3D-printed custom tray for maxillofacial implant assisted partial denture.

This technique presents a new fabrication workflow for a three-dimensional (3D) printed custom tray, which duplicates the morphology of the treatment denture for maxillofacial prostheses using an intraoral scanner, computer-aided design (CAD) software, and a 3D printer. A 70-year-old man underwent reconstruction of segmental mandibulectomy for mandibular osteoblastoma, followed by implant placement and secondary surgery. During the surgical treatment, a treatment denture was fabricated to restore oral function and determine the morphology of the definitive denture. To create the definitive denture with the same morphology as the treatment denture a custom tray was fabricated with the denture morphology after chairside adjustments. The oral cavity was scanned using an intraoral scanner, and the data acquired were imported into general-purpose CAD software, adjusted, and imported into a 3D printer to produce the custom tray. This was fitted into the patient's mouth without any issues, and closed tray impressions were made with impression caps for the locator attachments on the implant body. The morphology of the treatment denture was replicated in the definitive denture by making a silicon impression of the cameo surface at the fabrication of the cast after impression making. In this technique, the morphology of the treatment denture was transferred accurately to the definitive implant partial denture by leveraging existing digital technology. This method represents a practical approach for partial denture fabrication, including maxillofacial defects with complex denture configurations.

Capability of new bone formation with a mixture of hydroxyapatite and beta-tricalcium phosphate granules.

OBJECTIVES: The aim of this experimental study was to test a mixture of hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP) granules inserted in cranial defects in rabbits, by the evaluation of the hard tissues volume, new bone formation, and residual graft after 4 and 8 weeks. MATERIAL AND METHODS: Two defects of 8 mm diameter were created at the calvarial bone of 24 Japanese white rabbits for a total of 48 defects. Four groups were created: defects filled with a mixture of HA and beta-TCP granules (test A), defects filled with HA alone (test B), defects filled with beta-TCP (test C), and empty defects (control). Hard tissues volume (remaining graft + new bone) was evaluated by µ-CT and new bone (NB) and remaining graft (RG) percentages were evaluated by histomorphometry. The animals were sacrificed at 4 or 8 weeks postoperatively. RESULTS: The test groups A, B, and C showed a significant higher total volume compared with controls at 4 and 8 weeks (P < 0.05). Regarding the percentages of NB and RG at 4 and 8 weeks, no significant differences were detected (P > 0.05). When comparing 4 and 8 weeks, test group A showed a significant increase in new bone formation. At both 4 and 8 weeks, no group showed significant differences in NB (P > 0.05). At 8 weeks, test group B had more RG than test group A. CONCLUSIONS: The novel mixture could maintain the volume of the grafted area compared with that with intervention, and in a similar way compared with HA.

Efficacy of a novel membrane comprising a copolymer of L-lactic acid and glycolic acid in osteoblasts in vitro.

In guided bone regeneration (GBR), a barrier membrane is applied to provide a space for bone regeneration to promote cell adhesion, cell proliferation, and bone regeneration by inducing cell migration to the surface of the bone-deficient site. We prepared a non-woven absorbable membrane for GBR comprised of a copolymer of L-lactic acid and glycolic acid (PLLGA) using the dry spinning method. A thin and dense membrane comprising unsintered hydroxyapatite (uHA) and poly-L-lactic acid (PLLA) was used for comparison. Osteoblast TMS-12 cells were seeded onto the membranes, and cell adhesion and proliferation rates were examined. Calcification levels were quantified by Alizarin Red S staining after cell culture in calcification induction medium. Osteoblastic gene expression was examined by RT-PCR. Cell adhesion and proliferation rates and calcification on PLLGA membranes were significantly higher than those on uHA/PLLA membranes. PLLGA membranes upregulated osteogenic gene expression compared to on uHA/PLLA membranes. Non-woven PLLGA membranes may be useful in GBR for promoting bone formation and maturation.

Autologous micrografts from the palatal mucosa for bone regeneration in calvarial defects in rats: a radiological and histological analysis.

BACKGROUND: The application of dental implants is often restricted by bone volume. In such cases, bone grafts are required, although bone graft materials have some disadvantages. Therefore, other effective approaches are needed. Our previous study showed that the autologous micrograft, a dissociated cell suspension made out of palatal connective tissue grafts, promoted bone-marrow cell proliferation and differentiation under osteogenic conditions. In this study, we aimed to evaluate the effects of dissociated soft-tissue suspensions relevant to bone regeneration in animal model. MATERIAL AND METHODS: Twelve-week-old male Wistar rats were used in the study. Defects were created in rat calvaria, and were filled with hydrogel containing either dissociated soft-tissue suspension (test) or sucrose (control). The new bone formation was evaluated at 1 and 2 weeks after surgery (n = 16) by radiological and histological analysis. RESULTS: The conducted radiological analysis showed that the new bone volume was significantly greater in the dissociated soft-tissue suspension group. This finding was further confirmed by the conducted histological analysis. CONCLUSIONS: The dissociated mucosa tissue suspension enhanced bone regeneration in vivo; thus, it is a promising potential method to aid the successful application for bone augmentation in the implant practice.

A novel hydroxyapatite fiber material for the regeneration of critical-sized rabbit calvaria defects.

Hydroxyapatite (HA) [Ca10 (PO4)6 (OH)2] has a high degree of chemical similarity with the mineral composition of animal bone. Hydroxyapatite fiber scaffold (HAF) is a biological material with a highly interconnected porous structure. We aimed to study the physical and biological characteristics of HAF and compare the osteogenic effects of HAF, natural osteogenic materials (NOM), and carbonate apatite (CO3Ap-DP) in the parietal defects of a rabbit's skull. X-ray analysis and histological assessment showed that HAF followed a trend of early initial osteogenesis and bone trabecular structure formation, especially at the cortical bone portion.Compared to the other two materials, HAF was more absorptive. Results indicated that HAF had the same osteoconductive and new bone formation properties as NOM and CO3Ap-DP. These findings will provide options for future material development and novel protocols for use in surgeries, ultimately leading to better patient outcomes.

CUBIC-Cloud provides an integrative computational framework toward community-driven whole-mouse-brain mapping.

Recent advancements in tissue clearing technologies have offered unparalleled opportunities for researchers to explore the whole mouse brain at cellular resolution. With the expansion of this experimental technique, however, a scalable and easy-to-use computational tool is in demand to effectively analyze and integrate whole-brain mapping datasets. To that end, here we present CUBIC-Cloud, a cloud-based framework to quantify, visualize, and integrate mouse brain data. CUBIC-Cloud is a fully automated system where users can upload their whole-brain data, run analyses, and publish the results. We demonstrate the generality of CUBIC-Cloud by a variety of applications. First, we investigated the brain-wide distribution of five cell types. Second, we quantified Aß plaque deposition in Alzheimer's disease model mouse brains. Third, we reconstructed a neuronal activity profile under LPS-induced inflammation by c-Fos immunostaining. Last, we show brain-wide connectivity mapping by pseudotyped rabies virus. Together, CUBIC-Cloud provides an integrative platform to advance scalable and collaborative whole-brain mapping.

Bone augmentation ability of autogenous bone graft particles with different sizes: a histological and micro-computed tomography study.

OBJECTIVES: The purpose of this study was to investigate the augmentation process and ability of autogenous bone graft particles of two different sizes in a vertical augmentation chamber. MATERIAL AND METHODS: The cranial bones of 24 rabbits were used. Two polytetrafluoroethylene chambers were filled with harvested bone from tibia with small bone (SB; 150-400 microm) and large bone (LB; 1.0-2.0 mm) of the same weight. Animals were sacrificed after 1, 2, 4 and 8 weeks. The samples were analyzed by micro-computed tomography (micro-CT) for quantitative analysis, and embedded in polyester resin as non-decalcified specimens for histological analysis. Total bone volume (TBV), bone height (BH) and distribution of bone structure were calculated by micro-CT. RESULTS: Micro-CT evaluation and histology revealed a significant difference between the investigated specimens. TBV and BH of SB decreased to about 50% of the initial situation, and there was a statistically significant difference between 1 and 8 weeks. In contrast, TBV and BH of LB were almost retained at all experimental time points. Significant differences in TBV and BH were also observed between LB and SB at 8 weeks. Bone volume of SB decreased predominantly in the upper half of the chamber at 4 and 8 weeks. In the histological observations, SB showed favorable new bone formation and rapid bone resorption in a time-dependent manner during the entire experimental period. However, LB exhibited favorable morphological stability and continued new bone formation. CONCLUSION: SB follows a smooth osteogenic process, whereas it is not effective in volume augmentation. LB is superior to SB in augmentation ability.

The Effect of Dissociated Soft Tissue on Osteogenesis: A Preliminary In Vitro Study.

PURPOSE: The purpose of this in vitro study was to examine the effect of dissociated soft tissue on bone marrow cell proliferation and differentiation under osteogenic conditions. MATERIALS AND METHODS: Rat bone marrow cells were cultured to assess the stimulation of cell proliferation and differentiation. Harvested palatal mucosa was dissociated using a device (Rigenera; Human Brain Wave) and the dissociated soft tissue was cultured with rat bone marrow cells. Cell proliferation, differentiation, and mineralized nodule formation were assessed after 2 or 5 days of culturing. Bone marrow cell proliferation was assessed by quantifying the absorbance of a water-soluble tetrazolium salt using a cell proliferation assay kit. Bone marrow cell differentiation was assessed by alkaline phosphatase staining and real-time polymerase chain reaction. Mineralized nodule formation was assessed by Alizarin red staining. RESULTS: At day 2, cell proliferation, osteoblast specific gene expression, and mineralized nodule formation were significantly higher in the experimental group than in the control group. Alkaline phosphatase staining was also higher in the experimental group on day 2. Mineralized nodule formation area and osteoblast specific gene expression were also statistically higher in the experimental group on day 5. CONCLUSION: This study demonstrates that dissociated soft tissue elevates bone marrow cell proliferation and differentiation under osteogenic conditions.

Osteoconductive potential of a hydroxyapatite fiber material with magnesium: In vitro and in vivo studies.

Despite the benefits of hydroxyapatite fiber (HAf) as a synthetic bone substitute, materials capable of faster bone regeneration would be more preferable. In this study, effects of HAf with magnesium (Mg-HAf) on bone regeneration were evaluated. In vitro, levels of osteogenic genes were significantly higher in bone marrow cells cultured with Mg-HAf than in those cultured with HAf alone. Moreover, effects of HAf only (control) and 5.7 mol% Mg-HAf on the cranial bones of Japanese white rabbits were evaluated. MicroCT imaging and histology indicated significant differences between the control and Mg-HAf groups. Significantly higher new bone volumes and percentages were observed in the Mg-HAf group than in controls at 4 and 8 weeks (p<0.05); the newly formed bone was more mature in the Mg-HAf group than in controls. These results indicated that Mg-HAf can enhance osteogenic differentiationrelated gene expression and promote rapid bone formation and maturation.

[Molecular Mechanisms of Circadian Rhythm and Sleep Homeostasis].

Sleep-wake cycle is controlled by the interplay between circadian rhythm and sleep homeostasis. Genetic studies, through the discovery of mutants with altered sleep-wake behaviors, have explored the molecular components that regulate our daily rhythms. In mammalian circadian clocks, negative-feedback loops composed of a set of transcription activators and inhibitors generate a cell-autonomous oscillation of transcriptional activity. Recent studies further discovered that such transcriptional feedback is controlled through post-translational modifications for the fine-tuning of the oscillation period. Compared to circadian clocks, the canonical molecular model for sleep homeostasis is not established yet. However, recent advances in mammalian forward and reverse genetic studies discovered several genes that regulate sleep duration. Interestingly, these genes include ion channels and kinases, which potentially modify these channels. A part of sleep-related ion channels is involved in Ca2+-dependent hyperpolarization of the neuronal membrane potential. Computational models suggest that the hyperpolarization pathway underlies the firing patterns observed in the cortical pyramidal neurons during sleep. Thus, ion channels controlling the membrane potential of the cortical neurons may be involved in sleep homeostasis.

Evaluation of the Alteration of Occlusal Distribution in Unilateral Free-End and Intermediate Missing Cases.

The present study aimed to evaluate the effect of implant prostheses on the occlusal force and area as well as the distribution of occlusal loading in unilateral free-end and intermediate missing cases. Fourteen healthy subjects (7 free-end missing cases in the first and second molars and 7 intermediate missing cases in the first molar region) were included. Six months after the implant prosthesis was placed, an occlusal evaluation was performed with or without the implant superstructure by using Dental Prescale film and an occluder device. In free-end missing cases, the total occlusal force and area, implant-side occlusal force and area, and implant-side occlusal force and area of the residual natural teeth were significantly affected by the implant prostheses. In intermediate missing cases, the implant-side occlusal force of the residual natural teeth was significantly affected by the implant prostheses. In free-end missing cases, the proportions of implant-side occlusal force, non-implant-side occlusal force, and implant-side occlusal force of the residual natural teeth relative to the total occlusal force were significantly affected by the implant prostheses. In the intermediate missing cases, the proportion of the implant-side occlusal force of the residual natural teeth relative to the total occlusal force was significantly affected by the implant prostheses. The proportion of the occlusal area was also significantly affected. In free-end missing cases, implant prostheses significantly increased the occlusal force and area, which resulted in the proper occlusal distribution. In intermediate missing cases, an implant prosthesis may only improve the same-side occlusal loading of the natural teeth.

The effect of graft bone particle size on bone augmentation in a rabbit cranial vertical augmentation model: a microcomputed tomography study.

PURPOSE: The purpose of this study was to investigate the impact of graft bone particle size on autogenous bone graft augmentation in a vertical augmentation chamber model. MATERIALS AND METHODS: A total of 12 rabbits were used in this study. The donor bone particles were of different sizes: small (150 to 400 µm), large (1.0 to 2.0 mm), and a mixture comprising equal weights of both large and small bone particles. One type of bone graft material was placed into each of two polytetrafluoroethylene chambers that were implanted in the parietal bone of each rabbit's cranium. Animals were sacrificed 4 or 8 weeks after the grafting procedure. The recovered samples were analyzed by microcomputed tomography (micro-CT) for quantitative analysis. Total bone volume, bone height, and the distribution of bone structure were calculated by micro-CT. RESULTS: Micro-CT evaluations revealed that the bone grafts performed with large bone particles provided, statistically, the best outcome. Total bone volume and bone height decreased in a time-dependent manner, and there was a statistically significant reduction in total bone volume between 4 and 8 weeks in the group with the mixed bone particle sizes. CONCLUSION: Within the limitations of the present study, large bone graft particles provided the best preservation of total bone volume and bone height up to 8 weeks after grafting in an animal vertical augmentation model.

Evaluation of a biodegradable novel periosteal distractor.

UNLABELLED: We developed a new device composed of a thin biodegradable mesh (poly-L-lactide/hydroxyapatite composite) for distracting periosteum. The purpose of this study is to evaluate the effect of using this device as a periosteal distractor. MATERIALS AND METHODS: Eight Japanese male rabbits were divided into two groups according to time of sacrifice. The calvarial periosteum was elevated and one side of a biodegradable mesh was fixed to the bone surface with two titanium screws. Seven days after the surgery, an elevating screw was inserted into the other side of the mesh. Then, the calvarial periosteum was elevated at maximum 0.5 mm every 12 h for 5 days. The device was designed to distract the periosteum at different rates along its entire surface. At 4 and 6 weeks of the consolidation, the animals were sacrificed and newly formed bone was histologically and radiographically evaluated. RESULTS: The new device simplified periosteal distraction and reduced its invasiveness. Moreover, it successfully induced new bone formation from two sources; the periosteum and the underlying basal bone. Histomorphometric analysis of the distracted space showed that there is a relation between the rate of distraction and the amount of newly formed bone. We suggest that the optimal speed range for periosteal distraction in rabbit calvarial model could be less than 0.33 mm/day. CONCLUSIONS: The new device is slim, biodegradable and the procedure is simple. Thus, periosteal distraction with this device is potential for vertical and horizontal ridge augmentation in oral cavity.

Differentiation of bone marrow stromal cells into osteoblasts in a self-assembling peptide hydrogel: in vitro and in vivo studies.

A prerequisite of tissue engineering approaches with regard to autograft is a suitable scaffold that can harbor cells and signals. Conventionally, such scaffolds have been prepared as 3D scaffolds prefabricated from synthetic or natural biomaterials. RAD16 has been introduced as a new biomaterial, where synthetic peptides self-assemble to form a hydrogel. In this study, RAD16 was examined in terms of osteogenic efficacy and feasibility of ectopic mineralization. Two hundred and seventy-one RAD16 was cocultured with 1 × 10(6) bone marrow cells from the femurs of 6-week-old Wistar male rats in alpha minimum essential medium supplemented with or without dexamethasone. Second, the same volume of the RAD16 construct hosting the cells with or without hydroxyapatite (HA) particles was treated in the dexamethasone medium as well, prepared in a Teflon tube, and implanted subcutaneously. Cell proliferation was prominent in the RAD16 coculture with dexamethasone at 1 week and significantly decreased by 2 weeks, whereas the other combinations remained or inclined, and their osteogenic differentiation was accelerated up to 2 weeks, as seen in increasing alkaline phosphatase (ALP) activity and mRNAs of ALP, OPN, and OCN. The RAD16 implant prepared with HA particles allowed more osteoblast-like cells and blood cells to grow inside, which was accompanied by elevating OPN gene expression and the stronger peak of VEGF gene expression at 2 weeks. Furthermore, more OPN mRNA signal was detected around the RAD16 containing HA particles by 4 weeks. On the other hand, the RAD16 alone represented lower expression of OPN gene. During the experiment, however, no ectopic mineralization was observed in both groups. Conclusively, it was suggested that the RAD16 showed feasibility of serving as a matrix for osteogenic differentiation of cocultured bone marrow cells in vitro and in vivo. Proceeding of exploration and modification of RAD16 are continuously required for cell-based tissue engineering.