Fundamental Properties and Clinical Application of 3D-Printed Bioglass Porcelain Fused to Metal Dental Restoration.

The purpose of this study is to evaluate the mechanical properties and clinical fitness of 3D-printed bioglass porcelain fused to metal (PFM) dental crowns. To evaluate the mechanical properties, tensile strength, Vickers microhardness, shear bond strength, and surface roughness tests of the SLM printed Co-Cr alloy was conducted. A right mandibular 1st molar tooth was prepared for a single dental crown (n = 10). For a three-unit metal crown and bridge, the right mandibular first premolar and first molar were prepared. Bioglass porcelain was fired to fabricate PFM dental restorations. A clinical gap was observed and measured during each of the four times porcelain was fired. A statistical analysis was conducted. The SLM technique showed the largest statistically significant tensile strength and a 0.2% yield strength value. The milling technique had the lowest statistically significant compressive strength value. The shear bond strength and surface roughness showed no statistically significant difference between the fabricated method. There was a statistically significant change in marginal discrepancy according to the porcelain firing step. The casting technique showed the greatest statistically significant margin discrepancy value. The SLM method showed better fitness than the traditional casting method and showed better mechanical properties as a dental material.

Integration of an intraoral scan and a conventional impression for fabricating complete dentures for a patient with flabby tissues.

Inflammatory movable tissues in the maxillary anterior region are the result of excessive stimulation of the anterior alveolar ridge, as the maxillary denture habitually rotates anteriorly and upward during mastication. The pressure required for a functional impression makes it difficult to obtain the accurate anatomy of the inflamed mucosal tissues. An intraoral scanner can be used to record the movable tissues in an immobile state. However, for removable dentures, the oral scanner is limited by the difficulty in evaluating the denture borders or the posterior palatal seal area accurately. The fabrication of a complete denture by combining the use of an oral scanner to capture an anatomic impression without exerting pressure on the maxilla, including the movable tissues, and a traditional functional impression using the closed-mouth technique is described.

Creation of Digital Virtual Patient by Integrating CBCT, Intraoral Scan, 3D Facial Scan: An Approach to Methodology for Integration Accuracy.

ABSTRACT: The purpose of this paper was to introduce a method for creating a digital virtual patient by combining cone-beam computed tomography (CBCT), intraoral scan, and facial scan with a high accuracy of integration. CBCT scan, facial scan, and intraoral scan were obtained from initial visit. The virtual patient was created using the integration of these imaging modalities. Once the virtual patient was generated, digital workflow could be applied to initial patient consultation, diagnosis, treatment planning, virtual tooth setup, virtual treatment simulation, and post-treatment evaluation. integration of digital technology allows clinicians to improve diagnosis and treatment outcome. in addition, it allows for favorable patient communication. This technique eliminates the traditional impression process and complicated laboratory procedures for evaluating patient's occlusion during smile and habitual resting position. Based on this protocol, it is possible to create a digital virtual patient using CBCT, intraoral scan, and facial scan with a high accuracy of integration. it would be helpful for precision diagnosis and accurate treatment as well as favorable communication with patient.

Eggshell membrane as a bioactive agent in polymeric nanotopographic scaffolds for enhanced bone regeneration.

A bone regeneration scaffold is typically designed as a platform to effectively heal a bone defect while preventing soft tissue infiltration. Despite the wide variety of scaffold materials currently available, such as collagen, critical problems in achieving bone regeneration remain, including a rapid absorption period and low tensile strength as well as high costs. Inspired by extracellular matrix protein and topographical cues, we developed a polycaprolactone-based scaffold for bone regeneration using a soluble eggshell membrane protein (SEP) coating and a nanotopography structure for enhancing the physical properties and bioactivity. The scaffold exhibited adequate flexibility and mechanical strength as a biomedical platform for bone regeneration. The highly aligned nanostructures and SEP coating were found to regulate and enhance cell morphology, adhesion, proliferation, and differentiation in vitro. In a calvaria bone defect mouse model, the scaffolds coated with SEP applied to the defect site promoted bone regeneration along the direction of the nanotopography in vivo. These findings demonstrate that bone-inspired nanostructures and SEP coatings have high potential to be applicable in the design and manipulation of scaffolds for bone regeneration.

Bonding Evaluation Between Nanotube by Anodic Oxidation and Machined Dental Titanium Implant in Beagle Dog.

This study is to evaluate the bonding test between nanotube surface and machined dental titanium implant during the clinical procedure in beagle dog. A total of 24 screw-shaped implants (4 mm in diameter and 8.5 mm in length) were used. The implants were classified into 2 groups (n = 12): machined surface (M group) and nano surface which is nanotube formation on the machined surface (MA group). Anodic oxidation was performed at a 20 V for 10 min with 1 M H3PO4 and 1.5 wt% HF solutions. The implant were installed on beagle dog's humerus. After 4 and 12 weeks later, the beagle dog is sacrificed and the implant were removed with torque force. The removed implant was evaluated by SEM and EDX to observe the implant surface and nanotube's deformation. By investigating removed implant surfaces using SEM and EDX, M group was partially covered with bone, and MA groups were completely covered with bone. Nanotube was not shown any deformity. It indicated that nanotube showed good bonding stability with dental titanium implant.

Evaluation of Cure Depth and Geometrical Overgrowth Depending on Zirconia Volume Fraction Using Digital Light Processing.

The optical properties of zirconia photopolymer suspension for DLP (Digital Light Processing) were evaluated. The light source and intensity were set to 395 nm and 30 mW/cm². Experimental groups were divided into 48, 50, 52, 54, 56 and 58 vol% according to the zirconia volume fraction. The cure depth of all groups was at least 47.35 um when cured for 1 sec, which was higher than layer parameter values of the 3D printer. The geometrical overgrowth showed 28.55% at 48 vol% and 36.94% at 58 vol%. As the volume fraction of zirconia increased, the geometrical overgrowth increased and the cure depth reduced.

Shear Bond Strength of Zirconia to Titanium Implant Using Glass Bonding.

This study evaluated the shear bond strength of zirconia to titanium implant components using silica-based glasses and compared the strength with that of implant components bonded using a commercial resin cement. Forty cylindrical zirconia specimens and forty titanium disks (Grade IV) were divided equally into four groups, depending on the adhesive used: three different types of glasses (group G, group GI, group GIB) and a self-adhesive resin cement (group U200), which was used as a control. The shear bond strength was evaluated using a universal testing machine and failure mode was examined by optical microscope. Data was analyzed using One-way ANOVA with p-value <0.05, which was considered statistically significant. The shear bond strength of the three glass groups was significantly higher than that of group U200 (p<0.05). Failure mode in all groups was a combination of adhesive and cohesive modes. Shear bond strength of zirconia to titanium bonded using glasses was higher than that using self-adhesive resin cement.

Biocompatibility Evaluation of Feldspathic Porcelain with Nano-Sized Silver Ion Particles.

The major failure of dental restorations is caused by dental caries by S. mutans. This study evaluated the effect of nanosized silver ions in feldspathic porcelain on cytotoxicity and antimicrobial activity. The control group was feldspathic porcelain (Noritake EX-3, Kuraray Noritake Dental Inc., Japan) that did not contain Ag (silver). The experimental groups were feldspathic porcelain mixed with colloidal solutions of nanosized silver ions in mixtures of 5% 10%, 20%, 30%. Cell activity assays evaluated with osteoblast hFOB 1.19 cells (human Fetal Osteoblastic cell line, ATCC® CRL- 11372™) and antimicrobial activity test used the streptococcus mutans (S. mutans). According to the observations, the addition of Ag to feldspathic porcelain led to increased cell activity and showed excellent antibacterial performance. Especially, the feldspathic porcelain with 30% nanosized Ag ion appeared to have a significant antimicrobial effect, this allows for the possibility of various clinical applications for such material, including use in dental prosthesis and implants.

Evaluation of Acid Etching on Surface Characteristics, Strength and Biological Response of Glass-Infiltrated Zirconia.

This study evaluated the effect of acid etching on surface characteristics, flexural strength and osteoblast cell response of glass-infiltrated zirconia. Zirconia specimens were divided into six groups: untreated zirconia (Z); glass-infiltrated zirconia (ZG); glass-infiltrated and sandblasted zirconia (ZGS); glass-infiltrated, sandblasted and 5 min acid-etched zirconia (ZGS-E5); glassinfiltrated, sandblasted and 15 min acid-etched zirconia (ZGS-E15); glass-infiltrated, sandblasted and 25 min acid-etched zirconia (ZGS-E25). Surface roughness, biaxial flexural strength and MC3T3-E1 cell proliferation were evaluated. When increasing etching time, surface roughness significantly increased while flexural strength decreased. Cell proliferation rate at day 3 on group ZGS-E15 and ZGS-E25 was significantly higher than that of other groups. Surface roughness and flexural strength of glass-infiltrated zirconia can be controlled by adjusting etching time. Rough surface made by acid etching following glass infiltration significantly enhanced osteoblast cell response. Glass infiltration improved strength of zirconia but severe acid etching slightly reduced strength of zirconia.

Novel ß-TCP Coated Titanium Nanofiber Surface for Enhanced Bone Growth.

In this study, we examined the effect of ß-tricalcium phosphate (ß-TCP) coating on alkali-treated CP Grade II titanium surface via RF magnetron sputtering on osteoblast like cell (MC3T3-E1) viability and bone formation in rat tibia. The specimens were divided into three groups; commercially pure titanium (control group), alkali-treated titanium with nanofiber structure (NF group) and ß-TCP coating on alkali-treated titanium with nanofiber structure (TNF group). The surface characteristics of specimens were observed under a field emission scanning electron microscope (FE-SEM), and contact angle was measured. The cell viability was assessed in vitro after 1 day, 3 days and 7 days. Implants of 2.0 mm diameter and 5.0 mm length were inserted into the tibia of rats. After 4 wks, the histomorphometric analysis was performed. Group NF and group TNF showed improved hydrophilicity of Ti. Group TNF showed significantly higher cell viability (P < 0.05) after 7 days. The bone to implant contact (BIC) ratio of the control group, NF group, and TNF group were 32.3%, 35.5%, and 63.9%, respectively. The study results suggested that ß-TCP coated alkali-treated titanium surface via RF magnetron sputtering might be effective in implant dentistry due to enhanced hydrophilicity, improved cell response, and better osseointegration.

Hydroxyapatite Coating on TiO2 Nanotube by Sol-Gel Method for Implant Applications.

The aim of this study was to determine the effect of hydroxyapatite (HA) coating on titanium dioxide (TiO2) nanotube by sol-gel process on viability of osteoblast like cell (MC3T3-E1) and bone formation in rat tibia. Specimens were divided into three groups including commercially pure titanium (control group), TiO2 nanotubes (group N), and HA coated TiO2 nanotubes (group HN). Surface characteristics were determined using field emission scanning electron microscope (FE-SEM; S-4700, Hitachi, Japan) and contact angles were measured. Cell viability was investigated in vitro after 1 day, 3 days, and 7 days of incubation. Implants (2.0 mm in diameter and 5.0 mm in length) were inserted into the tibia of rats. After 4 weeks, histomorphometric analysis was performed. Both N and HN groups showed enhanced hydrophilicity compared to control group. After 7 days of implantation, group HN showed higher cell viability with marginal significance (0.05 < P < 0.1). Bone to implant contact (BIC) ratio in the control group, group N, and group HN were 32.5%, 33.1%, and 43.8%, respectively. Results of this study showed that HA coated TiO2 nanotube using sol-gel process could be used to enhance hydrophilicity and improve osseointegration of dental implant surface.

Evaluation of the Fitness of Glass-Infiltrated Zirconia Core in Maxillary Central Incisor.

The purpose of this study was to evaluate the fitness of zirconia cores according to the amount and treated surface of glass infiltration. A maxillary right central incisor customized abutment was milled to have a 6° slope and a 1 mm deep chamfer margin and was manufactured in an intaglio mold using silicone impression material. Fifty-six stone dies were produced by injecting high strength dental stone into a mold and then zirconia cores were milled with CAD/CAM systems. The control group (Control) used non glass-infiltrated zirconia, and the experiment group was divided by one with the glass and distilled water ratio of 1:300 and the other with the ratio of 1:100. Each group was divided into subgroups by glasstreated surface: external surface infiltration, internal surface infiltration, and both surface infiltration. The zirconia cores sintered after glass infiltration were attached to the stone dies and then cut. Afterwards, the absolute marginal discrepancies and internal gaps of the buccal and lingual sides were measured. The buccal absolute marginal discrepancies and lingual internal gaps were influenced by the glass infiltration amount (p < 0.05); while fitness of zirconia core were not affected by the glasstreated surface (p > 0.05). As a result of the above experiments, the glass-infiltrated zirconia cores showed a clinically acceptable fitness, which is within 120 µm. This means that glass infiltration can be clinically used.

Effects on Antibacterial Activity and Osteoblast Viability of Non-Thermal Atmospheric Pressure Plasma and Heat Treatments of TiO2 Nanotubes.

The aim of this study was to evaluate the antibacterial activity against Porphyromonas gingivalis and osteoblast viability of heat and plasma treatment of TiO2 nanotubes. Specimens were divided into four groups: the Ti (polished titanium), Nano (TiO2 nanotube), NH 300 (heat treated at 300 °C on TiO2 nanotube) and NH 400 (heat treated at 400 °C on TiO2 nanotube) groups. Antibacterial activity and osteoblast viability were evaluated in the four groups according to plasma treatment. Surface adhesion of Porphyromonas gingivalis was evaluated by crystal violet assay. Osteoblast viability was examined by XTT assay. Adhesion of Porphyromonas gingivalis was significantly decreased in the Ti group, Nano group and NH 300 group after plasma treatment (P < 0.05). Osteoblast viability was increased in the NH 400 group in comparison to the Ti group before plasma treatment (P < 0.05). Within the limitations of this study, plasma treatment was found to reduce the adhesion of P. gingivalis but had no influence on osteoblast activation.

Effect on Adhesion of Porphyromonas gingivalis by Titanium Nitride Sputter Coating or Plasma Nitriding of Titanium.

Porphyromonas gingivalis (P. gingivalis) is one of main bacteria that adheres to the surface of dental implants and causes peri-implantitis. The purpose of this study was to observe the surface characteristics of titanium processed with either titanium nitride (TiN) sputter coating or plasma nitriding and to evaluate the subsequent adhesion of P. gingivalis. Specimens were divided into three groups: commercially pure (CP) titanium (control group), TiN sputter­coated titanium (group S), and plasma-nitrided titanium (group P). Surface characteristics such as roughness, morphology, and the formation of a thin TiN film or a nitriding layer were assessed. Adhesion of P. gingivalis in the three groups was determined by means of the crystal violet staining assay, and results were compared with one-way ANOVA, with post hoc comparison using Tukey's test (α = 0.05). Surface roughness values for the control group, group S, and group P were 0.08±0.02 µm, 0.19±0.04 µm, and 0.13±0.02 µm, respectively. In group S, the TiN layer was 1.36±0.1 µm thick, and nitrogen was detected on the surface of the specimens in group P, confirming formation of a nitrided layer. The level of adhesion in group P was significantly higher than that in the control group and in group S (p < 0.05), but there was no significant difference between the control group and group S. Within the limitations of this study, TiN sputter coating did not affect adhesion of P. gingivalis on the titanium surface, whereas adhesion was increased on the plasma-nitrided titanium surface.

The Effect of Glass Layer Thickness on the Shear Bond Strength Between Glass Infiltrated Zirconia and Veneering Porcelain.

This study was to investigate the various glass thicknesses on the shear bond strength between zirconia and veneering porcelain. The zirconia specimens were classified into 5 groups (n = 12). For the control group, the Y-TZP disk was sintered (G0). For the test group, the presintered zirconia disks were spin coated with different W/P ratio glass compositions. The glass thickness on the zirconia was 1 µm (G1), 4 µm (G4), 10 µm (G10), and 40 µm (G40), respectively. All specimens were build-up veneering porcelain and fired. The shear bond strength (SBS) was tested in a universal testing machine (crosshead speed = 0.5 mm/min). As the thickness of the glass decreased, the shear bond strength increased. The G1 group showed significantly higher than the control group (G0) (P < 0.05). The results suggest that the thickness of glass coating on the zirconia structure needs to be made thin for better bonding strength with veneering porcelain.

Surface Characteristics of Bioactive Glass-Infiltrated Zirconia with Different Hydrofluoric Acid Etching Conditions.

The purpose of this study was to examine the surface characteristics of bioactive glass-infiltrated zirconia specimens that underwent different hydrofluoric acid (HF) etching conditions. Specimens were classified into the following six groups: Zirconia, Zirliner, Porcelain, Bioactive glass A1, Bioactive glass A2, and Bioactive glass A3. Zirliner and porcelain were applied to fully sintered zirconia followed by heat treatment. Bioactive glass was infiltrated into presintered zirconia using a spin coating method followed by complete sintering. All the specimens were acid-etched with 10% or 20% HF, and surface roughness was measured using a profiler. The surface roughness of the zirconia group was not affected by the etching time or the concentration of the acid. The roughness of the three bioactive glass groups (A1, A2, and A3) was slightly increased up until 10 minutes of etching. After 1 hour of etching, the roughness was considerably increased. The infiltrated bioactive glass and acid etching did not affect the adhesion and proliferation of osteoblasts. This study confirmed that surface roughness was affected by the infiltration material, etching time, and acid concentration. For implant surfaces, it is expected that the use of etched bioactive glass-infiltrated zirconia with micro-topographies will be similar to that of machined or sand-blasted/acid-etched (SLA) titanium.

Histological Evaluation of Nano-Micro Titanium Implant Surface Treatment in Beagle Humerus.

The objective of this study was to investigate the effects of nano-micro titanium implant surface using histology in beagle dogs. A total of 48 screw-shaped implants (Megagen, Daegu, Korea) which dimensions were 4 mm in diameter and 8.5 mm in length, were used. The implants were classified into 4 groups (n = 12): machined surface (M group), RBM (Resorbable Blasting Media) surface (R group), nano surface which is nanotube formation on the machined surface (MA group) and nano-micro surface which is nanotube formation on the RBM surface (RA group). Anodic oxidation was performed at a constant voltage of 20 V for 10 min using a DC power supply (Fine Power F-3005; SG EMD, Anyang, Korea). The bone blocks were investigated using histology. There was no inflammation around implants, and new bone formation was shown along with the nano-micro titanium implant surfaces. The amount of bone formation was increased depending on time comparing 4 weeks and 12 weeks. At 12 weeks, lamellar bone was more formed along with the nano-micro titanium implant surfaces than 4 weeks. It indicated that nano-micro surface showed good result in terms of osseointegration.

Evaluation of Osteoblast-Like Cell Viability and Differentiation on the Gly-Arg-Gly-Asp-Ser Peptide Immobilized Titanium Dioxide Nanotube via Chemical Grafting.

This study examined the effect of the immobilization of the Gly-Arg-Gly-Asp-Ser (GRGDS) peptide on titanium dioxide (TiO2) nanotube via chemical grafting on osteoblast-like cell (MG-63) viability and differentiation. The specimens were divided into two groups; TiO2 nanotubes and GRGDS-immobilized TiO2 nanotubes. The surface characteristics of GRGDS-immobilized TiO2 nanotubes were observed by using X-ray photoelectron spectroscopy (XPS) and a field emission scanning electron microscope (FE-SEM). The morphology of cells on specimens was observed by FE-SEM after 2 hr and 24 hr. The level of cell viability was investigated via a tetrazolium (XTT) assay after 2 and 4 days. Alkaline phosphatase (ALP) activity was evaluated to measure the cell differentiation after 4 and 7 days. The presence of nitrogen up-regulation or C==O carbons con- firmed that TiO2 nanotubes were immobilized with GRGDS peptides. Cell adhesion was enhanced on the GRGDS-immobilized TiO2 nanotubes compared to TiO2 nanotubes. Furthermore, significantly increased cell spreading and proliferation were observed with the cells grown on GRGDS-immobilized TiO2 nanotubes (P < .05). However, there was no significant difference in ALP activity between GRGDS-immobilized TiO2 nanotubes and TiO2 nanotubes. These results suggest that the GRGDS-immobilized TiO2 nanotubes might be effective in improving the osseointegration of dental implants.

Evaluation of Antibacterial Activity of Titanium Surface Modified by PVD/PACVD Process.

The aim of this study was to evaluate the response of Streptococcus mutans (S. mutans) via crystal violet staining assay on titanium surface modified by physical vapor deposition/plasma assisted chemical vapor deposition process. Specimens were divided into the following three groups: polished titanium (control group), titanium modified by DC magnetron sputtering (group TiN-Ti), and titanium modified by plasma nitriding (group N-Ti). Surface characteristics of specimens were observed by using nanosurface 3D optical profiler and field emission scanning electron microscope. Group TiN-Ti showed TiN layer of 1.2 microm in thickness. Group N-Ti was identified as plasma nitriding with X-ray photoelectron spectroscopy. Roughness average (Ra) of all specimens had values < or = 0.2 microm (the threshold Ra), which had no effect on bacterial adhesion. No significant difference of S. mutans adhesion was found between the surfaces of control, TiN-Ti, and N-Ti (P > 0.05). Within the process condition of this study, modified titanium surfaces by DC magnetron sputtering and plasma nitriding did not influence the adhesion of S. mutans.

Complete-mouth rehabilitation using a 3D printing technique and the CAD/CAM double scanning method: A clinical report.

According to evolving computer-aided design/computer-aided manufacturing (CAD/CAM) technology, ceramic materials such as zirconia can be used to create fixed dental prostheses for partial removable dental prostheses. Since 3D printing technology was introduced a few years ago, dental applications of this technique have gradually increased. This clinical report presents a complete-mouth rehabilitation using 3D printing and the CAD/CAM double-scanning method.