Pilot study of the relationship between the hardness and abrasion resistance of two base metal alloys used for metal-ceramic restorations

2001 ◽  
Vol 85 (2) ◽  
pp. 190-194
Author(s):  
Osvaldo L. Bezzon ◽  
Celso de Barros ◽  
João M.D. de Almeid ◽  
Pedro L. Di Lorenzo
2009 ◽  
Vol 1 (2) ◽  
pp. 25-29
Author(s):  
Andre Rayne Le Roux

Reduction in base metal alloy thickness will permit additional porcelain depth and improved aesthetics but unfortunately little information exists regarding the thickness to which base metal alloys may be reduced in comparison to noble metal alloys for metal ceramic restorations. Even with comparison of noble metal alloys the aesthetic benefits are restricted to improving aesthetics in base metal restoration further, since noble metal alloys are generally regarded as providing superior aesthetics to base metal restorative alloys. Purpose: The objective of this study was to determine whether a significant reduction in thickness could be achieved using a base metal alloy as compared to a noble metal alloy and the thickness to which base metal alloy substructures could safely be reduced while still providing the same resistance to fracture of the porcelain. Material and methods: Tensile strength tests (N) of the modulus of rupture of the porcelain were performed on 40 base metal alloy (Wiron 99, Bego, Germany) and 12 noble metal alloy rectangular specimens (5.8 mm wide and 15.0 mm long) bonded to a standardized 1.0 mm thickness of dentine Creation porcelain. The base metal alloy thickness varied in 0.1mm increments from 0.1 to 0.4 mm. The results were compared to 12 noble metal alloy (Bio Y 81, Argen, South Africa) specimens of recommended minimum thickness (0.3 mm). Data for the results was obtained using a universal tensile testing instrument, which was set to operate at a cross head speed of 0.5mm (Instron Mini 44, Instron corporation U.S.A). The applied force (N) that measured the modulus of rupture of each specimen was printed from a computer connected to the Instron Mini 44 that operated on a 95% level of confidence. Instron Agents (Durban, South Africa) performed the calibration and setting up of the machine prior to testing the specimens. Results: The results indicated a permissible 33.33% reduction in the base metal alloy specimens as compared to the noble metal alloy control specimens. This was deduced from the reduction in alloy thickness of up to 0.2 mm for base metal alloy specimens as compared to the 0.3 mm noble metal alloy specimens. The recommended thickness to which the base metal alloys could be reduced without distortion of the alloy was also 0.2 mm. The one-way ANOVA showed a level of significance of (α=05).


2013 ◽  
Vol 07 (03) ◽  
pp. 373-376
Author(s):  
Tuncer Burak Ozcelik ◽  
Burak Yilmaz

ABSTRACTMetal ceramic partial fixed dental prostheses have been commonly used for the replacement of missing teeth for many years. Because of an increase in the price of gold, base metal alloys have been the choice of alloy for the fabrication of metal ceramic restorations in many dental clinics. Some major disadvantages of base metals are their corrosion and the dark coloration they may cause at the crown margins. This article describes a galvanic gold-plating technique, which is used to minimize corrosion and improve the esthetics of metal ceramic restorations fabricated with Cr-Co base metal alloys. This technique involves the deposition of a 6 μm to 8 μm 24 K gold layer directly onto the Cr-Co cast prosthesis framework. The technique improves metal surface properties, making them more biocompatible and usable, however, requires additional equipment and experienced laboratory technicians. Clinical studies should be performed to corroborate the long term success of this technique.


2015 ◽  
Vol 1 (2-4) ◽  
pp. 70-75 ◽  
Author(s):  
Charlotta Holm ◽  
Else Morisbak ◽  
Torill Kalfoss ◽  
Jon E. Dahl

2017 ◽  
Vol 18 (2) ◽  
pp. 112-116 ◽  
Author(s):  
Khurshid A Mattoo ◽  
Faisal M Alkhayrat ◽  
Hussam A Madkhali ◽  
Ibrahim H Geathy ◽  
Mohammed AW Qahhar ◽  
...  

ABSTRACT Introduction Esthetic perceptions could differ between the dentist and his patients among various regions and cultures. Aim The aims of this study were to evaluate the subjective differences between the dentist and the patient in terms of esthetics of metal-ceramic crowns (MCcs). The study also aims to compare the mesiodistal (MD) and buccolingual (BL) dimensions of the cemented crown with its respective natural antimeric tooth. Materials and methods A total of 85 patients seeking treatment for a single crown (MC) were treated by the undergraduate students under supervision of respective academic staff. After cementation of the crowns, a 9-point questionnaire was given to patient and different dentists. A treatment cast for every single crown was poured. Then, the MD and BL dimensions of the crowns were compared against their respective antimeric tooth. Results The dentists and the patients agreed in the range of 50.5 to 90.5%. Least subjective differences were found for the length and width of the cemented crowns. The highest differences were noted for symmetry between the cemented crown and its antimeric natural tooth. A total of 31 to 38% of the patients differed from the dentist's evaluation for shade of the crown, color of the crown at the margin, contour of the crown, and the relationship of the crowns with the surrounding gingiva. The highest MD and BL dimensions were in the cemented crown of canines, while the lowest MD and BL diameters were for the cemented crowns of the lateral incisor crowns. Conclusion Dentist and patient mostly agreed in terms of length (90%), width (81%) and relation of crown with free gingiva (74%). However, they differed mostly on the symmetry of the cemented crowns. The highest MD dimensions and BL diameter were in the cemented MCcs of canine, while the lowest were with lateral incisors. Clinical significance While fabricating a dental prosthesis, the dentist must know about patients’ perception of esthetics; otherwise both clinical and laboratory efforts would not be enough to satisfy the esthetic needs of the patient even if the restoration is technically correct. Perceptions related to symmetry differ mostly between dentist and patient. How to cite the article Al Moaleem MM, Alkhayrat FM, Madkhali HA, Geathy IH, Qahhar MAW, Yaqoub A, Mattoo KA. Subjective Differences between Dentists and Patients about Relative Quality of Metal Ceramic Restorations placed in the Esthetic Zone. J Contemp Dent Pract 2017;18(2):112-116.


Sign in / Sign up

Export Citation Format

Share Document