Assessment of Outcomes From 1-Year Surveillance After Detection of Early Gastric Cancer Among Patients at High Risk in Japan

[Importance] Single endoscopic examination often misses early gastric cancer (GC), even when both high-definition white light imaging and narrow-band imaging are used. It is unknown whether new GC can be detected approximately 1 year after intensive index endoscopic examination. [Objective] To examine whether new GC can be detected approximately 1 year after intensive index endoscopic examination using both white light and narrow-band imaging. [Design, Setting, and Participants] This case-control study was a preplanned secondary analysis of a randomized clinical trial involving 4523 patients with a high risk of GC who were enrolled between October 1, 2014, and September 22, 2017. Data were analyzed from December 26, 2019, to April 21, 2021. Participants in the clinical trial received index endoscopy to detect early GC via 2 examinations of the entire stomach using white light and narrow-band imaging. The duration of follow-up was 15 months. The secondary analysis included 107 patients with newly detected GC (case group) and 107 matched patients without newly detected GC (control group) within 15 months after index endoscopy. [Interventions] Surveillance endoscopy was scheduled between 9 and 15 months after index endoscopy. If new lesions suspected of being early GC were detected during surveillance endoscopy, biopsies were obtained to confirm the presence of cancer. [Main Outcomes and Measures] The primary end point was the rate of new GC detected within 15 months after index endoscopy. The main secondary end point was identification of risk factors associated with new GC detected within 15 months after index endoscopy. [Results] Among 4523 patients (mean [SD] age, 70.6 [7.5] years; 3527 men [78.0%]; all of Japanese ethnicity) enrolled in the clinical trial, 4472 received index endoscopy; the rate of early GC detected on index endoscopy was 3.0% (133 patients). Surveillance endoscopy was performed in 4146 of 4472 patients (92.7%) who received an index endoscopy; the rate of new GC detected within 15 months after index endoscopy was 2.6% (107 patients). Among 133 patients for whom early GC was detected during index endoscopy, 110 patients (82.7%) received surveillance endoscopy within 15 months after index endoscopy; the rate of newly detected GC was 10.9% (12 patients). For the secondary analysis of risk factors associated with newly detected GC, characteristics were well balanced between the 107 patients included in the case group vs the 107 patients included in the matched control group (mean [SD] age, 71.7 [7.2] years vs 71.8 [7.0] years; 94 men [87.9%] in each group; 82 patients [76.6%] vs 87 patients [81.3%] with a history of gastric neoplasm). Multivariate analysis revealed that the presence of open-type atrophic gastritis (odds ratio, 6.00; 95% CI, 2.25-16.01; P < .001) and early GC detection by index endoscopy (odds ratio, 4.67; 95% CI, 1.08-20.21; P = .04) were independent risk factors associated with new GC detection. [Conclusions and Relevance] In this study, the rate of new GC detected by surveillance endoscopy approximately 1 year after index endoscopy was similar to that of early GC detected by index endoscopy. These findings suggest that 1-year surveillance is warranted for patients at high risk of GC

Construction method of a tooth crown model using data generated by micro-focus CT ― Voxel models of anterior and premolar teeth ―

Currently, a number of dental CAD/CAM systems are in operation in Japan. Many of them adopt a non-contact optical system using a CCD camera and light patterns to measure the model teeth. One disadvantage of this method is that it is difficult to measure the parts in the shade. However, this problem can be solved if we can carry out measurements using 3D CT. In this study we have examined how to construct a 3D model of a tooth crown shape using micro-CT data. An R_mCT2 micro-CT manufactured by Rigaku Corporation was used under maging conditions of FOV10（φ10 mm×H10 mm）, 90 kV tube voltage and 160 μA tube current. Basic study models manufactured by KaVo Dental GmbH were used in the imaging, which was carried out in two phases, as the size of the artificial teeth was greater than that of the FOV. The image data was output in 512 slices in the form of DICOM files, and transferred to a personal computer. We examined the CT values of all the voxels of all images using software we developed ourselves. Based on the results, we determined the threshold by comparing the distribution of the CT values of the artificial teeth area with those of the remaining area in each image, and extracted the shape of the artificial tooth by binarizing the image. The separate image data was aligned by detecting the location of the closest number of pixels to the binarized image. Artifacts included in the images were removed manually and the completed voxel data output in DICOM format. Shape was confirmed using free DICOM viewer software（OsiriX）. As a result, the margin of error for superimposing the contour shape of the split image data is approximately one voxel（± 20 μm）. Artifacts were seen in 20 to 50 slices of the binarized images but because they were minor, we were able to process the images quickly and easily. In this study we were able to construct a high-resolution model of artificial teeth with relative ease. In future, if we can success in realizing low-cost, higher performance dental cone-beam CT, we will be able to use it to measure abutment teeth

A Paced Auditory Serial Addition Task evokes stress and differential effects on masseter-muscle activity and haemodynamics.

This study aimed to determine autonomic and jaw-muscle activities, and haemodynamic responses, to acute experimental mental stress in humans. Eleven healthy men (25.2 ± 3.0 years of age) and five healthy women (23.0 ± 3.7 years of age) performed a standardized mental stress task, the Paced Auditory Serial Addition Task (PASAT). Autonomic function, such as heart rate variability (HRV), and haemodynamic changes were recorded simultaneously. The success rate of the PASAT decreased with increased pace and duration. Low-frequency (5.8 ± 1.1 ms(2)) and high-frequency (5.3 ± 0.6 ms(2)) components of HRV decreased during the PASAT (to 5.0 ± 0.9 ms(2) and 4.6 ± 1.1 ms(2), respectively) as an indication of acute stress. Oxygenated haemoglobin in the masseter muscle (14.6 ± 2.2 10(4) units mm(-3)) remained at an elevated level during the PASAT (15.5 ± 2.5 10(4) units mm(-3)), whereas deoxygenated haemoglobin (7.8 ± 2.3 10(4) units mm(-3)) showed a consistent decrease (to 6.8 ± 2.1 10(4) units mm(-3)). Total haemoglobin and jaw-muscle electromyographic (EMG) activity did not change during the PASAT. Thus, PASAT-induced mental stress changed the parasympathetic/sympathetic balance of the heart and had an acute influence on jaw-muscle haemodynamics, but not on jaw-muscle EMG activity. This non-invasive experimental set-up can be applied to study the effects of repeated or longer-lasting mental stress in order to further the understanding of pathophysiological mechanisms in craniofacial pain conditions

Choice of biomaterials : Do soft occlusal splints influence jaw-muscle activity during sleep? A preliminary report

Aim: The choice of biomaterials for occlusal splints may significantly influence biological outcome. In dentistry, hard acrylic occlusal splints (OS) have been shown to have a temporary and inhibitory effect on jaw-muscle activity, such as tooth clenching and grinding during sleep, i.e., sleep bruxism (SB). Traditionally, this inhibitory effect has been explained by changes in the intraoral condition rather than the specific effects of changes in-occlusion. The aim of this preliminary study was to investigate the effect of another type of occlusal surface, such as a soft-material OS in addition to a hard-type OS in terms of changes in jaw-muscle activity during sleep. Materials and Methods: Seven healthy subjects (mean ± SD, six men and one woman: 28.9 ± 2.7 year old), participated in this study. A soft-material OS (ethylene vinyl acetate copolymer) was fabricated for each subject and the subjects used the OS for five continuous nights. The EMG activity during sleep was compared to baseline (no OS). Furthermore, the EMG activity during the use of a hard-type OS (Michigan-type OS, acrylic resin), and hard-type OS combined with contingent electrical stimulation (CES) was compared to baseline values. Each session was separated by at least two weeks (washout). Jaw-muscle activity during sleep was recorded with single-channel ambulatory devices (GrindCare, MedoTech, Herlev, Denmark) in all sessions for five nights. Results: Jaw-muscle activity during sleep was 46.6 ± 29.8 EMG events / hour at baseline and significantly decreased during the hard-type OS (17.4 ± 10.5, P = 0.007) and the hard-type OS + CES (10.8 ± 7.1, P = 0.002), but not soft-material OS (36.3 ± 24.5, P = 0.055). Interestingly, the soft-material OS (coefficient of variance = 98.6 ± 35.3%) was associated with greater night-to-night variations than baseline (39.0 ± 11.8%) and the hard-type OS + CES (53.3 ± 13.7%, P < 0.013). Conclusion: The present pilot study in small sample showed that a soft-material occlusal splint does not seem to inhibit jaw-muscle activity during sleep. Within the limitation of the study, it appears that the choice of biomaterials for occlusal splints may have a significant impact on the neurobiological regulation of jaw-muscle activity during sleep

Haemodynamic reactions in human masseter muscle during different types of contractions

Objectives : To investigate to what extent different types of jaw-muscle contractions cause haemodynamic reactions in human masseter muscle. Materials and Methods : Eleven healthy volunteers (seven males : 25.0±2.9 years and four females: 23.3±4.3 years) performed three standardized oral-motor tasks : maximal voluntary contractions (MVC ; duration 5 sec, 3 times repetition), tooth grinding (repetitive left and right side grinding from intercuspal position to canine-to-canine position at 0.5 Hz keeping 50% MVC for a total of 10 times), and 1-min left-side gum chewing at 1 Hz. Haemodynamic characteristics were measured in the left masseter muscle with the use of a laser blood oxygenation monitor (BOML1TRW, OMEGAWAVE INC., Tokyo, Japan). Electromyographic (EMG) activity from right and left masseter muscle was simultaneously monitored (500 Hz sample frequency) during the tasks. 1-ANOVA followed by Dunnett’s test was used. Results : Oxygenated haemoglobin (OXYHb : 13.5±0.2 104 units/mm3) and deoxygenated haemoglobin (deOXYHb : 7.6 ± 0.3 104 units/mm3) did not change significantly during the MVC task (13.9±0.2 and 7.8±0.3 104 units/mm3, respectively, P>0.065), however, the total haemoglobin (TOTALHb : 22.1±0.3 104 units/mm3) showed a significant increase (22.7±0.3 104 units/mm3, P=0.003) during the MVC. Tissue blood oxygen saturation was not changed during the MVC (P=0.164). During the tooth grinding task, OXYHb, deOXYHb, TOTALHb, and tissue blood oxygen saturation (StO2) remained constant (P>0.127). Finally, the chewing task was associated with significant decreases in StO2 (67.9±0.7%, P=0.006) related to a decrease in OXYHb (14.0±0.2 104 units/mm3, P=0.040) compared to baseline (68.8±0.7% and 14.2 ±0.3 104 units/mm3, respectively). Conclusion : These results showed that high-intensity experimental tooth clenching caused constriction-like reactions in the masseter muscle whereas tooth grinding did not cause detectable changes in haemodynamic characteristics of masseter muscle. Finally, the findings indicated that rhythmic dynamic contractions might lead to oxygen deficit in the masseter muscle. The present data may have implications for understanding the potential pathophysiological consequences of different types of oral-motor tasks, e.g., bruxism and prolonged mastication

Site-to-site variation of muscle activity and sensitivity in the human anterior temporalis muscle: Implications for contingent stimulation

Objective: To evaluate variation of electromyographic (EMG) activity and sensitivity between different sites of anterior temporalis (AT) muscle. Materials and methods: Sixteen healthy subjects (eight men: 28.8 ± 5.2 year old and eight women: 29.1 ± 3.9) participated in one experimental session. EMG activity during masticatory muscle contraction was recorded from nine sites at the AT muscle in a 3 x 3 grid with 1 cm between. The subjects maintained steady 30% of maximal voluntary contraction (MVC) using visual feedback. The surface EMG electrode was moved sequentially between these nine test sites and the contractions were repeated. One site was tested four times to assess test-retest variability. The sensory threshold to electrical stimulation and impedance was also measured at the same sites as the placement of EMG electrodes. Results: The 30% MVC force values did not differ between sites (p = 0.863) or within the same site (p = 0.995) due to the feedback. The EMG activity during 30% MVC was highest at the anterior-superior site (p < 0.05) with a marginal difference within the same site (p = 0.044). Impedance was higher at the posterior-superior, posterior-middle, and posterior-inferior sites (p < 0.05). The sensory threshold was highest at the posterior-superior site (p < 0.05). Conclusions: These findings showed that electrodes close to the hairline have higher impedance and sensory thresholds and should be avoided. The anterior-superior site produces the highest EMG activity and lower sensory thresholds and can be recommended as the optimal site to place the electrode for contingent stimulation

Does restriction of mandibular movements during sleep influence jaw-muscle activity?

AIM: To investigate the effect of restriction of mandibular movements during sleep on jaw-muscle activity. MATERIALS AND METHODS: Eleven healthy subjects (four men, seven women; mean age 25.9 ± 3.1 years) with self-reports and clinical indications of sleep-bruxism participated in three randomized sessions with three different types of oral appliances: 1) a full-arch maxillary and mandibular appliances which did not allow any mandibular movement, i.e., restrictive oral appliance (ROA), 2) full-arch maxillary and mandibular oral appliances (MMOA) with no restrictions of mandibular movements, and 3) a conventional full-arch flat stabilization appliance, i.e., maxillary oral appliance (MOA). Baseline recordings of jaw-muscle activity during sleep without any oral appliance were performed and followed by one week of nightly use of the oral appliances. After the baseline recording, subjects did three sessions with oral appliance during sleep. During the last night in each session, jaw-muscle activity was recorded and compared to baseline values. A detection threshold of 10 % of maximal voluntary clenching was used to analyze the electromyographic (EMG) activity from both sides of the masseter muscles and in accordance with published criteria (Lavigne et al. 1996). RESULTS: All subjects completed the experimental protocol. Regarding to the average of left and right sides, jaw-muscle activity expressed as number of EMG episodes per hour sleep was significantly lower during MOA (5.2 ± 1.1 episodes/h) compared to baseline values (6.7 ± 1.2, P < 0.01). Furthermore, the number of EMG bursts per hour sleep was significantly lower for ROA (28.3 ± 5.0 bursts/h) and MOA (25.0 ± 6.8) compared to baseline values (40.9 ± 7.7, P < 0.05). The number of phasic EMG episodes and bursts (ROA: 1.5 ± 0.4 episodes/h and 14.8 ± 2.8 bursts/h, MMOA: 1.9 ± 0.3 and 17.7 ± 4.0, MOA: 1.5 ± 0.5 and 15.1 ± 4.7) especially decreased for all three types of appliances compared to baseline (3.0± 0.5 and 29.2 ± 5.8, P < 0.05). CONCLUSION: The results indicated that restriction of mandibular movements with oral appliances may not have major influence on jaw-muscle activity during sleep but rather that the immediate effect of any combination of oral appliances lead to a suppression of EMG bursts per hour of sleep