Development of an Aged Full-Thickness Skin Model Using Flexible Skin-on-a-Chip Subjected to Mechanical Stimulus Reflecting the Circadian Rhythm.

The skin is subject to both intrinsic aging caused by metabolic processes in the body and extrinsic aging caused by exposure to environmental factors. Intrinsic aging is an important obstacle to in vitro experimentation as its long-term progression is difficult to replicate. Here, we accelerated aging of a full-thickness skin equivalent by applying periodic mechanical stimulation, replicating the circadian rhythm for 28 days. This aging skin model was developed by culturing a full-thickness, three-dimensional skin equivalent with human fibroblasts and keratinocytes to produce flexible skin-on-a-chip. Accelerated aging associated with periodic compressive stress was evidenced by reductions in the epidermal layer thickness, contraction rate, and secretion of Myb. Increases in ß-galactosidase gene expression and secretion of reactive oxygen species and transforming growth factor-ß1 were also observed. This in vitro aging skin model is expected to greatly accelerate drug development for skin diseases and cosmetics that cannot be tested on animals.

Testing the Effectiveness of Curcuma longa Leaf Extract on a Skin Equivalent Using a Pumpless Skin-on-a-Chip Model.

The in vitro tests in current research employ simple culture methods that fail to mimic the real human tissue. In this study, we report drug testing with a 'pumpless skin-on-a-chip' that mimics the structural and functional responses of human skin. This model is a skin equivalent constituting two layers of the skin, dermis and epidermis, developed using human primary fibroblasts and keratinocytes. Using the gravity flow device system, the medium was rotated at an angle of 15 degrees on both sides so as to circulate through the pumpless skin-on-a-chip microfluidic channel. This pumpless skin-on-a-chip is composed of upper and lower chips, and is manufactured using porous membranes so that medium can be diffused and supplied to the skin equivalent. Drug testing was performed using Curcuma longa leaf extract (CLLE), a natural product cosmetic ingredient, to evaluate the usefulness of the chip and the efficacy of the cosmetic ingredient. It was found that the skin barrier function of the skin epidermis layer is enhanced to exhibit antiaging effects. This result indicates that the pumpless skin-on-a-chip model can be potentially used not only in the cosmetics and pharmaceutical industries but also in clinical applications as an alternative to animal studies.

The Potential of Percent Agreement as an Adjunctive Diagnostic Tool for Acute Temporomandibular Disorder.

Background/Objectives: It is well established that individuals with chronic temporomandibular disorder (TMD) exhibit differences in their physical and psychosocial characteristics from those with acute TMD. However, few studies have analyzed the physical and psychosocial characteristics of patients with acute TMD. The objective of this cross-sectional study is twofold: first, to ascertain whether there are differences in physical and psychosocial factors among patients with acute TMD based on the percent agreement between patient-reported pain sites and pain sites identified through standardized palpation and, second, to determine the potential of percent agreement as a diagnostic and prognostic factor. Methods: We analyzed physical and psychosocial factors in 309 patients diagnosed with acute TMD. Of these, 171 patients were selected for an analysis of their response to treatment. These patients were divided into three groups based on their percent agreement: Group A (agreement under 80%), Group B (agreement 80-89%), and Group C (agreement 90% or over) in the initial analysis and Group a (agreement under 80%), Group b (agreement 80-89%), and Group c (agreement 90% or over) in the subsequent analysis. This study was approved by the Ethics Committee of Pusan National University Dental Hospital (IRB No. 2023-05-011, 25 May 2023). Results: The lower the percent agreement, the greater the parafunctional oral habits, stress, chronicity, somatization, depression, anxiety, and number of painful sites. A lower percent agreement was associated with poorer treatment outcomes. The percent agreement demonstrated a 41.2% capacity to predict residual pain after treatment. Conclusions: Clinicians can utilize percentage agreement as an adjunctive diagnostic tool to provide more suitable treatments to patients.

A Comparison of the Condyle and Articular Eminence in Asian Juvenile Idiopathic Osteoarthritis Patients with Unilateral and Bilateral TMJ Involvement: A Retrospective Case-Control Study.

This study compared the condylar volume, length, and articular eminence (AE) characteristics of normal individuals to those with unilateral and bilateral juvenile idiopathic osteoarthritis (JOA). The 116 patients were divided into four groups: Control (n = 16), affected condyle of unilateral JOA (Aff-Uni) (n = 36), non-affected condyle of JOA (NonAff-uni) (n = 36), and bilateral JOA (Bilateral) (n = 28). The differences in condyle volume and length and AE were analyzed using ANOVA and Bonferroni post-hoc tests. The results showed that Bilateral had a significantly different condylar volume, especially in the condylar head (p < 0.01), specifically the middle, anterior, and medial parts (p < 0.05). Condylar length also differed among the groups, with differences observed between the control group and the other three groups, as well as between the bilateral group and the other three groups (p < 0.01). AE total volume differed between the control group and Aff-Uni. In the detailed comparison, Aff-Uni and NonAff-Uni were smaller than the control group in the posterior, lateral, and medial sections (p < 0.05). In conclusion, depending on the involvement of unilateral or bilateral JOA, there were differences in condylar volume and AE when compared to the normal control group. Therefore, a prognosis should be evaluated by distinguishing between patients with unilateral and bilateral JOA.

Local Injection of Growth Hormone for Temporomandibular Joint Osteoarthritis.

PURPOSE: Osteoarthritis (OA) of the temporomandibular joint (TMJ) elicits cartilage and subchondral bone defects. Growth hormone (GH) promotes chondrocyte growth. The aim of this study was to evaluate the efficacy of intra-articular injections of GH to treat TMJ-OA. MATERIALS AND METHODS: Monosodium iodoacetate (MIA) was used to induce OA in the TMJs of rats. After confirming the induction of OA, recombinant human GH was injected into the articular cavities of rats. Concentrations of GH and IGF-1 were measured in the blood and synovial fluid, and OA grades of cartilage and subchondral bone degradation were recorded by histological examination and micro-computed tomography. RESULTS: MIA-induced OA in the rat TMJ upregulated insulin-like growth factor-1 (IGF-1) rather than GH levels. GH and IGF-1 concentrations were increased after local injection of GH, compared with controls. Locally injected GH lowered osteoarthritic scores in the cartilage and subchondral bone of the TMJ. CONCLUSION: Intra-articular injection of GH improved OA scores in rat TMJs in both cartilage and subchondral bone of the condyles without affecting condylar bone growth. These results suggest that intra-articular injection of human GH could be a suitable treatment option for TMJ-OA patients in the future.

Characteristics of patients who perceive dental treatment as a cause of oral mucosal lesions.

This retrospective study aims to investigate the proportion and characteristics of patients who perceive dental treatment (DT) as a cause of oral mucosal lesions (OMLs). A total of 2,302 patients with OMLs visited the Oral Medicine Department of Pusan National University Dental Hospital. The patients were divided into a study group (280 patients who perceived DT as a cause of OMLs) and a control group (300 randomly selected patients). Percentages of DT types, clinical characteristics, and the frequencies of diagnoses and chief complaint (CC) sites were analyzed in both groups. Among the patients with OMLs, 12.2% attributed OMLs to DT. Among the diagnoses, allergic reaction (AR) and traumatic ulcer/irritation (TU) were significantly more frequent in the study group. The DT types most frequently perceived as the cause of OMLs were implants. According to patients, TU and candida occurred most frequently following denture placement (68-79%), whereas oral lichen planus and AR occurred most commonly following implant treatment (52-53%). The gingiva was significantly more frequent as the CC site in the study group than in the control group (P < 0.05 for all outcomes). It is important to inform patients of the potential complications of DT and the importance of regular check-ups.

Pattern analysis of patients with temporomandibular disorders resulting from unilateral mastication due to chronic periodontitis.

PURPOSE: The purpose of the present study was to perform a pattern analysis in patients with temporomandibular disorder (TMD) resulting from unilateral mastication due to chronic periodontitis. METHODS: Thirty participants with signs or symptoms of TMD who engaged in unilateral mastication due to periodontitis-related discomfort (test group) were selected. Another 30 subjects exhibiting signs or symptoms of TMD resulting from unilateral mastication not due to chronic periodontitis (control group) were also recruited. An interview-based questionnaire was administered, and an examination of the temporomandibular joint (TMJ) with determination of periodontal status was performed. RESULTS: The duration of unilateral mastication was significantly longer in the control group than in the test group. There was a significant negative correlation between the duration of unilateral mastication and the Community Periodontal Index score. Using the Research Diagnostic Criteria for TMD (RDC/TMD) axis I algorithms, all the subjects were assigned to 3 main groups. The test group exhibited significantly a higher diagnostic distribution of group III (arthralgia, osteoarthritis, or osteoarthrosis), and in both the test and control groups, the number of diagnoses was larger for the non-chewing side. The control group showed a significantly higher diagnostic distribution of group I (myofacial pain), and in both the test and control groups, the number of diagnoses was larger for the chewing side. CONCLUSIONS: The results of the present study indicate that unilateral mastication due to chronic periodontitis could induce not only pain but also structural TMJ changes if adequate treatment is not administered and supported within a short time from the onset of the condition. Therefore, immediate treatment of chronic periodontitis is recommended to prevent not only the primary progress of periodontal disease, but also secondary TMJ-related problems. Furthermore, subjects who have suffered chronic long-term periodontitis without treatment should be urged to undergo a TMJ examination.