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Metal-ceramic Crowns (metal-ceramic + crown)

Distribution by Scientific Domains

Medical Sciences	100%

Selected Abstracts

Precision of Fit of Two Margin Designs for Metal-Ceramic Crowns

JOURNAL OF PROSTHODONTICS, Issue 4 2007
Penwadee Limkangwalmongkol DDS
Statement of Problem: Although metal-ceramic restorations are widely used, there is a lack of information about how the fit is affected by margin designs. Purpose: This study measured and compared the precision of fit of metal-ceramic crowns with two margin designs. Material and Methods: Thirty-two extracted human premolar teeth were prepared for complete-coverage restorations with an internally rounded shoulder preparation. Impressions were made from all teeth, and master dies were poured with improved stone type V. MC crowns were fabricated with a porcelain-butt margin on the buccal aspect (n = 32) and a feather-edge metal margin on the lingual aspect (n = 32), which served as a control group. Precision of fit was measured three times at the mid-buccal and mid-lingual margins of each crown with a profilometer. The data were statistically analyzed with the paired t -test (, < .05). Results: Mean marginal gap size of porcelain-butt margins was 27.93 ,m (±15.84) and of feather-edge metal margins 42.43 ,m (±24.12). The marginal gap size of feather-edge metal margins was statistically significantly greater than that of porcelain-butt margins (p = 0.0045). Conclusion: The marginal fit of porcelain-butt margins was significantly better than that of feather-edge metal margins. Clinical Implications: Porcelain-butt margins in this study had a better marginal fit than feather-edge metal margins, and thus have given clinicians evidence to prefer the use of porcelain-butt margins. [source]

Comparison of Repair Methods for Ceramic-Fused-to-Metal Crowns

JOURNAL OF PROSTHODONTICS, Issue 5 2006
Mutlu Özcan DMD
Purpose: The objective of this study was to evaluate the effect of four repair methods on the fracture load of repaired ceramic-fused-to-metal crowns. Materials and Methods: Metal-ceramic crowns were fractured, and the failure load was measured. The fractured metal-ceramic crowns (n = 9) were assigned randomly to the following treatment groups: (1) hydrofluoric acid (9.5%) etching, (2) air-particle abrasion (50 ,m Al2O3), (3) silica coating (30 ,m SiOx), and (4) the application of a layer of glass fiber-reinforced composite (FRC) (thickness: 0.12 mm) on the repair surface. The crowns were repaired with a highly filled resin composite and subjected to 3 repair cycles (n = 27). All specimens were stored in water at 37°C for 24 hours and then thermocycled (6000 cycles, 5°C to 55°C). The fracture load values for final failure of intact and repaired crowns were measured with a universal testing machine, and failure types were recorded. Results: No significant differences ( p > 0.05) were found between the final failure values for the groups treated with 9.5% hydrofluoric acid (376 N) and airborne particle abrasion with either Al2O3 (432 N) or SiOx (582 N) followed by silanization, respectively. Significantly, higher ( p < 0.0001) final failure values (885 N) were obtained with the use of the FRC layer when compared with the other repaired groups. There was no significant difference ( p > 0.05) between the final fracture load of intact crowns (872 N) and those repaired with FRC (885 N) (One-way ANOVA with repeated measures, Bonferroni test). No significant difference in fracture loads was found between the 1st, 2nd, and 3rd repair cycles (558 N, 433 N, 485 N, respectively). Failure sites were predominantly at the alloy/veneering resin interface in Group 1; Groups 2 and 3 both showed more cohesive failures than Group 1. In the case of FRC, the failure pattern was exclusively cohesive between the two laminates of FRC layer. Conclusions: The conditioning methods (Groups 1 to 3) of the repair surfaces did not show differences between each other; each resulted in mean fracture loads at lower levels than that of the intact crowns. Addition of an FRC layer increased the fracture load to the level of intact crowns. This suggests that the use of FRC in repairs of metal-ceramic crowns might be a viable option. [source]

Apical surgery of a maxillary molar creating a maxillary sinus window using ultrasonics: a clinical case

INTERNATIONAL ENDODONTIC JOURNAL, Issue 11 2010
B. García
García B, Peñarrocha M, Peñarrocha MA, von Arx T. Apical surgery of a maxillary molar creating a maxillary sinus window using ultrasonics: a clinical case. International Endodontic Journal, 43, 1054,1061, 2010. Abstract Aim, To describe a method of carrying out apical surgery of a maxillary molar using ultrasonics to create a lateral sinus window into the maxillary sinus and an endoscope to enhance visibility during surgery. Summary, A 37-year-old female patient presented with tenderness to percussion of the maxillary second right molar. Root canal treatment had been undertaken, and the tooth restored with a metal-ceramic crown. Radiological examination revealed an apical radiolucency in close proximity to the maxillary sinus. Apical surgery of the molar was performed through the maxillary sinus, using ultrasonics for the osteotomy, creating a window in the lateral wall of the maxillary sinus. During surgery, the lining of the sinus was exposed and elevated without perforation. The root-end was resected using a round tungsten carbide drill, and the root-end cavity was prepared with ultrasonic retrotips. Root-end filling was accomplished with MTA®. An endoscope was used to examine the cut root face, the prepared cavity and the root-end filling. No intraoperative or postoperative complications were observed. At the 12-month follow-up, the tooth had no clinical signs or symptoms, and the radiograph demonstrated progressing resolution of the radiolucency. Key learning points ,,When conventional root canal retreatment cannot be performed or has failed, apical surgery may be considered, even in maxillary molars with roots in close proximity to the maxillary sinus. ,,Ultrasonic sinus window preparation allows more control and can minimize perforation of the sinus membrane when compared with conventional rotary drilling techniques. ,,The endoscope enhances visibility during endodontic surgery, thus improving the quality of the case. [source]

Metal-Ceramic Interface Evaluation of a Gold-Infiltrated Alloy

JOURNAL OF PROSTHODONTICS, Issue 7 2009
Rupal Vasani BDS
Abstract Purpose: The success of metal-ceramic systems partially depends on the formation of a stable bond between metal and porcelain. The purpose of this study was to investigate the porcelain/metal interface and the mechanism of interfacial bonding in a gold-infiltrated alloy (Captek). Materials and Methods: Captek specimens with feldspathic porcelain were evaluated by optical microscopy, scanning electron microscopy (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD), and the Schwickerath crack initiation test for metal-ceramic bond compatibility. Specimens were processed with or without Capbond, a bonding agent. A traditional metal-ceramic alloy was also analyzed with microscopy for comparative purposes. Results: Optical and scanning electron micrographs of Captek specimens processed with Capbond revealed close adaptation of porcelain to the surface of the metal with sporadic nodules extending from the Captek surface. In contrast, the specimens of Captek without Capbond showed a much flatter porcelain/metal interface. Comparatively, the porcelain/metal interface of the traditional metal-ceramic crown showed greater surface roughness than the Captek specimens. No metal oxides were observed at the porcelain/metal interface of the Captek specimens with XRD. During the Schwickerath test, the Captek specimens permanently deformed, not allowing for crack initiation at the porcelain/metal interface. Conclusions: Microscopy and XRD analysis showed that micromechanical interlocking is the primary mechanism of porcelain adherence to Captek metal. The use of Capbond prior to porcelain application to Captek results in gold nodules on the surface to aid retention. Existing metal-ceramic bond compatibility standardized tests are not sufficient for evaluating Captek, primarily due to the flexibility of the material. [source]

Effect of Aging on Coronal Microleakage in Access Cavities through Metal Ceramic Crowns Restored with Resin Composites

JOURNAL OF PROSTHODONTICS, Issue 5 2010
Ali Abdullah Alwan Al-Maqtari BDS
Abstract Purpose: The purpose of this in vitro study was to determine if packable resin composite with/without flowable resin composite has the ability to prevent coronal leakage in restored endodontic access openings following aging. Materials and Methods: Eighty simulated standardized access cavities of metal-ceramic crowns were fabricated and fixed on Vitrebond cavities filled with an epoxy resin. The specimens were randomly divided into two main groups: (1) Group A,Access cavities filled with only packable composite (Filtek P60); (2) Group B,Access cavities filled with Filtek P60 and a flowable composite (Filtek Z350) as liner. Each main group was further subdivided randomly into four subgroups according to water storage and thermocycling periods. All specimens were immersed in blue ink solution for 24 hours and then sectioned into quadrants. The extension of blue ink along the metal-ceramic crown/composite resin interface was measured linearly using image analyzer and then analyzed by three-way ANOVA and independent t -test with a Mann-Whitney test. The level of significance was set at p < 0.05. Results: All tested subgroups demonstrated different levels of microleakage. There was no significant difference related to restorative technique; however, there was a significant difference related to water storage and thermocycling. Conclusions: All tested techniques and materials in this study showed microleakage. Packable composite while a flowable liner showed a marginally better result than packable composite alone. Excessive thermocycling resulted in significant differences among the test groups. [source]