Marginal fit of anterior 3-unit fixed partial zirconia restorations using different CAD/CAM systems

PURPOSE

Few studies have investigated the marginal accuracy of 3-unit zirconia fixed partial dentures (FPDs) fabricated by computer-aided design/computer-aided manufacturing (CAD/CAM) system. The purpose of this study was to compare the marginal fit of zirconia FPDs made using two CAD/CAM systems with that of metal-ceramic FPDs.

MATERIALS AND METHODS

Artificial resin maxillary central and lateral incisors were prepared for 3-unit FPDs and fixed in yellow stone. This model was duplicated to epoxy resin die. On the resin die, 15 three-unit FPDs were fabricated per group (45 in total): Group A, zirconia 3-unit FPDs made with the Everest system; Group B, zirconia 3-unit FPDs made with the Lava system; and Group C, metal-ceramic 3-unit FPDs. They were cemented to resin dies with resin cement. After removal of pontic, each retainer was separated and observed under a microscope (Presize 440C). Marginal gaps of experimental groups were analyzed using one-way ANOVA and Duncan test.

RESULTS

Mean marginal gaps of 3-unit FPDs were 60.46 µm for the Everest group, 78.71 µm for the Lava group, and 81.32 µm for the metal-ceramic group. The Everest group demonstrated significantly smaller marginal gap than the Lava and the metal-ceramic groups (P<.05). The marginal gap did not significantly differ between the Lava and the metal-ceramic groups (P>.05).

CONCLUSION

The marginal gaps of anterior 3-unit zirconia FPD differed according to CAD/CAM systems, but still fell within clinically acceptable ranges compared with conventional metal-ceramic restoration.     

Load-bearing capacity of all-ceramic three-unit fixed partial dentures with different computer-aided design (CAD)/computer-aided manufacturing (CAM) fabricated framework materials

The purpose of this in vitro study was to compare the load-bearing capacity of posterior three-unit fixed dental prostheses (FDP) produced with three different all-ceramic framework materials: glass-infiltrated alumina (ICA), glass-infiltrated alumina strengthened with zirconia (ICZ), and yttria-stabilized polycrystalline zirconia (YZ). Additionally, the influence on aging of mechanical cyclic fatigue loading and thermal cycling in water were evaluated. A total of 20 frameworks each were fabricated from ICA, ICZ, and YZ by a computer-aided design (CAD)/computer-aided manufacturing (CAM) system. The framework designs were identical for all specimens. All frameworks were veneered with porcelain and cemented with glass–ionomer. Prior to fracture testing, 10 FDP of each experimental group were subjected to thermal and mechanical cycling. Additionally, fractographic analysis was performed. Statistical analysis showed that FDP made from YZ had significantly higher load to failure, whereas no difference was found between the other two materials. Aging did not have a significant effect on the fracture load.     

CAD/CAM氧化锆全瓷冠修复临床疗效评价

目的：探讨CAD／CAM氧化锆全瓷冠的修复效果。方法：选择82例（192颗患牙）,分别在CAD／CAM氧化锆全瓷冠粘接后1、3、6、12个月进行随访观察。采用美国公共健康协会的修订标准对修复体的临床效果进行评价。结果：观察期间失访4例,随访78例共181件修复体,结果显示CAD／CAM全瓷冠颜色达到好以上91．2％,CAD／CAM氧化锆全瓷冠的崩瓷率2．76％,与修复体部位有明显相关性（P〈0．01）,在粘接12个月后有1个修复体的边缘密合度欠佳,所有复诊患者在12个月的临床观察中均未见边缘着色,继发龋和基牙松动。结论：氧化锆全瓷修复体具有良好的稳定性和生物相容性,近期临床效果满意。     

不同颈缘弯曲度和肩台形态的泽康全瓷冠的精度

目的调查不同颈缘弯曲度和肩台形态的泽康CAD／CAM全瓷冠的边缘精度。方法准备6种不同形态的基牙（弯曲度：1mm,3mm,5ram;肩台外形：圆弧肩台,直角肩台）。制作30个泽康CAD／CAM全瓷冠（每种肩台各5个）,测定陶瓷基底冠和全瓷冠的边缘缝隙。采用双因子ANOVA分析后用T检验测定有无统计学差异。结果弯曲度1mm,3mm,5mm圆弧肩台的泽康全瓷冠的边缘缝隙分别为51（21）μm,53（22）μm,54（20）μm。弯曲度1mm,3mm,5mm直角肩台的泽康全瓷冠的边缘缝隙分别为49（18）μm,51（19）μm,50（22）μm。统计结果显示6种基牙之间没有显著性差异。结论泽康全瓷冠有良好的边缘精度,颈缘弯曲度和肩台形态对泽康全瓷冠的边缘精度没有显著影响。     

全瓷固定桥的应用现状

随着高强度陶瓷材料的出现,全瓷固定桥以其优良的耐腐蚀性、耐磨损性、独特的美学性能和极佳的生物相容性逐步代替金属材料和其他高分子材料,被认为是牙列缺损固定修复发展的方向。但其脆性大,在长期咀嚼力作用下易发生断裂,因此如何通过改良全瓷固定桥的材料性能及临床设计来延长全瓷固定桥的使用寿命成为近年来研究热点之一。本文就全瓷固定桥的材料分类、受力分布及临床设计等研究现状进行综述。     

CAD/CAM氧化锆全瓷与IPS e.max Press铸瓷固定局部义齿修复的临床对比研究

目的：比较不同全瓷系统用于前牙及前磨牙区固定桥修复的临床效果。方法选取20～60岁因前牙或第一前磨牙缺失而行3单位固定桥修复的患者,随机分成CAD/CAM氧化锆和IPS e.max Press两组,分别在修复体戴入后3、6、12个月,临床观察其是否发生脱落、折裂、崩瓷、修复体边缘密合性及牙龈表现,参照改良美国公共卫生署评价标准进行疗效评价,并进行统计学分析。结果随着时间的延长,两种全瓷材料的固定修复成功率均有所下降,但均在90%以上,两者之间差异无统计学意义（P＞0.05）。结论在严格控制临床适应证的前提下,CAD/CAM二氧化锆与IPS e.max Press两种全瓷材料均能达到良好的修复效果。     

Load-bearing capacity of all-ceramic posterior four-unit fixed partial dentures with different zirconia frameworks

The aim of this in vitro study was to compare the load-bearing capacity of posterior four-unit fixed partial dentures (FPDs) produced with two different yttria-stabilized polycrystalline tetragonal zirconia (Y-TZP) ceramics, one being a presintered material, the other a fully sintered, hot isostatically pressed material. Additionally, as a novel approach, the influence of preliminary mechanical damage upon the fracture force of an FPD has been investigated. A total of 20 frameworks each were milled from presintered zirconia and from fully sintered zirconia. Prior to veneering, 10 frameworks of each material were 'damaged' by a defined saw cut similar to an accidental flaw generated during shape cutting. Before fracture testing, all FPDs were subjected to thermal and mechanical cycling. Additionally, scanning electron microscopy was used to investigate fracture surfaces. Statistical analysis showed that FPDs milled from fully sintered zirconia had a significantly higher fracture resistance compared with specimens made from presintered material, whereas preliminary damage did not have a significant effect. After aging, FPDs made from both materials were capable of withstanding occlusal forces reported in the literature. Therefore, both types of Y-TZP may be suitable for posterior four-unit all-ceramic FPDs, although further prolonged aging experiments and prospective clinical trials are required to prove their fitness for clinical use.     

双排龈技术在CAD/CAM全瓷修复中的临床应用

目的：评价双排龈技术在CAD/CAM全瓷修复中的临床应用效果。方法：对30例48单位前牙行CAD/CAM全瓷修复,牙体预备后采用双排龈技术进行排龈,检查牙龈及预备体、光学印模以及修复体边缘情况。结果：双排龈技术的满意率分别为97.91%,95.83%,100.0%。结论：双排龈技术在CAD/CAM全瓷修复时具有很好的应用效果。     

Marginal and internal fit of heat pressed versus CAD/CAM fabricated all-ceramic onlays after exposure to thermo-mechanical fatigue

Objectives

The aim of the study was to evaluate the marginal and internal fit of heat-pressed and CAD/CAM fabricated all-ceramic onlays before and after luting as well as after thermo-mechanical fatigue.

Materials and methods

Seventy-two caries-free, extracted human mandibular molars were randomly divided into three groups (n = 24/group). All teeth received an onlay preparation with a mesio-occlusal–distal inlay cavity and an occlusal reduction of all cusps. Teeth were restored with heat-pressed IPS-e.max-Press* (IP, *Ivoclar-Vivadent) and Vita-PM9 (VP, Vita-Zahnfabrik) as well as CAD/CAM fabricated IPS-e.max-CAD* (IC, Cerec 3D/InLab/Sirona) all-ceramic materials. After cementation with a dual-polymerising resin cement (VariolinkII*), all restorations were subjected to mouth-motion fatigue (98 N, 1.2 million cycles; 5 °C/55 °C). Marginal fit discrepancies were examined on epoxy replicas before and after luting as well as after fatigue at 200× magnification. Internal fit was evaluated by multiple sectioning technique. For the statistical analysis, a linear model was fitted with accounting for repeated measurements.

Results

Adhesive cementation of onlays resulted in significantly increased marginal gap values in all groups, whereas thermo-mechanical fatigue had no effect. Marginal gap values of all test groups were equal after fatigue exposure. Internal discrepancies of CAD/CAM fabricated restorations were significantly higher than both press manufactured onlays.

Conclusions

Mean marginal gap values of the investigated onlays before and after luting as well as after fatigue were within the clinically acceptable range. Marginal fit was not affected by the investigated heat-press versus CAD/CAM fabrication technique. Press fabrication resulted in a superior internal fit of onlays as compared to the CAD/CAM technique.

Clinical relevance

Clinical requirements of 100 μm for marginal fit were fulfilled by the heat-press as well as by the CAD/CAM fabricated all-ceramic onlays. Superior internal fit was observed with the heat-press manufacturing method. The impact of present findings on the clinical long-term behaviour of differently fabricated all-ceramic onlays warrants further investigation.     

Clinical and SEM evaluation of all-ceramic chair-side CAD/CAM-generated partial crowns

The effect of hardware and software on the quality of Cerec all-ceramic partial crowns was investigated in this cross-sectional study. Partial crowns (n = 818) had been adhesively placed in 496 patients between 1993 and 1997 using Cerec 1 and Cerec 2 units (groups 1 and 2) as well as Cerec 2 with wall-spacing software (group 3). From each group, 25 randomly selected partial crowns were evaluated using modified United States Public Health Service (USPHS) criteria. Of these, 12 were randomly selected in each group, replicas taken and examined in a scanning electron microscope for marginal interfacial width and for continuous margin adaptation. Interfacial width of group 1 (308 +/- 95 micro m) was significantly larger than those of groups 2 (243 +/- 48 micro m) and 3 (207 +/- 63 micro m). Continuous margin adaptation at the tooth-luting composite and luting composite-restoration interfaces showed only minor differences in groups 1 (94.5 +/- 8% and 95.5 +/- 2%), 2 (98.1 +/- 1% and 97.5 +/- 1.4%) and 3 (96.8 +/- 3% and 96.8 +/- 2%). Pooled clinical rating was excellent or good at 97% for all groups, indicating acceptable restoration quality except for one breakage in group 1.     

不同基牙设计对CAD/CAM全瓷修复体抗折强度的影响

目的 研究不同CAD/CAM全瓷修复体修复根充后前磨牙的抗折强度。方法 收集21颗因正畸拔除的上颌第一前磨牙,制备近面及舌尖缺损洞型。样品分为3组,第1组为直接树脂充填组;第2组为保留缺损组;第3组为纤维桩核组,然后利用IPS e.max CAD全瓷修复体进行修复,采用Rely X U200树脂黏结剂进行黏固。对所有样品进行抗折强度测试,采用光学显微镜观察样品的断裂类型。采用SPSS 15.0软件包对数据进行统计学分析。结果 纤维桩核组全瓷修复体的抗折强度显著大于树脂充填组和保留缺损组。第1组和第2组以修复体破裂为主,第3组除修复体破裂外,还发生牙体组织破裂。结论 对于伴有功能牙尖缺损的前磨牙,建议采用纤维桩核+全瓷冠进行修复。     

Fracture resistance of different zirconium dioxide three-unit all-ceramic fixed partial dentures

OBJECTIVE: This study evaluated the fracture resistance of different zirconia three-unit posterior all-ceramic fixed partial dentures before and after fatigue loading. MATERIAL AND METHODS: Forty-eight zirconia three-unit posterior all-ceramic fixed partial dentures were fabricated using different manufacturing systems and conventionally cemented on human teeth. The restorations were divided according to the system used for manufacturing the frameworks into 3 groups of 16 specimens each (DCS, Procera and Vita CerecInlab). Half of each group was artificially aged through dynamic loading and thermal cycling, whereas the other half was left with no artificial aging. Afterwards, all specimens were tested for fracture resistance using compressive load on the occlusal surface. Non-parametric ANOVA using the Kruskal-Wallis and Wilcoxon rank tests was performed to test for differences in fracture resistance values with a global significance level of 0.05. RESULTS: All artificially aged specimens survived with no failures. The median fracture resistance values (before; after artificial aging) were: DCS (1683 N; 1618 N), Procera (1522 N; 1256 N), and Vita CerecInlab (1702 N; 1556 N). No significant differences were found for comparisons between different groups before artificial aging. Artificial aging did not significantly influence the fracture resistance of different groups. After artificial aging, group Procera showed significantly lower fracture resistance than the Vita CerecInlab (p=0.015) and DCS (p=0.038) groups. CONCLUSIONS: All tested restorations have the potential to withstand occlusal forces applied in the posterior region and can therefore represent interesting alternatives for replacing porcelain-fused-to-metal restorations. Further assessment is needed before recommending such restorations in daily practice.     

CAD/CAM systems,materials, and clinical guidelines for all-ceramic crowns and fixed partial dentures

Advances in dental ceramic materials and the development of computer-aided design/computer-aided manufacturing (CAD/CAM) and milling technology have facilitated the development and application of superior dental ceramics. CAD/CAM allows the use of materials that cannot be used with conventional dental processing techniques. This article reviews the main techniques and new materials used in dentistry for CAD/CAM-generated crowns and fixed partial dentures. Also covered are the clinical guidelines for using these systems.     

Influence of porcelain veneering on the marginal fit of Digident and Lava CAD/CAM zirconia ceramic crowns

PURPOSE

Marginal fit is a very important factor considering the restoration''s long-term success. However, adding porcelain to copings can cause distortion and lead to an inadequate fit which exposes more luting material to the oral environment and causes secondary caries. The purpose of this study was to compare the marginal fit of 2 different all-ceramic crown systems before and after porcelain veneering. This study was also intended to verify the marginal fit of crowns originated from green machining of partially sintered blocks of zirconia (Lava CAD/CAM system) and that of crowns obtained through machining of fully sintered blocks of zirconia (Digident CAD/CAM system).

MATERIALS AND METHODS

20 crowns were made per each system and the marginal fit was evaluated through a light microscope with image processing (Accura 2000) at 50 points that were randomly selected. Each crown was measured twice: the first measurement was done after obtaining a 0.5 mm coping and the second measurement was done after porcelain veneering. The means and standard deviations were calculated and statistical inferences among the 2 groups were made using independent t-test and within the same group through paired t-test.

RESULTS

The means and standard deviations of the marginal fit were 61.52 ± 2.88 µm for the Digident CAD/CAM zirconia ceramic crowns before porcelain veneering and 83.15 ± 3.51 µm after porcelain veneering. Lava CAD/CAM zirconia ceramic crowns showed means and standard deviations of 62.22 ± 1.78 µm before porcelain veneering and 82.03 ± 1.85 µm after porcelain veneering. Both groups showed significant differences when analyzing the marginal gaps before and after porcelain veneering within each group. However, no significant differences were found when comparing the marginal gaps of each group before porcelain veneering and after porcelain veneering as well.

CONCLUSION

The 2 all-ceramic crown systems showed marginal gaps that were within a reported clinically acceptable range of marginal discrepancy.     

CADCAM瓷贴面修复的临床效果探析

[摘要] 目的 评价CAD/CAM全瓷贴面修复前牙的临床效果。方法 选择98颗前牙,采用CEREC的椅旁CAD/CAM修复系统及IPS e.max CAD瓷块即刻完成修复体并粘结。参照改良Ryge评价方法,对临床使用1周、6个月、12个月、24个月的贴面在颜色匹配、瓷表面完整度、边缘染色、边缘适应性、术后敏感、牙龈健康状况、继发龋方面进行临床评价。结果 CAD/CAM全瓷贴面在这些方面的临床评级,90%以上达到A级。结论 用CEREC的椅旁CAD/CAM修复系统及IPS e.max CAD瓷块完成的贴面临床效果良好可靠。     

椅旁CAD/CAM系统与技工室制作全锆冠的临床比较研究

目的:比较CEREC AC椅旁CAD/CAM系统与技工室WIELAND系统制作氧化锆全锆冠的临床修复效果.方法:采用CEREC AC椅旁CAD-CAM系统制作磨牙区全锆冠,并与技工室WIELAND系统制作的全锆冠进行修复体外观形态、边缘密合度、牙龈情况和颜色匹配方面的比较.用满意度评价修复体的各项临床指标,用统计学方法比较两组的差异.结果:各项指标中颜色匹配效果满意度稍低(12/20比14/20);在修复体外观形态、边缘密合度、牙龈情况等方面满意度高(18/20).两组试验数据统计结果P＞ 0.05.提示两种加工方式制作的修复体的临床效果差异无统计学意义.结论:CEREC AC椅旁CAD/CAM系统与技工室WIELAND系统制作的氧化锆全锆冠的临床效果评价无明显差异.CEREC AC椅旁CAD/CAM系统还可以为患者提供更为快捷的服务.     

不同全瓷材料在CAD/CAM系统中的边缘适合性研究

目的 研究不同全瓷材料由同一种CAD/CAM系统制作后其边缘适合性的差异,观察不同材料在烧结、结晶、上釉前后的边缘适合性变化,为临床选择全瓷材料提供一定的参考依据。方法 制作前磨牙牙备后树脂试件,分别使用长石类全瓷材料,二硅酸锂全瓷材料和氧化锆全瓷材料在SironainLab CAD/CAM系统中制作全瓷修复体各8个,在体视显微镜下观察各冠边缘与试件间隙。结果 在基底冠和全冠两个阶段的边缘间隙,长石类分别为（59.18±8.15）μm和（59.78±8.47）μm,二矽酸锂类分别为（56.16±6.64）μm和（57.22±7.45）μm,氧化锆类分别为（18.12±4.69）μm和（22.36±4.48）μm。其中,长石类与二矽酸锂类的边缘间隙差异无统计学意义（P>0.05）,但他们与氧化锆类比较,差异有统计学意义（P<0.05）。而同组的修复体在两阶段的数据差异均无统计学意义（P>0.05）。结论 三种材料制作的全冠适合性均在临床可接受的范围内,但氧化锆组更接近美国牙科协会的标准,值得推广应用。     

CAD/CAM锆瓷冠在后牙种植修复中的临床应用

目的：探讨CAD/CAM锆瓷冠在后牙种植体修复的临床应用。方法：选取ITI种植术后病例30例,采用CAD/CAM全瓷冠修复,3年后复查,对修复效果进行评价。结果：经6-36个月随访观察发现1例饰瓷脱落外,其余修复体均正常：全冠的形状、颜色与邻牙相协调,全冠修复体未见有明显磨耗,冠颈缘与基台密合度良好,近远中邻接面接触关系正常,龈周组织正常,未见有破损与脱落,修复成功率为97%,效果满意。结论：CAD/CAM锆瓷冠在后牙种植修复中的临床应用效果良好,值得推广。     

CAD/CAM一体化氧化锆桩核的临床评价

目的:观察CAD/CAM一体化氧化锆桩核在修复前牙残冠、残根中的临床效果。方法:本研究对45颗残冠、残根使用自凝塑料在口中制作桩核模型,应用CAD/CAM技术切削出一体化氧化锆桩核,运用一体化氧化锆桩和全瓷冠修复所有残冠、残根,经3年的临床跟踪,观察其临床效果。结果:观察期间失访2例患者,因此只对剩余43件修复体进行复查,其中中切牙28例,侧切牙7例,尖牙8例。2例患牙在第6个月时出现牙龈炎。1例右上中切牙氧化锆桩核修复体在第12个月后出现I-II°松动,1例右上侧切牙桩核修复体在第18个月后松动脱落。24个月和30个月时分别有1例患牙出现根折。所有复诊患者在36个月的临床观察中均未见桩核折断、边缘着色和继发性根尖周炎,并且所有修复体均获得满意美观效果。结论:CAD/CAM一体化氧化锆桩具有良好的美学效果和生物相容性,近期临床效果满意。