Effects of microplastics on reproductive characteristics and mechanisms of the marine rotifer Brachionus plicatilis.

Microplastic pollution, especially secondary microplastics (MPs), poses a significant threat to marine ecosystems. Despite its prevalence, the impact of natural-aged MPs on marine organisms, hindered by collection challenges, remains poorly understood. This study focused on 1-3 µm natural-aged MPs collected from Japan's coastal sea, investigating their effects on the rotifer Brachionus plicatilis sensu stricto and its reproductive mechanisms. Rotifers exposed to varying MP concentrations (0, 20, and 200 particles/mL) over 14-day batch cultures exhibited reduced population growth and fertilization rates. Down-regulation of reproductive genes and up-regulation of oxidative stress-related genes were observed, indicating MP-induced disruptions. Enhanced activities of superoxide dismutase and acetylcholinesterase and elevated malondialdehyde levels further emphasized oxidative stress. These findings underscore the detrimental impact of MPs on rotifer reproductivity, shedding light on the underlying mechanisms.

Incidence of Late-Onset Psoriasis Following Tonsillectomy: A Longitudinal Follow-Up Study Using a National Health Screening Cohort.

Tonsillectomy has been suggested as a potential intervention to resolve psoriasis; however, its preventive effects on the development of psoriasis remain unclear. This study aimed to investigate the risk of developing late-onset psoriasis among a Korean adult population who had undergone tonsillectomy. Data from the Korean National Health Insurance Service-Health Screening Cohort between 2002 and 2019 were utilized. Out of a total of 514,866 participants, 1082 participants aged 40 years or older who had undergone tonsillectomy were matched with 4328 control participants using overlap weighting adjustment based on the propensity score. The incidence and hazard ratio (HR) of psoriasis were calculated for both tonsillectomy and control groups. The incidence rates of psoriasis were 1.30% in the tonsillectomy group and 1.20% in the control group. The incidence of psoriasis (overlap-weighted HR = 1.08, 95% confidence of interval = 0.69-1.69, and p = 0.732) did not differ significantly between the patients who underwent tonsillectomy and those in the control group. The cumulative probability of developing psoriasis was not different between the two groups (Log-rank test: p = 0.440). These findings were consistent across subgroups divided by age, sex, income, and region of residence. We found that tonsillectomy did not confer a preventive effect on the development of late-onset psoriasis in the Korean adult population.

Side- and Sinus-Specific Relationships between Chronic Rhinosinusitis and Ischemic Stroke Using Imaging Analyses.

Recent studies have reported chronic rhinosinusitis (CRS) as an independent risk factor for stroke. However, the association with stroke depending on the affected sinuses has not been explored. This study aimed to elucidate the side- and sinus-specific relationship between CRS and ischemic stroke through imaging analyses. We retrospectively reviewed the medical records of patients who were diagnosed with ischemic stroke at a tertiary center. CRS was defined as having a total score of greater than or equal to 4, according to the Lund-Mackay scoring system, through brain magnetic resonance imaging or computed tomography. We investigated the side- and sinus-specific correlation between CRS and ischemic stroke. Subgroup analyses were performed for different age groups. CRS prevalence in patients with ischemic stroke was 18.4%, which was higher than the previously reported prevalence in the general population. Overall, there was no correlation between the directions of the CRS and ischemic stroke (p > 0.05). When each sinus was analyzed, the frontal (Cramer's V = 0.479, p < 0.001), anterior (Cramer's V = 0.396, p < 0.001)/posterior (Cramer's V = 0.300, p = 0.008) ethmoid, and sphenoid (Cramer's V = 0.383, p = 0.005) sinuses showed a statistically significant correlation with the side of stroke, but the maxillary sinus (Cramer's V = 0.138, p = 0.208) did not. In subgroup analyses, a significant right-side correlation between the two diseases was observed in the older-age subgroup (≥65 years old, Cramer's V = 0.142, p = 0.040). Diabetes mellitus (odds ratio = 1.596, 95% confidence interval = 1.204-2.116) was identified as an independent risk factor for having CRS in patients with ischemic stroke. CRS of the frontal, anterior/posterior ethmoid, and sphenoid sinuses has a directional relationship with ischemic stroke. Our results on which sinuses correlate with stroke advocate for the active surveillance of CRS in patients at high risk of ischemic stroke.

Improvements in Resistive and Capacitive Switching Behaviors in Ga2O3 Memristors via High-Temperature Annealing Process.

This study investigates the effect of a high-temperature annealing process on the characteristics and performance of a memristor based on a Ag/Ga2O3/Pt structure. Through X-ray diffraction analysis, successful phase conversion from amorphous Ga2O3 to ß-Ga2O3 is confirmed, attributed to an increase in grain size and recrystallization induced by annealing. X-ray photoelectron spectroscopy analysis revealed a higher oxygen vacancy in annealed Ga2O3 thin films, which is crucial for conductive filament formation and charge transport in memristors. Films with abundant oxygen vacancies exhibit decreased set voltages and increased capacitance in a low-resistive state, enabling easy capacitance control depending on channel presence. In addition, an excellent memory device with a high on/off ratio can be implemented due to the reduction of leakage current due to recrystallization. Therefore, it is possible to manufacture a thin film suitable for a memristor by increasing the oxygen vacancy in the Ga2O3 film while improving the overall crystallinity through the annealing process. This study highlights the significance of annealing in modulating capacitance and high-resistive/low-resistive state properties of Ga2O3 memristors, contributing to optimizing device design and performance. This study underscores the significance of high-temperature annealing in improving the channel-switching characteristics of Ga2O3-based memristors, which is crucial for the development of low-power, high-efficiency memory device.

Singular entry point technique for forehead and temple filler augmentation: Anatomical and clinical perspectives.

BACKGROUND: The depressed volume of the forehead and temple is resolved by filler injection. However, the current method has the potential to cause pain and side effects in patients, depending on the skill of the clinician. Therefore, this study proposes a new method for safer and simpler injection using only one injection entry point. METHODS: Using the novel injection method, the filler was injected into the forehead and temple regions in three unembalmed cadavers and two healthy Korean volunteers. The cannula and filler locations were identified using dissection, ultrasonography, and three-dimensional (3D) scanning. RESULTS: Ultrasonographic images and dissection results showed that the filler injected into the cadavers was in the target layer. The cannula and filler were located on the layer as the supraperiosteal layer on the forehead and the supra deep temporal fascia layer in the temple. Finally, 3D scanning images showed that the filler was injected precisely and effectively into the forehead and temples of the volunteer who underwent the procedure. CONCLUSIONS: This method can reduce pain and minimize externally visible wounds caused by injections. The injected filler was naturally connected from the forehead to the temple and maintained for around 3 months. Additionally, it is possible to inject fillers into the forehead and temple at a constant and safe depth without requiring specific skills. It is expected that this method will become a universal method because it minimizes the burden on both patients and clinicians.

A Novel Zwitterion Incorporated Nano-Crystalline Ceramic and Polymer for Bacterial Resistant Dental CAD-CAM Block.

OBJECTIVES: To create bacteria-resistant dental CAD-CAM blocks with a biofilm-resistant effect by incorporating Nano-crystalline ceramic and polymer (NCP) with 2-methacryloyloxyethyl phosphorylcholine (MPC) and sulfobetaine methacrylate (SBMA) and at an equimolar ratio, referred to as MS. METHODS: Experimental groups comprised NCP blocks containing zwitterions at 0.15wt% (MS015) and 0.45wt% (MS045). NCP blocks without MS served as control (CTRL). Flexural strength, surface hardness, water sorption and solubility, photometric properties, and cytotoxicity were assessed for all samples. Additionally, the resistance to single and multi-species bacterial adhesion was investigated. RESULTS: MS045 showed significant reduction in flexural strength (P < 0.01) compared to both CTRL and MS015. Both MS015 and MS045 showed significantly increased water sorption and significant reduction in water solubility compared to CTRL. Light transmission remained consistent across all MS content levels, but the irradiance value decreased by 12% in the MS045 group compared to the MS015 group. Notably, compared to the CTRL group, the MS015 group exhibited enhanced resistance to adhesion by Porphyromonas gingivalis and a multi-species salivary biofilm, with biofilm thickness and biomass reduced by 45% and 56%, respectively. CONCLUSIONS: NCP containing 0.15% MS can effectively reduce adhesion of multiple species of bacteria while maintaining physical and mechanical properties. CLINICAL SIGNIFICANCE: NCP integrating zwitterions is clinically advantageous in resisting bacterial adhesion at internal and external margins of milled indirect restoration.

Commemoration of body donors in a religiously diverse society: A tale of two Korean medical schools.

Although a diversity of religions exists in South Korea, with Buddhism and Christianity (Protestantism and Catholicism) being the two main faiths, Korean beliefs are deeply rooted in Confucianism. Despite the notion that the Confucian norm of filial piety discourages body donation to medical science, there has been a mindset shift in favor of body donation, driven by a heightened awareness of the body bequest programs and the care and dignity accorded to the altruistic body donors, together with the institution of commemorative services to honor them. As spirituality and religion are known to be factors that influence body donation, how religious- and non-religious-based memorial services are held to honor the donors as exemplified by two Korean medical schools-from a public university with no religious affiliation and from a Protestant-based university-are described here. The key concept of expressing gratitude and respect for the donors and their family members has positively impacted body bequest programs in this multi-religious society. Commemorative services held to pay tribute to the altruistic body donors may play an important role in inspiring a humanistic spirit in students, regardless of religious or non-religious beliefs, as exemplified by the two Korean medical schools. The takeaway here is that the elevation of spirituality in memorial services effectively resonates with society, thereby demonstrating the impact of spiritual principles independent of religious influence.

Prevalence and Characteristics of Tuberculosis in the Korean Homeless Population Based on Nationwide Tuberculosis Screening.

Background: The government of Korea implemented a strategy of prevention and early diagnosis in high-risk groups to reduce the tuberculosis (TB) burden. This study aims to investigate the TB epidemiology and gap in understanding of TB prevalence among homeless individuals by analyzing active TB chest X-ray (CXR) screening results in Korea. Methods: The Korean National Tuberculosis Association conducted active TB screening with CXR for homeless groups from January 1 to December 31, 2021. Sputum acid fast bacilli smear and culture were performed for the subjects suggestive of TB on CXR. We performed a cross-sectional analysis of the data in comparison with the national health screening results from the general population. Results: Among 17,713 homeless persons, 40 (0.23%), 3,077 (17.37%), and 79 (0.45%) were categorized as suggested TB, inactive TB, and observation required, respectively. Prevalence of suggested TB in the homeless was significantly higher (3-5 fold) than in the national general health screening based on age category (p < 0.005). Twenty-nine cases were confirmed as TB, yielding a prevalence of 164 cases per 100,000 individuals; 19 of these 29 cases showed inactive TB on CXR. Body mass index (p = 0.0478) and CXR result (p < 0.001) significantly correlated with confirmed TB based on multivariable analysis. Conclusion: Nutrition status and CXR results, especially that of inactive TB, should be considered in active TB screening of the homeless population, where TB prevalence is higher than the general population.

Ultrasonographic Study of the Submandibular Gland for Botulinum Neurotoxin Injection.

BACKGROUND: Hypertrophied submandibular glands provide a bulky contour to the lower face. Botulinum neurotoxin injection methods are commonly used for facial contouring; however, no studies have suggested injection points because of the lack of delicate anatomical information on the submandibular gland. OBJECTIVE: The aim of this study was to determine the optimal injection site for botulinum neurotoxin injections in the submandibular gland. MATERIALS AND METHODS: Anatomical considerations when injecting botulinum neurotoxin into the submandibular gland were determined using ultrasonography. The thickness of the submandibular gland, its depth from the skin surface, and the location of the vascular bundle were observed bilaterally in 42 participants. Two cadavers were dissected to measure the location of the submandibular gland corresponding to the ultrasonographic observation. RESULTS: The thickest part of the submandibular gland measured 11.12 ± 2.46 in width with a depth of 4.63 ± 0.76. At the point where it crosses the line of the lateral canthus, it measured 5.53 ± 1.83 in width and 8.73 ± 1.64 in depth. CONCLUSION: The authors suggest optimal injection sites based on external anatomical landmarks. These guidelines aim to maximize the effects of botulinum neurotoxin therapy by minimizing its deleterious effects, which can be useful in clinical settings.

Prenatal opioid exposure by likelihood of exposure and risk to prenatal development: Medicaid-covered births in Wisconsin, 2010-2019.

Prenatal opioid exposure is an established public health problem, in particular among Medicaid-covered births. Yet, existing prevalence rates are plausibly underestimated. We leverage extensive linked longitudinal administrative data for all Medicaid-covered live births in Wisconsin from 2010 to 2019 to estimate a range of prevalence rates using an innovative strategy that jointly accounts for both likelihood of exposure and potential risk to prenatal development. We find that 20.8% of infants may have been prenatally exposed to opioids, with 1.7% diagnosed with neonatal abstinence syndrome and an additional 1.2% having a high combined likelihood of exposure and potential risk to prenatal development, 2.6% a moderate combined likelihood and risk, and 15.3% a low or uncertain combined likelihood and risk. We assess improvements in prevalence estimates based on our nuanced classification relative to those of prior studies. Our strategy could be broadly used to quantify the scope of the opioid crisis for pregnant populations, target interventions, and promote child health and development.

Impact of the Ventricle Size on Alzheimer's Disease Progression: A Retrospective Longitudinal Study.

Background and Purpose: Ventricle enlargement has been implicated in the pathophysiology of Alzheimer's disease (AD). We studied the relationship between ventricular size and cognitive function in patients with AD. We focused on the effect of the initial ventricle size on the rate of cognitive decline in patients with AD. Methods: A retrospective analysis of probable clinical AD participants with more than 2 magnetic resonance imaging images was performed. To measure ventricle size, we used visual rating scales of (1) Cardiovascular Health Study (CHS) score and (2) conventional linear measurement method. Results: Increased clinical dementia rating (CDR) was correlated with a decreased Mini-Mental Status Examination (MMSE) score, and increased medial temporal lobe atrophy (MTLA) and global ventricle size (p<0.001, p<0.001, p=0.021, respectively). There was a significant correlation between the change in cognitive function in the group (70%-100%ile) with a large initial ventricle size (p=0.021 for ΔCDR, p=0.01 for ΔMMSE), while the median ventricle size (30%-70%ile) showed correlation with other brain structural changes (MTLA, frontal atrophy [FA], and white matter) (p=0.036 for initial MTLA, p=0.034 for FA). Conclusions: In this study, the initial ventricle size may be a potential new imaging biomarker for initial cognitive function and clinical progression in AD. We found a relationship between the initial ventricle size and initial AD-related brain structural biomarkers.

Fourier Transform Infrared (FT-IR) Spectroscopy and Simple Algorithm Analysis for Rapid and Non-Destructive Assessment of Cotton Fiber Maturity and Crystallinity for Plant Mapping.

Information on boll distribution within a cotton plant is critical to evaluate the adaptation and response of cotton plants to environmental and biotic stress in cotton production. Cotton researchers have applied available conventional fiber measurements, such as the high volume instrument (HVI) and advanced fiber information system (AFIS), to map the location and the timing of boll development and distribution within plants and further to determine within-plant variability of cotton fiber properties. Both HVI and AFIS require numerous cotton bolls combined for the measurement. As an alternative approach, attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy was proposed to measure fiber maturity (MIR) and crystallinity (CIIR) of a sample as little as 0.5 mg lint. Extending fiber maturity and crystallinity measurement into a single boll for node-by-node mapping, FT-IR method might be advantageous due to less sampling amount compared with HVI and AFIS methods. Results showed that FT-IR technique enabled the evaluation of fiber MIR and CIIR at a boll level, which resulted in average MIR and CIIR values highly correlated with HVI micronaire (MIC) and AFIS maturity ratio (M). Hence, FT-IR technique possesses a good potential for a rapid and non-destructive node-by-node mapping of cotton boll maturity and crystallinity distribution.

Ultrasonographic examination of masticatory muscles in patients with TMJ arthralgia and headache attributed to temporomandibular disorders.

This study used ultrasonography to compare the thickness and cross-sectional area of the masticatory muscles in patients with temporomandibular joint arthralgia and investigated the differences according to sex and the co-occurrence of headache attributed to temporomandibular disorders (HATMD). The observational study comprised 100 consecutive patients with TMJ arthralgia (71 females and 29 males; mean age, 40.01 ± 17.67 years) divided into two groups: Group 1, including 86 patients with arthralgia alone (60 females; 41.15 ± 17.65 years); and Group 2, including 14 patients with concurrent arthralgia and HATMD (11 females; 33.00 ± 16.72 years). The diagnosis of TMJ arthralgia was based on the diagnostic criteria for temporomandibular disorders. The parameters of the masticatory muscles examined by ultrasonography were subjected to statistical analysis. The pain area (2.23 ± 1.75 vs. 5.79 ± 2.39, p-value = 0.002) and visual analog scale (VAS) score (3.41 ± 1.82 vs. 5.57 ± 12.14, p-value = 0.002) were significantly higher in Group 2 than in Group 1. Muscle thickness (12.58 ± 4.24 mm) and cross-sectional area (4.46 ± 2.57 cm2) were larger in the masseter muscle than in the other three masticatory muscles (p-value < 0.001). When examining sex-based differences, the thickness and area of the masseter and lower temporalis muscles were significantly larger in males (all p-value < 0.05). The area of the masseter muscle (4.67 ± 2.69 vs. 3.18 ± 0.92, p-value = 0.004) and lower temporalis muscle (3.76 ± 0.95 vs. 3.21 ± 1.02, p-value = 0.049) was significantly smaller in Group 2 than in Group 1. An increase in VAS was significantly negatively correlated with the thickness of the masseter (r = - 0.268) and lower temporalis (r = - 0.215), and the cross-sectional area of the masseter (r = - 0.329) and lower temporalis (r = - 0.293). The masseter and lower temporalis muscles were significantly thinner in females than in males, and their volumes were smaller in patients with TMJ arthralgia and HATMD than in those with TMJ arthralgia alone. HATMD and decreased masseter and lower temporalis muscle volume were associated with increased pain intensity.

Self-crossing hyaluronic acid filler with combination use of polydioxanone thread in minipig model.

INTRODUCTION: The advances of self-crossing hyaluronic acid (SC-HA) fillers combination use with polydioxanone thread in minipigs were examined for compatibility, effectiveness, and immune response. MATERIALS AND METHODS: A 12-week experiment was conducted using 6 minipigs (3 male and 3 female each) to evaluate the effects of SC-HA filler. The molecular weight of SC-HA filler was fixed at 200 kDa and alternative storage modulus of G80, G250, and G500 were examined. The procedure involved injecting SC-HA filler and polydioxanone threads into the skin tissue of anesthetized minipigs, and tissue sampling after 1 month (three minipigs), and 3 months (three minipigs) for histological staining and analysis. The immune reaction was observed during the experiment. RESULTS: The practitioner reported it was easy to inject the SC-HA filler in combination with polydioxanone threads. All four storage modulus of SC-HA fillers were injectable within the polydioxanone thread containing cannula. Also, during the procedure, there were no immune responses at the treated sites. The results of the histological tissue examination confirmed that there was no chemical interaction between SC-HA filler and the existing polydioxanone thread, and it was observed that SC-HA filler was more uniformly distributed within the tissue with lower storage modulus, resulting in a higher production of collagen in the surrounding filler. When combined with scaffold polydioxanone thread, the scaffold polydioxanone thread helped spread the filler evenly, resulting in a more evenly distributed collagen around the filler. CONCLUSION: Today, the combination therapy of filler and polydioxanone thread in one procedure is challenging due to the high viscosity of conventional fillers. However, this study confirmed that combination therapy of filler and polydioxanone thread is possible with SC-HA fillers. Additionally, it was found that polydioxanone thread does not seem to interfere with the crosslinking reaction of SC-HA filler, and if used with a higher pH of polydioxanone, it may enhance the cross-linking reaction and achieve a higher viscosity value. Finally, the study resulted in the idea of concrete as SC-HA filler and reinforcing rod for polydioxanone thread.

Changes in vaccination practices among infants after the introduction of DTaP-IPV/Hib combination vaccines.

Background: Diphtheria-tetanus-acellular pertussis, polio, and Haemophilus influenza type B (DTaP-IPV/Hib) combination vaccine was introduced as a part of the Korea National Immunization Program (NIP) on June 19, 2017. Combination vaccines can improve vaccination rates by simplifying the vaccination schedule. Objective: To explain how the introduction of DTaP-IPV/Hib in the NIP has changed vaccination practices for infants. Methods: Using a nationwide vaccine registry, the proportion of infants who completed the full recommended doses of the primary series of DTaP, IPV, and Hib (D-I-H) within 12 months of age was estimated among those born between 2013 and 2019. Among those, the proportions of those who received the same DTaP components for all 3 doses during the primary series were calculated for the 2013-2016 and the 2017-2019 birth cohorts. Those who received the same component of DTaP throughout the entire primary vaccination schedule were categorized into 3 groups by DTaP components to compare the average frequency of medical visits for vaccination. Results: A total of 2,703,822 infants were born between 2013 and 2019, of which 96.7% completed full doses of the primary D-I-H series within 12 months of age. For the 2013-2016 birth cohorts, most received DTaP-IPV-only (75.4%), while most of the 2017-2019 birth cohorts received DTaP-IPV/Hib-only (81.0%) to complete the 3 doses for primary D-I-H series. The average frequency of medical visits for vaccination showed a significant difference across the 3 groups classified by DTaP components in every birth cohort (p < 0.001). Conclusions: After the introduction of DTaP-IPV/Hib, most infants completed the primary D-I-H series with the combination vaccine and there was a significant reduction in the average number of medical visits for vaccination. Our findings provide important insights for countries considering the introduction of combination vaccines into their NIP.

Depth of the subcutaneous tissue in the nose: Application to filler injection.

INTRODUCTION: The nasal region plays a pivotal role in both facial esthetics and functionality. The use of volumizing fillers has emerged as a potential means to enhance nasal appearance. Preliminary findings from cadaveric studies have highlighted potential risks associated with deeper needle injection, leading to cartilage damage and lateral migration of filler material. Understanding the subcutaneous tissue depth is crucial to prevent such complications and ensure safe filler placement guided by anatomical knowledge. METHODS: This study aimed to employ ultrasonographic assessment to precisely measure the depth of soft tissue in the nasal area. Fifty-two participants without prior nasal surgery or filler injections underwent detailed ultrasonographic evaluation, focusing on seven key anatomical points: Glabellar, Sellion, Rhinion, between Rhinion and Pronasal, Pronasal, between Pronasal and Subnasal, and Subnasal. RESULTS: The ultrasonographic observation revealed varying depths of subcutaneous tissue across these points: Glabellar (4.11 ± 0.79), Sellion (5.21 ± 0.97), Rhinion (2.02 ± 0.74), Rhinion to Pronasal midpoint (6.45 ± 3.1), Pronasal (9.5 ± 2.2), between Pronasal and Subnasal (8.8 ± 0.8), and Subnasal (8.5 ± 0.5). DISCUSSION: The discussion underscores the significance of understanding subcutaneous tissue depth in guiding needle length and approach angles during filler injections. This knowledge aids in achieving effective filling while ensuring safe placement within the subcutaneous tissue.

Impact of nano- and micro-sized polystyrene beads on larval survival and growth of the Pacific oyster Crassostrea gigas.

This study successionally monitored how nano- and micro-sized polystyrene beads (MNPs) influence larval mortality, growth, and attachment behavior of the Pacific oyster Crassostrea gigas related to MNP diameter and concentration. D-shaped larvae were sequentially exposed to three-diameter MNPs (0.55, 3.00, 6.00 µm) at five concentrations (0, 0.1, 1.0, 10, 20 µg/mL), and their mortality, growth stages and attachment were observed daily until they die. In addition, MNP intake and accumulation in larvae at each growth stage were determined using fluorescent beads. Deterioration in larval growth and survival was observed under all the exposure conditions, while significant negative effects on the growth parameters were defined with smaller MNPs at lower concentrations. Fluorescent signals were detected in larval digestive tracts at all except D-shaped larval stage, and on the mantle and foot in pediveligers. Therefore, MNP intake adversely affects larval physiological conditions by the synchronal effects of MNP size and concentration. Our findings highlight the implications of MNP characteristics on Pacific oyster larvae, emphasizing the interplay between size, concentration, and physiological responses, crucial for mitigating nanoparticle pollution in marine ecosystems.

Comparison of ultrasonography-based masticatory muscle thickness between temporomandibular disorders bruxers and temporomandibular disorders non-bruxers.

To compare masticatory muscle thickness in patients with temporomandibular disorders (TMDs) during rest and clenching, and by body position, using ultrasonography. This prospective study included 96 patients with TMD (67 females, 29 males; mean age: 40.41 ± 17.88 years): group 1, comprising 66 patients with TMD without bruxism (TMD_nonbruxer), and group 2, comprising 30 patients with concurrent TMD and bruxism (TMD_bruxer). In patients with TMD, bruxism was correlated with the presence of tinnitus, muscle stiffness, sleep problems, psychological stress, and restricted mouth opening. The masseter muscle significantly thickened during clenching (11.16 ± 3.03 mm vs 14.04 ± 3.47 mm, p < 0.001), whereas the temporalis muscle showed no significant increase in thickness from resting to clenching in an upright position (7.91 ± 1.98 vs 8.39 ± 2.08, p = 0.103). Similarly, during clenching in the supine position, the masseter muscle was significantly thicker compared with rest (11.24 ± 2.42 vs 13.49 ± 3.09, p < 0.001), but no significant difference was observed in temporal muscle thickness (8.21 ± 2.16 vs 8.43 ± 1.94, p = 0.464). In comparison between two groups, the average thickness of the masseter muscle was greater among TMD_bruxers than among TMD_nonbruxers in both the upright and supine positions (all p < 0.05). In the generalized lineal model, female sex (B = - 1.018, 95% confidence interval [CI] - 1.855 to - 0.181, p = 0.017) and bruxism (B = 0.868, 95% CI 0.567 to 1.169, p = 0.048) significantly predicted changes in masseter muscle thickness. Female sex (B = - 0.201, 95% CI - 0.299 to - 0.103, p = 0.011), increased age (B = - 0.003, 95% CI - 0.005 to 0.000, p = 0.038), and muscle stiffness (B = - 1.373, 95% CI - 2.369 to - 0.376, p = 0.007) were linked to decreased temporal muscle thickness. Comparing TMD nonbruxer and bruxer muscle thicknesses in upright and supine positions revealed significant increased thickness in the masseter muscle during clenching but not in the temporalis muscle. Masseter muscle thickness varied significantly by sex, body position, and resting/clenching, notably influenced by bruxism. These findings emphasize the relevance of these factors in clinical examinations of patients with TMD.