A New Technology of Microcrystallizing Leucite to Reinforce Dental Glass Ceramics

The key technology and the main mechanism of microcrystallizing leucite to reinforce dental glass ceramics were investigated.The feedstock powders were selected,mixed according to the ratios of the theoretical composition of leucite,ball-milled,melted at 1600℃ and then cooled to room temperature quickly.The cooled clinkers were ball-milled again to 4 μm.After cold-isostatic pressure molded and air sintered at 1500℃ for 1 h,the dental glass ceramics were fabricated.They have following characteristics:excellent mechanical properties (mean compressive strength is 206.6 MPa),low sintering temperature and good reoccurrence to keep steady quality.

Shear bond strengths between alumina-toughened zirconia cores and veneering ceramics and their susceptibility to aging

Objective:To evaluate the shear bond strength(SBS) between alumina-toughened zirconia (ATZ) cores and veneering ceramics,investigate the effect of aging in artificial saliva on SBS and compare it with that of yttria-stabilized tetragonal zirconia polycrystals(Y-TZP).Methods:Bars of ATZ and Y-TZP were layered with veneering ceramics in accordance to the recommendation of the manufacturer.Half of each group(n = 10) was aged at 134℃.(under 2 bar pressure) in an autoclave for 48 h.Subsequently,all specimens were subjected to shear force in a universal testing machine.The interface and fractured surface of the specimens were evaluated using scanning electron microscopy and X-ray energy dispersive spectroscopy.Results:The initial mean SBS values in MPa±SD were 28.9±8.0 for ATZ and 26.2±7.6 for Y-TZP.After aging,the mean SBS values for ATZ and Y-TZP were 22.9±4.9 MPa and 22.8±6.9 MPa,respectively.Neither the differences between the SBS values of the ATZ and Y-TZP groups nor the influence of aging on all groups were statistically significant.Conclusions:The SBS between the ATZ core and the veneering ceramics was not affected by aging.The SBS of ATZ to veneering ceramics was not significantly different compared with that of Y-TZP.

Optimized sintering and mechanical properties of Y-TZP ceramics for dental restorations by adding lithium disilicate glass ceramics

The novel dental ceramics can be fabricated at lower temperatures when sol-gel derived lithium disilicate glass ceramics(LDGC)was used as an additive for yttria stabilized tetragonal zirconia polycrystalline(Y-TZP)ceramics.The effect of LDGC on the sintering,mechanical,and translucent properties of Y-TZP ceramics was investigated in the present study.The results showed that the LDGC additive effectively improved the densification of Y-TZP at 1100℃,which was much lower than the sintering temperature for pure Y-TZP.When sintered at 1100℃,the Y-TZP with 1 wt%LDGC reached a relative density of 95.45%,and prossessed a flexural strength of 482.4 MPa and a fracture toughness of 5.94 MPa-m12.Moreover,its translucency was also improved.While,the addition of LDGC could result in an escape of yttrium atoms from the grain lattice of zirconia,which induced the tetragonal-monoclinic transformation of zirconia and abnormal growth of monoclinic grains.The escaped yttrium atoms diffused into the intergranular glass phase.The results indicated that the novel Y-TZP-LDGC ceramics has a great potential to be used for all-ceramic restorations.

Comparative study of flexural strength test methods on CAD/CAM Y-TZP dental ceramics

Clinically,fractures are the main cause of computer-aided design and computer-aided manufacturing(CAD/CAM)3 mol%-yttria-stabilized tetragonal zirconia polycrystal(Y-TZP)all-ceramic dental restorations failure because of repetitive occlusal loading.The goal of this work is to study the effect of test methods and specimen’s size on the flexural strength of five ceramic products.Both biaxial flexure test(BI)and uni-axial flexure tests(UNI),including three-point flexure test(3PF)and four-point flexure test(4PF),are used in this study.For all five products,the flexural strength is as follows:BI>3PF>4PF.Furthermore,specimens with smaller size(3PF-s)have higher values than the bigger ones(3PF).The difference between BI and UNI resulted from the edge flaws in ceramic specimens.The relationship between different UNI(including 3PF-s,3PF and 4PF)can be explained according to Weibull statistical fracture theory.BI is recommended to evaluate the flexural strength of CAD/CAM Y-TZP dental ceramics.

牙科树脂渗透陶瓷复合材料制备的研究进展

树脂渗透陶瓷(PICN)复合材料是一种由树脂和陶瓷2种互穿网状相构成的新型牙科修复材料,具有优良的天然牙仿生性能和易加工性,特别适用于基于椅旁计算机辅助设计和制造技术的快速牙体缺失和缺损的修复,正逐渐成为研究和应用的热点。PICN的力学性能和美学性能等可通过成分设计、优化制备工艺和表面改性等来调控。本文综述了PICN材料制备的研究进展,详述了多孔陶瓷制备、树脂渗透和固化工艺等方面研究现状,展望了未来发展趋势和研究重点。

Ceramic Laminate Veneers: Materials Advances and Selection

Porcelain laminate veneers have been a common treatment strategy in dental clinics. It is a conservative method for treatment of esthetic and functional problems in anterior region of oral cavity. Wide range of dental ceramics is now available on market for fabrication of laminate veneers. Clinician should have enough knowledge regarding the composition and properties of these materials in order to be able to choose the appropriate one according to clinical situations.

Biocompatibility of biphasic α,β-tricalcium phosphate ceramics in vitro

The biocompatibility of biphasicα,β-tricalcium phosphate ceramics,obtained by annealing a compact preform based onβ-tricalcium phosphate powder,was studied in vitro.It was found that within 10–30 days the adhesion of primary dental pulp stem cells located on the surface of biphasicα,β-tricalcium phosphate ceramics is suppressed.Decrease of the cell number on the surface of biphasicα,β-tricalcium phosphate ceramics,most likely,can be associated with both the pH level(acidic)as a result of hydrolysis of the more soluble phase ofα-tricalcium phosphate and with the nature of surface that changes as a result of the formation and growth of hydroxyapatite crystals.

Investigation of a new design for zirconia dental implants

Objective:To assess the biomechanical properties of a new design configuration for zirconia dental implants. Methods: The new design has a cylindrical shape that is partially hollow and porous in the bottom, which permits the implants to be locked into the alveolar bone over time. It also utilizes bioactive glass coatings to increase adhesion to surrounding bone structure. Samples of the new design were fabricated in the laboratory and their material strength, hardness, and fracture toughness were evaluated. In addition, biocompatibility of the new design was evaluated through testing in dogs. Results: Results of mechanical tests indicate that structural properties of the new design exceed the usual requirements for implants. Moreover, animal tests suggest that there is appreciable improvement in lock-in strength and osteointegration. Conclusion: The new design configuration is biomechanically feasible and further research is warranted to improve the design for human use.

循环温度与咬合力作用下下颌中切牙瓷贴面三维有限元应力分析

目的:旨在采用三维有限元法研究下颌中切牙瓷贴面在循环温度与咬合力作用下应力分布的规律。方法:采用CBCT扫描下颌中切牙,建立下颌中切牙瓷贴面三维有限元模型,分别在循环温度、循环咬合力及循环温度叠加循环咬合力作用下,应用有限元分析软件分析下颌中切牙瓷贴面Von Mises应力、最大主应力(正值为拉应力,负值为压应力)的分布情况。结果:瓷贴面在低温循环作用下Von Mises应力值均大于高温循环作用下。在低温循环下,瓷贴面抛光面中央为拉应力集中区,最大主应力峰值为29.33 MPa。在高温循环下,瓷贴面组织面中央大部分区域为拉应力集中区,最大主应力峰值为9.25 MPa。在循环咬合力作用下,斜向循环加载时Von Mises应力峰值为40.22 MPa,正向循环加载Von Mises应力峰值为27.29 MPa。斜向循环加载时,瓷贴面的颈缘为拉应力集中区,最大主应力峰值为28.70 MPa。正向循环加载时,瓷贴面的切端加载区周围为拉应力集中区,最大主应力较小。在循环温度叠加循环咬合力作用下,瓷贴面在两种载荷叠加作用下的应力值大于单独循环温度与单独咬合力作用下的应力值。结论:单独循环温度、循环咬合力对瓷贴面的安全性影响较小,循环温度与循环咬合力有一定的协同作用。

Effect of Sintering Temperature on Aging Resistance and Mechanical Properties of 3Y-TZP Dental Ceramic

In order to investigate the effect of sintering temperature on aging properties and mechanical properties of 3Y-TZP dental ceramic in simulated oral environment, 3Y-TZP nanopowder compacts were pressurelessly sintered at 1 350℃, 1 400 ℃, 1 450 ℃,1 500 ℃, respectively, then were treated by soaking in artificial saliva （65 ℃, pH=7） for two months. The treated specimens sintered at 1 350 ℃ showed there was no phase transformation but whose strength and toughnesswere significantly improved （P〈0.05）, while those sintered at 1 400 ℃- 1 500 ℃ revealed a small amount of phase transformation and insignificant mechanical reinforcement （P〉0.05）. No microcracks were detected but increment in lattice volume was found in all specimens. Lowering sintering temperature favors aging resistance and mechanical reinforcement of 3Y-TZP in a simulated oral environment.

Effect of Diode Laser 810nm in Hardness of Dental Ceramic

This research study the effect of diode laser (810 nm), with various power (30, 200, 500) mW in hardness of the material used in the combinations of teeth (ceramics). Hardness was measured for dental ceramic samples divided into four groups, each group containing ten test sample, before and after it irradiated with the diode laser with wavelength 810 nm and different power (30, 200, 500) mW, with irradiation power of 200 mW for duration two minutes and ten minutes to the third and fourth groups, and irradiation power of 30 and 500 mW for duration one minute for the last two groups. The results showed that the increase in the irradiated time of the samples from two minutes to ten minutes, as well as increased power from 30 to 500 mW does not have a significant effect in increasing the hardness of the ceramic material. This study found that the hardness ratio of the samples was increased up to (18.28%), by irradiation of invisible diode laser 810 nm, 30 mW.

Insightful Understanding of the Role of the Mechanical Properties in Defining the Reliability of All-Ceramic Dental Restorations: A Review

Since the last two decades, restorative dentistry has been witnessing an increased acceptance of the use of the well-known all-ceramic materials for the fabrication of single dental restorations, such as inlays, onlays, crowns, anterior and posterior fixed partial dentures (PFPDs). These restorations certainly offer the potential for better biocompatibility coupled with superior aesthetic qualities, especially when compared with the conventional prostheses made from porcelain that is fused with metal ceramic restorations. However, brittleness and extreme sensitivity of all-ceramic materials to micro-like defects or cracks that are inherently present, or may grow, in their microstructure during different laboratory fabrication steps, during necessary clinical adjustments, or from post-placement chewing activity, remain major shortcomings of these dental restorations. In fact, many researchers are of the opinion that the improved mechanical properties can significantly improve the lifetime of all-ceramic restorations and result in enhanced reliability. Therefore, efforts of researchers, as well as manufacturers, have been directed towards the improvement of the mechanical properties in order to overcome such limitations. This article reviews the characterization of the most important mechanical properties that can delineate the behavior of all-ceramic dental materials upon loading. These include fracture mechanics, the brittle nature of ceramics, the relationship between microstructural features and fracture behavior, sources of cracks and flaws that may initiate a fracture and the effect of different fabrication procedures and/or clinical adjustments on the mechanical behavior of dental ceramics are also reviewed and discussed.

种植体支持的多单位螺丝固位氧化锆烤瓷与金属烤瓷修复体临床效果的比较研究

目的:比较种植体支持的螺丝固位氧化锆烤瓷修复体及金属烤瓷修复体的临床疗效。方法:对2011年1月~2016年9月就诊于首都医科大学附属北京口腔医院种植中心的患者进行随访,根据修复体材料分组,氧化锆烤瓷修复体组和金属烤瓷修复体组。统计比较两组在存留率、生物学并发症和机械并发症发生率方面的差异。结果:共纳入77例患者,91个修复体,233枚种植体。两组在存留率、生物学并发症和机械并发症方面的差异无统计学意义(P>0.05);两组最常见的机械并发症均为修复体崩瓷和松动。结论:两种不同材料修复体的临床疗效基本一致,种植体支持的螺丝固位氧化锆烤瓷修复体可获得稳定和可预期的远期临床疗效。

齿科修复用氧化锆陶瓷的增材制造现状及进展

氧化锆陶瓷因其高强度、耐腐蚀、菌斑黏附率低以及良好的生物相容性和美观性,成为牙科修复用全瓷材料的理想选择。但传统的减材制造工艺材料浪费严重,微小结构加工受限,难以高效生产优质产品。而增材制造技术的灵活性和自由度,不仅能实现牙科修复用氧化锆陶瓷高效快速制备,还能满足牙科领域精准、复杂的个性化需求。本文从氧化锆陶瓷材料性能、增材制造技术及应用三个方面,归纳了牙科修复用氧化锆陶瓷的研究进展,并对相关增材制造技术进行深入探讨,特别关注了光聚合成型、材料挤出和材料喷射等关键技术在牙科修复中的应用和前景。最后总结了本文的主要观点,并对未来增材制造牙科修复用氧化锆陶瓷的研究方向和可能的挑战进行了展望。

全瓷贴面技术用于前牙美容修复中的效果及对牙体形态、牙周健康指标的影响

目的探讨全瓷贴面技术用于前牙美容修复中的效果及对牙体形态、牙周健康指标的影响。方法选取2021年3月至2023年3月我院行前牙美容修复患者118例为研究对象,根据修复方法不同将患者分为两组,对照组(n=53例)行全瓷冠修复,观察组(n=65例)采用全瓷贴面技术修复。观察比较两组的临床疗效、牙体形态美学评分、修复前后牙周健康指标、修复后舒适度、并发症发生率及总体满意度情况。结果观察组临床总疗效96.92%显著高于对照组84.91%(P<0.05)。修复后,观察组边缘染色、边缘适应性、表面质地、颜色匹配、外形等牙体形态美学评分显著高于对照组(P<0.05)。修复后观察组的牙周探诊深度、龈沟出血指数、龈沟液量、菌斑指数等牙周健康指标水平显著低于对照组(P<0.05)。修复后两组环境、社会文化等舒适度评分比较无明显差异(P>0.05),但观察组心理、生理等舒适度评分显著高于对照组(P<0.05)。观察组总并发症发生率3.08%低于对照组18.87%(P<0.05)。观察组修复总满意度96.92%高于对照组84.91%(P<0.05)。结论全瓷贴面技术用于前牙美容修复中的效果显著,能提高临床疗效、牙体形态美学评分,改善牙周健康指标,提高舒适度,降低并发症发生率,提高患者满意度。

长石质陶瓷磨损研究及有限元数值模拟

利用高速环-块摩擦磨损实验机在10、20、30、40 N载荷下对Sirona CEREC Blocks长石质瓷块进行3.5×105周次磨损实验,得到磨损质量、磨损速率等参数与载荷、磨损周次的变化关系,根据所得变化关系将长石质陶瓷的磨损过程分为3个阶段,观察了各阶段的磨损表面形貌。对Archard磨损模型进行修正改进并通过ABAQUS中UMESHMOTION子程序开展有限元仿真研究。在ALE(Arbitrary Lagrangian-Eulerian)自适应网格区域选取两种节点路径,于3.0×10^(5)周次磨损工况下对4种不同载荷下的磨损深度进行仿真分析,并与实验值对比验证,结果表明10 N载荷工况下磨损深度的最大误差为12.18%,30 N载荷工况下磨损深度的最小误差为8.64%。

三维打印口腔修复种植体的研究进展

三维打印是计算机辅助制造的一种,通过三维打印设备,将数字化设计转化为实体。随着各种数字化手段的发展,三维打印已广泛应用于口腔修复体的制作。口腔种植义齿被称作人类第二副牙齿,以其美观、舒适等优点成为临床修复热点。目前,口腔种植体主要采用传统方法制造,三维打印可以提高种植体的个性化程度和制作效率。众多研究已证实,三维打印种植体是可行的,但在种植体设计、表面修饰等方面尚未有统一结论。本文通过阐述三维打印金属及全瓷种植体的最新研究进展,旨在带来种植体材料选择、制作工艺、表面设计及修饰等方面的思考,为三维打印种植体的进一步研究提供参考,以期更好地服务于临床。

研究牙体预备在口腔修复中的效果

目的探讨在口腔修复时不同牙体预备方法的临床效果。方法选取2021年2月—2024年2月江苏灌云县中医院进行口腔修复的80例患者为研究对象,根据不同牙体预备方法分为对照组和观察组,各40例。对照组采用常规预备修复,观察组采用烤瓷贴面切缘非包绕型预备修复。对比两组修复成功率、并发症发生情况、口腔功能、口腔修复满意度和复发率。结果观察组修复成功率为95.00%,高于对照组的80.00%,差异有统计学意义(χ^(2)=4.114,P<0.05)。两组并发症发生情况对比,差异无统计学意义(P>0.05)。修复后,观察组的咀嚼功能评分(85.69±9.72)分和语言功能评分(92.35±11.26)分均高于对照组,差异有统计学意义(P均<0.05)。观察组患者的口腔修复满意度高于对照组,复发率低于对照组,差异有统计学意义(P均<0.05)。结论在口腔修复时采用烤瓷贴面切缘非包绕型牙体预备修复成功率较高,且能保证良好的咀嚼功能和语言功能,减少复发,患者满意度较高。

全瓷高嵌体与全瓷冠修复治疗牙体缺损的效果分析

目的比较全瓷高嵌体与全瓷冠修复用于牙体缺损的治疗效果。方法选择2021年1月至2023年12月河南科技大学第二附属医院收治的70例牙体缺损患者作为研究对象。其中观察组35例患者采用全瓷高嵌体修复;对照组35例患者采用全瓷冠修复。比较两组患者治疗前后的牙周相关指标,治疗后的牙体修复效果。结果治疗3个月后,观察组患者优良率为97.14%(34/35)高于对照组80.0%(28/35),差异有统计学意义(P<0.05);观察组患者的探诊出血指数、牙龈指数较疗前低于对照组,差异有统计学意义(P<0.05);观察组患者修复体边缘适合性、外形评分均高于对照组,差异有统计学意义(P<0.05)。结论全瓷高嵌体修复牙体缺损可有效改善患者牙周症状,修复体边缘适合性及外形较好,修复效果理想。

铸瓷贴面与烤瓷全冠在口腔美学修复中的应用效果及对牙周情况的影响

目的探讨口腔美学修复中采用铸瓷贴面与烤瓷全冠的应用效果及对牙周情况的影响。方法选取2022年5月至2023年9月本院收治的口腔美学修复患者共计106例,根据治疗方法的不同分成研究组(n=53)与对照组(n=53),对照组采用烤瓷全冠修复,研究组采用铸瓷贴面修复,对两组修复美观度、牙周情况、并发症发生率及修复满意度进行比较。结果修复后两组形态、颜色、边缘美观、半透明程度评分升高(P<0.05),研究组较对照组更高(P<0.05);修复后两组牙龈出血指数(BI)、附着丧失(AL)、牙周袋深度(PD)下降(P<0.05),研究组较对照组更低(P<0.05);统计并发症发生率,研究组(3.77%)较对照组(18.87%)更低(P<0.05);统计修复满意度,研究组(98.11%)较对照组(84.91%)更高(P<0.05)。结论与烤瓷全冠相比,铸瓷贴面应用于口腔美学修复中能够提高修复美观度,改善牙周情况,减少并发症发生,提高修复满意度。