Contribution of Capsule Endoscopy Early in a Bleeding Episode to Treatment of Small Bowel Angioectasia: A Case Report.

Background: Recent advances in endoscopic devices such as small bowel capsule endoscopy and balloon-assisted endoscopy have improved the level of medical care for small bowel bleeding. However, treating small bowel angioectasia remains challenging because repeated intermittent bleeding can occur from the multiple minute lesions (about 1 mm in size) that develop in a synchronous and metachronous manner. Here, we report a case of small bowel angioectasia in which capsule endoscopy performed early in a bleeding episode contributed to treatment. Case Summary: A 66-year-old man with suspected small bowel bleeding underwent small bowel capsule endoscopy and balloon-assisted endoscopy with argon plasma coagulation hemostasis for a small intestinal angioectasia. Because small bowel bleeding recurred intermittently after the treatment, small bowel capsule endoscopy and balloon-assisted endoscopy were repeated when there was no bleeding, but no abnormalities were found. Subsequent small bowel capsule endoscopy during a bleeding episode revealed bloody intestinal fluid in the proximal small intestine. Peroral balloon-assisted endoscopy was performed 2 days after SBCE for detailed observation of the small intestinal mucosa at the suspected bleeding site, and there a 1-mm Dieulafoy's lesion with no active bleeding was identified. We performed argon plasma coagulation, and no bleeding was observed thereafter. Conclusions: Small bowel capsule endoscopy immediately after bleeding onset can identify the bleeding source of multiple minute lesions in small bowel angioectasia.

[A Case of a Massive Retropharyngeal Hematoma Associated with Traumatic Cervical Cord Injury].

Retropharyngeal hematomas are uncommon, but they may rarely cause occlusion of the upper airway and threaten life. Retropharyngeal hematomas often occur due to head or neck injury;they rarely occur due to iatrogenic causes such as insertion of a gastric tube or anticoagulant therapy. It has been found that patients receiving anticoagulant therapy are more likely to experience potentially severe retropharyngeal hematomas. We report the case of a patient with retropharyngeal hematoma with cervical cord damage. A 75-year-old man was transferred to our hospital after he sustained a fall and damaged his face. CT showed a massive retropharyngeal hematoma, but he did not complain of any breathing issues. Therefore, we selected conservative therapy. However, after approximately 4 hours, he suddenly complained of breathing problems and suffered from loss of consciousness. We performed intubation and provided sedation. After one week, his condition clearly improved and he was extubated.

Essential roles of G9a in cell proliferation and differentiation during tooth development.

Teeth develop through interactions between epithelial and mesenchymal tissues mediated by a signaling network comprised of growth factors and transcription factors. However, little is known about how epigenetic modifiers affect signaling pathways and thereby regulate tooth formation. We previously reported that the histone 3 lysine 9 (H3K9) methyltransferase (MTase) G9a is specifically enriched in the tooth mesenchyme during mouse development. In this study, we investigated the functions of G9a in tooth development using G9a conditional knockout (KO) mice. We used Sox9-Cre mice to delete G9a in the tooth mesenchyme because Sox9 is highly expressed in the mesenchyme derived from the cranial neural crest. Immunohistochemical analyses revealed that G9a expression was significantly decreased in the mesenchyme of Sox9-Cre;G9afl/fl (G9a cKO) mice compared with that in Sox9-Cre;G9a fl/+(control) mice. Protein levels of the G9a substrate H3K9me2 were also decreased in the tooth mesenchyme. G9a cKO mice showed smaller tooth germ after embryonic day (E) 16.5 and E17.5, but not at E15.5. The developing cusp tips, which were visible in control mice, were absent in G9a cKO mice at E17.5. At 3 weeks after birth, small first molars with smaller cusps and unseparated roots were formed. Organ culture of tooth germs derived from E15.5 cKO mouse embryos showed impaired tooth development, suggesting that tooth development per se is affected independently of skull development. BrdU labeling experiments revealed that the proliferation rates were decreased in the mesenchyme in G9a cKO mice at E17.5. In addition, the proliferation rates in the tooth inner enamel epithelium were also decreased. In situ hybridization revealed altered localization of genes associated with tooth development. In cKO mice, intensively localized expression of mRNAs encoding bone morphogenic protein (Bmp2 and Bmp4) was observed in the tooth mesenchyme at E17.5, similar to the expression patterns observed in control mice at E15.5. Localization of Shh and related signaling components, including Gli1, Ptch1, and Ptch2, in the tooth mesenchyme of cKO mice was generally similar to that at earlier stages in control mice. In addition, expression of Fgf3 and Fgf10 in the mesenchyme was decreased in G9a cKO mice at P0. Expression levels of Fgf9 and p21, both of which were expressed in the secondary enamel-knot, were also decreased. Thus, the expression of genes associated with tooth development was delayed in cKO mice. Our results suggest that H3K9MTase G9a regulates cell proliferation and timing of differentiation and that G9a expression in the tooth mesenchyme is required for proper tooth development.

Prostaglandin E-Major Urinary Metabolite as a Biomarker for Inflammation in Ulcerative Colitis: Prostaglandins Revisited.

With the development of new therapeutic approaches, the ultimate goal of ulcerative colitis (UC) treatment is not only clinical remission but also mucosal healing. Successful mucosal healing has been associated with a dramatic risk reduction in UC recurrence and colitis-associated cancer development, which are the most critical complications of UC. However, invasive tests such as colonoscopy and biopsy are required to evaluate mucosal healing. Therefore, frequent examinations are unsuitable for UC patients. Mucosal inflammation of the colon and prostaglandin E2 production are assumed to be correlated; therefore, we considered that prostaglandin E-major urinary metabolite (PGE-MUM; 7-hydroxy-5,11-diketotetranor-prosta-1,16-dioic acid) may be a surrogate biomarker of UC activity. In this review, we propose that PGE-MUM levels reflect the colonoscopic and histological appearance of UC, suggesting that it is a more sensitive biomarker than those previously utilized for UC-related mucosal inflammation. According to the 'organ-specific chronic inflammation-carcinoma sequence' theory, by measuring PGE-MUM periodically, it would be possible to control inflammation, with subsequent prevention of UC recurrence and colitis-associated cancer development. The measurement of urine samples for PGE-MUM - a simple, noninvasive method - can reduce the patient burden as well as medical costs, suggesting its potential for application in routine practice.

Melatonin enhances vertical bone augmentation in rat calvaria secluded spaces.

BACKGROUND: Melatonin has many roles, including bone remodeling and osseointegration of dental implants. The topical application of melatonin facilitated bone regeneration in bone defects. We evaluated the effects of topical application of melatonin on vertical bone augmentation in rat calvaria secluded spaces. MATERIAL AND METHODS: In total, 12 male Fischer rats were used and two plastic caps were fixed in the calvarium. One plastic cap was filled with melatonin powder and the other was left empty. RESULTS: Newly generated bone at bone defects and within the plastic caps was evaluated using micro-CT and histological sections. New bone regeneration within the plastic cap was increased significantly in the melatonin versus the control group. CONCLUSIONS: Melatonin promoted vertical bone regeneration in rat calvaria in the secluded space within the plastic cap.

Effects of intermittent administration of parathyroid hormone on bone augmentation in rat calvarium.

OBJECTIVES: This study examined the effects of parathyroid hormone (PTH) on bone augmentation beyond the skeletal envelope within a plastic cap in rat calvaria. MATERIALS AND METHODS: The calvaria of 30 rats were exposed, and 2 plastic caps were placed on each. Each of the 10 rats was treated with 35 or 105 µg/kg (PTH-35, PTH-105) PTH 3 times per week. The control group was injected with sterile saline 3 times per week. Micro-computed tomography (CT) imaging was performed every 2 weeks for 12 weeks. Micro-CT and histological sections were used to determine the amount of bone augmentation within the plastic caps. Bone volume (BV) was calculated using BV-measuring software. RESULTS: The histomorphometric and histological analyses showed that the amount of bone augmentation was increased significantly in the PTH groups compared with the controls at 12 weeks. The PTH-105 group showed significantly more bone augmentation and osteoblasts compared with the PTH-35 group. CONCLUSIONS: These results indicate that the higher the dose of intermittent PTH administered, the greater the amount of bone formation beyond the skeletal envelop in the rat calvarium.

Histological, mechanical, and radiological study of osteoformation in titanium foam implants.

BACKGROUND: Titanium (Ti) is widely used for implants because of its high mechanical reliability and because it aids osteoformation. However, it also produces artifacts during radiological imaging. Further, Ti implants can sometimes cause the surrounding bone to break. Owing to recent advances, Ti can be transformed into sponge-like, porous materials having a three-dimensional network of pores; such materials are called Ti foams. These foams exhibit distinct characteristics that make them more suitable than nonporous Ti. The objective of this study was to evaluate Ti foams as implant materials. METHODS: Implants based on Ti foams having porosities of 80% and 90% were embedded in the femurs of 11 rabbits. Implants based on 0% porosity Ti were used as controls. Five rabbits were sacrificed 4 weeks after implantation, while the remaining were sacrificed after 12 weeks. The femurs containing the Ti implants were harvested and analyzed. RESULTS: Biomechanical analyses showed that the 80% porosity implants induced greater osteoformation. There were significant differences in the average pushout strengths of the control and 80% porosity implants after 4 weeks (p = 0.048) and 12 weeks (p = 0.001). Histopathological analyses confirmed osteoformation in the case of the 80% porosity implants. Analyses of the micro-computed tomography images of the Ti foam-based implants did not suggest the presence of artifacts. CONCLUSIONS: The 80% porosity Ti implants did not exhibit the shortcomings associated with conventional Ti implants. In addition, they induced greater osteoformation. Finally, the Ti foams did not produce radiological artifacts.

Reduction of cervical vertebra ghost images in panoramic radiography using vertical dual exposure.

PURPOSE: To evaluate the image quality of vertical dual-exposure panoramic radiography (PR), which merges two PR images taken at different focus heights to reduce ghost images of cervical vertebrae (CV) and intervertebral spaces (IVS) in the incisor region. METHODS: PR images of an aluminum block, a CV phantom and a human head phantom were taken at 0 mm and merged with and subtracted from PR images taken at other heights (0, 5, 10, 15, and 20 mm) to create new images, e.g., Merg0 + 15 mm and Sub0 - 10 mm. The subtracted images were analyzed subjectively according to the uniformity on the line profile. Merged images were evaluated subjectively by six raters to determine the influence of the ghost images. RESULTS: Objective evaluation revealed a positional shift in the ghost images according to the height of the focus for both phantoms. In the subjective evaluation, the normal PR (Merg0 + 0 mm) showed the worst score, indicating strong influence of CV and IVS ghost images. CONCLUSION: The vertical dual-exposure PR method, which merges PR images taken at the normal position and a higher X-ray focus, can reduce CV and IVS ghost images in the incisor region.

Vertical magnification correction in vertical dual-exposure panoramic radiography.

PURPOSE: To clarify the magnification error caused by the degree of tilt of the incisor and the elevation of the X-ray focus position, and the verification effect of magnification correction when performing vertical dual-exposure panoramic radiography. METHODS: Panoramic radiographic images of a phantom embedding 26 steel balls were taken at different heights (0, 5, 10, 15, and 20 mm) and tilt angles (0°, 10°, 20°, and 30°) to evaluate vertical magnification in each condition. Error and correlation coefficients in the vertical magnifications were calculated between the measured and theoretical magnification values. RESULTS: The more the steel ball phantom was tilted, the more the images of the uppermost steel balls were laterally stretched. In the vertical direction, image magnification also influenced the tilt angle of the object in the incisal region. The range of error in vertical magnification was -0.35-0.30%. The Spearman's rank correlation coefficient between the measured and theoretical magnification value was 0.983. CONCLUSION: Vertical magnification correction has the potential to improve image quality when merging panoramic radiographs in vertical dual-exposure panoramic radiography.

Resorbable bilayer membrane made of L-lactide-ε-caprolactone in guided bone regeneration: an in vivo experimental study.

PURPOSE: Guided bone regeneration (GBR) is an accepted method in dental practice that can successfully increase the bone volume of the host at sites chosen for implant placement; however, existing GBR membranes exhibit rapid absorption and lack of adequate space maintenance capabilities. We aimed to compare the effectiveness of a newly developed resorbable bilayer membrane composed of poly (L-lactic acid) and poly (-caprolactone) (PLACL) with that of a collagen membrane in a rat GBR model. METHODS: The rat calvaria was used as an experimental model, in which a plastic cylinder was placed. We operated on 40 male Fisher rats and subsequently performed micro-computed tomography and histomorphometric analyses to assess bone regeneration. RESULTS: Significant bone regeneration was observed, which was and similar across all the experimental groups. However, after 24 weeks, the PLACL membrane demonstrated significant resilience, and sporadic partial degradation. This extended preservation of the barrier effect has great potential to facilitate optimal bone regeneration. CONCLUSIONS: The PLACL membrane is a promising alternative to GBR. By providing a durable barrier and supporting bone regeneration over an extended period, this resorbable bilayer membrane could address the limitations of the current membranes. Nevertheless, further studies and clinical trials are warranted to validate the efficacy and safety of The PLACL membrane in humans.

Effects of nicotine on guided bone augmentation in rat calvarium.

OBJECTIVE: A limited number of experimental animal studies and in vitro studies have confirmed that nicotine impairs bone healing, diminishes osteoblast function, causes autogenous bone graft morbidity, and decreases graft biomechanical properties. The aim of this study was the histomrphometric assessment of the effect of nicotine on guided bone augmentation in a rat model. MATERIAL AND METHODS: Twenty-four male Wistar rats were randomly divided into a nicotine group and a control group. All animals received either nicotine (3 mg/kg) or saline 4 weeks before the surgical procedure and continued to receive nicotine or saline from surgery until death at 12 weeks. Two plastic caps were placed in the exposed calvaria of rats. Images of bone augmentation within the plastic caps were then taken using microfocus computed tomography (micro-CT). Histological sections were cut along the same plane as that used for micro-CT images. RESULTS: Bone augmentation beyond the skeletal envelope occurred in both the nicotine and control groups. However, the nicotine group showed significantly smaller increases in bone volume and bone height than the controls. CONCLUSION: Nicotine jeopardized, but did not prevent, the process of guided bone augmentation in a rat model.

Micro-CT observation of angiogenesis in bone regeneration.

OBJECTIVES: Restoration of an adequate blood supply is essential for the bone healing process and is key to the success of bone augmentation procedures. In this study, we evaluated angiogenesis in rat calvarial flat bone defects using in vivo microfocus computed tomography (micro-CT). MATERIALS AND METHODS: Twenty rats were used. The calvarium was exposed and calvarial bone defects of critical (5-mm diameter) and non-critical (2.7-mm diameter) sizes were prepared. Bone regeneration and angiogenesis were evaluated by image analysis using micro-CT and histological examination. RESULTS: Critical- and non-critical-sized calvarial bone defects showed bone regeneration and angiogenesis around the midsagittal suture. Critical-sized calvarial bone defects showed approximately 1.2% reossification of the original surgical defect, whereas the non-critical-sized defects showed approximately 43.3% reossification at day 28. Furthermore, angiogenesis was observed later in the critical-sized calvarial bone defects (about 38.2%), whereas angiogenesis was observed early in the non-critical-sized calvarial bone defects (about 75.5%) at day 28. New blood vessel networks were observed around defects of both sizes. CONCLUSIONS: Angiogenesis preceded bone regeneration around critical- and non-critical-sized calvarial bone defects. Angiogenesis led to full bone formation in non-critical-sized defects.

FGF-2 angiogenesis in bone regeneration within critical-sized bone defects in rat calvaria.

OBJECTIVE: This study examined the effect of basic fibroblast growth factor (FGF)-2 with an absorbable collagen sponge on angiogenesis and bone regeneration in rat calvarial critical-sized bone defects using microcomputed tomography. METHODS: Forty 7-week-old male Fischer rats were used. The symmetrical critical-sized calvarial bone defects (5 mm diameter) were created. An absorbable collagen sponge with or without FGF-2 (0.1% or 0.3%) was implanted into each bone defect. RESULTS: Blood vessel and bone volumes were significantly higher in the 0.3% FGF-2 group compared with the control and 0.1% FGF-2 groups on day 28. Significantly more osteoblast- and osteoclast-like cells were seen in the 0.3% FGF-2 group. CONCLUSIONS: Thus, FGF-2 increased blood vessel and bone formation in rat calvarial critical-sized bone defects.

A longitudinal study of the effect of experimental osteoporosis on bone trabecular structure in the rat mandibular condyle.

The authors performed a longitudinal study of the microstructural changes occurring in the mandibular condyle during osteoporosis using the findings obtained from micro-CT. The subjects used in this study were eight Sprague-Dawley rats. Among them, five were administered the immunosuppressant drug FK506 by injection for five weeks, while the other three were administered saline solution in the same manner. Micro-CT images were taken of the bilateral mandibular condyle, hip, and knee joints in all animals on days 1, 8, 15, 22, 29, and 36 following injection. Six indices of morphometric analysis were compared between the two groups. Significant differences were observed in BV/TV, Tb.Th, Tb.N, and Tb.Sp in the mandibular condyle, while trabecular bone density appeared to decrease in the immunosuppressant group on three-dimensional (3D) imaging. And, in comparison with the mandibular condyle and femur, they were similar. These results suggested that osteoporosis affects not only the femur, but also the mandibular condyle.

Correction of intraoral radiography with dual imaging plates using enlargement of the horizontal direction with division into 12 blocks.

PURPOSE: The dual imaging plate (DIP) method, which synthesizes intraoral radiographs from a front imaging plate (FIP) and a back imaging plate (BIP), produces adequate image quality and allows the radiation dose to be reduced. However, there are slight errors in superimposition and alignment between the FIP and BIP. The aim of this study was to establish positional correction in the DIP method and evaluate the effect. METHODS: Six sets of two imaging plates were used for imaging a mesh plate and a porcine mandible phantom. Subtraction images between FIP and BIP images were synthesized in four steps: correcting horizontal and vertical direction, rotation, enlargement ratio, and enlargement ratio into 12 blocks. Variance of the pixel value on the subtraction images at each step was compared to evaluate the alignment of FIP and BIP images. RESULTS: The variance of the pixel values in the subtraction images was gradually and significantly decreased by each step of image processing (P < 0.01), indicating that the degree of alignment of FIP and BIP images improved during the image processing. CONCLUSION: The present study revealed that it is possible to synthesize more precise DIP images using an additional four-step image processing technique.

Reduction of scratch or dirt artifacts on intraoral radiographs using dual imaging plates in image processing.

OBJECTIVES: Artifacts including scratches and dirt artifacts on the digital intraoral radiographs finally contribute to making inaccurate diagnoses. The aim of this study was to reduce the incidence of artifacts using dual imaging plates (DIPs) in imaging processing. METHODS: Conventional X-rays were taken of a porcine mandible embedded in acrylic resin using a DIP which consists of a front IP (FIP) and a back IP (BIP) with some scratches and dirt. The two images of the FIP and BIP were then synthesized and averaged to obtain a conventional DIP image. The following image processing method was used to make a DIP with artifact reduction (DIP+AR) image. A subtraction image of the FIP and BIP was constructed and the standard deviation (SD) was calculated. If the pixel value was over 3SD on the subtraction images, the pixel value of the DIP was swapped with the value on the opposite side of the non-artifact pixel. The conventional and DIP+AR images were also subjectively evaluated. RESULTS: Image processing to create a DIP+AR image was able to reduce the number of artifacts. Medians of number of artifacts evaluated were 2.00 [interquartile range (IQR), 2.50] in DIP images and 0.67 (IQR, 1.29) in DIP+AR images, indicating a significant reduction of number of artifacts in DIP+AR images. CONCLUSIONS: DIP+AR image processing can reduce the incidence of artifacts caused by scratches and dirt, and could extend the lifespan of the IP and contribute accurate diagnosis in oral radiology.

Bone marrow-derived dedifferentiated fat cells exhibit similar phenotype as bone marrow mesenchymal stem cells with high osteogenic differentiation and bone regeneration ability.

BACKGROUND: Mesenchymal stem cells (MSCs) are known to have different differentiation potential depending on the tissue of origin. Dedifferentiated fat cells (DFATs) are MSC-like multipotent cells that can be prepared from mature adipocytes by ceiling culture method. It is still unknown whether DFATs derived from adipocytes in different tissue showed different phenotype and functional properties. In the present study, we prepared bone marrow (BM)-derived DFATs (BM-DFATs), BM-MSCs, subcutaneous (SC) adipose tissue-derived DFATs (SC-DFATs), and adipose tissue-derived stem cells (ASCs) from donor-matched tissue samples. Then, we compared their phenotypes and multilineage differentiation potential in vitro. We also evaluated in vivo bone regeneration ability of these cells using a mouse femoral fracture model. METHODS: BM-DFATs, SC-DFATs, BM-MSCs, and ASCs were prepared from tissue samples of knee osteoarthritis patients who received total knee arthroplasty. Cell surface antigens, gene expression profile, and in vitro differentiation capacity of these cells were determined. In vivo bone regenerative ability of these cells was evaluated by micro-computed tomography imaging at 28 days after local injection of the cells with peptide hydrogel (PHG) in the femoral fracture model in severe combined immunodeficiency mice. RESULTS: BM-DFATs were successfully generated at similar efficiency as SC-DFATs. Cell surface antigen and gene expression profiles of BM-DFATs were similar to those of BM-MSCs, whereas these profiles of SC-DFATs were similar to those of ASCs. In vitro differentiation analysis revealed that BM-DFATs and BM-MSCs had higher differentiation tendency toward osteoblasts and lower differentiation tendency toward adipocytes compared to SC-DFATs and ASCs. Transplantation of BM-DFATs and BM-MSCs with PHG enhanced bone mineral density at the injection sites compared to PHG alone in the mouse femoral fracture model. CONCLUSIONS: We showed that phenotypic characteristics of BM-DFATs were similar to those of BM-MSCs. BM-DFATs exhibited higher osteogenic differentiation potential and bone regenerative ability compared to SC-DFATs and ASCs. These results suggest that BM-DFATs may be suitable sources of cell-based therapies for patients with nonunion bone fracture.

Collagen type I-based recombinant peptide promotes bone regeneration in rat critical-size calvarial defects by enhancing osteoclast activity at late stages of healing.

Introduction: We recently demonstrated the bone-forming potential of medium-cross-linked recombinant collagen peptide (mRCP) in animal models of bone defects. However, these studies were limited to a 4-week observation period; therefore, in the present study, we aimed to further evaluate mRCP as a suitable bone graft material for the alveolar cleft by analyzing its bone-forming potential, osteogenic-inducing ability, and biodegradation over an extended period of 12 weeks, using a rat critical-size calvarial defect model. Methods: Using Sprague-Dawley rats, we created critical-size calvarial defects through a surgical procedure. The defects were then filled with 3 mg of mRCP (mRCP group) or 18 mg of Cytrans® (CA) granules, which has a carbonate apatite-based composition resembling natural bone, was used as a reference material (CA group). For negative control, the defects were left untreated. Bone volume, total bone volume (bone volume including CA granules), and bone mineral density (BMD) in the defect were assessed using micro-computed tomography (µ-CT) at 0, 4, 8, and 12 weeks after implantation. Using histomorphometric analyses of hematoxylin and eosin (H&E)-stained sections, we measured the amount of newly formed bone and total newly formed bone (new bone including CA granules) in the entire defect site, as well as the amount of newly formed bone in the central side, two peripheral sides (left and right), periosteal (top) side, and dura mater (bottom) side. In addition, we measured the amount of residual bone graft material in the defect. Osteoclasts and osteoblasts in the newly formed bone were detected using tartrate-resistant acid phosphatase (TRAP) and alkaline phosphatase (ALP) staining, respectively. Results: Bone volume in the mRCP group increased over time and was significantly larger at 8 and 12 weeks after surgery than at 4 weeks. The bone volume in the mRCP group was greater than that of the CA and control groups at 4, 8, and 12 weeks after implantation, and while the total bone volume was greater in the CA group after 4 and 8 weeks, the mRCP group had comparable levels of total bone volume to that of the CA group at 12 weeks after implantation. The BMD of the mRCP group reached similar levels to native calvaria bone at the same time point. H&E-stained sections revealed a larger amount of newly formed bone 12 weeks after implantation in the mRCP group compared to that of the CA and control groups. The total newly formed bone at 12 weeks after implantation was on par with that in the CA group. Furthermore, at the defect site, the area of newly formed bone was larger on the peripheral and dura mater sides. Notably, the number of osteoclasts in the mRCP group was higher than in the CA and control groups and peaked 8 weeks after implantation, which coincided with the timing of the greatest resorption of mRCP. Although the ALP-positive area was greater in the mRCP group compared to other groups, we did not detect any significant changes in the number of osteoblasts over time. Conclusion: This study demonstrated the bone-forming potential of mRCP over an extended period of 12 weeks, suggesting that mRCP sufficiently resists resorption to promote bone formation through induction of osteoclast activation in the late stages of the healing period.

Preliminary evaluation of dual imaging plate intraoral radiography.

PURPOSE: This study evaluated the contrast-to-noise ratio (CNR), spatial resolution, and subjective quality of dual imaging plates (DIP) intraoral radiography. METHODS: The DIP and conventional single IP (CSIP) methods both used YCR DT-1 imaging plates (Yoshida Co.). The DIP, comprising a front IP (FIP) and back IP (BIP), was constructed. DIP images were synthesized from the FIP and BIP images. An aluminum step phantom was used to measure the CNR. A line pair gauge was used to measure the spatial imaging resolution. A phantom comprising a porcine mandible embedded in acrylic resin was used for subjective evaluation. RESULTS: The CNR of the DIP image was 32% higher than that of the FIP image. The spatial resolution achieved using the FIP, DIP, and CSIP was highly comparable except above 4 line pairs/mm, where that of the CSIP was highest. In subjective evaluation, the noise in the DIP images was significantly lower than in those obtained using the FIP and CSIP. CONCLUSION: The CNR of the DIP was higher than that of the FIP. The decrease in spatial resolution of the DIP was limited. The subjective image quality of the DIP was higher than that of the FIP.

Appropriate pore size for bone formation potential of porous collagen type I-based recombinant peptide.

Introduction: In this study, we developed porous medium cross-linked recombinant collagen peptide (mRCP) with two different ranges of interconnected pore sizes, Small-mRCP (S-mRCP) with a range of 100-300 µm and Large-mRCP (L-mRCP) with a range of 200-500 µm, to compare the effect of pore size on bone regeneration in a calvarial bone defect. Methods: Calvarial bone defects were created in Sprague-Dawley rats through a surgical procedure. The rats were divided into 2 groups: S-mRCP implanted group and L-mRCP implanted group. The newly formed bone volume and bone mineral density (BMD) was evaluated by micro-computed tomography (micro-CT) immediately after implantation and at 1, 2, 3, and 4 weeks after implantation. In addition, histological analyses were carried out with hematoxylin and eosin (H&E) staining at 4 weeks after implantation to measure the newly formed bone area between each group in the entire defect, as well as the central side, the two peripheral sides (right and left), the periosteal (top) side and the dura matter (bottom) side of the defect. Results: Micro-CT analysis showed no significant differences in the amount of bone volume between the S-mRCP and L-mRCP implanted groups at 1, 2, 3 and 4 weeks after implantation. BMD was equivalent to that of the adjacent native calvaria bone at 4 weeks after implantation. H&E images showed that the newly formed bone area in the entire defect was significantly larger in the S-mRCP implanted group than in the L-mRCP implanted group. Furthermore, the amount of newly formed bone area in all sides of the defect was significantly more in the S-mRCP implanted group than in the L-mRCP implanted group. Conclusion: These results indicate that the smaller pore size range of 100-300 µm is appropriate for mRCP in bone regeneration.