Enhanced Bone Formation by Rapidly Formed Bony Wall over the Bone Defect Using Dual Growth Factors

BACKGROUND@#In guided bone regeneration (GBR), there are various problems that occur in the bone defect after the wound healing period. This study aimed to investigate the enhancement of the osteogenic ability of the dual scaffold complex and identify the appropriate concentration of growth factors (GF) for new bone formation based on the novel GBR concept that is applying rapid bone forming GFs to the membrane outside of the bone defect. @*METHODS@#Four bone defects with a diameter of 8 mm were formed in the calvaria of New Zealand white rabbits each to perform GBR. Collagen membrane and biphasic calcium phosphate (BCP) were applied to the bone defects with the four different concetration of BMP-2 or FGF-2. After 2, 4, and 8 weeks of healing, histological, histomorphometric, and immunohistochemical analyses were conducted. @*RESULTS@#In the histological analysis, continuous forms of new bones were observed in the upper part of bone defect in the experimental groups, whereas no continuous forms were observed in the control group. In the histomorphometry, The group to which BMP-2 0.5 mg/ml and FGF-2 1.0 mg/ml was applied showed statistically significantly higher new bone formation. Also, the new bone formation according to the healing period was statistically significantly higher at 8 weeks than at 2, 4 weeks. @*CONCLUSION@#The novel GBR method in which BMP-2, newly proposed in this study, is applied to the membrane is effective for bone regeneration. In addition, the dual scaffold complex is quantitatively and qualitatively advantageous for bone regeneration and bone maintenance over time.

Setting time of root canal sealers and root-end filling materials by different measuring methods / 대한치과재료학회지

The aim of this study was to evaluate the differences in setting times based on the methods for dental root canal sealers and calcium silicate cement used in root-end filling. Five kinds of dental root canal sealers and four kinds of calcium silicate cement for root-end filling were selected for the experiments. All materials were mixed according to the manufacturers’ instructions and stored at 37 ℃ with a relative humidity of 95%. Setting time was measured using a 1/4 pound Gillmore needle and a 1 pound Gillmore needle to determine the time until indentation was no longer visible or the time until 2 mm penetration was no longer possible. The determination of indentation was based on the absence of visible impressions on the material surface when Gillmore needle was placed vertically. When comparing indentation time and penetration time using same type of Gillmore needle, only ProRoot MTA using 1 pound Gillmore needle showed significant difference between measuring methods (P0.05). By this study, we could expect to measure a setting time relatively similar to real clinical conditions through indentation method.

Preparation and characterization of uniform NiTi-O nanotubes on NiTi alloy / 대한치과재료학회지

This study aimed to optimize the cleaning process of the anodized specimens for fabricating clean NiTi-O nanotubes exhibiting visible light-mediated antibacterial activity at the surface of NiTi alloy. The cleaning process of the anodized specimens tested in this study was composed of two steps. The First step included two washing solvents (distilled water and heptane) with different washing times (1, 3, and 5 min) and temperatures (25 and 80 ℃), and the second step was treated by ultrasonicator (1, 3, and 5 min). From the results of FE-SEM observation, clean and uniform nanotubes (length: 600±80 nm, diameter: 52 ±5 nm) at the surface of NiTi alloy were observed on the condition of 5 min of washing in heptane at 25 ℃ and then 3 min of ultrasonication. Thin film XRD analysis resulted that the brookite TiO 2 crystal structure being detected in the anodized specimen. Furthermore, the live-dead assay resulted that there was no significant difference among the cell viability numbers of hMSCs cultured on a cell culture dish (control), NiTi alloy, and NiTi-O nanotubes (P>0.05). Therefore, the optimized cleaning process of the anodized NiTi alloy is expected to be more feasible for the NiTi alloy-based implant surface treatment technology.

Evaluation of the effect of vacuum heat treatment on the visible light remote-controlled drug release and antimicrobial activity of gold nanoparticle coated titania nanotubes / 대한치과재료학회지

The purpose of this study was to evaluate the effect of vacuum heat treatment on the visible light remote-controlled drug release and consequent antimicrobial activity of gold nanoparticles coated on the surface of titania nanotubes. After the plasma coating of gold nanoparticles on a titania nanotube with a diameter of 100 nm, a homogeneously spherical gold shaped nanoparticle deposited on titania nanotube specimen was prepared through a vacuum heat treatment process. From the measurement of the diffuse reflective ultraviolet-visible-near-infrared spectrophotometer, the vacuum heated gold nanoparticles-titania nanotubes showed strong light absorption at the range of 400 to 650 nm. From the observation of field emission scanning electron microscopy, the size of the nanoparticles increased from 5.59±1.05 nm to 56.93±10.91 nm, and the aspect ratio also increased from 1.01±0.31 to 1.55±0.47, as the gold coating time increased from 1 minute to 9 minutes, respectively. From the results of antimicrobial drug elution test and the antibacterial test using Streptococcus mutans, before and after the visible light (wavelength 550 nm) irradiation of the antimicrobial drug (a polylactic acid containing 0.1% tetracycline) coated specimen, the drug elution value of the experimental group subjected to visible light irradiation was significantly higher than that of the control group without light irradiation (P<0.05). Also, significant antibacterial effect was evident in the experimental group subjected to visible light irradiation (P<0.05). Therefore, the study concluded that there is a possibility as an antimicrobial implant material with a visible light remote control drug elution function with the surface treatment technology of gold nanoparticles-titania nanotubes spheroidized using vacuum heat treatment.

Evaluation of the effect of vacuum heat treatment on the visible light remote-controlled drug release and antimicrobial activity of gold nanoparticle coated titania nanotubes / 대한치과재료학회지

The purpose of this study was to evaluate the effect of vacuum heat treatment on the visible light remote-controlled drug release and consequent antimicrobial activity of gold nanoparticles coated on the surface of titania nanotubes. After the plasma coating of gold nanoparticles on a titania nanotube with a diameter of 100 nm, a homogeneously spherical gold shaped nanoparticle deposited on titania nanotube specimen was prepared through a vacuum heat treatment process. From the measurement of the diffuse reflective ultraviolet-visible-near-infrared spectrophotometer, the vacuum heated gold nanoparticles-titania nanotubes showed strong light absorption at the range of 400 to 650 nm. From the observation of field emission scanning electron microscopy, the size of the nanoparticles increased from 5.59±1.05 nm to 56.93±10.91 nm, and the aspect ratio also increased from 1.01±0.31 to 1.55±0.47, as the gold coating time increased from 1 minute to 9 minutes, respectively. From the results of antimicrobial drug elution test and the antibacterial test using Streptococcus mutans, before and after the visible light (wavelength 550 nm) irradiation of the antimicrobial drug (a polylactic acid containing 0.1% tetracycline) coated specimen, the drug elution value of the experimental group subjected to visible light irradiation was significantly higher than that of the control group without light irradiation (P<0.05). Also, significant antibacterial effect was evident in the experimental group subjected to visible light irradiation (P<0.05). Therefore, the study concluded that there is a possibility as an antimicrobial implant material with a visible light remote control drug elution function with the surface treatment technology of gold nanoparticles-titania nanotubes spheroidized using vacuum heat treatment.

Remineralization effect of experimental fluoride varnish with nano-sized hydroxyapatite and tricalcium phosphate / 대한치과재료학회지

The purpose of this study was to evaluate the remineralization effect of experimental fluoride varnish mixed with nano-tricalcium phosphate (TCP) and nano-hydroxyapatite (HA) on bovine teeth under demineralization and remineralization cycling by Vickers hardness. After fabrication of rosin-based experimental fluoride varnish with 5 wt% of NaF (EX) in the laboratory, 10 wt% of nano-hydroxyapatite (HA+EX) and nano-TCP (TC+EX) were mixed, respectively. Casein phosphopeptide-amorphous calcium phosphate (Tooth mousse) (CP) was used for comparison. Bovine incisors were impregnated by acrylic resin and exposed to caries inducing solution for 72 hours. EX, HA+EX, TC+EX, and CP were applied on the surface of bovine teeth. The specimens were immersed in a demineralization solution for 1 hour and in a re-mineralization solution for 23 hours and the cycle was repeated for 20 days. Vickers hardness was measured at baseline and after each treatment. CP group showed the highest hardness value at 24 hours after application of each material (p0.05).On the 10th day of de-/re-mineralization cycling, the TC+EX group showed the highest hardness value (p0.05). On the 20th day, the TC+EX group kept the highest hardness value, followed by HA+EX and EX groups (p<0.05). In conclusion, experimental fluoride varnish with 10 wt% of nano-TCP showed higher remineralization effect on the enamel of bovine teeth during the de/re-mineralization cycling.

Antibacterial sustainability of experimental fluoride varnish added with adhesive components / 대한치과재료학회지

The purpose of this study was to evaluate the sustainability of antibacterial effect against Streptococcus mutans of experimental fluoride varnish mixed with 2-hydroxyethyl methacrylate (HEMA) and/or glutaraldehyde. Experimental fluoride varnish (EX1) was fabricated. To make fluoride varnish with adhesive materials, EX1 was mixed with 5 wt% of glutaraldehyde (EX2), 35 wt% of HEMA (EX3) or both 5 wt% of glutaraldehyde and 35 wt% of HEMA (EX4). 5 μL of each experimental group was applied to 6 mm diameter polyethylene terephthalate film discs. Disks were stored in distilled water in a shaking incubator at 37℃ for 1 hour, 3 hours, 8 hours, 12 hours, 24 hours, 5 days and 10 days. The antibacterial activities against S. mutans were evaluated by agar diffusion test with the discs at each time. The antibacterial activities were sustained up to 10 days in all groups. The antibacterial activities of EX3 and EX4 were significantly higher than other groups from 8 hours to 10 days and there were no significant differences from EX2 at 10 days. HEMA with and without glutaraldehyde can be applied to fluoride varnish to increase the sustainability of antibacterial activities.

Efficacy of the extract of Brachypodium sylvaticum as a preventive and an improving agent of periodontal disease / 대한치과재료학회지

We evaluated the antibacterial, anti-inflammatory, and inhibitory effect of osteoclast differentiation of Brachypodium sylvaticum (BS) to find out the possibility of preventing periodontal disease. The inhibition of Porphyromonas gingivalis (P. gingivalis) growth by BS and the sustainability of the antibacterial activity was assessed. The production of pro-inflammatory cytokines from lipopolysaccharide (LPS)-induced RAW 264.7 cells were measured using enzyme-linked immunosorbent assays (ELISA), and the production of nitric oxide (NO) and cell viability were measured. Osteoclast differentiation was evaluated by Tartrate-resistant acid phosphatase (TRAP) staining, and TRAP activity. BS showed significant antibacterial activity and sustainable antibacterial activity in P. gingivalis. We also found out that the BS significantly decreased secretion of pro-inflammatory cytokines [tumor necrosis factor (TNF-α) and interleukin-6 (IL-6)] and NO production without cytotoxicity. Furthermore, BS inhibited the differentiation of bone marrow macrophages (BMMs) obtained from mouse bone marrow cells into osteoclasts without cytotoxicity. Taken together, BS can be a promising candidate for a preventive and improving agent of periodontal disease having antibacterial, anti-inflammatory, and inhibitory effects of osteoclast differentiation.

Sustained antibacterial effects of antibacterial agents against Streptococcus mutans applied on hydroxyapatite disc / 대한치과재료학회지

This study aimed to evaluate the antibacterial activities sustainability of antibacterial agents mixed with experimental fluoride varnish on hydroxyapatite disc against Streptococcus mutans (S. mutans). On the hydroxyapatite disc with 4.8 mm of diameter, 5 μL of 1 mM antibacterial agents mixed with experimental fluoride varnish were applied. Positive control and vehicle control were 10 μg/mL ampicillin and dimethyl sulfoxide (DMSO) mixed with fluoride varnish, respectively. The discs were stored in distilled water in a 37℃ shaking water bath at 120 rpm for 30 minutes, 4 hours, 1 day, 5 days, 20 days, and 30 days. Antibacterial activities were evaluated with the inhibition zone by the agar diffusion test. The antibacterial activities of all antibacterial agents were sustained for 30 days. Among them, Bakuchiol, Bavachromene, and Bavachalcone showed higher antibacterial activities for up to 30 days. The antibacterial agents when mixed in the experimental fluoride varnish with increased and prolonged antibacterial activities can be applied to prevent dental caries effectively.

Remineralization effect of experimental fluoride varnish with nano-sized hydroxyapatite and tricalcium phosphate / 대한치과재료학회지

The purpose of this study was to evaluate the remineralization effect of experimental fluoride varnish mixed with nano-tricalcium phosphate (TCP) and nano-hydroxyapatite (HA) on bovine teeth under demineralization and remineralization cycling by Vickers hardness. After fabrication of rosin-based experimental fluoride varnish with 5 wt% of NaF (EX) in the laboratory, 10 wt% of nano-hydroxyapatite (HA+EX) and nano-TCP (TC+EX) were mixed, respectively. Casein phosphopeptide-amorphous calcium phosphate (Tooth mousse) (CP) was used for comparison. Bovine incisors were impregnated by acrylic resin and exposed to caries inducing solution for 72 hours. EX, HA+EX, TC+EX, and CP were applied on the surface of bovine teeth. The specimens were immersed in a demineralization solution for 1 hour and in a re-mineralization solution for 23 hours and the cycle was repeated for 20 days. Vickers hardness was measured at baseline and after each treatment. CP group showed the highest hardness value at 24 hours after application of each material (p0.05).On the 10th day of de-/re-mineralization cycling, the TC+EX group showed the highest hardness value (p0.05). On the 20th day, the TC+EX group kept the highest hardness value, followed by HA+EX and EX groups (p<0.05). In conclusion, experimental fluoride varnish with 10 wt% of nano-TCP showed higher remineralization effect on the enamel of bovine teeth during the de/re-mineralization cycling.

Antibacterial sustainability of experimental fluoride varnish added with adhesive components / 대한치과재료학회지

The purpose of this study was to evaluate the sustainability of antibacterial effect against Streptococcus mutans of experimental fluoride varnish mixed with 2-hydroxyethyl methacrylate (HEMA) and/or glutaraldehyde. Experimental fluoride varnish (EX1) was fabricated. To make fluoride varnish with adhesive materials, EX1 was mixed with 5 wt% of glutaraldehyde (EX2), 35 wt% of HEMA (EX3) or both 5 wt% of glutaraldehyde and 35 wt% of HEMA (EX4). 5 μL of each experimental group was applied to 6 mm diameter polyethylene terephthalate film discs. Disks were stored in distilled water in a shaking incubator at 37℃ for 1 hour, 3 hours, 8 hours, 12 hours, 24 hours, 5 days and 10 days. The antibacterial activities against S. mutans were evaluated by agar diffusion test with the discs at each time. The antibacterial activities were sustained up to 10 days in all groups. The antibacterial activities of EX3 and EX4 were significantly higher than other groups from 8 hours to 10 days and there were no significant differences from EX2 at 10 days. HEMA with and without glutaraldehyde can be applied to fluoride varnish to increase the sustainability of antibacterial activities.

Efficacy of the extract of Brachypodium sylvaticum as a preventive and an improving agent of periodontal disease / 대한치과재료학회지

We evaluated the antibacterial, anti-inflammatory, and inhibitory effect of osteoclast differentiation of Brachypodium sylvaticum (BS) to find out the possibility of preventing periodontal disease. The inhibition of Porphyromonas gingivalis (P. gingivalis) growth by BS and the sustainability of the antibacterial activity was assessed. The production of pro-inflammatory cytokines from lipopolysaccharide (LPS)-induced RAW 264.7 cells were measured using enzyme-linked immunosorbent assays (ELISA), and the production of nitric oxide (NO) and cell viability were measured. Osteoclast differentiation was evaluated by Tartrate-resistant acid phosphatase (TRAP) staining, and TRAP activity. BS showed significant antibacterial activity and sustainable antibacterial activity in P. gingivalis. We also found out that the BS significantly decreased secretion of pro-inflammatory cytokines [tumor necrosis factor (TNF-α) and interleukin-6 (IL-6)] and NO production without cytotoxicity. Furthermore, BS inhibited the differentiation of bone marrow macrophages (BMMs) obtained from mouse bone marrow cells into osteoclasts without cytotoxicity. Taken together, BS can be a promising candidate for a preventive and improving agent of periodontal disease having antibacterial, anti-inflammatory, and inhibitory effects of osteoclast differentiation.

Sustained antibacterial effects of antibacterial agents against Streptococcus mutans applied on hydroxyapatite disc / 대한치과재료학회지

This study aimed to evaluate the antibacterial activities sustainability of antibacterial agents mixed with experimental fluoride varnish on hydroxyapatite disc against Streptococcus mutans (S. mutans). On the hydroxyapatite disc with 4.8 mm of diameter, 5 μL of 1 mM antibacterial agents mixed with experimental fluoride varnish were applied. Positive control and vehicle control were 10 μg/mL ampicillin and dimethyl sulfoxide (DMSO) mixed with fluoride varnish, respectively. The discs were stored in distilled water in a 37℃ shaking water bath at 120 rpm for 30 minutes, 4 hours, 1 day, 5 days, 20 days, and 30 days. Antibacterial activities were evaluated with the inhibition zone by the agar diffusion test. The antibacterial activities of all antibacterial agents were sustained for 30 days. Among them, Bakuchiol, Bavachromene, and Bavachalcone showed higher antibacterial activities for up to 30 days. The antibacterial agents when mixed in the experimental fluoride varnish with increased and prolonged antibacterial activities can be applied to prevent dental caries effectively.

Diffuse reflection characterization and visible light mediated antibacterial effect of Pt-TiO2 nanotubes / 대한치과재료학회지

The purpose of this study was to fabricate platinum (Pt), one of the plasmonic nanoparticles that induces localized surface plasmon resonance (LSPR) effects caused by the pairing of plasmon with the electric field of visible-near infrared light, coated 100 nm titania (Pt-TiO2) nanotubes to evaluate the surface properties and laser mediated antibacterial effects. From the analysis of UV-VIS-NIR spectrum, the light absorptions of Pt-TiO2 nanotubes were detected at wavelengths 399–429 nm, 527–579 nm, and 806–906 nm, respectively, and one of the detected wavelengths was suitable for the laser used in this study (OCLA, Wavelength: 405). From the observation of FE-SEM, as the platinum coating time increased, the inner diameter of the Pt-TiO2 nanotubes decreased from 68.8 nm to 48.8 nm, and the shape of the platinum nanoparticles coated on the top layer of the titania nanotubes changed from spherical to rod. From the results of contact angle measurement, the contact angle of water increased from 11.94°to 19.84°as the platinum coating time increased from 1 minute to 3 minutes. The Staphylococcus aureus antibacterial test resulted that 98% or more bacterial reduction of all Pt-TiO2 nanotube groups were observed after laser irradiation (P<0.05). Live-dead assay and MTT assay indicated that laser irradiation did not affect cell death. Therefore, Pt–TiO2 nanotube exhibiting a local surface plasmon resonance effect is expected to have many potentials for semi-permanent antimicrobial implant surface treatment without antibacterial drugs.

Improvement of the osteogenic potential of ErhBMP-2-/EGCG-coated biphasic calcium phosphate bone substitute: in vitro and in vivo activity

PURPOSE: The aim of this study was to evaluate the enhancement of osteogenic potential of biphasic calcium phosphate (BCP) bone substitute coated with Escherichia coli-derived recombinant human bone morphogenetic protein-2 (ErhBMP-2) and epigallocatechin-3-gallate (EGCG). METHODS: The cell viability, differentiation, and mineralization of osteoblasts was tested with ErhBMP-2-/EGCG solution. Coated BCP surfaces were also investigated. Standardized, 6-mm diameter defects were created bilaterally on the maxillary sinus of 10 male New Zealand white rabbits. After removal of the bony windows and elevation of sinus membranes, ErhBMP-2-/EGCG-coated BCP was applied on one defect in the test group. BCP was applied on the other defect to form the control group. The animals were sacrificed at 4 or 8 weeks after surgery. Histologic and histometric analyses of the augmented graft and surrounding tissue were performed. RESULTS: The 4-week and 8-week test groups showed more new bone (%) than the corresponding control groups (P<0.05). The 8-week test group showed more new bone (%) than the 4-week test group (P<0.05). CONCLUSIONS: ErhBMP-2-/EGCG-coated BCP was effective as a bone graft material, showing enhanced osteogenic potential and minimal side effects in a rabbit sinus augmentation model.

Effect of accelerated aging on long-term accuracy of full arches manufactured using various 3-dimensional printers / 대한치과재료학회지

Full arch models play an important role in clear aligner orthodontic therapy and the preparation of prosthodontic appliances. Three dimensional (3D) printed full arches are very popular with the benefit of easy production and good mechanical properties for fabricating clear aligner. However, the accuracy of 3D printed full arches after long storage have not been proved yet. The objective of this study was to estimate the long-term accuracy of 3D full arches produced by the four types of 3D printers (stereo-lithography apparatus (SLA), digital light projector (DLP), Polyjet™ (POL), and fused deposition modeling (FDM)) following an accelerated aging treatment. The highest accuracy was produced by POL (before treatment) and SLA (after treatment) group, respectively. Comparisons between absolute mean trueness for the 3D printed full arches before and after treatment indicated that the deviation of the trueness values of FDM group were significantly higher than those of other experimental groups (p<0.05). In addition, all trueness relative errors for FDM group were greater than 0.04 after treatment, which was high compared to those of other experimental groups. Therefore, the long-term storage of full arches fabricated by FDM type 3D printer is not recommended and the 3D printed full arches should be used immediately whenever possible.

Minimum inhibitory concentration and minimum bactericidal concentration of antibacterial fluoride varnish / 대한치과재료학회지

The aim of this study was to investigate the antibacterial effect of fluoride varnish with antibacterial agents on Streptococcus mutans (S. mutans). Experimental fluoride varnish (EFV) with 5% NaF was fabricated. Five antibacterial agents were tested with 1 mM and 10 mM concentrations, respectively: Bakuchiol (BAK), Bavachalcone (BCC), Isobavachromene (IBC), and Bavachromene (BCM). MIC and MBC test was performed by antibacterial agents with and without EFV using 1.1 × 10¹⁰ CFU/ml of S. mutans. Cell viability test were performed using MTT test. Statistical analysis was done with ANOVA and Duncan's multiple range test at α=0.05. In the antibacterial agents without EFV, the MIC of BAK, BCC, and IBC was the lowest (0.015 mM), and the MBC of BAK was the lowest (0.031 mM). For the antibacterial agents with EFV, the MIC (0.031 mM) and MBC (0.062 mM) of BAK was the lowest, respectively. In MTT test, 1 mM BCM showed the highest cell viability (P < 0.05). This study suggest that BAK can be applied the fluoride varnish under the control of the concentration to develop antibacterial fluoride varnish.

Titania nanotube template based synthesis of gold nanotubes and their antibacterial activity / 대한치과재료학회지

In this study, gold nanotubes were fabricated by electrophoretic deposition using a titania nanotube layer as a template, and then the surface characteristics, biocompatibility and antibacterial effect of gold nanotubes were evaluated. Gold nanotubes of 100 nm diameter were fabricated by depositing 4 nm and 15 nm gold nanoparticles on anodized 100 nm titania nanotubes by citrate reduction and electrophoretic deposition. As a result of the UV-Vis diffuse spectrophotometer, 4 nm and 15 nm gold nanotubes showed strong absorption at 702~774 nm and 753~760 nm, respectively. Also, the maximum absorption wavelength was shifted to the longer wavelength as the coating time of the gold nanoparticles increased. FE-SEM observation and EDX analysis resulted that 0.1~0.5 wt% gold nanoparticles uniformly were stacked on the top layer of titania nanotubes. As a result of MTT cell test, the relative absorbance value of all experimental groups after 24 hours and 48 hours of incubation exceeded 70% indicating excellent biocompatibility. The effect of the near infrared laser light on the adhesion and growth of gold nanotubes showed excellent antibacterial activity regardless of the coating time of gold nanoparticles. Therefore, it is confirmed that the gold nanotube coating technology based on the titania nanotube template is supposed to be highly applicable to a titanium implant surface treatment technology with the remote control thermal treatment of a near-infrared laser.

The evaluation of the shear bond strength between various Hybrid CAD/CAM restorative materials and repairing composite resins / 대한치과재료학회지

The purpose of this study was to evaluate the shear bond strengths between various hybrid computer-aided design (CAD)/computer-aided manufacturing (CAM) restorative materials and repairing resin. Two resin network-based hybrid (Lava Ultimate and Polyglass), one ceramic framework-based hybrid (Enamic), and one zirconia (Zenotec Zr bridge) CAD/CAM restorative materials were used in this study. The shear bond strength test and failure modes of four experimental groups designated LUS (Lava Ultimate), ENA (Enamic), PGB (Polyglass), and ZBR (zirconia control group) were characterized in this study. The hybrid CAD/CAM restorative materials showed stronger shear bond strengths in the sequence of PGB, LUS, and ENA (P < 0.05). The shear bond strengths of PGB and LUS groups showed significantly higher than those of ZBR (P < 0.05), while ENA did not show any significant difference from ZBR (P < 0.05). The PEG and LUS groups mostly exhibited cohesive failure, but the ENA and ZBR groups predominantly showed adhesive failure. Therefore, resin network-based hybrid CAD/CAM restorative materials such as Lava Ultimate and Polyglass should be more useful for intra-oral repairs.

Four-week histologic evaluation of grafted calvarial defects with adjunctive hyperbaric oxygen therapy in rats

PURPOSE: The aim of this study was to characterize the healing in the grafted calvarial defects of rats after adjunctive hyperbaric oxygen therapy. METHODS: Twenty-eight male Sprague-Dawley rats (body weight, 250–300 g) were randomly divided into two treatment groups: with hyperbaric oxygen therapy (HBO; n=14) and without HBO (NHBO; n=14). Each group was further subdivided according to the bone substitute applied: biphasic calcium phosphate (BCP; n=7) and surface-modified BCP (mBCP; n=7). The mBCP comprised BCP coated with Escherichia-coli-derived recombinant human bone morphogenetic protein-2 (ErhBMP-2) and epigallocatechin-3-gallate (EGCG). Two symmetrical circular defects (6-mm diameter) were created in the right and left parietal bones of each animal. One defect was assigned as a control defect and received no bone substitute, while the other defect was filled with either BCP or mBCP. The animals were allowed to heal for 4 weeks, during which those in the HBO group underwent 5 sessions of HBO. At 4 weeks, the animals were sacrificed, and the defects were harvested for histologic and histomorphometric analysis. RESULTS: Well-maintained space was found in the grafted groups. Woven bone connected to and away from the defect margin was formed. More angiogenesis was found with HBO and EGCG/BMP-2 (P<0.05). None of the defects achieved complete defect closure. Increased new bone formation with HBO or EGCG/BMP-2 was evident in histologic evaluation, but it did not reach statistical significance in histometric analysis. A synergic effect between HBO and EGCG/BMP-2 was not found. CONCLUSIONS: Within the limitations of this study, the present findings indicate that adjunctive HBO and EGCG/BMP-2 could be beneficial for new bone formation in rat calvarial defects.