Accuracy of Orthodontic Anchor Screw Placement Using a 3D-Printed Surgical Guide.

Background Although radiographs and computed tomography (CT) images are reviewed before temporary anchorage device (TAD) implantation, implantation of TADs exactly as planned is difficult. This study aimed to evaluate the accuracy of TAD implantation using an original surgical guide fabricated using cone-beam CT data and computer-aided design software. Methodology The study participants included six experienced orthodontists who had implanted ≥20 TADs, and six inexperienced orthodontists who had never implanted a TAD. Maxillary dental typodont models with radiopaque tooth crowns and roots were used. A total of four TADs were implanted on the buccal sides: between the second bicuspid and first molars and between the first and second molars bilaterally. The accuracy of TAD implantation was examined in two groups: in 12 dental typodont models, TAD implantation was performed using a surgical guide (guide group), and in 12 dental typodont models, TAD implantation was performed without a surgical guide (freehand group). All dental typodont models implanted a total of 96 TADs. The TAD position was evaluated using the CT coordinate system and 3D image measurement software. Using the long axis of the TAD as a reference, the distance between the coronal and apical ends of the implanted TAD and those of the planned TAD, i.e., the ideal implantation position, was measured in both groups along the x, y, and z axes. The medians of the values were compared between the groups. Additionally, the presence of root contact was compared between the experienced and inexperienced orthodontists. Results On the x-axis, the linear deviations (median) of the coronal and apical ends of the TAD in the freehand group were 1.06 mm and 1.36 mm, respectively. In contrast, in the guide group, the deviations were 0.65 mm and 0.90 mm, respectively, and the difference was statistically significant (p = 0.002 and p = 0.005, respectively). On the y-axis, the deviations in the freehand group were 1.13 mm and 1.08 mm, respectively. In contrast, the deviations in the guide group were 0.71 mm and 0.79 mm, respectively, and only the coronal deviations were significantly different between the groups (p = 0.006). On the z-axis, the deviations in the freehand group were 1.44 mm and 1.86 mm, respectively. In contrast, the deviations in the guide group were 0.75 mm and 1.16 mm, respectively, and the difference was statistically significant (p = 0.006 and p = 0.002, respectively). Conclusions The use of a surgical guide allowed for more accurate TAD implantation. Additionally, TAD implantation using a guide prevented root damage.

Identification of Candidate Genes of Familial Multiple Idiopathic Cervical Root Resorption.

INTRODUCTION: Multiple idiopathic cervical root resorption (MICRR) is a disease with an unknown etiology that causes invasive cervical root resorption in multiple teeth. Although previous MICRR genomic studies have identified candidate gene variants, the etiology of the condition remains poorly understood. In the present study, we investigated the genetic causality of MICRR to explore candidate variants. METHODS: Saliva samples from a family containing 2 affected and two unaffected subjects with the dominant transmission of MICRR were subjected to whole-exome sequencing. RESULTS: As a result, we identified novel candidate variants of 10 genes. Each variant was confirmed by Sanger sequencing. Among them, the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP) guidelines classified doublecortin domain containing 1 (c.1099 C > T) and ß-defensin 114 (c.189 T > G) as "pathogenic," and solute carrier family 45 member 2 (c.152_153del) as "likely pathogenic." CONCLUSIONS: These results provide new insight to help clarify the pathogenesis of MICRR, and the variants could be applied for further investigation to understand invasive cervical root resorption.

Development of flapping wing robot and vision-based obstacle avoidance strategy.

Due to the flight characteristics such as small size, low noise, and high efficiency, studies on flapping wing robots are being actively conducted. In particular, the flapping wing robot is in the spotlight in the field of search and reconnaissance. Most of the research focuses on the development of flapping wing robots rather than autonomous flight. However, because of the unique characteristics of flapping wings, it is essential to consider the development of flapping wing robots and autonomous flight simultaneously. In this article, we describe the development of the flapping wing robot and computationally efficient vision-based obstacle avoidance algorithm suitable for the lightweight robot. We developed a 27 cm and 45 g flapping wing robot named CNUX Mini that features an X-type wing and tailed configuration to attenuate oscillation caused by flapping motion. The flight experiment showed that the robot is capable of stable flight for 1.5 min and changing its direction with a small turn radius in a slow forward flight condition. For the obstacle detection algorithm, the appearance variation cue is used with the optical flow-based algorithm to cope robustly with the motion-blurred and feature-less images obtained during flight. If the obstacle is detected during straight flight, the avoidance maneuver is conducted for a certain period, depending on the state machine logic. The proposed obstacle avoidance algorithm was validated in ground tests using a testbed. The experiment shows that the CNUX Mini performs a suitable evasive maneuver with 90.2% success rate in 50 incoming obstacle situations.

When Is the Negative Effect of Abusive Supervision on Task Performance Mitigated? An Empirical Study of Public Service Officers in Korea.

Supervisory leadership has occupied an important place in management literature in identifying the supervisory behaviors that are associated with positive outcomes. However, researchers also have turned their attention to the dark side of supervisory behavior, such as abusive supervision. This study investigates the role of coworker support and self-efficacy in the relationship between abusive supervision and the subordinate's task performance. Data are collected from 192 supervisor-subordinate pairs in the South Korean Army. As hypothesized, when subordinates receive higher levels of coworker support or have higher self-efficacy, abusive supervision is less negatively related to task performance. The implications of the study and directions for future research are discussed.

Effect of ionizing radiation at low dose on transgenerational carcinogenesis by epigenetic regulation.

The objective of this study was to determine the effect of ionizing radiation (IR) exposure of parents on carcinogenesis of the next generation focusing on the epigenetic perspective to clarify the relationship between radiation dose and carcinogenesis in F1 generation SD rats. F1 generations from pregnant rats (F0) who were exposed to gamma rays were divided into three groups according to the dose of radiation: 10 rad, 30 rad, and untreated. They were intraperitoneally injected with 50 mg/kg of diethylnitrosamine (DEN). Carcinogenesis was analyzed by examining expression levels of tumor suppressor genes (TSG) and other related genes by methylation-specific polymerase chain reaction (MSP). DNA methylation in liver tissues was evaluated to discern epigenetic regulation of transgenerational carcinogenesis vulnerability following IR exposure. Numerous studies have proved that transcriptional inactivation due to hypermethylation of TSG preceded carcinogenesis. Results of this study revealed hypermethylation of tumor suppressor gene SOCS1 in group treated with 30 rad. In addition, genes related to DNA damage response pathway (GSTP1, ATM, DGKA, PARP1, and SIRT6) were epigenetically inactivated in all DEN treated groups. In the case of proto-oncogene c-Myc, DNA hypermethylation was identified in the group with low dose of IR (10 rad). Results of this study indicated that each TSG had different radiation threshold level (dose-independent way) and DEN treatment could affect DNA methylation profile irrelevant of ionizing radiation dose.