The objectives were to develop a novel rechargeable cement containing amorphous calcium-phosphate nanoparticles (nanoACP) to suppress tooth decay. Five cements were made with: (1) 60% glass particles (experimental control); (2) 40% glass+20% nanoACP; (3) 30% glass+30% nanoACP; (4) 20% glass+40% nanoACP; (5) 10% glass+50% nanoACP. Groups 1–4 had enamel bond strengths similar to Transbond XT (3M) and Vitremer (3M) (p>0.1). The nanoACP cement had calcium and phosphate ion release which increased with increasing nanoACP fillers. The recharged cement had substantial ion re-release continuously for 14 days after a single recharge. Ion re-release did not decrease with increasing recharge/re-release cycles. Groups 3–5 maintained a safe pH of medium (>5.5); however, control cements had cariogenic pH of medium (<4.5) due to biofilm acid. Therefore, nanoACP cement (1) had good bond strength to enamel, (2) possessed calcium and phosphate ion recharge/re-release capability, and (3) raised biofilm pH to a safe level to inhibit caries.
The present study was designed to investigate the biodegradation behavior of Mg alloy plates in the maxillofacial region. For in vitro analysis, the plates were immersed in saline solution and simulated body fluid. For in vivo, the plates were implanted into the tibia, head, back, abdominal cavity, and femur and assessed at 1, 2, and 4 weeks after implantation. After implantation, the plate volumes and the formed insoluble salt were measured via micro-computed tomography. SEM/EDX analysis of the insoluble salt and histological analysis of the surrounding tissues were performed. The volume loss of plates in the in vitro groups was higher than that in the in vivo groups. The volume loss was fastest in the abdomen, followed by the head, back, tibia, and femur. There were no statistically significant differences in the insoluble salt volume of the all implanted sites. The corrosion of the Mg alloy will be affected to the surrounding tissue responses. The material for the plate should be selected based on the characteristic that Mg alloys are decomposed relatively easily in the maxillofacial region.
The aim of this study was to evaluate in vitro detection of enamel white spot lesions around orthodontic brackets using swept-source optical coherence tomography (SS-OCT). Twenty-four clear orthodontic brackets were bonded onto the enamel surface of bovine incisor specimens using three types of orthodontic resin adhesives: non-fluoridated, fluoridated, and fluoridated light cured. The specimens were subjected to artificial demineralization. SS-OCT images were captured before demineralization and at 24 h and 1 week after demineralization. Lesion depth (LD) was measured and analyzed using Image J software. Results revealed significant increases in LD with time in all three groups. LDs were, however, significantly smaller in the fluoridated adhesive groups than in the non-fluoridated group. In addition, SS-OCT was validated for the detection of micro-leakage and white spot lesions beneath and around the orthodontic brackets.
The purpose of this study was to evaluate the early tensile bond strengths of three different resin cements; Super Bond C&B (conventional and quick type) and ResiCem to a CAD/CAM composite block. A CAD/CAM composite block (Shofu Block HC) was ground and silanized according to the manufacturers’ instructions before cementation. A conventional tensile bond strength test (Ø: 4 mm) was performed 10 min, 1 h and 24 h after bonding. Super Bond C&B (quick type) showed the highest bond strength at 24 h. However, results of a three-point bend test showed the mechanical properties were weaker for the Super Bond C&B cements compared with composite cement, Resicem. The 4-META/MMA-TBB resin is a suitable resin cement to bond to a CAD/CAM composite block.
This study investigates the effects of various beverages on the wettability, microhardness, and color stability of aesthetic dental restorative materials. A contact angle analyzer, Vickers hardness tester, and spectrophotometer were used to characterize the properties of the materials and a total of 225 specimens were prepared: 75 each for a resin composite, compomer, and giomer. Ingestion of energy drinks and cola caused the greatest deterioration in wettability and microhardness, and coffee caused the most significant color change. In addition, the change in the resin composite was lower than that of the other restorative materials. The extent of change in the restorative materials increased with duration and frequency of contact with the beverages, so a reduction in the frequency of ingestion of these beverages is recommended.
In this study, we evaluate the effect of co-doping with TiO2 nanoparticles and sisal cellulose nanocrystals (CNCs) on the physical and biological properties of a conventional glass-ionomer cement (GIC). Test samples were characterized by scanning electron microscopy, and Fourier-transform infrared spectroscopy, and subjected to mechanical tests to evaluate the mechanical performances. Antimicrobial activity was evaluated against Candida albicans, and cytotoxicity experiments were conducted using L-929 cells. Unmodified GIC served as a control. Compared with the control group, the co-doped group demonstrated an increased compressive strength of 18.9%, an increased shear bond strength of 51%, the dissolution decreased by 18.3%, the volume wear rate was reduced by 5%. The antifungal effect against C. albicans was increased by 22%. In cytotoxicity experiments, the co-doped group had a slightly negative effect on the viability of L-929 cells.
Directly milling zirconia computer-aided design (CAD)/computer-aided manufacturing (CAM) crowns from fully sintered zirconia blocks using a five-axis laser milling system, compared with three-axis milling and full sintering by heating milled semi-sintered crowns, was investigated. The mechanical characteristics of zirconia specimens were similar across groups. The order of the marginal gap was three-axis>conventional (lingual thickness of 1.5 mm>0.5 mm)>five-axis group (close to zero). The marginal shape was almost perfectly circular in all groups. The internal corner shape and gap were almost perfect for the five-axis milled crown but not for conventional and three-axis crowns. The roundness of the marginal and internal shapes was almost perfect in the five-axis milling group but not for the three-axis and conventional groups. These small distortions result in large marginal gaps. Results of the present study suggest the superiority of the five-axis milling system in creating a zirconia prosthesis.
The aim of the present study was to evaluate microhardness, mineral recovery and the enamel surface after the application of topical fluoride to artificial dental caries. Twenty-five bovine enamel blocks were prepared for artificial caries-like lesions and randomly divided into five groups (n=5): untreated (C control), 1.23% acidulated phosphate fluoride gel (APG), 2% neutral fluoride gel (NFG), 1.23% acidulated fluoride mousse (AFM) and fluoride varnish (5% Duraphat, DFV). Knoop microhardness (KHN) was evaluated after 7 and 14 days of treatment as well as 1 week after 28 days of treatment. Electron and confocal microscopy and energy dispersive spectroscopy were performed. KHN data were treated with two-way ANOVA (material×time) and Tukey’s test at a 5% significance level. Differences were found among groups over time (p<0.001). Microhardness varied after 7 and 14 days of treatment and remained stable 1 week after 28 days of treatment. Mineral recovery and enamel topography varied among groups, with the fluoride varnish achieving the most uniform topography.
The evaluation of the photocatalysis of visible light activated titanium dioxide employed in hydrogen peroxide (H2O2) was carried using seven H2O2 solutions (3.5 and 35%) and/or methylene blue (MB), with or without light irradiation (LI); the absorbance of MB was the bleaching indicator. Color analysis was performed on bovine teeth (n=12) using two different concentrations of H2O2, 6 and 35% associated with titanium dioxide (TiO2). Data were analyzed with one and two-way ANOVA, and significance level of p<0.05. Solutions containing MB, H2O2 at 3.5 or 35%, and TiO2, followed by LI, showed significant difference when compared with other groups. Greater MB reduction was found in 35% concentration. H2O2 35%+TiO2 gel showed no difference in comparison to control group. All groups for the color analysis assay showed ΔE higher than 3.3. In conclusion, TiO2 and H2O2 association is a promisor alternative for reducing the clinical time of in-office dental bleaching.
This in vitro study aimed to evaluate the effect of two different polymer-based CAD/CAM materials; resin-nano ceramic (Lava Ultimate [LVU]) and composite (CERASMART [CS]), their different surface pre-treatments, and use of different resin cements on the µTBS of adhesively bonded CAD/CAM onlays to dentin. CAD/CAM materials were cut into slabs and divided into five groups according to the surface pre-treatments applied: Silane Primer, OptiBond XTR adhesive, Silane Primer+OptiBond XTR adhesive, Single Bond Universal (SBU), and RelyX Ceramic Primer+SBU. The LVU and CS specimens were bonded to the mid-coronal dentin of 50 non-carious human molars using NX3 resin cement with OptiBond XTR or RelyX Ultimate with SBU. µTBS was evaluated after 5,000 thermocycling and analysed with three-way-ANOVA and post-hoc Tukey’s tests (p<0.05). The µTBS was significantly influenced by the type of CAD/CAM material (p<0.0001) surface pre-treatments (p<0.05) and resin cements (p<0.05). Regardless of the pre-treatments and resin cements, bonding of the composite CAD/CAM material to dentin was higher than the resin nano-ceramic material.
Surface replication is a nondestructive evaluation technique applied in examining surfaces’ cracks/wear. This is quite valuable when the surface of interest cannot be further manipulated by cutting or polishing to fit directly under a microscope. Replication by acetate sheets is one of the techniques applied in industrial, metallographic and anthropological wear/examination. Enamel is the outermost protective layer of human teeth and is subjected to mechanical stresses due to the masticatory function; thus, wear is inevitable in human teeth. This relatively inert hard tissue has been reported to possess some properties of both metals and glasses due to its unique delicate microstructure. This study investigated the applicability of replication sheets in registering wear induced features on human enamel surfaces. The sheets replicated wear features successfully with compatibility to use with multiple microscopes. Acetate sheets have a potential in enamel wear replication.
This study investigated the effect of bulk-fill composites on proximal contact tightness (PCT) of composite restorations using different matrix systems. 150/standardized-MO-ivorine cavity preparations were divided into 5 groups; Smart Dentin Replacement (SDR), SonicFill (SF), Tetric EvoCeram Bulk-Fill (TEB), G-ænial Universal Flo (GF) and Tetric EvoCeram (TE). Each group was subdivided into 3 sub-groups (n=10); Dixieland band in Tofflemire retainer, FenderMate and Palodent plus matrix systems. PCT was measured 24 h post-curing using Tooth Pressure Meter. PCT means were calculated and statistically-analyzed using ANOVA and Tukey’s post-hoc test (p<0.05). Means and SD of PCT for Tofflemire subgroup were: 1.75(0.13), 3.21(0.1), 3.06(0.19), 2.49(0.21) and 3.18(0.1) for (SDR), (SF), (TEB), (GF) and (TE), respectively. Using FenderMate, values were: 1.87(0.08), 3.35(0.12), 3.17(0.16), 2.64(0.1) and 3.26(0.11) for (SDR), (SF), (TEB), (GF) and (TE), respectively, while with Palodentplus; 3.16(0.17), 4.23(0.11), 4.1(0.1), 3.46(0.17) and 3.98(0.1) for (SDR), (SF), (TEB), (GF) and (TE), respectively. ANOVA revealed significant differences (p<0.05) between all samples except between (SF), (TEB) and (TE) and also significant difference between Palodentplus and two subgroups. Effect of bulk-fill composites on PCT is material dependent. Separation ring is recommended for proper PCT.
This study evaluates the effects of various agitation methods on the adhesive layer formation of a new HEMA-free universal dentin adhesive. The µTBS of the universal adhesive, G-Premio BOND in the self-etch mode was evaluated using three agitation methods [passive agitation (PA), active agitation (AA), ultrasonic agitation (UA)], with and without aging treatment. Two-way analysis of variance revealed that aging treatment was not a statistically significant factor. Tukey’s HSD test showed significant differences based on the application method, UA>AA>PA. TEM images of the PA group revealed multiple water blisters in the adhesive layers; AA and UA groups presented significantly less or no blisters within the adhesive layers; thus, AA and UA groups exhibited better bonding performance for the HEMA-free universal adhesive. It is assumed that the entrap ped blisters can be reduced with the active application of dentin adhesive, and thus improving the bonding performance.
Tribochemical silica coating (TSC) is commonly used to pretreat zirconia surfaces prior to luting. Although many studies demonstrate an adhesion-promoting effect of TSC on zirconia, its actual interaction mechanism has not been fully elucidated. We therefore characterized the ultrastructure of TSC-treated zirconia and tested shear-bond strength. STEM/EDS disclosed a micro-roughened zirconia surface partially covered with fused Al and Si, while residual unfused silica particles could also still be detected. TSC-treated zirconia having received the solely silane primer exhibited a significantly lower shear-bond strength than zirconia on which the combined 10-MDP/silane primer was applied. SEM fracture analysis revealed residual silica particles on both the zirconia and cement sides. Correlative ultrastructural and chemical surface characterization revealed that TSC deposited an inhomogeneous silica layer on the zirconia surface, which explains why the solely silane coupling agent was less effective than the combined 10-MDP/silane ceramic primer for bonding to zirconia pretreated by TSC.
The objective was to evaluate the fracture resistance properties of maxillary incisors with flared canals restored with computer aided design and computer aided manufacture (CAD/CAM) integrated glass fiber post-and-core. Thirty prepared flared root canals were selected in vitro and restored with CAD/CAM integrated fiber post-and-core (Group A), prefabricated fiber posts (Group B), and cast gold alloy (Group C), respectively. After submitted to fatigue loading, each specimen was subjected to a static loading until fracture. Analysis of variance (ANOVA) tests were used to determine statistical differences. The mean fracture strengths of Groups A and C were significantly higher than those of Group B, whereas no differences were observed between Groups A and C. In addition, reparable fracture modes were mostly observed in Group A while irreparable and catastrophic fractures were mostly found in Groups B and C. These results demonstrate that, in comparison to traditional treatments, CAD/CAM integrated glass fiber post-and-core restoration significantly enhances the fracture resistance of flared root canals.
The relationship between performance of caries detector dyes and solvent molecular weight has been reported, but viscosity has not yet been investigated. Therefore, using extracted human teeth, we compared 6 experimental caries detector dyes with different viscosities to clarify the relationship between dye viscosity and staining performance in sclerotic dentin. Carious dentin started showing dentin staining when stained with caries detector dyes with kinematic viscosity≥263 mm2/s, showed no immunoreactivity for Streptococcus mutans on immunohistochemistry, and contained dentinal tubules free of debris on scanning electron microscopy. Samples stained using a caries detector dye with kinematic viscosity of 332 mm2/s contained calcification product-like debris in the dentinal tubules. These findings suggest that the caries detector dye has a threshold kinematic viscosity between 263 and 332 mm2/s at which sclerotic dentin and tissues beyond are not stained. The caries detector dye appears to control tooth dyeability based on solvent viscosity.
Carbon nanotubes (CNTs) are promising biomaterials in the medical field, especially in tissue engineering of bone. However, the use of CNTs is largely confined by its unfavorable solubility and toxicity. To improve solubility and biocompatibility of CNTs, functionalization has been proven to be an effective strategy. Although various functionalized CNTs have been extensively studied, only few CNTs have the desired qualities. We compared the toxicity of several promising functionalized multi-walled carbon nanotubes (MWCNTs) on rat bone-marrow derived stem cells (BMSCs). Cell experiments showed that while acid oxidation (AO)-MWCNTs and Raw-MWCNTs exhibited significant toxicity on BMSCs, polyethylene glycols (PEG)-MWCNTs and hydroxyapatit (HA)-MWCNTs had favorable biocompatibility and a trivial effect on BMSCs. Possible mechanisms for the cytotoxicity on BMSCs included mitochondrisome and deoxyribonucleic acid damage, increased oxidative stress and damaging of cellular membranes. Our data indicated that PEG-MWCNTs and HA-MWCNTs may be promising materials for bio-related applications.
Polytetrafluoroethylene (PTFE) is chemically stable, non-toxic to humans, highly resistant to heat and chemicals, and has an extremely low coefficient of friction. Therefore, PTFE is used in medical applications. We focused on the physical properties of PTFE in relation to its application as a material for use in prostheses and dental devices/instruments. PTFE exhibited low wear (approximately 1/3 that of bovine tooth, and 1/2 that of type III gold alloy), low dynamic friction (approximately 1/5 that of the other specimens), low hardness (4.8HV1.0), low coloration, and low bacterial adhesion, compared to other specimens except porcelain in wear and coloration test (p<0.01). These results suggest that PTFE could have applications in some prostheses for provisional and/or permanent use, and dental instruments/devices by providing excellent impact absorption, high wear resistance for maintenance of occlusal vertical dimension and original function, and ease of cleaning.
The objective was to evaluate the effect of application of silver diamine fluoride (SDF) on discoloration of demineralized dentin over time. Dentin specimens were divided into four groups according to time of dentin demineralization. A 38% SDF solution was then applied to the dentin surfaces. Half of the specimens were placed in light-proof boxes while the remainder were exposed to light. Both groups were maintained at 37˚C. Color change was determined using a spectrophotometer at different time intervals. SEM/EDS analysis were also undertaken. The 13 h EDTA demineralized group showed the highest values for color change among different time intervals, with the control being the lowest. The light exposed groups showed more color change compared to the unexposed groups. We concluded that the degree of dentin demineralization leads to a significant increase of the rate of dentin color change after application of SDF.
The purpose of this study was to investigate how differences in dental implant and screw materials affected screw loosening. Screws (pure titanium; Ti4S, titanium alloy; TiAS), blocks (Y-TZP; ZrB, pure titanium; Ti4B) and plates (Y-TZP; ZrP), representing abutment screws, implant bodies and superstructures, respectably, were used. Plates were fastened to blocks by screws using a torque of 20 N•cm, and the loosening torque was measured after cyclic loading. Tests was performed on 13 specimens per group, with four groups for loading at the eccentric point (9 mm from screw center) and one group at the centric point (3 mm from screw center). In eccentric point tests, Ti4S screws led to significantly more loosening than TiAS screws (p<0.01). The block material had no effect. For ZrBTi4S, there was no difference in loosening before and after the centric point tests. More loosening occurred for eccentric point than for centric point tests (p<0.05).