In vivo wear of enamel by a lithia disilicate-based core ceramic used for posterior fixed partial dentures: first-year results

PURPOSE: This study aimed (1) to test the hypothesis that no significant relationship exists between the magnitude of occlusal clenching force and wear rates of enamel opposing a new core ceramic (e.max Press, Ivoclar Vivadent) used in posterior fixed partial dentures (FPDs); and (2) to test the hypothesis that mean annual enamel wear by an experimental core ceramic is comparable to the mean annual enamel wear by enamel of 38 microm. MATERIALS AND METHODS: Baseline data were obtained for patients in addition to preliminary impressions of maxillary and mandibular teeth. Thirty ceramic FPDs were processed from a new core ceramic (e.max Press) that was hot pressed and glazed. Patients were recalled 1 year after cementation and evaluated using clinical criteria that included wear assessment of opposing teeth. Impressions were made of the opposing teeth with polyvinylsiloxane impression material and photographs were taken of intraoral occlusal contacts marked with articulating ribbon. Baseline casts and casts made at each recall exam of opposing dentitions were scanned using a 3-dimensional laser scanner (Laserscan 3D, Willytec) and evaluated for wear. A total of 21 occlusal surfaces were analyzed for the presence of wear. RESULTS: Statistical analysis using a linear and quadratic model revealed no significant relationship between occlusal forces and wear rate assuming either a linear model (R2 = 0.018) or a quadratic model (R2 = 0.023). The maximum annual wear of enamel by the glazed core ceramic (e.max Press) was 88.3 microm, which is significantly greater than the annual enamel-by-enamel wear of 38 microm (P < .0001). CONCLUSION: Further analysis with a larger sample size is needed to determine the relationship between occlusal clenching force and wear rate and the influence of other factors that cause increased wear of enamel by opposing ceramic restorations.     

Clinical performance of a lithia disilicate-based core ceramic for three-unit posterior FPDs

PURPOSE: The purpose of this research project was to determine the clinical success rate of a lithia disilicate-based core ceramic for use in posterior fixed partial dentures (FPD) as a function of bite force, cement type, connector height, and connector width. MATERIALS AND METHODS: Thirty ceramic FPD core frameworks were prepared using a heat-pressing technique and a lithia disilicate-based core ceramic. The maximum clenching force was measured for each patient prior to tooth preparation. Connector height and width were measured for each FPD. Patients were recalled yearly after cementation for 2 years and evaluated using 11 clinical criteria. All FPDs were examined by two independent clinicians, and rankings from 1 to 4 were made for each criterion (4 = excellent; 1 = unacceptable). RESULTS: Two of the 30 ceramic FPDs fractured within the 2-year evaluation period, representing a 93% success rate. One fracture was associated with a low occlusal force and short connector height (2.9 mm). The other fracture was associated with the greatest occlusal force (1,031 N) and adequate connector height. All criteria were ranked good to excellent during the 2-year recall for all remaining FPDs. CONCLUSION: The performance of the experimental core ceramic in posterior FPDs was promising, with only a 7% fracture rate after 2 years. Because of the limited sample size, it is not possible to identify the maximum clenching force that is allowable to prevent fracture caused by interocclusal forces.     

Tooth preparations designed for posterior resin-bonded fixed partial dentures: a clinical report

Numerous designs for posterior resin-bonded fixed partial dentures have been reported in the dental literature, but a methodical technique is still lacking. A groove, plate, and strut approach involving minimal preparation of posterior abutments to receive a resin-bonded fixed partial dentures is presented. The essential clinical and laboratory procedures are illustrated.     

Six-year clinical performance of lithium disilicate fixed partial dentures

The aim of this randomized controlled trial was to evaluate the clinical performance of lithium disilicate fixed partial dentures (FPDs). Eighteen patients received lithium disilicate FPDs (study group), and 19 patients received porcelain-fused-to-metal FPDs (control). After 6 years, the survival probabilities were found to be 63% in the study group and 95% in the control group (log-rank test, P = .028). The data suggest that strict conditions should be considered before the use of lithium disilicate glass-ceramic for FPDs.     

Work of adhesion of resin on treated lithia disilicate-based ceramic.

OBJECTIVE: This study is to test the hypothesis that chemical etching and silane coating of a ceramic surface will influence the work of adhesion (WA) of adhesive resin to dental ceramic. METHODS: A hot-pressed lithia disilicate-based ceramic was used as a model material to investigate the influence of probing media and surface treatments on WA using a dynamic contact angle analyzer. Eighty ceramic specimens were randomly divided into eight experimental groups and treated as follows: (1 and 3) as polished; (2 and 4) etched with 9.5% hydrofluoric acid (HF) for 1 min; (5) etched with 4% acidulated phosphate fluoride (APF) for 2 min; (6) silane coated; (7) etched with HF for 1 min and silane coated; (8) etched with APF for 2 min and silane coated. Advancing and receding contact angles (theta(a) and theta(r)) were measured using high purity water (gamma = 72.6 mN/m) for groups 1 and 2, and a liquid resin (gamma = 39.7) for groups 3-8 as probing liquids. RESULTS: The liquid resin medium yielded a lower WA than water. Silanization produced a significantly lower WA (p < 0.001) than non-silanated surfaces. Etching alone consistently yielded a greater WA for all surface treatments (p < 0.001). SIGNIFICANCE: The silanated ceramic surface exhibited a lower surface energy and did not enhance bonding to the liquid resin by work of adhesion.     

后牙金属烤瓷桥舌侧支架改良设计对瓷抗折力的影响

目的:比较后牙烤瓷桥桥体舌侧金属支架结构改良对于瓷抗折强度的影响.方法:制作下颌第一磨牙无牙尖烤瓷桥15例,分为3组,两实验组样本采用舌侧金属支架结构改良,所有样本经3DX-CT确定应力加载点后,利用万能测试机垂直于检测样面加压,测定瓷折裂时的应力值并作统计分析,另一组为对照组.结果:对照组样本的平均瓷折裂值为(1592.038±267.908)N,实验一组与实验二组的平均值为(2493.934±218.843)N和(1860.654±229.553)N,3组问存在非常显著性差异.实验一组的瓷折裂值明显高于其他两组.结论:经桥体舌侧金属支架结构改良后桥体舌侧边缘瓷折裂平均值明显增高,该设计可能有助于增强后牙烤瓷桥体的瓷抗折强度,延长烤瓷桥的使用寿命.     

Marginal fit of Zirconia posterior fixed partial dentures

The aim of this study was to investigate the marginal fit of posterior fixed partial dentures (FPDs) made with 2 computer-aided design/computer-assisted manufacture systems--Procera Bridge Zirconia (Nobel Biocare) and Lava AllCeramic System (3M ESPE)--and to analyze the differences between abutments and between buccal and lingual surfaces. Twenty standardized specimens were prepared to receive posterior 3-unit FPDs. FPDs were fabricated according to the manufacturer's instructions. A scanning microscope (JSM-6400, JEOL) with a magnification of 1,000x was used for measurements. Three-way analysis of variance showed significant differences (P < .001) in marginal adaptation between the ceramic groups. Procera Bridge Zirconia showed the lowest discrepancies (26 +/- 19 microm). No significant differences were observed between abutments and surfaces, and no significant interaction was observed among the ceramic system, abutments, and surfaces. The accuracy of fit achieved by both zirconia systems was within the range of clinical acceptability, with Procera Bridge Zirconia showing the best marginal fit.     

Long-term clinical performance of resin-bonded fixed partial dentures with retentive preparation geometry in anterior and posterior areas

PURPOSE: The aim of this prospective clinical evaluation was to show the long-term clinical behavior of resin-bonded fixed partial dentures (RBFPD) with a retentive, minimally invasive preparation design. MATERIALS AND METHODS: Since 1985, 232 RBFPDs with a retentive preparation design were placed under controlled clinical conditions. In 2005 and 2006, 84 fixed partial dentures could be re-evaluated. Using Kaplan-Meier analysis, the survival rate was determined. The probability of survival was calculated with several risk factors: location (anterior/posterior, maxilla/mandible), metal alloy of the framework (titanium/CoCr), number of pontics, and number of supporting teeth. RESULTS: A total of 12 failures was observed and resulted in a survival rate of 77% after 10 years. However, only 4 catastrophic failures occurred. In such cases, the restoration was lost, or could not be re-bonded or repaired (survival rate 88% after 10 years). RBFPDs made of a titanium alloy exhibited a statistically significantly higher survival rate than RBFPDs made of a nonprecious CoCr alloy in terms of all failures. Only slight but not statistically significant differences between the covariates maxilla, mandible, anterior/posterior region, number of pontics, and number of abutment teeth were observed. CONCLUSION: Within the limitations of this study, RBFPDs seem to be a reliable restorative alternative to conventional short-span fixed dental prostheses.     

Fracture strength of all-ceramic posterior inlay-retained fixed partial dentures

OBJECTIVES: The purpose of this in vitro study was to compare the quasi-static (QSFS) and fatigue fracture strength of all-ceramic resin-bonded three unit inlay-retained fixed partial dentures (IRFPDs) made from a heat-pressed lithium-disilicate based glass-ceramic (LDGC) and a CAD/CAM-manufactured yttrium-oxide partially stabilized zirconia framework (YPSZ). METHODS: Identical IRFPD-models of the maxilla were used. They consisted of a second premolar, a missing first molar and a second molar (Co-Cr-Mo alloy) integrated in a low melting alloy base. Roots were covered with a soft silicone-layer to simulate an artificial parodontium. Premolars had an occlusal-distal inlay-preparation and molars a mesial-occlusal inlay-preparation. Thirty-two IRFPDs were made from each ceramic using two different connector dimensions: 3mmx3mm (LDGC_9, YPSZ_9); 4mmx4mm (LDGC_16, YPSZ_16). All IRFPDs were cemented adhesively to the IRFPD-models, using composite resin cement. QSFS was tested in a universal-testing-machine (UTM) for six specimens. The other specimens were fatigued either with cyclic loading at 250N (n=4) in a chewing simulator or at 600N (n=6) using the UTM, and group YPSZ additionally at 1500N. RESULTS: The medians of QSFS (N) were 960 (LDGC_9), 1316 (LDGC_16), 3180 (YPSZ_9) and 3120 (YPSZ_16). For both QSFS and cyclic loading significant differences were found between LDGC_9 and LDGC_16 (p0.05). Differences between LDGC and YPSZ were significant for both connector sizes (p相似文献   

前牙氧化锆全瓷粘接桥两年临床应用效果观察

目的 观察前牙氧化锆全瓷粘接桥的修复效果,为氧化锆全瓷粘接桥修复的适应证选择和临床应用提供参考.方法 选择23例单颌缺失1～2颗前牙的患者,进行单翼或双翼氧化锆全瓷粘接桥修复.随访时根据美国公共健康协会标准,观察粘接桥的完整性、边缘着色、继发龋和颜色匹配性.结果 共制作粘接桥29件,其中单翼粘接桥23件,双翼粘接桥6件.观察14～30个月,平均22个月.1件双翼粘接桥修复失败,2件单翼粘接桥修复失败.26件粘接桥无边缘着色,无继发龋,仅2件单翼粘接桥颜色偏白.粘接桥累积生存率为90%(26/29).结论 对单颌缺失1～2颗前牙的患者进行氧化锆全瓷粘接桥修复,可以达到恢复前牙美观和功能的效果.     

Retainer design for posterior resin-bonded fixed partial dentures: a technical report.

This article describes a new posterior preparation and retainer design for resin-bonded fixed partial dentures to resist eccentric loading, using a noble alloy (a silver-palladium-copper-gold alloy), a recently developed metal adhesive conditioner (Metaltite), and an adhesive resin-luting agent (Super-Bond C&B).     

Proximal contour modifications for fixed partial dentures: a clinical report

An often-neglected aspect of fixed prosthodontics is the contour of the tooth adjacent to the cast restoration. The adjacent surfaces should be surveyed to reveal compatibility with the path of insertion of the restoration. Adjacent contacts may have to be altered to permit the placement of the fixed partial denture and to ensure proper contact size/shape and embrasure size. The need for guide planes on teeth adjacent to fixed partial denture abutments in fixed prosthodontics is described.