The Transoral Endoscope-Assisted Approach for Removal of a Dental Implant Displaced into the Maxillary Sinus: A Case Report and Review of the Literature.

Purpose: A dental implant displaced into the maxillary sinus can be removed transorally or transnasally. There is no report investigating any potential positional limitations by the transoral endoscope-assisted approach. The implant's location within the maxillary sinus was reviewed to clarify indications for this approach. Case report: A 36-year-old man was referred to us for removal of a dental implant displaced into the right maxillary sinus. The implant changed position preoperatively, but the transoral endoscope-assisted approach proved successful. Methods: A literature search through October 2020 was performed in PubMed for cases of implant removal from the maxillary sinus via transoral endoscope-assisted and transnasal endoscopic approaches. Results: Sixty-two prior cases were identified, 20 cases by the transoral endoscope-assisted approach and 43 cases by one or two transnasal endoscopic approaches, including one duplicate case. There were no cases in which the implant was not identified by the transoral endoscope-assisted approach, but two cases in which the implant had moved to an unfavorable location and was not identified by only the initial transnasal endoscopic approach. Conclusion: Clinicians can preferentially choose the transoral endoscope-assisted approach, considering the possibility of unfavorable repositioning of the displaced implant within the maxillary sinus.

Expression of Neurokinin B Receptor in the Gingival Squamous Cell Carcinoma Bone Microenvironment.

Gingival squamous cell carcinoma (SCC) frequently invades the maxillary or mandibular bone, and bone destruction is known as a key prognostic factor in gingival SCCs. Recently, Neurokinin 3 receptor (NK-3R), the receptor ligand for NK-3, which is a member of the tachykinin family expressed in the central nervous system, was identified through pathway analysis as a molecule expressed in osteoclasts induced by the hedgehog signal. Although the expression of NK-3R has been detected in osteoclast and SCC cells at the bone invasion front, the relationship between NK-3R expression and the prognosis of gingival SCC patients remains unclear. In the present study, we retrospectively reviewed 27 patients with gingival SCC who had undergone surgery with curative intent. Significantly higher NK-3R expression in tumor cells was found in a case of jawbone invasion than in a case of exophytic poor jawbone invasion. On the other hand, no significant association was observed between NK-3R tumor-positive cases and tumor size, TNM stage, or tumor differentiation. The survival rate tended to be lower in NK-3R tumor-positive cases, but not significantly. However, the disease-specific survival rate was significantly lower in patients with a large number of NK-3R-positive osteoclasts than in those with a small number of them at the tumor bone invasion front. Our results suggest that NK-3R signaling in the gingival SCC bone microenvironment plays an important role in tumor bone destruction and should be considered a potential therapeutic target in advanced gingival SCC with bone destruction.

Surgical resection for advanced bisphosphonate-related osteonecrosis of the jaw associated with fibrous dysplasia: a case report.

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is an adverse drug reaction represented by destruction and/or death of bone. Fibrous dysplasia (FD) is a rare bony disorder characterised by abnormal fibro-osseous tissue that has lowered resistance to infection. Effective treatments for BRONJ that follows FD are unclear. Here, we report that advanced BRONJ associated with FD was successfully treated by surgical resection. A 69-year-old woman, whose left maxillary bone showed a ground glass appearance on computed tomography (CT) images, was taking alendronate. At 1 year after teeth within the abnormal bone were extracted, exposed bone was observed in the extraction sites and CT images revealed separated sequestrums. Under the clinical diagnosis of Stage 2 BRONJ with FD, we performed not only sequestrectomy but also a partial resection of the FD. Thereafter, the healing was uneventful without recurrence. In conclusion, our case suggests that surgical resection is useful for advanced BRONJ associated with FD.

The Prognostic Implications of Bone Invasion in Gingival Squamous Cell Carcinoma.

BACKGROUND/AIM: This study evaluated the associations between bone invasion of gingival squamous cell carcinoma (SCC) and clinicopathological manifestations, and aimed to determine whether bone invasion is an independent prognostic factor in gingival SCC. PATIENTS AND METHODS: The study was a retrospective review of 78 patients with gingival SCC who underwent surgery with curative intent. The level of bone invasion was pathologically categorized as medullary, cortical or no bone invasion. RESULTS: Cortical and medullary bone invasion was present in 29 and 22 patients, respectively. There was a significant association between medullary bone invasion and tumor size (p=0.017), pathological N classification (p<0.001), differentiation (p=0.017) and lymphovascular invasion (p=0.007). Medullary bone invasion and lymphovascular invasion were independent predictors of reduced overall survival (p=0.015, 0.048); medullary bone invasion was also an independent predictor of reduced disease-specific survival (p=0.018). CONCLUSION: Pathologically-proven medullary bone invasion and lymphovascular invasion were found to be key prognostic factors in gingival SCC. The results suggest that it is necessary to consider adjuvant therapy in patients with medullary bone invasion.

Physiological role of urothelial cancer-associated one long noncoding RNA in human skeletogenic cell differentiation.

A vast number of long-noncoding RNAs (lncRNA) are found expressed in human cells, which RNAs have been developed along with human evolution. However, the physiological functions of these lncRNAs remain mostly unknown. In the present study, we for the first time uncovered the fact that one of such lncRNAs plays a significant role in the differentiation of chondrocytes and, possibly, of osteoblasts differentiated from mesenchymal stem cells, which cells eventually construct the human skeleton. The urothelial cancer-associated 1 (UCA1) lncRNA is known to be associated with several human malignancies. Firstly, we confirmed that UCA1 was expressed in normal human chondrocytes, as well as in a human chondrocytic cell line; whereas it was not detected in human bone marrow mesenchymal stem cells (hBMSCs). Of note, although UCA1 expression was undetectable in hBMSCs, it was markedly induced along with the differentiation toward chondrocytes, suggesting its critical role in chondrogenesis. Consistent with this finding, silencing of the UCA1 gene significantly repressed the expression of chondrogenic genes in human chondrocytic cells. UCA1 gene silencing and hyper-expression also had a significant impact on the osteoblastic phenotype in a human cell line. Finally, forced expression of UCA1 in a murine chondrocyte precursor, which did not possess a UCA1 gene, overdrove its differentiation into chondrocytes. These results indicate a physiological and important role of this lncRNA in the skeletal development of humans, who require more sustained endochondral ossification and osteogenesis than do smaller vertebrates.

Role of CCN2 in Amino Acid Metabolism of Chondrocytes.

CCN2/connective tissue growth factor (CTGF) is a multi-functional molecule that promotes harmonized development and regeneration of cartilage through its matricellular interaction with a variety of extracellular biomolecules. Thus, deficiency in CCN2 supply profoundly affects a variety of cellular activities including basic metabolism. A previous study showed that the expression of a number of ribosomal protein genes was markedly enhanced in Ccn2-null chondrocytes. Therefore, in this study, we analyzed the impact of CCN2 on amino acid and protein metabolism in chondrocytes. Comparative metabolome analysis of the amino acids in Ccn2-null and wild-type mouse chondrocytes revealed stable decreases in the cellular levels of all of the essential amino acids. Unexpectedly, uptake of such amino acids was rather enhanced in Ccn2-null chondrocytes, and the addition of exogenous CCN2 to human chondrocytic cells resulted in decreased amino acid uptake. However, as expected, amino acid consumption by protein synthesis was also accelerated in Ccn2-null chondrocytes. Furthermore, we newly found that expression of two genes encoding two glycolytic enzymes, as well as the previously reported Eno1 gene, was repressed in those cells. Considering the impaired glycolysis and retained mitochondrial membrane potential in Ccn2-null chondrocytes, these findings suggest that Ccn2 deficiency induces amino acid shortage in chondrocytes by accelerated amino acid consumption through protein synthesis and acquisition of aerobic energy. Interestingly, CCN2 was found to capture such free amino acids in vitro. Under physiological conditions, CCN2 may be regulating the levels of free amino acids in the extracellular matrix of cartilage.

Regulation of CCN1 via the 3'-untranslated region.

The 3'-untranslated region (UTR) is known to be a critical regulator of post-transcriptional events that determine the gene expression at the RNA level. The gene CCN1 is one of the classical members of the matricellular CCN family and is involved in a number of biological processes during mammalian development. In the present study, the 600-bp 3'-UTR of CCN1 was functionally characterized. Reporter gene analysis revealed that the entire 3'-UTR profoundly repressed gene expression in cis in different types of the cells, to which both the proximal and distal-halves of the 3'-UTR segments contributed almost equally. Deletion analysis of the 3'-UTR indicated a distinct functional element in the proximal half, whereas a putative target for microRNA-181s was predicted in silico in the distal half. Of note, the repressive RNA element in the proximal half was shown to be capable of forming a stable secondary structure. However, unexpectedly, a reporter construct with a tandem repeat of the predicted miR-181 targets failed to respond to miR-181a. In addition, the other major structured element predicted in the distal half was similarly characterized. To our surprise, the second element rather enhanced the reporter gene expression in cis. These results indicate the involvement of multiple regulatory elements in the CCN1 3'-UTR and suggest the complexity of the miRNA action as well as the 3'-UTR-mediated gene regulation.