Thickness

厚度
  • 文章类型: Journal Article
    对于Ni-YSZ阳极支撑的固体氧化物燃料电池(SOFC),主要缺点是由于Ni/NiO体积的变化,它们容易受到还原和氧化气氛的变化。氧化时的阳极膨胀会在电池中引起明显的应力,最终导致失败。为了提高氧化还原稳定性,建立了分析模型来研究阳极结构对氧化还原稳定性的影响。与没有AFL的SOFC相比,阳极氧化后,具有阳极功能层(AFL)的SOFC的电解质和阴极中的拉伸应力分别增加了27.07%和20.77%,分别。阳极结构的厚度对结构的稳定性有很大影响。因此,还讨论了阳极厚度和AFL厚度对氧化后这两种结构中应力的影响。阳极基板的厚度在没有AFL的SOFC中比在具有AFL的SOFC中起到更重要的作用。通过增加阳极基板的厚度,电解质和阴极中的应力降低。该方法为在氧化还原条件下设计可靠的SOFC提供了理论依据,并将在将来有更多的实验证明。
    For Ni-YSZ anode-supported solid oxide fuel cells (SOFCs), the main drawback is that they are susceptible to reducing and oxidizing atmosphere changes because of the Ni/NiO volume variation. The anode expansion upon oxidation can cause significant stresses in the cell, eventually leading to failure. In order to improve the redox stability, an analytical model is developed to study the effect of anode structure on redox stability. Compared with the SOFC without AFL, the tensile stresses in the electrolyte and cathode of SOFC with an anode functional layer (AFL) after anode oxidation are increased by 27.07% and 20.77%, respectively. The thickness of the anode structure has a great influence on the structure\'s stability. Therefore, the influence of anode thickness and AFL thickness on the stress in these two structures after oxidation is also discussed. The thickness of the anode substrate plays a more important role in the SOFC without AFL than in the SOFC with AFL. By increasing the thickness of the anode substrate, the stresses in the electrolyte and cathode decrease. This method provides a theoretical basis for the design of a reliable SOFC in the redox condition and will be more reliable with more experimental proofs in the future.
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  • 文章类型: Journal Article
    目的:评估狗患有不同疾病的胆囊壁各层的厚度。
    方法:72个胆囊。
    方法:对接受胆囊切除术的狗进行回顾性研究。回顾了胆囊的组织病理学标本。组织病理学诊断为胆囊黏液囊肿或胆囊炎,胆囊炎被进一步归类为慢性胆囊炎,急性对慢性胆囊炎,急性胆囊炎,和坏死性胆囊炎.测量胆囊壁各层的厚度。
    结果:22只狗被诊断为胆囊黏液囊肿而无胆囊炎,24伴有胆囊黏液囊肿和胆囊炎,20只患有胆囊炎,6和正常一样。44例胆囊胆囊炎的组织病理学分类导致21例胆囊慢性胆囊炎的诊断,10个胆囊急性对慢性胆囊炎,急性胆囊炎在6个胆囊,和7个胆囊坏死性胆囊炎。胆囊全壁厚度(P<.0001)、黏膜厚度(P<.0001)和浆膜下厚度(P<.0001)受不同疾病进程的影响。
    结论:胆囊壁层受胆囊疾病的影响。在这项研究中,这导致了胆囊疾病之间胆囊壁厚度的差异。手术前应考虑组织病理学变化,同时决定使用哪种技术进行胆囊切除术。
    OBJECTIVE: To assess the thickness of each layer of the gallbladder wall with different diseases in dogs.
    METHODS: 72 gallbladders.
    METHODS: Retrospective study of dogs that underwent cholecystectomy. Histopathological specimens of the gallbladders were reviewed. Histopathological diagnosis was made as gallbladder mucocele or cholecystitis, and cholecystitis was further categorized into chronic cholecystitis, acute-on-chronic cholecystitis, acute cholecystitis, and necrotic cholecystitis. The thickness of each layer of the gallbladder wall was measured.
    RESULTS: 22 dogs were diagnosed with gallbladder mucocele without cholecystitis, 24 with gallbladder mucocele and cholecystitis, 20 with only cholecystitis, and 6 as normal. Histopathological subclassification of cholecystitis in 44 gallbladders led to diagnosis of chronic cholecystitis in 21 gallbladders, acute-on-chronic cholecystitis in 10 gallbladders, acute cholecystitis in 6 gallbladders, and necrotic cholecystitis in 7 gallbladders. The thickness of the entire wall of the gallbladder (P < .0001) and the thickness of the mucosa (P < .0001) and subserosa (P < .0001) were affected by the different disease processes.
    CONCLUSIONS: Layers of the gallbladder wall were affected by diseases present in the gallbladder. It resulted in a difference in the thickness of the wall of the gallbladder among the gallbladder diseases in this study. Histopathological changes should be taken into consideration before surgery while deciding what technique to use to perform a cholecystectomy.
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  • 文章类型: Journal Article
    这项研究的目的是研究使用清晰的矫正器在上颌弓扩张过程中不同的牙齿移动方式和矫正器厚度对牙齿和牙周组织的生物力学影响,以促进更精确和有效的临床正畸治疗。
    包括牙齿的三维模型,上颌骨,牙周膜,和对准器进行了构造和有限元分析。测量了7种牙齿位移模式的牙齿位移趋势和牙周膜应力(分为三类,包括前磨牙和磨牙的整体运动,每个步骤中磨牙的扩张逐渐增加;前磨牙和磨牙的分布运动;以及前磨牙和磨牙之间间隔交替运动)和两个矫正器厚度(0.5mm和0.75mm)。
    用清晰的矫正器扩张上颌弓时,目标牙齿的有效扩张主要表现为倾斜运动趋势。增加磨牙膨胀的量增加了第一磨牙的颊位移,但减少了前磨牙的颊位移。后牙间隔交替运动组(0.026mm)的目标牙齿平均颊位移大于前磨牙/磨牙分布运动组(0.016mm)和整体运动组(0.015mm)。矫正器厚度的增加会导致牙冠的口腔位移更大,并增加牙周韧带的应力。
    增加摩尔膨胀的量会降低前摩尔膨胀的效率。前磨牙和磨牙间隔交替运动可实现更高的牙弓扩张效率,但应注意相邻牙齿的锚固。增加矫正器的厚度会增加膨胀效率,但也会增加牙周组织的负担。
    UNASSIGNED: The objective of this study was to investigate the biomechanical effects of different tooth movement patterns and aligner thicknesses on teeth and periodontal tissues during maxillary arch expansion with clear aligners, to facilitate more precise and efficient clinical orthodontic treatments.
    UNASSIGNED: Three-dimensional models including teeth, maxilla, periodontal ligament, and aligner were constructed and subjected to finite element analysis. Tooth displacement trends and periodontal ligament stresses were measured for seven tooth displacement patterns (divided into three categories including overall movement of premolars and molars with gradually increasing molar expansion in each step; distributed movement of premolars and molars; and alternating movement between premolars and molars at intervals) and two aligner thicknesses (0.5 mm and 0.75 mm) during maxillary arch expansion with clear aligners.
    UNASSIGNED: When expanding the maxillary arch with clear aligners, the effective expansion of the target teeth mainly showed a tilting movement trend. Increasing the amount of molar expansion increased the buccal displacement of the first molar but decreased the buccal displacement of the premolars. The mean buccal displacement of the target teeth was greater in the posterior teeth interval alternating movement group (0.026 mm) than in the premolar/molar distributed movement group (0.016 mm) and the overall movement group (0.015 mm). Increasing aligner thickness resulted in greater buccal displacement of the crowns and increased stress on the periodontal ligaments.
    UNASSIGNED: Increasing the amount of molar expansion reduces the efficiency of premolar expansion. Alternating movement of premolars and molars at intervals achieves a higher arch expansion efficiency, but attention should be paid to the anchorage of adjacent teeth. Increasing the thickness of the aligner increases the expansion efficiency but may also increase the burden on the periodontal tissues.
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  • 文章类型: Journal Article
    目的:牙龈表型(GP)被认为是预测正畸治疗获得良好美学和功能结果的可能性的有价值的指标。这项研究旨在研究锥形束计算机断层扫描(CBCT)的准确性和可重复性,以评估与跨牙龈探查方法相比的两个牙弓的牙龈厚度(GT)。次要目标是使用CBCT确定GT的最佳截止值。
    方法:进行了这项横断面研究,其中GP是基于探针透明度方法(TRAN)确定的。对于第一磨牙前的所有牙齿,GT测量均通过两种方法在距游离牙龈边缘(FGM)2mm处获得。数据采用组内相关系数(ICC)进行统计分析,Bland-Altman阴谋,和接收器工作特性(ROC)曲线。统计学显著性水平设定为P值<0.05。
    结果:该研究包括60名受试者(1200颗牙齿)。上颌(1.14±0.17mm)和下颌(0.94±0.15mm)牙弓的平均GT明显高于CBCT方法(P<0.05)。如Bland-Altman情节所示,两种方法之间的偏倚在上颌(0.060;95%CI:0.044~0.076)和GP厚个体(0.096;95%CI:0.082~0.109)中较大.GT测量的最佳值为上颌1.15mm,下颌1.02mm,男性为1.02mm,女性为1.09毫米。
    结论:CBCT在诊断GT方面表现出显著的准确性,虽然与传统的跨牙龈探查技术相比差异最小,在薄薄的全科医生中尤其明显,在下颌牙弓。在上颌弓和GP较厚的病例中观察到与CBCT使用相关的限制。
    OBJECTIVE: Gingival phenotype (GP) is regarded as a valuable indicator for forecasting the probability of attaining favourable aesthetic and functional results with orthodontic treatment. This study aimed to investigate the accuracy and reproducibility of cone beam computed tomography (CBCT) for assessing gingival thickness (GT) in both arches compared to the transgingival probing method. The secondary objective was to determine the optimal cut-off values for GT using CBCT.
    METHODS: This cross-sectional study was conducted where GP was determined based on the probe transparency method (TRAN). The GT measurements were obtained by both methods at 2mm from the free gingival margin (FGM) for all teeth anterior to the first molar. The data was statistically analysed using intraclass correlation coefficient (ICC), Bland-Altman plots, and receiver operating characteristic (ROC) curves. The statistical significance level was set at a P-value<0.05.
    RESULTS: The study included 60 subjects (1200 teeth). The mean GT in both the maxillary (1.14±0.17mm) and mandibular (0.94±0.15mm) arches was significantly greater (P<0.05) for the transgingival probing method than for the CBCT method. As shown in the Bland-Altman plot, the bias between the two methods was greater in the maxillary jaw (0.060; 95% CI: 0.044 to 0.076) and in individuals with a thick GP (0.096; 95% CI: 0.082 to 0.109). The optimal values for GT measurements were 1.15mm for the maxillary jaw, 1.02mm for the mandibular jaw, 1.02mm for males, and 1.09mm for females.
    CONCLUSIONS: CBCT exhibited notable precision in diagnosing GT, while demonstrating minimal disparities compared to the conventional transgingival probing technique, particularly evident in thin GPs, and in the mandibular dental arch. The constraints associated with the utilization of CBCT were observed in the maxillary arch and in cases with thick GP.
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  • 文章类型: Journal Article
    背景:先前基于人群的研究报道,大多数黑色素瘤死亡率与薄型(≤1mmBreslow厚度)黑色素瘤患者有关。本研究的目的是评估在过去20年中在美国诊断的黑色素瘤的所有阶段中黑色素瘤特异性死亡的相对比例。
    方法:对美国监测中所有皮肤黑色素瘤病例的回顾,流行病学,并进行了2004年至2020年的最终结果登记。Breslow厚度被归类为薄(≤1.0毫米),中间(>1-4毫米),或厚(>4毫米)。在诊断时,比较了肿瘤厚度和阶段组的全因死亡和黑色素瘤特异性死亡。对被认为是竞争风险的非黑色素瘤死亡进行生存分析,以估计黑色素瘤特异性死亡的累积发生率。
    结果:大多数黑色素瘤死亡发生在最初出现局部疾病(53%)的患者中,与局部疾病(36%)或远处疾病(11%)相比(P<0.001)。然而,出现局部疾病的患者中,大多数(66%)的黑色素瘤特异性死亡是中度或重度(即,Breslow厚度>1.0mm)原发性肿瘤与薄黑色素瘤(34%)相比。诊断时,局部薄型黑色素瘤患者在10年时黑色素瘤特异性死亡的累积发生率为2.6%(95%置信区间为2.5%-2.7%)。
    结论:就黑色素瘤特异性死亡率而言,公共卫生负担与肿瘤厚度>1mmBreslow患者有关,其中许多人在诊断时患有区域性和远处转移性疾病,不是薄薄的黑色素瘤患者。
    BACKGROUND: Previous population-based studies have reported that the majority of melanoma mortality is related to patients with thin (≤1 mm Breslow thickness) melanomas. The aim of the present study was to evaluate the relative proportion of melanoma-specific deaths across all stages of melanoma at diagnosis over the past 20 y in the United States.
    METHODS: A review of all cutaneous melanoma cases in the US Surveillance, Epidemiology, and End Results registry from 2004 to 2020 was performed. Breslow thickness was categorized as thin (≤1.0 mm), intermediate (>1-4 mm), or thick (>4 mm). All-cause deaths and melanoma-specific deaths were compared across tumor thickness and stage groups at diagnosis. Survival analysis was performed with nonmelanoma deaths considered as a competing risk to estimate the cumulative incidence of melanoma-specific death.
    RESULTS: Most melanoma deaths occurred in patients who initially presented with local disease (53%) compared to regional (36%) or distant (11%) disease (P < 0.001). However, most (66%) of the melanoma-specific deaths in patients who presented with localized disease were in those with intermediate or thick (i.e., Breslow thickness >1.0 mm) primary tumors compared to those with thin melanomas (34%). The cumulative incidence of melanoma-specific death at 10 y in patients with localized thin melanomas at the time of diagnosis was 2.6% (95% confidence intervals 2.5%-2.7%).
    CONCLUSIONS: The public health burden in terms of melanoma-specific mortality is related to patients with tumors >1 mm Breslow thickness, many of whom have regional and distant metastatic disease at the time of diagnosis, not patients with thin melanomas.
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  • 文章类型: Journal Article
    背景:牙龈生物型(GB)影响几个牙科专业的治疗计划和临床结果。本研究旨在探讨GB与各种临床牙冠和牙周参数之间的关系,例如探测深度(PD),乳头高度(PH),角化组织宽度(KTW),冠宽/冠长比(CW/CL),和牙龈厚度(GT)。次要目标是评估所有参数的最佳临界值,以确定上颌和下颌前牙的GB。
    方法:这项横断面研究包括50名年龄在20至35岁之间的健康个体(26名男性和24名女性)。根据牙周探针通过口腔牙龈边缘(TRAN)的透明度,将GB确定为二元变量。临床牙冠和牙周参数,如PH,PD,KTW,GT(游离牙龈厚度[FGT]和附着牙龈厚度[AGT]),测量CW/CL比。通过卡方检验评估不同变量之间的关联。使用点双材料相关性分析评估了各种临床参数与GB之间的相关性。接收器工作特性(ROC)分析和Youden指数用于计算pH值的最佳截止值,PD,KTW,FGT,AGT,和CW/CL比率来区分GB。统计学显著性水平设定为p<0.05。
    结果:男性的平均年龄为28.23±2.81岁,而女性为27.08±2.85岁。56%的人中存在厚GB,和薄的GB存在于44%的个体。与女性相比,与女性相比,男性倾向于厚厚的GB。根据ROC分析,区分下颌前牙GB的临界值为PH为3.4mm,1.96毫米的PD,4.21毫米,适用于KTW,FGT为0.98mm,AGT为0.43毫米,CW/CL比率为0.91。同样,区分上颌前牙的GB的临界值为PH为4.02mm,1.92毫米的PD,KTW为3.89mm,FGT为1.02mm,AGT为0.42mm,CW/CL比率为0.83。PH,PD,FGT与GB呈较强的正相关,而KTW,AGT,CW/CL比值与GB呈弱正相关。
    结论:在本研究的局限性内,已证实所有临床牙冠和牙周参数与GB之间存在显着关联。基于ROC分析,下颌前牙的FGT和下颌前牙的PH已成为区分厚GB和薄GB的最可靠测量。
    结论:所有临床参数,如乳头高度,探测深度,角化牙龈的宽度,牙龈厚度,冠宽/高比与牙龈生物型显著相关。下颌前牙的游离牙龈厚度和上颌前牙的乳头高度已成为区分厚牙龈生物型和薄牙龈生物型的最可靠指标。
    BACKGROUND: The gingival biotype (GB) influences treatment planning and clinical outcomes in several dental specialties. This study aimed to investigate the associations between the GB and various clinical crown and periodontal parameters, such as probing depth (PD), papillary height (PH), keratinized tissue width (KTW), crown width/crown length ratio (CW/CL), and gingival thickness (GT). The secondary objective was to evaluate the optimal cutoff values for all parameters to determine the GB in both the maxillary and mandibular anterior teeth.
    METHODS: This cross-sectional study included 50 healthy individuals (26 men and 24 women) aged between 20 and 35 years. The GB was determined as a binary variable based on the transparency of a periodontal probe through the buccal gingival margin (TRAN). The clinical crown and periodontal parameters, such as PH, PD, KTW, GT (free gingival thickness [FGT] and attached gingival thickness [AGT]), and the CW/CL ratio were measured. The associations between different variables were evaluated by the chi-square test. Correlations between various clinical parameters and GB were assessed using point-biserial correlation analyses. Receiver operating characteristic (ROC) analysis and the Youden index were used to calculate the optimal cutoff values for the PH, PD, KTW, FGT, AGT, and CW/CL ratio to discriminate GB. The statistical significance level was set at p < 0.05.
    RESULTS: The mean age of the males was 28.23 ± 2.81 years, while that of the females was 27.08 ± 2.85 years. Thick GB was present in 56% of individuals, and thin GB was present in 44% of individuals. Compared with females, males had a predilection for thick GB compared with females. According to the ROC analysis, the cutoff values to discriminate GB for mandibular anterior teeth were 3.4 mm for PH, 1.96 mm for PD, 4.21 mm for KTW, 0.98 mm for FGT, 0.43 mm for AGT, and 0.91 for the CW/CL ratio. Similarly, the cutoff values for discriminating the GB for maxillary anterior teeth were 4.02 mm for PH, 1.92 mm for PD, 3.89 mm for KTW, 1.02 mm for FGT, 0.42 mm for AGT, and 0.83 for the CW/CL ratio. PH, PD, and FGT showed strong positive correlations with GB, whereas KTW, AGT, and the CW/CL ratio showed weak positive correlation with GB.
    CONCLUSIONS: Within the limitations of the present study, a significant association between all clinical crown and periodontal parameters with the GB has been confirmed. FGT for mandibular anterior teeth and PH for the mandibular anterior teeth have emerged as the most reliable measurements to differentiate between thick and thin GB based on ROC analysis.
    CONCLUSIONS: All the clinical parameters such as papillary height, probing depth, width of keratinized gingiva, gingival thickness, and crown width/height ratio were significantly associated with gingival biotype. Free gingival thickness for mandibular anterior teeth and papillary height for the maxillary anterior teeth have emerged as the most reliable measurement to differentiate between thick and thin gingival biotypes.
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  • 文章类型: Journal Article
    背景:Chin假体植入,矫正下巴不对称的整容手术,抑郁症,或撤回,通常是安全和简单的。然而,它对周围组织的长期影响令人担忧。本研究旨在使用三维(3D)扫描来对下颌肌肉的形状进行分类,并评估假体植入对这些肌肉的影响。
    方法:本研究评估了450名符合条件的女性参与者。使用三维成像,类型上的数据,厚度,宽度,收集并总结了左、右下颌肌的长度。使用方差分析评估了下巴假体对这些肌肉尺寸的影响,对肌肉类型的影响采用χ2检验。
    结果:Chin植入物的放置影响了mentalis肌肉,导致长度增加,厚度,和宽度。受试者的精神肌分为3种类型,分为7种亚型。χ2检验结果表明,植入会影响这些肌肉的分类。
    结论:认识到植入物放置如何影响下颌肌可以指导治疗的发展,以减轻这些变化。此外,了解肌肉的形态可以为患者提供更精确的治疗方法。
    BACKGROUND: Chin prosthesis implantation, a cosmetic procedure to correct chin asymmetry, depression, or retraction, is generally safe and simple. However, its long-term effects on surrounding tissues are a concern. This study aimed to use three-dimensional (3D) scanning to classify the mentalis muscle shapes and assess the impact of prosthesis implantation on these muscles.
    METHODS: This study evaluated 450 eligible female participants. Using three-dimensional imaging, data on the types, thickness, width, and length of the left and right mentalis muscles were collected and summarized. The impact of chin prosthesis on these muscle dimensions was assessed using analysis of variance, and the effect on muscle type was determined using χ2 test.
    RESULTS: Chin implant placement affected the mentalis muscles, resulting in increased length, thickness, and width. The subjects\' mentalis muscles were categorized into 3 types and divided into 7 subtypes. χ2 test results indicated that implantation influences the classification of these muscles.
    CONCLUSIONS: Recognizing how implant placement affects the mentalis muscle can guide the development of treatments to mitigate these changes. Additionally, understanding the muscle\'s morphology enables more precise treatment approaches for patients.
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  • 文章类型: Journal Article
    HfO2基铁电材料是最有希望的铁电存储器候选材料,由于其优异的铁电性能和CMOS兼容性,已被广泛研究了十多年。为了尽快实现其产业化,研究人员一直致力于提高可靠性性能,比如醒来,印记,有限的耐力,etal.其中,击穿特性是HfO2基铁电体器件的主要失效机理之一,这限制了设备的写/读可靠性。基于此,在正向和反向电应力条件下,我们系统地研究了厚度对HfO2-ZrO2(HZO)FE薄膜的时间依赖性介电击穿(TDDB)耐受能力的影响。HZOFE薄膜的厚度范围为6nm至20nm。我们的发现表明,降低HZOFE薄膜的厚度会导致TDDB耐受能力的提高,这归因于较薄的HZOFE薄膜中较高的氧空位密度可以有效抑制新的氧空位的产生和导电丝的生长。从而有效地改善了TDDB的特性。这些结果为减轻存储器应用中基于HfO2的铁电装置的击穿特性提供了潜在的解决方案。 .
    HfO2-based ferroelectric materials as the most promising candidate for the ferroelectric memories, have been widely studied for more than a decade due to their excellent ferroelectric properties and CMOS compatibility. In order to realize its industrialization as soon as possible, researchers have been devoted to improving the reliability performance, such as wake up, imprint, limited endurance, et al. Among them, the breakdown characteristic is one of main failure mechanisms of HfO2-based ferroelectric devices, which limits the write/read reliability of the devices. Based on this, we systematically studied the effect of thickness on the time-dependent dielectric breakdown (TDDB) tolerate capability of HfO2-ZrO2(HZO) FE films under both forward and reverse electrical stress conditions. The thickness of HZO FE film ranged from 6 to 20 nm. Our findings reveal that decreasing the thickness of the HZO FE film leads to an improvement in TDDB tolerance capability which is attributed to the fact that higher density of oxygen vacancies in thinner HZO FE films can effectively inhibit the generation of new oxygen vacancies and the growth of conductive filaments, thus effectively improving the TDDB characteristics. These results provide a potential solution for mitigating breakdown characteristics of HfO2-based ferroelectric devices in memory applications.
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  • 文章类型: Journal Article
    背景:比较和研究口腔内老化对一组直接打印和两组热成型对准器在上颌中切牙唇表面厚度的影响。
    方法:该前瞻性体内实验包括6组(每组12个样品)。组DP-Clin,INV-Clin和CA-Clin由直接印刷(TeraHarzTC-85DAC树脂)组成,热成型(Invisalign,PU基聚合物)和室内热成型(CA-Pro,PET-G基聚合物)矫正器,在口腔内服务1周后检索。组DP-Ctr,INV-Ctr和CA-Ctr包括未使用的对准器样品。使用共聚焦激光扫描显微镜(CLSM)进行厚度测量。通过多元线性回归分析(p<.05)分析经过log-10转化的数据。
    结果:在Clin和Ctr类别的材料之间发现了统计学上的显着差异(p<.001)。DP组在各组中具有最高的厚度,并且在CA组中观察到最小的厚度(p〈.001)。然而,口内老化对任何组的矫正器厚度均无显著影响.
    结论:透明矫正器的热成型和直接印刷均导致厚度偏差,即印刷矫正器的厚度增加和热成型矫正器的厚度减少。口腔内老化不影响任何组中的矫正器厚度。
    BACKGROUND: To compare and investigate the effects of intraoral ageing on the thickness of one group of directly printed and two groups of thermoformed aligners on the labial surface of maxillary central incisors.
    METHODS: Six groups (12 samples per group) were included in this prospective in vivo experiment. Groups DP-Clin, INV-Clin and CA-Clin consisted of directly printed (Tera Harz TC-85 DAC resin), thermoformed (Invisalign, PU based polymer) and in house thermoformed (CA-Pro, PET-G based polymer) aligners, retrieved after 1 week of intraoral service. Groups DP-Ctr, INV-Ctr and CA-Ctr included unused aligners samples. Thickness measurements were conducted using confocal laser scanning microscopy (CLSM). Data that underwent log-10 transformation was analysed by multiple linear regression analysis (p < .05).
    RESULTS: Statistically significant differences were found between the materials in both Clin and Ctr categories (p < .001). Group DP had the highest thickness among the groups and the least thickness was observed in the CA group (p < .001). However, intraoral ageing did not significantly affect the aligner thickness of any groups.
    CONCLUSIONS: Both thermoforming and direct printing of clear aligners led to thickness deviations in terms of increase for printed aligners and decrease for thermoformed aligners. Intraoral ageing did not affect the aligner thickness in any of the groups.
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  • 文章类型: Journal Article
    背景:陶瓷半透明的影响,层厚度,在一些研究中,二硅酸锂玻璃陶瓷修复体的阴影和基底颜色被证明是重要的,然而,定量,关于色差与这些参数之间关系的数值结果仍然缺乏。这项体外研究的目的是定量确定二硅酸锂玻璃陶瓷的颜色再现能力如何受到其半透明性的影响。层厚度,和基材颜色。
    方法:陶瓷样品由具有高和低半透明性(HT和LT)的A2色调IPSE.maxCAD块在0.5-2.5mm(+/-0.05mm)的厚度范围内制备。利用9种色调的复合基材获得分层样品;使用透明试吃膏。在D65标准照明下用柯尼卡美能达CM-3720d分光光度计评估样品的光谱反射率。使用设定为50:50%的可感知性和可接受性阈值分析了两个样品之间的TheCIEDE2000色差(ΔE00)。统计分析包括线性回归分析和Kruskal-Wallis检验。
    结果:厚度增加0.5mm时,HT样品的ΔE00降低到72.8%,T样品的比例为71.1%(p<0.0001)。具有HT和LT样品的7种底物具有与平均值显著不同的结果(p<0.05)。0.5mm的厚度不足以在任何半透明水平下实现可接受的结果,而厚度为1.5毫米的低半透明陶瓷给出了可接受的结果,除了严重变色的底物(ND8和ND9)。
    结论:二硅酸锂微晶玻璃的颜色再现能力受半透明性的显著影响,层厚度,和检查的9个衬底中的7个衬底。
    BACKGROUND: Effects of ceramic translucency, layer thickness, and substrate colour on the shade of lithium disilicate glass-ceramic restorations proved to be significant in several studies, however, quantitative, numerical results on the relationship between the colour difference and these parameters are still lacking. The purpose of this in vitro study was to quantitatively determine how the colour reproduction ability of a lithium disilicate glass-ceramic is affected by its translucency, layer thickness, and substrate colour.
    METHODS: Ceramic samples were prepared from A2 shade IPS e.max CAD blocks with high and low translucencies (HT and LT) in a thickness range of 0.5-2.5 mm (+/- 0.05 mm). Layered samples were acquired utilizing composite substrates in 9 shades; transparent try-in paste was used. The spectral reflectance of the specimens was assessed under D65 standard illumination with a Konica Minolta CM-3720d spectrophotometer. The CIEDE2000 colour difference (ΔE00) between two samples was analysed using perceptibility and acceptability thresholds set at 50:50%. Statistical analysis involved linear regression analysis and the Kruskal-Wallis test.
    RESULTS: An increase in the thickness of 0.5 mm reduced the ΔE00 of the HT samples to 72.8%, and that of the T samples to 71.1% (p < 0.0001). 7 substrates with HT and LT specimens had significantly different results from the mean (p < 0.05). A thickness of 0.5 mm is not sufficient to achieve an acceptable result at any level of translucency, while the low translucency ceramic at a thickness of 1.5 mm gave acceptable results, except for severely discoloured substrates (ND8 and ND9).
    CONCLUSIONS: The colour reproduction ability of lithium disilicate glass-ceramics is significantly affected by their translucency, layer thickness, and 7 substrates out of 9 substrates examined.
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