Meikai University

Leadless pacemaker (LP) implantation at the apical septum has been linked to pacing-induced cardiomyopathy (PICM). This study aimed to examine the precise position for LP implantation in the RV septum using the three-dimensional rotational angiography (3D-RA) system. The accurate implantation sites were visualized through the fluoroscopic image, and the relationship to the measured QRS duration during pacing (p-QRS duration) was investigated to evaluate their potential association with cardiomyopathy. Fifty-four patients underwent LP implantation with 3D-RA guidance. Implantation sites were assessed using the horizontal axis from the apex to the center of the tricuspid valve and the vertical axis from the inferior border of the apex to the outflow tract transition. The p-QRS durations were measured intraoperatively using electrocardiograms. Echocardiography was performed 12months later to assess PCIM progression. All 54 LPs were successfully implanted in the septum. Mean horizontal and vertical positions within the RV were 69.7±10.5% and 66.5±13.1%, respectively. Mean p-QRS duration was 148±11ms. The horizontal position was correlated with QRS duration (R=0.59), while the vertical position showed no correlation (R=0.03). The native QRS (n-QRS) duration was also an independent predictor of prolonged p-QRS duration (p=0.018). No patients developed cardiomyopathy progression on follow-up, and no association with p-QRS duration was observed. In LP implantation, the horizontal position within the RV septum correlates more strongly with p-QRS duration than vertical position. Prolonged n-QRS duration also prolonged p-QRS duration; however, further research is needed to evaluate the relationship between the implanted position and the occurrence of PICM.

Mouthguards are recommended for all sports that may cause injuries to the head and oral cavity. Custom mouthguards, made conventionally in the thermoforming process from ethylene vinyl acetate (EVA), face challenges with thinning at the incisor area during the process. In contrast, additive manufacturing (AM) processes enable the precise reproduction of the dimensions specified in a computer-aided design (CAD) model. The potential use of filament extrusion materials in the fabrication of custom mouthguards has not yet been explored in comparative studies. Our research aimed to compare five commercially available filaments for the material extrusion (MEX) also known as fused deposition modelling (FDM) of custom mouthguards using a desktop 3D printer. Samples made using Copper 3D PLActive, Spectrum Medical ABS, Braskem Bio EVA, DSM Arnitel ID 2045, and NinjaFlex were compared to EVA Erkoflex, which served as a control sample. The samples underwent tests for ultimate tensile strength (UTS), split Hopkinson pressure bar (SHPB) performance, drop-ball impact, abrasion resistance, absorption, and solubility. The results showed that Copper 3D PLActive and Spectrum Medical ABS had the highest tensile strength. DSM Arnitel ID 2045 had the highest dynamic property performance, measured with the SHPB and drop-ball tests. On the other hand, NinjaFlex exhibited the lowest abrasion resistance and the highest absorption and solubility. DSM Arnitel ID 2045's absorption and solubility levels were comparable to those of EVA, but had significantly lower abrasion resistance. Ultimately, DSM Arnitel ID 2045 is recommended as the best filament for 3D-printing mouthguards. The properties of this biocompatible material ensure high-impact energy absorption while maintaining low fluid sorption and solubility, supporting its safe intra-oral application for mouthguard fabrication. However, its low abrasion resistance indicated that mouthguards made from this material may need to be replaced more frequently.

BackgroundPeriodontal inflamed surface area (PISA) and masticatory efficiency have been used to evaluate the relationship between systemic diseases and oral diseases. However, clear standards for PISA values and masticatory efficiency in relation to the severity of periodontitis are lacking. This study aims to evaluate PISA values and masticatory efficiency based on the 2018 periodontal status classification system.MethodsIn total, 153 healthy participants diagnosed with periodontitis were included in the study. The diagnosis was based on the 2018 periodontal status classification. PISA values and masticatory efficiency were measured at baseline and after initial periodontal therapy.ResultsPISA demonstrated a higher area under the curve for Stage III (0.815) and Grade B (0.85). At baseline, PISA was showed significant negative correlation with masticatory efficiency (B coefficient [95% CI]: -0.02 [-0.03, -0.006], p < 0.01). Following periodontal therapy, both PISA values and masticatory efficiency showed significant improvements, with median PISA values changing from 856 at baseline to 277.5 after treatment, and mean masticatory efficiency increasing from 153.3 to 166.9. After initial periodontal therapy, PISA values were significantly higher in patients classified as Stage IV and Grade C compared to those with other stages and grades. Age exhibited a significant negative correlation with changes in PISA (B coefficient [95%CI]: -11.8 [-20.3, -3.19]), and change in PISA value was significantly positively related to the increase in masticatory efficiency (B coefficient [95%CI], 0.02 [(0.0002, 0.03]). In patients with periodontitis, changes in periodontitis classification were associated with increased PISA values and decreased masticatory efficiency.ConclusionPeriodontal therapy improved PISA and masticatory efficiency values. However, the extent of improvement was less pronounced in patients with higher stages and grades of periodontitis. It is essential to consider the interplay between increased PISA and decreased masticatory efficiency when treating patients with severe periodontitis.

The culture systems for dental pulp cells are contributing to the development of vital pulp therapy. In general, 2-dimensional (2D) monolayer culture systems are typically adopted to analyze the mechanisms underlying dental pulp cell differentiation. However, several limitations exist to reproducing the natural micro-environment of dental pulp tissue using such 2D culture systems. The aim of the present study was to establish a 3-dimensional (3D) culture system for dental pulp cells using atelocollagen gel and to determine whether the resulting 3D culture system can be used examine the effects of Wnt10a on dentinogenesis. The dental pulp cells were isolated from rat lower incisors and mixed into atelocollagen gel with recombinant Wnt10a (Wnt group) or phosphate-buffered saline (Cont group) for the 3D culture system. Cells added into atelocollagen gel were cultured for 15days and mineralized nodule formation and mRNA expressions (Dentin sialophosphoprotein [Dspp], Osteocalcin [Otc], and Wnt10a) were examined. The dental pulp cells differentiated into odontoblasts forming mineralized nodules with matrix containing OTC. Real-time quantitative polymerase chain reaction revealed that 3D-cultured dental pulp cells expressed Dspp, Otc, and Wnt10a mRNAs on day 15 and Wnt group cells expressed these mRNAs more strongly than Cont group cells. We confirmed that 3D-cultured dental pulp cells differentiated into odontoblasts forming mineralized dentin nodules, and Wnt10a stimulated the formation of mineralized dentin nodules. These findings suggest that 3D culture systems are likely to prove useful for analysis of dentinogenesis and can contribute to the development of vital pulp therapy.

During secondary palate formation, bilateral palatal shelves grow vertically to a horizontal position. This morphological change of the palatal shelves, defined as the palatal shelf elevation, occurs from embryonic day (E)-13.5 to E14 in mice. Palatal shelves show regional differences in elevation patterns along the anterior-posterior (AP) axis; however, the underlying mechanisms remain unclear. Material properties of the lingual/nasal and buccal/oral surfaces, especially stiffness, possibly contribute to different elevation patterns. Indentation test using atomic force microscopy was performed to measure the stiffness at the epithelial surface of the palatal shelf. Measurement of palatal shelf stiffness along the AP axis before and after elevation revealed that the lingual/nasal surface was softer than the buccal/oral surface in the posterior region before elevation and that the palatal shelf was stiffer after elevation than before elevation. Moreover, the thickness of epithelial cells on the lingual/nasal side was lower than that on the buccal/oral side before elevation. Overall, our results suggest that epithelial cell thickness affects epithelial surface stiffness, causing regional differences in elevation patterns.

Background/AimThe aim of this study was to examine the effects of diode laser irradiation (910 nm) on bone formation in tibiae with bone defects in estrogen-deficient rats. Micro-computed tomography (micro-CT) was performed for 3-dimensional (3D) morphological evaluation of newly formed bone tissues.Materials and MethodsRats underwent sham operation (Sham) or ovariectomy (OVX), and bone defects were created in the tibiae, which were then subjected to diode laser irradiation for seven days in the laser groups (Sham-laser or OVX-laser groups). Tibiae with bone defects from Sham or OVX groups were irradiated with a guide light instead of a laser, serving as control groups (Sham-Cont or OVX-Cont groups). The tibiae were exposed to laser irradiation every day over a period of seven days. After irradiation, the tibiae underwent micro-CT, and then 3D reconstruction was performed for analysis of new bone formation.ResultsEstrogen deficiency induced osteoporosis in the tibiae of OVX rats. Laser irradiation induced greater new bone formation in the region of bone defects in both Sham- and OVX-laser groups compared to the Sham- and OVX-Cont groups, respectively. No significant difference in the volume of new bone formation was seen between Sham- and OVX-laser groups.ConclusionLaser irradiation could induce new bone formation in the region of bone defects in both Sham and OVX rats. This suggests that laser irradiation has potential for bone regeneration therapy in cases of postmenopausal osteoporosis.