persons receiving nursing care services. MATERIALS AND METHODS: The study included 42 men and 87 women, aged 58-100 years. To record MVTP, the participants were asked to compress the balloon (diameter: 18 mm) of the disposable intraoral pressure probe onto their palates for 7 s using the maximum voluntary effort of the tongue. Pressures were recorded three times at 1 min intervals. RESULTS: Maximum voluntary tongue pressure was successfully measured in 111 persons. Mean (standard deviation) MVTP was 18 (12) kPa, with a range of 0-63 kPa. The remaining 18 persons could not accurately follow our instructions and MVTP could not be measured. CONCLUSION: In comparison with the reported standard value using the same device, the frail elderly persons included in our study were found to exert less MVTP than healthy dentate individuals. These results suggest the need for proper quantitative evaluation of oral function, including tongue capacity, at nursing care facilities.

Preoperative computed tomography-derived bone densities in hounsfield units at implant sites acquired primary stability.

The purpose of this study was to evaluate preoperative CT-derived bone densities in Hounsfield units (HU) at implant sites that acquired primary stability, and to compare these values to the optimal bone densities proposed in the literature. Fifty-one patients, 18 males (37 implant sites) and 33 females (67 implant sites) between 2003 and 2010 were assessed. CT data for different jaw sections, regions, and operating procedures were compared using the Kruskal-Wallis test and Scheffe's test for multiple comparisons (P < 0.05). The mean bone density in the maxilla was significantly lower than that in the mandible (P < 0.05); the mean bone densities in the 4 jaw regions decreased in the following order: anterior mandible > anterior maxilla > posterior mandible > posterior maxilla. The bone densities assessed by HU fell into the range of optimal bone densities associated with acquired primary implant stability proposed in the literature.

Detection of synthetic RGDS(PO3H2)PA peptide adsorption using a titanium surface plasmon resonance biosensor.

The purpose of this study was to measure the time-dependent chemical interaction between synthetic RGDS(PO(3)H(2))PA (P-RGD) peptide and titanium surfaces using a titanium surface plasmon resonance (SPR) biosensor and to determine the degree of peptide immobilization on the surfaces. An SPR instrument for 'single-spot' analysis was used for nanometer-scale detection of biomolecular adsorption using a He-Ne laser light according to Knoll's method. The oxidized titanium surface was etched when exposed to H(3)PO(4) solutions with a pH of 2.0 or below. The amount of P-RGD adsorbed at pH 1.9 was approximately 3.6 times as much as that at pH 3.0 (P < 0.05). P-RGD naturally adsorbed on the oxidized titanium surface as a consequence of the bonding and dissociation mechanism of the phosphate functional group. Furthermore, the control of pH played a very important role in the interaction between P-RGD and the surface. These findings show that pH control may promote progressive binding of biomolecules with the phosphate functional group to the titanium surface.

Degree of immobilization of synthetic RGDS(PO(3)H(2))PA peptides on titanium surfaces.

The purpose of this study was to characterize the chemical interaction between titanium surfaces and the peptide RGDS(PO(3)H(2))PA (P-RGD) synthesized from RGD peptide (RGD) and o-phospho-L-serine (P-Ser), and to determine the degree of peptide immobilization on the titanium surface. X-ray photoelectron spectroscopy showed that the adsorption amount of RGD was significantly smaller than those of P-Ser and P-RGD (p<0.05). Furthermore, although it appeared that P-RGD bonded to the surface, ultrasonic rinsing with water caused it to dissociate, releasing RGD and leaving only S(PO(3)H(2))PA bonded to the surface. These findings show that although it remains difficult to obtain a stable P-RGD layer, the phosphate functional group greatly improves immobilization of the molecule on titanium surfaces.