Analysis of the sublingual artery using contrast-enhanced computed tomography.

INTRODUCTION: This in vivo study aimed to clarify the position of the sublingual artery (SLA) relative to the mandibular bone and to infer the potential risk for injury during dental implant surgery. METHODS: Contrast-enhanced computed tomography images of the mouth of 50 edentulous patients (100 sides) treated at Tokushima University Hospital were reviewed. Curved planar reconstructed images perpendicular to the alveolar ridge were processed and classified into molar, premolar, canine, and incisor regions. The SLA and its branches were identified, and the distance from the mandible to the SLA was measured. RESULTS: The SLA was located close to the mandible (<2 mm) in the molar, premolar, canine, and incisor segments in 12.0% (95% confidence interval 5.6%-18.4%), 20.6% (12.6%-28.7%), 30.5% (21.3%-39.8%), and 41.8% (28.8%-54.9%) cases, respectively. The SLA was located within ±3 mm craniocaudally to the upper wall of the mandibular canal in the molar and premolar regions in 50% of cases and within ±5 mm craniocaudally to the mylohyoid ridge in the canine and incisor regions in the other cases, with no sex or age-related differences. The vertical distance from the alveolar ridge to the SLA was influenced by sex and age owing to alveolar resorption, indicating that the alveolar ridge is not a reliable reference for predicting SLA position. CONCLUSIONS: As the risk of SLA injury always exist during dental implant placement and there is no way to confirm the SLA pathways in a patient, clinicians must avoid injuring the sublingual soft tissue.

Association of PD-L1 and ZEB-1 expression patterns with clinicopathological characteristics and prognosis in oral squamous cell carcinoma.

Programmed cell death-1 (PD-1) and its ligand programmed cell death 1 ligand 1 (PD-L1) are immune checkpoint inhibitors that play an important role in the host immune avoidance mechanism of tumors. The relationship between PD-L1 expression and malignancy has been reported in various types of cancer, such as lung and gastric cancer. In addition, epithelial-mesenchymal transition (EMT) of cancer cells is deeply involved in the invasion and metastasis of cancer. It has been reported that zinc finger E-box binding homeobox 1 (ZEB-1), an EMT inducer, contributes to metastasis in pancreatic and colon cancer. The present study aimed to investigate the relationship between the expression patterns of two markers, PD-L1 and ZEB-1, and clinicopathological characteristics and prognosis of oral squamous cell carcinoma (OSCC). Biopsy or surgical excision specimens from 169 patients with OSCC were used in the present study. Immunohistochemical staining with monoclonal anti-PD-L1 antibody and anti-ZEB-1 antibody was conducted. Cases with >1% tumor cells positive for PD-L1 and those with >10% tumor cells positive for ZEB-1 were considered positive, respectively. The findings revealed that individual expression of PD-L1 and ZEB-1 in OSCC was not associated with tumor size, degree of differentiation or Yamamoto-Kohama invasion pattern classification. However, co-expression of PD-L1 and ZEB-1 was associated with higher cervical lymph node metastasis and a lower survival rate. In conclusion, the results of the present study indicated that co-expression of PD-L1 and ZEB-1 could serve as a potential marker for the prognosis of patients with OSCC.

Histological comparison of three apatitic bone substitutes with different carbonate contents in alveolar bone defects in a beagle mandible with simultaneous implant installation.

Since bone apatite is a carbonate apatite containing carbonate in an apatitic structure, carbonate content may be one of the factors governing the osteoconductivity of apatitic bone substitutes. The aim of this study was to evaluate the effects of carbonate content on the osteoconductivity of apatitic bone substitutes using three commercially available bone substitutes for the reconstruction of alveolar bone defects of a beagle mandible with simultaneous dental implant installation. NEOBONE, Bio-Oss, and Cytrans that contain 0.1, 5.5, and 12.0 mass% of carbonate, respectively, were used in this study. The amount of newly formed bone in the upper portion of the alveolar bone defect of the beagle's mandible was 0.7, 6.6, and 39.4% at 4 weeks after surgery and 4.7, 39.5, and 75.2% at 12 weeks after surgery for NEOBONE, Bio-Oss, and Cytrans, respectively. The results indicate that bone-to-implant contact ratio was the largest for Cytrans. Additionally, the continuity of the alveolar ridge was restored in the case of Cytrans, whereas the continuity of the alveolar ridge was not sufficient when using NEOBONE and Bio-Oss. Both Cytrans and Bio-Oss that have a relatively larger carbonate content in their apatitic structure was resorbed with time. We concluded that carbonate content is one of important factors governing the osteoconductivity of apatitic bone substitutes.

Application of low-crystalline carbonate apatite granules in 2-stage sinus floor augmentation: a prospective clinical trial and histomorphometric evaluation.

PURPOSE: The purpose of this study was to elucidate the efficacy and safety of carbonate apatite (CO3Ap) granules in 2-stage sinus floor augmentation through the radiographic and histomorphometric assessment of bone biopsy specimens. METHODS: Two-stage sinus floor augmentation was performed on 13 patients with a total of 17 implants. Radiographic assessment using panoramic radiographs was performed immediately after augmentation and was also performed 2 additional times, at 7±2 months and 18±2 months post-augmentation, respectively. Bone biopsy specimens taken from planned implant placement sites underwent micro-computed tomography, after which histological sections were prepared. RESULTS: Postoperative healing of the sinus floor augmentation was uneventful in all cases. The mean preoperative residual bone height was 3.5±1.3 mm, and this was increased to 13.3±1.7 mm by augmentation with the CO3Ap granules. The mean height of the augmented site had decreased to 10.7±1.9 mm by 7±2 months after augmentation; however, implants with lengths in the range of 6.5 to 11.5 mm could still be placed. The mean height of the augmented site had decreased to 9.6±1.4 mm by 18±2 months post-augmentation. No implant failure or complications were observed. Few inflammatory cells or foreign body giant cells were observed in the bone biopsy specimens. Although there were individual differences in the amount of new bone detected, new bone was observed to be in direct contact with the CO3Ap granules in all cases, without an intermediate layer of fibrous tissue. The amounts of bone and residual CO3Ap were 33.8%±15.1% and 15.3%±11.9%, respectively. CONCLUSIONS: In this first demonstration, low-crystalline CO3Ap granules showed excellent biocompatibility, and bone biopsy showed them to be replaced with bone in humans. CO3Ap granules are a useful and safe bone substitute for two-stage sinus floor augmentation.Trial Registration: ICTRP Identifier: JPRN-UMIN000019281.

Maxillary Sinus Floor Augmentation Using Low-Crystalline Carbonate Apatite Granules With Simultaneous Implant Installation: First-in-Human Clinical Trial.

PURPOSE: Carbonate apatite (CO3Ap), an inorganic component of human bone, can be fabricated in chemically pure form from calcium carbonate block via a dissolution-precipitation reaction. A first-in-human clinical trial was conducted in which low-crystalline CO3Ap granules were evaluated for safety and efficacy in sinus floor augmentation and simultaneous implant installation. MATERIALS AND METHODS: Procedures were performed in 8 patients (9 implants) with 2 granule sizes: small (300 to 600 µm) and medium (600 to 1,000 µm). Panoramic radiographic assessment was performed immediately after augmentation, 7 ± 2 months after augmentation, 6 ± 2 months after prosthetic loading, and 12 ± 2 months after prosthetic loading. RESULTS: Postoperative healing was uniformly uneventful, with no abnormal bleeding, pain, or swelling, and all implants achieved successful osseointegration. The mean residual maxillary molar bone height was 5.2 ± 0.8 mm preoperatively and increased to 14.0 ± 1.9 mm after augmentation. Implants 9.0 to 11.5 mm in length were placed. The post-augmentation height decreased to 12.4 ± 1.3 mm at 7 ± 2 months; after prosthetic loading, it decreased to 11.9 ± 0.8 mm at 6 ± 2 months and 11.7 ± 0.6 mm at 12 ± 2 months. No abnormal bone resorption of the augmented areas was observed, and bone height supporting the implants was maintained. The overall implant survival rate was 100%, with no implant failures or complications during the first year. CONCLUSIONS: Low-crystalline CO3Ap granules were useful and safe for sinus floor augmentation and simultaneous implant installation, providing a promising bone substitute for dental implant surgery.

Surface plasma treatment and phosphorylation enhance the biological performance of poly(ether ether ketone).

Poly(ether ether ketone) (PEEK) has emerged as an alternative endosseous material to metal implants mainly because of its lack of allergic sensitivity and radiolucency, while maintaining similar mechanical properties with bone. However, a disadvantage of PEEK is its weak osseointegration ability compared with metal implants. To overcome this, we prepared a phosphate group-modified PEEK by plasma treatment and subsequent phosphorylation reaction. Plasma treatment and phosphate modification of PEEK changed its hydrophobic surface to a hydrophilic surface while maintaining the original surface topography and roughness. Phosphate modification increased the bioactivity of rat bone marrow stromal cells (BMSCs), including proliferation, alkaline phosphatase activity, and bone-like nodule formation; however, this effect was negligible in plasma-treated PEEK. In addition, phosphate modification attenuated the phenotypic polarization of lipopolysaccharide-primed RAW264.7 macrophages to an inflammatory phenotype, based on the finding that macrophages on phosphate-modified PEEK produced decreased levels of the inflammatory cytokine and increased levels of the anti-inflammatory cytokine. Finally, in an animal study, phosphate-modified PEEK exhibited a doubled pullout force from the femur bone cavity compared with bare PEEK. Thus, we conclude that phosphate modification can significantly improves the implant-bone bonding strength of PEEK by enhancing BMSCs activity and reducing excessive inflammation.

Synergistic effect of surface phosphorylation and micro-roughness on enhanced osseointegration ability of poly(ether ether ketone) in the rabbit tibia.

This study was aimed to investigate the osseointegration ability of poly(ether ether ketone) (PEEK) implants with modified surface roughness and/or surface chemistry. The roughened surface was prepared by a sandblast method, and the phosphate groups on the substrates were modified by a two-step chemical reaction. The in vitro osteogenic activity of rat mesenchymal stem cells (MSCs) on the developed substrates was assessed by measuring cell proliferation, alkaline phosphatase activity, osteocalcin expression, and bone-like nodule formation. Surface roughening alone did not improve MSC responses. However, phosphorylation of smooth substrates increased cell responses, which were further elevated in combination with surface roughening. Moreover, in a rabbit tibia implantation model, this combined surface modification significantly enhanced the bone-to-implant contact ratio and corresponding bone-to-implant bonding strength at 4 and 8 weeks post-implantation, whereas modification of surface roughness or surface chemistry alone did not. This study demonstrates that combination of surface roughness and chemical modification on PEEK significantly promotes cell responses and osseointegration ability in a synergistic manner both in vitro and in vivo. Therefore, this is a simple and promising technique for improving the poor osseointegration ability of PEEK-based orthopedic/dental implants.

Effect of micro-roughening of poly(ether ether ketone) on bone marrow derived stem cell and macrophage responses, and osseointegration.

Poly(ether ether ketone) (PEEK) has emerged as a candidate to replace metal implants because of its satisfactory mechanical properties, radiolucency, and lack of metal allergy. However, PEEK lacks osseointegration ability limiting its clinical applications. To overcome this problem, we prepared PEEK with a micro-rough surface using the sandblast method to modulate its osseointegration property; the sandblast method is simple, cost-effective, and is already applied to clinical metal implants. The surface roughness of the sandblasted PEEK was about 2.3 µm, whereas that of mirror-polished PEEK was 0.06 µm. Rat bone marrow-derived mesenchymal stem cells (RMSCs) showed higher proliferation, osteocalcin (OC) expression and bone-like nodule formation on micro-roughened PEEK compared with those cultured on mirror-polished PEEK, suggesting that micro-roughening facilitated RMSCs proliferation and differentiation. The micro-roughened surface slightly mitigated secretion of inflammatory C-C motif chemokine 2 (CCL-2) from lipopolysaccharide (LPS)-stimulated macrophages, but not of tumor necrosis factor α (TNFα) and interleukin-6 (IL-6). Finally, to compare osseointegration, specimens were implanted in rat femur bone marrow cavities, and then the pull-out force was measured. The pull-out force of micro-roughened PEEK was about four times higher than that of the mirror-polished PEEK. These results showed that micro-roughening of PEEK using the sandblast method was able to improve osseointegration, partly through elevating proliferation and differentiation of RMSCs.

A novel GDNF-inducible gene, BMZF3, encodes a transcriptional repressor associated with KAP-1.

The Krüppel-associated box (KRAB)-containing zinc finger proteins (ZFPs) comprise the largest family of zinc finger transcription factors that function as transcriptional repressors. In the study of glial cell line-derived neurotrophic factor (GDNF)-RET signaling, we have identified bone marrow zinc finger 3 (BMZF3), encoding a KRAB-ZFP, as a GDNF-inducible gene by differential display analysis. The expression of BMZF3 transcripts in the human neuroblastoma cell line TGW increased 1h after GDNF stimulation, as determined by Northern blotting and quantitative reverse-transcriptase polymerase chain reaction. The BMZF3 possesses transcriptional repressor activity in the KRAB domain. BMZF3 interacts with a co-repressor protein, KRAB-associated protein 1 (KAP-1), through the KRAB domain and siRNA-mediated knockdown of KAP-1 abolished the transcriptional repressor activity of BMZF3, indicating that KAP-1 is necessary for BMZF3 function. Furthermore, siRNA-mediated silencing of BMZF3 inhibited cell proliferation. These findings suggest that BMZF3 is a transcriptional repressor induced by GDNF that plays a role in cell proliferation.

Identification of a novel glial cell line-derived neurotrophic factor-inducible gene required for renal branching morphogenesis.

In the developing kidney, activation of the rearrangement during transfection tyrosine kinase by glial cell line-derived neurotrophic factor (GDNF) is required for normal branching of the ureteric bud epithelium [corrected]. By differential display analysis we identified a novel GDNF-inducible gene (named GZF1) with a BTB/POZ (broad complex, tramtrack, and bric-a-brac)/(poxvirus and zinc finger) domain and 10 tandemly repeated zinc finger motifs. The up-regulation of the GZF1 gene showed two peaks at 1 h and 24-48 h after GDNF stimulation by Northern blotting. The late induction was also found at protein levels by Western blotting with anti-GZF1 antibody. As observed for other proteins with the BTB/POZ domain, the GZF1 protein had strong transcriptional repressive activity. Intriguingly, its expression was detected at high levels in branching ureteric buds and collecting ducts of mouse metanephric kidney in which RET was also expressed. Antisense phosphorothioated oligodeoxynucleotides of the GZF1 gene markedly impaired the ureteric bud branching in the metanephric organ culture, suggesting that the induction of GZF1 expression via the GDNF/RET signaling system is required for renal branching morphogenesis.