Using digital image correlation to measure displacement and strain during involving distal movement of anterior teeth with clear aligner.

To investigate methods to suppress the bowing effects of lingual inclination and anterior tooth extrusion, digital image correlation (DIC) was used to evaluate aligner displacement in three-dimensions through comparing the distal movement of six and four anterior teeth. Computed tomography scans were used to measure aligner thickness and shape. Based on displacement direction and magnitude, a desirable deformation mode with minimal lingual inclination and extrusion was observed during distal movement of four anterior teeth. The aligner had a rigid "constriction zone" between the lateral incisor and the canine, facilitating control localized to the anterior teeth and minimizing the reaction of the molars. The mechanical behavior of aligners was greatly affected by the method of anterior teeth movement and the shape of aligners. DIC-based displacement measurements are useful in investigating correction directionality.

Particle Size Analysis in Aerosol-Generating Dental Procedures Using Laser Diffraction Technique.

The global outbreak of coronavirus disease 2019 (COVID-19) has raised concerns about the risk of airborne infection during dental treatment. Aerosol-generating dental procedures (AGDP) produce droplets and aerosols, but the details of the risks of COVID-19 transmission in AGDP are not well-understood. By discriminating between droplets and aerosols, we devised a method to measure particle size using laser diffraction analysis and evaluated aerosols generated from dental devices for providing a basis for proper infection control procedures. The droplets and aerosols generated from dental devices were characterized by multimodal properties and a wide range of droplet sizes, with the majority of droplets larger than 50 µm. AGDP emitted few aerosols smaller than 5 µm, which are of concern for pulmonary infections due to airborne transmission. In addition, the use of extraoral suction was found to prevent the spread of aerosols from high-speed dental engines. This study suggests that the risk of aerosol infections is considerably limited in regular dental practice and that current standard precautions, such as mainly focusing on protection against droplet and contact infections, are sufficient. While several cases of airborne transmission of COVID-19 in general clinics and emergency hospitals have been reported, cluster outbreaks in dental clinics have not yet been reported, which may indicate that AGDP does not pose a significant threat in contributing to the spread of SARS-CoV-2.

Methods in Genetic Analysis for Evaluation Mandibular Shape and Size Variations in Human Mandible.

ABSTRACT: The human mandible has been investigated from both clinical and evolutionary perspectives. Recent advances in genome science have identified the genetic regulation of human mandibular shape and size. Identification of genes that regulate mandibular shape and size would not only enhance our understanding of the mechanisms of mandibular growth and development but also help define a strategy to prevent mandibular dysplasia. This review provides a comprehensive summary of why and how the mandible was evaluated in the human mandible genome study. The variation in human mandibular shape and size has been progressively clarified, not only by focusing on the mandible alone but also by using extremely diverse approaches. The methods of data acquisition for evaluating human mandibular shape and size variation are well established. Furthermore, this review explains how to proceed with future research.

Retrieval of Retained Capsule Endoscopy at Small Bowel Stricture by Double-Balloon Endoscopy Significantly Decreases Surgical Treatment.

GOALS: The aim is to elucidate the efficacy and safety of double-balloon endoscopy (DBE) for small bowel capsule endoscopy (SBCE) retrieval from small bowel stricture and to follow the outcome of the stricture where the SBCE was entrapped. BACKGROUND: The retention of SBCE is a serious adverse event and most retained capsules are retrieved by surgery. There is still no report analyzing the follow-up of patients with stricture after retrieval of entrapped SBCEs by DBE. METHODS: This study was designed a retrospective cohort study. Subjects were 12 consecutive patients with small bowel stricture where retrieval of entrapped SBCE was attempted using DBE. Success rate of the SBCE retrieval by DBE, surgical rate of the small bowel stricture, adverse events of DBE, and outcomes in the follow-up period were evaluated. RESULTS: Diagnoses were Crohn's disease, nonsteroidal anti-inflammatory drugs-induced enteropathy, ischemic enteritis, and carcinoma in 8, 2, 1, and 1 patients, respectively. SBCE was successfully retrieved in 11 of the 12 patients (92%). No adverse events were encountered in all endoscopic procedures such as retrieval of SBCEs and dilation of the strictures. Nine of the 12 patients (75%) did not undergo surgical treatment for the stricture where SBCE was entrapped through the follow-up period (mean, 1675±847 d). CONCLUSIONS: Retrieval of SBCEs using DBE was safe, had a high success rate, and was useful to evaluate the need for surgery. Seventy-five percent of patients with small bowel stricture where the SBCE was entrapped did not require surgery through approximately 5 years.

Effectiveness of piezoelectric surgery in reducing surgical complications after bilateral sagittal split osteotomy.

Our aim was to investigate the effectiveness of piezoelectric surgery, where the osteotomy is made using ultrasonic vibration, in reducing surgical complications after bilateral sagittal split osteotomy (BSSO). Fifty-nine patients with skeletal mandibular prognathism who had mandibular setback with BSSO between January 2009 and April 2011 were included in the study. Piezosurgery was used in 29 cases, and the bone was split using a separator. In the remaining 30 cases, a Lindeman bur was used for the osteotomy and a chisel was used to split the bone. The amount of intraoperative bleeding and the Semmes Weinstein test scores were used as objective variables to evaluate the degree of neurosensory disturbance, and sex, age, use of piezosurgery, degree of setback, operating time, and method of fixation were used as explanatory variables. We used analysis of covariance (ANCOVA) to assess the significance of differences. Intraoperative bleeding was significantly less with age (p=0.003), and longer when operating time was prolonged (p=0.017), and was not influenced by the use of piezosurgery. The Semmes Weinstein test score significantly increased with age (p=0.01), and was significantly greater when piezoelectric surgery was used (p=0.008), and at 3 months, there were signs of more neurosensory disturbance in older patients and those who had had piezoelectric surgery. In this retrospective non-random study piezoelectric surgery reduced neither blood loss nor the incidence of neurosensory disturbance in BSSO.

Small intestinal edema had the strongest correlation with portal venous pressure amongst capsule endoscopy findings.

BACKGROUND/AIM: Previous studies have reported small intestinal lesions in patients with portal hypertensive disease. However, the etiology of these lesions is not clear, as portal venous pressure was not measured in any of these studies. The aim of this study is to clarify the association between small intestinal lesions and hepatic venous pressure gradient (HVPG), which correlates well with portal venous pressure. METHODS: Thirty-five patients with liver cirrhosis were evaluated by capsule endoscopy for small intestinal lesions. HVPG was measured within 3 days of capsule endoscopy. Blood tests, clinical symptoms, Child-Pugh classification and HVPG were analyzed against small intestinal lesions such as edemas, red spots, angiodysplasia and varices. Lesions were categorized according to their location in the duodenum, jejunum or ileum. Edema was evaluated using a 4-grade capsule endoscopy scoring index. RESULTS: HVPG and edema scores increased with Child-Pugh scores. Red spots and angiodysplasia did not correlate with HVPG. Varices were detected in only 5 patients. The edema score was the factor which most strongly correlated with HVPG by multivariate analysis (p = 0.0008). There was also a strong linear relation between edema scores and HVPG (R = 0.75, p < 0.0001). CONCLUSION: Small intestinal edemas showed the strongest correlation with HVPG among all small intestinal lesions.