Current ceramic materials with clinical application

 

Nowadays; all-ceramic prostheses are considered as the alternative materials compared with metal-ceramics. They offered increasingly great feel by emulating so normally the optical properties of teeth. Another later factor influencing the choice of dental ceramic materials is the high cost of precious metals such as gold. The common disadvantage of the first introduced ceramics production as feldspathic ones were the mechanical stability that limited the indication for all dental ceramic materials to anterior regions and to single units fixed prostheses for their higher esthetic properties.

 In the last years, numerous new dental ceramic materials were developed to increase the mechanical stability and also keeping their esthetic properties. Among those materials: leucite/ lithium-disilicate, glass ceramics, and oxide ceramic, for example, alumina and zirconia that gave off an impression of being promising for different indications (1,2). The first method of manufacturing the ordinary crown is lost wax-technique which is considered a technique sensitive as it requires several steps. In addition, it requires the therapeutic procedure to happen in numerous visits, expanding treatment time and potential complications .

However, using computer-aided design /computer-aided manufacturing which is a recent technique helped to produce (CAD/CAM) frameworks which allowed the dental professional to easily make ceramic crowns in one visit, without the necessity of forming temporary crowns that may lead to decrease postoperative complications and reduce treatment time

Organization Grouping and Clinical Application

Esthetic materials are shaped through at least two particular stages on a glass framework and crystalline filler particles (5). The improvement of higher properties of ceramics is result of the in wrinkled utilization of crystalline material and filler particles that are included in the glass lattice planned for improving the ceramic’s mechanical properties by decreasing less glass stage and, at long last, no glass content. Based on the micro-structural level, dental ceramic can be characterized by their organization of glass-to-crystalline proportion in three fundamental classes: 

• Prevalent smooth materials with high glass content. • Molecule filled glasses with variable measures of glass content. • Poly crystalline ceramic production without glass content. The glass-based structures used in dental ceramic start from feldspar minerals that contain transcendently silicon dioxide (silica or quartz), which have various proportions of alumina (aluminum oxide); they are in like manner called aluminosilicate glasses. Feldspathic glasses contain sodium and potassium, which can alter critical properties of the glass, for instance, decreasing ending temperatures or growing warm turn of events and withdrawal lead

Lithium-disilicate glass esthetic 

 

Glass ceramic production improved with lithium-disilicate precious metals (SiO2- Li2O) were created by Ivoclar Vivadent to be utilized with the lost wax heat pressed technique (IPS Empress® 2 and IPS e.max® Press) and later on with the Computer Aided Design/CAM innovation (IPS e.max® Computer aided design). The esthetic microstructure comprises of exceptionally interlocked lithium-disilicate precious stones, 0.6 mm long and 0.8 mm in distance across (7). Because of the moderately low refractive record of the lithium-disilicate gems, this material has high translucency shows disdain toward its high crystalline substance.

The IPS e.max lithium-disilicate ceramic can be utilized in solid application for esthetics, onlays, and posterior crowns or as a center material for crowns and three-unit FDPs in the anterior area. Machinable lithium-disilicate squares (IPS e.max computer aided design) were recently developed to be utilized with computer- aided design CAD/CAM handling innovation. These squares are exposed to a two-phase crystallization process. During the last crystallization process, 70% of precious stone volume is incorporate-evaluated in a glass framework, expanding its last opposition. Furthermore, in this stage the blue shade of the recrystallized square is changed to the chosen tooth  conceal. The last restoration has a flexural quality of 360 MPa; these are demonstrated for foremost or back crowns, embed crowns, trims, onlays, and facade.

ompletely Polycrystalline or Polycrystalline ceramic production/No Glass Content 

 

The advancement of high-quality polycrystalline ceramic production resulted from the expanded utilization of crystalline material with ensuing diminished measures of the glass stage, until no glass was present in the material microstructure (8). These ceramic productions are framed by legitimately sintering gems together, bringing about a thick, glass-free polycrystalline structure.

• Composed of: - Alumina; Nobel BioCare grasped the idea of computer aided design/CAM innovation to manufacture every single ceramic crown made out of a thickly sintered, high-virtue aluminumoxide coping joined with a low-melding all-ceramic veneering porcelain. Copings contain 99.5% to 99.9% high-immaculateness aluminum oxide. - Zirconia; is a polymorphic material that happens in three crystalline structures that are temperature-subordinate: monoclinic, tetragonal, and cubic. The zirconia ceramic production is described as a thick, monocrystalline homogeneity, and have low warm conductivity, low erosion potential, great radiopacity, high biocompatibility, low bacterial surface grip, and positive optical properties. Contrasted and high-quality alumina ceramics, zirconia has twice the flexural quality.

 

Classification according to techniques:

Fabricating All- Ceramic Crown Restoration Currently, special structures are utilized to fabricate metal-free prosthesis: powder condensation, pressing, slip casting, and CAD/CAM milling of ceramics (12).
Powder Condensation Powder condensation is considered to be the gold popular approach of fabricating allceramic crowns (13). Moist porcelain powder is utilized to construct up the crown and then extra  humidity is eradicated to condense the powder particles. Then the porcelain is fired below a vacuum however, a massive quantity of residual porosity is found. Although all-ceramic crowns fabricated through this method have low strength, they are extra esthetic than crowns which have been made by the way of the other methods due to their higher translucency .

Heat Press Technique The misplaced wax approach is used to produce all-ceramic crowns by means of the heat press technique. It consists of heating pressable ceramics ingots to an excessive temperature, at which they flip out to be extraordinarily viscous liquid and then are pressed progressively into the shaped misplaced wax mold. All-ceramic crowns fabricated by this method have decreased porosity and top accuracy of fit (1 3). All pressable ceramic substances are supplied in the structure of ingots. The first generation of the heat-pressed ceramics used to be composed of 35-45% leucite by the way of volume as crystalline segment whilst the 2d technology comprised approximately 65% lithium disilicate by the way of extent as the major crystalline phase (1 4).

Slip Cast Technique A slurry of ceramic powder particles suspended in fluid is referred to as a slip. Forming a bad reproduction and then introducing the slip into the reproduction accomplishes this technique, which produces ceramic that is porous and weak (1 3,1 4). The use of this approach is confined due to the fact that it requires difficult steps to accomplish unique adaption and may stop up with inner flaws that deteriorate the material

References

(1)- Pjetursson BE, Sailer I, Zwahlen M, Hämmerle CH. A systematic review of the survival and complication rates of all‐ceramic and metal–ceramic reconstructions after an observation period of at least 3 years. Part I: single crowns. Clinical oral implants research. 2007 Jun; 18:73 -85. 

(2)- Sailer I, Pjetursson BE, Zwahlen M, Hämmerle CH. A systematic review of the survival and complication rates of all‐ceramic and metal–ceramic reconstructions after an observation period of at least 3 years. Part II: fixed dental prostheses. Clinical oral implants research. 2007 Jun; 18:86- 96. 

(3)- Ghazy M, El‐Mowafy O, Roperto R. Microleakage of Porcelain and Composite Machined Crowns Cemented with Self‐Adhesive or Conventional Resin Cement. Journal of Prosthodontics: Implant, Esthetic and Reconstructive Dentistry. 2010 Oct;19(7):523-30. 

(4)- Fasbinder DJ. Clinical performance of chairside CAD/CAM restorations. The Journal of the American Dental Association. 2006 Sep 1; 137:22S-31S. 

(5)- Kelly JR, Benetti P. Ceramic materials in dentistry: historical evolution and current practice. Australian dental journal. 2011 Jun; 56:84-96. 

(6)- Giordano R, McLaren EA. Ceramics overview: classification by microstructure and processing methods. Compendium of continuing education in dentistry (Jamesburg, NJ: 1995). 2010;31(9):682-7. 

(7)- Guess PC, Schultheis S, Bonfante EA, Coelho PG, Ferencz JL, Silva NR. All-ceramic systems: laboratory and clinical performance. Dental clinics. 2011 Apr 1;55(2):333-52.
(8)- Özkurt Z, Kazazoğlu E. Clinical success of zirconia in dental applications. Journal of Prosthodontics: Implant, Esthetic and Reconstructive Dentistry. 2010 Jan;19(1):64-8. 

(9)- Santos MJ, Costa MD, Rubo JH, Pegoraro LF, Santos Jr GC. Current all-ceramic systems in dentistry: a review. Compend Contin Educ Dent. 2015 Jan;36(1):31 -7. 

(10)- Anusavice K, Shen C, Rawls R. Phillips’ Science of Dental Material.12th ed. St. Louis, MI: Saunders, Elsevier Inc; 2013:418–473. 

(11)- Giordano R, Sabrosa CE. Zirconia: material background and clinical application. Compendium of continuing education in dentistry (Jamesburg, NJ: 1995). 2010;31(9):710-5. 

(12)- Dundar M, Gungor MA, Cal E. Multidisciplinary approach to restoring anterior maxillary partial edentulous area using an IPS Empress 2 fixed partial denture: A clinical report. The Journal of prosthetic dentistry. 2003 Apr 1;89(4):327-30. 

(13)- Griggs JA. Recent advances in materials for all-ceramic restorations. Dental Clinics of North America. 2007 Jul 1;51(3):713-27. 

(14)- Mously HA, Finkelman M, Zandparsa R, Hirayama H. Marginal and internal adaptation of ceramic crown restorations fabricated with CAD/CAM technology and the heat-press technique. The Journal of prosthetic dentistry. 2014 Aug 1;112(2):249-56. 

(15)- Pallis K, Griggs JA, Woody RD, Guillen GE, Miller AW. Fracture resistance of three allceramic restorative systems for posterior applications. The Journal of prosthetic dentistry. 2004 Jun 1;91(6):561 -9.