Prosthodontics

Dentures

Dentures, also known as false teeth, are prosthetic devices constructed to replace missing teeth, and which are supported by surrounding soft and hard tissues of the oral cavity. Conventional dentures are removable, however there are many different denture designs, some which rely on bonding or clasping onto teeth or dental implants. There are two main categories of dentures, depending on whether they are used to replace missing teeth on the mandibular arch or the maxillary arch.

Types :–

Removable partial dentures

Removable partial dentures are for patients who are missing some of their teeth on a particular arch. Fixed partial dentures, also known as “crown and bridge”, are made from crowns that are fitted on the remaining teeth to act as abutments and pontics made from materials to resemble the missing teeth. Fixed bridges are more expensive than removable appliances but are more stable .

Complete dentures

Conversely, complete dentures or full dentures are worn by patients who are missing all of the teeth in a single arch (i.e. the maxillary (upper) or mandibular (lower) arch).

CROWNS AND BRIDGES

When teeth are heavily decayed they may be too weak to survive with just a filling. By placing a crown, a tooth may be given a new lease of life. Even when a single tooth is lost a denture may not be required as a bridge can be made which spans the gap with a tooth attached to those next to the space.

When a tooth is heavily decayed it is more likely to fracture and lose considerable tooth substance. The greater risk is that a fracture line may go below the margin of the gum which makes restoration more difficult or near impossible.

Crowns may be made from several different materials porcelain being the most common types Porcelain is usually always used for the front teeth but may be used for the back teeth. This material can be made to appear very natural though several factors affect this Some porcelain crowns have metal inside which gives strength and support to the porcelain. This acts as a barrier for light and gives the crown a dull colour. On posterior teeth this won’t be noticed but in the front of the mouth it can occasionally be a problem as the tooth looks duller than the natural teeth.

Bridges

A bridge allows the dentist to replace lost teeth without the use of a denture or dental implant. Basically a false tooth is held in place by being attached to a tooth next door. The disadvantage is that the teeth next to the space have to be prepared in a similiar way to a crown in order to accept the bridge. If these teeth already have crowns or big restorations then this is not a problem, the major concern however is when these teeth have small or no restorations (fillings). One compromise is the ‘acid etched bridge’, with this type a fine ledge is placed on the back of the adjacent teeth.

One disadvantage of a bridge is that the patient should wait three months before placement as the ‘gum’ shrinks’ after a tooth is extracted. If the bridge was fitted early a gap would appear underneath the pontic (the false tooth). At the back of the mouth this may not be a problem, at the front of the mouth however this may appear as a black line along the gum.

Post and Core

When the top of a tooth is lost due to decay there may be very little for the crown to actually hold onto. To gain ‘retention’ as dentists call it, a post is placed inside the tooth which forms a peg on top of the tooth and acts as a seat for the crown. Post crowns have a shorter lifespan than normal crowns as the roots may be brittle and weaker. Usually a post crown is a better option than having the tooth extracted with a subsequent denture or bridge.