Dentures, Crown and Bridges
What is a Dental Crown?
Crowns are used as a fixed covering over a decayed or damaged tooth which needs restoration. They are cemented to a tooth and unlike dentures cannot be removed by patients. They strengthen a damaged tooth and can also be used to improve appearances, functionality and aesthetics. Besides these, they are placed at the top of an implant to replace a missing tooth.
When is a crown recommended?
When a large tooth structure has been lost due to decay
To replace a missing tooth with implants
Protect the root canal treated tooth from fracture
To improve aesthetics of a discoloured tooth
What are the types of crowns available?
Metal Crowns: They are made up of different dental alloys like gold, cobalt chromium etc. They are recommended in posterior teeth where aesthetics is not of concern, less space is available for building a PFM crown or the patient is on a tight budget.
Porcelain Fused Metal Crowns: PFM crowns are artificial teeth with a metal base fused to porcelain coping which resembles natural tooth colour. They are aesthetically pleasing and can be used in anterior regions as well.
Zirconia, E-Max or Metal Free Crowns: Metal-free crowns are usually made up of zirconium or lithium-disilicate (e-max by Ivoclar Vivadent) ceramic. These materials are similar to glass but are strong enough like a natural tooth. Zirconium crowns are very popular these days. They are cad-cam manufactured thus ensuring proper fit and accuracy. It’s a white material and was initially used in space technology. Zirconium crowns have extraordinary aesthetic and mechanical properties. Long span Metal-free bridges can be made out of it. Though this turned out to be a ground-breaking material in crown production technology, aesthetic properties of lithium-disilicate ceramic are still unsurpassed.
A bridge is used to replace one or more missing teeth from the dental arch. They take support from the adjacent natural teeth or implants as pillars (called abutments) and replace the gap by artificial teeth (pontics). The pontics are attached to the crowns covering the abutments and replace the missing teeth permanently. Unlike dentures, they are fixed and cannot be removed by patients, but only at a dental clinic.
Complete dentures are made in completely edentulous patients or patients who don’t have any tooth left in oral cavity. They can be placed in the mouth about 8-12 weeks after removal of teeth and healing of extraction sockets. They are advised for geriatric patients and are conveniently removed and cleaned by them.
Overdentures or Implant Supported Dentures
They are similar to complete dentures but they are supported over implants or natural tooth for retention. Their baseplate doesn’t sit directly to the arch but on the implant tops. This helps in preservation of the underlying ridge bones and prevents further resorption. They can be removed and cleaned by the patients and have good aesthetics.
Removable Partial Dentures
A removable partial denture consists of artificial teeth attached to a pink or gum-coloured denture base placed in the mouth. They take support from adjacent teeth in the mouth. They are very natural looking and not only replace the missing teeth but also help in keeping the remaining teeth in position.
They are just like regular dentures but with increased flexibility
and comfort. They are less brittle and do not break and shatter
when dropped. They don’t require denture adhesive and cling to
gums naturally. They are thin and clear and shows natural
contour and colour of gums.
Demerits of Removable Dentures
While complete and partial removable dentures restore functionality and aesthetics and help a patient chew and speak, they do not help in cessation of bone loss with time in absence of natural teeth. This leads to gradual bone loss beneath the denture base plate and which ultimately results in ill-fitting of the existing denture over time. They need to be replaced in a few years as they become unfit for proper retention and usage.
Hammer Test for Zirconia Crown