For individuals with damaged teeth, the issue extends beyond aesthetics to affect eating and chewing. Consequently, they often visit dental clinics for tooth restoration, with porcelain-fused-to-metal crowns being a common solution. So, what materials are used to construct these crowns?
Porcelain-fused-to-metal crowns are restorations designed to repair tooth damage while meeting functional and cosmetic requirements.Structurally, they consist of an inner crown and a porcelain veneer layer. By material, they are categorized into metal-based inner crowns and all-ceramic inner crowns. The specific materials for porcelain-fused-to-metal crowns are as follows:
1. Nickel-Chromium Alloy Crowns: Primarily composed of nickel and chromium.
2. Titanium alloy porcelain-fused-to-metal crowns: Considered a superior biocompatible material among standard metal-based crowns. Titanium content is only 4%–5%, with the remainder predominantly nickel-chromium, making them functionally similar to nickel-chromium alloy crowns.
3.Gold-plated porcelain-fused-to-metal crowns: Based on nickel-chromium porcelain, these feature gold plating at the tooth/gum contact points with an outer porcelain layer.
4. Cobalt-chromium porcelain-fused-to-metal crowns: Cobalt content does not exceed 30%, requiring nickel addition for malleability. Essentially a nickel-chromium alloy, it outperforms titanium alloy crowns.
5. Alloy porcelain-fused-to-metal crowns: Inner crowns containing over 50% silver, priced nearly equivalent to gold-based inner crowns.
6. Gold-alloy inner crown porcelain-fused-to-metal crowns:
5. Alloy Porcelain-Fused-to-Metal Crowns: Featuring inner crowns with over 50% silver content, these crowns approach the price point of gold-based inner crown porcelain-fused-to-metal crowns.
7. Gold-Deposited Porcelain Crowns: Utilizing deposition technology, these crowns eliminate one molding step, reducing fabrication errors. However, the low density of the gold paste increases the risk of porcelain chipping. 8. Platinum Porcelain Crowns: Featuring a platinum-based metal inner crown. Due to domestic dental platinum relying on German imports, which are now out of stock, these have virtually disappeared from clinical use.
8. Pure Titanium Porcelain-Fused-to-Metal Crowns: Titanium offers excellent biocompatibility, lightweight properties, chemical stability, and high mechanical strength, making it an ideal metal for dental restorations. However, its high melting point, susceptibility to oxidation, and significantly lower thermal expansion coefficient compared to porcelain (approximately 7 times lower than the ideal coefficient ratio) result in a higher risk of porcelain chipping than other porcelain-fused-to-metal types.
9. All-Ceramic Crowns: An inner crown is first fired using ceramic materials. Currently suitable only for anterior aesthetic restorations, not for replacing missing teeth.
12. Cast Ceramic Crowns: Divided into two generations. The first generation uses white garnet as the inner crown, also known as cast glass ceramics. The second generation uses lithium-based ceramics for the inner crown. Pricing is comparable to all-ceramic crowns.