Crowns, Bridges and Dentures as well as Onlays are common treatments in restorative dentistry and are provided routinely at Priory Dental in Wells by all our dentists. Crowns are often used where teeth are already heavily restored with fillings or root canal fillings in order to improve the integrity of the final restoration and can be an aesthetic choice in certain circumstances. Bridges and Dentures are used to replace missing teeth with Bridges often replacing one or two teeth and Dentures replacing multiple missing teeth or all of the teeth (full dentures). In both cases dental implants can be an alternative and are being increasingly used instead of traditional bridges and dentures – for more information about implants see our dental implants page. Similarly, composite materials including composite veneers are used increasingly for aesthetic cases – see our smile makeovers page for more information on composite materials. Despite this, crowns bridges and dentures are still very common dental treatments in the many cases where other techniques are not suitable for any number of reasons. Your dentist will always help you select the most appropriate option for you.
Crowns are effectively a covering or ‘cap’ over what remains of a tooth following preparation to accept a crown. They are entirely bespoke for you being manufactured in a dental laboratory and then placed onto the remaining tooth by the dentist. This means that they usually require two appointments – one in order for the teeth to be prepared for the crown and a second for it to be inserted which is usually after a period of two weeks. In the interim we place a temporary crown where the real crown will go. The temporary crown is suitable for the short period while waiting for the final crown but is made of a softer material which is more difficult to clean and will wear rapidly. It is therefore not suitable for long-term use.
There are a number of different types of crown available which vary depending on the characteristics of the material they are made from – some are better for back teeth where function is more important and others better for front teeth where aesthetics are the primary concern. Some of the materials we use are described below.
Types of Dental Crown
Zirconia (Zirconium Oxide) is an exceptionally hard wearing ceramic material which can be used to provide white crowns at both the front and back of the mouth. It combines great strength with good aesthetics and is therefore one of the materials we use most often. It can however be less translucent than lithium disilicate materials which may be chosen over zirconia for front teeth if translucency is particularly important. Alternatively, new ‘high translucency’ zirconia materials are sometimes selected and in other cases we use what is called a ‘layered zirconia’ for front teeth and bridges which consists of a zirconia substructure with layered porcelain over the visible area of a front tooth which is prepared by hand by a dental technician to match adjacent teeth as closely as possible. These variants differ slightly in price depending on the work that has to go into producing them.
Lithium Disilicate (including IPS Emax and GC Lisi) is a glass-ceramic material which is particularly useful due to its higher translucency than Zirconia. It is particularly used for crowns and veneers on front teeth as well as some tooth-coloured onlays on back teeth. Like zirconia, it can also be layered with porcelain by hand in order to copy particular characteristics of adjacent teeth.
Gold is still used for producing some crowns although far less commonly than it was in the past. It is particularly useful for back teeth in patients who grind or clench their teeth. This is because it is an inherently softer material than some of the ceramics used and is therefore less likely to cause wear to the opposing teeth. Unfortunately however gold has become an expensive material to use due to worldwide gold prices and is disliked by some due to the appearance. Used appropriately on teeth which are less visible however, it can still be a very useful material.
Porcelain bonded crowns are far less commonly used today although was once the go-to white coloured crown especially within the NHS. They consist of a metal substructure faced in a porcelain to give it a white colouring. Despite the name this has no relation to the composite bonding you will find described on the smile makeovers page. Porcelain-bonded crowns and bridges can still be aesthetic but generally less so than zirconia and lithium disilicate materials due to a lack of translucency and therefore dullness to the appearance. Having two layers, one of which is metal, also means that they are often thicker and require the underlying tooth to be prepared further to account for this. We occasionally use them when the crown is to be mounted on a post as the post is already a metal and the greater preparation is irrelevant but even in these circumstances there is a tendency to use Zirconia as an alternative. We also still use this combination of materials for some bridges (see below).
Onlays are sometimes alternatives to crowns for back teeth and involve less preparation of the tooth. Usually only the top surface of the tooth is covered by the material produced in the laboratory which is commonly either Lithium Disilicate or very occasionally gold. You may also hear the term ‘Inlay’ but these were effectively a filling (usually gold) produced in a laboratory and stuck into a cavity. Due to the advances in filling materials such as composites which can be undertaken in a single visit by the dentist alone, inlays have largely become a thing of the past.
Bridges are designed to replace a missing tooth or ‘bridge the gap’. There are two types, a conventional bridge and a resin-retained bridge (also sometimes referred to as a ‘Maryland bridge’).
A conventional bridge usually consists of crowns on the adjacent teeth with a false tooth, known as a ‘pontic’, in the space. The three together are produced as a single unit in either Zirconia, layered zirconia or porcelain-bonded (to metal) – see information on these materials, although zirconia and layered zirconia is becoming increasingly common for us to use for this purpose. The appropriateness of a conventional bridge very much depends on the clinical situation and the status of the adjacent teeth on which your dentist will be able to advise.
A resin-retained bridge (or ‘Maryland’) is where the false tooth (or ‘pontic’) to fill the space is glued onto one of the adjacent teeth by means of a wing of metal that wraps around the inside of the supporting adjacent tooth. A resin based glue is used and hence the name resin-retained bridge. These are particularly useful for replacing single missing front teeth where the option of a dental implant is either inappropriate or has been decided against but have the disadvantage that they can de-bond (ie the glue can give way). For this reason they are rarely used on back teeth where the biting forces are higher.
Dentures are designed to usually replace multiple teeth with a single removable solution. They are generally cheaper than bridges and almost always cheaper than implant solutions but need to be removed at night and for cleaning.
There are two main types of denture and two materials. There is the partial denture which is used when some of the teeth in the upper or lower jaw need replacing and these can be made from either Acrylic or Cobalt-chromium (‘metal’). There is then the full denture which is used to replace all the teeth in the upper or lower jaw and is almost always made from Acrylic. Acrylic has the advantage of being cheaper but also more modifiable should further teeth be lost. Cobalt-Chromium is more expensive but can be clasped to the remaining teeth which can make it more stable and potentially less bulky and more comfortable. The choice isn’t often a simple as this however and your dentist will discuss with you what would be most appropriate and any other options you could consider, such as dental implants – for more information please see the dental implants page.