Three-dimensional positions of the center of resistance of the maxillary canine distal movement under orthodontic force loading.

Using finite-element analysis, we aimed to determine the center of resistance (CRes) of the maxillary canine for setting orthodontic forces. The inclination of the canine was measured by first loading from the mesial to the distal side of the mesial root surface, then the position and direction of the load that minimized the inclination were investigated. The CRes was defined as the set of midpoints of the minimum distances between two inclination lines. Twenty-one CRes values were calculated from a set of seven lines. These CRes data were then aggregated as a 95% confidence ellipsoid of width 0.170×0.016×0.009 mm with center points 4.269, 0.224, and 4.315 mm in the apical, mesial, and lingual directions from the origin, respectively. Further studies are required to effectively apply the CRes identified in this study to clinical applications.

Three-dimensional location and distribution of the center of resistance in the maxillary first molar applied to occlusal force.

We aimed to investigate the center of resistance (CRes) of the maxillary first molar to set the occlusal force through finite element analysis. The inclination of the molar was measured, with loading to the root on the crown, and the position and direction of the load that minimized the inclination were investigated. The CRes was defined as the set of midpoints of the minimum distances between the two lines. Nine hundred and ninety CRes points were estimated from forty-five lines. The CRes was estimated as the point 1.22 mm (Z), -0.74 mm (X), and 0.23 mm (Y) from the origin in the apical, distal, and buccal side directions, respectively, with an ellipsoid area of 1.578 (Z) mm×0.097 (X) mm×0.100 (Y) mm. Further research is required to make effective use of the CRes identified in this study for clinical applications.

A pregnant woman with severe dyspnoea.

Preterm delivery is a feasible option in the third trimester of pregnancy in the treatment of pregnant women with acute respiratory distress syndrome due to miliary tuberculosis with respiratory failure https://bit.ly/3stKOzj.

Optimal timing of elective repeat cesarean deliveries of term singleton pregnancies: A multicenter cross-sectional study.

OBJECTIVE: Cesarean deliveries must be optimally timed to minimize their effects on mothers and neonates. This study aimed to determine the optimal timing of elective repeat cesarean deliveries to reduce the incidence of neonatal respiratory disorders and of emergent cesarean deliveries. MATERIALS AND METHODS: This multi-center, cross-sectional, retrospective analysis evaluated data on the maternal and neonatal outcomes of 856 singleton pregnancies scheduled for elective repeat cesarean deliveries at 37-39 weeks' gestation. The emergent cesarean delivery and neonatal respiratory disorder risks were analyzed according to the scheduled cesarean delivery times. RESULTS: The elective cesarean delivery rates were 91.0% during the first and 92.6% during the second half of the 37th week of gestation, 88.7% during the first and 82.9% during the second half of the 38th week of gestation, and 62.5% during the first and 33.3% during the second half of the 39th week of gestation. The neonatal respiratory disorder rates were 21.8% for elective cesarean deliveries during the first half of the 37th week of gestation and approximately 8% for elective cesarean deliveries during the second half of the 37th week until the first half of the 38th week of gestation. No neonatal respiratory disorders occurred among the babies delivered by elective cesarean deliveries during the 39th week of gestation. CONCLUSION: For improved maternal and neonatal outcomes in the Asian population, it may be better to perform scheduled elective repeat cesarean deliveries from the second half of the 37th week of gestation until the 38th week of gestation following confirmation of gestational age by early first trimester ultrasonography.

Pregnancy in hereditary sensory and autonomic neuropathy type V: A case report and literature review.

OBJECTIVE: Hereditary sensory and autonomic neuropathies (HSANs) are a clinical heterogenous group of inherited neuropathies featuring prominent sensory and autonomic involvement. We report on the management of pregnancy and delivery in a woman with HSAN type V (HSAN-V) that is a rare inherited disease characterized by pain insensitivity, and partial anhidrosis. CASE REPORT: A 25-year-old woman with HSAN-V at six weeks of gestation was referred to our hospital. She decided to continue her pregnancy after the genetic counseling. A multidisciplinary team including her decided to undergo cesarean section due to her short stature and the risk of an emergency in normal delivery. She successfully gave birth at 38 weeks of gestation by cesarean section under general anesthesia following an uneventful pregnancy course. CONCLUSION: Cesarean section seems favorable to vaginal delivery in women with HSANs.

Can hypochlorous acid be a powerful sanitizer to replace alcohol for disinfection ? -Its bactericidal, degradation of the solutions under various storage condition, and steel rust effects.

Coronavirus disease pandemic has led to a shortage of disinfectant alcohol (DA; 76.9-81.4% ethanol solution) in Japan. This study investigated the availability of hypochlorous acid (HA) as an alternative disinfectant to DA in clinical environment. HA is a safe and economical disinfectant with a broad antibacterial spectrum and low risk of hand irritation, which is used worldwide. In this study, HA and sodium hypochlorite solution (SH) were degraded over time and the degradation was accelerated by temperature and lighting. Results of bactericidal effects of HA revealed that the realistic effective concentration should be 200 ppm. Compared with DA, the dental carbon steel burs were more severely rusted by SH and HA. These results indicated that high concentration of HA generated on-site could be an effective and safe disinfectant for use immediately after generation with consideration of object materials in clinical environment, as an alternative to DA.

Postpartum unscarred uterine rupture caused by placenta accreta: A case report and literature review.

Our case and the literature review suggest that placenta accreta spectrum, with use of uterotonics and manual removal of placenta, could be risk factors for postpartum unscarred uterine rupture.

Post-contrast Acute Kidney Injury Following Emergency Transcatheter Arterial Embolization for Uncontrollable Postpartum Hemorrhage.

The aim of this study was to investigate the incidence of post-contrast acute kidney injury (PC-AKI) in patients with uncontrollable postpartum hemorrhage undergoing emergency transcatheter arterial embolization (TAE). Data collected included patient characteristics, serum creatinine (SCr) level before and after TAE, iodine quantity of contrast media, time between computed tomography and TAE, diabetes mellitus, hemorrhage volume, and blood transfusion volume. For the diagnosis of PC-AKI, the criteria of the European Society of Urogenital Radiology Guidelines (version 10.0) were used. A total of 71 TAE procedures were performed over a 5-year period, and 47 patients met the inclusion criteria. Preprocedural renal function and change of SCr were positively correlated (P < .001), although no patients met the PC-AKI criteria and none showed renal impairment on the follow-up examination (95% upper confidence limit = 6.2%). Total iodine quantity was not correlated with SCr change. Postpartum hemorrhage was finally controlled in all 47 patients, and they were subsequently discharged. In conclusion, emergency TAE for patients with uncontrollable postpartum hemorrhage was a safe and effective procedure, not only in terms of bleeding-related and other outcomes but also with respect to the risk of PC-AKI.

Semi-powered exoskeleton that regulates the muscular activity of jaw movement for oral functional rehabilitation/training.

The sequential oral functions of mastication and swallowing are well tuned in humans. To prevent oral hypofunction as a risk factor for systemic frailty by oral motor training, semi-powered exoskeleton was developed and evaluated its loading/assist effects by monitoring electromyography signals and saliva secretion in healthy persons. The actuator of the driving unit combined mechanical and powered mechanics and was driven alternatively by an unpowered stainless-steel spring system for jaw-opening training by loading and a powered shape-memory alloy spring system to assist jaw closing. Sequential device movement was controlled by two electronic circuits with two magnetic switching systems to match human jaw movement. This exoskeleton realized a 25% increase of jaw-opening muscular activity for training, 15% saving of jaw-closing muscular activity for assistance, and 15% enhancement of saliva secretion, which could contribute to the prevention of oral frailty by maintenance and strengthening of oral function in the upcoming super-aging society.

Safety and Efficacy of Aortic Vs Internal Iliac Balloon Occlusion for Cesarean Delivery in Coexisting Placenta Accreta and Placenta Previa.

PURPOSE: To investigate safety and efficacy of intra-aortic balloon occlusion (IABO) versus internal iliac artery balloon occlusion (IIABO) for cesarean delivery in coexisting placenta accreta and placenta previa. MATERIALS AND METHODS: From 2006 to 2019, 60 pregnant women who had undergone preoperative IABO (n = 28) and IIABO (n = 32) for cesarean delivery in coexisting placenta accreta and placenta previa were retrospectively identified, and their medical records and relevant imaging were reviewed. RESULTS: Maternal characteristics (age, gravidity, previous cesarean delivery, gestational age, and neonatal weight) were similar in both groups. Estimated blood loss, volume of blood transfusion, length of hospitalization, and rate of hysterectomy were not significantly different between the groups. Operation time (the duration of cesarean delivery and hysterectomy, p < 0.05), total time of balloon occlusion (p < 0.01), and fetal radiation dose (p < 0.001) in the IABO group were less than in the IIABO group. No severe complications related to the balloon occlusion procedure were noted in either group. CONCLUSION: IABO and IIABO are safe and effective options for cesarean delivery in patients with combined placenta accreta and placenta previa. The average operation time, balloon occlusion time, and fetal radiation dose in patients with IABO are less than in patients with IIABO. There were no complications related to balloon occlusion of the aorta or internal iliac artery.

Low temperature polytetrafluoroethylene (PTFE) coating improves the appearance of orthodontic wires without changing their mechanical properties.

A strong esthetic demand exists for white-colored rather than metallic-colored dental appliances. Polytetrafluoroethylene (PTFE), which is chemically stable with extremely low friction, is a suitable white-colored coating for dental appliances. In the conventional PTFE coating process, base materials are heated to approximately 400°C, which could change their mechanical properties. Examination of the PTFE-coating of stainless steel, nickel titanium (Ni-Ti), and ß-titanium (Ti-Mo and Ti-Nb) revealed that the conventional 380°C coating, but not the newly developed low temperature coating at 200°C, reduced elasticity and bendability, and changed the crystal structure, especially in Ni-Ti and Ti-Nb wires. PTFE-coating at 200°C resulted in less discoloration, microbial adhesion, and friction against brackets, and higher tolerance of wear than did the conventional 380°C coating. These results suggest that low temperature PTFE coating is an excellent method for improving the metallic appearance of orthodontic wires without changing their mechanical properties.

Estimation of three-dimensional long axes of the maxillary and mandibular first molars with regression analysis.

The purpose of this study was to determine the long axes of molars with multiple roots through ordinary least squares regression (LSR) and to compare them with the axes defined by principal component analysis (PCA). Three-dimensional radiological images of 20 dry skulls were obtained by cone-beam computed tomography (CBCT). Data from maxillary and mandibular first molars were extracted from the CBCT DICOM data with a three-dimensional image visualization system. The obtained data were reconstructed, converted to STL files, and three-dimensional coordinate values were extracted. The long axes were estimated by an algorithm to synchronize the LSR line with the horizontal axis which was translated to the vertical axis. The axes of the molars defined by LSR were compared with the axes of the molars defined by PCA. The coordinate point number of each molar was 5400-5800. The algorithm for determining the tooth axes in this study consisted of four stages containing three steps each. The distance between the two axes calculated by the two methods (LSR and PCA) on the horizontal plane through the origin was less than 10-12 mm and the deviations between them were less than 0.003°. The long axes of the molars estimated by LSR agree almost exactly with the axes estimated by PCA, and the accuracy is sufficient for clinical usage; however, the distance between them would shorten with a more severe convergence condition of the α value at each stage of this LSR system.

Effects of magnetic fields from electric toothbrushes on fluoride- and oral bacteria-induced corrosion of orthodontic metallic wires.

Corrosion of metallic materials in the oral cavity could trigger metal allergy in patients. To clarify the risk elevation of magnetic fields (MFs) exposure on metallic corrosion when combined with fluoride-containing dental care products and indigenous oral bacteria, we investigated electric toothbrush-derived MF-induced corrosion of orthodontic stainless steel (SUS) and nickel titanium (Ni-Ti) wires in the presence of fluoride and oral bacteria, i.e. Streptococcus (S) mutans and S. sanguinis. MFs induced an electric current in the wires under both environments. Oral bacteria corroded SUS wires, and fluoride corroded SUS and Ni-Ti wires as previously reported; however, no additive or synergistic effects of MF exposure on fluoride- and microbiologically-induced metallic corrosion were observed. These results suggest that the MFs from electric toothbrushes do not increase the risk of corrosion of metallic appliances, given that the oral environment of patients is exposed to oral bacteria and fluoride-containing products.

Polytetrafluoroethylene (PTFE): A resin material for possible use in dental prostheses and devices.

Polytetrafluoroethylene (PTFE) is chemically stable, non-toxic to humans, highly resistant to heat and chemicals, and has an extremely low coefficient of friction. Therefore, PTFE is used in medical applications. We focused on the physical properties of PTFE in relation to its application as a material for use in prostheses and dental devices/instruments. PTFE exhibited low wear (approximately 1/3 that of bovine tooth, and 1/2 that of type III gold alloy), low dynamic friction (approximately 1/5 that of the other specimens), low hardness (4.8HV1.0), low coloration, and low bacterial adhesion, compared to other specimens except porcelain in wear and coloration test (p<0.01). These results suggest that PTFE could have applications in some prostheses for provisional and/or permanent use, and dental instruments/devices by providing excellent impact absorption, high wear resistance for maintenance of occlusal vertical dimension and original function, and ease of cleaning.

Five-axis laser milling system that realizes more accurate zirconia CAD/CAM crowns by direct milling from fully sintered blocks.

Directly milling zirconia computer-aided design (CAD)/computer-aided manufacturing (CAM) crowns from fully sintered zirconia blocks using a five-axis laser milling system, compared with three-axis milling and full sintering by heating milled semi-sintered crowns, was investigated. The mechanical characteristics of zirconia specimens were similar across groups. The order of the marginal gap was three-axis>conventional (lingual thickness of 1.5 mm>0.5 mm)>five-axis group (close to zero). The marginal shape was almost perfectly circular in all groups. The internal corner shape and gap were almost perfect for the five-axis milled crown but not for conventional and three-axis crowns. The roundness of the marginal and internal shapes was almost perfect in the five-axis milling group but not for the three-axis and conventional groups. These small distortions result in large marginal gaps. Results of the present study suggest the superiority of the five-axis milling system in creating a zirconia prosthesis.

Prevalence of rear seat belt use among pregnant women in a suburban area of Japan.

AIM: The aim of this study was to clarify the prevalence and influencing factors of rear seat belt use among pregnant women. METHODS: Questionnaires were given to 1546 pregnant women who visited obstetrics clinics and hospitals for prenatal checkups from October to December 2013. A total of 1494 pregnant women (96.6%) agreed to participate in this study and completed the questionnaire. RESULTS: Fewer than 20% of the rear-seat passengers 'always' used seat belts before and during pregnancy, whereas a third 'never' used a seat belt before or during pregnancy. There was no significant decrease in seat belt use by rear-seat passengers during compared to before pregnancy. Multivariate analysis revealed that age, knowledge of how to use a seat belt during pregnancy, belief in the compulsory use of a rear seat belt and driver behavioral characteristics before pregnancy were associated with rear seat belt use during pregnancy. CONCLUSIONS: The prevalence of fastening seat belts was substantially low. The provision of information regarding proper seat belt use and its role in protecting the fetus may increase use.

Perinatal mortality in Japanese women diagnosed with gestational diabetes mellitus and diabetes mellitus.

AIMS: The objective of this study was to determine how many pregnant Japanese women with diabetes mellitus (DM)/gestational diabetes mellitus (GDM) experience perinatal mortality in the presence of fetal anomalies. METHODS: Our investigation included data from 205 secondary/tertiary obstetric facilities located widely in Japan. The Japan Ministry of Health, Labour and Welfare Vital Statistics of Japan was used for comparison. RESULTS: Of 237 941 women giving birth at 205 hospitals, 1796 (0.8%) and 13 037 (5.5%) had DM and GDM, respectively. The perinatal mortality rates (per 1000 births) were 10.6 (19/1796) for women with DM, 5.2 (68/13037) for women with GDM, and 3.7 (7612/2039504) for the general Japanese population. Detailed information was available for 63 (72%) of the 87 perinatal deaths occurring in women with diabetes including DM and GDM; fetal anomalies were associated with 40% (25/63) of perinatal deaths, exceeding 16% (1211/7612) in the general Japanese population (P < 0.0001). The leading four fetal anomalies associated with perinatal mortality in women with diabetes were fetal trisomy (6 cases: 1 of trisomy-13 and 5 of trisomy-18), non-immune hydrops fetalis (5 cases), cardiac deformities (3 cases) and holoprosencephaly (2 cases). CONCLUSIONS: Perinatal mortality was more likely to occur in women with glucose intolerance. In the Japanese infants that succumbed to perinatal mortality, fetal anomaly was more prevalent in those born to women with a glucose intolerance than in those born to the general population.

Intraoral electric potential via oral bacterial power generation -A novel mechanism of biofilm formation.

In the early stages of biofilm accumulation, the electric charge of the dental enamel and pellicle surfaces is known to be involved. We therefore investigated the relationship between oral hygiene and intraoral electric potential (IoP) in 45 male participants using a double-blind study. IoP, but not body surface electric potential, was loosely correlated with oral hygiene condition (Oral Hygiene Index; OHI). IoP was also loosely correlated with smartphone use; however, there was no significant correlation between smartphone use and OHI. IoP elevation might be caused by OHI elevation resulting from biofilm formation as an internal factor, with smartphone use as an external factor. This in vitro study revealed the generating capacity of Streptococcus mutans accompanied by biofilm accumulation using a microbial fuel cell. These results suggest that IoP elevation is caused by biofilm accumulation induced by power generation of oral bacteria, resulting in elevation of OHI.

Crown shape of maxillary molars with delayed eruption.

The purpose of this study was to explore the crown shapes of maxillary molars with delayed eruption (DEMo1) at the position distal to the maxillary second premolar. Included teeth erupted later than the average for the maxillary first molar eruption in Japanese females (6.58 ± 0.67 years) by more than two standard deviations. Crown shapes of 12 four-cusped left DEMo1 teeth were compared with those of 25 four-cusped left maxillary first molars (U6n) and 25 four-cusped left maxillary second molars (U7n) from different patients with normal eruption. Seven landmarks were established on the reference plane containing the mesiobuccal, distobuccal and mesiolingual cusp tips of the molars; the origin was defined as the center of gravity of these three points. According to the obtained discriminant function (percentage of correct classifications, 84%), five DEMo1 teeth were classified as U6n and the other seven as U7n. The DEMo1 teeth were also classified into two subgroups, the U6n-close and U7n-close groups, according to the location of the distolingual cusp tip. These results suggest that DEMo1 teeth could include U6 and U7 with delayed eruption or could be an intermediate between U6 and U7, according to their crown shapes.

Formation and development of maxillary first molars with delayed eruption.

Cases of congenitally missing and delayed eruption of the maxillary first molar are rare. However, in recent years, we have experienced cases of suspected delayed eruption of or congenitally missing first molars. The purpose of this study was to analyze the formation of delayed erupted maxillary first molars (M1) (>2 standard deviations), which play important roles in occlusion, and normal eruption of the maxillary first molars (U6). The frequency of M1 among patients born between 1974 and 1994 in one institution with a clear total patient number and personal oral histories was 1.55 % [80 % bilateral eruption in 8 of 806 male patients (0.99 %) and 23 of 1195 female patients (1.92 %)]. To evaluate the formation and eruption of M1 according to Moorrees's tooth formation stages, panoramic X-ray films were obtained every year for 73 patients with M1 from 3 institutions (20 male and 53 female patients, total 131 M1s) without systematic histories or genetic disorders. The development/growth curve of M1 was fitted to both the logistic curve and U6 curve. The M1 development/growth curve was started behind with U6 curve; however, the straight part of the M1 curve exhibited steep inclination compared with the straight part of the U6 curve. The curve of the eruption pathway of M1 also exhibited a sigmoid S shape. These results indicate that the development and migration speed of M1 are faster than that of U6, excluding the delayed start point. These results may help orthodontists in treatment planning for patients with M1.