Dental Materials最新文献_第6页

Design and optimization of a novel patient-specific subperiosteal implant additively manufactured in yttria-stabilized zirconia 用钇稳定氧化锆添加剂制造的新型患者特异性骨膜下植入物的设计与优化。

IF 4.6 1区医学 Q1 DENTISTRY, ORAL SURGERY & MEDICINE

Dental Materials

Pub Date : 2024-07-30 DOI: 10.1016/j.dental.2024.07.008

Objective

To design a patient-specific subperiosteal implant for a severely atrophic maxillary ridge using yttria-stabilized additively manufactured zirconia (3YSZ) and evaluate its material properties by applying topology optimization (TO) to replace bulk material with a lattice structure.

Materials

A contrast-based segmented skull model from anonymized computed tomography data of a patient was used for the initial anatomical design of the implant for the atrophic maxillary ridge. The implant underwent finite element analysis (FEA) and TO under different occlusal load-bearing conditions. The resulting implant designs, in bulk material and lattice, were evaluated via in-silico tensile tests and 3D printed.

Results

The workflow produced two patient-specific subperiosteal designs: a) an anatomically precise bulk implant, b) a TO lattice implant. In-silico tensile tests revealed that the Young’s modulus of yttria-stabilized zirconia is 205 GPa for the bulk material and 83.3 GPa for the lattice. Maximum principal stresses in the implant were 61.14 MPa in bulk material and 278.63 MPa in lattice, both tolerable, indicating the redesigned implant can withstand occlusal forces of 125–250 N per abutment. Furthermore, TO achieved a 13.10 % mass reduction and 208.71 % increased surface area, suggesting improved osteointegration potential.

Significance

The study demonstrates the planning and optimization of ceramic implant topology. A further iteration of the implant was successfully implanted in a patient-named use case, employing the same fabrication process and parameters.

目的使用钇稳定添加剂制造的氧化锆（3YSZ）为严重萎缩的上颌嵴设计患者专用的骨膜下种植体，并通过应用拓扑优化（TO）以晶格结构取代块状材料来评估其材料特性：根据患者的匿名计算机断层扫描数据建立了基于对比度的颅骨模型，用于上颌萎缩嵴种植体的初步解剖设计。该种植体在不同的咬合承载条件下进行了有限元分析（FEA）和TO分析。最终的种植体设计，包括块状材料和晶格，都通过了室内拉伸试验评估，并进行了三维打印：结果：该工作流程产生了两种针对特定患者的骨膜下设计：a）解剖精确的块状种植体；b）TO 格状种植体。硅内拉伸测试表明，块状材料钇稳定氧化锆的杨氏模量为 205 GPa，晶格材料的杨氏模量为 83.3 GPa。种植体的最大主应力为61.14兆帕，晶格为278.63兆帕，两者都是可以承受的，这表明重新设计的种植体可以承受每个基台125-250牛顿的咬合力。此外，TO 的质量减少了 13.10%，表面积增加了 208.71%，表明骨结合潜力得到了改善：该研究展示了陶瓷种植体拓扑结构的规划和优化。采用相同的制造工艺和参数，该种植体的进一步迭代已成功植入患者指定的病例中。

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引用次数: 0

Conventionally and digitally fabricated removable complete dentures: manufacturing accuracy, fracture resistance and repairability 传统和数字制作的可摘全口义齿：制造精度、抗断裂性和可修复性。

IF 4.6 1区医学 Q1 DENTISTRY, ORAL SURGERY & MEDICINE

Dental Materials

Pub Date : 2024-07-30 DOI: 10.1016/j.dental.2024.07.022

Objectives

Conventionally and digitally manufactured removable complete dentures with different dentition forms were examined for manufacturing accuracy (trueness, precision), fracture forces under torsional loading and subsequent repairability.

Methods

A total of 90 mandibular prostheses were manufactured. Ten were made using the injection molding technique and finished with prefabricated teeth. 40 bases each, were manufactured subtractively and additively. Digitally the prosthesis’ dental arch was divided either into two quadrants or three sextants, or kept as full arch. Afterwards, ten additive and subtractive bases were finished with prefabricated teeth and ten of each with milled quadrants, sextants and full arches. After manufacturing, all specimens were rescanned for accuracy comparisons using the Root Mean Square (RMS). Lastly, all specimens were tested to failure under torsional loading.

Results

Conventionally manufactured dentures showed the greatest deviation in accuracy. The type of base manufacturing did not determine the fracture resistance of the prostheses. The dentition form had a significant influence. While prefabricated teeth (86.01 ± 19.76 N) and quadrants (77.89 ± 9.58 N) showed a low fracture resistance, sextants (139.12 ± 21.41 N) and full arches (141.05 ± 17.14 N) achieved the highest fracture forces. Subtractive bases with prefabricated teeth or quadrants were assessed to be repairable, digital dentures with full arch were assessed as not repairable.

Significance

The presented testing set-up is suitable to determine the fracture behavior of dentures rather than of standards. With the possibility of digital design and individual manufacturing, dentures’ mechanical stability can be significantly increased, especially with suitable dentition forms.

目的方法：对传统义齿和数字化制造的不同牙列的可摘全口义齿的制造精度（真实度、精确度）、扭转载荷下的断裂力以及随后的可修复性进行研究：共制作了 90 个下颌义齿。方法：共制作了 90 个下颌义齿，其中 10 个采用注射成型技术制作，并用预制牙齿完成。用减法和加法各制作了 40 个基托。修复体的牙弓以数字方式分为两个象限或三个六分仪，或保留为全牙弓。然后，用预制牙齿完成 10 个加法和减法基底，用铣制的象限、六分和全牙弓完成各 10 个基底。制作完成后，对所有试样进行重新扫描，使用均方根（RMS）进行精度比较。最后，所有试样都在扭转载荷下进行了失效测试：结果：传统制造的假牙显示出最大的精度偏差。基托的制造类型并不决定义齿的抗折性。义齿的形式则有很大影响。预制牙（86.01 ± 19.76 N）和四联牙（77.89 ± 9.58 N）的抗折力较低，而六联牙（139.12 ± 21.41 N）和全牙弓（141.05 ± 17.14 N）的抗折力最高。带有预制牙或象限的基托被评估为可修复，带有全牙弓的数字义齿被评估为不可修复：意义：所介绍的测试装置适用于确定假牙的断裂行为，而非标准。随着数字化设计和个性化制造的实现，假牙的机械稳定性可以显著提高，尤其是在合适的牙列形态下。

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引用次数: 0

Biaxial flexural strength of nanoglass and multiwalled carbon nanotubes reinforced 3D-printed denture base resins and their shear bond strength to 3D-printed and acrylic denture teeth 纳米玻璃和多壁碳纳米管增强型三维打印义齿基底树脂的双轴抗弯强度及其与三维打印义齿和丙烯酸义齿的剪切粘接强度。

IF 4.6 1区医学 Q1 DENTISTRY, ORAL SURGERY & MEDICINE

Dental Materials

Pub Date : 2024-07-29 DOI: 10.1016/j.dental.2024.07.026

Objective

Evaluation of biaxial flexural strength (BFS) of nanoglass (NG) and multiwalled carbon nanotubes (MWCNTs) reinforced 3D-printed denture base resins and their shear bond strength (SBS) to 3D-printed and acrylic denture teeth.

Methods

Silanized NG and MWCNTs were added to 3D-printed denture base resin to obtain four groups: Control, 0.25 wt% NG, 0.25 wt% MWCNTs, and a combination group with 0.25 wt% of both fillers. All specimens were tested before and after 600 cycles of thermal aging. BFS (n = 88) was tested using disk-shaped specimens (12 ×2 mm) centralized on an O ring in a universal testing machine. Weibull analysis was conducted to assess predictability of failure. SBS (n = 176) was tested for acrylic and 3D-printed denture teeth attached to bar-shaped specimens in a universal testing machine followed by failure mode analysis using stereomicroscope. Two and three-way ANOVA tests followed by Tukey post hoc test were conducted for BFS and SBS. Kruskal-Wallis test compared percent change among groups with subsequent Dunn post hoc test with Bonferroni correction (α = 0.05).

Results

BFS was affected significantly by filler content (P < 0.001) and thermal cycling (P < 0.001), with thermal cycling displaying the uppermost effect (Ƞp² =0.551). A significant interaction between filler content, thermal cycling, and teeth type was displayed by SBS results (P < 0.001, F=10.340, Ƞp² =0.162). The highest BFS values belonged to 0.25 % MWCNTs while the highest SBS to printed teeth was displayed by the combination.

Significance

The combination group displayed higher BFS and SBS to printed teeth compared to control which allows 3D-printed materials to have a long-term clinical success.

目的：评估纳米玻璃（NG）和多壁碳纳米管（MWCNTs）增强3D打印义齿基底树脂的双轴抗弯强度（BFS）及其与3D打印义齿和丙烯酸义齿的剪切粘结强度（SBS）：将硅烷化 NG 和 MWCNTs 添加到 3D 打印义齿基底树脂中，得到四组：对照组、0.25 wt% NG 组、0.25 wt% MWCNTs 组和含 0.25 wt% 两种填料的组合组。所有试样都在 600 次热老化前后进行了测试。在万能试验机中，使用集中在 O 形环上的圆盘状试样（12 × 2 毫米）对 BFS（n = 88）进行了测试。进行了 Weibull 分析，以评估失效的可预测性。用万能试验机对连接在棒状试样上的丙烯酸义齿和 3D 打印义齿进行 SBS（n = 176）测试，然后用体视显微镜进行失效模式分析。对 BFS 和 SBS 进行了两方和三方方差分析，然后进行 Tukey 后检验。Kruskal-Wallis 检验比较了各组之间的百分比变化，随后进行了 Dunn 后检验，并进行了 Bonferroni 校正（α = 0.05）：结果：BFS 受填料含量的影响很大（P 2 =0.551）。SBS 结果显示，填料含量、热循环和牙型之间存在明显的交互作用（P 2 =0.162）。0.25 % MWCNTs 的 BFS 值最高，而组合组的印齿 SBS 值最高：意义：与对照组相比，组合组打印牙齿的 BFS 和 SBS 值更高，这使得三维打印材料能够获得长期的临床成功。

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引用次数: 0

Monomer elution and shrinkage stress analysis of addition-fragmentation chain-transfer-modified resin composites in relation to the curing protocol 与固化方案有关的加成-断裂链转移改性树脂复合材料的单体洗脱和收缩应力分析。

IF 4.6 1区医学 Q1 DENTISTRY, ORAL SURGERY & MEDICINE

Dental Materials

Pub Date : 2024-07-29 DOI: 10.1016/j.dental.2024.07.029

Objective

The purpose was to compare the effects of rapid (3 s) and conventional (20 s) polymerization protocols (PP) of mono- and multichip LED curing units (LCU) on shrinkage stress (SS) and monomer elution (ME) in bulk-fill resin-based composites (RBC) with and without addition-fragmentation chain-transfer (AFCT) monomer.

Methods

Cylindrical (5x4mm) specimens were prepared from two RBCs containing different AFCT monomers (Filtek OneBulk-FOB; Tetric PowerFill-TPF) and one without (Tetric EvoCeram Bulk-TEC). After soaking for 3, 10, and 14 days (75 % ethanol), ME was quantified using standard monomers by High-Performance Liquid Chromatography. SS was measured from the start of polymerization to 5 min using a Materials Testing Machine. The radiant exitance of LCUs was measured using a spectrophotometer. ANOVA and Tukey's post-hoc test, multivariate analysis and partial eta-squared statistics were used to analyze the data (p < 0.05).

Results

AFCT-modification significantly decreased ME (p < 0.001). ME was reduced by half by day 10 and by one tenth by the end of the 14-day compared to the 3-day sampling. ME itself was dependent, whereas the percentage of monomers released was independent of the PP used (p > 0.05). FOB showed the lowest SS (p < 0.001), while there was no significant difference between TPF and TEC (p = 0.124). Both ME and SS were significantly influenced by material type and PP.

Significance

The incorporation of the AFCT monomer reduced ME, but this was inversely related to a decrease in exposure time. SS values reduced by rapid PP in parallel with increasing ME values. The utilization of the AFCT molecule in conjunction with an appropriate resin-, initiator-system is of significant consequence for the kinetics of polymerization and the incorporation of monomers into the network.

研究目的目的是比较单片和多片 LED 固化单元（LCU）的快速（3 秒）和常规（20 秒）聚合方案（PP）对含和不含加成-断裂链转移（AFCT）单体的块状填充树脂基复合材料（RBC）的收缩应力（SS）和单体洗脱（ME）的影响：用两种含不同 AFCT 单体的 RBC（Filtek OneBulk-FOB；Tetric PowerFill-TPF）和一种不含 AFCT 单体的 RBC（Tetric EvoCeram Bulk-TEC）制备圆柱形（5x4 毫米）试样。浸泡 3 天、10 天和 14 天（75% 乙醇）后，使用标准单体通过高效液相色谱法对 ME 进行量化。使用材料试验机测量了从聚合开始到 5 分钟的 SS 值。使用分光光度计测量 LCU 的辐射出射率。采用方差分析、Tukey 后检验、多元分析和部分等方统计来分析数据（p 结果：AFCT 改性明显降低了 ME（p 0.05）。FOB 显示出最低的 SS（p 显著性：AFCT 单体的加入降低了 ME 值，但这与暴露时间的缩短成反比。随着 ME 值的增加，SS 值也随 PP 值的快速增加而降低。将 AFCT 分子与适当的树脂、引发剂系统结合使用，对聚合动力学和单体融入网络具有重要意义。

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引用次数: 0

Composition control of additively manufactured color-graded temporary veneer 添加剂制造的彩色分级临时单板的成分控制。

IF 4.6 1区医学 Q1 DENTISTRY, ORAL SURGERY & MEDICINE

Dental Materials

Pub Date : 2024-07-29 DOI: 10.1016/j.dental.2024.07.027

Objective

The aim of this study was to design and assess composite resin composition for patient-specific esthetic color-graded temporary veneer.

Methods

Various compositions of composite structures (assorted by Ba₂SiO₄ filler, TiO₂ pigment, and photoinitiator) were prepared via additive manufacturing with 3 s UV exposure (405 nm, 10 W/cm²) per 50 µm thick layer followed by 20 min post-curing treatment after fabrication. The effect of each component on the generated color shades was observed and compared to the commonly used VITA shade guide. The coloration was explored by staining aging treatment under dry, wet, artificial saliva environments, coffee, and cola. The mechanical properties were also evaluated. Color measurement and comparison were done using a colorimeter (lightness (L*), green-red color (a*), and blue-yellow color (b*)), and the changes were calculated by CIEDE2000 (ΔE₀₀), translucency parameter (TP) and whiteness index (WI_D). The composition color analysis results were then applied to produce a color-graded temporary veneer for mimicking a natural look.

Result

Mechanically, all composition result in adequate bending strength with maximum achievable strength of 111.64 MPa. At the same time, the composite color was affected by each constituent differently. The L* value, which indicates the color lightness of the composite, was considerably tuned by the TiO₂ pigment, whereas Ba₂SiO₄ filler only triggered minor changes. Photoinitiator concentration significantly affected the yellowness, indicated by the increased b* value. Similar tendency also observed toward the calculated TP and WI_D as well. Based on these evaluations, color-graded temporary veneer successfully generated, matching the VITA A3, A2, and B1 shades gradation. However, the stability of the composite color decreased at high amounts of Ba₂SiO₄ and photoinitiator.

Significance

The study presents a composition guide for fabricating temporary patient-specific color-graded veneer. It provides insights on the effect of the constituent material on dental esthetics.

目的本研究旨在设计和评估用于患者特定美学色阶临时贴面的复合树脂成分：方法：通过增材制造法制备了各种复合材料结构（由 Ba2SiO4 填料、TiO2 颜料和光引发剂组成），每 50 微米厚的复合材料层经过 3 秒紫外线照射（405 纳米，10 瓦/平方厘米），然后在制造后进行 20 分钟的后固化处理。观察了每种成分对生成色调的影响，并与常用的 VITA 色调指南进行了比较。通过在干燥、潮湿、人工唾液、咖啡和可乐环境下进行染色老化处理，对着色效果进行了研究。此外，还对机械性能进行了评估。颜色的测量和比较使用色度计进行（亮度（L*）、绿-红颜色（a*）和蓝-黄颜色（b*）），其变化由 CIEDE2000（ΔE00）、半透明参数（TP）和白度指数（WID）计算得出。然后将成分颜色分析结果用于生产颜色分级的临时单板，以模仿自然外观：结果：从力学角度看，所有成分都具有足够的抗弯强度，最大可达到 111.64 兆帕。同时，每种成分对复合材料颜色的影响也不同。表示复合材料颜色亮度的 L* 值受 TiO2 颜料的影响较大，而 Ba2SiO4 填料仅引起轻微变化。光引发剂的浓度对黄度的影响很大，b*值的增加表明了这一点。计算得出的 TP 和 WID 也有类似的趋势。根据这些评估结果，成功生成了与 VITA A3、A2 和 B1 色阶相匹配的色阶临时贴面。然而，当 Ba2SiO4 和光引发剂的用量较高时，复合颜色的稳定性下降：这项研究为制作患者专用的临时色阶贴面提供了成分指南。意义：该研究为制作针对特定患者的临时色阶贴面提供了成分指南，并就成分材料对牙齿美学的影响提供了见解。

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引用次数: 0

Load-bearing capacity, internal accuracy and time-efficiency of heat-pressed, milled and 3D-printed lithium disilicate ultra-thin occlusal veneers 热压、铣削和 3D 打印二硅酸锂超薄咬合贴面的承载能力、内部精度和时间效率。

IF 4.6 1区医学 Q1 DENTISTRY, ORAL SURGERY & MEDICINE

Dental Materials

Pub Date : 2024-07-29 DOI: 10.1016/j.dental.2024.07.017

Objectives

The primary aim of this in vitro study was to compare the load-bearing capacity of lithium disilicate occlusal veneers, fabricated via different manufacturing processes. Secondary objectives included assessing internal accuracy and production time-efficiency.

Methods

Four fabrication methods for ultra-thin lithium disilicate occlusal veneers on extracted human molars with simulated erosive defects were compared (n = 20/group): CAM: milled lithium disilicate (IPS e.max CAD); HPR: heat-pressed lithium disilicate (IPS e.max Press) out of a milled PMMA template (Ddpmma CAST); 3DP: 3D-printed lithium disilicate (experimental lithium disilicate); PTE: heat-pressed lithium disilicate (IPS e.max Press) out of a 3D-printed template (SilaPrint cast). Internal accuracy was measured prior to thermo-mechanical aging, followed by static loading to measure the load-bearing capacity (F_max). Fabrication time (time-efficiency) was also recorded. Statistical analysis was performed using the Kruskal-Wallis (KW) test.

Results

No statistically significant differences were found in median load-bearing capacities (F_max) between the groups (KW p = 0.5902): CAM 1821 N, HPR 1896 N, 3DP 2003 N, PTE 1687 N. Significant differences were found in internal accuracy between the groups that employed printing processes (3DP, PTE) and all other groups in margins (p < 0.001), cusps (p < 0.0018), and fossae (p < 0.0346). The time-efficiency measurements indicated an increase in fabrication time, starting from CAM 67.2 ± 5.8 min, followed by HPR 200.8 ± 33.0 min, PTE 289.2 ± 38.7 min, and peaking with the highest duration observed for 3DP 701.6 ± 8.1 min.

Significance

The fabrication method of ultra-thin lithium disilicate occlusal veneers does not significantly impact their load-bearing capacity, but affects the clinical fit and adaptation of the veneers.

研究目的这项体外研究的主要目的是比较通过不同生产工艺制作的二硅酸锂咬合贴面的承重能力。次要目标包括评估内部精度和生产时间效率：比较了四种超薄二硅酸锂咬合贴面的制作方法（n = 20/组）：CAM：铣制二硅酸锂（IPS e.max CAD）；HPR：热压二硅酸锂（IPS e.max Press），采用铣制的 PMMA 模板（Ddpmma CAST）；3DP：3D 打印二硅酸锂（实验二硅酸锂）；PTE：热压二硅酸锂（IPS e.max Press），采用 3D 打印模板（SilaPrint cast）。在热机械老化之前测量内部精度，然后进行静态加载以测量承载能力（Fmax）。同时还记录了制作时间（时间效率）。统计分析采用 Kruskal-Wallis (KW) 检验：结果：各组之间的中位承重能力（Fmax）没有明显的统计学差异（KW p = 0.5902）：采用印刷工艺（3DP、PTE）的组与所有其他组在内部精度方面存在显著差异（p）：超薄二硅酸锂咬合贴面的制作方法不会对其承重能力产生显著影响，但会影响贴面的临床密合性和适应性。

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引用次数: 0

Mitigating lipopolysaccharide-induced impairment in human dental pulp stem cells with tideglusib-doped nanoparticles: Enhancing osteogenic differentiation and mineralization 用掺有tideglusib的纳米颗粒减轻脂多糖诱导的人牙髓干细胞损伤：增强成骨分化和矿化。

IF 4.6 1区医学 Q1 DENTISTRY, ORAL SURGERY & MEDICINE

Dental Materials

Pub Date : 2024-07-26 DOI: 10.1016/j.dental.2024.07.012

Objective

Drug-loaded non-resorbable polymeric nanoparticles (NPs) are proposed as an adjunctive treatment for pulp regenerative strategies. The present in vitro investigation aimed to evaluate the effectiveness of tideglusib-doped nanoparticles (TDg-NPs) in mitigating the adverse effects of bacterial lipopolysaccharide endotoxin (LPS) on the viability, morphology, migration, differentiation and mineralization potential of human dental pulp stem cells (hDPSCs).

Methods

Cell viability, proliferation, and differentiation were assessed using a MTT assay, cell migration evaluation, cell cytoskeleton staining analysis, Alizarin Red S staining and expression of the odontogenic related genes by a real-time quantitative polymerase chain reaction (RT-qPCR) were also performed. Cells were tested both with and without stimulation with LPS at various time points. One-way ANOVA and Tukey's test were employed for statistical analysis (p < 0.05).

Results

Adequate cell viability was encountered in all groups and at every tested time point (24, 48, 72 and 168 h), without differences among the groups (p > 0.05). The analysis of cell cytoskeleton showed nuclear alteration in cultures with undoped NPs after LPS stimulation. These cells exhibited an in blue diffuse and multifocal appearance. Some nuclei looked fragmented and condensed. hDPSCs after LPS stimulation but in the presence of TDg-NPs exhibited less nuclei changes. LPS induced down-regulation of Alkaline phosphatase, Osteonectin and Collagen1 gene markers, after 21d. LPS half-reduced the cells production of calcium deposits in all groups (p < 0.05), except in the group with TDg-NPs (decrease about 10 %).

Significance

LPS induced lower mineral deposition and cytoskeletal disorganization in hDPSCs. These effects were counteracted by TDg-NPs, enhancing osteogenic differentiation and mineralization.

目的：有人提出将药物负载型不可吸收聚合物纳米粒子（NPs）作为牙髓再生策略的辅助治疗手段。本体外研究旨在评估掺杂潮霉素的纳米颗粒（TDg-NPs）在减轻细菌脂多糖内毒素（LPS）对人牙髓干细胞（hDPSCs）的活力、形态、迁移、分化和矿化潜能的不良影响方面的有效性：方法：使用 MTT 试验评估细胞活力、增殖和分化，还进行了细胞迁移评估、细胞骨架染色分析、茜素红 S 染色以及实时定量聚合酶链反应（RT-qPCR）检测牙源性相关基因的表达。在不同的时间点，对细胞进行了有 LPS 刺激和无 LPS 刺激的测试。采用单因素方差分析和 Tukey 检验进行统计分析（p 结果：所有组别在每个测试时间点（24、48、72 和 168 小时）都有足够的细胞活力，组间无差异（p > 0.05）。对细胞细胞骨架的分析表明，在 LPS 刺激后，未掺杂 NPs 的培养物中的细胞核发生了变化。这些细胞呈现蓝色弥漫和多灶外观。经过 LPS 刺激但有 TDg-NPs 存在的 hDPSCs 的细胞核变化较小。21 天后，LPS 诱导碱性磷酸酶、骨连接蛋白和胶原蛋白 1 基因标记下调。LPS 可使各组细胞产生的钙沉积减少一半（p）：LPS 可诱导 hDPSCs 减少矿物质沉积和细胞骨架紊乱。TDg-NPs 可抵消这些影响，促进成骨分化和矿化。

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引用次数: 0

Mechanical properties and crown accuracy of additively manufactured zirconia restorations 快速成型氧化锆修复体的机械性能和牙冠精度。

IF 4.6 1区医学 Q1 DENTISTRY, ORAL SURGERY & MEDICINE

Dental Materials

Pub Date : 2024-07-26 DOI: 10.1016/j.dental.2024.07.016

Objectives

We evaluated the mechanical properties of zirconia restorations produced via additive manufacturing (AM) and the crown accuracy of zirconia crowns.

Methods

Zirconia disks, bars, and crowns were manufactured via subtractive (CNC group) and additive manufacturing (AM group) techniques. Disk-shaped specimens in each group were autoclaved at 134 °C and 216 kPa for 5, 10, and 24 h. The phases of the specimens were analyzed using an X-ray diffractometer. The flexural strengths were measured via biaxial flexural tests. The morphologies were examined using a scanning electron microscope. The correlation between the m-phase fraction and biaxial flexural strength by autoclave time in each group was analyzed via linear mixed model and Pearson’s correlation analysis. For each group, crown specimens were used to assess the marginal and internal gaps using the replica technique. Buccolingual and mesiodistal cross-sections were measured, and a repeated measures one-way ANOVA was performed.

Results

Linear mixed model analysis indicated that for both groups, with an increase in the autoclave time, the flexural strength decreased, whereas the m-phase fraction increased. Pearson’s correlation analysis revealed no correlation between the m-phase fraction and flexural strength for either group. A repeated measures one-way ANOVA was conducted on instrumented sections (buccal, lingual, mesial, and distal), revealing that the marginal and internal gaps of AM-produced zirconia crowns were less accurate than those of CNC-produced zirconia crowns.

Significance

These findings suggest that additively produced zirconia restorations have mechanical properties comparable to those of conventionally produced ceramics and may be suitable for clinical applications.

目的我们评估了通过增材制造（AM）技术生产的氧化锆修复体的机械性能以及氧化锆牙冠的精度：方法：采用减法（CNC 组）和增材制造（AM 组）技术制造氧化锆盘、棒和冠。使用 X 射线衍射仪分析试样的相。弯曲强度通过双轴弯曲试验进行测量。使用扫描电子显微镜检查了形态。通过线性混合模型和皮尔逊相关分析，分析了各组中 m 相组分和双轴抗弯强度与高压釜时间的相关性。使用复制技术对每组牙冠试样的边缘和内部间隙进行评估。测量颊舌侧和牙间侧横截面，并进行重复测量单因素方差分析：线性混合模型分析表明，随着高压灭菌时间的延长，两组牙体的抗折强度都有所下降，而 m 相分数则有所上升。皮尔逊相关分析表明，两组的 m 相分数与抗折强度之间没有相关性。对器械切片（颊侧、舌侧、中侧和远侧）进行了重复测量单因素方差分析，结果显示 AM 生产的氧化锆冠的边缘间隙和内部间隙的精确度低于 CNC 生产的氧化锆冠：这些研究结果表明，添加剂生产的氧化锆修复体的机械性能与传统生产的陶瓷相当，可能适合临床应用。

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引用次数: 0

Enhancing biofilm resistance and preserving optical translucency of 3D printed clear aligners through carboxybetaine-copolymer surface treatment 通过羧基甜菜碱-共聚物表面处理增强三维打印透明对齐器的抗生物膜能力并保持其透光性。

IF 4.6 1区医学 Q1 DENTISTRY, ORAL SURGERY & MEDICINE

Dental Materials

Pub Date : 2024-07-26 DOI: 10.1016/j.dental.2024.07.009

Objectives

This study aimed to use a carboxybetaine methacrylate (CBMA) copolymer solution to surface treat 3D printed clear aligners at different fabrication stages, to impart antifouling properties, and assess the surface treatment at various fabrication stages' impact on physico-mechanical characteristics.

Methods

Surface treatments using a blend of 2-hydroxyethyl methacrylate (HEMA) and CBMA, termed CCS, were performed at various stages of 3D printed clear aligner fabrication. Experimental groups, CB1, CB2, and CB3, were determined by the stage of surface treatment during post-processing. CB1, CB2, and CB3 received treatment before post-curing, after post-curing, and after post-processing, respectively. Untreated samples served as controls. Physical and mechanical properties were assessed through tensile testing, Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and UV-Vis spectroscopy. The surface was further characterized through scanning electron microscopy and contact angle measurements. The cytotoxicity was assessed with 7-day elution and agar diffusion assays. Lastly, bacterial biofilm resistance was evaluated using confocal laser scanning microscopy. Crystal violet assay was performed using Streptococcus mutans.

Results

Surface treatment during CB1 stage exerted the most significantly unfavorable influence on properties of the 3D printed aligner resin. CB2 samples showed the maximum preservation of translucency even after 7-day aging. CB2 and CB3 phases showed enhanced hydrophilicity of sample surfaces with reduced adhesion of multispecies biofilm and S. mutans.

Significance

Application of CCS surface treatment immediately after post-curing (CB2) can enhance the biofilm resistance of 3D printed clear aligners while maintaining high fidelity to optical translucency and constituent mechanical properties.

研究目的：本研究旨在使用甲基丙烯酸羧基甜菜碱（CBMA）共聚物溶液在不同制造阶段对 3D 打印透明对准器进行表面处理，以赋予其防污特性，并评估不同制造阶段的表面处理对物理机械特性的影响：方法：在三维打印透明对齐器制造的不同阶段，使用甲基丙烯酸羟乙酯（HEMA）和 CBMA 的混合物（称为 CCS）进行表面处理。实验组（CB1、CB2 和 CB3）由后处理过程中的表面处理阶段决定。CB1、CB2 和 CB3 分别在后固化前、后固化后和后处理后进行处理。未经处理的样品作为对照组。物理和机械性能通过拉伸测试、傅立叶变换红外光谱（FTIR）、差示扫描量热法（DSC）和紫外可见光谱进行评估。通过扫描电子显微镜和接触角测量进一步确定了表面特征。通过 7 天洗脱和琼脂扩散试验评估了细胞毒性。最后，使用激光共聚焦扫描显微镜评估了细菌的生物膜抗性。使用变异链球菌进行了水晶紫检测：结果：CB1 阶段的表面处理对 3D 打印对准器树脂的性能影响最大。CB2 样品在 7 天老化后仍能最大程度地保持半透明性。CB2 和 CB3 阶段显示，样品表面的亲水性增强，多菌种生物膜和变异杆菌的附着力降低：意义：在后固化（CB2）后立即应用 CCS 表面处理可增强 3D 打印透明对齐器的抗生物膜能力，同时保持高保真的光学半透明度和组成成分的机械性能。

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引用次数: 0

Novel antibacterial orthodontic elastomeric ligature with oral biofilm-regulatory ability to prevent enamel demineralization 具有口腔生物膜调节能力的新型抗菌正畸弹性结扎器，可防止牙釉质脱矿。

IF 4.6 1区医学 Q1 DENTISTRY, ORAL SURGERY & MEDICINE

Dental Materials

Pub Date : 2024-07-26 DOI: 10.1016/j.dental.2024.07.015

Objectives

To synthesize a novel antibacterial orthodontic elastomeric ligature incorporating dimethylaminohexadecyl methacrylate (DMAHDM) for the first time to prevent enamel demineralization during orthodontic therapy.

Methods

Various mass fractions of DMAHDM (ranging from 0 % to 20 %) were grafted onto commercial elastomeric ligatures using an ultraviolet photochemical grafting method and were characterized. The optimal DMAHDM concentration was determined based on biocompatibility and mechanical properties, and the antibacterial efficacy was evaluated in a whole-plaque biofilm model. TaqMan real-time polymerase chain reaction and fluorescence in situ hybridization were used to assess the microbial regulatory ability of the multispecies biofilms. Furthermore, an in vitro tooth demineralization model was established to explore its preventive effects on enamel demineralization. Statistical analysis involved a one-way analysis of variance and LSD post hoc tests at a significance level of 0.05.

Results

The elastomeric ligature containing 2 % mass fraction of DMAHDM exhibited excellent mechanical properties, favorable biocompatibility, and the most effective antibacterial ability against microorganisms, which decreased by almost two logarithms (P < 0.05). It significantly reduced the proportion of Streptococcus mutans in the multispecies plaque biofilm by 25 % at 72 h, leading to an enhanced biofilm microenvironment. Moreover, the novel elastomeric ligature demonstrated an obvious preventive effect on enamel demineralization, with an elastic modulus 30 % higher and hardness 62 % higher than those of the control group within 3 months (P < 0.05).

Significance

The integration of DMAHDM with an elastomeric ligature holds significant promise for regulating biofilms and preventing enamel demineralization in orthodontic applications.

研究目的首次合成一种含有甲基丙烯酸二甲胺基十六烷基酯（DMAHDM）的新型抗菌正畸弹性结扎带，以防止正畸治疗过程中的釉质脱矿：采用紫外线光化学接枝法将不同质量分数的 DMAHDM（从 0% 到 20%）接枝到商用弹性结扎器上，并对其进行了表征。根据生物相容性和机械性能确定了最佳的 DMAHDM 浓度，并在全牙菌斑生物膜模型中评估了其抗菌功效。TaqMan 实时聚合酶链反应和荧光原位杂交被用来评估多菌种生物膜的微生物调控能力。此外，还建立了一个体外牙齿脱矿模型，以探讨其对釉质脱矿的预防作用。统计分析采用单因素方差分析和 LSD 后检验，显著性水平为 0.05：含有 2% 质量分数的 DMAHDM 的弹性结扎器表现出了优异的机械性能、良好的生物相容性和最有效的抗菌能力，对微生物的抗菌能力下降了近两个对数（P 显著性）：在正畸应用中，将 DMAHDM 与弹性结扎器结合在一起，在调节生物膜和防止釉质脱矿方面大有可为。

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引用次数: 0