In-vitro studies are essential for understanding cellular responses, but traditional culture systems often neglect the three-dimensional (3D) structure of real implants, leading to limitations in cellular recruitment and behavior largely governed by gravity. The objective of this study was to pioneer a novel 3D dynamic osteoblastic culture system for assessing the biological capabilities of dental implants in a more clinically and physiologically relevant manner. Rat bone marrow-derived osteoblasts were cultured in a 24-well dish with a vertically positioned dental implant. Controlled rotation using a 3D rotator with 3° tilts was applied. Cell attachment, proliferation, and differentiation on implant surfaces were evaluated in response to different surface topographies, physicochemical properties, and local environments. Among the tested rotational speeds (0, 10, 30, 50 rpm), optimal osteoblast attachment and proliferation were observed at 30 rpm. A linear correlation was found between cell attachment and rotation speed up to 30 rpm, declining at 50 rpm. Alkaline phosphatase (ALP) activity and mineralized matrix formation were elevated on newly acid-etched, hydrophilic surfaces compared to their 4-week-old hydrophobic surfaces. Sandblasted implants showed higher ALP activity and matrix mineralization. Adding N-acetyl cysteine to the culture medium increased ALP activity and mineralization. Osteoblasts successfully attached, proliferated, and mineralized on dental implants in vitro under optimized dynamic conditions. This system differentiated the biological capabilities of implants with varying surface topographies, wettability, and biochemically modulated environments. These findings support developing a 3D dynamic dental implant culture model, advancing osseointegration research and innovating dental implant designs.

Periodontitis has been documented to increase the risk of diabetic nephropathy. However, the specific mechanisms through which periodontitis affects renal function remain unclear. This study aimed to investigate the mechanism by which an inflammatory reaction stimulated by periodontal pathogens affects mesangial cell fibrosis under hyperglycemic conditions in vitro. Murine mesangial cells were stimulated with 1,000 ng/mL of Porphyromonas gingivalis-derived lipopolysaccharide (PgLPS) in a control or high glucose (HG) medium. Activation of the extracellular signal-regulated kinase (ERK1/2) and expression of alpha-smooth muscle actin (α-SMA) and collagen type 1a2 (Col1a2) were analyzed for fibrosis and transformation via the transforming growth factor (TGF)-β1/Smad signaling pathway. PgLPS stimulation significantly upregulated TGF-β1 expression and Smad3 phosphorylation in the HG group compared to the control group. Additionally, activation of ERK1/2 and expression of Col1a2 and α-SMA were significantly elevated in the HG group compared to the control following PgLPS stimulation. The TGF-β1 inhibitor significantly suppressed Smad3 phosphorylation and mRNA expression of Col1a2 in the HG group. Under HG conditions, PgLPS may aggravate fibrosis in mesangial cells via the TGF-β1/Smad signaling pathway, leading to nephrosclerotic modifications. The presented study may support the association between periodontitis and chronic kidney disease, mediated by hyperglycemia.

Objectives: To investigate the effect of continuous noise generated during dental treatment on dentists’ performance and stress responses. Methods: This study involved a questionnaire survey and an experimental investigation. The questionnaire survey was conducted with 44 dentists to assess dental noise-related subjective burden and noise sources perceived as the most uncomfortable. In the experimental phase, a randomized crossover trial was performed with 11 participants under silent and noisy conditions. Work performance was evaluated using the total number of calculations (work volume) and error rates in the Uchida-Kraepelin test. Saliva samples were collected before, during, and after the test, and salivary alpha-amylase (sAA), chromogranin A (CgA), and secretory immunoglobulin A (sIgA) levels were measured to assess stress responses. Results: In the questionnaire survey, clinical noise was perceived as uncomfortable by 93.2% of dentists, with the extraoral suction unit being identified as the most unpleasant device (equivalent continuous noise level: 91.7 ± 0.6 dBA). In the randomized crossover trial, work volume in the Uchida-Kraepelin test significantly decreased, and the error rates significantly increased, under the noisy condition. With respect to salivary stress markers, sAA levels were significantly higher under the noisy condition, and sIgA levels were significantly increased. By contrast, CgA levels did not significantly differ between the conditions. Furthermore, sAA levels were significantly correlated with work performance. Conclusions: Dental noise reduced dentists’ performance and elicited stress responses. These findings highlight the need for noise mitigation and occupational stress management strategies in dental practice.

Background: Low-level laser irradiation (LLLI) can promote wound healing. However, the biological effects of the erbium-doped yttrium aluminum garnet (Er:YAG) laser on gingival wound healing remain unclear. Objectives: To assess the effects of low-level Er:YAG laser irradiation on endothelial cell activity in vitro and on early phase gingival wound healing in vivo. Methods: In vitro, human umbilical vein endothelial cells were irradiated with a low-level Er:YAG laser (30 mJ/pulse, 10 Hz, 20 and 30 s, defocused, no water spray) and assessed for viability, cytotoxicity, and migration. Standardized bilateral wounds (4 × 1 mm) were created in the palatal gingiva of 14 male mice using a scalpel and curette. The wounds were irradiated for 20 s under the same irradiation settings, using a contact tip (diameter 800 μm) to induce superficial blood surface coagulation, while contralateral sites were assigned to controls in a split-mouth design. Postoperative wound area and mRNA expression of IL-6, TNF-α, VEGF, FGF-2, and TGF-β1 were analyzed after 48 h. Results: In vitro, LLLI significantly enhanced cell proliferation with/without increasing cytotoxicity. In the wound healing assay, the LLLI significantly promoted cell migration compared with the control. In vivo, the reduction in residual wound area in the laser group was comparable to that in the control group. IL-6 and TNF-α expressions were significantly downregulated, whereas VEGF was significantly upregulated in the laser group. Conclusions: Low-level Er:YAG laser irradiation enhances anti-inflammatory and pro-angiogenic effects, suggesting its potential in promoting gingival wound healing.