Biofabricated poly (γ-glutamic acid) bio-ink reinforced with calcium silicate exhibiting superior mechanical properties and biocompatibility for bone regeneration.

Background/purpose: The modification in 3D hydrogels, tissue engineering, and biomaterials science has enabled us to fabricate novel substitutes for bone regeneration. This study aimed to combine different biomaterials by 3D technique to fabricate a promising all-rounded hydrogel for bone regeneration. Materials and methods: In this study, glycidyl methacrylate (GMA)-modified poly γ-glutamic acid (γ-PGA-GMA) hydrogels with calcium silicate (CS) hydrogel of different concentrations were fabricated by a 3D printing technique, and their biocompatibility and capability in bone regeneration were also evaluated. Results: The results showed that CS γ-PGA-GMA could be successfully fabricated, and the presence of CS enhanced the rheological and mechanical properties of γ-PGA-GMA hydrogels, thus making them more adept at 3D printing and implantations. SEM images of the surface structure showed that higher CS concentrations (5% and 10%) contributed to denser surface architectures, thus achieving improved cellular adhesion and stem cell proliferation. Furthermore, higher concentrations of CS resulted in elevated expressions of osteogenic-related markers such as alkaline phosphatase (ALP) and osteocalcin (OC), as well as enhanced calcium deposition represented by the increased Alizarin Red S staining. In vivo studies referring to critical defects of rabbit femur further showed that the existence of hydrogels alone was able to induce partial bone regeneration, demonstrated by the results from quantitative and qualitative analysis of micro-CT scans. However, CS alterations caused significant increases in bone regeneration, as indicated by micro-CT and histological staining. Conclusion: These results robustly suggest combining different biomaterials is crucial to producing a well-rounded hydrogel for tissue regeneration. We hope this study could be applied as a platform for others to brainstorm potential out-of-the-box solutions, contributing to developing high-potential biomaterials for bone regeneration.

Oral Lactobacillus zeae exacerbates the pathological manifestation of periodontitis in a mouse model.

INTRODUCTION: The worldwide prevalence of periodontitis is considerably high, and its pathogenic mechanisms must be investigated and understood in order to improve clinical treatment outcomes and reduce the disease prevalence and burden. The exacerbation of the host immune system induced by oral microbial dysbiosis and the subsequent tissue destruction are the hallmarks of the periodontitis. However, the oral bacteria involved in periodontitis are not fully understood. We used the Oxford Nanopore Technologies (ONT) sequencing system to analyze metagenomic information in subgingival dental plaque from periodontitis and non-periodontitis patients. The number of Lactobacillus zeae (L. zeae) in the periodontitis patients was 17.55-fold higher than in the non-periodontitis patients, suggesting that L. zeae is a novel periodontitis-associated pathogen. Although several Lactobacillus species are used in vivo as probiotics to treat periodontitis and compete with Porphyromonas gingivalis (P. gingivalis), the roles of L. zeae in periodontitis progression, and the relationship between L. zeae and P. gingivalis needs to be investigated. METHODS: Both L. zeae and P. gingivalis were inoculated in the ligature-implant site of periodontitis mice. We collected mouse gingival crevicular fluid to analyze inflammatory cytokine secretion using a multiplex assay. Intact or sliced mouse maxilla tissue was used for micro-computed tomography analysis or hematoxylin and eosin staining, immunohistochemistry, and tartrate-resistant acid phosphatase staining to evaluate alveolar bone loss, neutrophil infiltration, and osteoclast activation, respectively. RESULTS: We observed that L. zeae competed with P. gingivalis, and it increased inflammatory cytokine secretion at the ligature-implant site. Similar to P. gingivalis, L. zeae promoted ligature-induced neutrophile infiltration, osteoclast activation, and alveolar bone loss. DISCUSSION: We, therefore, concluded that L. zeae accelerated the progression of periodontitis in the ligature-induced periodontitis mouse model.

Comparison of the physical, thermal, and biological effects on implant bone site when using either zirconia or stainless-steel drill for implant bone site preparation.

BACKGROUND/PURPOSE: Zirconia has been a popular material in dental implantology with good biocompatibility. But few research focused on its application in implant drills. This study aimed to investigate the physical, thermal, and biological effects on using the zirconia and stainless-steel drills for implant bone site preparation. METHODS: We performed a series of experiments to evaluate the physical wearing properties of zirconia and stainless-steel drills of identical diameter and similar shape. During the implant site preparation thermal test, we subjected both drills onto a resin-embedded bone, utilizing a thermal couple device without irrigation. Moreover, we conducted a cell study by collecting bone cells in vivo while preparing the implant site with both tested drills. The cell activity was evaluated through cell proliferation colorimetric analysis (XTT) and alkaline phosphatase (ALP) activity measurements. RESULTS: The zirconia drill outperforms the stainless-steel drill in terms of requiring less force, maintaining stability over repeated cutting tests, and generating lower temperatures during drilling (stainless-steel drill: 45.48 ± 1.31 °C; zirconia-coated drill: 32.98 ± 1.21 °C, P = 0.000247). Meanwhile, both types of drills show similar results in XTT colorimetric analysis and ALP activity test. CONCLUSION: The thermal effect study is more favorable for using the zirconia drill than the stainless-steel drill for bone preparation. Cytological analysis indicate that the zirconia drill produces a similar impact on bone cells activity as the stainless-steel drill. Therefore, we conclude that the zirconia drills offer a good cutting effect similar to currently available stainless-steel drills in various aspects.

Reliability of clinical examination methods for postoperative pain after primary root canal treatment.

Background/purpose: Clinical test results may have lower reliability due to the varying range of test stimulation or patient subjectiveness. This study aimed to verify a reliable clinical test method by comparing pain intensity levels of a tooth at rest, during function, and after the clinical tests of percussion and chewing. Materials and methods: A total of 36 asymptomatic necrotic teeth that required root canal treatment, one in each patient, were included. All treatment procedures were performed in a single visit by an experienced endodontist. Patients were asked to mark their pain levels on a vertical visual analog scale (VAS) while the relevant tooth was at rest and during function 24 h after the treatment. In addition, patients marked their pain levels after the clinical tests of percussion and chewing. Finally, the pain levels were compared using Pearson's correlation for the reliability of the test methods at a significance level of 95%. Results: The postoperative pain levels measured during the clinical tests and functions were significantly higher than the pain levels at rest (P < 0.05). The pain levels after percussion tests were significantly higher than that during the function and chewing tests (P < 0.05). Pain intensity during the function was simulated with a higher correlation when using the chewing strip method rather than the percussion method. Conclusion: The bite test using the chewing strips as a pain intensity assessment can mimic the actual postoperative pain experience, whereas the percussion test fails to provide the accuracy of this pain experience.

Third-generation sequencing-selected Scardovia wiggsiae promotes periodontitis progression in mice.

BACKGROUNDS: Periodontitis is an oral-bacteria-directed disease that occurs worldwide. Currently, periodontal pathogens are mostly determined using traditional culture techniques, next-generation sequencing, and microbiological screening system. In addition to the well-known and cultivatable periodontal bacteria, we aimed to discover a novel periodontal pathogen by using DNA sequencing and investigate its role in the progression of periodontitis. OBJECTIVE: This study identified pathogens from subgingival dental plaque in patients with periodontitis by using the Oxford Nanopore Technology (ONT) third-generation sequencing system and validated the impact of selected pathogen in periodontitis progression by ligature-implanted mice. METHODS: Twenty-five patients with periodontitis and 25 healthy controls were recruited in this study. Subgingival plaque samples were collected for metagenomic analysis. The ONT third-generation sequencing system was used to confirm the dominant bacteria. A mouse model with ligature implantation and bacterial injection verified the pathogenesis of periodontitis. Neutrophil infiltration and osteoclast activity were evaluated using immunohistochemistry and tartrate-resistant acid phosphatase assays in periodontal tissue. Gingival inflammation was evaluated using pro-inflammatory cytokines in gingival crevicular fluids. Alveolar bone destruction in the mice was evaluated using micro-computed tomography and hematoxylin and eosin staining. RESULTS: Scardovia wiggsiae (S. wiggsiae) was dominant in the subgingival plaque of the patients with periodontitis. S. wiggsiae significantly deteriorated ligature-induced neutrophil infiltration, osteoclast activation, alveolar bone destruction, and the secretion of interleukin-6, monocyte chemoattractant protein-1, and tumor necrosis factor-α in the mouse model. CONCLUSION: Our metagenome results suggested that S. wiggsiae is a dominant flora in patients with periodontitis. In mice, the induction of neutrophil infiltration, proinflammatory cytokine secretion, osteoclast activation, and alveolar bone destruction further verified the pathogenic role of S. wiggsiae in the progress of periodontitis. Future studies investigating the metabolic interactions between S. wiggsiae and other periodontopathic bacteria are warranted.

Development of antibacterial composite resin containing chitosan/fluoride microparticles as pit and fissure sealant to prevent caries.

OBJECTIVE: Develop a fissure sealant containing chitosan/fluoride microparticles (C/F) with antibacterial, fluoride release and recharge ability. MATERIALS AND METHODS: Chitosan/fluoride microparticles were synthesized and added to Bis-GMA as C/F. The experimental group comprised 0%, 2%, 4% C/F, with ClinproTM fissure sealant as control. Antibacterial activity was detected by Alamar Blue assay and colony-forming units (CFU). Biocompatibility was determined by WST-1 and LDH test. Curing depth, flowability, tensile strength and flexural strength were measured according to the ISO standard; microhardness by Vickers hardness test. Fluoride release and recharge were recorded through ionic chromatography. Statistical analysis was performed with an independent t-test, one-way and two-way ANOVA. P values less than 0.05 were considered significant. RESULTS: 2% and 4% C/F showed antibacterial ability with CFU ratios decreasing to 10% and 25% respectively (P < 0.01). Nonetheless, 4% C/F was concerned because biocompatibility revealed cytotoxicity compared to medium (P < 0.001). 2% C/F had superior mechanical properties to ClinproTM fissure sealant in terms of curing depth (P < 0.001), microhardness and tensile strength (P < 0.01). It had good fluoride release and recharge ability (P = 0.67). CONCLUSIONS: 2% C/F could be an antibacterial sealant with good mechanical strength, fluoride release and recharge ability.

In vitro evaluation of injectable Tideglusib-loaded hyaluronic acid hydrogels incorporated with Rg1-loaded chitosan microspheres for vital pulp regeneration.

Injectable systems receive attention in endodontics due to the complicated and irregular anatomical structure of root canals. Here, injectable Tideglusib (Td)-loaded hyaluronic acid hydrogels (HAH) incorporated with Rg1-loaded chitosan microspheres (CSM) were developed for vital pulp regeneration, providing release of Td and Rg1 to trigger odontoblastic differentiation of human dental pulp stem cells (DPSC) by Td and vascularization of pulp by Rg1. The optimal concentrations were determined as 90 nM and 50 µg/mL for Td and Rg1, and loaded in HA and CSM in HAH, respectively. Odontogenic (COL1A1, ALP, OCN, Axin-2, DSPP, and DMP1) and angiogenic (VEGFA, VEGFR2, and eNOS) differentiation of DPSC cultured in the presence of hydrogels was shown at gene expression level. Our results suggest that our injectable hydrogel formulation has potential to improve strategies for vital pulp regeneration. In vivo evaluations are needed to test the feasibility and potential of these hydrogels for vital pulp regeneration.

The neutrophil elastase-upregulated placenta growth factor promotes the pathogenesis and progression of periodontal disease.

BACKGROUND: Periodontal disease is a chronic inflammatory disease. Given its high prevalence, especially in aging population, the detailed mechanisms about pathogenesis of periodontal disease are important issues for study. Neutrophil firstly infiltrates to periodontal disease-associated pathogen loci and amplifies the inflammatory response for host defense. However, excessive neutrophil-secreted neutrophil elastase (NE) damages the affected gingival. In lung and esophageal epithelium, NE had been proved to upregulate several growth factors including placenta growth factor (PGF). PGF is an angiogenic factor with proinflammatory properties, which mediates the progression of inflammatory disease. Therefore, we hypothesize excessive NE upregulates PGF and participates in the pathogenesis and progression of periodontal disease. METHODS: In gingival epithelial cells (GEC), growth factors array demonstrated NE-increased growth factors and further be corroborated by Western blot assay and ELISA. The GEC inflammation was evaluated by ELISA. In mice, the immunohistochemistry results demonstrated ligature implantation-induced neutrophil infiltration and growth factor upregulation. By multiplex assay, the ligature-induced proinflammatory cytokines level in gingival crevicular fluid (GCF) were evaluated. Finally, alveolar bone absorption was analyzed by micro-CT images and H & E staining. RESULTS: NE upregulated PGF expression and secretion in GEC. PGF promoted GEC to secret IL-1ß, IL-6, and TNF-α in GCF In periodontal disease animal model, ligature implantation triggered NE infiltration and PGF expression. Blockade of PGF attenuated the ligature implantation-induced IL-1ß, IL-6, TNF-α and MIP-2 secretion and ameliorated the alveolar bone loss in mice. CONCLUSION: In conclusion, the NE-induced PGF triggers gingival epithelium inflammation and promotes the pathogenesis and progression of periodontal disease.

Mechanical assessment and odontogenic behavior of a 3D-printed mesoporous calcium silicate/calcium sulfate/poly-ε-caprolactone composite scaffold.

BACKGROUND/PURPOSE: Tissue engineering in dentistry has fundamentally changed the way endodontists assess treatment options. Our previous study found that quercetin-contained mesoporous calcium silicate/calcium sulfate (MSCSQ) could induce hard tissue defect region regeneration. This study focused on whether the MSCSQ scaffold could also be effective in regulating odontogenesis and dentin regeneration. METHODS: In this study, we fabricated MSCSQ composite scaffolds using the 3D printing technique. The characteristics of the MSCSQ scaffold were examined by scanning electron microscope (SEM), and mechanical properties were also assessed. In addition, we evaluated the cell viability, cell proliferation, odontogenic-related protein expression, and mineralization behavior of human dental pulp stem cells (hDPSCs) cultured on different scaffolds. RESULTS: We found the precipitation of spherical-apatite on the scaffold surface rapidly in short periods. The in-vitro results for cell behavior revealed that hDPSCs with an MSCSQ scaffold were significantly higher in cell viability as followed time points. In addition, the specific makers of odontogenesis, such as DSPP and DMP-1 proteins, were induced obviously after culturing the hDPSCs on the MSCSQ scaffold. CONCLUSION: Our results demonstrated that MSCSQ scaffolds could enhance physicochemical and biological behaviors compared to mesoporous calcium silicate/calcium sulfate (MSCS) scaffolds. In addition, MSCSQ scaffolds also enhanced odontogenic and immuno-suppressive properties compared to MSCS scaffolds. These results indicated that MSCSQ scaffolds could be considered a potential bioscaffold for clinical applications and dentin regeneration.

3D-Printed Ginsenoside Rb1-Loaded Mesoporous Calcium Silicate/Calcium Sulfate Scaffolds for Inflammation Inhibition and Bone Regeneration.

Bone defects are commonly found in the elderly and athletic population due to systemic diseases such as osteoporosis and trauma. Bone scaffolds have since been developed to enhance bone regeneration by acting as a biological extracellular scaffold for cells. The main advantage of a bone scaffold lies in its ability to provide various degrees of structural support and growth factors for cellular activities. Therefore, we designed a 3D porous scaffold that can not only provide sufficient mechanical properties but also carry drugs and promote cell viability. Ginsenoside Rb1 (GR) is an extract from panax ginseng, which has been used for bone regeneration and repair since ancient Chinese history. In this study, we fabricated scaffolds using various concentrations of GR with mesoporous calcium silicate/calcium sulfate (MSCS) and investigated the scaffold's physical and chemical characteristic properties. PrestoBlue, F-actin staining, and ELISA were used to demonstrate the effect of the GR-contained MSCS scaffold on cell proliferation, morphology, and expression of the specific osteogenic-related protein of human dental pulp stem cells (hDPSCs). According to our data, hDPSCs cultivated in GR-contained MSCS scaffold had preferable abilities of proliferation and higher expression of the osteogenic-related protein and could effectively inhibit inflammation. Finally, in vivo performance was assessed using histological results that revealed the GR-contained MSCS scaffolds were able to further achieve more effective hard tissue regeneration than has been the case in the past. Taken together, this study demonstrated that a GR-containing MSCS 3D scaffold could be used as a potential alternative for future bone tissue engineering studies and has good potential for clinical use.

Nitrogen-Doped Titanium Dioxide Mixed with Calcium Peroxide and Methylcellulose for Dental Bleaching under Visible Light Activation.

The available tooth whitening products in the market contain high concentrations of hydrogen peroxide (H2O2) as an active ingredient. Therefore, in order to curb the high H2O2 concentration and instability of liquid H2O2, this study evaluated the efficacy and cytotoxicity of the bleaching gel composed of 10% calcium peroxide (CaO2) and visible-light-activating nitrogen-doped titanium dioxide (N-TiO2) with methyl cellulose as a thickener. Extracted bovine teeth were discolored using coffee and black tea stain solution and were divided into two groups (n = 6). Bleaching was performed thrice on each tooth specimen in both the groups, with one minute of visible light irradiation during each bleaching time. The CIELAB L*a*b* values were measured pre- and post-bleaching. The N-TiO2 calcinated at 350 °C demonstrated a shift towards the visible light region by narrowing the band gap energy from 3.23 eV to 2.85 eV. The brightness (ΔL) and color difference (ΔE) increased as bleaching progressed each time in both the groups. ANOVA results showed that the number of bleaching significantly affected ΔE (p < 0.05). The formulated bleaching gel exhibits good biocompatibility and non-toxicity upon exposure to 3T3 cells. Our findings showed that CaO2-based bleaching gel at neutral pH could be a stable, safe, and effective substitute for tooth whitening products currently available in the market.

Vitamin B12 deficiency and anemia in 140 Taiwanese female lacto-vegetarians.

BACKGROUND/PURPOSE: Lacto-vegetarians (LVs) tend to have vitamin B12 deficiency (B12D). This study assessed whether 140 female LVs, including 16 B12D/LVs and 124 non-B12D/LVs, had significantly higher frequencies of microcytosis, macrocytosis, and of blood hemoglobin (Hb), red blood cell (RBC), and serum vitamin B12 deficiencies than 140 healthy control subjects (HCSs). METHODS: The complete blood count and serum vitamin B12 level in 140 female LVs and 140 female HCSs were measured and compared. RESULTS: We found that 8.6%, 4.3%, 22.9%, 20.0%, and 11.4% of 140 LVs had microcytosis, macrocytosis, and blood Hb, RBC, and serum vitamin B12 deficiencies, respectively. The 140 LVs, 16 B12D/LVs, and 124 non-B12D/LVs had significantly higher frequencies of microcytosis as well as blood Hb and RBC deficiencies than 140 HCSs (all P-values < 0.005). Moreover, both 140 LVs and 124 non-B12D/LVs had significantly higher frequencies of macrocytosis than 140 HCSs. In this study, 32 (22.9%) of 140 LVs including 5 B12D/LVs and 27 non-B12D/LVs had anemia. Of the 5 anemic B12D/LVs, three had normocytic anemia, one had iron deficiency anemia (IDA), and one had thalassemia trait-induced anemia. Moreover, of the 27 anemic non-B12D/LVs, 18 had normocytic anemia, one had IDA, one had thalassemia trait-induced anemia, and 7 had microcytic anemia other than IDA and thalassemia trait-induced anemia. CONCLUSION: LVs have significantly higher frequencies of microcytosis, macrocytosis, blood Hb, RBC, and serum vitamin B12 deficiencies than HCSs. Normocytic and microcytic anemias are the two most common types of anemia in our LVs.

Incorporation of Calcium Sulfate Dihydrate into a Mesoporous Calcium Silicate/Poly-ε-Caprolactone Scaffold to Regulate the Release of Bone Morphogenetic Protein-2 and Accelerate Bone Regeneration.

Tissue engineering and scaffolds play an important role in tissue regeneration by supporting cell adhesion, proliferation, and differentiation. The design of a scaffold is critical in determining its feasibility, and it is critical to note that each tissue is unique in terms of its morphology and composition. However, calcium-silicate-based scaffolds are undegradable, which severely limits their application in bone regeneration. In this study, we developed a biodegradable mesoporous calcium silicate (MS)/calcium sulfate (CS)/poly-ε-caprolactone (PCL) composite and fabricated a composite scaffold with 3D printing technologies. In addition, we were able to load bone morphogenetic protein-2 (BMP-2) into MS powder via a one-step immersion procedure. The results demonstrated that the MS/CS scaffold gradually degraded within 3 months. More importantly, the scaffold exhibited a gradual release of BMP-2 throughout the test period. The adhesion and proliferation of human dental pulp stem cells on the MS/CS/BMP-2 (MS/CS/B) scaffold were significantly greater than that on the MS/CS scaffold. It was also found that cells cultured on the MS/CS/B scaffold had significantly higher levels of alkaline phosphatase activity and angiogenic-related protein expression. The MS/CS/B scaffold promoted the growth of new blood vessels and bone regeneration within 4 weeks of implantation in rabbits with induced critical-sized femoral defects. Therefore, it is hypothesized that the 3D-printed MS/CS/B scaffold can act both as a conventional BMP-2 delivery system and as an ideal osteoinductive biomaterial for bone regeneration.

Differences in the biomechanical behaviors of natural teeth and dental implants.

OBJECTIVE: The lack of a PDL, which acts as an energy absorber, is a contributor to implants' early failure; however, these discrepancies are not well understood because of limited in vivo research. This study investigated the discrepancy in biomechanical behaviors between natural teeth and dental implants by detecting micro-movements in vivo. METHODS: We designed a device that could measure precisely mechanical behaviors such as creep, stress relaxation, and hysteresis by using load-control displacement on teeth and implants. We also compared energy dissipation between natural teeth and dental implants by subtracting the area of the hysteresis loop of natural teeth from that of dental implants. RESULTS: Biphasic curves with an initial phase of rapid response and a subsequent phase of slow response were confirmed in creep and stress relaxation curves for the load-time relationship in natural teeth. By contrast, the behavior of creep or stress relaxation was less prominent when the dental implants were tested. We observed that the periodontal ligament under an axial intrusive load of 300g in a loading rate 3g/s could dissipate the energy of 7.35±1.18×10-2 mJ, approximately 50 times that of the dental implants (1.47±1.22×10-3) with statistically significant (p<0.05). SIGNIFICANCE: We confirmed natural teeth could achieve greater energy dissipation compared to dental implants, which owe to that natural teeth exhibited fluid and viscoelastic properties.

The synergistic effects of quercetin-containing 3D-printed mesoporous calcium silicate/calcium sulfate/poly-ε-caprolactone scaffolds for the promotion of osteogenesis in mesenchymal stem cells.

BACKGROUND/PURPOSE: Several growth factors were proven to be effective in the treatment of bone defects and fractures and thus have great potential for bone regeneration applications. However, it needs low-temperature storage and transportation. This study aimed to investigate the herbal extract quercetin, a candidate for natural flavonoid compounds that have been reported to be involved in regulating inflammation and improving immunity and health. METHODS: In this study, we prepared quercetin (Q)/mesoporous calcium silicate calcium sulfate (MSCS)/polycaprolactone (PCL) composite scaffolds using the 3D printing technique, where we immersed it in simulated body fluid (SBF) solution and soaked it for up to 60 days. The characteristics of quercetin scaffold were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), immunofluorescence, and Alizarin Red S staining. RESULTS: We found precipitation of apatite on the surface of the scaffold. The in vitro results for cell proliferation, cytotoxicity, and immunofluorescence staining revealed that Wharton's jelly mesenchymal stem cells (WJMSCs) with a 2% quercetin (Q2) scaffold were significantly higher in number than with 1% quercetin (Q1) and MSCS scaffolds. The phalloidin staining of cell skeletons on the surface of Q2 revealed powerful cell-to-cell adhesion and high expression of green fluorescence. The Q2 scaffold also had the highest calcium deposit levels based on Alizarin Red S staining in all scaffolds. This indicated that quercetin was able to induce cell growth and mitosis, echoing the previous preliminary results. CONCLUSION: Our initial results indicate that this natural herbal extract can be a good bone-based gene substitution for bone regeneration.

Comparing image qualities of dental cone-beam computed tomography with different scanning parameters for detecting root canals.

BACKGROUND/PURPOSE: Cone-beam computed tomography (CBCT) is a useful device in creating 3-dimensional images in the examining area of dentistry and is one of the most common clinical methods in detecting second mesiobuccal (MB2) canals in maxillary molars. The aim of this in vitro study was to compare the image quality of the small field of view (FOV) CBCT with different rotation arcs and scanning speeds in the use of detecting root canals. METHODS: A dentate human skull was scanned in Morita 3D Accuitomo 170 with 4 × 4 cm FOV under 5 mA and 90 kVp. Two different rotation arcs (360° and 180°) and three different scanning modes (slow-speed mode, standard mode and high-speed mode) combined into six different groups. Five different levels of axial sections were selected from each group. Five endodontic specialists rated the image quality by focusing on the sharpness of the MB2 canal of the upper right first molar and the surrounding structures. RESULTS: Despite the rotation arcs, all the observers gave excellent ratings to images taken with slow-speed mode. The high-speed mode taken with 360° and 180° got the second lowest and the lowest ratings, respectively. Under the same scanning speed, the rotation arc did not have a significant difference in image quality. CONCLUSION: Slow-speed mode is inevitable in maintaining adequate image quality during taking CBCT. However, endodontists can use the half rotation mode to significantly reduce radiation dose, exposure time, and still maintain sufficient image quality for root canal anatomy assessment.

Assessment of the Release of Vascular Endothelial Growth Factor from 3D-Printed Poly-ε-Caprolactone/Hydroxyapatite/Calcium Sulfate Scaffold with Enhanced Osteogenic Capacity.

Vascular endothelial growth factor (VEGF) is one of the most crucial growth factors and an assistant for the adjustment of bone regeneration. In this study, a 3D scaffold is fabricated using the method of fused deposition modeling. Such a fabricated method allows us to fabricate scaffolds with consistent pore sizes, which could promote cellular ingrowth into scaffolds. Therefore, we drafted a plan to accelerate bone regeneration via VEGF released from the hydroxyapatite/calcium sulfate (HACS) scaffold. Herein, HACS will gradually degrade and provide a suitable environment for cell growth and differentiation. In addition, HACS scaffolds have higher mechanical properties and drug release compared with HA scaffolds. The drug release profile of the VEGF-loaded scaffolds showed that VEGF could be loaded and released in a stable manner. Furthermore, initial results showed that VEGF-loaded scaffolds could significantly enhance the proliferation of human mesenchymal stem cells (hMSCs) and human umbilical vein endothelial cells (HUVEC). In addition, angiogenic- and osteogenic-related proteins were substantially increased in the HACS/VEGF group. Moreover, in vivo results revealed that HACS/VEGF improved the regeneration of the rabbit's femur bone defect, and VEGF loading improved bone tissue regeneration and remineralization after implantation for 8 weeks. All these results strongly imply that the strategy of VEGF loading onto scaffolds could be a potential candidate for future bone tissue engineering.

Regeneration of Tooth with Allogenous, Autoclaved Treated Dentin Matrix with Dental Pulpal Stem Cells: An In Vivo Study.

INTRODUCTION: Biomaterials designed for tissue engineering should be nontoxic and nonimmunogenic and should achieve their intended functions. Treated dentin matrix (TDM), a bioactive extracellular matrix, is promising for tooth regeneration. However, the effect of sterilization on the surface properties of allogenous TDM in the animal model is unclear. METHODS: The biological characteristics and influences of dental pulp stem cells (DPSCs) with autoclaved TDM (a-TDM) were studied using scanning electron microscopy, immunofluorescence microscopy, immunohistochemistry, and reverse transcription polymerase chain reaction in vitro. In addition, a-TDM was implanted in a mouse model for 6 weeks and was a substrate with DPSCs for tooth reconstruction in a goat animal model in vivo. RESULTS: Allogenous a-TDM induced and supported DPSCs to develop new dentin pulp-like tissues, enamel dental pulp, and cementum periodontal complexes. Immunohistochemistry data showed that the markers dentin sialoprotein, ßⅢ-tubulin, dentin matrix protein 1, amelogenin, VIII factors, type I collagen, cementum-derived attachment protein, and scleraxis transcription factor were positive stained in toothlike tissue. CONCLUSIONS: Allogenous a-TDM served as an effective scaffold enabling DPSCs to proliferate and differentiate into a broad array of resident cells including odontoblasts, fibroblasts, vascular cells, and neural endings. Allogenous a-TDM with DPSCs can provide an ideal biomaterial for optimizing the regeneration of tooth material.

Development of calcium phosphate/calcium sulfate biphasic biomedical material with hyaluronic acid containing collagenase and simvastatin for vital pulp therapy.

OBJECTIVE: In vital pulp therapy (VPT), a barrier is created with appropriate capping to protect the remaining pulp and thus maintain pulp vitality. Here, we evaluated the feasibility of a biphasic calcium phosphate cement (CPC)-calcium sulfate hemihydrate (CSH) biomaterial containing simvastatin (Sim) and collagenase (Col) for VPT. METHODS: Combinations of varying CPC and CSH concentrations were analyzed for their handling properties and setting times, with their structures observed through scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDS). Drug release patterns of simvastatin and collagenase combined with CPC-CSH (CPC-CSH-Sim-Col) were also analyzed, followed by biocompatibility and bioactivity tests on human dental pulp stem cells (hDPSCs) and in vivo animal study in canine models; the in vivo results were obtained through microcomputed tomography and histological analysis. RESULTS: The results revealed that 70 wt% CPC (CPC7) with 30 wt% CSH (CSH3) exhibited optimal setting time and porous structure for clinical use. The cell viability and cytotoxicity analysis demonstrated that CPC7-CSH3 with or without simvastatin or collagenase did not injure hDPSCs. In vivo, the CPC7-CSH3-Sim-Col induced dentin bridge formation. SIGNIFICANCE: CPC7-CSH3-Sim-Col in this study has great potential as a VPT biomaterial to enhance the dentin bridge formation.

Crystal growth in dentinal tubules with bio-calcium carbonate-silica sourced from equisetum grass.

BACKGROUND/PURPOSE: One effective way to deal with dentin hypersensitivity is to develop materials to seal the tubules. The porous bio-calcium carbonate-silica (BCCS) contained well-dispersed CaCO3 would form calcium phosphates to seal the dentinal tubules when mixed with an acidic solution. The acidic hydrothermal treatment and calcination to isolate the BCCS from the agricultural waste like equisetum grass was used, which would be more environmentally friendly than chemically synthesized mesoporous biomaterials. The aim of this study was to develop mesoporous materials from natural resources to occlude the dentinal tubules which could be more environmentally-friendly. METHODS: Dentin disc samples were prepared and treated with different methods as follows: (1) BCCS mixed with H3PO4; (2) BCCS mixed with KH2PO4; (3) Seal & Protect® was used as a comparison group. Sealing efficacy was evaluated by measuring the depths and percentages of precipitate occlusion in dentinal tubules with SEM. RESULTS: The N2 adsorption-desorption isotherm of the BCCS demonstrated a pore size of around 15.0 nm and a surface area of 61 m2g-1. From the results of occlusion percentage and depth, the BCCS treated with H3PO4 or KH2PO4 demonstrated promising sealing efficacy than the commercial product. CONCLUSION: This synthetic process used the agricultural waste equisetum grass to produce bio-calcium carbonate-silica would be environmentally friendly, which has great potential in treating exposed dentin related diseases.