Robotics in Dentistry : A Narrative Review

Background: Robotics is progressing rapidly. The aim of this study was to provide a comprehensive overview of the basic and applied research status of robotics in dentistry and discusses its development and application prospects in several major professional fields of dentistry. Methods: A literature search was conducted on databases: MEDLINE, IEEE and Cochrane Library, using MeSH terms: [“robotics” and “dentistry”]. Result: Forty-nine articles were eventually selected according to certain inclusion criteria. There were 12 studies on prosthodontics, reaching 24%; 11 studies were on dental implantology, accounting for 23%. Scholars from China published the most articles, followed by Japan and the United States. The number of articles published between 2011 and 2015 was the largest. Conclusions: With the advancement of science and technology, the applications of robots in dental medicine has promoted the development of intelligent, precise, and minimally invasive dental treatments. Currently, robots are used in basic and applied research in various specialized fields of dentistry. Automatic tooth-crown-preparation robots, tooth-arrangement robots, drilling robots, and orthodontic archwire-bending robots that meet clinical requirements have been developed. We believe that in the near future, robots will change the existing dental treatment model and guide new directions for further development

ニッケルアレルギー惹起相におけるセマフォリン７Aの効果

Background: Metal allergy is caused by many factors, including cells, cytokines, chemokines, or the environment. Recent studies suggested semaphorin7A (Sema7A), expressed on activated T cells, is crucial to produce inflammation through α1β1 integrin on monocytes and macrophages. However, the role of Sema7A on keratinocytes in metal allergy is still unclear. In this study, we focused on keratinocytes since they are known as an important player for skin immunity, and analyzed the effect of Sema7A expressed on keratinocytes in the development of metal allergy. Materials and Methods: Mouse keratinocyte line PAM2.12 cells were treated with NiCl2 to analyze the expression of Sema7A. Ni allergy was induced in female C57BL/6J mice (6-8 weeks old) with or without Sema7A suppression to confirm if Sema7A is necessary to produce allergic reactions to NiCl2. Results: NiCl2 enhanced the expression of Sema7A in a dose and time-dependent manner after 72 hours of stimulation. PAM 2.12 produced TNF-α in response to NiCl2, and this secretion was reduced by Sema7A inhibition. In a mouse model, ear thickness, at 48 hours after NiCl2 injection, was significantly decreased by Sema7A siRNA administration. Conclusions: Sema7A is essential to produce an allergic reaction to NiCl2, especially during the effector phase. Since the interaction between Sema7A and α1β1 integrin enhances inflammation in many skin diseases, this interaction may also have possibilities to be a therapeutic target for metal allergy

Semaphorin 3A : A potential target for prevention and treatment of nickel allergy

Metal allergy is one of the typical immune disorders encountered during the application of dental/medical materials and has a highly complex pathogenic mechanism. Semaphorin 3A (Sema3A), a member of the semaphorin family, is reported to be involved in various immune disorders. However, its role in metal allergy has not been clarified yet. Herein, we show that Sema3A expression was upregulated in nickel (Ni) allergy-induced mouse ear tissue and in NiCl2-stimulated mouse keratinocytes. Moreover, Sema3A regulated tumor necrosis factor-alpha production and mitogen-activated protein kinase activation in keratinocytes. The specific deletion of Sema3A in keratinocytes did not affect immune cell infiltration but reduced edema and ear swelling; it also impeded Th1 responses to cause a slight alleviation in Ni allergy in mice. Our results demonstrate that Sema3A promotes the development of metal allergy and should be explored as a potential target for the prevention and treatment of metal allergy

Novel Magnetic Attachment System Manufactured Using High-Frequency Heat Treatment and Stamp Technique : Introduction and Basic Performance

Recently, a novel magnetic attachment with extremely low cost and high performance was developed. This article aims to introduce a novel magnetic attachment and to evaluate its basic eligibility for denture retention in clinical practice. The novel magnetic attachment system used in this study was the direct-bonding root-keeper-type Magteeth™ MT800 (MagneDesign, Nagoya, Japan). The retentive force without displacement (position 0) and after horizontal displacement to positions 0.5, 1, 1.5, 2, 2.5, and 3 mm were measured. The values relative to the retentive force without displacement were gradually decreased to 82.7 ± 16.3%, 68.8 ± 17.1%, 62.4 ± 15%, 47.2 ± 13.1%, 35.7 ± 9.9%, and 20.7 ± 6.5%, respectively. The retentive force and magnetic field strength did not change significantly after the load test (100 N load, 10,000 times). No new gap between the metal and resin was found in the root keeper- and magnet assembly-embedded blocks after the load test. Some scratches on magnetic assembly and root keeper surface, while no change in the resin texture after the load test were observed. Based on the findings of this preliminary study, this novel low-cost magnetic attachment exhibited favorable retention, strength, and durability for clinical use

Discovery of Dying Active Galactic Nucleus in Arp 187: Experience of Drastic Luminosity Decline within 10410^4 years

Arp 187 is one of the fading active galactic nuclei (AGN), whose AGN activity is currently decreasing in luminosity. We investigate the observational signatures of AGN in Arp 187, which trace various physical scales from less than 0.1 pc to the nearly 10 kpc, to estimate the longterm luminosity change over $10^{4}$ years. The VLA 5 GHz, 8 GHz, and the ALMA 133 GHz images reveal bimodal jet lobes with $\sim$5 kpc size and the absence of the central radio-core. The 6dF optical spectrum shows that Arp 187 hosts narrow line region with the estimated size of $\sim$1 kpc, and the line strengths give the AGN luminosity of $L_{\rm bol}=1.5 \times 10^{46}$ erg s$^{-1}$. On the other hand, the current AGN activity estimated from the AGN torus emission gives the upper bound of $L_{\rm bol} < 2.2 \times 10^{43}$ erg s$^{-1}$. The absence of the radio-core gives the more strict upper bound of the current AGN luminosity of $L_{\rm bol} < 8.0 \times 10^{40}$ erg s$^{-1}$, suggesting that the central engine is already quenched. These multi-wavelength signatures indicate that Arp 187 hosts a "dying" AGN: the central engine is already dead, but the large scale AGN indicators are still observable as the remnant of the past AGN activity. The central engine has experienced the drastic luminosity decline by a factor of $\sim10^{3-5}$ fainter within $\sim10^{4}$ years, which is roughly consistent with the viscous timescale of the inner part of the accretion disk within $\sim$500 years.Comment: 15 pages, 8 figures, accepted for publication in Ap

Reliability of Screening Methods to Diagnose Oral Dryness and Evaluate Saliva Secretion

In this study, we evaluated the reliability and reproducibility of widely implemented salivary flow rate and oral dryness tests. In experiment 1, twenty young and healthy Japanese participants volunteered to participate. For each participant, the oral moisture (OM) level, unstimulated whole saliva volume (U-WSV), and stimulated whole saliva volume (S-WSV) were measured at the same time on two separate days. In experiment 2, twenty-seven patients who were over 65 years of age volunteered to participate. The OM level and U-WSV were measured at the same time on two separate days. In Experiment 1, the intra-class correlation coefficients (ICCs) corresponding to the S-WSV, U-WSV, and OM level were 0.23, 0.28, and 0.16, respectively, for the young participants. In Experiment 2, the ICCs corresponding to the U-WSV/spitting and OM level were 0.83 and 0.12, respectively, for the older participants. The results of Bland–Altman analysis confirmed the absence of systematic error, with the exception of the OM level results in Experiment 2, which indicated systematic bias. In conclusion, we believe that there is currently no consistent and reliable screening test for assessing salivary flow rate and oral dryness, although the spitting test was determined to be highly reliable

ホテツ ソウチ ニヨル コジン ニンショウ システム ニ カンスル ブンケンテキ コウサツ

In disasters such as hydraulic bore, earthquakes and fire, the oral structure including the dental prostheses can provide identifying information. Over the years, many different personal identification system of dental prostheses have been reported. This present study analyzes the published literature offering the description of the personal identification system of dental prostheses. Two databases, “PubMed” and “Japana Centra Revuo Medicina” were searched to retrieve research papers referred to the personal identification system of dental prostheses. Twenty four papers were selected from the database with the criteria, and they were reviewed. 　This literature search showed that the personal identifications in three kinds of dental prostheses: removable denture, crown and implant were reported; and more papers on removable dentures were extracted compared to the crown and implant, however there is no high quality paper indicating that the structured methods for personal identification of dental prostheses is effective. 　A new method and common write format for personal identification are required to improve the present problems, and our systems using fluorescent material and ultraviolet light and femtosecond pulse laser-oriented recording system would be effective

Magnet-Retained Two-Mini-Implant Overdenture : Clinical and Mechanical Consideration

Two-implant overdentures have become the accepted treatment for restoring mandibular edentulism. The dimensions of regular implants sometimes limit their use, such as in the case of narrow ridges. Mini-implants with reduced diameters (less than 3.0 mm) enable insertion into narrow ridges. A magnet-retained two-mini-implant overdenture system was developed and is described in this paper. Additionally, we describe a clinical mandibular procedure using the system and evaluate its biomechanical performance

NuSTAR Discovery of Dead Quasar Engine in Arp 187

Recent active galactic nucleus (AGN) and quasar surveys have revealed a population showing rapid AGN luminosity variability by a factor of $\sim10$. Here we present the most drastic AGN luminosity decline by a factor of $\gtrsim 10^{3}$ constrained by a NuSTAR X-ray observation of the nearby galaxy Arp 187, which is a promising "dead" quasar whose current activity seems quiet but whose past activity of $L_\mathrm{bol} \sim 10^{46}$ erg s$^{-1}$ is still observable at a large scale by its light echo. The obtained upper bound of the X-ray luminosity is $\log (L_{\rm 2-10 keV}/{\rm erg} {\rm s}^{-1}) < 41.2$, corresponding to $\log (L_\mathrm{bol}/{\rm erg} {\rm s}^{-1}) < 42.5$, indicating an inactive central engine. Even if a putative torus model with $N_\mathrm{H} \sim 1.5 \times 10^{24}$ cm$^{-2}$ is assumed, the strong upper-bound still holds with $\log (L_{\rm 2-10 keV}/{\rm erg} {\rm s}^{-1}) < 41.8$ or $\log (L_\mathrm{bol}/{\rm erg} {\rm s}^{-1}) < 43.1$. Given the expected size of the narrow line region, this luminosity decrease by a factor of $\gtrsim 10^3$ must have occurred within $\lesssim 10^4$ yr. This extremely rapid luminosity/accretion shutdown is puzzling and it requires one burst-like accretion mechanism producing a clear outer boundary for an accretion disk. We raise two possible scenarios realizing such an accretion mechanism: a mass accretion 1) by the tidal disruption of a molecular cloud and/or 2) by the gas depletion as a result of vigorous nuclear starformation after rapid mass inflow to the central engine.Comment: 7 pages, 2 figures, accepted for publication in ApJ