Search

Objective This study investigated the mechanical and in vitro biological properties (in immortalized human dental pulp stem cells (ihDPSCs)) of bioactive glass nanoparticle (BGN)-incorporated glass ionomer cement (GIC) with or without chitosan as a binder. Methods After the BGNs were synthesized and characterized, three experimental GICs and a control (conventional GIC) that differed in the additive incorporated into a commercial GIC liquid (Hy-bond, Shofu, Japan) were produced: BG5 (5 wt% of BGNs), CL0.5 (0.5 wt% of chitosan), and BG5 + CL0.5 (5 wt% of BGNs and 0.5 wt% of chitosan). After the net setting time was determined, weight change and bioactivity were analyzed in simulated body fluid (SBF) at 37 °C. Mechanical properties (compressive strength, diametral tensile strength, flexural strength and modulus) were measured according to the incubation time (up to 28 days) in SBF. Cytotoxicity (1 day) and biomineralization (14 days), assessed by alizarin red staining, were investigated using an extract from GIC and ihDPSCs. Data were analyzed using one-way analysis of variance (ANOVA) followed by Tukey’s post hoc test; p < 0.05. Results BGNs were sol–gel synthesized to be approximately 42 nm in diameter with a spherical morphology and amorphous structure. After the bioactivity and suspension ability of the BGNs were confirmed, all the experimental GIC groups had setting times of less than 6 min and approximately 1% weight loss after 28 days of incubation. In addition, BGNs incorporated into GIC (BG5 and BG5 + CL0.5) exhibited surface bioactivity. The mechanical properties were increased in the BGN-incorporated GICs compared to those in the control (p < 0.05). Without cytotoxicity, the biomineralization capacity was ranked in the order BG5, BG5 + CL0.5, control, and CL0.5 (p < 0.05). Significance BGN-incorporated GIC showed enhanced mechanical properties such as compressive, diametral tensile and flexural strength as well as in vitro biomineralization properties in ihDPSCs without cytotoxicity. Therefore, the developed BGN-incorporated GIC is a promising restorative dental material, although further in vivo investigation is needed before clinical application. [ABSTRACT FROM AUTHOR]

The impact of ZrO 2 content of the glass on the formation, properties and crystallization of glass ionomer cements (GICs) was investigated. Glass series based on SiO 2 –Al 2 O 3 –ZrO 2 –P 2 O 5 –CaO–CaF 2 system was synthesized and studied. The cements were characterized using a setting time, flexural strength, fracture toughness and in vitro biocompatibility test. The setting time of the ionomer cement increased with increasing the ZrO 2 content of the glass. The cements showed a slight decrease of cell biocompatibility with increase the ZrO 2 oxide content in the glasses. The results also showed that the flexural strength and the fracture toughness of the cements increased with immersion time and ZrO 2 oxide content. The crystallization characteristics of the glasses were investigated by differential scanning calorimeter (DSC) and X-ray diffraction analysis (XRD). The addition of ZrO 2 oxide in the glasses led to increase both the glass transition and crystallization temperatures. Fluorapatite [Ca 5 (PO 4 ) 3 F], mullite [Al 6 Si 2 O 13 ], cristobalite [SiO 2 ] and zircon [ZrSiO 4 ] phases were crystallized from the investigated glasses. The role played by the glass oxide constituents in determining the setting time, mechanical properties and crystallization characteristics of the prepared glass ionomer was discussed. [ABSTRACT FROM AUTHOR]

Abstract: Temporary skeletal anchorage devices (TSADs) provide anchorage for intruding the maxillary posterior teeth to correct an anterior open bite while simultaneously retracting the anterior teeth. The intrusion of posterior teeth with TSADs produces autorotation of the mandible and helps to correct a skeletal Class II pattern. Mandibular incisor extraction has been regarded as an additional treatment option in the correction of malocclusion. In this case report, a 37-year-old woman with a skeletal Class II malocclusion, anterior open bite and severe overjet was corrected with camouflage treatment. Both her occlusion and facial appearance were significantly improved after 23 months of treatment with TSADs and the extraction of her maxillary first premolars and one mandibular incisor. [Copyright &y& Elsevier]

Objective Although polymethyl methacrylate (PMMA) is widely used as a dental material, a major challenge of using this substance is its poor antimicrobial (anti-adhesion) effects, which increase oral infections. Here, graphene-oxide nanosheets (nGO) were incorporated into PMMA to introduce sustained antimicrobial-adhesive effects by increasing the hydrophilicity of PMMA. Methods After characterizing nGO and nGO-incorporated PMMA (up to 2 wt%) in terms of morphology and surface characteristics, 3-point flexural strength and hardness were evaluated. The anti-adhesive effects were determined for 4 different microbial species with experimental specimens and the underlying anti-adhesive mechanism was investigated by a non-thermal oxygen plasma treatment. Sustained antimicrobial-adhesive effects were characterized with incubation in artificial saliva for up to 28 days. Results The typical nanosheet morphology was observed for nGO. Incorporating nGO into PMMA roughened its surface and increased its hydrophilicity without compromising flexural strength or surface hardness. An anti-adhesive effect after 1 h of exposure to microbial species in artificial saliva was observed in nGO-incorporated specimens, which accelerated with increasing levels of nGO without significant cytotoxicity to oral keratinocytes. Plasma treatment of native PMMA demonstrated that the antimicrobial-adhesive effects of nGO incorporation were at least partially due to increased hydrophilicity, not changes in the surface roughness. A sustained antimicrobial-adhesive property against Candida albicans was observed in 2% nGO for up to 28 days. Significance The presence of sustained anti-adhesion properties in nGO-incorporated PMMA without loading any antimicrobial drugs suggests the potential usefulness of this compound as a promising antimicrobial dental material for dentures, orthodontic devices and provisional restorative materials. [ABSTRACT FROM AUTHOR]

Objective Poly(methyl methacrylate) (PMMA) used as removable denture bases or orthodontic appliances has relatively poor antimicrobial properties, which accelerate oral infection and induce unfavorable odors. Mesoporous silica nanoparticles (MSNs) have been highlighted as a potential additive to overcome this issue because of their drug-loading capacity. Here, we present the long-term antimicrobial effect of MSN-incorporated PMMA with drug-loading capacity. Methods After the MSNs were characterized, MSN incorporation into chemically activated PMMA (0.5, 1, 2.5 or 5 wt%) relative to the methyl methacrylate powder by mass was fabricated into a rectangular specimen (1.4 × 3.0 × 19.0 mm) for a 3-point flexural test at a speed of 1 mm/min or a disk ( ∅ = 11.5 mm and d = 1.5 mm) for investigation of its antimicrobial effects. Results A typical spherical morphology with a well-ordered mesoporous structure of the MSNs was visualized and is beneficial for loading drugs and combining in matrixes. Among the tested levels of MSN incorporation in PMMA (0.5, 1, 2.5 or 5 wt%), only 5 wt% decreased the flexural strength (p < 0.05), whereas the flexural modulus was not significantly decreased (p > 0.05). The surface roughness and surface energy were increased with 2.5 wt% or 5 wt% incorporation. An anti-adherent effect against Candida albicans and Streptococcus oralis after 1 h of attachment was only observed with 2.5 and 5 wt% incorporation compared to a lack of MSNs (p < 0.05). A long-term antimicrobial effect was observed for 2 weeks with 2.5 wt% MSN-incorporated PMMA when amphotericin B was loaded into the MSNs on the PMMA surface. Significance The long-term antimicrobial performance after loading amphotericin B into the MSN-incorporated PMMA suggests the potential clinical usefulness of MSN-incorporated PMMA resin. [ABSTRACT FROM AUTHOR]

Objectives Even though polymethyl methacrylate (PMMA) resin is widely used as a dental material, it has poor microbial anti-adhesive properties, which accelerates oral infections. In this investigation, silver-sulfadiazine (AgSD)-loaded mesoporous silica nanoparticles (Ag-MSNs) were incorporated into PMMA to introduce long-term microbial anti-adhesive effects and to make PMMA a rechargeable resin. Methods After characterization of the Ag-MSNs in terms of their mesoporous characteristics and drug loading capacity, the 3 point flexural test and hardness were evaluated in PMMA incorporating Ag-MSNs (0.5, 1, 2.5 and 5%). Anti-adhesive effects were observed for Candida albicans and Streptococcus oralis with experimental specimens for up to 28 days and after recharging with AgSD. Results A typical spherical morphology and high mesoporosity were observed for the MSNs used for loading AgSD. Incorporation of Ag-MSNs into PMMA (0.5, 1, 2.5 and 5%) sustained its flexural strength but increased its surface hardness. Anti-adhesive effects were observed after 1 h of exposure to both microbial species, and the effects accelerated with increasing Ag-MSN incorporation into PMMA. Long-term microbial anti-adhesive effects were observed for up to 14 days, and further long-term (7 days) anti-adhesive effects were observed after reloading the Ag-MSN-incorporated PMMA (aged for 28 days) with AgSD; these effects were largely caused by released silver ions and partially by changes in surface hydrophilicity. No cytotoxicity to keratinocytes was observed. Conclusions The improved mechanical properties and the prolonged microbial anti-adhesive effects, which lasted after reloading of the drug, suggest the potential usefulness of Ag-MSN-incorporated PMMA as a microbial anti-adhesive dental material. Significance Ag-MSN-incorporated PMMA can be used as a microbial anti-adhesive dental material for dentures, orthodontic devices and provisional restorative materials. [ABSTRACT FROM AUTHOR]