Tien-Min Gabriel Chu

Purpose: To assess the fracture load at the tooth‐denture base interface in dentures fabricated using three different production methods: compression mold, computer‐aided design and computer‐aided manufacturing (CAD‐CAM) milled (monolithic and bonded), and 3D‐ printed dentures (monolithic and bonded). Materials and Methods: Seven groups ( n = 10/group) were fabricated using a standardized segmented digital denture design that included tooth #8. Fabrication techniques included conventional compression molding, single, two‐disc milling or with bonded tooth designs, and 3D printing monolithic or with bonded tooth designs, utilizing either prefabricated, milled, or 3D‐printed teeth. Specimens were embedded in cylindrical molds exposing 2 mm of the denture base and subjected to fracture load testing. Failure modes were analyzed via scanning electron microscopy and classified as adhesive, cohesive, or mixed. One‐way analysis of variance with Fisher's LSD was used to compare fracture loads among groups. Results: Statistical analysis revealed significant differences in fracture load among the seven denture fabrication methods ( p < 0.001). The monolithic milled group demonstrated the highest fracture load (504.7 ± 76 N) and reliability, as confirmed by Weibull analysis. Both 3D‐printed denture bases with bonded teeth groups also showed high fracture load values (361.2 ± 0.4 and 348.7 ± 0.8 N, respectively), outperforming the conventional group ( p < 0.001, p = 0.002). Milled base with bonded milled tooth and monolithic print exhibited moderate fracture load. In contrast, compression‐molded and milled base with bonded prefabricated tooth exhibited the lowest fracture load (251.7 ± 69.6 and 232.8 ± 47.7 N, respectively). Fracture modes varied, with cohesive failures more evident in stronger groups and adhesive or mixed failures in weaker ones. Conclusion: Denture fabrication method had a significant effect on tooth–base fracture load. Monolithic CAD‐CAM‐milled denture outperformed all other groups in denture teeth fracture load. 3D‐printed techniques with optimized bonding also achieved high fracture load exceeding conventional compression‐molded dentures.

Purpose: To investigate the translucency of the new 3D‐printable materials concerning thickness and the color masking ability of each material against different substrate colors. Materials and Methods: Ninety square‐shaped specimens (12.0 mm × 12.0 mm) of two new 3D‐printable materials: ceramic‐infiltrated hybrid resin composite (VS) and light‐polymerizing resin (FX), and a control group, lithium disilicate (LS), were fabricated at three different thicknesses (1.0, 2.0, and 3.0 mm). Ten samples ( n = 10) were fabricated per material‐thickness combination. Three substrates (12.0 mm × 12.0 mm × 2.0 mm) were digitally designed and milled from cobalt‐chromium (Co‐Cr) alloy (silver color), noble alloy (gold color), and zirconia (tooth color). The color parameters L *, a *, and b * in the CIELab color space of all specimens were measured, and the translucency parameters (TP ₀₀ ) were calculated with the CIEDE2000 formula. Color differences (dE ₀₀ ) of each material at three different thicknesses against three different substrates were measured and calculated with the CIEDE2000 formula. The influence of material type and thickness on TP ₀₀ was analyzed using two‐way analysis of variance (ANOVA), and color differences (dE00) were evaluated with three‐way ANOVA for material, substrate, and thickness, with additional two‐way ANOVAs for pairwise substrate comparisons; one‐sided one‐sample t ‐tests tested dE00 against the perceptibility (PT = 1.0) and acceptability (AT = 2.7) thresholds, and Fisher's protected least significant difference test was used for pairwise comparisons ( α = 0.05). Results: Increasing sample thickness resulted in reduced translucency for all materials. Interactions between sample thickness and materials impacted both translucency and color masking ability. One‐millimeter LS samples demonstrated the highest translucency (and lowest color masking ability), while 1.0 and 2.0 mm samples of VS and FX, and 2.0 mm samples of LS, exhibited similar translucency. The greatest change in color masking ability was observed when the thickness was increased from 1.0 to 3.0 mm for all materials. For LS against the zirconia substrate, the most substantial change occurred between 1.0 and 2.0 mm. In general, against the zirconia and gold alloy substrates, color masking was optimized at 2.0 mm, although a gradual and less pronounced increase continued up to 3.0 mm. A more consistent stepwise increase in color masking ability was observed for all materials as sample thickness increased from 1.0 to 2.0 mm and then to 3.0 mm against the Co‐Cr substrate. Conclusions: LS may be superior and represent the material of choice clinically when esthetics is the primary concern, when compared to the new 3D‐printable materials. Each material tested demonstrated the potential to achieve desirable translucency and effective masking, dependent upon both material thickness and the underlying substrate. Clinical decisions regarding the utilization of these materials should be guided by specific requirements of each restoration, with careful consideration of both mechanical and esthetic properties.

Soft tissue manipulation (STM) is widely used by physical therapists, massage therapists, athletic trainers, and osteopathic physicians to manage musculoskeletal pain, yet its biological mechanisms remain poorly understood. Preclinical studies indicate that STM can alter immune cell behavior in animal models, increasing anti-inflammatory cytokines (IL-4, IL-10) and reducing chemokines such as RANTES/CCL5. Single-cell transcriptomic analyses suggest mechanical treatment may reprogram stromal cells and shift immune cell recruitment in aged or inflamed tissues. However, many of these mechanistic findings have yet to be confirmed in human studies. Early clinical trials show massage therapy can modify circulating leukocytes and reduce cytokine responses, but direct tissue-level evidence in human subjects remains limited. This narrative review summarizes existing insights and emphasizes the need for future clinical investigations targeting populations with chronic inflammation, repetitive-use injuries, post-surgical fibrosis, or age-related muscle decline. We advocate for studies incorporating tissue or fluid sampling, cytokine profiling, and molecular assays such as flow cytometry or transcriptomics to characterize STM’s immunological effects in people. Rather than simply easing symptoms, STM may act as a precision mechanical stimulus that recalibrates immune tone and promotes tissue repair. Bridging basic science with clinical research will be essential to establish STM as a biologically informed, mechanobiology-based therapeutic strategy.

Soft tissue manipulation (STM) is widely used by physical therapists, massage therapists, athletic trainers, and osteopathic physicians to manage musculoskeletal pain, yet its biological mechanisms remain poorly understood. Preclinical studies indicate that STM can alter immune cell behavior in animal models, increasing anti-inflammatory cytokines (IL 4, IL 10) and reducing chemokines such as RANTES/CCL5. Single-cell transcriptomic analyses suggest mechanical treatment may reprogram stromal cells and shift immune cell recruitment in aged or inflamed tissues. However, many of these mechanistic findings have yet to be confirmed in human studies. Early clinical trials show massage therapy can modify circulating leukocytes and reduce cytokine responses, but direct tissue-level evidence in human subjects remains limited. This review summarizes existing insights and emphasizes the need for future clinical investigations targeting populations with chronic inflammation, repetitive-use injuries, post-surgical fibrosis, or age-related muscle decline. We advocate for studies incorporating tissue or fluid sampling, cytokine profiling, and molecular assays such as flow cytometry or transcriptomics to characterize STM’s immunological effects in people. Rather than simply easing symptoms, STM may act as a precision mechanical stimulus that recalibrates immune tone and promotes tissue repair. Bridging basic science with clinical research will be essential to establish STM as a biologically informed, mechanobiology based therapeutic strategy.

Purpose: To compare the trueness of artificial intelligence (AI)‐based, manual, and global segmentation protocols by superimposing the resulting segmented 3D models onto reference gold standard surface scan models. Materials and Methods: Twelve dry human mandibles were used. A cone beam computed tomography (CBCT) scanner was used to scan the mandibles, and the acquired digital imaging and communications in medicine (DICOM) files were segmented using three protocols: global thresholding, manual, and AI‐based segmentation (Diagnocat; Diagnocat, San Francisco, CA). The segmented files were exported as study 3D models. A structured light surface scanner (GoSCAN Spark; Creaform 3D, Levis, Canada) was used to scan all mandibles, and the resulting reference 3D models were exported. The study 3D models were compared with the respective reference 3D models by using a mesh comparison software (Geomagic Design X; 3D Systems Inc, Rock Hill, SC). Root mean square (RMS) error values were recorded to measure the magnitude of deviation (trueness), and color maps were obtained to visualize the differences. Comparisons of the trueness of three segmentation methods for differences in RMS were made using repeated measures analysis of variance (ANOVA). A two‐sided 5% significance level was used for all tests in the software program. Results: AI‐based segmentations had significantly higher RMS values than manual segmentations for the entire mandible ( p < 0.001), alveolar process ( p < 0.001), and body of the mandible ( p < 0.001). AI‐based segmentations had significantly lower RMS values than manual segmentations for the condyles ( p = 0.018) and ramus ( p = 0.013). No significant differences were found between the AI‐based and manual segmentations for the coronoid process ( p = 0.275), symphysis ( p = 0.346), and angle of the mandible ( p = 0.344). Global thresholding had significantly higher RMS values than manual segmentations for the alveolus ( p < 0.001), angle of the mandible ( p < 0.001), body of the mandible ( p < 0.001), condyles (p < 0.001), coronoid ( p = 0.002), entire mandible ( p < 0.001), ramus ( p < 0.001), and symphysis ( p < 0.001). Global thresholding had significantly higher RMS values than AI‐based segmentation for the alveolar process ( p = 0.002), angle of the mandible ( p < 0.001), body of the mandible ( p < 0.001), condyles ( p < 0.001), coronoid ( p = 0.017), mandible ( p < 0.001), ramus ( p < 0.001), and symphysis ( p < 0.001). Conclusion: AI‐based segmentations produced lower RMS values, indicating truer 3D models, compared to global thresholding, and showed no significant differences in some areas compared to manual segmentation. Thus, AI‐based segmentation offers a level of segmentation trueness acceptable for use as an alternative to manual or global thresholding segmentation protocols.

Achieving bone union remains a significant clinical dilemma. The use of osteoinductive agents, specifically bone morphogenetic proteins (BMPs), has gained wide attention. However, multiple side effects, including increased incidence of cancer, have renewed interest in investigating alternatives that provide safer, yet effective bone regeneration. Here we demonstrate the robust bone healing capabilities of the main megakaryocyte (MK) growth factor, thrombopoietin (TPO), and second-generation TPO agents using multiple animal models, including mice, rats, and pigs. This bone healing activity is shown in two fracture models (critical-sized defect [CSD] and closed fracture) and with local or systemic administration. Our transcriptomic analyses, cellular studies, and protein arrays demonstrate that TPO enhances multiple cellular processes important to fracture healing, particularly angiogenesis, which is required for bone union. Finally, the therapeutic potential of thrombopoietic agents is high since they are used in the clinic for other indications (eg, thrombocytopenia) with established safety profiles and act upon a narrowly defined population of cells.

Purpose: To explore the impact of zirconia types, coloring methods, and surface finishing on the color stability of monolithic multilayered polychromatic zirconia after artificial aging, including thermocycling and simulated toothbrushing. Materials and Methods: Eighty square‐shaped zirconia samples were divided into 2 types (M3Y‐TZP and M6Y‐PSZ), further categorized based on coloring methods (precolored and extrinsically colored) and surface finishing techniques (mechanical polishing or glazing). The color stability was assessed using the CIEDE2000 formula. Artificial aging was simulated via thermocycling and toothbrushing. All samples were analyzed with a spectrophotometer to determine the post‐aging color changes (Δ E ₀₀ ). The Δ E ₀₀ were interpreted and classified using the 50:50% perceptibility threshold (PT) and the 50:50% acceptability threshold (AT). Comparisons between groups for Δ E ₀₀ differences were performed using three‐way ANOVA, with pairwise comparisons facilitated by Fisher's protected least significant difference test, α = 0.05. Results: The study results indicated significant impacts of zirconia type, coloring method, and surface finishing on color stability. The M6Y groups experienced significantly greater color changes (6.61 ± 1.63) compared to the M3Y groups (3.40 ± 2.24), p < 0.0001. For both types of zirconia, extrinsically colored samples exhibited significantly higher Δ E ₀₀ when mechanically polished ( p = 0.004). However, surface finishing had no significant effect on Δ E ₀₀ in precolored samples of either zirconia material ( p = 1.000). The evaluation and categorization of Δ E ₀₀ variations indicated that nearly all color changes in the M6Y groups, regardless of being precolored, extrinsically colored, polished, or glazed, were deemed extremely unacceptable (Grade 1). In contrast, the M3Y groups showed more acceptable results, with the majority of color changes classified as moderately unacceptable (Grade 3). Conclusions: The color stability of multilayered polychromatic zirconia is influenced by the type of material, extrinsic coloring, and the chosen surface treatment post‐artificial aging. The translucent 6Y‐PSZ exhibited lower color stability, especially with only mechanical polishing. For the fabrication of M3Y‐TZP and 6Y‐PSZ monolithic multilayered polychromatic zirconia restorations, extrinsic coloring should be paired with glazing to maintain color stability. Conversely, in the absence of extrinsic coloring, both glazing and mechanical polishing are effective in preserving color stability.

Purpose: To examine the color stability of 3D‐printed and milled, interim, and definitive, restorative materials after immersion in artificial saliva and wine for 1, 3, and 6 months. Material and Methods: The study used a 2 × 5 factorial design with 10 subgroups, including 2 immersion liquids (artificial saliva and wine) and 5 manufacturing technology and restorative material combinations ( n = 10). Color measurements were taken using a contact‐type digital spectrophotometer (CM‐2600d Spectrophotometer; Konica Minolta Healthcare Americas Inc) before immersion and at 1 month (T1), 3 months (T3), and 6 months (T6) after immersion. The CIE2000 system was used to calculate quantitative measurements of color differences in ΔE ₀₀ , and comparisons were made to the acceptability threshold (AT) and perceptibility threshold (PT). Repeated measures of ANOVA ( α = 0.05) were used to compare differences in color changes between manufacturing technology/restorative material‐immersion liquid combinations at T1, T3, and T6. Results: To compare the effect of immersion liquid and time on the manufacturing technology/restorative material groups, the ΔE ₀₀ values were compared to the PT of 0.8 and the AT of 1.8. Wine caused significant color changes in ΔE ₀₀ values beyond the PT and AT values in all groups at all time intervals, except for the AT value of milled definitive crowns (hybrid nano‐ceramic material). Wine immersion caused significant ΔE ₀₀ for all manufacturing technology/restorative material groups at all time intervals (1 month, 3 months, and 6 months) when compared to artificial saliva immersion (all p < 0.001). Conclusion: Upon exposure to artificial saliva, 80%–100% of samples from all groups remained within the acceptable and perceptible color change thresholds. The wine had significant chromogenic effects on all tested restorative materials, however, the milled definitive crowns (hybrid nano‐ceramic material) showed the greatest color stability. For patients with heavy wine consumption, 3D‐printed definitive crowns (hybrid ceramic‐filled material) may show discoloration exceeding acceptable and perceptible color change limits.